Sample records for accelerated hyperfractionated imrt

  1. Fast online Monte Carlo-based IMRT planning for the MRI linear accelerator

    NASA Astrophysics Data System (ADS)

    Bol, G. H.; Hissoiny, S.; Lagendijk, J. J. W.; Raaymakers, B. W.

    2012-03-01

    The MRI accelerator, a combination of a 6 MV linear accelerator with a 1.5 T MRI, facilitates continuous patient anatomy updates regarding translations, rotations and deformations of targets and organs at risk. Accounting for these demands high speed, online intensity-modulated radiotherapy (IMRT) re-optimization. In this paper, a fast IMRT optimization system is described which combines a GPU-based Monte Carlo dose calculation engine for online beamlet generation and a fast inverse dose optimization algorithm. Tightly conformal IMRT plans are generated for four phantom cases and two clinical cases (cervix and kidney) in the presence of the magnetic fields of 0 and 1.5 T. We show that for the presented cases the beamlet generation and optimization routines are fast enough for online IMRT planning. Furthermore, there is no influence of the magnetic field on plan quality and complexity, and equal optimization constraints at 0 and 1.5 T lead to almost identical dose distributions.

  2. Shielding evaluation for IMRT implementation in an existing accelerator vault

    PubMed Central

    Price, R. A.; Chibani, O.; Ma, C.‐M.

    2003-01-01

    A formalism is developed for evaluating the shielding in an existing vault to be used for IMRT. Existing exposure rate measurements are utilized as well as a newly developed effective modulation scaling factor. Examples are given for vaults housing 6, 10 and 18 MV linear accelerators. The use of an 18 MV Siemens linear accelerator is evaluated for IMRT delivery with respect to neutron production and the effects on individual patients. A modified modulation scaling factor is developed and the risk of the incurrence of fatal secondary malignancies is estimated. The difference in neutron production between 18 MV Varian and Siemens accelerators is estimated using Monte Carlo results. The neutron production from the Siemens accelerator is found to be approximately 4 times less than that of the Varian accelerator resulting in a risk of fatal secondary malignancy occurrence of approximately 1.6% when using the SMLC delivery technique and our measured modulation scaling factors. This compares with a previously published value of 1.6% for routine 3D CRT delivery on the Varian accelerator. PACS number(s): 87.52.Ga, 87.52.Px, 87.53.Qc, 87.53.Wz PMID:12841794

  3. Accelerated hyperfractionated radiotherapy for cervical cancer: multi-institutional prospective study of forum for nuclear cooperation in Asia among eight Asian countries.

    PubMed

    Ohno, Tatsuya; Nakano, Takashi; Kato, Shingo; Koo, Cho Chul; Chansilpa, Yaowalak; Pattaranutaporn, Pittayapoom; Calaguas, Miriam Joy C; de Los Reyes, Rey H; Zhou, Beibei; Zhou, Juying; Susworo, Raden; Supriana, Nana; Dung, To Anh; Ismail, Fuad; Sato, Sinichiro; Suto, Hisao; Kutsutani-Nakamura, Yuzuru; Tsujii, Hirohiko

    2008-04-01

    To evaluate the toxicity and efficacy of accelerated hyperfractionated radiotherapy (RT) for locally advanced cervical cancer. A multi-institutional prospective single-arm study was conducted among eight Asian countries. Between 1999 and 2002, 120 patients (64 with Stage IIB and 56 with Stage IIIB) with squamous cell carcinoma of the cervix were treated with accelerated hyperfractionated RT. External beam RT consisted of 30 Gy to the whole pelvis, 1.5 Gy/fraction twice daily, followed by 20 Gy of pelvic RT with central shielding at a dose of 2-Gy fractions daily. A small bowel displacement device was used with the patient in the prone position. In addition to central shielding RT, intracavitary brachytherapy was started. Acute and late morbidities were graded according to the Radiation Therapy Oncology Group and Radiation Therapy Oncology Group/European Organization for Research and Treatment of Cancer criteria. The median overall treatment time was 35 days. The median follow-up time for surviving patients was 4.7 years. The 5-year pelvic control and overall survival rate for all patients was 84% and 70%, respectively. The 5-year pelvic control and overall survival rate was 78% and 69% for tumors > or = 6 cm in diameter, respectively. No treatment-related death occurred. Grade 3-4 late toxicities of the small intestine, large intestine, and bladder were observed in 1, 1, and 2 patients, respectively. The 5-year actuarial rate of Grade 3-4 late toxicity at any site was 5%. The results of our study have shown that accelerated hyperfractionated RT achieved sufficient pelvic control and survival without increasing severe toxicity. This treatment could be feasible in those Asian countries where chemoradiotherapy is not available.

  4. Accelerated Hyperfractionated Radiotherapy for Cervical Cancer: Multi-Institutional Prospective Study of Forum for Nuclear Cooperation in Asia Among Eight Asian Countries

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ohno, Tatsuya; Nakano, Takashi; Kato, Shingo

    2008-04-01

    Purpose: To evaluate the toxicity and efficacy of accelerated hyperfractionated radiotherapy (RT) for locally advanced cervical cancer. Methods and Materials: A multi-institutional prospective single-arm study was conducted among eight Asian countries. Between 1999 and 2002, 120 patients (64 with Stage IIB and 56 with Stage IIIB) with squamous cell carcinoma of the cervix were treated with accelerated hyperfractionated RT. External beam RT consisted of 30 Gy to the whole pelvis, 1.5 Gy/fraction twice daily, followed by 20 Gy of pelvic RT with central shielding at a dose of 2-Gy fractions daily. A small bowel displacement device was used with themore » patient in the prone position. In addition to central shielding RT, intracavitary brachytherapy was started. Acute and late morbidities were graded according to the Radiation Therapy Oncology Group and Radiation Therapy Oncology Group/European Organization for Research and Treatment of Cancer criteria. Results: The median overall treatment time was 35 days. The median follow-up time for surviving patients was 4.7 years. The 5-year pelvic control and overall survival rate for all patients was 84% and 70%, respectively. The 5-year pelvic control and overall survival rate was 78% and 69% for tumors {>=}6 cm in diameter, respectively. No treatment-related death occurred. Grade 3-4 late toxicities of the small intestine, large intestine, and bladder were observed in 1, 1, and 2 patients, respectively. The 5-year actuarial rate of Grade 3-4 late toxicity at any site was 5%. Conclusion: The results of our study have shown that accelerated hyperfractionated RT achieved sufficient pelvic control and survival without increasing severe toxicity. This treatment could be feasible in those Asian countries where chemoradiotherapy is not available.« less

  5. Dosimetric advantages of IMPT over IMRT for laser-accelerated proton beams

    NASA Astrophysics Data System (ADS)

    Luo, W.; Li, J.; Fourkal, E.; Fan, J.; Xu, X.; Chen, Z.; Jin, L.; Price, R.; Ma, C.-M.

    2008-12-01

    As a clinical application of an exciting scientific breakthrough, a compact and cost-efficient proton therapy unit using high-power laser acceleration is being developed at Fox Chase Cancer Center. The significance of this application depends on whether or not it can yield dosimetric superiority over intensity-modulated radiation therapy (IMRT). The goal of this study is to show how laser-accelerated proton beams with broad energy spreads can be optimally used for proton therapy including intensity-modulated proton therapy (IMPT) and achieve dosimetric superiority over IMRT for prostate cancer. Desired energies and spreads with a varying δE/E were selected with the particle selection device and used to generate spread-out Bragg peaks (SOBPs). Proton plans were generated on an in-house Monte Carlo-based inverse-planning system. Fifteen prostate IMRT plans previously used for patient treatment have been included for comparison. Identical dose prescriptions, beam arrangement and consistent dose constrains were used for IMRT and IMPT plans to show the dosimetric differences that were caused only by the different physical characteristics of proton and photon beams. Different optimization constrains and beam arrangements were also used to find optimal IMPT. The results show that conventional proton therapy (CPT) plans without intensity modulation were not superior to IMRT, but IMPT can generate better proton plans if appropriate beam setup and optimization are used. Compared to IMRT, IMPT can reduce the target dose heterogeneity ((D5-D95)/D95) by up to 56%. The volume receiving 65 Gy and higher (V65) for the bladder and the rectum can be reduced by up to 45% and 88%, respectively, while the volume receiving 40 Gy and higher (V40) for the bladder and the rectum can be reduced by up to 49% and 68%, respectively. IMPT can also reduce the whole body non-target tissue dose by up to 61% or a factor 2.5. This study has shown that the laser accelerator under development has a

  6. Protocol for the isotoxic intensity modulated radiotherapy (IMRT) in stage III non-small cell lung cancer (NSCLC): a feasibility study.

    PubMed

    Haslett, Kate; Franks, Kevin; Hanna, Gerard G; Harden, Susan; Hatton, Matthew; Harrow, Stephen; McDonald, Fiona; Ashcroft, Linda; Falk, Sally; Groom, Nicki; Harris, Catherine; McCloskey, Paula; Whitehurst, Philip; Bayman, Neil; Faivre-Finn, Corinne

    2016-04-15

    The majority of stage III patients with non-small cell lung cancer (NSCLC) are unsuitable for concurrent chemoradiotherapy, the non-surgical gold standard of care. As the alternative treatment options of sequential chemoradiotherapy and radiotherapy alone are associated with high local failure rates, various intensification strategies have been employed. There is evidence to suggest that altered fractionation using hyperfractionation, acceleration, dose escalation, and individualisation may be of benefit. The MAASTRO group have pioneered the concept of 'isotoxic' radiotherapy allowing for individualised dose escalation using hyperfractionated accelerated radiotherapy based on predefined normal tissue constraints. This study aims to evaluate whether delivering isotoxic radiotherapy using intensity modulated radiotherapy (IMRT) is achievable. Isotoxic IMRT is a multicentre feasibility study. From June 2014, a total of 35 patients from 7 UK centres, with a proven histological or cytological diagnosis of inoperable NSCLC, unsuitable for concurrent chemoradiotherapy will be recruited. A minimum of 2 cycles of induction chemotherapy is mandated before starting isotoxic radiotherapy. The dose of radiation will be increased until one or more of the organs at risk tolerance or the maximum dose of 79.2 Gy is reached. The primary end point is feasibility, with accrual rates, local control and overall survival our secondary end points. Patients will be followed up for 5 years. The study has received ethical approval (REC reference: 13/NW/0480) from the National Research Ethics Service (NRES) Committee North West-Greater Manchester South. The trial is conducted in accordance with the Declaration of Helsinki and Good Clinical Practice (GCP). The trial results will be published in a peer-reviewed journal and presented internationally. NCT01836692; Pre-results. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence

  7. Supratentorial primitive neuroectodermal tumors (S-PNET) in children: A prospective experience with adjuvant intensive chemotherapy and hyperfractionated accelerated radiotherapy

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Massimino, Maura; Gandola, Lorenza; Spreafico, Filippo

    Purpose: Supratentorial primitive neuroectodermal tumors (S-PNET) are rare and have a grim prognosis, frequently taking an aggressive course with local relapse and metastatic spread. We report the results of a mono-institutional therapeutic trial. Methods and Materials: We enrolled 15 consecutive patients to preradiation chemotherapy (CT) consisting of high-dose methotrexate, high-dose etoposide, high-dose cyclophosphamide, and high-dose carboplatin, craniospinal irradiation (CSI) with hyperfractionated accelerated radiotherapy (HART) plus focal boost, maintenance with vincristine/lomustine or consolidation with high-dose thiotepa followed by autologous stem-cell rescue. Results: Median age was 9 years; 7 were male, 8 female. Site of disease was pineal in 3, elsewhere inmore » 12. Six patients were had no evidence of disease after surgery (NED). Of those with evidence of disease after surgery (ED), 2 had central nervous system spread. Of the 9 ED patients, 2 had complete response (CR) and 2 partial response (PR) after CT, 4 stable disease, and 1 progressive disease. Of the 7 ED patients before radiotherapy, 1 had CR, 4 PR, and 2 minor response, thus obtaining a 44% CR + PR after CT and 71% after HART. Because of rapid progression in 2 of the first 5 patients, high-dose thiotepa was systematically adopted after HART in the subsequent 10 patients. Six of 15 patients relapsed (4 locally, 1 locally with dissemination, 1 with dissemination) a mean of 6 months after starting CT, 2 developed second tumors; 5 of 6 relapsers died at a median of 13 months. Three-year progression-free survival, event-free survival, and overall survival were 54%, 34%, and 61%, respectively. Conclusion: Hyperfractionated accelerated RT was the main tool in obtaining responses in S-PNET; introducing the myeloablative phase improved the prognosis (3/10 vs. 3/5 relapses), though the outcome remained unsatisfactory despite the adoption of this intensive treatment.« less

  8. Accelerating IMRT optimization by voxel sampling

    NASA Astrophysics Data System (ADS)

    Martin, Benjamin C.; Bortfeld, Thomas R.; Castañon, David A.

    2007-12-01

    This paper presents a new method for accelerating intensity-modulated radiation therapy (IMRT) optimization using voxel sampling. Rather than calculating the dose to the entire patient at each step in the optimization, the dose is only calculated for some randomly selected voxels. Those voxels are then used to calculate estimates of the objective and gradient which are used in a randomized version of a steepest descent algorithm. By selecting different voxels on each step, we are able to find an optimal solution to the full problem. We also present an algorithm to automatically choose the best sampling rate for each structure within the patient during the optimization. Seeking further improvements, we experimented with several other gradient-based optimization algorithms and found that the delta-bar-delta algorithm performs well despite the randomness. Overall, we were able to achieve approximately an order of magnitude speedup on our test case as compared to steepest descent.

  9. Accelerated hyperfractionated intensity-modulated radiotherapy for recurrent/unresectable rectal cancer in patients with previous pelvic irradiation: results of a phase II study.

    PubMed

    Cai, Gang; Zhu, Ji; Hu, Weigang; Zhang, Zhen

    2014-12-11

    This study was conducted to investigate the local effects and toxicity of accelerated hyperfractionated intensity-modulated radiotherapy for recurrent/unresectable rectal cancer in patients with previous pelvic irradiation. Twenty-two patients with recurrent/unresectable rectal cancer who previously received pelvic irradiation were enrolled in our single-center trial between January 2007 and August 2012. Reirradiation was scheduled for up to 39 Gy in 30 fractions using intensity-modulated radiotherapy plans. The dose was delivered via a hyperfractionation schedule of 1.3 Gy twice daily. Patient follow-up was performed by clinical examination, CT/MRI, or PET/CT every 3 months for the first 2 years and every 6 months thereafter. Tumor response was evaluated 1 month after reirradiation by CT/MRI based on the RECIST criteria. Adverse events were assessed using the National Cancer Institute (NCI) common toxicity criteria (version 3.0). The median time from the end of the initial radiation therapy to reirradiation was 30 months (range, 18-93 months). Overall local responses were observed in 9 patients (40.9%). None of the patients achieved a complete response (CR), and 9 patients (40.9%) had a partial response (PR). Thirteen patients failed to achieve a clinical response: 12 (54.5%) presented with stable disease (SD) and 1 (4.5%) with progressive disease (PD). Among all the patients who underwent reirradiation, partial or complete symptomatic relief was achieved in 6 patients (27.3%) and 13 patients (59.1%), respectively. Grade 4 acute toxicity and treatment-related deaths were not observed. The following grade 3 acute toxicities were observed: diarrhea (2 patients, 9.1%), cystitis (1 patient, 4.5%), dermatitis (1 patient, 4.5%), and intestinal obstruction (1 patient, 4.5%). Late toxicity was infrequent. Chronic severe diarrhea, small bowel obstruction, and dysuria were observed in 2 (9.1%), 1 (4.5%) and 2 (9.1%) of the patients, respectively. This study showed that

  10. Analysis of peripheral doses for base of tongue treatment by linear accelerator and helical TomoTherapy IMRT

    PubMed Central

    Lamba, Michael A. S.; Elson, Howard R.

    2010-01-01

    The purpose of this study was to compare the peripheral doses to various organs from a typical head and neck intensity‐modulated radiation therapy (IMRT) treatment delivered by linear accelerator (linac) and helical TomoTherapy. Multiple human CT data sets were used to segment critical structures and organs at risk, fused and adjusted to an anthropomorphic phantom. Eighteen contours were designated for thermoluminescent dosimeter (TLD) placement. Following the RTOG IMRT Protocol 0522, treatment of the primary tumor and involved nodes (PTV70) and subclinical disease sites (PTV56) was planned utilizing IMRT to 70 Gy and 56 Gy. Clinically acceptable treatment plans were produced for linac and TomoTherapy treatments. TLDs were placed and each treatment plan was delivered to the anthropomorphic phantom four times. Within 2.5 cm (one helical TomoTherapy field width) superior and inferior to the field edges, normal tissue doses were on average 45% lower using linear accelerator. Beyond 2.5 cm, the helical TomoTherapy normal tissue dose was an average of 52% lower. The majority of points proved to be statistically different using the Student's t‐test with p<0.05. Using one method of calculation, probability of a secondary malignancy was 5.88% for the linear accelerator and 4.08% for helical TomoTherapy. Helical TomoTherapy delivers more dose than a linac immediately above and below the treatment field, contributing to the higher peripheral doses adjacent to the field. At distances beyond one field width (where leakage is dominant), helical TomoTherapy doses are lower than linear accelerator doses. PACS number: 87.50.cm Dosimetry/exposure assessment

  11. SU-E-T-436: Accelerated Gated IMRT: A Feasibility Study for Lung Cancer Patients

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Gilles, M; Boussion, N; Visvikis, D

    Purpose: To evaluate the feasibility of delivering a gated Intensity Modulated Radiotherapy (IMRT) treatment using multiple respiratory phases in order to account for all anatomic changes during free breathing and accelerate the gated treatment without increasing the dose per fraction. Methods: For 7 patients with lung cancer, IMRT treatment plans were generated on a full inspiration (FI) Computed Tomography (CT) and a Mid Intensity Position (MIP) CT. Moreover, in order to achieve an accelerated gated IMRT, multiple respiratory phase plans were calculated: 2-phase plans including the FI and the full expiration phases, and 3-phase plans by adding the mid-inspiration phase.more » In order to assess the tolerance limits, plans' doses were registered and summed to the FI-based plan. Mean dose received by Organs at Risk (OARs) and target volumes were used to compare obtained plans. Results: The mean dose differences between the FI plans and the multi-phase plans never exceeded 0.4 Gy (Fig. 1). Concerning the clinical target volume these differences were even smaller: less than 0.1 Gy for both the 2-phase and 3-phase plans. Regarding the MIP treatment plan, higher doses in different healthy structures were observed, with a relative mean increase of 0.4 to 1.5 Gy. Finally, compared to the prescribed dose, the FI as well as the multi-phase plans were associated with a mean difference of 0.4 Gy, whereas in the case of MIP a higher mean difference of 0.6 Gy was observed. Conclusion: The doses obtained while planning a multi-phase gated IMRT treatment were within the tolerance limits. Compared to MIP, a better healthy tissue sparing was observed in the case of treatment planning based on one or multiple phases. Future work will consist in testing the multi-phase treatment delivery while accounting for the multileaf collimator speed constraints.« less

  12. Hyperfractionated Accelerated Radiotherapy (HART) for Anaplastic Thyroid Carcinoma: Toxicity and Survival Analysis

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Dandekar, Prasad; Harmer, Clive; Barbachano, Yolanda

    2009-06-01

    Purpose: Anaplastic thyroid carcinoma (ATC) is one of the most aggressive cancers, and the current protocol of hyperfractionated accelerated radiotherapy was initiated to improve survival while limiting toxicities. Methods and Materials: All patients with ATC from 1991 to 2002 were accrued and received megavoltage radiotherapy from the mastoid processes to the carina up to 60 Gy in twice-daily fractions of 1.8 and 2 Gy, 6 hours apart. Results: Thirty-one patients were accrued with a median age of 69 years, and 55% were women. Debulking was performed in 26%, and total thyroidectomy, in 6%, whereas 68% received radical radiotherapy alone. Localmore » control data were available for 27 patients: 22% had a complete response, 26% had a partial response, 15% showed progressive disease, and 37% showed static disease. Median overall survival for all 31 patients was 70 days (95% confidence interval, 40-99). There was no significant difference in median survival between patients younger (70 days) and older than 70 years (42 days), between men (70 days) and women (49days), and between patients receiving postoperative radiotherapy (77 days) and radical radiotherapy alone (35 days). Grade III or higher skin erythema was seen in 56% patients; desquamation in 21%; dysphagia in 74%; and esophagitis in 79%. Conclusion: The current protocol failed to offer a significant survival benefit, was associated with severe toxicities, and thus was discontinued. There is a suggestion that younger patients with operable disease have longer survival, but this would require a larger study to confirm it.« less

  13. Comparison of proton beam radiotherapy and hyper-fractionated accelerated chemoradiotherapy for locally advanced pancreatic cancer.

    PubMed

    Maemura, Kosei; Mataki, Yuko; Kurahara, Hiroshi; Kawasaki, Yota; Iino, Satoshi; Sakoda, Masahiko; Ueno, Shinichi; Arimura, Takeshi; Higashi, Ryutaro; Yoshiura, Takashi; Shinchi, Hiroyuki; Natsugoe, Shoji

    We compared the clinical outcomes of proton beam radiotherapy (PBRT) and those of conventional chemoradiotherapy via hyper-fractionated acceleration radiotherapy (HART) after induction chemotherapy in patients with locally advanced pancreatic cancer (LAPC). Twenty-five consecutive patients with LAPC received induction chemotherapy comprising gemcitabine and S-1 before radiotherapy. Of these, 15 and 10 were enrolled in the HART and PBRT groups, respectively. Moderate hematological toxicities were observed only in the HART group, whereas two patients in the PBRT group developed duodenal ulcers. All patients underwent scheduled radiotherapy, with overall disease control rates of 93% and 80% in the HART and PBRT groups, respectively. Local progression was observed in 60% and 40% of patients in the HART and PBRT groups, respectively. However, there was no statistical significance between the two groups regarding the median time to progression (15.4 months in both) and the median overall survival (23.4 v.s. 22.3 months). PBRT was feasible and tolerable, and scheduled protocols could be completed with careful attention to gastrointestinal ulcers. Despite the lower incidence of local recurrence, PBRT did not yield obvious progression control and survival benefits relative to conventional chemoradiotherapy. Copyright © 2017 IAP and EPC. Published by Elsevier B.V. All rights reserved.

  14. Dosimetric comparison of 3D conformal, IMRT, and V-MAT techniques for accelerated partial-breast irradiation (APBI)

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Qiu, Jian-Jian; Department of Radiation Oncology, Fudan University Shanghai Cancer Center, Shanghai; Department of Oncology, Shanghai Medical College, Fudan University, Shanghai

    2014-07-01

    The purpose is to dosimetrically compare the following 3 delivery techniques: 3-dimensional conformal radiation therapy (3D-CRT), intensity-modulated arc therapy (IMRT), and volumetric-modulated arc therapy (V-MAT) in the treatment of accelerated partial-breast irradiation (APBI). Overall, 16 patients with T1/2N0 breast cancer were treated with 3D-CRT (multiple, noncoplanar photon fields) on the RTOG 0413 partial-breast trial. These cases were subsequently replanned using static gantry IMRT and V-MAT technology to understand dosimetric differences among these 3 techniques. Several dosimetric parameters were used in plan quality evaluation, including dose conformity index (CI) and dose-volume histogram analysis of normal tissue coverage. Quality assurance studies includingmore » gamma analysis were performed to compare the measured and calculated dose distributions. The IMRT and V-MAT plans gave more conformal target dose distributions than the 3D-CRT plans (p < 0.05 in CI). The volume of ipsilateral breast receiving 5 and 10 Gy was significantly less using the V-MAT technique than with either 3D-CRT or IMRT (p < 0.05). The maximum lung dose and the ipsilateral lung volume receiving 10 (V{sub 10}) or 20 Gy (V{sub 20}) were significantly less with both V-MAT and IMRT (p < 0.05). The IMRT technique was superior to 3D-CRT and V-MAT of low dose distributions in ipsilateral lung (p < 0.05 in V{sub 5} and D{sub 5}). The total mean monitor units (MUs) for V-MAT (621.0 ± 111.9) were 12.2% less than those for 3D-CRT (707.3 ± 130.9) and 46.5% less than those for IMRT (1161.4 ± 315.6) (p < 0.05). The average machine delivery time was 1.5 ± 0.2 minutes for the V-MAT plans, 7.0 ± 1.6 minutes for the 3D-CRT plans, and 11.5 ± 1.9 minutes for the IMRT plans, demonstrating much less delivery time for V-MAT. Based on this preliminary study, V-MAT and IMRT techniques offer improved dose conformity as compared with 3D-CRT techniques without increasing dose to the ipsilateral

  15. Accelerated iterative beam angle selection in IMRT

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Bangert, Mark, E-mail: m.bangert@dkfz.de; Unkelbach, Jan

    2016-03-15

    Purpose: Iterative methods for beam angle selection (BAS) for intensity-modulated radiation therapy (IMRT) planning sequentially construct a beneficial ensemble of beam directions. In a naïve implementation, the nth beam is selected by adding beam orientations one-by-one from a discrete set of candidates to an existing ensemble of (n − 1) beams. The best beam orientation is identified in a time consuming process by solving the fluence map optimization (FMO) problem for every candidate beam and selecting the beam that yields the largest improvement to the objective function value. This paper evaluates two alternative methods to accelerate iterative BAS based onmore » surrogates for the FMO objective function value. Methods: We suggest to select candidate beams not based on the FMO objective function value after convergence but (1) based on the objective function value after five FMO iterations of a gradient based algorithm and (2) based on a projected gradient of the FMO problem in the first iteration. The performance of the objective function surrogates is evaluated based on the resulting objective function values and dose statistics in a treatment planning study comprising three intracranial, three pancreas, and three prostate cases. Furthermore, iterative BAS is evaluated for an application in which a small number of noncoplanar beams complement a set of coplanar beam orientations. This scenario is of practical interest as noncoplanar setups may require additional attention of the treatment personnel for every couch rotation. Results: Iterative BAS relying on objective function surrogates yields similar results compared to naïve BAS with regard to the objective function values and dose statistics. At the same time, early stopping of the FMO and using the projected gradient during the first iteration enable reductions in computation time by approximately one to two orders of magnitude. With regard to the clinical delivery of noncoplanar IMRT treatments, we

  16. Accelerated iterative beam angle selection in IMRT.

    PubMed

    Bangert, Mark; Unkelbach, Jan

    2016-03-01

    Iterative methods for beam angle selection (BAS) for intensity-modulated radiation therapy (IMRT) planning sequentially construct a beneficial ensemble of beam directions. In a naïve implementation, the nth beam is selected by adding beam orientations one-by-one from a discrete set of candidates to an existing ensemble of (n - 1) beams. The best beam orientation is identified in a time consuming process by solving the fluence map optimization (FMO) problem for every candidate beam and selecting the beam that yields the largest improvement to the objective function value. This paper evaluates two alternative methods to accelerate iterative BAS based on surrogates for the FMO objective function value. We suggest to select candidate beams not based on the FMO objective function value after convergence but (1) based on the objective function value after five FMO iterations of a gradient based algorithm and (2) based on a projected gradient of the FMO problem in the first iteration. The performance of the objective function surrogates is evaluated based on the resulting objective function values and dose statistics in a treatment planning study comprising three intracranial, three pancreas, and three prostate cases. Furthermore, iterative BAS is evaluated for an application in which a small number of noncoplanar beams complement a set of coplanar beam orientations. This scenario is of practical interest as noncoplanar setups may require additional attention of the treatment personnel for every couch rotation. Iterative BAS relying on objective function surrogates yields similar results compared to naïve BAS with regard to the objective function values and dose statistics. At the same time, early stopping of the FMO and using the projected gradient during the first iteration enable reductions in computation time by approximately one to two orders of magnitude. With regard to the clinical delivery of noncoplanar IMRT treatments, we could show that optimized beam

  17. HI-CHART: a phase I/II study on the feasibility of high-dose continuous hyperfractionated accelerated radiotherapy in patients with inoperable non-small-cell lung cancer.

    PubMed

    De Ruysscher, Dirk; Wanders, Rinus; van Haren, Erik; Hochstenbag, Monique; Geraedts, Wiel; Pitz, Cordula; Simons, Jean; Boersma, Liesbeth; Verschueren, Tom; Minken, Andre; Bentzen, Søren M; Lambin, Philippe

    2008-05-01

    To determine the feasibility of high-dose continuous hyperfractionated accelerated radiotherapy in patients with inoperable non-small-cell lung cancer (NSCLC). In a prospective, Phase I/II study, according to the risk for radiation pneumonitis, three risk groups were defined: V(20) <25%, V(20) 25-37%, and V(20) >37%. The dose was administered in three steps from 61.2 Gy/34 fractions/23 days to 64.8 Gy/36 fractions/24 days to 68.40 Gy/38 fractions/25 days (1.8 Gy b.i.d. with 8-h interval), using a three-dimensional conformal technique. Only the mediastinal lymph node areas that were positive on the pretreatment (18)F-deoxy-D-glucose positron emission tomography scan were included in the target volume. The primary endpoint was toxicity. A total of 48 Stage I-IIIB patients were included. In all risk groups, 68.40 Gy/38 fractions/25 days could be administered. Maximal toxicity according to the risk groups was as follows: V(20) <25% (n = 35): 1 Grade 4 (G4) lung and 1 G3 reversible esophageal toxicity; V(20) 35-37% (n = 12): 1 G5 lung and 1 G3 reversible esophageal toxicity. For the whole group, local tumor recurrence occurred in 25% (95% confidence interval 14%-40%) of the patients, with 1 of 48 (2.1%; upper one-sided 95% confidence limit 9.5%) having an isolated nodal recurrence. The median actuarial overall survival was 20 months, with a 2-year survival rate of 36%. High-dose continuous hyperfractionated accelerated radiotherapy up to a dose of 68.40 Gy/38 fractions/25 days (a biologic equivalent of approximately 80 Gy when delivered in conventional fractionation) in patients with inoperable NSCLC and a V(20) up to 37% is feasible.

  18. Intensity-Modulated Radiation Therapy (IMRT)

    MedlinePlus

    ... specialized training in the field of radiation oncology physics, ensures the linear accelerator delivers the precise radiation ... critical normal structures, as well as the patient's health. Typically, patients are scheduled for IMRT sessions five ...

  19. Hyperfractionated accelerated radiotherapy with concomitant integrated boost of 70-75 Gy in 5 weeks for advanced head and neck cancer. A phase I dose escalation study.

    PubMed

    Cvek, J; Kubes, J; Skacelikova, E; Otahal, B; Kominek, P; Halamka, M; Feltl, D

    2012-08-01

    The present study was performed to evaluate the feasibility of a new, 5-week regimen of 70-75 Gy hyperfractionated accelerated radiotherapy with concomitant integrated boost (HARTCIB) for locally advanced, inoperable head and neck cancer. A total of 39 patients with very advanced, stage IV nonmetastatic head and neck squamous cell carcinoma (median gross tumor volume 72 ml) were included in this phase I dose escalation study. A total of 50 fractions intensity-modulated radiotherapy (IMRT) were administered twice daily over 5 weeks. Prescribed total dose/dose per fraction for planning target volume (PTV(tumor)) were 70 Gy in 1.4 Gy fractions, 72.5 Gy in 1.45 Gy fractions, and 75 Gy in 1.5 Gy fractions for 10, 13, and 16 patients, respectively. Uninvolved lymphatic nodes (PTV(uninvolved)) were irradiated with 55 Gy in 1.1 Gy fractions using the concomitant integrated boost. Acute toxicity was evaluated according to the RTOG/EORTC scale; the incidence of grade 3 mucositis was 51% in the oral cavity/pharynx and 0% in skin and the recovery time was ≤ 9 weeks for all patients. Late toxicity was evaluated in patients in complete remission according to the RTOG/EORTC scale. No grade 3/4 late toxicity was observed. The 1-year locoregional progression-free survival was 50% and overall survival was 55%. HARTCIB (75 Gy in 5 weeks) is feasible for patients deemed unsuitable for chemoradiation. Acute toxicity was lower than predicted from radiobiological models; duration of dysphagia and confluent mucositis were particularly short. Better conformity of radiotherapy allows the use of more intensive altered fractionation schedules compared with older studies. These results suggest that further dose escalation might be possible when highly conformal techniques (e.g., stereotactic radiotherapy) are used.

  20. Angiosarcoma after breast-conserving therapy: long-term outcomes with hyperfractionated radiotherapy.

    PubMed

    Palta, Manisha; Morris, Christopher G; Grobmyer, Stephen R; Copeland, Edward M; Mendenhall, Nancy P

    2010-04-15

    With breast-conserving therapy (BCT) as the standard of care for patients with noninvasive and early stage invasive breast cancer, a small incidence of post-BCT angiosarcoma has emerged. The majority of therapeutic interventions have been unsuccessful. To the authors' knowledge, there is no consensus in the medical literature to date regarding the treatment of this malignancy. The current study was conducted to report the long-term outcomes of a novel approach using hyperfractionated and accelerated radiotherapy (HART) for angiosarcoma developing after BCT. The authors retrospectively reviewed the outcomes of 14 patients treated with HART with or without surgery at the University of Florida between November 1997 and March 2006 for angiosarcoma that developed after BCT. At the time of last follow-up, 9 patients had remained continuously without evidence of disease for a median of 61 months after HART (range, 36-127 months). Five patients had further manifestations of angiosarcoma after HART at a median of 1 month (range, 1-28 months): 3 with progressive pulmonary and/or mediastinal disease that was likely present before HART and 2 with local or regional disease extension. Progression-free survival rates for the 14 patients at 2 years and 5 years were 71% and 64%, respectively. The overall and cause-specific survival rates were both 86% at 2 years and 5 years. To the best of the authors' knowledge, HART with or without subsequent surgery, as documented in the current series, is the first approach to provide a high rate of local control, disease-free survival, and overall survival after the development of post-BCT angiosarcoma. The authors believe the success noted with this approach is related to both the hyperfractionation and acceleration of the RT. (c) 2010 American Cancer Society.

  1. Combined treatment of anaplastic thyroid carcinoma with surgery, chemotherapy, and hyperfractionated accelerated external radiotherapy

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    De Crevoisier, Renaud; Baudin, Eric; Bachelot, Anne

    Purpose: To analyze a prospective protocol combining surgery, chemotherapy (CT), and hyperfractionated accelerated radiotherapy (RT) in anaplastic thyroid carcinoma. Methods and materials: Thirty anaplastic thyroid carcinoma patients (mean age, 59 years) were treated during 1990-2000. Tumor extended beyond the capsule gland in 26 patients, with tracheal extension in 8. Lymph node metastases were present in 18 patients and lung metastases in 6. Surgery was performed before RT-CT in 20 patients and afterwards in 4. Two cycles of doxorubicin (60 mg/m{sup 2}) and cisplatin (120 mg/m{sup 2}) were delivered before RT and four cycles after RT. RT consisted of two dailymore » fractions of 1.25 Gy, 5 days per week to a total dose of 40 Gy to the cervical lymph node areas and the superior mediastinum. Results: Acute toxicity (World Health Organization criteria) was Grade 3 or 4 pharyngoesophagitis in 10 patients; Grade 4 neutropenia in 21, with infection in 13; and Grade 3 or 4 anemia and thrombopenia in 8 and 4, respectively. At the end of the treatment, a complete local response was observed in 19 patients. With a median follow-up of 45 months (range, 12-78 months), 7 patients were alive in complete remission, of whom 6 had initially received a complete tumor resection. Overall survival rate at 3 years was 27% (95% confidence interval 10-44%) and median survival 10 months. In multivariate analysis, tracheal extension and macroscopic complete tumor resection were significant factors in overall survival. Death was related to local progression in 5% of patients, to distant metastases in 68%, and to both in 27%. Conclusions: Main toxicity was hematologic. High long-term survival was obtained when RT-CT was given after complete surgery. This protocol avoided local tumor progression, and death was mainly caused by distant metastases.« less

  2. Intensified hyperfractionated accelerated radiotherapy limits the additional benefit of simultaneous chemotherapy--results of a multicentric randomized German trial in advanced head-and-neck cancer.

    PubMed

    Staar, S; Rudat, V; Stuetzer, H; Dietz, A; Volling, P; Schroeder, M; Flentje, M; Eckel, H E; Mueller, R P

    2001-08-01

    To demonstrate the efficacy of radiochemotherapy (RCT) as the first choice of treatment for advanced unresectable head-and-neck cancer. To prove an expected benefit of simultaneously given chemotherapy, a two-arm randomized study with hyperfractionated accelerated radiochemotherapy (HF-ACC-RCT) vs. hyperfractionated accelerated radiotherapy (HF-ACC-RT) was initiated. The primary endpoint was 1-year survival with local control (SLC). Patients with Stage III and IV (UICC) unresectable oro- and hypopharyngeal carcinomas were randomized for HF-ACC-RCT with 2 cycles of 5-FU (600 mg/m(2)/day)/carboplatinum (70 mg/m(2)) on days 1--5 and 29--33 (arm A) or HF-ACC-RT alone (arm B). In both arms, there was a second randomization for testing the effect of prophylactically given G-CSF (263 microg, days 15--19) on mucosal toxicity. Total RT dose in both arms was 69.9 Gy in 38 days, with a concomitant boost regimen (weeks 1--3: 1.8 Gy/day, weeks 4 and 5: b.i.d. RT with 1.8 Gy/1.5 Gy). Between July 1995 and May 1999, 263 patients were randomized (median age 56 years; 96% Stage IV tumors, 4% Stage III tumors). This analysis is based on 240 patients: 113 patients with RCT and 127 patients with RT, qualified for protocol and starting treatment. There were 178 oropharyngeal and 62 hypopharyngeal carcinomas. Treatment was tolerable in both arms, with a higher mucosal toxicity after RCT. Restaging showed comparable nonsignificant different CR + PR rates of 92.4% after RCT and 87.9% after RT (p = 0.29). After a median observed time of 22.3 months, l- and 2-year local-regional control (LRC) rates were 69% and 51% after RCT and 58% and 45% after RT (p = 0.14). There was a significantly better 1-year SLC after RCT (58%) compared with RT (44%, p = 0.05). Patients with oropharyngeal carcinomas showed significantly better SLC after RCT (60%) vs. RT (40%, p = 0.01); the smaller group of hypopharyngeal carcinomas had no statistical benefit of RCT (p = 0.84). For both tumor locations

  3. A meta-analysis of hyperfractionated and accelerated radiotherapy and combined chemotherapy and radiotherapy regimens in unresected locally advanced squamous cell carcinoma of the head and neck

    PubMed Central

    Budach, W; Hehr, T; Budach, V; Belka, C; Dietz, K

    2006-01-01

    Background Former meta-analyses have shown a survival benefit for the addition of chemotherapy (CHX) to radiotherapy (RT) and to some extent also for the use of hyperfractionated radiation therapy (HFRT) and accelerated radiation therapy (AFRT) in locally advanced squamous cell carcinoma (SCC) of the head and neck. However, the publication of new studies and the fact that many older studies that were included in these former meta-analyses used obsolete radiation doses, CHX schedules or study designs prompted us to carry out a new analysis using strict inclusion criteria. Methods Randomised trials testing curatively intended RT (≥60 Gy in >4 weeks/>50 Gy in <4 weeks) on SCC of the oral cavity, oropharynx, hypopharynx, and larynx published as full paper or in abstract form between 1975 and 2003 were eligible. Trials comparing RT alone with concurrent or alternating chemoradiation (5-fluorouracil (5-FU), cisplatin, carboplatin, mitomycin C) were analyzed according to the employed radiation schedule and the used CHX regimen. Studies comparing conventionally fractionated radiotherapy (CFRT) with either HFRT or AFRT without CHX were separately examined. End point of the meta-analysis was overall survival. Results Thirty-two trials with a total of 10 225 patients were included into the meta-analysis. An overall survival benefit of 12.0 months was observed for the addition of simultaneous CHX to either CFRT or HFRT/AFRT (p < 0.001). Separate analyses by cytostatic drug indicate a prolongation of survival of 24.0 months, 16.8 months, 6.7 months, and 4.0 months, respectively, for the simultaneous administration of 5-FU, cisplatin-based, carboplatin-based, and mitomycin C-based CHX to RT (each p < 0.01). Whereas no significant gain in overall survival was observed for AFRT in comparison to CFRT, a substantial prolongation of median survival (14.2 months, p < 0.001) was seen for HFRT compared to CFRT (both without CHX). Conclusion RT combined with simultaneous 5-FU

  4. Preventing radiation retinopathy with hyperfractionation

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Monroe, Alan T.; Bhandare, Niranjan; Morris, Christopher G.

    2005-03-01

    Purpose: The purpose of this study was to determine factors associated with the development of radiation retinopathy in a large series of patients with head-and-neck cancer. In particular, we addressed whether the use of hyperfractionated radiation therapy was effective in reducing the risk of retinopathy. Methods and materials: One hundred eighty-six patients received a significant dose to the retina as part of curative radiotherapy. Primary sites included: nasopharynx, 46; paranasal sinus, 64; nasal cavity, 69; and palate, 7. Prescription doses varied depending on primary site and histology. Hyperfractionated (twice-daily) radiation was delivered to 42% of the patients in this study,more » typically at 1.10 to 1.20 Gy per fraction. The remainder were treated once-daily. Retinal doses were determined from computerized dosimetry plans when available. For all other patients, retinal doses were retrospectively calculated using reconstructed off-axis dosimetry taken from contours through the center of the globes. Retinal dose was defined as the minimum dose received by at least 25% of the globe. The median retinal dose was 56.85 Gy. Patients were followed for a median of 7.6 years. Results: Thirty-one eyes in 30 patients developed radiation retinopathy, resulting in monocular blindness in 25, bilateral blindness in 1, and decreased visual acuity in 4. The median time to the diagnosis of retinopathy was 2.6 years (range, 11 months to 5.3 years). The actuarial incidence of developing radiation retinopathy was 20% at both 5 and 10 years. The incidence of developing ipsilateral blindness due to retinopathy was 16% at 5 years and 17% at 10 years. Site-specific incidences varied considerably, with ethmoid sinus (9 of 25, 36%), nasal cavity (13 of 69, 19%), and maxillary sinus (6 of 35, 17%) being the most common sites associated with radiation retinopathy. Three of 72 patients (4%) receiving retinal doses less than 50 Gy developed retinopathy. Higher retinal doses

  5. Randomized phase III trial of concurrent chemoradiotherapy vs accelerated hyperfractionation radiotherapy in locally advanced head and neck cancer

    PubMed Central

    Chitapanarux, Imjai; Tharavichitkul, Ekkasit; Kamnerdsupaphon, Pimkhuan; Pukanhapan, Nantaka; Vongtama, Roy

    2013-01-01

    The aim of this study was to compare the efficacy and safety of concurrent chemoradiotherapy (CCRT) vs accelerated hyperfractionation with concomitant boost (CCB) as a primary treatment for patients with Stage III–IV squamous cell carcinoma of head and neck (SCCHN). A total of 85 non-metastatic advanced SCCHN patients were accrued from January 2003 to December 2007. Of these, 48 and 37 patients received CCRT and CCB, respectively. The patients were randomized to receive either three cycles of carboplatin and 5-fluorouracil plus conventional radiotherapy (CCRT, 66 Gy in 6.5 weeks) or hybrid accelerated radiotherapy (CCB, 70 Gy in 6 weeks). The primary endpoint was determined by locoregional control rate. The secondary endpoints were overall survival and toxicity. With a median follow-up of 43 months (range, 3–102), the 5-year locoregional control rate was 69.6% in the CCRT arm vs 55.0% in the CCB arm (P = 0.184). The 5-year overall survival rate was marginally significantly different (P = 0.05): 76.1% in the CCRT arm vs 63.5% in the CCB arm. Radiotherapy treatment interruptions of more than three days were 60.4% and 40.5% in the CCRT arm and CCB arm, respectively. The median total treatment time was 55.5 days in the CCRT arm and 49 days in the CCB arm. The rate of Grade 3–4 acute mucositis was significantly higher in the CCB arm (67.6% vs 41.7%, P = 0.01), but no high grade hematologic toxicities were found in the CCB arm (27.2% vs 0%). CCRT has shown a trend of improving outcome over CCB irradiation in locoregionally advanced head and neck cancer. PMID:23740894

  6. Long-term outcomes of late course accelerated hyper-fractionated radiotherapy for localized esophageal carcinoma in Mainland China: a meta-analysis.

    PubMed

    Zhang, Y W; Chen, L; Bai, Y; Zheng, X

    2011-09-01

    Published data on the long-term survival results of patients with localized esophageal carcinoma receiving late course accelerated hyper-fractionated radiotherapy (LCAF RT) versus conventional fractionated radiotherapy (CF RT) are inconclusive. In order to derive a more precise estimation of the both treatment-regimes, a meta-analysis based on systematic review of published articles was performed. A meta-analysis was performed using trials identified through Pubmed and Chinese national knowledge infrastructure. Results in 5-year survival and 5-year local control were collected from randomized trials comparing LCAF RT with CF RT. Review Manager (The Cochrane Collaboration, Oxford, England) and Stata software (Stata Corporation, College Station, TX, USA) were used for data management. A total of 11 trials were involved in this analysis with 572 cases and 567 controls. Our results showed that LCAF RT, compared with CF RT, significantly improved the 5-year survival (odds ratio [OR]= 2.93, 95% confidence interval [CI]: 2.15-4.00, P < 0.00001) and 5-year local control (OR = 3.96, 95% CI: 2.91-5.38, P < 0.00001). LCAF RT was more therapeutically beneficial than CF RT in the localized esophageal carcinoma. © 2011 Copyright the Authors. Journal compilation © 2011, Wiley Periodicals, Inc. and the International Society for Diseases of the Esophagus.

  7. Compensators: An alternative IMRT delivery technique

    PubMed Central

    Chang, Sha X.; Cullip, Timothy J.; Deschesne, Katharin M.; Miller, Elizabeth P.; Rosenman, Julian G.

    2004-01-01

    Seven years of experience in compensator intensity‐modulated radiotherapy (IMRT) clinical implementation are presented. An inverse planning dose optimization algorithm was used to generate intensity modulation maps, which were delivered via either the compensator or segmental multileaf collimator (MLC) IMRT techniques. The in‐house developed compensator‐IMRT technique is presented with the focus on several design issues. The dosimetry of the delivery techniques was analyzed for several clinical cases. The treatment time for both delivery techniques on Siemens accelerators was retrospectively analyzed based on the electronic treatment record in LANTIS for 95 patients. We found that the compensator technique consistently took noticeably less time for treatment of equal numbers of fields compared to the segmental technique. The typical time needed to fabricate a compensator was 13 min, 3 min of which was manual processing. More than 80% of the approximately 700 compensators evaluated had a maximum deviation of less than 5% from the calculation in intensity profile. Seventy‐two percent of the patient treatment dosimetry measurements for 340 patients have an error of no more than 5%. The pros and cons of different IMRT compensator materials are also discussed. Our experience shows that the compensator‐IMRT technique offers robustness, excellent intensity modulation resolution, high treatment delivery efficiency, simple fabrication and quality assurance (QA) procedures, and the flexibility to be used in any teletherapy unit. PACS numbers: 87.53Mr, 87.53Tf PMID:15753937

  8. SU-E-T-217: Comprehensive Dosimetric Evaluation On 3D-CRT, IMRT and Non-Coplanar Arc Treatment for Prone Accelerated Partial Breast Irradiation (APBI)

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Chiu, T; Yan, Y; Ramirez, E

    2015-06-15

    Purpose: Accelerated partial breast irradiation (APBI) is an effective treatment for early stage breast-cancer. Irradiation in a prone position can mitigate breast motion and spare heart and lung. In this study, a comprehensive study is performed to evaluate various treatment techniques for prone APBI treatment including: 3D-CRT, IMRT, co-planar and non-coplanar partial arcs treatment. Methods: In this treatment planning study, a left breast patient treated in prone position in our clinic was imported into Varian Eclipse TPS. Six beams tangential to chest wall were used in both 3D-CRT and IMRT plans. These six beams were coplanar in a transactional planemore » achieved by both gantry and couch rotation. A 60-beam IMRT plan was also created to explore the maximum benefit of co-planar IMRT. Within deliverable couch rotation range (±30°), partial arc treatment plans with one and up to ten couch positions were generated for comparison. For each plan, 30Gy in 6 fractions was prescribed to 95% PTV volume. Critical dosimetric parameters, such as conformity index, mean, maximum, and volume dose of organ at risk, are evaluated. Results: The conformity indexes (CI) are 3.53, 3.17, 2.21 and 1.08 respectively to 3D-CRT, 6-beam IMRT, 60-beam IMRT, and two-partial-arcs coplanar plans. However, arc plans increase heart dose. CI for non-coplanar arc plans decreases from 1.19 to 1.10 when increases couch positions. Maximum dose in ipsilateral lung (1.98 to 1.13 Gy), and heart (0.62 to 0.43 Gy) are steadily decreased with the increased number of non-coplanar arcs. Conclusions: The dosimetric evaluation results show that partial arc plans have improved CIs compared to conventional 3D-CRT and IMRT plans. Increasing number of partial arcs decreases lung and heart dose. The dosimetric benefit obtained from non-coplanar arcs should be considered with treatment delivery time.« less

  9. Impact of Adding Concomitant Chemotherapy to Hyperfractionated Accelerated Radiotherapy for Advanced Head-and-Neck Squamous Cell Carcinoma

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Nuyts, Sandra; Dirix, Piet; Clement, Paul M.J.

    2009-03-15

    Purpose: To evaluate the feasibility and efficacy of a hyperfractionated accelerated radiotherapy (RT) schedule combined with concomitant chemotherapy (Cx) in patients with locally advanced head-and-neck squamous cell carcinoma. Methods and Materials: Between 2004 and 2007, a total of 90 patients with locoregionally advanced head-and-neck squamous cell carcinoma underwent irradiation according to a hybrid fractionation schedule consisting of 20 fractions of 2 Gy (once daily) followed by 20 fractions of 1.6 Gy (twice daily) to a total dose of 72 Gy. Concomitant Cx (cisplatinum 100 mg/m{sup 2}) was administered at the start of Weeks 1 and 4. Treatment outcome and toxicitymore » were retrospectively compared with a previous patient group (n = 73) treated with the same schedule, but without concomitant Cx, between 2001 and 2004. Results: The locoregional control (LRC) rate was 70% after 2 years. Two-year overall and 2-year disease-free survival rates were 74% and 60%, respectively. In comparison with the RT-only group, an improvement of 15% in both LRC (p = 0.03) and overall survival (p = 0.09) was observed. All patients were treated to full radiation dose according to protocol, although the Cx schedule had to be adjusted in 12 patients. No acute Grade 4 or 5 toxicity was seen, but incidences of Grade 3 acute mucositis (74.5% vs. 50.7%; p = 0.002) and dysphagia (82.2% vs. 47.9%; p < 0.001) were significantly higher in the chemoradiotherapy group compared with patients treated with RT alone. Conclusion: With this chemoradiotherapy regimen, excellent LRC and survival rates were achieved, with acceptable acute toxicity.« less

  10. High Dose Hyperfractionated Radiotherapy for Adults with Glioblastomas

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Koukourakis, Michael; Scarlatos, John; Yiannakakis, Dimitrios

    2015-01-15

    From 1989 to 1991, 27 patients with glioblastoma multiforme or anaplastic astrocytoma of the brain were treated with radiotherapy. Fifteen of twenty-seven patients were treated through limited volume fields, with a thrice-a-day (1.1 Gy/f) or twice-a-day (1.4 Gy/f) hyperfractionated regimen to a total physical dose of 62–92 Gy (median dose 76 Gy). The remaining 12 were treated with whole brain irradiation (40 Gy of total conventionally fractionated dose) and a localised boost to a total dose of 60 Gy. The hyperfractionated regimen was well tolerated and there was no sign of increased brain oedema to indicate the insertion of amore » split. Of six patients who received a NTD10 (normalised total dose for α/β =10) higher than 71 Gy, five showed CR (83% CR rate) versus three of 21 patients who received a lower NTD10 (14% CR rate). For 13 patients who received a NTD10 higher than 66 Gy, the 18-months survival was 61% (8/13) versus 28% (4/14) for 14 patients who received a NTD10 less than 66 Gy. As far as the late morbidity is concerned, of six patients treated with 76-92 Gy of physical dose, none died because of radiation-induced brain necrosis within 18-42 months of follow-up, and three of them are without evidence of disease 18-31 months after the end of radiation treatment. None of our 15 patients who received less than whole brain irradiation relapsed outside the radiation portals. The present study strongly suggests the use of limited volume hyperfractionated radiotherapy schemes, so as to increase the local tumor dose (NTD10) to values higher than 79 Gy, at the same time keeping the NTD2 (NTD for α/β = 2) below 68 Gy.« less

  11. Phase II Trial of Hyperfractionated Intensity-Modulated Radiation Therapy and Concurrent Weekly Cisplatin for Stage III and IVa Head-and-Neck Cancer

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Maguire, Patrick D., E-mail: pmaguire@nhroc.co; Papagikos, Michael; Hamann, Sue

    2011-03-15

    Purpose: To investigate a novel chemoradiation regimen designed to maximize locoregional control (LRC) and minimize toxicity for patients with advanced head-and-neck squamous cell carcinoma (HNSCC). Methods and Materials: Patients received hyperfractionated intensity modulated radiation therapy (HIMRT) in 1.25-Gy fractions b.i.d. to 70 Gy to high-risk planning target volume (PTV). Intermediate and low-risk PTVs received 60 Gy and 50 Gy, at 1.07, and 0.89 Gy per fraction, respectively. Concurrent cisplatin 33 mg/m{sup 2}/week was started Week 1. Patients completed the Quality of Life Radiation Therapy Instrument pretreatment (PRE), at end of treatment (EOT), and at 1, 3, 6, 9, and 12more » months. Overall survival (OS), progression-free (PFS), LRC, and toxicities were assessed. Results: Of 39 patients, 30 (77%) were alive without disease at median follow-up of 37.5 months. Actuarial 3-year OS, PFS, and LRC were 80%, 82%, and 87%, respectively. No failures occurred in the electively irradiated neck and there were no isolated neck failures. Head and neck QOL was significantly worse in 18 of 35 patients (51%): mean 7.8 PRE vs. 3.9 EOT. By month 1, H and N QOL returned near baseline (mean 6.2, SD = 1.7). The most common acute Grade 3+ toxicities were mucositis (38%), fatigue (28%), dysphagia (28%), and leukopenia (26%). Conclusions: Hyperfractionated IMRT with low-dose weekly cisplatin resulted in good LRC with acceptable toxicity and QOL. Lack of elective nodal failures despite very low dose per fraction has led to an attempt to further minimize toxicity by reducing elective nodal doses in our subsequent protocol.« less

  12. Clinical validation of an in-house EPID dosimetry system for IMRT QA at the Prince of Wales Hospital

    NASA Astrophysics Data System (ADS)

    Tyler, M.; Vial, P.; Metcalfe, P.; Downes, S.

    2013-06-01

    In this study a simple method using standard flood-field corrected Electronic Portal Imaging Device (EPID) images for routine Intensity Modulated Radiation Therapy (IMRT) Quality Assurance (QA) was investigated. The EPID QA system was designed and tested on a Siemens Oncor Impression linear accelerator with an OptiVue 1000ST EPID panel (Siemens Medical Solutions USA, Inc, USA) and an Elekta Axesse linear accelerator with an iViewGT EPID (Elekta AB, Sweden) for 6 and 10 MV IMRT fields with Step-and-Shoot and dynamic-MLC delivery. Two different planning systems were used for patient IMRT field generation for comparison with the measured EPID fluences. All measured IMRT plans had >95% agreement to the planning fluences (using 3 cGy / 3 mm Gamma Criteria) and were comparable to the pass-rates calculated using a 2-D diode array dosimeter.

  13. Head-and-neck IMRT treatments assessed with a Monte Carlo dose calculation engine.

    PubMed

    Seco, J; Adams, E; Bidmead, M; Partridge, M; Verhaegen, F

    2005-03-07

    IMRT is frequently used in the head-and-neck region, which contains materials of widely differing densities (soft tissue, bone, air-cavities). Conventional methods of dose computation for these complex, inhomogeneous IMRT cases involve significant approximations. In the present work, a methodology for the development, commissioning and implementation of a Monte Carlo (MC) dose calculation engine for intensity modulated radiotherapy (MC-IMRT) is proposed which can be used by radiotherapy centres interested in developing MC-IMRT capabilities for research or clinical evaluations. The method proposes three levels for developing, commissioning and maintaining a MC-IMRT dose calculation engine: (a) development of a MC model of the linear accelerator, (b) validation of MC model for IMRT and (c) periodic quality assurance (QA) of the MC-IMRT system. The first step, level (a), in developing an MC-IMRT system is to build a model of the linac that correctly predicts standard open field measurements for percentage depth-dose and off-axis ratios. Validation of MC-IMRT, level (b), can be performed in a rando phantom and in a homogeneous water equivalent phantom. Ultimately, periodic quality assurance of the MC-IMRT system is needed to verify the MC-IMRT dose calculation system, level (c). Once the MC-IMRT dose calculation system is commissioned it can be applied to more complex clinical IMRT treatments. The MC-IMRT system implemented at the Royal Marsden Hospital was used for IMRT calculations for a patient undergoing treatment for primary disease with nodal involvement in the head-and-neck region (primary treated to 65 Gy and nodes to 54 Gy), while sparing the spinal cord, brain stem and parotid glands. Preliminary MC results predict a decrease of approximately 1-2 Gy in the median dose of both the primary tumour and nodal volumes (compared with both pencil beam and collapsed cone). This is possibly due to the large air-cavity (the larynx of the patient) situated in the centre

  14. Efficacy and toxicity profiles of two chemoradiotherapies for stage II laryngeal cancer - a comparison between late course accelerated hyperfractionation (LCAHF) and conventional fractionation (CF).

    PubMed

    Okazaki, Eiichiro; Matsushita, Naoki; Tashiro, Mari; Shimatani, Yasuhiko; Ishii, Kentaro; Hosono, Masako; Oishi, Masahiro; Teranishi, Yuichi; Iguchi, Hiroyoshi; Miki, Yukio

    2017-08-01

    To evaluate the treatment results of late course accelerated hyperfractionation (LCAHF) compared with conventional fractionation (CF) for stage II laryngeal cancer. Fifty-nine consecutive patients treated for stage II laryngeal cancer were retrospectively reviewed. Thirty-two patients underwent LCAHF, twice-daily fractions during the latter half with a total dose of 69 Gy. Twenty-seven patients received CF of 70 Gy. The local control rates (LCRs), overall survival (OS), and disease-specific survival (DSS) at 5 years were 80.6%, 74.0%, and 90.4%, respectively, after LCAHF and 64.7%, 68.2%, and 90.5%, respectively, after CF. There were no significant differences in LCR, OS, and DSS (p = .11, 0.68, and 0.69, respectively). In a small number of patients with supraglottic cancer, LCAHF was associated with a significantly higher LCR at 5 years compared with CF (100% vs. 41.7%; p = .02). This is the first report that compared the results of LCAHF and CF for stage II laryngeal cancer. We could not find significant differences in LCR, DSS, and OS rates between LCAHF and CF groups. Although in a small number of patients with supraglottic cancer, LCAHF may improve the LCR compared with CF.

  15. Continuous 28-day iododeoxyuridine infusion and hyperfractionated accelerated radiotherapy for malignant glioma: a phase I clinical study.

    PubMed

    Schulz, Craig A; Mehta, Minesh P; Badie, Benham; McGinn, Cornelius J; Robins, H Ian; Hayes, Lori; Chappell, Rick; Volkman, Jen; Binger, Kim; Arzoomanian, Rhoda; Simon, Kris; Alberti, Dona; Feierabend, Christine; Tutsch, Kendra D; Kunugi, Keith A; Wilding, George; Kinsella, Timothy J

    2004-07-15

    To investigate the maximal tolerated dose of a continuous 28-day iododeoxyuridine (IUdr) infusion combined with hyperfractionated accelerated radiotherapy (HART); to analyze the percentage of IUdr-thymidine replacement in peripheral granulocytes as a surrogate marker for IUdr incorporation into tumor cells; to measure the steady-state serum IUdr levels; and to assess the feasibility of continuous IUdr infusion and HART in the management of malignant glioma. Patients were required to have biopsy-proven malignant glioma. Patients received 100 (n = 4), 200 (n = 3), 300 (n = 3), 400 (n = 6), 500 (n = 4), 625 (n = 5), or 781 (n = 6) mg/m(2)/d of IUdr by continuous infusion for 28 days. HART was started 7 days after IUdr initiation. The total dose was 70 Gy (1.2 Gy b.i.d. for 25 days with a 10-Gy boost [2.0 Gy for 5 Saturdays]). Weekly assays were performed to determine the percentage of IUdr-DNA replacement in granulocytes and serum IUdr levels using standard high performance liquid chromatography methods. Standard Phase I toxicity methods were used. Between June 1994 and August 1999, 31 patients were enrolled. No patient had Grade 3 or worse HART toxicity. Grade 3 or greater IUdr toxicity predominantly included neutropenia (n = 3), thrombocytopenia (n = 3), and elevated liver function studies (n = 3). The maximal tolerated dose was 625 mg/m(2)/d. Thymidine replacement in the peripheral granulocytes peaked at 3 weeks and increased with the dose (maximal thymidine replacement 4.9%). The steady-state plasma IUdr level increased with the dose (maximum, 1.5 microM). In our study, continuous long-term IUdr i.v. infusion had a maximal tolerated dose of 625 mg/m(2)/d. Granulocyte incorporation data verified the concept that prolonged IUdr infusion results in IUdr-DNA replacement that corresponds to a high degree of cell labeling. IUdr steady-state plasma levels increased with increasing dose and attained levels needed for clinical radiosensitization. Continuous IUdr infusion

  16. Image guided IMRT dosimetry using anatomy specific MOSFET configurations.

    PubMed

    Amin, Md Nurul; Norrlinger, Bern; Heaton, Robert; Islam, Mohammad

    2008-06-23

    We have investigated the feasibility of using a set of multiple MOSFETs in conjunction with the mobile MOSFET wireless dosimetry system, to perform a comprehensive and efficient quality assurance (QA) of IMRT plans. Anatomy specific MOSFET configurations incorporating 5 MOSFETs have been developed for a specially designed IMRT dosimetry phantom. Kilovoltage cone beam computed tomography (kV CBCT) imaging was used to increase the positional precision and accuracy of the detectors and phantom, and so minimize dosimetric uncertainties in high dose gradient regions. The effectiveness of the MOSFET based dose measurements was evaluated by comparing the corresponding doses measured by an ion chamber. For 20 head and neck IMRT plans the agreement between the MOSFET and ionization chamber dose measurements was found to be within -0.26 +/- 0.88% and 0.06 +/- 1.94% (1 sigma) for measurement points in the high dose and low dose respectively. A precision of 1 mm in detector positioning was achieved by using the X-Ray Volume Imaging (XVI) kV CBCT system available with the Elekta Synergy Linear Accelerator. Using the anatomy specific MOSFET configurations, simultaneous measurements were made at five strategically located points covering high dose and low dose regions. The agreement between measurements and calculated doses by the treatment planning system for head and neck and prostate IMRT plans was found to be within 0.47 +/- 2.45%. The results indicate that a cylindrical phantom incorporating multiple MOSFET detectors arranged in an anatomy specific configuration, in conjunction with image guidance, can be utilized to perform a comprehensive and efficient quality assurance of IMRT plans.

  17. A high-speed scintillation-based electronic portal imaging device to quantitatively characterize IMRT delivery.

    PubMed

    Ranade, Manisha K; Lynch, Bart D; Li, Jonathan G; Dempsey, James F

    2006-01-01

    We have developed an electronic portal imaging device (EPID) employing a fast scintillator and a high-speed camera. The device is designed to accurately and independently characterize the fluence delivered by a linear accelerator during intensity modulated radiation therapy (IMRT) with either step-and-shoot or dynamic multileaf collimator (MLC) delivery. Our aim is to accurately obtain the beam shape and fluence of all segments delivered during IMRT, in order to study the nature of discrepancies between the plan and the delivered doses. A commercial high-speed camera was combined with a terbium-doped gadolinium-oxy-sulfide (Gd2O2S:Tb) scintillator to form an EPID for the unaliased capture of two-dimensional fluence distributions of each beam in an IMRT delivery. The high speed EPID was synchronized to the accelerator pulse-forming network and gated to capture every possible pulse emitted from the accelerator, with an approximate frame rate of 360 frames-per-second (fps). A 62-segment beam from a head-and-neck IMRT treatment plan requiring 68 s to deliver was recorded with our high speed EPID producing approximately 6 Gbytes of imaging data. The EPID data were compared with the MLC instruction files and the MLC controller log files. The frames were binned to provide a frame rate of 72 fps with a signal-to-noise ratio that was sufficient to resolve leaf positions and segment fluence. The fractional fluence from the log files and EPID data agreed well. An ambiguity in the motion of the MLC during beam on was resolved. The log files reported leaf motions at the end of 33 of the 42 segments, while the EPID observed leaf motions in only 7 of the 42 segments. The static IMRT segment shapes observed by the high speed EPID were in good agreement with the shapes reported in the log files. The leaf motions observed during beam-on for step-and-shoot delivery were not temporally resolved by the log files.

  18. Image guided IMRT dosimetry using anatomy specific MOSFET configurations

    PubMed Central

    Norrlinger, Bern; Heaton, Robert; Islam, Mohammad

    2008-01-01

    We have investigated the feasibility of using a set of multiple MOSFETs in conjunction with the mobileMOSFET wireless dosimetry system, to perform a comprehensive and efficient quality assurance (QA) of IMRT plans. Anatomy specific MOSFET configurations incorporating 5 MOSFETs have been developed for a specially designed IMRT dosimetry phantom. Kilovoltage cone beam computed tomography (kV CBCT) imaging was used to increase the positional precision and accuracy of the detectors and phantom, and so minimize dosimetric uncertainties in high dose gradient regions. The effectiveness of the MOSFET based dose measurements was evaluated by comparing the corresponding doses measured by an ion chamber. For 20 head and neck IMRT plans the agreement between the MOSFET and ionization chamber dose measurements was found to be within −0.26±0.88% and 0.06±1.94% (1σ) for measurement points in the high dose and low dose respectively. A precision of 1 mm in detector positioning was achieved by using the X‐Ray Volume Imaging (XVI) kV CBCT system available with the Elekta Synergy Linear Accelerator. Using the anatomy specific MOSFET configurations, simultaneous measurements were made at five strategically located points covering high dose and low dose regions. The agreement between measurements and calculated doses by the treatment planning system for head and neck and prostate IMRT plans was found to be within 0.47±2.45%. The results indicate that a cylindrical phantom incorporating multiple MOSFET detectors arranged in an anatomy specific configuration, in conjunction with image guidance, can be utilized to perform a comprehensive and efficient quality assurance of IMRT plans. PACS number: 87.55.Qr

  19. Hyperfractionated Accelerated Radiation Therapy (HART) of 70.6 Gy With Concurrent 5-FU/Mitomycin C Is Superior to HART of 77.6 Gy Alone in Locally Advanced Head and Neck Cancer: Long-term Results of the ARO 95-06 Randomized Phase III Trial

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Budach, Volker, E-mail: volker.budach@charite.de; Stromberger, Carmen; Poettgen, Christoph

    2015-04-01

    Purpose: To report the long-term results of the ARO 95-06 randomized trial comparing hyperfractionated accelerated chemoradiation with mitomycin C/5-fluorouracil (C-HART) with hyperfractionated accelerated radiation therapy (HART) alone in locally advanced head and neck cancer. Patients and Methods: The primary endpoint was locoregional control (LRC). Three hundred eighty-four patients with stage III (6%) and IV (94%) oropharyngeal (59.4%), hypopharyngeal (32.3%), and oral cavity (8.3%) cancer were randomly assigned to 30 Gy/2 Gy daily followed by twice-daily 1.4 Gy to a total of 70.6 Gy concurrently with mitomycin C/5-FU (C-HART) or 16 Gy/2 Gy daily followed by twice-daily 1.4 Gy to a total dose of 77.6 Gy alone (HART). Statisticalmore » analyses were done with the log-rank test and univariate and multivariate Cox regression analyses. Results: The median follow-up time was 8.7 years (95% confidence interval [CI]: 7.8-9.7 years). At 10 years, the LRC rates were 38.0% (C-HART) versus 26.0% (HART, P=.002). The cancer-specific survival and overall survival rates were 39% and 10% (C-HART) versus 30.0% and 9% (HART, P=.042 and P=.049), respectively. According to multivariate Cox regression analysis, the combined treatment was associated with improved LRC (hazard ratio [HR]: 0.6 [95% CI: 0.5-0.8; P=.002]). The association between combined treatment arm and increased LRC appeared to be limited to oropharyngeal cancer (P=.003) as compared with hypopharyngeal or oral cavity cancer (P=.264). Conclusions: C-HART remains superior to HART in terms of LRC. However, this effect may be limited to oropharyngeal cancer patients.« less

  20. IMRT and RapidArc commissioning of a TrueBeam linear accelerator using TG-119 protocol cases.

    PubMed

    Wen, Ning; Zhao, Bo; Kim, Jinkoo; Chin-Snyder, Karen; Bellon, Maria; Glide-Hurst, Carri; Barton, Kenneth; Chen, Daiquan; Chetty, Indrin J

    2014-09-08

    The purpose of this study is to evaluate the overall accuracy of intensity-modulated radiation therapy (IMRT) and RapidArc delivery using both flattening filter (FF) and flattening filter-free (FFF) modalities based on test cases developed by AAPM Task Group 119. Institutional confidence limits (CLs) were established as the baseline for patient specific treatment plan quality assurance (QA). The effects of gantry range, gantry speed, leaf speed, dose rate, as well as the capability to capture intentional errors, were evaluated by measuring a series of Picket Fence (PF) tests using the electronic portal imaging device (EPID) and EBT3 films. Both IMRT and RapidArc plans were created in a Solid Water phantom (30 × 30 × 15 cm3) for the TG-119 test cases representative of normal clinical treatment sites for all five photon energies (6X, 10X, 15X, 6X-FFF, 10X-FFF) and the Exact IGRT couch was included in the dose calculation. One high-dose point in the PTV and one low-dose point in the avoidance structure were measured with an ion chamber in each case for each energy. Similarly, two GAFCHROMIC EBT3 films were placed in the coronal planes to measure planar dose distributions in both high- and low-dose regions. The confidence limit was set to have 95% of the measured data fall within the tolerance. The mean of the absolute dose deviation for variable dose rate and gantry speed during RapidArc delivery was within 0.5% for all energies. The corresponding results for leaf speed tests were all within 0.4%. The combinations of dynamic leaf gap (DLG) and MLC transmission factor were optimized based on the ion chamber measurement results of RapidArc delivery for each energy. The average 95% CLs for the high-dose point in the PTV were 0.030 ± 0.007 (range, 0.022-0.038) for the IMRT plans and 0.029 ± 0.011 (range, 0.016-0.043) for the RapidArc plans. For low-point dose in the avoidance structures, the CLs were 0.029 ± 0.006 (range, 0.024-0.039) for the IMRT plans and 0.027

  1. Dosimetric comparison of standard three-dimensional conformal radiotherapy followed by intensity-modulated radiotherapy boost schedule (sequential IMRT plan) with simultaneous integrated boost-IMRT (SIB IMRT) treatment plan in patients with localized carcinoma prostate.

    PubMed

    Bansal, A; Kapoor, R; Singh, S K; Kumar, N; Oinam, A S; Sharma, S C

    2012-07-01

    DOSIMETERIC AND RADIOBIOLOGICAL COMPARISON OF TWO RADIATION SCHEDULES IN LOCALIZED CARCINOMA PROSTATE: Standard Three-Dimensional Conformal Radiotherapy (3DCRT) followed by Intensity Modulated Radiotherapy (IMRT) boost (sequential-IMRT) with Simultaneous Integrated Boost IMRT (SIB-IMRT). Thirty patients were enrolled. In all, the target consisted of PTV P + SV (Prostate and seminal vesicles) and PTV LN (lymph nodes) where PTV refers to planning target volume and the critical structures included: bladder, rectum and small bowel. All patients were treated with sequential-IMRT plan, but for dosimetric comparison, SIB-IMRT plan was also created. The prescription dose to PTV P + SV was 74 Gy in both strategies but with different dose per fraction, however, the dose to PTV LN was 50 Gy delivered in 25 fractions over 5 weeks for sequential-IMRT and 54 Gy delivered in 27 fractions over 5.5 weeks for SIB-IMRT. The treatment plans were compared in terms of dose-volume histograms. Also, Tumor Control Probability (TCP) and Normal Tissue Complication Probability (NTCP) obtained with the two plans were compared. The volume of rectum receiving 70 Gy or more (V > 70 Gy) was reduced to 18.23% with SIB-IMRT from 22.81% with sequential-IMRT. SIB-IMRT reduced the mean doses to both bladder and rectum by 13% and 17%, respectively, as compared to sequential-IMRT. NTCP of 0.86 ± 0.75% and 0.01 ± 0.02% for the bladder, 5.87 ± 2.58% and 4.31 ± 2.61% for the rectum and 8.83 ± 7.08% and 8.25 ± 7.98% for the bowel was seen with sequential-IMRT and SIB-IMRT plans respectively. For equal PTV coverage, SIB-IMRT markedly reduced doses to critical structures, therefore should be considered as the strategy for dose escalation. SIB-IMRT achieves lesser NTCP than sequential-IMRT.

  2. Dosimetric comparison of standard three-dimensional conformal radiotherapy followed by intensity-modulated radiotherapy boost schedule (sequential IMRT plan) with simultaneous integrated boost–IMRT (SIB IMRT) treatment plan in patients with localized carcinoma prostate

    PubMed Central

    Bansal, A.; Kapoor, R.; Singh, S. K.; Kumar, N.; Oinam, A. S.; Sharma, S. C.

    2012-01-01

    Aims: Dosimeteric and radiobiological comparison of two radiation schedules in localized carcinoma prostate: Standard Three-Dimensional Conformal Radiotherapy (3DCRT) followed by Intensity Modulated Radiotherapy (IMRT) boost (sequential-IMRT) with Simultaneous Integrated Boost IMRT (SIB-IMRT). Material and Methods: Thirty patients were enrolled. In all, the target consisted of PTV P + SV (Prostate and seminal vesicles) and PTV LN (lymph nodes) where PTV refers to planning target volume and the critical structures included: bladder, rectum and small bowel. All patients were treated with sequential-IMRT plan, but for dosimetric comparison, SIB-IMRT plan was also created. The prescription dose to PTV P + SV was 74 Gy in both strategies but with different dose per fraction, however, the dose to PTV LN was 50 Gy delivered in 25 fractions over 5 weeks for sequential-IMRT and 54 Gy delivered in 27 fractions over 5.5 weeks for SIB-IMRT. The treatment plans were compared in terms of dose–volume histograms. Also, Tumor Control Probability (TCP) and Normal Tissue Complication Probability (NTCP) obtained with the two plans were compared. Results: The volume of rectum receiving 70 Gy or more (V > 70 Gy) was reduced to 18.23% with SIB-IMRT from 22.81% with sequential-IMRT. SIB-IMRT reduced the mean doses to both bladder and rectum by 13% and 17%, respectively, as compared to sequential-IMRT. NTCP of 0.86 ± 0.75% and 0.01 ± 0.02% for the bladder, 5.87 ± 2.58% and 4.31 ± 2.61% for the rectum and 8.83 ± 7.08% and 8.25 ± 7.98% for the bowel was seen with sequential-IMRT and SIB-IMRT plans respectively. Conclusions: For equal PTV coverage, SIB-IMRT markedly reduced doses to critical structures, therefore should be considered as the strategy for dose escalation. SIB-IMRT achieves lesser NTCP than sequential-IMRT. PMID:23204659

  3. Dynamic optical modulation of an electron beam on a photocathode RF gun: Toward intensity-modulated radiation therapy (IMRT)

    NASA Astrophysics Data System (ADS)

    Kondoh, Takafumi; Kashima, Hiroaki; Yang, Jinfeng; Yoshida, Yoichi; Tagawa, Seiichi

    2008-10-01

    In intensity-modulated radiation therapy (IMRT), the aim is to deliver reduced doses of radiation to normal tissue. As a step toward IMRT, we examined dynamic optical modulation of an electron beam produced by a photocathode RF gun. Images on photomasks were transferred onto a photocathode by relay imaging. The resulting beam was controlled by a remote mirror. The modulated electron beam maintained its shape on acceleration, had a fine spatial resolution, and could be moved dynamically by optical methods.

  4. A calibration method for patient specific IMRT QA using a single therapy verification film

    PubMed Central

    Shukla, Arvind Kumar; Oinam, Arun S.; Kumar, Sanjeev; Sandhu, I.S.; Sharma, S.C.

    2013-01-01

    Aim The aim of the present study is to develop and verify the single film calibration procedure used in intensity-modulated radiation therapy (IMRT) quality assurance. Background Radiographic films have been regularly used in routine commissioning of treatment modalities and verification of treatment planning system (TPS). The radiation dosimetery based on radiographic films has ability to give absolute two-dimension dose distribution and prefer for the IMRT quality assurance. However, the single therapy verification film gives a quick and significant reliable method for IMRT verification. Materials and methods A single extended dose rate (EDR 2) film was used to generate the sensitometric curve of film optical density and radiation dose. EDR 2 film was exposed with nine 6 cm × 6 cm fields of 6 MV photon beam obtained from a medical linear accelerator at 5-cm depth in solid water phantom. The nine regions of single film were exposed with radiation doses raging from 10 to 362 cGy. The actual dose measurements inside the field regions were performed using 0.6 cm3 ionization chamber. The exposed film was processed after irradiation using a VIDAR film scanner and the value of optical density was noted for each region. Ten IMRT plans of head and neck carcinoma were used for verification using a dynamic IMRT technique, and evaluated using the gamma index method with TPS calculated dose distribution. Results Sensitometric curve has been generated using a single film exposed at nine field region to check quantitative dose verifications of IMRT treatments. The radiation scattered factor was observed to decrease exponentially with the increase in the distance from the centre of each field region. The IMRT plans based on calibration curve were verified using the gamma index method and found to be within acceptable criteria. Conclusion The single film method proved to be superior to the traditional calibration method and produce fast daily film calibration for highly

  5. A feasibility study of [sup 252]Cf neutron brachytherapy, cisplatin + 5-FU chemo-adjuvant and accelerated hyperfractionated radiotherapy for advanced cervical cancer

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Murayama, Y.; Wierzbicki, J.; Bowen, M.G.

    The purpose was to evaluate the feasibility and toxicity of [sup 252]Cf neutron brachytherapy combined with hyperaccelerated chemoradiotherapy for Stage III and IV cervical cancers. Eleven patients with advanced Stage IIIB-IVA cervical cancers were treated with [sup 252]Cf neutron brachytherapy in an up-front schedule followed by cisplatin (CDDP; 50 mg/m[sup 2]) chemotherapy and hyperfractionated accelerated (1.2 Gy bid) radiotherapy given concurrently with intravenous infusion of 5-Fluorouracil (5-FU) (1000 mg/m[sup 2]/day [times] 4 days) in weeks 1 and 4 with conventional radiation (weeks 2, 3, 5, and 6). Total dose at a paracervical point A isodose surface was 80-85 Gy-eq bymore » external and intracavitary therapy and 60 Gy at the pelvic sidewalls. Patients tolerated the protocol well. There was 91% compliance with the chemotherapy and full compliance with the [sup 252]Cf brachytherapy and the external beam radiotherapy. There were no problems with acute chemo or radiation toxicity. One patient developed a rectovaginal fistula (Grade 3-4 RTOG criteria) but no other patients developed significant late cystitis, proctitis or enteritis. There was complete response (CR) observed in all cases. With mean follow-up to 26 months, local control has been achieved with 90% actuarial 3-year survival with no evidence of disease (NED). [sup 252]Cf neutrons can be combined with cisplatin and 5-FU infusion chemotherapy plus hyperaccelerated chemoradiotherapy without unusual side effects or toxicity and with a high local response and tumor control rate. Further study of [sup 252]Cf neutron-chemoradiotherapy for advanced and bulky cervical cancer are indicated. The authors found chemotherapy was more effective with the improved local tumor control. 18 refs., 2 tabs.« less

  6. Letter to the Editor on 'Single-Arc IMRT?'.

    PubMed

    Otto, Karl

    2009-04-21

    In the note 'Single Arc IMRT?' (Bortfeld and Webb 2009 Phys. Med. Biol. 54 N9-20), Bortfeld and Webb present a theoretical investigation of static gantry IMRT (S-IMRT), single-arc IMRT and tomotherapy. Based on their assumptions they conclude that single-arc IMRT is inherently limited in treating complex cases without compromising delivery efficiency. Here we present an expansion of their work based on the capabilities of the Varian RapidArc single-arc IMRT system. Using the same theoretical framework we derive clinically deliverable single-arc IMRT plans based on these specific capabilities. In particular, we consider the range of leaf motion, the ability to rapidly and continuously vary the dose rate and the choice of collimator angle used for delivery. In contrast to the results of Bortfeld and Webb, our results show that single-arc IMRT plans can be generated that closely match the theoretical optimum. The disparity in the results of each investigation emphasizes that the capabilities of the delivery system, along with the ability of the optimization algorithm to exploit those capabilities, are of particular importance in single-arc IMRT. We conclude that, given the capabilities available with the RapidArc system, single-arc IMRT can produce complex treatment plans that are delivered efficiently (in approximately 2 min).

  7. Peripheral doses from pediatric IMRT

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Klein, Eric E.; Maserang, Beth; Wood, Roy

    Peripheral dose (PD) data exist for conventional fields ({>=}10 cm) and intensity-modulated radiotherapy (IMRT) delivery to standard adult-sized phantoms. Pediatric peripheral dose reports are limited to conventional therapy and are model based. Our goal was to ascertain whether data acquired from full phantom studies and/or pediatric models, with IMRT treatment times, could predict Organ at Risk (OAR) dose for pediatric IMRT. As monitor units (MUs) are greater for IMRT, it is expected IMRT PD will be higher; potentially compounded by decreased patient size (absorption). Baseline slab phantom peripheral dose measurements were conducted for very small field sizes (from 2 tomore » 10 cm). Data were collected at distances ranging from 5 to 72 cm away from the field edges. Collimation was either with the collimating jaws or the multileaf collimator (MLC) oriented either perpendicular or along the peripheral dose measurement plane. For the clinical tests, five patients with intracranial or base of skull lesions were chosen. IMRT and conventional three-dimensional (3D) plans for the same patient/target/dose (180 cGy), were optimized without limitation to the number of fields or wedge use. Six MV, 120-leaf MLC Varian axial beams were used. A phantom mimicking a 3-year-old was configured per Center for Disease Control data. Micro (0.125 cc) and cylindrical (0.6 cc) ionization chambers were appropriated for the thyroid, breast, ovaries, and testes. The PD was recorded by electrometers set to the 10{sup -10} scale. Each system set was uniquely calibrated. For the slab phantom studies, close peripheral points were found to have a higher dose for low energy and larger field size and when MLC was not deployed. For points more distant from the field edge, the PD was higher for high-energy beams. MLC orientation was found to be inconsequential for the small fields tested. The thyroid dose was lower for IMRT delivery than that predicted for conventional (ratio of IMRT

  8. SU-F-T-384: Step and Shoot IMRT, VMAT and Autoplan VMAT Nasopharnyx Plan Robustness to Linear Accelerator Delivery Errors

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Pogson, EM; Liverpool and Macarthur Cancer Therapy Centres, Liverpool, NSW; Ingham Institute for Applied Medical Research, Sydney, NSW

    Purpose: To identify the robustness of different treatment techniques in respect to simulated linac errors on the dose distribution to the target volume and organs at risk for step and shoot IMRT (ssIMRT), VMAT and Autoplan generated VMAT nasopharynx plans. Methods: A nasopharynx patient dataset was retrospectively replanned with three different techniques: 7 beam ssIMRT, one arc manual generated VMAT and one arc automatically generated VMAT. Treatment simulated uncertainties: gantry, collimator, MLC field size and MLC shifts, were introduced into these plans at increments of 5,2,1,−1,−2 and −5 (degrees or mm) and recalculated in Pinnacle. The mean and maximum dosesmore » were calculated for the high dose PTV, parotids, brainstem, and spinal cord and then compared to the original baseline plan. Results: Simulated gantry angle errors have <1% effect on the PTV, ssIMRT is most sensitive. The small collimator errors (±1 and ±2 degrees) impacted the mean PTV dose by <2% for all techniques, however for the ±5 degree errors mean target varied by up to 7% for the Autoplan VMAT and 10% for the max dose to the spinal cord and brain stem, seen in all techniques. The simulated MLC shifts introduced the largest errors for the Autoplan VMAT, with the larger MLC modulation presumably being the cause. The most critical error observed, was the MLC field size error, where even small errors of 1 mm, caused significant changes to both the PTV and the OAR. The ssIMRT is the least sensitive and the Autoplan the most sensitive, with target errors of up to 20% over and under dosages observed. Conclusion: For a nasopharynx patient the plan robustness observed is highest for the ssIMRT plan and lowest for the Autoplan generated VMAT plan. This could be caused by the more complex MLC modulation seen for the VMAT plans. This project is supported by a grant from NSW Cancer Council.« less

  9. Restricted Field IMRT Dramatically Enhances IMRT Planning for Mesothelioma

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Allen, Aaron M.; Schofield, Deborah; Hacker, Fred

    2007-12-01

    Purpose: To improve the target coverage and normal tissue sparing of intensity-modulated radiotherapy (IMRT) for mesothelioma after extrapleural pneumonectomy. Methods and Materials: Thirteen plans from patients previously treated with IMRT for mesothelioma were replanned using a restricted field technique. This technique was novel in two ways. It limited the entrance beams to 200{sup o} around the target and three to four beams per case had their field apertures restricted down to the level of the heart or liver to further limit the contralateral lung dose. New constraints were added that included a mean lung dose of <9.5 Gy and volumemore » receiving {>=}5 Gy of <55%. Results: In all cases, the planning target volume coverage was excellent, with an average of 97% coverage of the planning target volume by the target dose. No change was seen in the target coverage with the new technique. The heart, kidneys, and esophagus were all kept under tolerance in all cases. The average mean lung dose, volume receiving {>=}20 Gy, and volume receiving {>=}5 Gy with the new technique was 6.6 Gy, 3.0%, and 50.8%, respectively, compared with 13.8 Gy, 15%, and 90% with the previous technique (p < 0.0001 for all three comparisons). The maximal value for any case in the cohort was 8.0 Gy, 7.3%, and 57.5% for the mean lung dose, volume receiving {>=}20 Gy, and volume receiving {>=}5 Gy, respectively. Conclusion: Restricted field IMRT provides an improved method to deliver IMRT to a complex target after extrapleural pneumonectomy. An upcoming Phase I trial will provide validation of these results.« less

  10. Dosimetric Comparison of Combined Intensity-Modulated Radiotherapy (IMRT) and Proton Therapy Versus IMRT Alone for Pelvic and Para-Aortic Radiotherapy in Gynecologic Malignancies

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Berman Milby, Abigail; Both, Stefan, E-mail: both@uphs.upenn.edu; Ingram, Mark

    2012-03-01

    Purpose: To perform a dosimetric comparison of intensity-modulated radiotherapy (IMRT), passive scattering proton therapy (PSPT), and intensity-modulated proton therapy (IMPT) to the para-aortic (PA) nodal region in women with locally advanced gynecologic malignancies. Methods and Materials: The CT treatment planning scans of 10 consecutive patients treated with IMRT to the pelvis and PA nodes were identified. The clinical target volume was defined by the primary tumor for patients with cervical cancer and by the vagina and paravaginal tissues for patients with endometrial cancer, in addition to the regional lymph nodes. The IMRT, PSPT, and IMPT plans were generated using themore » Eclipse Treatment Planning System and were analyzed for various dosimetric endpoints. Two groups of treatment plans including proton radiotherapy were created: IMRT to pelvic nodes with PSPT to PA nodes (PSPT/IMRT), and IMRT to pelvic nodes with IMPT to PA nodes (IMPT/IMRT). The IMRT and proton RT plans were optimized to deliver 50.4 Gy or Gy (relative biologic effectiveness [RBE)), respectively. Dose-volume histograms were analyzed for all of the organs at risk. The paired t test was used for all statistical comparison. Results: The small-bowel V{sub 20}, V{sub 30}, V{sub 35}, andV{sub 40} were reduced in PSPT/IMRT by 11%, 18%, 27%, and 43%, respectively (p < 0.01). Treatment with IMPT/IMRT demonstrated a 32% decrease in the small-bowel V{sub 20}. Treatment with PSPT/IMRT showed statistically significant reductions in the body V{sub 5-20}; IMPT/IMRT showed reductions in the body V{sub 5-15}. The dose received by half of both kidneys was reduced by PSPT/IMRT and by IMPT/IMRT. All plans maintained excellent coverage of the planning target volume. Conclusions: Compared with IMRT alone, PSPT/IMRT and IMPT/IMRT had a statistically significant decrease in dose to the small and large bowel and kidneys, while maintaining excellent planning target volume coverage. Further studies should be

  11. TH-EF-204-04: Experience of IMRT and Other Conformal Techniques in Russia

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Krylova, T.

    Joanna E. Cygler, Jan Seuntjens, J. Daniel Bourland, M. Saiful Huq, Josep Puxeu Vaque, Daniel Zucca Aparicio, Tatiana Krylova, Yuri Kirpichev, Eric Ford, Caridad Borras Stereotactic Radiation Therapy (SRT) utilizes small static and dynamic (IMRT) fields, to successfully treat malignant and benign diseases using techniques such as Stereotactic Radiosurgery (SRS) and Stereotactic Body Radiation Therapy (SBRT). SRT is characterized by sharp dose gradients for individual fields and their resultant dose distributions. For appropriate targets, small field radiotherapy offers improved treatment quality by allowing better sparing of organs at risk while delivering the prescribed target dose. Specialized small field treatment deliverymore » systems, such as robotic-controlled linear accelerators, gamma radiosurgery units, and dynamic arc linear accelerators may utilize rigid fixation, image guidance, and tumor tracking, to insure precise dose delivery to static or moving targets. However, in addition to great advantages, small field delivery techniques present special technical challenges for dose calibration due to unique geometries and small field sizes not covered by existing reference dosimetry protocols such as AAPM TG-51 or IAEA TRS 398. In recent years extensive research has been performed to understand small field dosimetry and measurement instrumentation. AAPM, IAEA and ICRU task groups are expected to provide soon recommendations on the dosimetry of small radiation fields. In this symposium we will: 1] discuss the physics, instrumentation, methodologies and challenges for small field radiation dose measurements; 2] review IAEA and ICRU recommendations on prescribing, recording and reporting of small field radiation therapy; 3] discuss selected clinical applications and technical aspects for specialized image-guided, small field, linear accelerator based treatment techniques such as IMRT and SBRT. Learning Objectives: To learn the physics of small fields in

  12. SU-E-T-278: Realization of Dose Verification Tool for IMRT Plan Based On DPM

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Cai, Jinfeng; Cao, Ruifen; Dai, Yumei

    Purpose: To build a Monte Carlo dose verification tool for IMRT Plan by implementing a irradiation source model into DPM code. Extend the ability of DPM to calculate any incident angles and irregular-inhomogeneous fields. Methods: With the virtual source and the energy spectrum which unfolded from the accelerator measurement data,combined with optimized intensity maps to calculate the dose distribution of the irradiation irregular-inhomogeneous field. The irradiation source model of accelerator was substituted by a grid-based surface source. The contour and the intensity distribution of the surface source were optimized by ARTS (Accurate/Advanced Radiotherapy System) optimization module based on the tumormore » configuration. The weight of the emitter was decided by the grid intensity. The direction of the emitter was decided by the combination of the virtual source and the emitter emitting position. The photon energy spectrum unfolded from the accelerator measurement data was adjusted by compensating the contaminated electron source. For verification, measured data and realistic clinical IMRT plan were compared with DPM dose calculation. Results: The regular field was verified by comparing with the measured data. It was illustrated that the differences were acceptable (<2% inside the field, 2–3mm in the penumbra). The dose calculation of irregular field by DPM simulation was also compared with that of FSPB (Finite Size Pencil Beam) and the passing rate of gamma analysis was 95.1% for peripheral lung cancer. The regular field and the irregular rotational field were all within the range of permitting error. The computing time of regular fields were less than 2h, and the test of peripheral lung cancer was 160min. Through parallel processing, the adapted DPM could complete the calculation of IMRT plan within half an hour. Conclusion: The adapted parallelized DPM code with irradiation source model is faster than classic Monte Carlo codes. Its computational accuracy

  13. Applications of IMAT in cervical esophageal cancer radiotherapy: a comparison with fixed-field IMRT in dosimetry and implementation.

    PubMed

    Yin, Yong; Chen, Jinhu; Xing, Ligang; Dong, Xiaoling; Liu, Tonghai; Lu, Jie; Yu, Jinming

    2011-01-13

    This study aimed to compare fixed-field, intensity-modulated radiotherapy (f-IMRT) with intensity-modulated arc therapy (IMAT) treatment plans in dosimetry and practical application for cervical esophageal carcinoma. For ten cervical esophageal carcinoma cases, f-IMRT plan (seven fixed-fields) and two IMAT plans, namely RA (coplanar 360° arcs) and RAx (coplanar 360° arcs without sectors from 80° to 110°, and 250° to 280°), were generated. DVHs were adopted for the statistics of above parameters, as well as conformal index (CI), homogeneity index (HI), dose-volumetric parameters of normal tissues, total accelerator output MUs and total treatment time. There were differences between RAx and f-IMRT, as well as RA in PTV parameters such as HI, V(95%) and V(110%), but not in CI. RAx reduced lung V₅ from (50.9% ± 9.8% in f-IMRT and (51.4% ± 10.8% in RA to (49.3% ± 10.4% in RAx (p < 0.05). However, lung V₃₀, V₄₀, V₅₀ and MLD increased in RAx. There was no difference in the mean heart dose in three plans. Total MU was reduced from 1174.8 ± 144.6 in f-IMRT to 803.8 ± 122.2 in RA and 736.2 ± 186.9 in RAx (p < 0.05). Compared with f-IMRT, IMAT reduced low dose volumes of lung and total MU on the basis of meeting clinical requirements.

  14. Reliable detection of fluence anomalies in EPID-based IMRT pretreatment quality assurance using pixel intensity deviations

    PubMed Central

    Gordon, J. J.; Gardner, J. K.; Wang, S.; Siebers, J. V.

    2012-01-01

    Purpose: This work uses repeat images of intensity modulated radiation therapy (IMRT) fields to quantify fluence anomalies (i.e., delivery errors) that can be reliably detected in electronic portal images used for IMRT pretreatment quality assurance. Methods: Repeat images of 11 clinical IMRT fields are acquired on a Varian Trilogy linear accelerator at energies of 6 MV and 18 MV. Acquired images are corrected for output variations and registered to minimize the impact of linear accelerator and electronic portal imaging device (EPID) positioning deviations. Detection studies are performed in which rectangular anomalies of various sizes are inserted into the images. The performance of detection strategies based on pixel intensity deviations (PIDs) and gamma indices is evaluated using receiver operating characteristic analysis. Results: Residual differences between registered images are due to interfraction positional deviations of jaws and multileaf collimator leaves, plus imager noise. Positional deviations produce large intensity differences that degrade anomaly detection. Gradient effects are suppressed in PIDs using gradient scaling. Background noise is suppressed using median filtering. In the majority of images, PID-based detection strategies can reliably detect fluence anomalies of ≥5% in ∼1 mm2 areas and ≥2% in ∼20 mm2 areas. Conclusions: The ability to detect small dose differences (≤2%) depends strongly on the level of background noise. This in turn depends on the accuracy of image registration, the quality of the reference image, and field properties. The longer term aim of this work is to develop accurate and reliable methods of detecting IMRT delivery errors and variations. The ability to resolve small anomalies will allow the accuracy of advanced treatment techniques, such as image guided, adaptive, and arc therapies, to be quantified. PMID:22894421

  15. Intensity-modulated radiotherapy (IMRT) for carcinoma of the maxillary sinus: A comparison of IMRT planning systems

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ahmed, Raef S.; Ove, Roger; Duan, Jun

    2006-10-01

    The treatment of maxillary sinus carcinoma with forward planning can be technically difficult when the neck also requires radiotherapy. This difficulty arises because of the need to spare the contralateral face while treating the bilateral neck. There is considerable potential for error in clinical setup and treatment delivery. We evaluated intensity-modulated radiotherapy (IMRT) as an improvement on forward planning, and compared several inverse planning IMRT platforms. A composite dose-volume histogram (DVH) was generated from a complex forward planned case. We compared the results with those generated by sliding window fixed field dynamic multileaf collimator (MLC) IMRT, using sets of coplanarmore » beams. All setups included an anterior posterior (AP) beam, and 3-, 5-, 7-, and 9-field configurations were evaluated. The dose prescription and objective function priorities were invariant. We also evaluated 2 commercial tomotherapy IMRT delivery platforms. DVH results from all of the IMRT approaches compared favorably with the forward plan. Results for the various inverse planning approaches varied considerably across platforms, despite an attempt to prescribe the therapy similarly. The improvement seen with the addition of beams in the fixed beam sliding window case was modest. IMRT is an effective means of delivering radiotherapy reliably in the complex setting of maxillary sinus carcinoma with neck irradiation. Differences in objective function definition and optimization algorithms can lead to unexpected differences in the final dose distribution, and our evaluation suggests that these factors are more significant than the beam arrangement or number of beams.« less

  16. Speed and convergence properties of gradient algorithms for optimization of IMRT.

    PubMed

    Zhang, Xiaodong; Liu, Helen; Wang, Xiaochun; Dong, Lei; Wu, Qiuwen; Mohan, Radhe

    2004-05-01

    Gradient algorithms are the most commonly employed search methods in the routine optimization of IMRT plans. It is well known that local minima can exist for dose-volume-based and biology-based objective functions. The purpose of this paper is to compare the relative speed of different gradient algorithms, to investigate the strategies for accelerating the optimization process, to assess the validity of these strategies, and to study the convergence properties of these algorithms for dose-volume and biological objective functions. With these aims in mind, we implemented Newton's, conjugate gradient (CG), and the steepest decent (SD) algorithms for dose-volume- and EUD-based objective functions. Our implementation of Newton's algorithm approximates the second derivative matrix (Hessian) by its diagonal. The standard SD algorithm and the CG algorithm with "line minimization" were also implemented. In addition, we investigated the use of a variation of the CG algorithm, called the "scaled conjugate gradient" (SCG) algorithm. To accelerate the optimization process, we investigated the validity of the use of a "hybrid optimization" strategy, in which approximations to calculated dose distributions are used during most of the iterations. Published studies have indicated that getting trapped in local minima is not a significant problem. To investigate this issue further, we first obtained, by trial and error, and starting with uniform intensity distributions, the parameters of the dose-volume- or EUD-based objective functions which produced IMRT plans that satisfied the clinical requirements. Using the resulting optimized intensity distributions as the initial guess, we investigated the possibility of getting trapped in a local minimum. For most of the results presented, we used a lung cancer case. To illustrate the generality of our methods, the results for a prostate case are also presented. For both dose-volume and EUD based objective functions, Newton's method far

  17. SU-F-T-271: Comparing IMRT QA Pass Rates Before and After MLC Calibration

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Mazza, A; Perrin, D; Fontenot, J

    Purpose: To compare IMRT QA pass rates before and after an in-house MLC leaf calibration procedure. Methods: The MLC leaves and backup jaws on four Elekta linear accelerators with MLCi2 heads were calibrated using the EPID-based RIT Hancock Test as the means for evaluation. The MLCs were considered to be successfully calibrated when they could pass the Hancock Test with criteria of 1 mm jaw position tolerance, and 1 mm leaf position tolerance. IMRT QA results were collected pre- and postcalibration and analyzed using gamma analysis with 3%/3mm DTA criteria. AAPM TG-119 test plans were also compared pre- and post-calibration,more » at both 2%/2mm DTA and 3%/3mm DTA. Results: A weighted average was performed on the results for all four linear accelerators. The pre-calibration IMRT QA pass rate was 98.3 ± 0.1%, compared with the post-calibration pass rate of 98.5 ± 0.1%. The TG-119 test plan results showed more of an improvement, particularly at the 2%/2mm criteria. The averaged results were 89.1% pre and 96.1% post for the C-shape plan, 94.8% pre and 97.1% post for the multi-target plan, 98.6% pre and 99.7% post for the prostate plan, 94.7% pre and 94.8% post for the head/neck plan. Conclusion: The patient QA results did not show statistically significant improvement at the 3%/3mm DTA criteria after the MLC calibration procedure. However, the TG-119 test cases did show significant improvement at the 2%/2mm level.« less

  18. A Phase I Study of Chemoradiotherapy With Use of Involved-Field Conformal Radiotherapy and Accelerated Hyperfractionation for Stage III Non-Small Cell Lung Cancer: WJTOG 3305

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Tada, Takuhito, E-mail: tada@msic.med.osaka-cu.ac.jp; Department of Radiology, Izumi Municipal Hospital, Izumi; Chiba, Yasutaka

    2012-05-01

    Purpose: A Phase I study to determine a recommended dose of thoracic radiotherapy using accelerated hyperfractionation for unresectable non-small-cell lung cancer was conducted. Methods and Materials: Patients with unresectable Stage III non-small-cell lung cancer were treated intravenously with carboplatin (area under the concentration curve 2) and paclitaxel (40 mg/m{sup 2}) on Days 1, 8, 15, and 22 with concurrent twice-daily thoracic radiotherapy (1.5 Gy per fraction) beginning on Day 1 followed by two cycles of consolidation chemotherapy using carboplatin (area under the concentration curve 5) and paclitaxel (200 mg/m{sup 2}). Total doses were 54 Gy in 36 fractions, 60 Gymore » in 40 fractions, 66 Gy in 44 fractions, and 72 Gy in 48 fractions at Levels 1 to 4. The dose-limiting toxicity, defined as Grade {>=}4 esophagitis and neutropenic fever and Grade {>=}3 other nonhematologic toxicities, was monitored for 90 days. Results: Of 26 patients enrolled, 22 patients were assessable for response and toxicity. When 4 patients entered Level 4, enrollment was closed to avoid severe late toxicities. Dose-limiting toxicities occurred in 3 patients. They were Grade 3 neuropathy at Level 1 and Level 3 and Grade 3 infection at Level 1. However, the maximum tolerated dose was not reached. The median survival time was 28.6 months for all patients. Conclusions: The maximum tolerated dose was not reached, although the dose of radiation was escalated to 72 Gy in 48 fractions. However, a dose of 66 Gy in 44 fractions was adopted for this study because late toxicity data were insufficient.« less

  19. Pre-trial quality assurance processes for an intensity-modulated radiation therapy (IMRT) trial: PARSPORT, a UK multicentre Phase III trial comparing conventional radiotherapy and parotid-sparing IMRT for locally advanced head and neck cancer.

    PubMed

    Clark, C H; Miles, E A; Urbano, M T Guerrero; Bhide, S A; Bidmead, A M; Harrington, K J; Nutting, C M

    2009-07-01

    The purpose of this study was to compare conventional radiotherapy with parotid gland-sparing intensity-modulated radiation therapy (IMRT) using the PARSPORT trial. The validity of such a trial depends on the radiotherapy planning and delivery meeting a defined standard across all centres. At the outset, many of the centres had little or no experience of delivering IMRT; therefore, quality assurance processes were devised to ensure consistency and standardisation of all processes for comparison within the trial. The pre-trial quality assurance (QA) programme and results are described. Each centre undertook exercises in target volume definition and treatment planning, completed a resource questionnaire and produced a process document. Additionally, the QA team visited each participating centre. Each exercise had to be accepted before patients could be recruited into the trial. 10 centres successfully completed the quality assurance exercises. A range of treatment planning systems, linear accelerators and delivery methods were used for the planning exercises, and all the plans created reached the standard required for participation in this multicentre trial. All 10 participating centres achieved implementation of a comprehensive and robust IMRT programme for treatment of head and neck cancer.

  20. IMRT for Image-Guided Single Vocal Cord Irradiation

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Osman, Sarah O.S., E-mail: s.osman@erasmusmc.nl; Astreinidou, Eleftheria; Boer, Hans C.J. de

    2012-02-01

    Purpose: We have been developing an image-guided single vocal cord irradiation technique to treat patients with stage T1a glottic carcinoma. In the present study, we compared the dose coverage to the affected vocal cord and the dose delivered to the organs at risk using conventional, intensity-modulated radiotherapy (IMRT) coplanar, and IMRT non-coplanar techniques. Methods and Materials: For 10 patients, conventional treatment plans using two laterally opposed wedged 6-MV photon beams were calculated in XiO (Elekta-CMS treatment planning system). An in-house IMRT/beam angle optimization algorithm was used to obtain the coplanar and non-coplanar optimized beam angles. Using these angles, the IMRTmore » plans were generated in Monaco (IMRT treatment planning system, Elekta-CMS) with the implemented Monte Carlo dose calculation algorithm. The organs at risk included the contralateral vocal cord, arytenoids, swallowing muscles, carotid arteries, and spinal cord. The prescription dose was 66 Gy in 33 fractions. Results: For the conventional plans and coplanar and non-coplanar IMRT plans, the population-averaged mean dose {+-} standard deviation to the planning target volume was 67 {+-} 1 Gy. The contralateral vocal cord dose was reduced from 66 {+-} 1 Gy in the conventional plans to 39 {+-} 8 Gy and 36 {+-} 6 Gy in the coplanar and non-coplanar IMRT plans, respectively. IMRT consistently reduced the doses to the other organs at risk. Conclusions: Single vocal cord irradiation with IMRT resulted in good target coverage and provided significant sparing of the critical structures. This has the potential to improve the quality-of-life outcomes after RT and maintain the same local control rates.« less

  1. SU-E-T-83: A Study On Evaluating the Directional Dependency of 2D Seven 29 Ion Chamber Array Clinically with Different IMRT Plans

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kumar, Syam; Aswathi, C.P.

    Purpose: To evaluate the directional dependency of 2D seven 29 ion chamber array clinically with different IMRT plans. Methods: 25 patients already treated with IMRT plans were selected for the study. Verification plans were created for each treatment plan in eclipse 10 treatment planning system using the AAA algorithm with the 2D array and the Octavius CT phantom. Verification plans were done 2 times for a single patient. First plan with real IMRT (plan-related approach) and second plan with zero degree gantry angle (field-related approach). Measurements were performed on a Varian Clinac-iX, linear accelerator equipped with a millennium 120 multileafmore » collimator. Fluence was measured for all the delivered plans and analyzed using the verisoft software. Comparison was done by selecting the fluence delivered in static gantry (zero degree gantry) versus IMRT with real gantry angles. Results: The gamma pass percentage is greater than 97 % for all IMRT delivered with zero gantry angle and between 95%–98% for real gantry angles. Dose difference between the TPS calculated and measured for IMRT delivered with zero gantry angle was found to be between (0.03 to 0.06Gy) and with real gantry angles between (0.02 to 0.05Gy). There is a significant difference between the gamma analysis between the zero degree and true angle with a significance of 0.002. Standard deviation of gamma pass percentage between the IMRT plans with zero gantry angle was 0.68 and for IMRT with true gantry angle was found to be 0.74. Conclusion: The gamma analysis for IMRT with zero degree gantry angles shows higher pass percentage than IMRT delivered with true gantry angles. Verification plans delivered with true gantry angles lower the verification accuracy when 2D array is used for measurement.« less

  2. Statistical process control analysis for patient-specific IMRT and VMAT QA.

    PubMed

    Sanghangthum, Taweap; Suriyapee, Sivalee; Srisatit, Somyot; Pawlicki, Todd

    2013-05-01

    This work applied statistical process control to establish the control limits of the % gamma pass of patient-specific intensity modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT) quality assurance (QA), and to evaluate the efficiency of the QA process by using the process capability index (Cpml). A total of 278 IMRT QA plans in nasopharyngeal carcinoma were measured with MapCHECK, while 159 VMAT QA plans were undertaken with ArcCHECK. Six megavolts with nine fields were used for the IMRT plan and 2.5 arcs were used to generate the VMAT plans. The gamma (3%/3 mm) criteria were used to evaluate the QA plans. The % gamma passes were plotted on a control chart. The first 50 data points were employed to calculate the control limits. The Cpml was calculated to evaluate the capability of the IMRT/VMAT QA process. The results showed higher systematic errors in IMRT QA than VMAT QA due to the more complicated setup used in IMRT QA. The variation of random errors was also larger in IMRT QA than VMAT QA because the VMAT plan has more continuity of dose distribution. The average % gamma pass was 93.7% ± 3.7% for IMRT and 96.7% ± 2.2% for VMAT. The Cpml value of IMRT QA was 1.60 and VMAT QA was 1.99, which implied that the VMAT QA process was more accurate than the IMRT QA process. Our lower control limit for % gamma pass of IMRT is 85.0%, while the limit for VMAT is 90%. Both the IMRT and VMAT QA processes are good quality because Cpml values are higher than 1.0.

  3. Comparison of the extent of hippocampal sparing according to the tilt of a patient's head during WBRT using linear accelerator-based IMRT and VMAT.

    PubMed

    Moon, Sun Young; Yoon, Myonggeun; Chung, Mijoo; Chung, Weon Kuu; Kim, Dong Wook

    2016-05-01

    In this paper, we report the results of our investigation into whole brain radiotherapy (WBRT) using linear accelerator-based intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT) in lung cancer patients with a high risk of metastasis to the brain. Specifically, we assessed the absorbed dose and the rate of adverse effects for several organs at risk (OAR), including the hippocampus, according to the tilt of a patient's head. We arbitrarily selected five cases where measurements were made with the patients' heads tilted forward and five cases without such tilt. We set the entire brain as the planning target volume (PTV), and the hippocampi, the lenses, the eyes, and the cochleae as the main OAR, and formulated new plans for IMRT (coplanar, non-coplanar) and VMAT (coplanar, non-coplanar). Using the dose-volume histogram (DVH), we calculated and compared the effective uniform dose (EUD), normal tissue complication probability (NTCP) of the OAR and the mean and the maximum doses of hippocampus. As a result, if the patient tilted the head forward when receiving the Linac-based treatment, for the same treatment effect in the PTV, we confirmed that a lower dose entered the OAR, such as the hippocampus, eye, lens, and cochlea. Moreover, the damage to the hippocampus was expected to be the least when receiving coplanar VMAT with the head tilted forward. Accordingly, if patients tilt their heads forward when undergoing Linac-based WBRT, we anticipate that a smaller dose would be transmitted to the OAR, resulting in better quality of life following treatment. Copyright © 2016 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  4. SU-E-T-784: Using MLC Log Files for Daily IMRT Delivery Verification

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Stathakis, S; Defoor, D; Linden, P

    2015-06-15

    Purpose: To verify daily intensity modulated radiation therapy (IMRT) treatments using multi-leaf collimator (MLC) log files. Methods: The MLC log files from a NovalisTX Varian linear accelerator were used in this study. The MLC files were recorded daily for all patients undergoing IMRT or volumetric modulated arc therapy (VMAT). The first record of each patient was used as reference and all records for subsequent days were compared against the reference. An in house MATLAB software code was used for the comparisons. Each MLC log file was converted to a fluence map (FM) and a gamma index (γ) analysis was usedmore » for the evaluation of each daily delivery for every patient. The tolerance for the gamma index was set to 2% dose difference and 2mm distance to agreement while points with signal of 10% or lower of the maximum value were excluded from the comparisons. Results: The γ between each of the reference FMs and the consecutive daily fraction FMs had an average value of 99.1% (ranged from 98.2 to 100.0%). The FM images were reconstructed at various resolutions in order to study the effect of the resolution on the γ and at the same time reduce the time for processing the images. We found that the comparison of images with the highest resolution (768×1024) yielded on average a lower γ (99.1%) than the ones with low resolution (192×256) (γ 99.5%). Conclusion: We developed an in-house software that allows us to monitor the quality of daily IMRT and VMAT treatment deliveries using information from the MLC log files of the linear accelerator. The information can be analyzed and evaluated as early as after the completion of each daily treatment. Such tool can be valuable to assess the effect of MLC positioning on plan quality, especially in the context of adaptive radiotherapy.« less

  5. Final Results of a Randomized Phase 2 Trial Investigating the Addition of Cetuximab to Induction Chemotherapy and Accelerated or Hyperfractionated Chemoradiation for Locoregionally Advanced Head and Neck Cancer

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Seiwert, Tanguy Y., E-mail: tseiwert@medicine.bsd.uchicago.edu; Melotek, James M.; Blair, Elizabeth A.

    Purpose: The role of cetuximab in the treatment of locoregionally advanced head and neck squamous cell cancer (LA-HNSCC) remains poorly defined. In this phase 2 randomized study, we investigated the addition of cetuximab to both induction chemotherapy (IC) and hyperfractionated or accelerated chemoradiation. Methods and Materials: Patients with LA-HNSCC were randomized to receive 2 cycles of weekly IC (cetuximab, paclitaxel, carboplatin) and either Cetux-FHX (concurrent cetuximab, 5-fluorouracil, hydroxyurea, and 1.5 Gy twice-daily radiation therapy every other week to 75 Gy) or Cetux-PX (cetuximab, cisplatin, and accelerated radiation therapy with delayed concomitant boost to 72 Gy in 42 fractions). The primary endpoint was progression-freemore » survival (PFS), with superiority compared with historical control achieved if either arm had 2-year PFS ≥70%. Results: 110 patients were randomly assigned to either Cetux-FHX (n=57) or Cetux-PX (n=53). The overall response rate to IC was 91%. Severe toxicity on IC was limited to rash (23% grade ≥3) and myelosuppression (38% grade ≥3 neutropenia). The 2-year rates of PFS for both Cetux-FHX (82.5%) and Cetux-PX (84.9%) were significantly higher than for historical control (P<.001). The 2-year overall survival (OS) was 91.2% for Cetux-FHX and 94.3% for Cetux-PX. With a median follow-up time of 72 months, there were no significant differences in PFS (P=.35) or OS (P=.15) between the treatment arms. The late outcomes for the entire cohort included 5-year PFS, OS, locoregional failure, and distant metastasis rates of 74.1%, 80.3%, 15.7%, and 7.4%, respectively. The 5-year PFS and OS were 84.4% and 91.3%, respectively, among human papillomavirus (HPV)-positive patients and 65.9% and 72.5%, respectively, among HPV-negative patients. Conclusions: The addition of cetuximab to IC and chemoradiation was tolerable and produced long-term control of LA-HNSCC, particularly among poor-prognosis HPV-negative patients. Further

  6. Automated IMRT planning with regional optimization using planning scripts

    PubMed Central

    Wong, Eugene; Bzdusek, Karl; Lock, Michael; Chen, Jeff Z.

    2013-01-01

    Intensity‐modulated radiation therapy (IMRT) has become a standard technique in radiation therapy for treating different types of cancers. Various class solutions have been developed for simple cases (e.g., localized prostate, whole breast) to generate IMRT plans efficiently. However, for more complex cases (e.g., head and neck, pelvic nodes), it can be time‐consuming for a planner to generate optimized IMRT plans. To generate optimal plans in these more complex cases which generally have multiple target volumes and organs at risk, it is often required to have additional IMRT optimization structures such as dose limiting ring structures, adjust beam geometry, select inverse planning objectives and associated weights, and additional IMRT objectives to reduce cold and hot spots in the dose distribution. These parameters are generally manually adjusted with a repeated trial and error approach during the optimization process. To improve IMRT planning efficiency in these more complex cases, an iterative method that incorporates some of these adjustment processes automatically in a planning script is designed, implemented, and validated. In particular, regional optimization has been implemented in an iterative way to reduce various hot or cold spots during the optimization process that begins with defining and automatic segmentation of hot and cold spots, introducing new objectives and their relative weights into inverse planning, and turn this into an iterative process with termination criteria. The method has been applied to three clinical sites: prostate with pelvic nodes, head and neck, and anal canal cancers, and has shown to reduce IMRT planning time significantly for clinical applications with improved plan quality. The IMRT planning scripts have been used for more than 500 clinical cases. PACS numbers: 87.55.D, 87.55.de PMID:23318393

  7. A Varian DynaLog file-based procedure for patient dose-volume histogram-based IMRT QA.

    PubMed

    Calvo-Ortega, Juan F; Teke, Tony; Moragues, Sandra; Pozo, Miquel; Casals-Farran, Joan

    2014-03-06

    In the present study, we describe a method based on the analysis of the dynamic MLC log files (DynaLog) generated by the controller of a Varian linear accelerator in order to perform patient-specific IMRT QA. The DynaLog files of a Varian Millennium MLC, recorded during an IMRT treatment, can be processed using a MATLAB-based code in order to generate the actual fluence for each beam and so recalculate the actual patient dose distribution using the Eclipse treatment planning system. The accuracy of the DynaLog-based dose reconstruction procedure was assessed by introducing ten intended errors to perturb the fluence of the beams of a reference plan such that ten subsequent erroneous plans were generated. In-phantom measurements with an ionization chamber (ion chamber) and planar dose measurements using an EPID system were performed to investigate the correlation between the measured dose changes and the expected ones detected by the reconstructed plans for the ten intended erroneous cases. Moreover, the method was applied to 20 cases of clinical plans for different locations (prostate, lung, breast, and head and neck). A dose-volume histogram (DVH) metric was used to evaluate the impact of the delivery errors in terms of dose to the patient. The ionometric measurements revealed a significant positive correlation (R² = 0.9993) between the variations of the dose induced in the erroneous plans with respect to the reference plan and the corresponding changes indicated by the DynaLog-based reconstructed plans. The EPID measurements showed that the accuracy of the DynaLog-based method to reconstruct the beam fluence was comparable with the dosimetric resolution of the portal dosimetry used in this work (3%/3 mm). The DynaLog-based reconstruction method described in this study is a suitable tool to perform a patient-specific IMRT QA. This method allows us to perform patient-specific IMRT QA by evaluating the result based on the DVH metric of the planning CT image (patient

  8. General strategy for the protection of organs at risk in IMRT therapy of a moving body

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Abolfath, Ramin M.; Papiez, Lech

    2009-07-15

    We investigated protection strategies of organs at risk (OARs) in intensity modulated radiation therapy (IMRT). These strategies apply to delivery of IMRT to moving body anatomies that show relative displacement of OAR in close proximity to a tumor target. We formulated an efficient genetic algorithm which makes it possible to search for global minima in a complex landscape of multiple irradiation strategies delivering a given, predetermined intensity map to a target. The optimal strategy was investigated with respect to minimizing the dose delivered to the OAR. The optimization procedure developed relies on variability of all parameters available for control ofmore » radiation delivery in modern linear accelerators, including adaptation of leaf trajectories and simultaneous modification of beam dose rate during irradiation. We showed that the optimization algorithms lead to a significant reduction in the dose delivered to OAR in cases where organs at risk move relative to a treatment target.« less

  9. MO-D-213-05: Sensitivity of Routine IMRT QA Metrics to Couch and Collimator Rotations

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Alaei, P

    Purpose: To assess the sensitivity of gamma index and other IMRT QA metrics to couch and collimator rotations. Methods: Two brain IMRT plans with couch and/or collimator rotations in one or more of the fields were evaluated using the IBA MatriXX ion chamber array and its associated software (OmniPro-I’mRT). The plans were subjected to routine QA by 1) Creating a composite planar dose in the treatment planning system (TPS) with the couch/collimator rotations and 2) Creating the planar dose after “zeroing” the rotations. Plan deliveries to MatriXX were performed with all rotations set to zero on a Varian 21ex linearmore » accelerator. This in effect created TPS-created planar doses with an induced rotation error. Point dose measurements for the delivered plans were also performed in a solid water phantom. Results: The IMRT QA of the plans with couch and collimator rotations showed clear discrepancies in the planar dose and 2D dose profile overlays. The gamma analysis, however, did pass with the criteria of 3%/3mm (for 95% of the points), albeit with a lower percentage pass rate, when one or two of the fields had a rotation. Similar results were obtained with tighter criteria of 2%/2mm. Other QA metrics such as percentage difference or distance-to-agreement (DTA) histograms produced similar results. The point dose measurements did not obviously indicate the error due to location of dose measurement (on the central axis) and the size of the ion chamber used (0.6 cc). Conclusion: Relying on Gamma analysis, percentage difference, or DTA to determine the passing of an IMRT QA may miss critical errors in the plan delivery due to couch/collimator rotations. A combination of analyses for composite QA plans, or per-beam analysis, would detect these errors.« less

  10. Genital marginal failures after intensity-modulated radiation therapy (IMRT) in squamous cell anal cancer: no higher risk with IMRT when compared to 3DCRT.

    PubMed

    Dell'Acqua, V; Kobiela, J; Kraja, F; Leonardi, M C; Surgo, A; Zerella, M A; Arculeo, S; Fodor, C; Ricotti, R; Zampino, M G; Ravenda, S; Spinoglio, G; Biffi, R; Bazani, A; Luraschi, R; Vigorito, S; Spychalski, P; Orecchia, R; Glynne-Jones, R; Jereczek-Fossa, B A

    2018-03-28

    Intensity-modulated radiotherapy (IMRT) is considered the preferred option in squamous cell canal cancer (SCAC), delivering high doses to tumor volumes while minimizing dose to surrounding normal tissues. IMRT has steep dose gradients, but the technique is more demanding as deep understanding of target structures is required. To evaluate genital marginal failure in a cohort of patients with non-metastatic SCAC treated either with IMRT or 3DCRT and concurrent chemotherapy, 117 patients with SCAC were evaluated: 64 and 53 patients were treated with IMRT and 3DCRT techniques, respectively. All patients underwent clinical and radiological examination during their follow-up. Tumor response was evaluated with response evaluation criteria in solid tumors v1.1 guideline on regular basis. All patients' data were analyzed, and patients with marginal failure were identified. Concomitant chemotherapy was administered in 97 and 77.4% of patients in the IMRT and 3DCRT groups, respectively. In the IMRT group, the median follow-up was 25 months (range 6-78). Progressive disease was registered in 15.6% of patients; infield recurrence, distant recurrence and both infield recurrence and distant recurrence were identified in 5, 4 and 1 patient, respectively. Two out of 64 patients (3.1%) had marginal failures, localized at vagina/recto-vaginal septum and left perineal region. In the 3DCRT group, the median follow-up was 71.3 months (range 6-194 months). Two out of 53 patients (3.8%) had marginal failures, localized at recto-vaginal septum and perigenital structures. The rate of marginal failures was comparable in IMRT and 3DCRT groups (χ 2 test p = 0.85). In this series, the use of IMRT for the treatment of SCAC did not increase the rate of marginal failures offering improved dose conformity to the target. Dose constraints should be applied with caution-particularly in females with involvement of the vagina or the vaginal septum.

  11. Evaluation of Larynx-Sparing Techniques With IMRT When Treating the Head and Neck

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Webster, Gareth J.; Rowbottom, Carl G.; Ho, Kean F.

    2008-10-01

    Purpose: Concern exists that widespread implementation of whole-field intensity-modulated radiotherapy (IMRT) for the treatment of head-and-neck cancer has resulted in increased levels of dysphagia relative to those seen with conventional planning. Other investigators have suggested an alternative junctioned-IMRT (J-IMRT) method, which matches an IMRT plan to a centrally blocked neck field to restrict the laryngeal dose and reduce dysphagia. The effect on target coverage and sparing of organs at risk, including laryngeal sparing, in the optimization was evaluated and compared with that achieved using a J-IMRT technique. Methods and Materials: A total of 13 oropharyngeal cancer whole-field IMRT plans weremore » planned with and without including laryngeal sparing in the optimization. A comparison of the target coverage and sparing of organs at risk was made using the resulting dose-volume histograms and dose distribution. The nine plans with disease located superior to the level of the larynx were replanned using a series of J-IMRT techniques to compare the two laryngeal-sparing techniques. Results: An average mean larynx dose of 29.1 Gy was achieved if disease did not extend to the level of the larynx, with 38.8 Gy for disease extending inferiorly and close to the larynx (reduced from 46.2 and 47.7 Gy, respectively, without laryngeal sparing). Additional laryngeal sparing could be achieved with J-IMRT (mean dose 24.4 Gy), although often at the expense of significantly reduced coverage of the target volume and with no improvement to other areas of the IMRT plan. Conclusion: The benefits of J-IMRT can be achieved with whole-field IMRT if laryngeal sparing is incorporated into the class solution. Inclusion of laryngeal sparing had no effect on other parameters in the plan.« less

  12. Randomized Trial of Hyperfractionation Versus Conventional Fractionation in T2 Squamous Cell Carcinoma of the Vocal Cord (RTOG 9512)

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Trotti, Andy, E-mail: andy.trotti@moffitt.org; Zhang, Qiang; Bentzen, Søren M.

    2014-08-01

    Purpose: To compare hyperfractionation versus standard fractionation for T2N0 vocal cord carcinoma in a randomized controlled trial. Methods and Materials: Patients with T2 vocal cord cancer were stratified by substage (T2a vs T2b) and randomly assigned to receive either hyperfractionation (HFX) to 79.2 Gy in 66 fractions of 1.2 Gy given twice a day, or standard fractionation (SFX) to 70 Gy in 35 fractions given once a day. The trial was designed to detect a 55% reduction in the local failure hazard rate with 80% statistical power. Results: Between April 1996 and July 2003, a total of 250 patients were enrolled. Of 239more » patients analyzable for outcomes, 94% were male, 83% had a Karnofsky performance status of 90-100, and 62% had T2a tumor. Median follow-up for all surviving patients was 7.9 years (range, 0.6-13.1 years). The 5-year local control (LC) rate was 8 points higher but not statistically significant (P=.14 for HFX [78%] vs SFX [70%]), corresponding to a 30% hazard rate reduction. The 5-year disease-free survival (DFS) was 49% versus 40% (P=.13) and overall survival (OS) was 72% versus 63% (P=.29). HFX was associated with higher rates of acute skin, mucosal, and laryngeal toxicity. Grade 3-4 late effects were similar with a 5-year cumulative incidence of 8.5% (3.4%-13.6%) after SFX and 8.5% (3.4%-13.5%) after HFX. Conclusions: The 5-year local control was modestly higher with HFX compared to SFX for T2 glottic carcinoma, but the difference was not statistically significant. These results are consistent with prior studies of hyperfractionation showing a benefit in local control. Substaging by T2a versus T2b carries prognostic value for DFS and OS. For cost and convenience reasons other altered fractionation schedules have been adopted in routine practice.« less

  13. Intensity Modulated Radiotherapy (IMRT) in head and neck cancers - an overview.

    PubMed

    Nutting, C M

    2012-07-01

    Radiotherapy (RT) is effective in head and neck cancers. Following RT, dryness and dysphagia are the 2 major sequelae which alter the quality of life (QOL) significantly in these patients. There is randomized evidence that Intensity Modulated Radiotherapy (IMRT) effectively spares the parotid glands. IMRT has been attempted in all head and neck subsites with encouraging results (discussed below). Role of IMRT in swallowing structure (constrictor muscles) sparing is less clear.Further improvement in results may be possible by using functional imaging at the time of RT planning and by image guidance/verification at the time of treatment delivery. The following text discusses these issues in detail. Head and neck cancer, IMRT.

  14. Cardiac-Sparing Whole Lung IMRT in Children With Lung Metastasis

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kalapurakal, John A., E-mail: j-kalapurakal@northwestern.edu; Zhang, Yunkai; Kepka, Alan

    Purpose: To demonstrate the dosimetric advantages of cardiac-sparing (CS) intensity modulated radiation therapy (IMRT) in children undergoing whole lung irradiation (WLI). Methods and Materials: Chest CT scans of 22 children who underwent simulation with 3-dimensional (n=10) or 4-dimensional (n=12) techniques were used for this study. Treatment planning was performed using standard anteroposterior-posteroanterior (S-RT) technique and CS-IMRT. Left and right flank fields were added to WLI fields to determine whether CS-IMRT offered any added protection to normal tissues at the junction between these fields. The radiation dose to the lung PTV, cardiac structures, liver, and thyroid were analyzed and compared. Results:more » CS-IMRT had 4 significant advantages over S-RT: (1) superior cardiac protection (2) superior 4-dimensional lung planning target volume coverage, (3) superior dose uniformity in the lungs with fewer hot spots, and (4) significantly lower dose to the heart when flank RT is administered after WLI. Conclusions: The use of CS-IMRT and 4-dimensional treatment planning has the potential to improve tumor control rates and reduce cardiac toxicity in children receiving WLI.« less

  15. A comprehensive comparison of IMRT and VMAT plan quality for prostate cancer treatment

    PubMed Central

    QUAN, ENZHUO M.; LI, XIAOQIANG; LI, YUPENG; WANG, XIAOCHUN; KUDCHADKER, RAJAT J.; JOHNSON, JENNIFER L.; KUBAN, DEBORAH A.; LEE, ANDREW K.; ZHANG, XIAODONG

    2013-01-01

    Purpose We performed a comprehensive comparative study of the plan quality between volumetric modulated arc therapy (VMAT) and intensity-modulated radiation therapy (IMRT) for the treatment of prostate cancer. Methods and Materials Eleven patients with prostate cancer treated at our institution were randomly selected for this study. For each patient, a VMAT plan and a series of IMRT plans using an increasing number of beams (8, 12, 16, 20, and 24 beams) were examined. All plans were generated using our in-house-developed automatic inverse planning (AIP) algorithm. An existing 8-beam clinical IMRT plan, which was used to treat the patient, was used as the reference plan. For each patient, all AIP-generated plans were optimized to achieve the same level of planning target volume (PTV) coverage as the reference plan. Plan quality was evaluated by measuring mean dose to and dose-volume statistics of the organs-at-risk, especially the rectum, from each type of plan. Results For the same PTV coverage, the AIP-generated VMAT plans had significantly better plan quality in terms of rectum sparing than the 8-beam clinical and AIP-generated IMRT plans (p < 0.0001). However, the differences between the IMRT and VMAT plans in all the dosimetric indices decreased as the number of beams used in IMRT increased. IMRT plan quality was similar or superior to that of VMAT when the number of beams in IMRT was increased to a certain number, which ranged from 12 to 24 for the set of patients studied. The superior VMAT plan quality resulted in approximately 30% more monitor units than the 8-beam IMRT plans, but the delivery time was still less than 3 minutes. Conclusions Considering the superior plan quality as well as the delivery efficiency of VMAT compared with that of IMRT, VMAT may be the preferred modality for treating prostate cancer. PMID:22704703

  16. Poster - Thur Eve - 29: Detecting changes in IMRT QA using statistical process control.

    PubMed

    Drever, L; Salomons, G

    2012-07-01

    Statistical process control (SPC) methods were used to analyze 239 measurement based individual IMRT QA events. The selected IMRT QA events were all head and neck (H&N) cases with 70Gy in 35 fractions, and all prostate cases with 76Gy in 38 fractions planned between March 2009 and 2012. The results were used to determine if the tolerance limits currently being used for IMRT QA were able to indicate if the process was under control. The SPC calculations were repeated for IMRT QA of the same type of cases that were planned after the treatment planning system was upgraded from Eclipse version 8.1.18 to version 10.0.39. The initial tolerance limits were found to be acceptable for two of the three metrics tested prior to the upgrade. After the upgrade to the treatment planning system the SPC analysis found that the a priori limits were no longer capable of indicating control for 2 of the 3 metrics analyzed. The changes in the IMRT QA results were clearly identified using SPC, indicating that it is a useful tool for finding changes in the IMRT QA process. Routine application of SPC to IMRT QA results would help to distinguish unintentional trends and changes from the random variation in the IMRT QA results for individual plans. © 2012 American Association of Physicists in Medicine.

  17. A dose homogeneity and conformity evaluation between ViewRay and pinnacle-based linear accelerator IMRT treatment plans

    PubMed Central

    Saenz, Daniel L.; Paliwal, Bhudatt R.; Bayouth, John E.

    2014-01-01

    ViewRay, a novel technology providing soft-tissue imaging during radiotherapy is investigated for treatment planning capabilities assessing treatment plan dose homogeneity and conformity compared with linear accelerator plans. ViewRay offers both adaptive radiotherapy and image guidance. The combination of cobalt-60 (Co-60) with 0.35 Tesla magnetic resonance imaging (MRI) allows for magnetic resonance (MR)-guided intensity-modulated radiation therapy (IMRT) delivery with multiple beams. This study investigated head and neck, lung, and prostate treatment plans to understand what is possible on ViewRay to narrow focus toward sites with optimal dosimetry. The goal is not to provide a rigorous assessment of planning capabilities, but rather a first order demonstration of ViewRay planning abilities. Images, structure sets, points, and dose from treatment plans created in Pinnacle for patients in our clinic were imported into ViewRay. The same objectives were used to assess plan quality and all critical structures were treated as similarly as possible. Homogeneity index (HI), conformity index (CI), and volume receiving <20% of prescription dose (DRx) were calculated to assess the plans. The 95% confidence intervals were recorded for all measurements and presented with the associated bars in graphs. The homogeneity index (D5/D95) had a 1-5% inhomogeneity increase for head and neck, 3-8% for lung, and 4-16% for prostate. CI revealed a modest conformity increase for lung. The volume receiving 20% of the prescription dose increased 2-8% for head and neck and up to 4% for lung and prostate. Overall, for head and neck Co-60 ViewRay treatments planned with its Monte Carlo treatment planning software were comparable with 6 MV plans computed with convolution superposition algorithm on Pinnacle treatment planning system. PMID:24872603

  18. A dose homogeneity and conformity evaluation between ViewRay and pinnacle-based linear accelerator IMRT treatment plans.

    PubMed

    Saenz, Daniel L; Paliwal, Bhudatt R; Bayouth, John E

    2014-04-01

    ViewRay, a novel technology providing soft-tissue imaging during radiotherapy is investigated for treatment planning capabilities assessing treatment plan dose homogeneity and conformity compared with linear accelerator plans. ViewRay offers both adaptive radiotherapy and image guidance. The combination of cobalt-60 (Co-60) with 0.35 Tesla magnetic resonance imaging (MRI) allows for magnetic resonance (MR)-guided intensity-modulated radiation therapy (IMRT) delivery with multiple beams. This study investigated head and neck, lung, and prostate treatment plans to understand what is possible on ViewRay to narrow focus toward sites with optimal dosimetry. The goal is not to provide a rigorous assessment of planning capabilities, but rather a first order demonstration of ViewRay planning abilities. Images, structure sets, points, and dose from treatment plans created in Pinnacle for patients in our clinic were imported into ViewRay. The same objectives were used to assess plan quality and all critical structures were treated as similarly as possible. Homogeneity index (HI), conformity index (CI), and volume receiving <20% of prescription dose (DRx) were calculated to assess the plans. The 95% confidence intervals were recorded for all measurements and presented with the associated bars in graphs. The homogeneity index (D5/D95) had a 1-5% inhomogeneity increase for head and neck, 3-8% for lung, and 4-16% for prostate. CI revealed a modest conformity increase for lung. The volume receiving 20% of the prescription dose increased 2-8% for head and neck and up to 4% for lung and prostate. Overall, for head and neck Co-60 ViewRay treatments planned with its Monte Carlo treatment planning software were comparable with 6 MV plans computed with convolution superposition algorithm on Pinnacle treatment planning system.

  19. Interplay effect on a 6-MV flattening-filter-free linear accelerator with high dose rate and fast multi-leaf collimator motion treating breast and lung phantoms.

    PubMed

    Netherton, Tucker; Li, Yuting; Nitsch, Paige; Shaitelman, Simona; Balter, Peter; Gao, Song; Klopp, Ann; Muruganandham, Manickam; Court, Laurence

    2018-06-01

    Using a new linear accelerator with high dose rate (800 MU/min), fast MLC motions (5.0 cm/s), fast gantry rotation (15 s/rotation), and 1 cm wide MLCs, we aimed to quantify the effects of complexity, arc number, and fractionation on interplay for breast and lung treatments under target motion. To study lung interplay, eight VMAT plans (1-6 arcs) and four-nine-field sliding-window IMRT plans varying in complexity were created. For the breast plans, four-four-field sliding-window IMRT plans were created. Using the Halcyon 1.0 linear accelerator, each plan was delivered five times each under sinusoidal breathing motion to a phantom with 20 implanted MOSFET detectors; MOSFET dose (cGy), delivery time, and MU/cGy values were recorded. Maximum and mean dose deviations were calculated from MOSFET data. The number of MOSFETs with at least 19 of 20 detectors agreeing with their expected dose within 5% per fraction was calculated across 10 6 iterations to model dose deviation as function of fraction number for all plan variants. To put interplay plans into clinical context, additional IMRT and VMAT plans were created and delivered for the sites of head and neck, prostate, whole brain, breast, pelvis, and lung. Average modulation and interplay effect were compared to those from conventional linear accelerators, as reported from previous studies. The mean beam modulation for plans created for the Halcyon 1.0 linear accelerator was 2.9 MU/cGy (two- to four-field IMRT breast plans), 6.2 MU/cGy (at least five-field IMRT), and 3.6 MU/cGy (four-arc VMAT). To achieve treatment plan objectives, Halcyon 1.0 VMAT plans require more arcs and modulation than VMAT on conventional linear accelerators. Maximum and mean dose deviations increased with increasing plan complexity under tumor motion for breast and lung treatments. Concerning VMAT plans under motion, maximum, and mean dose deviations were higher for one arc than for two arcs regardless of plan complexity. For plan variants

  20. Comparison of VMAT and IMRT strategies for cervical cancer patients using automated planning.

    PubMed

    Sharfo, Abdul Wahab M; Voet, Peter W J; Breedveld, Sebastiaan; Mens, Jan Willem M; Hoogeman, Mischa S; Heijmen, Ben J M

    2015-03-01

    In a published study on cervical cancer, 5-beam IMRT was inferior to single arc VMAT. Here we compare 9, 12, and 20 beam IMRT with single and dual arc VMAT. For each of 10 patients, automated plan generation with the in-house Erasmus-iCycle optimizer was used to assist an expert planner in generating the five plans with the clinical TPS. For each patient, all plans were clinically acceptable with a high and similar PTV coverage. OAR sparing increased when going from 9 to 12 to 20 IMRT beams, and from single to dual arc VMAT. For all patients, 12 and 20 beam IMRT were superior to single and dual arc VMAT, with substantial variations in gain among the study patients. As expected, delivery of VMAT plans was significantly faster than delivery of IMRT plans. Often reported increased plan quality for VMAT compared to IMRT has not been observed for cervical cancer. Twenty and 12 beam IMRT plans had a higher quality than single and dual arc VMAT. For individual patients, the optimal delivery technique depends on a complex trade-off between plan quality and treatment time that may change with introduction of faster delivery systems. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  1. MO-G-BRD-01: Point/Counterpoint Debate: Arc Based Techniques Will Make Conventional IMRT Obsolete

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Shepard, D; Popple, R; Balter, P

    2014-06-15

    A variety of intensity modulated radiation therapy (IMRT) delivery techniques have been developed that have provided clinicians with the ability to deliver highly conformal dose distributions. The delivery techniques include compensators, step-and-shoot IMRT, sliding window IMRT, volumetric modulated arc therapy (VMAT), and tomotherapy. A key development in the field of IMRT was the introduction of new planning algorithms and delivery control systems in 2007 that made it possible to coordinate the gantry rotation speed, dose rate, and multileaf collimator leaf positions during the delivery of arc therapy. With these developments, VMAT became a routine clinical tool. The use of VMATmore » has continued to grow in recent years and some would argue that this will soon make conventional IMRT obsolete, and this is the premise of this debate. To introduce the debate, David Shepard, Ph.D. will provide an overview of IMRT delivery techniques including historical context and how they are being used today. The debate will follow with Richard Popple, Ph.D. arguing FOR the Proposition and Peter Balter, Ph.D. arguing AGAINST it. Learning Objectives: Understand the different delivery techniques for IMRT. Understand the potential benefits of conventional IMRT. Understand the potential benefits of arc-based IMRT delivery.« less

  2. Generation of a novel phase-space-based cylindrical dose kernel for IMRT optimization.

    PubMed

    Zhong, Hualiang; Chetty, Indrin J

    2012-05-01

    Improving dose calculation accuracy is crucial in intensity-modulated radiation therapy (IMRT). We have developed a method for generating a phase-space-based dose kernel for IMRT planning of lung cancer patients. Particle transport in the linear accelerator treatment head of a 21EX, 6 MV photon beam (Varian Medical Systems, Palo Alto, CA) was simulated using the EGSnrc/BEAMnrc code system. The phase space information was recorded under the secondary jaws. Each particle in the phase space file was associated with a beamlet whose index was calculated and saved in the particle's LATCH variable. The DOSXYZnrc code was modified to accumulate the energy deposited by each particle based on its beamlet index. Furthermore, the central axis of each beamlet was calculated from the orientation of all the particles in this beamlet. A cylinder was then defined around the central axis so that only the energy deposited within the cylinder was counted. A look-up table was established for each cylinder during the tallying process. The efficiency and accuracy of the cylindrical beamlet energy deposition approach was evaluated using a treatment plan developed on a simulated lung phantom. Profile and percentage depth doses computed in a water phantom for an open, square field size were within 1.5% of measurements. Dose optimized with the cylindrical dose kernel was found to be within 0.6% of that computed with the nontruncated 3D kernel. The cylindrical truncation reduced optimization time by approximately 80%. A method for generating a phase-space-based dose kernel, using a truncated cylinder for scoring dose, in beamlet-based optimization of lung treatment planning was developed and found to be in good agreement with the standard, nontruncated scoring approach. Compared to previous techniques, our method significantly reduces computational time and memory requirements, which may be useful for Monte-Carlo-based 4D IMRT or IMAT treatment planning.

  3. Image processing for IMRT QA dosimetry.

    PubMed

    Zaini, Mehran R; Forest, Gary J; Loshek, David D

    2005-01-01

    We have automated the determination of the placement location of the dosimetry ion chamber within intensity-modulated radiotherapy (IMRT) fields, as part of streamlining the entire IMRT quality assurance process. This paper describes the mathematical image-processing techniques to arrive at the appropriate measurement locations within the planar dose maps of the IMRT fields. A specific spot within the found region is identified based on its flatness, radiation magnitude, location, area, and the avoidance of the interleaf spaces. The techniques used include applying a Laplacian, dilation, erosion, region identification, and measurement point selection based on three parameters: the size of the erosion operator, the gradient, and the importance of the area of a region versus its magnitude. These three parameters are adjustable by the user. However, the first one requires tweaking in extremely rare occasions, the gradient requires rare adjustments, and the last parameter needs occasional fine-tuning. This algorithm has been tested in over 50 cases. In about 5% of cases, the algorithm does not find a measurement point due to the extremely steep and narrow regions within the fluence maps. In such cases, manual selection of a point is allowed by our code, which is also difficult to ascertain, since the fluence map does not yield itself to an appropriate measurement point selection.

  4. Comments on shielding for dual energy accelerators.

    PubMed

    Rossi, M C; Lincoln, H M; Quarin, D J; Zwicker, R D

    2008-06-01

    Determination of shielding requirements for medical linear accelerators has been greatly facilitated by the publication of the National Council on Radiation Protection and Measurements (NCRP) latest guidelines on this subject in NCRP Report No. 151. In the present report the authors review their own recent experience with patient treatments on conventional dual energy linear accelerators to examine the various input parameters needed to follow the NCRP guidelines. Some discussion is included of workloads, occupancy, use factors, and field size, with the effects of intensity modulated radiotherapy (IMRT) treatments included. Studies of collimator settings showed average values of 13.1 x 16.2 cm2 for 6 MV and 14.1 x 16.8 cm2 for 18 MV conventional ports, and corresponding average unblocked areas of 228 and 254 cm2, respectively. With an average of 77% of the field area unblocked, this gives a mean irradiated area of 196 cm2 for the 18 MV beam, which dominates shielding considerations for most dual energy machines. Assuming conservatively small room dimensions, a gantry bin angle of 18 degrees was found to represent a reasonable unit for tabulation of use factors. For conventional 18 MV treatments it was found that the usual treatment angles of 0, 90, 180, and 270 degrees were still favored, and use factors of 0.25 represent reasonable estimates for these beams. As expected, the IMRT fields (all at 6 MV) showed a high degree of gantry angle randomization, with no bin having a use factor in excess of 0.10. It is concluded that unless a significant number of patients are treated with high energy IMRT, the traditional use factors of 0.25 are appropriate for the dominant high energy beam.

  5. Phase I/II Trial of Hyperfractionated Concomitant Boost Proton Radiotherapy for Supratentorial Glioblastoma Multiforme

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Mizumoto, Masashi; Tsuboi, Koji, E-mail: tsuboi@pmrc.tsukuba.ac.j; Department of Neurosurgery, Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba, Ibaraki

    2010-05-01

    Purpose: To evaluate the safety and efficacy of postoperative hyperfractionated concomitant boost proton radiotherapy with nimustine hydrochloride for supratentorial glioblastoma multiforme (GBM). Methods and Materials: Twenty patients with histologically confirmed supratentorial GBM met the following criteria: (1) a Karnofsky performance status of >=60; (2) the diameter of the enhanced area before radiotherapy was <=40 cm; and (3) the enhanced area did not extend to the brain stem, hypothalamus, or thalamus. Magnetic resonance imaging (MRI) T{sub 2}-weighted high area (clinical tumor volume 3 [CTV3]) was treated by x-ray radiotherapy in the morning (50.4 Gy in 28 fractions). More than 6 hoursmore » later, 250 MeV proton beams were delivered to the enhanced area plus a 10-mm margin (CTV2) in the first half of the protocol (23.1 GyE in 14 fractions) and to the enhanced volume (CTV1) in the latter half (23.1 GyE in 14 fraction). The total dose to the CTV1 was 96.6 GyE. Nimustine hydrochloride (80 mg/m2) was administered during the first and fourth weeks. Results: Acute toxicity was mainly hematologic and was controllable. Late radiation necrosis and leukoencephalopathy were each seen in one patient. The overall survival rates after 1 and 2 years were 71.1% and 45.3%, respectively. The median survival period was 21.6 months. The 1- and 2-year progression-free survival rates were 45.0% and 15.5%, respectively. The median MRI change-free survival was 11.2 months. Conclusions: Hyperfractionated concomitant boost proton radiotherapy (96.6 GyE in 56 fractions) for GBM was tolerable and beneficial if the target size was well considered. Further studies are warranted to pursue the possibility of controlling border region recurrences.« less

  6. Optimization of Craniospinal Irradiation for Pediatric Medulloblastoma Using VMAT and IMRT.

    PubMed

    Al-Wassia, Rolina K; Ghassal, Noor M; Naga, Adly; Awad, Nesreen A; Bahadur, Yasir A; Constantinescu, Camelia

    2015-10-01

    Intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT) provide highly conformal target radiation doses, but also expose large volumes of healthy tissue to low-dose radiation. With improving survival, more children with medulloblastoma (MB) are at risk of late adverse effects of radiotherapy, including secondary cancers. We evaluated the characteristics of IMRT and VMAT craniospinal irradiation treatment plans in children with standard-risk MB to compare radiation dose delivery to target organs and organs at risk (OAR). Each of 10 children with standard-risk MB underwent both IMRT and VMAT treatment planning. Dose calculations used inverse planning optimization with a craniospinal dose of 23.4 Gy followed by a posterior fossa boost to 55.8 Gy. Clinical and planning target volumes were demarcated on axial computed tomography images. Dose distributions to target organs and OAR for each planning technique were measured and compared with published dose-volume toxicity data for pediatric patients. All patients completed treatment planning for both techniques. Analyses and comparisons of dose distributions and dose-volume histograms for the planned target volumes, and dose delivery to the OAR for each technique demonstrated the following: (1) VMAT had a modest, but significantly better, planning target volume-dose coverage and homogeneity compared with IMRT; (2) there were different OAR dose-sparing profiles for IMRT versus VMAT; and (3) neither IMRT nor VMAT demonstrated dose reductions to the published pediatric dose limits for the eyes, the lens, the cochlea, the pituitary, and the brain. The use of both IMRT and VMAT provides good target tissue coverage and sparing of the adjacent tissue for MB. Both techniques resulted in OAR dose delivery within published pediatric dose guidelines, except those mentioned above. Pediatric patients with standard-risk MB remain at risk for late endocrinologic, sensory (auditory and visual), and brain

  7. BOOK REVIEW: Image-Guided IMRT

    NASA Astrophysics Data System (ADS)

    Mayles, P.

    2006-12-01

    This book provides comprehensive coverage of the subject of intensity modulated radiotherapy and the associated imaging. Most of the names associated with advanced radiotherapy can be found among the 80 authors and the book is therefore an authoritative reference text. The early chapters deal with the basic principles and include an interesting comparison between views of quality assurance for IMRT from Europe and North America. It is refreshing to see that the advice given has moved on from the concept of individual patient based quality control to more generic testing of the delivery system. However, the point is made that the whole process including the data transfer needs to be quality assured and the need for thorough commissioning of the process is emphasised. The `tricks' needed to achieve a dose based IMRT plan are well covered by the group at Ghent and there is an interesting summary of biological aspects of treatment planning for IMRT by Andrzej Niemierko. The middle section of the book deals with advanced imaging aspects of both treatment planning and delivery. The contributions of PET and MR imaging are well covered and there is a rather rambling section on molecular imaging. Image guidance in radiotherapy treatment is addressed including the concept of adaptive radiotherapy. The treatment aspects could perhaps have merited some more coverage, but there is a very thorough discussion of 4D techniques. The final section of the book considers each site of the body in turn. This will be found useful by those wishing to embark on IMRT in a new area, although some of the sections are more comprehensive than others. The book contains a wealth of interesting and thought provoking articles giving details as well as broad principles, and would be a useful addition to every departmental library. The editors have done a good job of ensuring that the different chapters are complementary, and of encouraging a systematic approach to the descriptions of IMRT in

  8. In vivo prostate IMRT dosimetry with MOSFET detectors using brass buildup caps

    PubMed Central

    Varadhan, Raj; Miller, John; Garrity, Brenden; Weber, Michael

    2006-01-01

    The feasibility of using dual bias metal oxide semiconductor field effect transistor (MOSFET) detectors with the new hemispherical brass buildup cap for in vivo dose measurements in prostate intensity‐modulated radiotherapy (IMRT) treatments was investigated and achieved. In this work, MOSFET detectors with brass buildup caps placed on the patient's skin surface on the central axis of the individual IMRT beams are used to determine the maximum entrance dose (Dmax) from the prostate IMRT fields. A general formalism with various correction factors taken into account to predict Dmax entrance dose for the IMRT fields with MOSFETs was developed and compared against predicted dose from the treatment‐planning system (TPS). We achieved an overall accuracy of better than ±5% on all measured fields for both 6‐MV and 10‐MV beams when compared to predicted doses from the Philips Pinnacle 3 and CMS XiO TPSs, respectively. We also estimate the total uncertainty in estimation of MOSFET dose in the high‐sensitivity mode for IMRT therapy to be 4.6%. PACS numbers: 87.53Xd, 87.56Fc PMID:17533354

  9. Volumetric-modulated arc therapy vs c-IMRT in esophageal cancer: A treatment planning comparison

    PubMed Central

    Yin, Li; Wu, Hao; Gong, Jian; Geng, Jian-Hao; Jiang, Fan; Shi, An-Hui; Yu, Rong; Li, Yong-Heng; Han, Shu-Kui; Xu, Bo; Zhu, Guang-Ying

    2012-01-01

    AIM: To compare the volumetric-modulated arc therapy (VMAT) plans with conventional sliding window intensity-modulated radiotherapy (c-IMRT) plans in esophageal cancer (EC). METHODS: Twenty patients with EC were selected, including 5 cases located in the cervical, the upper, the middle and the lower thorax, respectively. Five plans were generated with the eclipse planning system: three using c-IMRT with 5 fields (5F), 7 fields (7F) and 9 fields (9F), and two using VMAT with a single arc (1A) and double arcs (2A). The treatment plans were designed to deliver a dose of 60 Gy to the planning target volume (PTV) with the same constrains in a 2.0 Gy daily fraction, 5 d a week. Plans were normalized to 95% of the PTV that received 100% of the prescribed dose. We examined the dose-volume histogram parameters of PTV and the organs at risk (OAR) such as lungs, spinal cord and heart. Monitor units (MU) and normal tissue complication probability (NTCP) of OAR were also reported. RESULTS: Both c-IMRT and VMAT plans resulted in abundant dose coverage of PTV for EC of different locations. The dose conformity to PTV was improved as the number of field in c-IMRT or rotating arc in VMAT was increased. The doses to PTV and OAR in VMAT plans were not statistically different in comparison with c-IMRT plans, with the following exceptions: in cervical and upper thoracic EC, the conformity index (CI) was higher in VMAT (1A 0.78 and 2A 0.8) than in c-IMRT (5F 0.62, 7F 0.66 and 9F 0.73) and homogeneity was slightly better in c-IMRT (7F 1.09 and 9F 1.07) than in VMAT (1A 1.1 and 2A 1.09). Lung V30 was lower in VMAT (1A 12.52 and 2A 12.29) than in c-IMRT (7F 14.35 and 9F 14.81). The humeral head doses were significantly increased in VMAT as against c-IMRT. In the middle and lower thoracic EC, CI in VMAT (1A 0.76 and 2A 0.74) was higher than in c-IMRT (5F 0.63 Gy and 7F 0.67 Gy), and homogeneity was almost similar between VMAT and c-IMRT. V20 (2A 21.49 Gy vs 7F 24.59 Gy and 9F 24.16 Gy) and V

  10. Volumetric-modulated arc therapy vs. c-IMRT in esophageal cancer: a treatment planning comparison.

    PubMed

    Yin, Li; Wu, Hao; Gong, Jian; Geng, Jian-Hao; Jiang, Fan; Shi, An-Hui; Yu, Rong; Li, Yong-Heng; Han, Shu-Kui; Xu, Bo; Zhu, Guang-Ying

    2012-10-07

    To compare the volumetric-modulated arc therapy (VMAT) plans with conventional sliding window intensity-modulated radiotherapy (c-IMRT) plans in esophageal cancer (EC). Twenty patients with EC were selected, including 5 cases located in the cervical, the upper, the middle and the lower thorax, respectively. Five plans were generated with the eclipse planning system: three using c-IMRT with 5 fields (5F), 7 fields (7F) and 9 fields (9F), and two using VMAT with a single arc (1A) and double arcs (2A). The treatment plans were designed to deliver a dose of 60 Gy to the planning target volume (PTV) with the same constrains in a 2.0 Gy daily fraction, 5 d a week. Plans were normalized to 95% of the PTV that received 100% of the prescribed dose. We examined the dose-volume histogram parameters of PTV and the organs at risk (OAR) such as lungs, spinal cord and heart. Monitor units (MU) and normal tissue complication probability (NTCP) of OAR were also reported. Both c-IMRT and VMAT plans resulted in abundant dose coverage of PTV for EC of different locations. The dose conformity to PTV was improved as the number of field in c-IMRT or rotating arc in VMAT was increased. The doses to PTV and OAR in VMAT plans were not statistically different in comparison with c-IMRT plans, with the following exceptions: in cervical and upper thoracic EC, the conformity index (CI) was higher in VMAT (1A 0.78 and 2A 0.8) than in c-IMRT (5F 0.62, 7F 0.66 and 9F 0.73) and homogeneity was slightly better in c-IMRT (7F 1.09 and 9F 1.07) than in VMAT (1A 1.1 and 2A 1.09). Lung V30 was lower in VMAT (1A 12.52 and 2A 12.29) than in c-IMRT (7F 14.35 and 9F 14.81). The humeral head doses were significantly increased in VMAT as against c-IMRT. In the middle and lower thoracic EC, CI in VMAT (1A 0.76 and 2A 0.74) was higher than in c-IMRT (5F 0.63 Gy and 7F 0.67 Gy), and homogeneity was almost similar between VMAT and c-IMRT. V20 (2A 21.49 Gy vs. 7F 24.59 Gy and 9F 24.16 Gy) and V30 (2A 9.73 Gy vs. 5F

  11. Variable beam dose rate and DMLC IMRT to moving body anatomy

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Papiez, Lech; Abolfath, Ramin M.

    2008-11-15

    Derivation of formulas relating leaf speeds and beam dose rates for delivering planned intensity profiles to static and moving targets in dynamic multileaf collimator (DMLC) intensity modulated radiation therapy (IMRT) is presented. The analysis of equations determining algorithms for DMLC IMRT delivery under a variable beam dose rate reveals a multitude of possible delivery strategies for a given intensity map and for any given target motion patterns. From among all equivalent delivery strategies for DMLC IMRT treatments specific subclasses of strategies can be selected to provide deliveries that are particularly suitable for clinical applications providing existing delivery devices are used.more » Special attention is devoted to the subclass of beam dose rate variable DMLC delivery strategies to moving body anatomy that generalize existing techniques of such deliveries in Varian DMLC irradiation methodology to static body anatomy. Few examples of deliveries from this subclass of DMLC IMRT irradiations are investigated to illustrate the principle and show practical benefits of proposed techniques.« less

  12. SU-F-T-274: Modified Dose Calibration Methods for IMRT QA

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Luo, W; Westlund, S

    2016-06-15

    Purpose: To investigate IMRT QA uncertainties caused by dose calibration and modify widely used dose calibration procedures to improve IMRT QA accuracy and passing rate. Methods: IMRT QA dose measurement is calibrated using a calibration factor (CF) that is the ratio between measured value and expected value corresponding to the reference fields delivered on a phantom. Two IMRT QA phantoms were used for this study: a 30×30×30 cm3 solid water cube phantom (Cube), and the PTW Octavius phantom. CF was obtained by delivering 100 MUs to the phantoms with different reference fields ranging from 3×3 cm2 to 20×20 cm{sup 2}.more » For Cube, CFs were obtained using the following beam arrangements: 2-AP Field - chamber at dmax, 2-AP Field - chamber at isocenter, 4-beam box - chamber at isocenter, and 8 equally spaced fields and chamber at isocenter. The same plans were delivered on Octavius and CFs were derived for the dose at the isocenter using the above beam arrangements. The Octavius plans were evaluated with PTW-VeriSoft (Gamma criteria of 3%/3mm). Results: Four head and neck IMRT plans were included in this study. For point dose measurement with Cube, the CFs with 4-Field gave the best agreement between measurement and calculation within 4% for large field plans. All the measurement results agreed within 2% for a small field plan. Compared with calibration field sizes, 5×5 to 15×15 were more accurate than other field sizes. For Octavius, 4-Field calibration increased passing rate by up to 10% compared to AP calibration. Passing rate also increased by up to 4% with the increase of field size from 3×3 to 20×20. Conclusion: IMRT QA results are correlated with calibration methods used. The dose calibration using 4-beam box with field sizes from 5×5 to 20×20 can improve IMRT QA accuracy and passing rate.« less

  13. Volumetric modulated arc therapy vs. IMRT for the treatment of distal esophageal cancer.

    PubMed

    Van Benthuysen, Liam; Hales, Lee; Podgorsak, Matthew B

    2011-01-01

    Several studies have demonstrated that volumetric modulated arc therapy (VMAT) has the ability to reduce monitor units and treatment time when compared with intensity-modulated radiation therapy (IMRT). This study aims to demonstrate that VMAT is able to provide adequate organs at risk (OAR) sparing and planning target volume (PTV) coverage for adenocarcinoma of the distal esophagus while reducing monitor units and treatment time. Fourteen patients having been treated previously for esophageal cancer were planned using both VMAT and IMRT techniques. Dosimetric quality was evaluated based on doses to several OARs, as well as coverage of the PTV. Treatment times were assessed by recording the number of monitor units required for dose delivery. Body V(5) was also recorded to evaluate the increased volume of healthy tissue irradiated to low doses. Dosimetric differences in OAR sparing between VMAT and IMRT were comparable. PTV coverage was similar for the 2 techniques but it was found that IMRT was capable of delivering a slightly more homogenous dose distribution. Of the 14 patients, 12 were treated with a single arc and 2 were treated with a double arc. Single-arc plans reduced monitor units by 42% when compared with the IMRT plans. Double-arc plans reduced monitor units by 67% when compared with IMRT. The V(5) for the body was found to be 18% greater for VMAT than for IMRT. VMAT has the capability to decrease treatment times over IMRT while still providing similar OAR sparing and PTV coverage. Although there will be a smaller risk of patient movement during VMAT treatments, this advantage comes at the cost of delivering small doses to a greater volume of the patient. Copyright © 2011 American Association of Medical Dosimetrists. Published by Elsevier Inc. All rights reserved.

  14. Comparison of four commercial devices for RapidArc and sliding window IMRT QA

    PubMed Central

    Chandraraj, Varatharaj; Manickam, Ravikumar; Esquivel, Carlos; Supe, Sanjay S.; Papanikolaou, Nikos

    2011-01-01

    For intensity‐modulated radiation therapy, evaluation of the measured dose against the treatment planning calculated dose is essential in the context of patient‐specific quality assurance. The complexity of volumetric arc radiotherapy delivery attributed to its dynamic and synchronization nature require new methods and potentially new tools for the quality assurance of such techniques. In the present study, we evaluated and compared the dosimetric performance of EDR2 film and three other commercially available quality assurance devices: IBA I'MatriXX array, PTW Seven29 array and the Delta 4 array. The evaluation of these dosimetric systems was performed for RapidArc and IMRT deliveries using a Varian NovalisTX linear accelerator. The plans were generated using the Varian Eclipse treatment planning system. Our results showed that all four QA techniques yield equivalent results. All patient QAs passed our institutional clinical criteria of gamma index based on a 3% dose difference and 3 mm distance to agreement. In addition, the Bland‐Altman analysis was performed which showed that all the calculated gamma values of all three QA devices were within 5% from those of the film. The results showed that the four QA systems used in this patient‐specific IMRT QA analysis are equivalent. We concluded that the dosimetric systems under investigation can be used interchangeably for routine patient specific QA. PACS numbers: 87.55.Qr, 87.56.Fc

  15. Superior sulcus non-small cell lung carcinoma: A comparison of IMRT and 3D-RT dosimetry.

    PubMed

    Truntzer, Pierre; Antoni, Delphine; Santelmo, Nicola; Schumacher, Catherine; Falcoz, Pierre-Emmanuel; Quoix, Elisabeth; Massard, Gilbert; Noël, Georges

    2016-01-01

    A dosimetric study comparing intensity modulated radiotherapy (IMRT) by TomoTherapy to conformational 3D radiotherapy (3D-RT) in patients with superior sulcus non-small cell lung cancer (NSCLC). IMRT became the main technique in modern radiotherapy. However it was not currently used for lung cancers. Because of the need to increase the dose to control lung cancers but because of the critical organs surrounding the tumors, the gains obtainable with IMRT is not still demonstrated. A dosimetric comparison of the planned target and organs at risk parameters between IMRT and 3D-RT in eight patients who received preoperative or curative intent irradiation. In the patients who received at least 66 Gy, the mean V95% was significantly better with IMRT than 3D-RT (p = 0.043). IMRT delivered a lower D2% compared to 3D-RT (p = 0.043). The IH was significantly better with IMRT (p = 0.043). The lung V 5 Gy and V 13 Gy were significantly higher in IMRT than 3D-RT (p = 0.043), while the maximal dose (D max) to the spinal cord was significantly lower in IMRT (p = 0.043). The brachial plexus D max was significantly lower in IMRT than 3D-RT (p = 0.048). For patients treated with 46 Gy, no significant differences were found. Our study showed that IMRT is relevant for SS-NSCLC. In patients treated with a curative dose, it led to a reduction of the exposure of critical organs, allowing a better dose distribution in the tumor. For the patients treated with a preoperative schedule, our results provide a basis for future controlled trials to improve the histological complete response by increasing the radiation dose.

  16. Dosimetric comparison of normal structures associated with accelerated partial breast irradiation and whole breast irradiation delivered by intensity modulated radiotherapy for early breast cancer after breast conserving surgery.

    PubMed

    Wu, S; He, Z; Guo, J; Li, F; Lin, Q; Guan, X

    2014-01-01

    To assess the heart and lung dosimetry results associated with accelerated partial breast irradiation intensity-modulated radiotherapy (APBI-IMRT) and whole breast field-in-field intensity-modulated radiotherapy (WBI-FIF-IMRT). A total of 29 patients with early-stage breast cancer after lumpectomy were included in this study. APBI-IMRT and WBI-FIF-IMRT plans were generated for each patient. The dosimetric parameters of ipsilateral lung and heart in both plans were then compared with and without radiobiological correction. With and without radiobiological correction, the volume of ipsilateral lung showed a substantially lower radiation exposure in APBI-IMRT with moderate to high doses (P < 0.05) but non-significant increases in volume of ipsilateral lung in 2.5 Gy than WBI-FIF-IMRT (P > 0.905).There was no significant difference in volume of ipsilateral lung receiving 1, 2.5, and 5 Gy between APBI-IMRT and WBI (P > 0.05) in patients with medial tumor location, although APBI-IMRT exposed more lung to 2.5 and 5 Gy. APBI-IMRT significantly decreases the volume of heart receiving low to high doses in left-sided breast cancer (P < 0.05). APBI-IMRT can significantly spare the volume of heart and ipsilateral lung receiving moderate and high dose. Non-significant increases in volume of the ipsilateral lung exposed to low doses of radiation were observed for APBI-IMRT in comparison to WBI-FIF-IMRT, particularly in patients with medial tumor location. With the increasing interest in APBI-IMRT, our data may help clinicians individualize patient treatment decisions.

  17. Intensity-modulated radiotherapy (IMRT) in pediatric low-grade glioma.

    PubMed

    Paulino, Arnold C; Mazloom, Ali; Terashima, Keita; Su, Jack; Adesina, Adekunle M; Okcu, M Faith; Teh, Bin S; Chintagumpala, Murali

    2013-07-15

    The objective of this study was to evaluate local control and patterns of failure in pediatric patients with low-grade glioma (LGG) who received treatment with intensity-modulated radiation therapy (IMRT). In total, 39 children received IMRT after incomplete resection or disease progression. Three methods of target delineation were used. The first was to delineate the gross tumor volume (GTV) and add a 1-cm margin to create the clinical target volume (CTV) (Method 1; n = 19). The second was to add a 0.5-cm margin around the GTV to create the CTV (Method 2; n = 6). The prescribed dose to the GTV was the same as dose to the CTV for both Methods 1 and 2 (median, 50.4 grays [Gy]). The final method was dose painting, in which a GTV was delineated with a second target volume (2TV) created by adding 1 cm to the GTV (Method 3; n = 14). Different doses were prescribed to the GTV (median, 50.4 Gy) and the 2TV (median, 41.4 Gy). The 8-year progression-free and overall survival rates were 78.2% and 93.7%, respectively. Seven failures occurred, all of which were local in the high-dose (≥95%) region of the IMRT field. On multivariate analysis, age ≤5 years at time of IMRT had a detrimental impact on progression-free survival. IMRT provided local control rates comparable to those provided by 2-dimensional and 3-dimensional radiotherapy. Margins ≥1 cm added to the GTV may not be necessary, because excellent local control was achieved by adding a 0.5-cm margin (Method 2) and by dose painting (Method 3). © 2013 American Cancer Society.

  18. NOTE: MCDE: a new Monte Carlo dose engine for IMRT

    NASA Astrophysics Data System (ADS)

    Reynaert, N.; DeSmedt, B.; Coghe, M.; Paelinck, L.; Van Duyse, B.; DeGersem, W.; DeWagter, C.; DeNeve, W.; Thierens, H.

    2004-07-01

    A new accurate Monte Carlo code for IMRT dose computations, MCDE (Monte Carlo dose engine), is introduced. MCDE is based on BEAMnrc/DOSXYZnrc and consequently the accurate EGSnrc electron transport. DOSXYZnrc is reprogrammed as a component module for BEAMnrc. In this way both codes are interconnected elegantly, while maintaining the BEAM structure and only minimal changes to BEAMnrc.mortran are necessary. The treatment head of the Elekta SLiplus linear accelerator is modelled in detail. CT grids consisting of up to 200 slices of 512 × 512 voxels can be introduced and up to 100 beams can be handled simultaneously. The beams and CT data are imported from the treatment planning system GRATIS via a DICOM interface. To enable the handling of up to 50 × 106 voxels the system was programmed in Fortran95 to enable dynamic memory management. All region-dependent arrays (dose, statistics, transport arrays) were redefined. A scoring grid was introduced and superimposed on the geometry grid, to be able to limit the number of scoring voxels. The whole system uses approximately 200 MB of RAM and runs on a PC cluster consisting of 38 1.0 GHz processors. A set of in-house made scripts handle the parallellization and the centralization of the Monte Carlo calculations on a server. As an illustration of MCDE, a clinical example is discussed and compared with collapsed cone convolution calculations. At present, the system is still rather slow and is intended to be a tool for reliable verification of IMRT treatment planning in the case of the presence of tissue inhomogeneities such as air cavities.

  19. Ionization chamber dosimetry of small photon fields: a Monte Carlo study on stopping-power ratios for radiosurgery and IMRT beams.

    PubMed

    Sánchez-Doblado, F; Andreo, P; Capote, R; Leal, A; Perucha, M; Arráns, R; Núñez, L; Mainegra, E; Lagares, J I; Carrasco, E

    2003-07-21

    Absolute dosimetry with ionization chambers of the narrow photon fields used in stereotactic techniques and IMRT beamlets is constrained by lack of electron equilibrium in the radiation field. It is questionable that stopping-power ratio in dosimetry protocols, obtained for broad photon beams and quasi-electron equilibrium conditions, can be used in the dosimetry of narrow fields while keeping the uncertainty at the same level as for the broad beams used in accelerator calibrations. Monte Carlo simulations have been performed for two 6 MV clinical accelerators (Elekta SL-18 and Siemens Mevatron Primus), equipped with radiosurgery applicators and MLC. Narrow circular and Z-shaped on-axis and off-axis fields, as well as broad IMRT configured beams, have been simulated together with reference 10 x 10 cm2 beams. Phase-space data have been used to generate 3D dose distributions which have been compared satisfactorily with experimental profiles (ion chamber, diodes and film). Photon and electron spectra at various depths in water have been calculated, followed by Spencer-Attix (delta = 10 keV) stopping-power ratio calculations which have been compared to those used in the IAEA TRS-398 code of practice. For water/air and PMMA/air stopping-power ratios, agreements within 0.1% have been obtained for the 10 x 10 cm2 fields. For radiosurgery applicators and narrow MLC beams, the calculated s(w,air) values agree with the reference within +/-0.3%, well within the estimated standard uncertainty of the reference stopping-power ratios (0.5%). Ionization chamber dosimetry of narrow beams at the photon qualities used in this work (6 MV) can therefore be based on stopping-power ratios data in dosimetry protocols. For a modulated 6 MV broad beam used in clinical IMRT, s(w,air) agrees within 0.1% with the value for 10 x 10 cm2, confirming that at low energies IMRT absolute dosimetry can also be based on data for open reference fields. At higher energies (24 MV) the difference in s

  20. SU-F-T-372: Surface and Peripheral Dose in Compensator-Based FFF Beam IMRT

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zhang, D; Feygelman, V; Moros, E

    2016-06-15

    Purpose: Flattening filter free (FFF) beams produce higher dose rates. Combined with compensator IMRT techniques, the dose delivery for each beam can be much shorter compared to the flattened beam MLC-based or compensator-based IMRT. This ‘snap shot’ IMRT delivery is beneficial to patients for tumor motion management. Due to softer energy, surface doses in FFF beam treatment are usually higher than those from flattened beams. Because of less scattering due to no flattening filter, peripheral doses are usually lower in FFF beam treatment. However, in compensator-based IMRT using FFF beams, the compensator is in the beam pathway. Does it introducemore » beam hardening effects and scattering such that the surface dose is lower and peripheral dose is higher compared to FFF beam MLC-based IMRT? Methods: This study applied Monte Carlo techniques to investigate the surface and peripheral doses in compensator-based IMRT using FFF beams and compared it to the MLC-based IMRT using FFF beams and flattened beams. Besides various thicknesses of copper slabs to simulate various thicknesses of compensators, a simple cone-shaped compensator was simulated to mimic a clinical application. The dose distribution in water phantom by the cone-shaped compensator was then simulated by multiple MLC defined FFF and flattened beams with various openings. After normalized to Dmax, the surface and peripheral dose was compared between the FFF beam compensator-based IMRT and FFF/flattened beam MLC-based IMRT. Results: The surface dose at the central 0.5mm depth was close between the compensator and 6FFF MLC dose distributions, and about 8% (of Dmax) higher than the flattened 6MV MLC dose. At 8cm off axis at dmax, the peripheral dose between the 6FFF and flattened 6MV MLC demonstrated similar doses, while the compensator dose was about 1% higher. Conclusion: Compensator does not reduce the surface doses but slightly increases the peripheral doses due to scatter inside compensator.« less

  1. SU-F-T-269: Preliminary Experience of Kuwait Cancer Control Center (KCCC) On IMRT Treatment Planning and Pre-Treatment Verification

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sethuraman, TKR; Sherif, M; Subramanian, N

    Purpose: The complexity of IMRT delivery requires pre-treatment quality assurance and plan verification. KCCC has implemented IMRT clinically in few sites and will extend to all sites. Recently, our Varian linear accelerator and Eclipse planning system were upgraded from Millennium 80 to 120 Multileaf Collimator (MLC) and from v8.6 to 11.0 respectively. Our preliminary experience on the pre-treatment quality assurance verification is discussed. Methods: Eight Breast, Three Prostate and One Hypopharynx cancer patients were planned with step and shoot IMRT. All breast cases were planned before the upgrade with 60% cases treated. The ICRU 83 recommendations were followed for themore » dose prescription and constraints to OAR for all cases. Point dose measurement was done with CIRS cylindrical phantom and PTW 0.125 cc ionization chamber. Measured dose was compared with calculated dose at the point of measurement. Map CHECK diode array phantom was used for the plan verification. Planned and measured doses were compared by applying gamma index of 3% (dose difference) / 3 mm DTA (average distance to agreement). For all cases, a plan is considered to be successful if more than 95% of the tested diodes pass the gamma test. A prostate case was chosen to compare the plan verification before and after the upgrade. Results: Point dose measurement results were in agreement with the calculated doses. The maximum deviation observed was 2.3%. The passing rate of average gamma index was measured higher than 97% for the plan verification of all cases. Similar result was observed for plan verification of the chosen prostate case before and after the upgrade. Conclusion: Our preliminary experience from the obtained results validates the accuracy of our QA process and provides confidence to extend IMRT to all sites in Kuwait.« less

  2. Comparison of IMRT versus 3D-CRT in the treatment of esophagus cancer

    PubMed Central

    Xu, Dandan; Li, Guowen; Li, Hongfei; Jia, Fei

    2017-01-01

    Abstract Background: Esophageal cancer (EC) is a common cancer with high mortality because of its rapid progression and poor prognosis. Radiotherapy is one of the most effective treatments for EC. Three-dimensional conformal radiotherapy (3D-CRT) and intensity-modulated radiotherapy (IMRT) are 2 recently developed radiotherapy techniques. IMRT is believed to be more effective than 3D-CRT in target coverage, dose homogeneity, and reducing toxicity to normal organs. However, these advantages have not been demonstrated in the treatment of EC. This meta-analysis was performed to compare IMRT and 3D-CRT in the treatment of EC in terms of dose–volume histograms and outcomes including survival and toxicity. Methods: A literature search was performed in PubMed, Embase, and the Cochrane library databases from their inceptions to Dec 30, 2016. Two authors independently assessed the included studies and extracted data. The average percent irradiated volumes of adjacent noncancerous organs were calculated and compared between IMRT and 3D-CRT. The odds ratio of overall survival (OS), and radiation pneumonitis and radiation esophagitis was also evaluated. Results: Totally 7 studies were included. Of them, 5 studies (80 patients) were included in the dosimetric comparison, 3 studies (871 patients) were included in the OS analysis, and 2 studies (205 patients) were included in the irradiation toxicity analysis. For lung in patients receiving doses ≥20 Gy and heart in patients receiving dose = 50 Gy, the average irradiated volumes of IMRT were less than those from 3D-CRT. IMRT resulted in a higher OS than 3D-CRT. However, no significant difference was observed in the incidence of radiation pneumonitis and radiation esophagitis between 2 radiotherapy techniques. Conclusion: Our data suggest that IMRT-delivered high radiation dose produces significantly less average percent volumes of irradiated lung and heart than 3D-CRT. IMRT is superior to 3D-CRT in the OS of EC while

  3. Tolerance limits and methodologies for IMRT measurement-based verification QA: Recommendations of AAPM Task Group No. 218.

    PubMed

    Miften, Moyed; Olch, Arthur; Mihailidis, Dimitris; Moran, Jean; Pawlicki, Todd; Molineu, Andrea; Li, Harold; Wijesooriya, Krishni; Shi, Jie; Xia, Ping; Papanikolaou, Nikos; Low, Daniel A

    2018-04-01

    Patient-specific IMRT QA measurements are important components of processes designed to identify discrepancies between calculated and delivered radiation doses. Discrepancy tolerance limits are neither well defined nor consistently applied across centers. The AAPM TG-218 report provides a comprehensive review aimed at improving the understanding and consistency of these processes as well as recommendations for methodologies and tolerance limits in patient-specific IMRT QA. The performance of the dose difference/distance-to-agreement (DTA) and γ dose distribution comparison metrics are investigated. Measurement methods are reviewed and followed by a discussion of the pros and cons of each. Methodologies for absolute dose verification are discussed and new IMRT QA verification tools are presented. Literature on the expected or achievable agreement between measurements and calculations for different types of planning and delivery systems are reviewed and analyzed. Tests of vendor implementations of the γ verification algorithm employing benchmark cases are presented. Operational shortcomings that can reduce the γ tool accuracy and subsequent effectiveness for IMRT QA are described. Practical considerations including spatial resolution, normalization, dose threshold, and data interpretation are discussed. Published data on IMRT QA and the clinical experience of the group members are used to develop guidelines and recommendations on tolerance and action limits for IMRT QA. Steps to check failed IMRT QA plans are outlined. Recommendations on delivery methods, data interpretation, dose normalization, the use of γ analysis routines and choice of tolerance limits for IMRT QA are made with focus on detecting differences between calculated and measured doses via the use of robust analysis methods and an in-depth understanding of IMRT verification metrics. The recommendations are intended to improve the IMRT QA process and establish consistent, and comparable IMRT QA

  4. Automatic learning-based beam angle selection for thoracic IMRT

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Amit, Guy; Marshall, Andrea; Purdie, Thomas G., E-mail: tom.purdie@rmp.uhn.ca

    Purpose: The treatment of thoracic cancer using external beam radiation requires an optimal selection of the radiation beam directions to ensure effective coverage of the target volume and to avoid unnecessary treatment of normal healthy tissues. Intensity modulated radiation therapy (IMRT) planning is a lengthy process, which requires the planner to iterate between choosing beam angles, specifying dose–volume objectives and executing IMRT optimization. In thorax treatment planning, where there are no class solutions for beam placement, beam angle selection is performed manually, based on the planner’s clinical experience. The purpose of this work is to propose and study a computationallymore » efficient framework that utilizes machine learning to automatically select treatment beam angles. Such a framework may be helpful for reducing the overall planning workload. Methods: The authors introduce an automated beam selection method, based on learning the relationships between beam angles and anatomical features. Using a large set of clinically approved IMRT plans, a random forest regression algorithm is trained to map a multitude of anatomical features into an individual beam score. An optimization scheme is then built to select and adjust the beam angles, considering the learned interbeam dependencies. The validity and quality of the automatically selected beams evaluated using the manually selected beams from the corresponding clinical plans as the ground truth. Results: The analysis included 149 clinically approved thoracic IMRT plans. For a randomly selected test subset of 27 plans, IMRT plans were generated using automatically selected beams and compared to the clinical plans. The comparison of the predicted and the clinical beam angles demonstrated a good average correspondence between the two (angular distance 16.8° ± 10°, correlation 0.75 ± 0.2). The dose distributions of the semiautomatic and clinical plans were equivalent in terms of primary

  5. Automated IMRT planning in Pinnacle : A study in head-and-neck cancer.

    PubMed

    Kusters, J M A M; Bzdusek, K; Kumar, P; van Kollenburg, P G M; Kunze-Busch, M C; Wendling, M; Dijkema, T; Kaanders, J H A M

    2017-12-01

    This study evaluates the performance and planning efficacy of the Auto-Planning (AP) module in the clinical version of Pinnacle 9.10 (Philips Radiation Oncology Systems, Fitchburg, WI, USA). Twenty automated intensity-modulated radiotherapy (IMRT) plans were compared with the original manually planned clinical IMRT plans from patients with oropharyngeal cancer. Auto-Planning with IMRT offers similar coverage of the planning target volume as the original manually planned clinical plans, as well as better sparing of the contralateral parotid gland, contralateral submandibular gland, larynx, mandible, and brainstem. The mean dose of the contralateral parotid gland and contralateral submandibular gland could be reduced by 2.5 Gy and 1.7 Gy on average. The number of monitor units was reduced with an average of 143.9 (18%). Hands-on planning time was reduced from 1.5-3 h to less than 1 h. The Auto-Planning module was able to produce clinically acceptable head and neck IMRT plans with consistent quality.

  6. Video-rate optical dosimetry and dynamic visualization of IMRT and VMAT treatment plans in water using Cherenkov radiation

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Glaser, Adam K., E-mail: Adam.K.Glaser@dartmouth.edu, E-mail: Brian.W.Pogue@dartmouth.edu; Andreozzi, Jacqueline M.; Davis, Scott C.

    Purpose: A novel technique for optical dosimetry of dynamic intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT) plans was investigated for the first time by capturing images of the induced Cherenkov radiation in water. Methods: A high-sensitivity, intensified CCD camera (ICCD) was configured to acquire a two-dimensional (2D) projection image of the Cherenkov radiation induced by IMRT and VMAT plans, based on the Task Group 119 (TG-119) C-Shape geometry. Plans were generated using the Varian Eclipse treatment planning system (TPS) and delivered using 6 MV x-rays from a Varian TrueBeam Linear Accelerator (Linac) incident on a water tank dopedmore » with the fluorophore quinine sulfate. The ICCD acquisition was gated to the Linac target trigger pulse to reduce background light artifacts, read out for a single radiation pulse, and binned to a resolution of 512 × 512 pixels. The resulting videos were analyzed temporally for various regions of interest (ROI) covering the planning target volume (PTV) and organ at risk (OAR), and summed to obtain an overall light intensity distribution, which was compared to the expected dose distribution from the TPS using a gamma-index analysis. Results: The chosen camera settings resulted in 23.5 frames per second dosimetry videos. Temporal intensity plots of the PTV and OAR ROIs confirmed the preferential delivery of dose to the PTV versus the OAR, and the gamma analysis yielded 95.9% and 96.2% agreement between the experimentally captured Cherenkov light distribution and expected TPS dose distribution based upon a 3%/3 mm dose difference and distance-to-agreement criterion for the IMRT and VMAT plans, respectively. Conclusions: The results from this initial study demonstrate the first documented use of Cherenkov radiation for video-rate optical dosimetry of dynamic IMRT and VMAT treatment plans. The proposed modality has several potential advantages over alternative methods including the real

  7. Second cancer risk after 3D-CRT, IMRT and VMAT for breast cancer.

    PubMed

    Abo-Madyan, Yasser; Aziz, Muhammad Hammad; Aly, Moamen M O M; Schneider, Frank; Sperk, Elena; Clausen, Sven; Giordano, Frank A; Herskind, Carsten; Steil, Volker; Wenz, Frederik; Glatting, Gerhard

    2014-03-01

    Second cancer risk after breast conserving therapy is becoming more important due to improved long term survival rates. In this study, we estimate the risks for developing a solid second cancer after radiotherapy of breast cancer using the concept of organ equivalent dose (OED). Computer-tomography scans of 10 representative breast cancer patients were selected for this study. Three-dimensional conformal radiotherapy (3D-CRT), tangential intensity modulated radiotherapy (t-IMRT), multibeam intensity modulated radiotherapy (m-IMRT), and volumetric modulated arc therapy (VMAT) were planned to deliver a total dose of 50 Gy in 2 Gy fractions. Differential dose volume histograms (dDVHs) were created and the OEDs calculated. Second cancer risks of ipsilateral, contralateral lung and contralateral breast cancer were estimated using linear, linear-exponential and plateau models for second cancer risk. Compared to 3D-CRT, cumulative excess absolute risks (EAR) for t-IMRT, m-IMRT and VMAT were increased by 2 ± 15%, 131 ± 85%, 123 ± 66% for the linear-exponential risk model, 9 ± 22%, 82 ± 96%, 71 ± 82% for the linear and 3 ± 14%, 123 ± 78%, 113 ± 61% for the plateau model, respectively. Second cancer risk after 3D-CRT or t-IMRT is lower than for m-IMRT or VMAT by about 34% for the linear model and 50% for the linear-exponential and plateau models, respectively. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  8. Hyperfractionated Low-Dose (21 Gy) Radiotherapy for Cranial Skeletal Metastases in Patients With High-Risk Neuroblastoma

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kushner, Brian H., E-mail: kushnerb@mskcc.or; Cheung, Nai-Kong V.; Barker, Christopher A.

    2009-11-15

    Purpose: To present a large experience (73 patients) using a standard radiotherapy (RT) protocol to prevent relapse in cranial sites where measurable metastatic neuroblastoma (NB), an adverse prognostic marker, is common. Methods and Materials: High-risk NB patients with measurable cranial disease at diagnosis or residual cranial disease after induction therapy had those sites irradiated with hyperfractionated 21 Gy; a brain-sparing technique was used for an extensive field. The patients were grouped according to the response to systemic therapy. Thus, when irradiated, Group 1 patients were in complete remission and Group 2 patients had primary refractory disease. Follow-up was from themore » start of cranial RT. Results: At 3 years, the 39 Group 1 patients had a progression-free survival rate of 51%; control of cranial disease was 79%. Two relapses involved irradiated cranial sites. Two other patients relapsed in the irradiated cranial sites 6 and 12 months after a systemic relapse. At 3 years, the 34 Group 2 patients had a progression-free survival rate of 33%; control of cranial disease was 52%. Group 2 included 19 patients who had residual cranial (with or without extracranial) disease. The cranial sites showed major (n = 13), minor (n = 2), or no response (n = 4) to RT. Five patients had progression in the cranial RT field at 10-27 months. Group 2 also included 15 patients who had persistent NB in extracranial, but not cranial, sites. Of these 15 patients, 2 relapsed in the irradiated cranial sites and elsewhere at 8 and 14 months. Cranial RT was well tolerated, with no Grade 2 or greater toxicity. Conclusion: Hyperfractionated 21-Gy cranial RT might help control NB and is feasible without significant toxicity in children.« less

  9. SU-E-J-125: A Novel IMRT Planning Technique to Spare Sacral Bone Marrow in Pelvic Cancer Patients

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    McGuire, S; Bhatia, S; Sun, W

    Purpose: Develop an IMRT planning technique that can preferentially spare sacral bone marrow for pelvic cancer patients. Methods: Six pelvic cancer patients (two each with anal, cervical, and rectal cancer) were enrolled in an IRB approved protocol to obtain FLT PET images at simulation, during, and post chemoradiation therapy. Initially, conventional IMRT plans were created to maintain target coverage and reduce dose to OARs such as bladder, bowel, rectum, and femoral heads. Simulation FLT PET images were used to create IMRT plans to spare bone marrow identified as regions with SUV of 2 or greater (IMRT-BMS) within the pelvic bonesmore » from top of L3 to 5mm below the greater trochanter without compromising PTV coverage or OAR sparing when compared to the initial IMRT plan. IMRT-BMS plans used 8–10 beam angles that surrounded the subject. These plans were used for treatment. Retrospectively, the same simulation FLT PET images were used to create IMRT plans that spared bone marrow located in the sacral pelvic bone region (IMRT-FAN) also without compromising PTV coverage or OAR sparing. IMRT-FAN plans used 16 beam angles every 12° anteriorly from 90° – 270°. Optimization objectives for the sacral bone marrow avoidance region were weighted to reduce ≥V10. Results: IMRT-FAN reduced dose to the sacral bone marrow for all six subjects. The average V5, V10, V20, and V30 differences from the IMRT-BMS plan were −2.2 ± 1.7%, −11.4 ± 3.6%, −17.6 ± 5.1%, and −19.1 ± 8.1% respectively. Average PTV coverage change was 0.5% ± 0.8% from the conventional IMRT plan. Conclusion: An IMRT planning technique that uses beams from the anterior and lateral directions reduced the volume of sacral bone marrow that receives ≤10Gy while maintaining PTV coverage and OAR sparing. Additionally, the volume of sacral bone marrow that received 20 or 30 Gy was also reduced.« less

  10. Optimal Normal Tissue Sparing in Craniospinal Axis Irradiation Using IMRT With Daily Intrafractionally Modulated Junction(s)

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kusters, Johannes M.A.M.; Louwe, Rob J.W.; Kollenburg, Peter G.M. van

    2011-12-01

    Purpose: To develop a treatment technique for craniospinal irradiation using intensity-modulated radiotherapy (IMRT) with improved dose homogeneity at the field junction(s), increased target volume conformity, and minimized dose to the organs at risk (OARs). Methods and Materials: Five patients with high-risk medulloblastoma underwent CT simulation in supine position. For each patient, an IMRT plan with daily intrafractionally modulated junction(s) was generated, as well as a treatment plan based on conventional three-dimensional planning (3DCRT). A dose of 39.6 Gy in 22 daily fractions of 1.8 Gy was prescribed. Dose-volume parameters for target volumes and OARs were compared for the two techniques.more » Results: The maximum dose with IMRT was <107% in all patients. V{sub <95} and V{sub >107} were <1 cm{sup 3} for IMRT compared with 3-9 cm{sup 3} for the craniospinal and 26-43 cm{sup 3} for the spinal-spinal junction with 3DCRT. These observations corresponded with a lower homogeneity index and a higher conformity index for the spinal planning target volume with IMRT. IMRT provided considerable sparing of acute and late reacting tissues. V{sub 75} for the esophagus, gastroesophageal junction, and intestine was 81%, 81%, and 22% with 3DCRT versus 5%, 0%, and 1% with IMRT, respectively. V{sub 75} for the heart and thyroid was 42% and 32% vs. 0% with IMRT. Conclusion: IMRT with daily intrafractionally modulated junction results in a superior target coverage and junction homogeneity compared with 3DCRT. A significant dose reduction can be obtained for acute as well as late-reacting tissues.« less

  11. Rapid hyperfractionated radiotherapy. Clinical results in 178 advanced squamous cell carcinomas of the head and neck

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Nguyen, T.D.; Demange, L.; Froissart, D.

    The authors present a series of 178 patients with Stage III or IV squamous cell carcinoma of the head and neck treated by rapid irradiation using multiple and small fractions per day. An initial group of 91 patients (G1) received a total dose of 72 Gy in 80 sessions and 10 days, according to the following split course schedule: J1 to J5, 36 Gy in 40 sessions, eight daily fractions of .9 Gy separated by 2 hours; J6 to J20, rest period; J21 to J25, same as in J1 except that the spinal cord was shielded. This protocol was alteredmore » for the following 87 patients (G2) by lessening the total dose to 60 to 66 Gy and the number of fractions to 60. The rest period was lengthened to 4 weeks. All patients but five completed the whole program and the minimal follow-up period was 24 months. At the end of irradiation, 121 patients achieved a total remission, but local recurrences occurred in 56%. Moreover, acute intolerance was considered as severe in 34% of G1 patients, and included extensive mucosal necrosis and bleeding. Although this rate was significantly reduced in G2 patients, late complications were observed in 20 of the 25 survivors, and included trismus, cervical sclerosis, and recurrent laryngeal edema. The crude survival rate is 13% at 2 years. Although this study was not randomized, this particular type of accelerated and hyperfractionated combination of irradiation did not really improve the clinical results in advanced carcinoma of the head and neck. Other schedules and probably other tumors, less extended, should be tested.« less

  12. Dosimetric Analysis of Unflattened (FFFB) and Flattened (FB) Photon Beam Energy for Gastric Cancers Using IMRT and VMAT-a Comparative Study.

    PubMed

    Bhushan, Manindra; Yadav, Girigesh; Tripathi, Deepak; Kumar, Lalit; Kishore, Vimal; Dewan, Abhinav; Kumar, Gourav; Wahi, Inderjit Kaur; Gairola, Munish

    2018-03-08

    To evaluate the feasibility of flattening filter free beam (FFFB) for the treatment of gastric tumors and to review their benefits over 6MV flatten beam (6MV_FFB). Fifteen patients with histologically proven gastric carcinoma were selected. CT scans with slice thickness of 0.3 cm were acquired and planning target volume (PTV) and organ at risk (OAR) were delineated. Plans were made retrospectively for each patient for the prescription dose of 45 Gy/25 fractions to the PTV. Four isocentric plans were compared in the present study on Varian TrueBeam linear accelerator (Varian Medical Systems, Palo Alto, CA, USA). PTV D98% was 44.41 ± 0.12, 44.38 ± 0.13, 44.59 ± 0.14, and 44.49 ± 0.19 Gy for IMRT 6MV_FFB, IMRT 6MV_FFFB, VMAT 6MV_FFB, and VMAT 6MV_FFFB respectively. 6MV_FFFB beam minimizes the mean heart dose D mean (P = 0.001). VMAT dominates over IMRT when it came to kidney doses V 12Gy (P = 0.02), V 23Gy (P = 0.015), V 28Gy (P = 0.011), and D max (P < 0.01). VMAT has significantly reduced the doses to kidneys. It was analyzed that 6MV_FFFB significantly reduces the dose to normal tissues (P = 0.006 and P = 0.018). VMAT significantly reduces the TMU, which is required to deliver the similar dose by IMRT (P < 0.01). Unflattened beam spares the organs at risk significantly to avoid the chances of secondary malignancies and reduces the intra-fraction motion during treatment due to provision of higher dose rate. Hence, we conclude that 6MV unflattened beam can be used to treat gastric carcinoma.

  13. Parotid gland sparing IMRT for head and neck cancer improves xerostomia related quality of life

    PubMed Central

    van Rij, CM; Oughlane-Heemsbergen, WD; Ackerstaff, AH; Lamers, EA; Balm, AJM; Rasch, CRN

    2008-01-01

    Background and purpose To assess the impact of intensity modulated radiotherapy (IMRT) versus conventional radiation on late xerostomia and Quality of Life aspects in head and neck cancer patients. Patients and nethods Questionnaires on xerostomia in rest and during meals were sent to all patients treated between January 1999 and December 2003 with a T1-4, N0-2 M0 head and neck cancer, with parotid gland sparing IMRT or conventional bilateral neck irradiation to a dose of at least 60 Gy, who were progression free and had no disseminated disease (n = 192). Overall response was 85% (n = 163); 97% in the IMRT group (n = 75) and 77% in the control group (n = 88) the median follow-up was 2.6 years. The prevalence of complaints was compared between the two groups, correcting for all relevant factors at multivariate ordinal regression analysis. Results Patients treated with IMRT reported significantly less difficulty transporting and swallowing their food and needed less water for a dry mouth during day, night and meals. They also experienced fewer problems with speech and eating in public. Laryngeal cancer patients in general had fewer complaints than oropharynx cancer patients but both groups benefited from IMRT. Within the IMRT group the xerostomia scores were better for those patients with a mean parotid dose to the "spared" parotid below 26 Gy. Conclusion Parotid gland sparing IMRT for head and neck cancer patients improves xerostomia related quality of life compared to conventional radiation both in rest and during meals. Laryngeal cancer patients had fewer complaints but benefited equally compared to oropharyngeal cancer patients from IMRT. PMID:19068126

  14. Incidental Testicular Irradiation From Prostate IMRT: It All Adds Up

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    King, Christopher R., E-mail: crking@stanford.ed; Maxim, Peter G.; Hsu, Annie

    Purpose: To identify the technical aspects of image-guided intensity-modulated radiation therapy (IMRT) for localized prostate cancer that could result in a clinically meaningful incidental dose to the testes. Methods and Materials: We examined three sources that contribute incidental dose to the testes, namely, from internal photon scattering from IMRT small field and large pelvic nodal fields with 6 or 15 MV, from neutrons when >10-MV photons are used, and from daily image-guided fiducial-based portal imaging. Using clinical data from 10 patients who received IMRT for prostate cancer, and thermo-luminescent dosimeter measurements in phantom, we estimated the dose to the testesmore » from each of these sources. Results: A mean testicular dose of 172 and 220 cGy results from internal photon scatter for pelvic nodal fields and 68 and 93 cGy for prostate-only fields, for 6- and 15-MV energies, respectively. For 15-MV photon energies, the mean testicular dose from neutrons is 60 cGy for pelvic fields and 31 cGy for prostate-only fields. From daily portal MV image guidance, the testes-in-field mean dose is 350 cGy, whereas the testes-out-of-field scatter dose is 16 cGy. Dosimetric comparisons between IMRT using 6-MV and 15-MV photon energies are not significantly different. Worst-case scenarios can potentially deliver cumulative incidental mean testicular doses of 630 cGy, whereas best-case scenarios can deliver only 84 cGy. Conclusions: Incidental dose to the testes from prostate IMRT can be minimized by opting to restrict the use of elective pelvic nodal fields, by choosing photon energies <10 MV, and by using the smallest port sizes necessary for daily image guidance.« less

  15. Monte Carlo simulations to replace film dosimetry in IMRT verification.

    PubMed

    Goetzfried, Thomas; Rickhey, Mark; Treutwein, Marius; Koelbl, Oliver; Bogner, Ludwig

    2011-01-01

    Patient-specific verification of intensity-modulated radiation therapy (IMRT) plans can be done by dosimetric measurements or by independent dose or monitor unit calculations. The aim of this study was the clinical evaluation of IMRT verification based on a fast Monte Carlo (MC) program with regard to possible benefits compared to commonly used film dosimetry. 25 head-and-neck IMRT plans were recalculated by a pencil beam based treatment planning system (TPS) using an appropriate quality assurance (QA) phantom. All plans were verified both by film and diode dosimetry and compared to MC simulations. The irradiated films, the results of diode measurements and the computed dose distributions were evaluated, and the data were compared on the basis of gamma maps and dose-difference histograms. Average deviations in the high-dose region between diode measurements and point dose calculations performed with the TPS and MC program were 0.7 ± 2.7% and 1.2 ± 3.1%, respectively. For film measurements, the mean gamma values with 3% dose difference and 3mm distance-to-agreement were 0.74 ± 0.28 (TPS as reference) with dose deviations up to 10%. Corresponding values were significantly reduced to 0.34 ± 0.09 for MC dose calculation. The total time needed for both verification procedures is comparable, however, by far less labor intensive in the case of MC simulations. The presented study showed that independent dose calculation verification of IMRT plans with a fast MC program has the potential to eclipse film dosimetry more and more in the near future. Thus, the linac-specific QA part will necessarily become more important. In combination with MC simulations and due to the simple set-up, point-dose measurements for dosimetric plausibility checks are recommended at least in the IMRT introduction phase. Copyright © 2010. Published by Elsevier GmbH.

  16. VMAT testing for an Elekta accelerator

    PubMed Central

    Sweeney, Larry E.; Marshall, Edward I.; Mahendra, Saikanth

    2012-01-01

    Volumetric‐modulated arc therapy (VMAT) has been shown to be able to deliver plans equivalent to intensity‐modulated radiation therapy (IMRT) in a fraction of the treatment time. This improvement is important for patient immobilization/ localization compliance due to comfort and treatment duration, as well as patient throughput. Previous authors have suggested commissioning methods for this modality. Here, we extend the methods reported for the Varian RapidArc system (which tested individual system components) to the Elekta linear accelerator, using custom files built using the Elekta iComCAT software. We also extend the method reported for VMAT commissioning of the Elekta accelerator by verifying maximum values of parameters (gantry speed, multileaf collimator (MLC) speed, and backup jaw speed), investigating: 1) beam profiles as a function of dose rate during an arc, 2) over/under dosing due to MLC reversals, and 3) over/under dosing at changing dose rate junctions. Equations for construction of the iComCAT files are given. Results indicate that the beam profile for lower dose rates varies less than 3% from that of the maximum dose rate, with no difference during an arc. The gantry, MLC, and backup jaw maximum speed are internally consistent. The monitor unit chamber is stable over the MUs and gantry movement conditions expected. MLC movement and position during VMAT delivery are within IMRT tolerances. Dose rate, gantry speed, and MLC speed are accurately controlled. Over/under dosing at junctions of MLC reversals or dose rate changes are within clinical acceptability. PACS numbers: 87.55.de, 87.55.Qr, 87.56.bd PMID:22402389

  17. After low and high dose-rate interstitial brachytherapy followed by IMRT radiotherapy for intermediate and high risk prostate cancer.

    PubMed

    Nakamura, Satoshi; Murakami, Naoya; Inaba, Koji; Wakita, Akihisa; Kobayashi, Kazuma; Takahashi, Kana; Okamoto, Hiroyuki; Umezawa, Rei; Morota, Madoka; Sumi, Minako; Igaki, Hiroshi; Ito, Yoshinori; Itami, Jun

    2016-05-03

    The study aimed to compare urinary symptoms in patients with clinically localized prostate cancer after a combination of either low-dose-rate or high-dose-rate interstitial brachytherapy along with intensity-modulated radiation therapy (LDR-ISBT + IMRT or HDR-ISBT + IMRT). From June 2009 to April 2014, 16 and 22 patients were treated with LDR-ISBT + IMRT and HDR-ISBT + IMRT, respectively. No patient from these groups was excluded from this study. The prescribed dose of LDR-ISBT, HDR-ISBT, and IMRT was 115 Gy, 20 Gy in 2 fractions, and 46 Gy in 23 fractions, respectively. Obstructive and irritative urinary symptoms were assessed by the International Prostate Symptom Score (IPSS) examined before and after treatments. After ISBT, IPSS was evaluated in the 1st and 4th weeks, then every 2-3 months for the 1st year, and every 6 months thereafter. The median follow-up of the patients treated with LDR-ISBT + IMRT and HDR-ISBT + IMRT was 1070.5 days and 1048.5 days, respectively (p = 0.321). The IPSS-increment in the LDR-ISBT + IMRT group was greater than that in the HDR-ISBT + IMRT between 91 and 180 days after ISBT (p = 0.015). In the LDR-ISBT + IMRT group, the IPSS took longer time to return to the initial level than in the HDR-ISBT + IMRT group (in LDR-ISBT + IMRT group, the recovery time was 90 days later). The dose to urethra showed a statistically significant association with the IPSS-increment in the irritative urinary symptoms (p = 0.011). Clinical outcomes were comparable between both the groups. Both therapeutic modalities are safe and well suited for patients with clinically localized prostate cancer; however, it took patients longer to recover from LDR-ISBT + IMRT than from HDR-ISBT + IMRT. It is possible that fast dose delivery induced early symptoms and early recovery, while gradual dose delivery induced late symptoms and late recovery. Urethral dose reductions were associated with small increments in IPSS.

  18. Multiadaptive Plan (MAP) IMRT to Accommodate Independent Movement of the Prostate and Pelvic Lymph Nodes

    DTIC Science & Technology

    2013-06-01

    08-1-0358 TITLE: Multiadaptive Plan (MAP) IMRT to Accommodate Independent Movement of the Prostate and Pelvic Lymph Nodes PRINCIPAL...AND SUBTITLE Multi-Adaptive Plan (MAP) IMRT to Accommodate Independent 5a. CONTRACT NUMBER W81XWH-08-1-0358 Movement of the Prostate and...multi-adaptive plan (MAP) IMRT to accommodate independent movement of the two targeted tumor volumes. In this project, we evaluated two adaptive

  19. SU-E-T-59: A Novel Multi-Beam Dynamic IMRT with Fixed-Jaw Technique for Left Breast Cancer Patients with Regional Lymph Nodes Radiotherapy

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wang, J; Yang, Z; Hu, W

    2015-06-15

    Purpose: This study was to investigate the dosimetric benefit of a novel intensity modulated radiation therapy (IMRT) technique for irradiating the left breast and regional lymph node (RLN). Methods: The breast and RLN (internal mammary node and periclavicular node) and normal tissue were contoured for 16 consecutive left-sided breast cancer patients previously treated with RT after lumpectomy. Nine equi-spaced fields IMRT (9 -field IMRT), tangential multi-beam IMRT (tangential-IMRT) and IMRT with fixed-jaw technique (FJT-IMRT) were developed and compared with three-dimensional conformal RT (3DCRT). Prescribed dose was 50 Gy in 25 fractions. Dose distributions and dose volume histograms were used tomore » evaluate plans. Results: All IMRTs achieved similar target coverage and substantially reduced heart V30 and V20 compared to the 3DCRT. The average heart mean dose had different changes, which were 9.0Gy for 9-field IMRT, 5.7Gy for tangential-IMRT and 4.2Gy for FJT-IMRT. For the contralateral lung and breast, the 9-field IMRT has the highest mean dose; and the FJT-IMRT and tangential-IMRT had similar lower value. For the thyroid, both 9-field IMRT and FJT-IMRT had similar V30 (20% and 22%) and were significantly lower than that of 3DCRT (34%) and tangential-IMRT (46%). Moreover, the thyroid mean dose of FJT-IMRT is the lowest. For cervical esophagus and humeral head, the FJT-IMRT also had the best sparing. Conclusion: All 9-field IMRT, tangential-IMRT and FJT-IMRT had superiority for targets coverage and substantially reduced the heart volume of high dose irradiation. The FJT-IMRT showed advantages of avoiding the contralateral breast and lung irradiation and decreasing the thyroid, humeral head and cervical esophagus radiation dose at the expense of a slight monitor units (MUs) increasing.« less

  20. A case study of IMRT planning (Plan B) subsequent to a previously treated IMRT plan (Plan A)

    NASA Astrophysics Data System (ADS)

    Cao, F.; Leong, C.; Schroeder, J.; Lee, B.

    2014-03-01

    Background and purpose: Treatment of the contralateral neck after previous ipsilateral intensity modulated radiation therapy (IMRT) for head and neck cancer is a challenging problem. We have developed a technique that limits the cumulative dose to the spinal cord and brainstem while maximizing coverage of a planning target volume (PTV) in the contralateral neck. Our case involves a patient with right tonsil carcinoma who was given ipsilateral IMRT with 70Gy in 35 fractions (Plan A). A left neck recurrence was detected 14 months later. The patient underwent a neck dissection followed by postoperative left neck radiation to a dose of 66 Gy in 33 fractions (Plan B). Materials and Methods: The spinal cord-brainstem margin (SCBM) was defined as the spinal cord and brainstem with a 1.0 cm margin. Plan A was recalculated on the postoperative CT scan but the fluence outside of SCBM was deleted. A further modification of Plan A resulted in a base plan that was summed with Plan B to evaluate the cumulative dose received by the spinal cord and brainstem. Plan B alone was used to evaluate for coverage of the contralateral neck PTV. Results: The maximum cumulative doses to the spinal cord with 0.5cm margin and brainstem with 0.5cm margin were 51.96 Gy and 45.60 Gy respectively. For Plan B, 100% of the prescribed dose covered 95% of PTVb1. Conclusion: The use of a modified ipsilateral IMRT plan as a base plan is an effective way to limit the cumulative dose to the spinal cord and brainstem while enabling coverage of a PTV in the contralateral neck.

  1. Dosimetric comparison of helical tomotherapy, RapidArc, and a novel IMRT & Arc technique for esophageal carcinoma.

    PubMed

    Martin, Spencer; Chen, Jeff Z; Rashid Dar, A; Yartsev, Slav

    2011-12-01

    To compare radiotherapy treatment plans for mid- and distal-esophageal cancer with primary involvement of the gastroesophageal (GE) junction using a novel IMRT & Arc technique (IMRT & Arc), helical tomotherapy (HT), and RapidArc (RA1 and RA2). Eight patients treated on HT for locally advanced esophageal cancer with radical intent were re-planned for RA and IMRT&Arc. RA plans employed single and double arcs (RA1 and RA2, respectively), while IMRT&Arc plans had four fixed-gantry IMRT fields and a conformal arc. Dose-volume histogram statistics, dose uniformity, and dose homogeneity were analyzed to compare treatment plans. RA2 plans showed significant improvement over RA1 plans in terms of OAR dose and PTV dose uniformity and homogeneity. HT plan provided best dose uniformity (p=0.001) and dose homogeneity (p=0.002) to planning target volume (PTV), while IMRT&Arc and RA2 plans gave lowest dose to lungs among four radiotherapy techniques with acceptable PTV dose coverage. Mean V(10) of the lungs was significantly reduced by the RA2 plans compared to IMRT&Arc (40.3%, p=0.001) and HT (66.2%, p<0.001) techniques. Mean V(15) of the lungs for the RA2 plans also showed significant improvement over the IMRT&Arc (25.2%, p=0.042) and HT (34.8%, p=0.027) techniques. These improvements came at the cost of higher doses to the heart volume compared to HT and IMRT&Arc techniques. Mean lung dose (MLD) for the IMRT&Arc technique (21.2 ± 5.0% of prescription dose) was significantly reduced compared to HT (26.3%, p=0.004), RA1 (23.3%, p=0.028), and RA2 (23.2%, p=0.017) techniques. The IMRT&Arc technique is a good option for treating esophageal cancer with thoracic involvement. It achieved optimal low dose to the lungs and heart with acceptable PTV coverage. HT is a good option for treating esophageal cancer with little thoracic involvement as it achieves superior dose conformality and uniformity. The RA2 technique provided for improved treatment plans using additional arcs with low

  2. MO-FG-202-09: Virtual IMRT QA Using Machine Learning: A Multi-Institutional Validation

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Valdes, G; Scheuermann, R; Solberg, T

    Purpose: To validate a machine learning approach to Virtual IMRT QA for accurately predicting gamma passing rates using different QA devices at different institutions. Methods: A Virtual IMRT QA was constructed using a machine learning algorithm based on 416 IMRT plans, in which QA measurements were performed using diode-array detectors and a 3%local/3mm with 10% threshold. An independent set of 139 IMRT measurements from a different institution, with QA data based on portal dosimetry using the same gamma index and 10% threshold, was used to further test the algorithm. Plans were characterized by 90 different complexity metrics. A weighted poisonmore » regression with Lasso regularization was trained to predict passing rates using the complexity metrics as input. Results: In addition to predicting passing rates with 3% accuracy for all composite plans using diode-array detectors, passing rates for portal dosimetry on per-beam basis were predicted with an error <3.5% for 120 IMRT measurements. The remaining measurements (19) had large areas of low CU, where portal dosimetry has larger disagreement with the calculated dose and, as such, large errors were expected. These beams need to be further modeled to correct the under-response in low dose regions. Important features selected by Lasso to predict gamma passing rates were: complete irradiated area outline (CIAO) area, jaw position, fraction of MLC leafs with gaps smaller than 20 mm or 5mm, fraction of area receiving less than 50% of the total CU, fraction of the area receiving dose from penumbra, weighted Average Irregularity Factor, duty cycle among others. Conclusion: We have demonstrated that the Virtual IMRT QA can predict passing rates using different QA devices and across multiple institutions. Prediction of QA passing rates could have profound implications on the current IMRT process.« less

  3. Transit dosimetry in IMRT with an a-Si EPID in direct detection configuration

    NASA Astrophysics Data System (ADS)

    Sabet, Mahsheed; Rowshanfarzad, Pejman; Vial, Philip; Menk, Frederick W.; Greer, Peter B.

    2012-08-01

    In this study an amorphous silicon electronic portal imaging device (a-Si EPID) converted to direct detection configuration was investigated as a transit dosimeter for intensity modulated radiation therapy (IMRT). After calibration to dose and correction for a background offset signal, the EPID-measured absolute IMRT transit doses for 29 fields were compared to a MatriXX two-dimensional array of ionization chambers (as reference) using Gamma evaluation (3%, 3 mm). The MatriXX was first evaluated as reference for transit dosimetry. The accuracy of EPID measurements was also investigated by comparison of point dose measurements by an ionization chamber on the central axis with slab and anthropomorphic phantoms in a range of simple to complex fields. The uncertainty in ionization chamber measurements in IMRT fields was also investigated by its displacement from the central axis and comparison with the central axis measurements. Comparison of the absolute doses measured by the EPID and MatriXX with slab phantoms in IMRT fields showed that on average 96.4% and 97.5% of points had a Gamma index<1 in head and neck and prostate fields, respectively. For absolute dose comparisons with anthropomorphic phantoms, the values changed to an average of 93.6%, 93.7% and 94.4% of points with Gamma index<1 in head and neck, brain and prostate fields, respectively. Point doses measured by the EPID and ionization chamber were within 3% difference for all conditions. The deviations introduced in the response of the ionization chamber in IMRT fields were<1%. The direct EPID performance for transit dosimetry showed that it has the potential to perform accurate, efficient and comprehensive in vivo dosimetry for IMRT.

  4. Quality correction factors of composite IMRT beam deliveries: theoretical considerations.

    PubMed

    Bouchard, Hugo

    2012-11-01

    In the scope of intensity modulated radiation therapy (IMRT) dosimetry using ionization chambers, quality correction factors of plan-class-specific reference (PCSR) fields are theoretically investigated. The symmetry of the problem is studied to provide recommendable criteria for composite beam deliveries where correction factors are minimal and also to establish a theoretical limit for PCSR delivery k(Q) factors. The concept of virtual symmetric collapsed (VSC) beam, being associated to a given modulated composite delivery, is defined in the scope of this investigation. Under symmetrical measurement conditions, any composite delivery has the property of having a k(Q) factor identical to its associated VSC beam. Using this concept of VSC, a fundamental property of IMRT k(Q) factors is demonstrated in the form of a theorem. The sensitivity to the conditions required by the theorem is thoroughly examined. The theorem states that if a composite modulated beam delivery produces a uniform dose distribution in a volume V(cyl) which is symmetric with the cylindrical delivery and all beams fulfills two conditions in V(cyl): (1) the dose modulation function is unchanged along the beam axis, and (2) the dose gradient in the beam direction is constant for a given lateral position; then its associated VSC beam produces no lateral dose gradient in V(cyl), no matter what beam modulation or gantry angles are being used. The examination of the conditions required by the theorem lead to the following results. The effect of the depth-dose gradient not being perfectly constant with depth on the VSC beam lateral dose gradient is found negligible. The effect of the dose modulation function being degraded with depth on the VSC beam lateral dose gradient is found to be only related to scatter and beam hardening, as the theorem holds also for diverging beams. The use of the symmetry of the problem in the present paper leads to a valuable theorem showing that k(Q) factors of composite IMRT

  5. IMRT delivers lower radiation doses to dental structures than 3DRT in head and neck cancer patients.

    PubMed

    Fregnani, Eduardo Rodrigues; Parahyba, Cláudia Joffily; Morais-Faria, Karina; Fonseca, Felipe Paiva; Ramos, Pedro Augusto Mendes; de Moraes, Fábio Yone; da Conceição Vasconcelos, Karina Gondim Moutinho; Menegussi, Gisela; Santos-Silva, Alan Roger; Brandão, Thais B

    2016-09-07

    Radiotherapy (RT) is frequently used in the treatment of head and neck cancer, but different side-effects are frequently reported, including a higher frequency of radiation-related caries, what may be consequence of direct radiation to dental tissue. The intensity-modulated radiotherapy (IMRT) was developed to improve tumor control and decrease patient's morbidity by delivering radiation beams only to tumor shapes and sparing normal tissue. However, teeth are usually not included in IMRT plannings and the real efficacy of IMRT in the dental context has not been addressed. Therefore, the aim of this study is to assess whether IMRT delivers lower radiation doses to dental structures than conformal 3D radiotherapy (3DRT). Radiation dose delivery to dental structures of 80 patients treated for head and neck cancers (oral cavity, tongue, nasopharynx and oropharynx) with IMRT (40 patients) and 3DRT (40 patients) were assessed by individually contouring tooth crowns on patients' treatment plans. Clinicopathological data were retrieved from patients' medical files. The average dose of radiation to teeth delivered by IMRT was significantly lower than with 3DRT (p = 0.007); however, only patients affected by nasopharynx and oral cavity cancers demonstrated significantly lower doses with IMRT (p = 0.012 and p = 0.011, respectively). Molars received more radiation with both 3DRT and IMRT, but the latter delivered significantly lower radiation in this group of teeth (p < 0.001), whereas no significant difference was found for the other dental groups. Maxillary teeth received lower doses than mandibular teeth, but only IMRT delivered significantly lower doses (p = 0.011 and p = 0.003). Ipsilateral teeth received higher doses than contralateral teeth with both techniques and IMRT delivered significantly lower radiation than 3DRT for contralateral dental structures (p < 0.001). IMRT delivered lower radiation doses to teeth than 3DRT, but only for some

  6. Dosimetry investigation of MOSFET for clinical IMRT dose verification.

    PubMed

    Deshpande, Sudesh; Kumar, Rajesh; Ghadi, Yogesh; Neharu, R M; Kannan, V

    2013-06-01

    In IMRT, patient-specific dose verification is followed regularly at each centre. Simple and efficient dosimetry techniques play a very important role in routine clinical dosimetry QA. The MOSFET dosimeter offers several advantages over the conventional dosimeters such as its small detector size, immediate readout, immediate reuse, multiple point dose measurements. To use the MOSFET as routine clinical dosimetry system for pre-treatment dose verification in IMRT, a comprehensive set of experiments has been conducted, to investigate its linearity, reproducibility, dose rate effect and angular dependence for 6 MV x-ray beam. The MOSFETs shows a linear response with linearity coefficient of 0.992 for a dose range of 35 cGy to 427 cGy. The reproducibility of the MOSFET was measured by irradiating the MOSFET for ten consecutive irradiations in the dose range of 35 cGy to 427 cGy. The measured reproducibility of MOSFET was found to be within 4% up to 70 cGy and within 1.4% above 70 cGy. The dose rate effect on the MOSFET was investigated in the dose rate range 100 MU/min to 600 MU/min. The response of the MOSFET varies from -1.7% to 2.1%. The angular responses of the MOSFETs were measured at 10 degrees intervals from 90 to 270 degrees in an anticlockwise direction and normalized at gantry angle zero and it was found to be in the range of 0.98 ± 0.014 to 1.01 ± 0.014. The MOSFETs were calibrated in a phantom which was later used for IMRT verification. The measured calibration coefficients were found to be 1 mV/cGy and 2.995 mV/cGy in standard and high sensitivity mode respectively. The MOSFETs were used for pre-treatment dose verification in IMRT. Nine dosimeters were used for each patient to measure the dose in different plane. The average variation between calculated and measured dose at any location was within 3%. Dose verification using MOSFET and IMRT phantom was found to quick and efficient and well suited for a busy radiotherapy

  7. From analytic inversion to contemporary IMRT optimization: Radiation therapy planning revisited from a mathematical perspective

    PubMed Central

    Censor, Yair; Unkelbach, Jan

    2011-01-01

    In this paper we look at the development of radiation therapy treatment planning from a mathematical point of view. Historically, planning for Intensity-Modulated Radiation Therapy (IMRT) has been considered as an inverse problem. We discuss first the two fundamental approaches that have been investigated to solve this inverse problem: Continuous analytic inversion techniques on one hand, and fully-discretized algebraic methods on the other hand. In the second part of the paper, we review another fundamental question which has been subject to debate from the beginning of IMRT until the present day: The rotation therapy approach versus fixed angle IMRT. This builds a bridge from historic work on IMRT planning to contemporary research in the context of Intensity-Modulated Arc Therapy (IMAT). PMID:21616694

  8. SU-E-T-105: An FMEA Survey of Intensity Modulated Radiation Therapy (IMRT) Step and Shoot Dose Delivery Failure Modes

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Faught, J Tonigan; Johnson, J; Stingo, F

    2015-06-15

    Purpose: To assess the perception of TG-142 tolerance level dose delivery failures in IMRT and the application of FMEA process to this specific aspect of IMRT. Methods: An online survey was distributed to medical physicists worldwide that briefly described 11 different failure modes (FMs) covered by basic quality assurance in step- and-shoot IMRT at or near TG-142 tolerance criteria levels. For each FM, respondents estimated the worst case H&N patient percent dose error and FMEA scores for Occurrence, Detectability, and Severity. Demographic data was also collected. Results: 181 individual and three group responses were submitted. 84% were from North America.more » Most (76%) individual respondents performed at least 80% clinical work and 92% were nationally certified. Respondent medical physics experience ranged from 2.5–45 years (average 18 years). 52% of individual respondents were at least somewhat familiar with FMEA, while 17% were not familiar. Several IMRT techniques, treatment planning systems and linear accelerator manufacturers were represented. All FMs received widely varying scores ranging from 1–10 for occurrence, at least 1–9 for detectability, and at least 1–7 for severity. Ranking FMs by RPN scores also resulted in large variability, with each FM being ranked both most risky (1st ) and least risky (11th) by different respondents. On average MLC modeling had the highest RPN scores. Individual estimated percent dose errors and severity scores positively correlated (p<0.10) for each FM as expected. No universal correlations were found between the demographic information collected and scoring, percent dose errors, or ranking. Conclusion: FMs investigated overall were evaluated as low to medium risk, with average RPNs less than 110. The ranking of 11 FMs was not agreed upon by the community. Large variability in FMEA scoring may be caused by individual interpretation and/or experience, thus reflecting the subjective nature of the FMEA tool.« less

  9. Analysis of Local Control in Patients Receiving IMRT for Resected Pancreatic Cancers

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Yovino, Susannah; Maidment, Bert W.; Herman, Joseph M.

    2012-07-01

    Purpose: Intensity-modulated radiotherapy (IMRT) is increasingly incorporated into therapy for pancreatic cancer. A concern regarding this technique is the potential for geographic miss and decreased local control. We analyzed patterns of first failure among patients treated with IMRT for resected pancreatic cancer. Methods and Materials: Seventy-one patients who underwent resection and adjuvant chemoradiation for pancreas cancer are included in this report. IMRT was used for all to a median dose of 50.4 Gy. Concurrent chemotherapy was 5-FU-based in 72% of patients and gemcitabine-based in 28%. Results: At median follow-up of 24 months, 49/71 patients (69%) had failed. The predominant failuremore » pattern was distant metastases in 35/71 patients (49%). The most common site of metastases was the liver. Fourteen patients (19%) developed locoregional failure in the tumor bed alone in 5 patients, regional nodes in 4 patients, and concurrently with metastases in 5 patients. Median overall survival (OS) was 25 months. On univariate analysis, nodal status, margin status, postoperative CA 19-9 level, and weight loss during treatment were predictive for OS. On multivariate analysis, higher postoperative CA19-9 levels predicted for worse OS on a continuous basis (p < 0.01). A trend to worse OS was seen among patients with more weight loss during therapy (p = 0.06). Patients with positive nodes and positive margins also had significantly worse OS (HR for death 2.8, 95% CI 1.1-7.5; HR for death 2.6, 95% CI 1.1-6.2, respectively). Grade 3-4 nausea and vomiting was seen in 8% of patients. Late complication of small bowel obstruction occurred in 4 (6%) patients. Conclusions: This is the first comprehensive report of patterns of failure among patients treated with adjuvant IMRT for pancreas cancer. IMRT was not associated with an increase in local recurrences in our cohort. These data support the use of IMRT in the recently activated EORTC/US Intergroup/RTOG 0848 adjuvant

  10. Comparison of dental health of patients with head and neck cancer receiving IMRT vs conventional radiation.

    PubMed

    Duarte, Victor M; Liu, Yuan F; Rafizadeh, Sassan; Tajima, Tracey; Nabili, Vishad; Wang, Marilene B

    2014-01-01

    To analyze the dental health of patients with head and neck cancer who received comprehensive dental care after intensity-modulated radiation therapy (IMRT) compared with radiation therapy (RT). Historical cohort study. Veteran Affairs (VA) hospital. In total, 158 patients at a single VA hospital who were treated with RT or IMRT between 2003 and 2011 were identified. A complete dental evaluation was performed prior to radiation treatment, including periodontal probing, tooth profile, cavity check, and mobility. The dental treatment plan was formulated to eliminate current and potential dental disease. The rates of dental extractions, infections, caries, mucositis, xerostomia, and osteoradionecrosis (ORN) were analyzed, and a comparison was made between patients treated with IMRT and those treated with RT. Of the 158 patients, 99 were treated with RT and 59 were treated with IMRT. Compared with those treated with IMRT, significantly more patients treated with RT exhibited xerostomia (46.5% vs 16.9%; P < .001; odds ratio [OR], 0.24; 95% confidence interval [CI], 0.11-0.52), mucositis (46.5% vs 16.9%; P < .001; OR, 0.24; 95% CI, 0.11-0.52), and ORN (10.1% vs 0%; P = .014; OR, 0.07; 95% CI, 0.00-1.21). However, significantly more patients treated with IMRT were edentulous by the conclusion of radiation treatment (32.2% vs 11.1%; P = .002; OR, 3.8; 95% CI, 1.65-8.73). Patients who were treated with IMRT had fewer instances of dental disease, more salivary flow, and fewer requisite posttreatment extractions compared with those treated with RT. The number of posttreatment extractions has been reduced with the advent of IMRT and more so with a complete dental evaluation prior to treatment.

  11. Esophagus and Contralateral Lung-Sparing IMRT for Locally Advanced Lung Cancer in the Community Hospital Setting.

    PubMed

    Kao, Johnny; Pettit, Jeffrey; Zahid, Soombal; Gold, Kenneth D; Palatt, Terry

    2015-01-01

    The optimal technique for performing lung IMRT remains poorly defined. We hypothesize that improved dose distributions associated with normal tissue-sparing IMRT can allow safe dose escalation resulting in decreased acute and late toxicity. We performed a retrospective analysis of 82 consecutive lung cancer patients treated with curative intent from 1/10 to 9/14. From 1/10 to 4/12, 44 patients were treated with the community standard of three-dimensional conformal radiotherapy or IMRT without specific esophagus or contralateral lung constraints (standard RT). From 5/12 to 9/14, 38 patients were treated with normal tissue-sparing IMRT with selective sparing of contralateral lung and esophagus. The study endpoints were dosimetry, toxicity, and overall survival. Despite higher mean prescribed radiation doses in the normal tissue-sparing IMRT cohort (64.5 vs. 60.8 Gy, p = 0.04), patients treated with normal tissue-sparing IMRT had significantly lower lung V20, V10, V5, mean lung, esophageal V60, and mean esophagus doses compared to patients treated with standard RT (p ≤ 0.001). Patients in the normal tissue-sparing IMRT group had reduced acute grade ≥3 esophagitis (0 vs. 11%, p < 0.001), acute grade ≥2 weight loss (2 vs. 16%, p = 0.04), and late grade ≥2 pneumonitis (7 vs. 21%, p = 0.02). The 2-year overall survival was 52% with normal tissue-sparing IMRT arm compared to 28% for standard RT (p = 0.015). These data provide proof of principle that suboptimal radiation dose distributions are associated with significant acute and late lung and esophageal toxicity that may result in hospitalization or even premature mortality. Strict attention to contralateral lung and esophageal dose-volume constraints are feasible in the community hospital setting without sacrificing disease control.

  12. IMRT QA: Selecting gamma criteria based on error detection sensitivity

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Steers, Jennifer M.; Fraass, Benedick A., E-mail: benedick.fraass@cshs.org

    Purpose: The gamma comparison is widely used to evaluate the agreement between measurements and treatment planning system calculations in patient-specific intensity modulated radiation therapy (IMRT) quality assurance (QA). However, recent publications have raised concerns about the lack of sensitivity when employing commonly used gamma criteria. Understanding the actual sensitivity of a wide range of different gamma criteria may allow the definition of more meaningful gamma criteria and tolerance limits in IMRT QA. We present a method that allows the quantitative determination of gamma criteria sensitivity to induced errors which can be applied to any unique combination of device, delivery technique,more » and software utilized in a specific clinic. Methods: A total of 21 DMLC IMRT QA measurements (ArcCHECK®, Sun Nuclear) were compared to QA plan calculations with induced errors. Three scenarios were studied: MU errors, multi-leaf collimator (MLC) errors, and the sensitivity of the gamma comparison to changes in penumbra width. Gamma comparisons were performed between measurements and error-induced calculations using a wide range of gamma criteria, resulting in a total of over 20 000 gamma comparisons. Gamma passing rates for each error class and case were graphed against error magnitude to create error curves in order to represent the range of missed errors in routine IMRT QA using 36 different gamma criteria. Results: This study demonstrates that systematic errors and case-specific errors can be detected by the error curve analysis. Depending on the location of the error curve peak (e.g., not centered about zero), 3%/3 mm threshold = 10% at 90% pixels passing may miss errors as large as 15% MU errors and ±1 cm random MLC errors for some cases. As the dose threshold parameter was increased for a given %Diff/distance-to-agreement (DTA) setting, error sensitivity was increased by up to a factor of two for select cases. This increased sensitivity with increasing

  13. IMRT QA: Selecting gamma criteria based on error detection sensitivity.

    PubMed

    Steers, Jennifer M; Fraass, Benedick A

    2016-04-01

    The gamma comparison is widely used to evaluate the agreement between measurements and treatment planning system calculations in patient-specific intensity modulated radiation therapy (IMRT) quality assurance (QA). However, recent publications have raised concerns about the lack of sensitivity when employing commonly used gamma criteria. Understanding the actual sensitivity of a wide range of different gamma criteria may allow the definition of more meaningful gamma criteria and tolerance limits in IMRT QA. We present a method that allows the quantitative determination of gamma criteria sensitivity to induced errors which can be applied to any unique combination of device, delivery technique, and software utilized in a specific clinic. A total of 21 DMLC IMRT QA measurements (ArcCHECK®, Sun Nuclear) were compared to QA plan calculations with induced errors. Three scenarios were studied: MU errors, multi-leaf collimator (MLC) errors, and the sensitivity of the gamma comparison to changes in penumbra width. Gamma comparisons were performed between measurements and error-induced calculations using a wide range of gamma criteria, resulting in a total of over 20 000 gamma comparisons. Gamma passing rates for each error class and case were graphed against error magnitude to create error curves in order to represent the range of missed errors in routine IMRT QA using 36 different gamma criteria. This study demonstrates that systematic errors and case-specific errors can be detected by the error curve analysis. Depending on the location of the error curve peak (e.g., not centered about zero), 3%/3 mm threshold = 10% at 90% pixels passing may miss errors as large as 15% MU errors and ±1 cm random MLC errors for some cases. As the dose threshold parameter was increased for a given %Diff/distance-to-agreement (DTA) setting, error sensitivity was increased by up to a factor of two for select cases. This increased sensitivity with increasing dose threshold was consistent

  14. From analytic inversion to contemporary IMRT optimization: radiation therapy planning revisited from a mathematical perspective.

    PubMed

    Censor, Yair; Unkelbach, Jan

    2012-04-01

    In this paper we look at the development of radiation therapy treatment planning from a mathematical point of view. Historically, planning for Intensity-Modulated Radiation Therapy (IMRT) has been considered as an inverse problem. We discuss first the two fundamental approaches that have been investigated to solve this inverse problem: Continuous analytic inversion techniques on one hand, and fully-discretized algebraic methods on the other hand. In the second part of the paper, we review another fundamental question which has been subject to debate from the beginning of IMRT until the present day: The rotation therapy approach versus fixed angle IMRT. This builds a bridge from historic work on IMRT planning to contemporary research in the context of Intensity-Modulated Arc Therapy (IMAT). Copyright © 2011 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  15. Independent calculation-based verification of IMRT plans using a 3D dose-calculation engine.

    PubMed

    Arumugam, Sankar; Xing, Aitang; Goozee, Gary; Holloway, Lois

    2013-01-01

    Independent monitor unit verification of intensity-modulated radiation therapy (IMRT) plans requires detailed 3-dimensional (3D) dose verification. The aim of this study was to investigate using a 3D dose engine in a second commercial treatment planning system (TPS) for this task, facilitated by in-house software. Our department has XiO and Pinnacle TPSs, both with IMRT planning capability and modeled for an Elekta-Synergy 6MV photon beam. These systems allow the transfer of computed tomography (CT) data and RT structures between them but do not allow IMRT plans to be transferred. To provide this connectivity, an in-house computer programme was developed to convert radiation therapy prescription (RTP) files as generated by many planning systems into either XiO or Pinnacle IMRT file formats. Utilization of the technique and software was assessed by transferring 14 IMRT plans from XiO and Pinnacle onto the other system and performing 3D dose verification. The accuracy of the conversion process was checked by comparing the 3D dose matrices and dose volume histograms (DVHs) of structures for the recalculated plan on the same system. The developed software successfully transferred IMRT plans generated by 1 planning system into the other. Comparison of planning target volume (TV) DVHs for the original and recalculated plans showed good agreement; a maximum difference of 2% in mean dose, - 2.5% in D95, and 2.9% in V95 was observed. Similarly, a DVH comparison of organs at risk showed a maximum difference of +7.7% between the original and recalculated plans for structures in both high- and medium-dose regions. However, for structures in low-dose regions (less than 15% of prescription dose) a difference in mean dose up to +21.1% was observed between XiO and Pinnacle calculations. A dose matrix comparison of original and recalculated plans in XiO and Pinnacle TPSs was performed using gamma analysis with 3%/3mm criteria. The mean and standard deviation of pixels passing gamma

  16. SU-E-T-126: Dosimetric Comparisons of VMAT, IMRT and 3DCRT for Locally Advanced Rectal Cancer with Simultaneous Integrated Boost

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zhao, J; Wang, J; Zhang, Z

    2014-06-01

    Purpose: The purpose of this study is to compare the dosimetric differences among volumetric modulated arc therapy (VMAT), fixed-field intensity modulated radiotherapy (IMRT) and three-dimensional conformal radiotherapy (3D-CRT) for the preoperative locally advanced rectal cancer (LARC). Methods: Ten LARC patients treated in our department using the simultaneous escalate strategy were retrospectively analyzed in this study. All patients had T3 with N+/− and were treated with IMRT. Two additional VMAT and 3DCRT plans were created for each patient. Both IMRT and VMAT had similar optimization objectives. The prescription was 50Gy to the PTV and 55Gy to the GTV. The target coveragemore » and organs at risk were compared for all the techniques.The paired, two-tailed Wilcoxcon signed-rank test was applied for statistical analysis. Results: IMRT and VMAT plans achieved comparable tumor response except for the conformality index (1.07 vs 1.19 and 1.08 vs 1.03 of IMRT vs VMAT for PTV-G and PTV-C respectively). Compared to VMAT, IMRT showed superior or similar dose sparing in the small bowel, bladder, femoral head. Both IMRT and VMAT had better organs at risk sparing and homogeneity index of PTV-G. Conclusion: All 3DCRT, IMRT and VMAT meet the prescript. The IMRT and VMAT provided comparable dosemitric parameters for target volume. IMRT shows better sparing for small bowel, bladder, femoral heads and normal tissue to 3DCRT and VMAT.« less

  17. Comparative Effectiveness Study of Patient-Reported Outcomes following Proton Therapy or IMRT for Prostate Cancer

    PubMed Central

    Hoppe, Bradford S.; Michalski, Jeff M.; Mendenhall, Nancy P.; Morris, Christopher G.; Henderson, Randal H.; Nichols, Romaine C.; Mendenhall, William M.; Williams, Christopher; Regan, Meredith M.; Chipman, Jonathan; Crociani, Catrina; Sandler, Howard M.; Sanda, Martin G.; Hamstra, Daniel A.

    2014-01-01

    Background Data continues to emerge on the relative merits of different treatment modalities for prostate cancer. The purpose of this study is to compare patient-reported quality-of-life outcomes (QOL) after proton therapy (PT) and intensity-modulated radiation therapy (IMRT) for prostate cancer. Methods A comparison was performed of prospectively collected QOL data using the expanded prostate cancer index (EPIC) questionnaire. QOL data was collected during the first 2 years following treatment for men treated with PT and IMRT. PT was delivered to 1,243 men at a single center to 76-82Gy. IMRT was delivered to 204 men included in the Prostate Cancer Quality Assurance Study (PROSTQA) in doses of 75.6-79.4Gy.The Wilcoxon rank sum test was used to compare EPIC outcomes by modality using baseline-adjusted scores at different time points. Individual questions were assessed by converting to binary outcomes and testing with generalized estimating equations. Results No differences in changes in summary scores for bowel, urinary incontinence, urinary irritative/obstructive, and sexual domains were seen between the two cohorts. However, more men treated with IMRT reported moderate/big problems with rectal urgency (p=0.02) and frequent bowel movements (p=0.05) than men treated with PT. Conclusions There were no differences in QOL summary scores between the IMRT and PT cohorts during early follow-up up to 2-years. Response to individual questions suggests possible differences in specific bowel symptoms between the two cohorts. These outcomes highlight the need for further comparative studies of PT and IMRT. PMID:24382757

  18. Reduced Feeding Tube Duration with IMRT for Head and Neck Cancer: A SEER-Medicare Analysis

    PubMed Central

    Beadle, Beth M.; Liao, Kai-Ping; Giordano, Sharon H.; Garden, Adam S.; Hutcheson, Katherine A.; Lai, Stephen Y.; Guadagnolo, B. Ashleigh

    2016-01-01

    Background Intensity-modulated radiation therapy (IMRT) is a technologically advanced and resource-intensive method of delivering radiation therapy (RT) used to minimize toxicity for patients with head and neck cancers (HNC). Dependence on feeding tubes is a significant marker of toxicity of RT. The goal of this analysis was to compare the placement and duration of feeding tube use for patients with HNC from 1999-2011. Methods The cohort, demographics, and cancer-related variables were determined using the linked Surveillance, Epidemiology, and End Results (SEER)-Medicare database and analyzed regarding treatment details using claims data. Results A total of 2993 patients were identified. With a median follow-up of 47 months, 54.4% of patients had a feeding tube placed. The median duration from feeding tube placement to removal was 277 days. On zero-inflated negative binomial regression, patients treated with IMRT and 3DRT (non-IMRT) had similar rates of feeding tube placement (odds ratio (OR) 1.10; p=.35); however, patients treated with 3DRT had the feeding tube in place 1.18 times longer than those treated with IMRT (p=.03). The difference was only seen amongst patients treated with definitive radiation; patients treated with surgery and adjuvant radiation had no statistically significant difference in placement or duration. Conclusions Patients with HNC treated with definitive IMRT had significantly shorter duration of feeding tubes in place than those treated with 3DRT. These data suggest that there may be significant quality of life benefits to IMRT with respect to long-term swallowing function for patients. PMID:27662641

  19. Intensity-modulated radiation therapy (IMRT) in the treatment of anal cancer: Toxicity and clinical outcome

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Milano, Michael T.; Jani, Ashesh B.; Farrey, Karl J.

    2005-10-01

    Purpose: To assess survival, local control, and toxicity of intensity modulated radiation therapy (IMRT) in squamous cell carcinoma of the anal canal. Methods and Materials: Seventeen patients were treated with nine-field IMRT plans. Thirteen received concurrent 5-fluorouracil and mitomycin C, whereas 1 patient received 5-fluorouracil alone. Seven patients were planned with three-dimensional anteroposterior/posterior-anterior (AP/PA) fields for dosimetric comparison to IMRT. Results: Compared with AP/PA, IMRT reduced the mean and threshold doses to small bowel, bladder, and genitalia. Treatment was well tolerated, with no Grade {>=}3 acute nonhematologic toxicity. There were no treatment breaks attributable to gastrointestinal or skin toxicity. Ofmore » patients who received mitomycin C, 38% experienced Grade 4 hematologic toxicity. IMRT did not afford bone marrow sparing, possibly resulting from the clinical decision to prescribe 45 Gy to the whole pelvis in most patients, vs. the Radiation Therapy Oncology Group-recommended 30.6 Gy whole pelvic dose. Three of 17 patients, who did not achieve a complete response, proceeded to an abdominoperineal resection and colostomy. At a median follow-up of 20.3 months, there were no other local failures. Two-year overall survival, disease-free survival, and colostomy-free survival are: 91%, 65%, and 82% respectively. Conclusions: In this hypothesis-generating analysis, the acute toxicity and clinical outcome with IMRT in the treatment of anal cancer is encouraging. Compared with historical controls, local control is not compromised despite efforts to increase conformality and reduce normal structure dose.« less

  20. Total dural irradiation: RapidArc versus static-field IMRT: A case study

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kelly, Paul J., E-mail: paulj.kelly@hse.ie; Mannarino, Edward; Lewis, John Henry

    2012-07-01

    The purpose of this study was to compare conventional fixed-gantry angle intensity-modulated radiation therapy (IMRT) with RapidArc for total dural irradiation. We also hypothesize that target volume-individualized collimator angles may produce substantial normal tissue sparing when planning with RapidArc. Five-, 7-, and 9-field fixed-gantry angle sliding-window IMRT plans were generated for comparison with RapidArc plans. Optimization and normal tissue constraints were constant for all plans. All plans were normalized so that 95% of the planning target volume (PTV) received at least 100% of the dose. RapidArc was delivered using 350 Degree-Sign clockwise and counterclockwise arcs. Conventional collimator angles of 45more » Degree-Sign and 315 Degree-Sign were compared with 90 Degree-Sign on both arcs. Dose prescription was 59.4 Gy in 33 fractions. PTV metrics used for comparison were coverage, V{sub 107}%, D1%, conformality index (CI{sub 95}%), and heterogeneity index (D{sub 5}%-D{sub 95}%). Brain dose, the main challenge of this case, was compared using D{sub 1}%, Dmean, and V{sub 5} Gy. Dose to optic chiasm, optic nerves, globes, and lenses was also compared. The use of unconventional collimator angles (90 Degree-Sign on both arcs) substantially reduced dose to normal brain. All plans achieved acceptable target coverage. Homogeneity was similar for RapidArc and 9-field IMRT plans. However, heterogeneity increased with decreasing number of IMRT fields, resulting in unacceptable hotspots within the brain. Conformality was marginally better with RapidArc relative to IMRT. Low dose to brain, as indicated by V5Gy, was comparable in all plans. Doses to organs at risk (OARs) showed no clinically meaningful differences. The number of monitor units was lower and delivery time was reduced with RapidArc. The case-individualized RapidArc plan compared favorably with the 9-field conventional IMRT plan. In view of lower monitor unit requirements and shorter delivery time

  1. Microionization chamber for reference dosimetry in IMRT verification: clinical implications on OAR dosimetric errors

    NASA Astrophysics Data System (ADS)

    Sánchez-Doblado, Francisco; Capote, Roberto; Leal, Antonio; Roselló, Joan V.; Lagares, Juan I.; Arráns, Rafael; Hartmann, Günther H.

    2005-03-01

    Intensity modulated radiotherapy (IMRT) has become a treatment of choice in many oncological institutions. Small fields or beamlets with sizes of 1 to 5 cm2 are now routinely used in IMRT delivery. Therefore small ionization chambers (IC) with sensitive volumes <=0.1 cm3are generally used for dose verification of an IMRT treatment. The measurement conditions during verification may be quite different from reference conditions normally encountered in clinical beam calibration, so dosimetry of these narrow photon beams pertains to the so-called non-reference conditions for beam calibration. This work aims at estimating the error made when measuring the organ at risk's (OAR) absolute dose by a micro ion chamber (μIC) in a typical IMRT treatment. The dose error comes from the assumption that the dosimetric parameters determining the absolute dose are the same as for the reference conditions. We have selected two clinical cases, treated by IMRT, for our dose error evaluations. Detailed geometrical simulation of the μIC and the dose verification set-up was performed. The Monte Carlo (MC) simulation allows us to calculate the dose measured by the chamber as a dose averaged over the air cavity within the ion-chamber active volume (Dair). The absorbed dose to water (Dwater) is derived as the dose deposited inside the same volume, in the same geometrical position, filled and surrounded by water in the absence of the ion chamber. Therefore, the Dwater/Dair dose ratio is the MC estimator of the total correction factor needed to convert the absorbed dose in air into the absorbed dose in water. The dose ratio was calculated for the μIC located at the isocentre within the OARs for both clinical cases. The clinical impact of the calculated dose error was found to be negligible for the studied IMRT treatments.

  2. WE-D-BRA-06: IMRT QA with ArcCHECK: The MD Anderson Experience

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Aristophanous, M; Suh, Y; Chi, P

    Purpose: The objective of this project was to report our initial IMRT QA results and experience with the SunNuclear ArcCHECK. Methods: Three thousand one-hundred and sixteen cases were treated with IMRT or VMAT at our institution between October 2013 and September 2014. All IMRT/VMAT treatment plans underwent Quality Assurance (QA) using ArcCHECK prior to therapy. For clinical evaluation, a Gamma analysis is performed following QA delivery using the SNC Patient software (Sun Nuclear Corp) at the 3%/3mm level. QA Gamma pass rates were analyzed based on categories of treatment site, technique, and type of MLCs. Our current clinical threshold formore » passing a QA (Tclin) is set at a Gamma pass rate greater than 90%. We recorded the percent of failures for each category, as well as the Gamma pass rate threshold that would Result in 95% of QAs to pass (T95). Results: Using Tclin a failure rate of 5.9% over all QAs was observed. The highest failure rate was observed for gynecological (22%) and the lowest for CNS (0.9%) treatments. T95 was 91% over all QAs and ranged from 73% (gynecological) to 96.5% (CNS) for individual treatments sites. T95 was lower for IMRT and non-HD (high definition) MLCs at 88.5% and 94.5%, respectively, compared to 92.4% and 97.1% for VMAT and HD MLC treatments, respectively. There was a statistically significant difference between the passing rates for IMRT vs. VMAT and for HD MLCs vs. non-HD MLCs (p-values << 0.01). Gynecological, IMRT, and HD MLC treatments typically include more plans with larger field sizes. Conclusion: On average, Tclin with ArcCHECK was consistent with T95, as well as the 90% action level reported in TG-119. However, significant variations between the examined categories suggest a link between field size and QA passing rates and may warrant field size-specific passing rate thresholds.« less

  3. Dose Volume Histogram (DVH) Analysis in Intensity Modulation Radiation Therapy (IMRT) Treatments for Prostate Cancers

    NASA Astrophysics Data System (ADS)

    Pyakuryal, Anil

    2009-05-01

    Studies have shown that as many as 8 out of 10 men had prostate cancer by age 80.Prostate cancer begins with small changes (prostatic intraepithelial neoplasia(PIN)) in size and shape of prostate gland cells,known as prostate adenocarcinoma.With advent in technology, prostate cancer has been the most widely used application of IMRT with the longest follow-up periods.Prostate cancer fits the ideal target criteria for IMRT of adjacent sensitive dose-limiting tissue (rectal, bladder).A retrospective study was performed on 10 prostate cancer patients treated with radiation to a limited pelvic field with a standard 4 field arrangements at dose 45 Gy, and an IMRT boost field to a total isocenter dose of 75 Gy.Plans were simulated for 4 field and the supplementary IMRT treatments with proposed dose delivery at 1.5 Gy/fraction in BID basis.An automated DVH analysis software, HART (S. Jang et al., 2008,Med Phys 35,p.2812)was used to perform DVH assessments in IMRT plans.A statistical analysis of dose coverage at targets in prostate gland and neighboring critical organs,and the plan indices(homogeneity, conformality etc) evaluations were also performed using HART extracted DVH statistics.Analyzed results showed a better correlation with the proposed outcomes (TCP, NTCP) of the treatments.

  4. SU-G-TeP4-02: A Method for Evaluating the Direct Impact of Failed IMRT QAs On Patient Dose

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Geneser, S; Butkus, M

    Purpose: We developed a method to calculate patient doses corresponding to IMRT QA measurements in order to determine and assess the actual dose delivered for plans with failed (or borderline) IMRT QA. This work demonstrates the feasibility of automatically computing delivered patient dose from portal dosimetry measurements in the Varian TPS system, which would provide a valuable and clinically viable IMRT QA tool for physicists and physicians. Methods: IMRT QA fluences were measured using portal dosimetry, processed using in-house matlab software, and imported back into Eclipse to calculate dose on the planning CT. To validate the proposed workflow, the Eclipsemore » calculated portal dose for a 5-field sliding window prostate boost plan was processed as described above. The resulting dose was compared to the planned dose and found to be within 0.5 Gy. Two IMRT QA results for the prostate boost plan (one that failed and one that passed) were processed and the resulting patient doses were evaluated. Results: The max dose difference between IMRT QA #1 and the original planned and approved dose is 4.5 Gy, while the difference between the planned and IMRT QA #2 dose is 4.0 Gy. The inferior portion of the PTV is slightly underdosed in both plans, and the superior portion is slightly overdosed. The patient dose resulting from IMRT QA #1 and #2 differs by only 0.5 Gy. With this new information, it may be argued that the evaluated plan alteration to obtain passing gamma analysis produced clinically irrelevant differences. Conclusion: Evaluation of the delivered QA dose on the planning CT provides valuable information about the clinical relevance of failed or borderline IMRT QAs. This particular workflow demonstrates the feasibility of pushing the measured IMRT QA portal dosimetry results directly back onto the patient planning CT within the Varian system.« less

  5. Intensity modulated radiation therapy (IMRT): differences in target volumes and improvement in clinically relevant doses to small bowel in rectal carcinoma.

    PubMed

    Mok, Henry; Crane, Christopher H; Palmer, Matthew B; Briere, Tina M; Beddar, Sam; Delclos, Marc E; Krishnan, Sunil; Das, Prajnan

    2011-06-08

    A strong dose-volume relationship exists between the amount of small bowel receiving low- to intermediate-doses of radiation and the rates of acute, severe gastrointestinal toxicity, principally diarrhea. There is considerable interest in the application of highly conformal treatment approaches, such as intensity-modulated radiation therapy (IMRT), to reduce dose to adjacent organs-at-risk in the treatment of carcinoma of the rectum. Therefore, we performed a comprehensive dosimetric evaluation of IMRT compared to 3-dimensional conformal radiation therapy (3DCRT) in standard, preoperative treatment for rectal cancer. Using RTOG consensus anorectal contouring guidelines, treatment volumes were generated for ten patients treated preoperatively at our institution for rectal carcinoma, with IMRT plans compared to plans derived from classic anatomic landmarks, as well as 3DCRT plans treating the RTOG consensus volume. The patients were all T3, were node-negative (N = 1) or node-positive (N = 9), and were planned to a total dose of 45-Gy. Pairwise comparisons were made between IMRT and 3DCRT plans with respect to dose-volume histogram parameters. IMRT plans had superior PTV coverage, dose homogeneity, and conformality in treatment of the gross disease and at-risk nodal volume, in comparison to 3DCRT. Additionally, in comparison to the 3DCRT plans, IMRT achieved a concomitant reduction in doses to the bowel (small bowel mean dose: 18.6-Gy IMRT versus 25.2-Gy 3DCRT; p = 0.005), bladder (V40Gy: 56.8% IMRT versus 75.4% 3DCRT; p = 0.005), pelvic bones (V40Gy: 47.0% IMRT versus 56.9% 3DCRT; p = 0.005), and femoral heads (V40Gy: 3.4% IMRT versus 9.1% 3DCRT; p = 0.005), with an improvement in absolute volumes of small bowel receiving dose levels known to induce clinically-relevant acute toxicity (small bowel V15Gy: 138-cc IMRT versus 157-cc 3DCRT; p = 0.005). We found that the IMRT treatment volumes were typically larger than that covered by classic bony landmark-derived fields

  6. Quality correction factors of composite IMRT beam deliveries: Theoretical considerations

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Bouchard, Hugo

    2012-11-15

    Purpose: In the scope of intensity modulated radiation therapy (IMRT) dosimetry using ionization chambers, quality correction factors of plan-class-specific reference (PCSR) fields are theoretically investigated. The symmetry of the problem is studied to provide recommendable criteria for composite beam deliveries where correction factors are minimal and also to establish a theoretical limit for PCSR delivery k{sub Q} factors. Methods: The concept of virtual symmetric collapsed (VSC) beam, being associated to a given modulated composite delivery, is defined in the scope of this investigation. Under symmetrical measurement conditions, any composite delivery has the property of having a k{sub Q} factor identicalmore » to its associated VSC beam. Using this concept of VSC, a fundamental property of IMRT k{sub Q} factors is demonstrated in the form of a theorem. The sensitivity to the conditions required by the theorem is thoroughly examined. Results: The theorem states that if a composite modulated beam delivery produces a uniform dose distribution in a volume V{sub cyl} which is symmetric with the cylindrical delivery and all beams fulfills two conditions in V{sub cyl}: (1) the dose modulation function is unchanged along the beam axis, and (2) the dose gradient in the beam direction is constant for a given lateral position; then its associated VSC beam produces no lateral dose gradient in V{sub cyl}, no matter what beam modulation or gantry angles are being used. The examination of the conditions required by the theorem lead to the following results. The effect of the depth-dose gradient not being perfectly constant with depth on the VSC beam lateral dose gradient is found negligible. The effect of the dose modulation function being degraded with depth on the VSC beam lateral dose gradient is found to be only related to scatter and beam hardening, as the theorem holds also for diverging beams. Conclusions: The use of the symmetry of the problem in the present paper

  7. Comparison of dose accuracy between 2D array detectors and Epid for IMRT of nasopharynx cancer

    NASA Astrophysics Data System (ADS)

    Altiparmak, Duygu; Coban, Yasin; Merih, Adil; Avci, Gulhan Guler; Yigitoglu, Ibrahim

    2017-02-01

    The aim of this study is to perform the dosimetric controls of nasopharynx cancer patient's intensity modulated radiation therapy (IMRT) treatment plans that generated by treatment planing system (TPS) with using two different equipments and also to make comparison in terms of their reliability and practicability. This study has been performed at Radiation Oncology Department, Medicine Faculty in Gaziosmanpasa University by using the VARIAN CLINAC DHX linear accelerator which is operated in the range of 6 MV. Selected 10 nasopharynx patients planned in TPS (Eclipce V13.0) and approved for treatment by medical physicists and radiation oncologists. These plans recalculated on EPID and mapcheck which are 2D dosimetric equipments to obtain dose maps. To compare these two dosimetric equipments gamma analysis method has been preferred. Achieved data is presented and discussed.

  8. Carcinoma of the anal canal: Intensity modulated radiation therapy (IMRT) versus three-dimensional conformal radiation therapy (3DCRT).

    PubMed

    Sale, Charlotte; Moloney, Phillip; Mathlum, Maitham

    2013-12-01

    Patients with anal canal carcinoma treated with standard conformal radiotherapy frequently experience severe acute and late toxicity reactions to the treatment area. Roohipour et al. (Dis Colon Rectum 2008; 51: 147-53) stated a patient's tolerance of chemoradiation to be an important prediction of treatment success. A new intensity modulated radiation therapy (IMRT) technique for anal carcinoma cases has been developed at the Andrew Love Cancer Centre aimed at reducing radiation to surrounding healthy tissue. A same-subject repeated measures design was used for this study, where five anal carcinoma cases at the Andrew Love Cancer Centre were selected. Conformal and IMRT plans were generated and dosimetric evaluations were performed. Each plan was prescribed a total of 54 Gray (Gy) over a course of 30 fractions to the primary site. The IMRT plans resulted in improved dosimetry to the planning target volume (PTV) and reduction in radiation to the critical structures (bladder, external genitalia and femoral heads). Statistically there was no difference between the IMRT and conformal plans in the dose to the small and large bowel; however, the bowel IMRT dose-volume histogram (DVH) doses were consistently lower. The IMRT plans were superior to the conformal plans with improved dose conformity and reduced radiation to the surrounding healthy tissue. Anecdotally it was found that patients tolerated the IMRT treatment better than the three-dimensional (3D) conformal radiation therapy. This study describes and compares the planning techniques.

  9. Carcinoma of the anal canal: Intensity modulated radiation therapy (IMRT) versus three-dimensional conformal radiation therapy (3DCRT)

    PubMed Central

    Sale, Charlotte; Moloney, Phillip; Mathlum, Maitham

    2013-01-01

    Introduction Patients with anal canal carcinoma treated with standard conformal radiotherapy frequently experience severe acute and late toxicity reactions to the treatment area. Roohipour et al. (Dis Colon Rectum 2008; 51: 147–53) stated a patient's tolerance of chemoradiation to be an important prediction of treatment success. A new intensity modulated radiation therapy (IMRT) technique for anal carcinoma cases has been developed at the Andrew Love Cancer Centre aimed at reducing radiation to surrounding healthy tissue. Methods A same-subject repeated measures design was used for this study, where five anal carcinoma cases at the Andrew Love Cancer Centre were selected. Conformal and IMRT plans were generated and dosimetric evaluations were performed. Each plan was prescribed a total of 54 Gray (Gy) over a course of 30 fractions to the primary site. Results The IMRT plans resulted in improved dosimetry to the planning target volume (PTV) and reduction in radiation to the critical structures (bladder, external genitalia and femoral heads). Statistically there was no difference between the IMRT and conformal plans in the dose to the small and large bowel; however, the bowel IMRT dose–volume histogram (DVH) doses were consistently lower. Conclusion The IMRT plans were superior to the conformal plans with improved dose conformity and reduced radiation to the surrounding healthy tissue. Anecdotally it was found that patients tolerated the IMRT treatment better than the three-dimensional (3D) conformal radiation therapy. This study describes and compares the planning techniques. PMID:26229623

  10. Inverse-optimized 3D conformal planning: Minimizing complexity while achieving equivalence with beamlet IMRT in multiple clinical sites

    PubMed Central

    Fraass, Benedick A.; Steers, Jennifer M.; Matuszak, Martha M.; McShan, Daniel L.

    2012-01-01

    Purpose: Inverse planned intensity modulated radiation therapy (IMRT) has helped many centers implement highly conformal treatment planning with beamlet-based techniques. The many comparisons between IMRT and 3D conformal (3DCRT) plans, however, have been limited because most 3DCRT plans are forward-planned while IMRT plans utilize inverse planning, meaning both optimization and delivery techniques are different. This work avoids that problem by comparing 3D plans generated with a unique inverse planning method for 3DCRT called inverse-optimized 3D (IO-3D) conformal planning. Since IO-3D and the beamlet IMRT to which it is compared use the same optimization techniques, cost functions, and plan evaluation tools, direct comparisons between IMRT and simple, optimized IO-3D plans are possible. Though IO-3D has some similarity to direct aperture optimization (DAO), since it directly optimizes the apertures used, IO-3D is specifically designed for 3DCRT fields (i.e., 1–2 apertures per beam) rather than starting with IMRT-like modulation and then optimizing aperture shapes. The two algorithms are very different in design, implementation, and use. The goals of this work include using IO-3D to evaluate how close simple but optimized IO-3D plans come to nonconstrained beamlet IMRT, showing that optimization, rather than modulation, may be the most important aspect of IMRT (for some sites). Methods: The IO-3D dose calculation and optimization functionality is integrated in the in-house 3D planning/optimization system. New features include random point dose calculation distributions, costlet and cost function capabilities, fast dose volume histogram (DVH) and plan evaluation tools, optimization search strategies designed for IO-3D, and an improved, reimplemented edge/octree calculation algorithm. The IO-3D optimization, in distinction to DAO, is designed to optimize 3D conformal plans (one to two segments per beam) and optimizes MLC segment shapes and weights with various

  11. Comparison of 3DCRT,VMAT and IMRT techniques in metastatic vertebra radiotherapy: A phantom Study

    NASA Astrophysics Data System (ADS)

    Gedik, Sonay; Tunc, Sema; Kahraman, Arda; Kahraman Cetintas, Sibel; Kurt, Meral

    2017-09-01

    Vertebra metastases can be seen during the prognosis of cancer patients. Treatment ways of the metastasis are radiotherapy, chemotherapy and surgery. Three-dimensional conformal therapy (3D-CRT) is widely used in the treatment of vertebra metastases. Also, Intensity Modulated Radiotherapy (IMRT) and Volumetric Arc Therapy (VMAT) are used too. The aim of this study is to examine the advantages and disadvantages of the different radiotherapy techniques. In the aspect of this goal, it is studied with a randophantom in Uludag University Medicine Faculty, Radiation Oncology Department. By using a computerized tomography image of the phantom, one 3DCRT plan, two VMAT and three IMRT plans for servical vertebra and three different 3DCRT plans, two VMAT and two IMRT plans for lomber vertebra are calculated. To calculate 3DCRT plans, CMS XiO Treatment System is used and to calculate VMAT and IMRT plans Monaco Treatment Planning System is used in the department. The study concludes with the dosimetric comparison of the treatment plans in the spect of critical organ doses, homogeneity and conformity index. As a result of this study, all critical organ doses are suitable for QUANTEC Dose Limit Report and critical organ doses depend on the techniques which used in radiotherapy. According to homogeneity and conformity indices, VMAT and IMRT plans are better than one in 3DCRT plans in servical and lomber vertebra radiotherapy plans.

  12. Treatment plan comparison between helical tomotherapy and MLC-based IMRT using radiobiological measures

    NASA Astrophysics Data System (ADS)

    Mavroidis, Panayiotis; Costa Ferreira, Brigida; Shi, Chengyu; Lind, Bengt K.; Papanikolaou, Nikos

    2007-07-01

    The rapid implementation of advanced treatment planning and delivery technologies for radiation therapy has brought new challenges in evaluating the most effective treatment modality. Intensity-modulated radiotherapy (IMRT) using multi-leaf collimators (MLC) and helical tomotherapy (HT) are becoming popular modes of treatment delivery and their application and effectiveness continues to be investigated. Presently, there are several treatment planning systems (TPS) that can generate and optimize IMRT plans based on user-defined objective functions for the internal target volume (ITV) and organs at risk (OAR). However, the radiobiological parameters of the different tumours and normal tissues are typically not taken into account during dose prescription and optimization of a treatment plan or during plan evaluation. The suitability of a treatment plan is typically decided based on dosimetric criteria such as dose-volume histograms (DVH), maximum, minimum, mean and standard deviation of the dose distribution. For a more comprehensive treatment plan evaluation, the biologically effective uniform dose ({\\bar{\\bar{D}}}) is applied together with the complication-free tumour control probability (P+). Its utilization is demonstrated using three clinical cases that were planned with two different forms of IMRT. In this study, three different cancer types at different anatomical sites were investigated: head and neck, lung and prostate cancers. For each cancer type, a linac MLC-based step-and-shoot IMRT plan and a HT plan were developed. The MLC-based IMRT treatment plans were developed on the Philips treatment-planning platform, using the Pinnacle 7.6 software release. For the tomotherapy HiArt plans, the dedicated tomotherapy treatment planning station was used, running version 2.1.2. By using {\\bar{\\bar{D}}} as the common prescription point of the treatment plans and plotting the tissue response probabilities versus {\\bar{\\bar{D}}} for a range of prescription doses

  13. Long-term disease control and toxicity outcomes following surgery and intensity modulated radiation therapy (IMRT) in pediatric craniopharyngioma.

    PubMed

    Greenfield, Brad J; Okcu, Mehmet F; Baxter, Patricia A; Chintagumpala, Murali; Teh, Bin S; Dauser, Robert C; Su, Jack; Desai, Snehal S; Paulino, Arnold C

    2015-02-01

    To report long-term progression-free survival (PFS) and late-toxicity outcomes in pediatric craniopharyngioma patients treated with IMRT. Twenty-four children were treated with IMRT to a median dose of 50.4Gy (range, 49.8-54Gy). The clinical target volume (CTV) was the gross tumor volume (GTV) with a 1cm margin. The planning target volume (PTV) was the CTV with a 3-5mm margin. Median follow-up was 107.3months. The 5- and 10-year PFS rates were 65.8% and 60.7%. The 5- and 10-year cystic PFS rates were 70.2% and 65.2% while the 5- and 10-year solid PFS were the same at 90.7%. Endocrinopathy was seen in 42% at initial diagnosis and in 74% after surgical intervention, prior to IMRT. Hypothalamic dysfunction and visual deficits were associated with increasing PTV and number of surgical interventions. IMRT is a viable treatment option for pediatric craniopharyngioma. Despite the use of IMRT, majority of the craniopharyngioma patients experienced long-term toxicity, many of which present prior to radiotherapy. Limitations of retrospective analyses on small patient cohort elicit the need for a prospective multi-institutional study to determine the absolute benefit of IMRT in pediatric craniopharyngioma. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  14. Conformal radiotherapy, reduced boost volume, hyperfractionated radiotherapy, and online quality control in standard-risk medulloblastoma without chemotherapy: Results of the French M-SFOP 98 protocol

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Carrie, Christian; Muracciole, Xavier; Gomez, Frederic

    2005-11-01

    Purpose: Between December 1998 and October 2001, patients <19 years old were treated for standard-risk medulloblastoma according to the Medulloblastome-Societe Francaise d'Oncologie Pediatrique 1998 (M-SFOP 98) protocol. Patients received hyperfractionated radiotherapy (36 Gy in 36 fractions) to the craniospinal axis, a boost with conformal therapy restricted to the tumor bed (to a total dose of 68 Gy in 68 fractions), and no chemotherapy. Records of craniospinal irradiation were reviewed before treatment start. Results: A total of 48 patients were considered assessable. With a median follow-up of 45.7 months, the overall survival and progression-free survival rate at 3 years was 89%more » and 81%, respectively. Fourteen major deviations were detected and eight were corrected. No relapses occurred in the frontal region and none occurred in the posterior fossa outside the boost volume. Nine patients were available for volume calculation without reduction of the volume irradiated. We observed a reduction in the subtentorial volume irradiated to >60 Gy, but a slight increase in the volume irradiated to 40 Gy. No decrease in intelligence was observed in the 22 children tested during the first 2 years. Conclusion: This hyperfractionated radiotherapy protocol with a reduced boost volume and without chemotherapy was not associated with early relapses in children. Moreover, intellectual function seemed to be preserved. These results are promising.« less

  15. SU-F-T-295: MLCs Performance and Patient-Specific IMRT QA Using Log File Analysis

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Osman, A; American University of Biuret Medical Center, Biuret; Maalej, N

    2016-06-15

    Purpose: To analyze the performance of the multi-leaf collimators (MLCs) from the log files recorded during the intensity modulated radiotherapy (IMRT) treatment and to construct the relative fluence maps and do the gamma analysis to compare the planned and executed MLCs movement. Methods: We developed a program to extract and analyze the data from dynamic log files (dynalog files) generated from sliding window IMRT delivery treatments. The program extracts the planned and executed (actual or delivered) MLCs movement, calculates and compares the relative planned and executed fluences. The fluence maps were used to perform the gamma analysis (with 3% dosemore » difference and 3 mm distance to agreement) for 3 IMR patients. We compared our gamma analysis results with those obtained from portal dose image prediction (PDIP) algorithm performed using the EPID. Results: For 3 different IMRT patient treatments, the maximum difference between the planned and the executed MCLs positions was 1.2 mm. The gamma analysis results of the planned and delivered fluences were in good agreement with the gamma analysis from portal dosimetry. The maximum difference for number of pixels passing the gamma criteria (3%/3mm) was 0.19% with respect to portal dosimetry results. Conclusion: MLC log files can be used to verify the performance of the MLCs. Patientspecific IMRT QA based on MLC movement log files gives similar results to EPID dosimetry results. This promising method for patient-specific IMRT QA is fast, does not require dose measurements in a phantom, can be done before the treatment and for every fraction, and significantly reduces the IMRT workload. The author would like to thank King Fahd University of petroleum and Minerals for the support.« less

  16. MO-G-BRE-02: A Survey of IMRT QA Practices for More Than 800 Institutions

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Pulliam, K; Kerns, J; Howell, R

    Purpose: A wide range of techniques and measurement devices are employed for IMRT QA, causing a large variation of accepted action limits and potential follow up for failing plans. Such procedures are not well established or accepted in the medical physics community. To achieve the goal of proving insight into current IMRT QA practices, we created an electronic IMRT QA survey. The survey was open to a variety of the most common QA devices and assessed the type of comparison to measurement, action limits, delivery methods, and clinical action for failing QA plans. Methods: We conducted an online survey throughmore » the Radiological Physics Center's (RPC) annual survey with the goal of ascertaining elements of routine patient-specific IMRT QA. A total of 874 institutions responded to the survey. The questions ranged from asking for action limits, dosimeter type(s) used, delivery techniques, and actions taken when a plan fails IMRT QA. Results: The most common (52%) planar gamma criteria was 3%/3 mm with a 95% of pixels passing criteria. The most common QA device were diode arrays (48%). The most common first response to a plan failing QA was to re-measure at the same point the point dose (89%), second was to re-measure at a new point (13%), and third was to analyze the plan in relative instead of absolute mode (10%) (Does not add to 100% as not all institutions placed a response for each QA follow-up option). Some institutions, however, claimed that they had never observed a plan failure. Conclusion: The survey provided insights into the way the community currently performs IMRT QA. This information will help in the push to standardize action limits among dosimeters.« less

  17. Investigation of effective decision criteria for multiobjective optimization in IMRT.

    PubMed

    Holdsworth, Clay; Stewart, Robert D; Kim, Minsun; Liao, Jay; Phillips, Mark H

    2011-06-01

    To investigate how using different sets of decision criteria impacts the quality of intensity modulated radiation therapy (IMRT) plans obtained by multiobjective optimization. A multiobjective optimization evolutionary algorithm (MOEA) was used to produce sets of IMRT plans. The MOEA consisted of two interacting algorithms: (i) a deterministic inverse planning optimization of beamlet intensities that minimizes a weighted sum of quadratic penalty objectives to generate IMRT plans and (ii) an evolutionary algorithm that selects the superior IMRT plans using decision criteria and uses those plans to determine the new weights and penalty objectives of each new plan. Plans resulting from the deterministic algorithm were evaluated by the evolutionary algorithm using a set of decision criteria for both targets and organs at risk (OARs). Decision criteria used included variation in the target dose distribution, mean dose, maximum dose, generalized equivalent uniform dose (gEUD), an equivalent uniform dose (EUD(alpha,beta) formula derived from the linear-quadratic survival model, and points on dose volume histograms (DVHs). In order to quantatively compare results from trials using different decision criteria, a neutral set of comparison metrics was used. For each set of decision criteria investigated, IMRT plans were calculated for four different cases: two simple prostate cases, one complex prostate Case, and one complex head and neck Case. When smaller numbers of decision criteria, more descriptive decision criteria, or less anti-correlated decision criteria were used to characterize plan quality during multiobjective optimization, dose to OARs and target dose variation were reduced in the final population of plans. Mean OAR dose and gEUD (a = 4) decision criteria were comparable. Using maximum dose decision criteria for OARs near targets resulted in inferior populations that focused solely on low target variance at the expense of high OAR dose. Target dose range, (D

  18. SU-E-T-643: Pure Alanine Dosimeter for Verification Dosimetry in IMRT

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Al-Karmi, Anan M.; Zraiqat, Fadi

    Purpose: The objective of this study was evaluation of accuracy of pure alanine dosimeters measuring intensity-modulated radiation therapy (IMRT) dose distributions in a thorax phantom. Methods: Alanine dosimeters were prepared in the form of 110 mg pure L-α-alanine powder filled into clear tissue-equivalent polymethylmethacrylate (PMMA) plastic tubes with the dimensions 25 mm length, 3 mm inner diameter, and 1 mm wall thickness. A dose-response calibration curve was established for the alanine by placing the dosimeters at 1.5 cm depth in a 30×30×30 cm{sup 3} solid water phantom and then irradiating on a linac with 6 MV photon beam at 10×10more » cm{sup 2} field size to doses ranging from 1 to 5 Gy. Electron paramagnetic resonance (EPR) spectroscopy was used to determine the absorbed dose in alanine. An IMRT treatment plan was designed for a commercial heterogeneous CIRS thorax phantom and the dose values were calculated at three different points located in tissue, lung, and bone equivalent materials. A set of dose measurements was carried out to compare measured and calculated dose values by placing the alanine dosimeters at those selected locations inside the thorax phantom and delivering the IMRT to the phantom. Results: The alanine dose measurements and the IMRT plan dose calculations were found to be in agreement within ±2%. Specifically, the deviations were −0.5%, 1.3%, and −1.7% for tissue, lung, and bone; respectively. The slightly large deviations observed for lung and bone may be attributed to tissue inhomogeneity, steep dose gradients in these regions, and uncontrollable changes in spectrometer conditions. Conclusion: The results described herein confirmed that pure alanine dosimeter was suitable for in-phantom dosimetry of IMRT beams because of its high sensitivity and acceptable accuracy. This makes the dosimeter a promising option for quality control of the therapeutic beams, complementing the commonly used ionization chambers, TLDs, and

  19. FusionArc optimization: a hybrid volumetric modulated arc therapy (VMAT) and intensity modulated radiation therapy (IMRT) planning strategy.

    PubMed

    Matuszak, Martha M; Steers, Jennifer M; Long, Troy; McShan, Daniel L; Fraass, Benedick A; Romeijn, H Edwin; Ten Haken, Randall K

    2013-07-01

    To introduce a hybrid volumetric modulated arc therapy/intensity modulated radiation therapy (VMAT/IMRT) optimization strategy called FusionArc that combines the delivery efficiency of single-arc VMAT with the potentially desirable intensity modulation possible with IMRT. A beamlet-based inverse planning system was enhanced to combine the advantages of VMAT and IMRT into one comprehensive technique. In the hybrid strategy, baseline single-arc VMAT plans are optimized and then the current cost function gradients with respect to the beamlets are used to define a metric for predicting which beam angles would benefit from further intensity modulation. Beams with the highest metric values (called the gradient factor) are converted from VMAT apertures to IMRT fluence, and the optimization proceeds with the mixed variable set until convergence or until additional beams are selected for conversion. One phantom and two clinical cases were used to validate the gradient factor and characterize the FusionArc strategy. Comparisons were made between standard IMRT, single-arc VMAT, and FusionArc plans with one to five IMRT∕hybrid beams. The gradient factor was found to be highly predictive of the VMAT angles that would benefit plan quality the most from beam modulation. Over the three cases studied, a FusionArc plan with three converted beams achieved superior dosimetric quality with reductions in final cost ranging from 26.4% to 48.1% compared to single-arc VMAT. Additionally, the three beam FusionArc plans required 22.4%-43.7% fewer MU∕Gy than a seven beam IMRT plan. While the FusionArc plans with five converted beams offer larger reductions in final cost--32.9%-55.2% compared to single-arc VMAT--the decrease in MU∕Gy compared to IMRT was noticeably smaller at 12.2%-18.5%, when compared to IMRT. A hybrid VMAT∕IMRT strategy was implemented to find a high quality compromise between gantry-angle and intensity-based degrees of freedom. This optimization method will allow

  20. The effects of small field dosimetry on the biological models used in evaluating IMRT dose distributions

    NASA Astrophysics Data System (ADS)

    Cardarelli, Gene A.

    The primary goal in radiation oncology is to deliver lethal radiation doses to tumors, while minimizing dose to normal tissue. IMRT has the capability to increase the dose to the targets and decrease the dose to normal tissue, increasing local control, decrease toxicity and allow for effective dose escalation. This advanced technology does present complex dose distributions that are not easily verified. Furthermore, the dose inhomogeneity caused by non-uniform dose distributions seen in IMRT treatments has caused the development of biological models attempting to characterize the dose-volume effect in the response of organized tissues to radiation. Dosimetry of small fields can be quite challenging when measuring dose distributions for high-energy X-ray beams used in IMRT. The proper modeling of these small field distributions is essential in reproducing accurate dose for IMRT. This evaluation was conducted to quantify the effects of small field dosimetry on IMRT plan dose distributions and the effects on four biological model parameters. The four biological models evaluated were: (1) the generalized Equivalent Uniform Dose (gEUD), (2) the Tumor Control Probability (TCP), (3) the Normal Tissue Complication Probability (NTCP) and (4) the Probability of uncomplicated Tumor Control (P+). These models are used to estimate local control, survival, complications and uncomplicated tumor control. This investigation compares three distinct small field dose algorithms. Dose algorithms were created using film, small ion chamber, and a combination of ion chamber measurements and small field fitting parameters. Due to the nature of uncertainties in small field dosimetry and the dependence of biological models on dose volume information, this examination quantifies the effects of small field dosimetry techniques on radiobiological models and recommends pathways to reduce the errors in using these models to evaluate IMRT dose distributions. This study demonstrates the importance

  1. TH-AB-BRA-07: PENELOPE-Based GPU-Accelerated Dose Calculation System Applied to MRI-Guided Radiation Therapy

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wang, Y; Mazur, T; Green, O

    Purpose: The clinical commissioning of IMRT subject to a magnetic field is challenging. The purpose of this work is to develop a GPU-accelerated Monte Carlo dose calculation platform based on PENELOPE and then use the platform to validate a vendor-provided MRIdian head model toward quality assurance of clinical IMRT treatment plans subject to a 0.35 T magnetic field. Methods: We first translated PENELOPE from FORTRAN to C++ and validated that the translation produced equivalent results. Then we adapted the C++ code to CUDA in a workflow optimized for GPU architecture. We expanded upon the original code to include voxelized transportmore » boosted by Woodcock tracking, faster electron/positron propagation in a magnetic field, and several features that make gPENELOPE highly user-friendly. Moreover, we incorporated the vendor-provided MRIdian head model into the code. We performed a set of experimental measurements on MRIdian to examine the accuracy of both the head model and gPENELOPE, and then applied gPENELOPE toward independent validation of patient doses calculated by MRIdian’s KMC. Results: We achieve an average acceleration factor of 152 compared to the original single-thread FORTRAN implementation with the original accuracy preserved. For 16 treatment plans including stomach (4), lung (2), liver (3), adrenal gland (2), pancreas (2), spleen (1), mediastinum (1) and breast (1), the MRIdian dose calculation engine agrees with gPENELOPE with a mean gamma passing rate of 99.1% ± 0.6% (2%/2 mm). Conclusions: We developed a Monte Carlo simulation platform based on a GPU-accelerated version of PENELOPE. We validated that both the vendor provided head model and fast Monte Carlo engine used by the MRIdian system are accurate in modeling radiation transport in a patient using 2%/2 mm gamma criteria. Future applications of this platform will include dose validation and accumulation, IMRT optimization, and dosimetry system modeling for next generation MR-IGRT systems.« less

  2. Accelerated Partial Breast Irradiation: What is Dosimetric Effect of Advanced Technology Approaches?

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Moran, Jean M.; Ben-David, Merav A.; Marsh, Robin B.

    2009-09-01

    Purpose: The present treatment planning study compared whole breast radiotherapy (WBRT) to accelerated partial breast irradiation (APBI) for different external beam techniques and geometries (e.g., free breathing [FB] and deep inspiration breath hold [DIBH]). Methods and Materials: After approval by our institutional review board, a treatment planning study was performed of 10 patients with left-sided Stage 0-I breast cancer enrolled in a Phase I-II study of APBI using intensity-modulated radiotherapy (IMRT). After lumpectomy, patients underwent planning computed tomography scans during FB and using an active breathing control device at DIBH. For the FB geometry, standard WBRT and three-dimensional conformal radiotherapymore » (3D-CRT) APBI plans were created. For the DIBH geometry with active breathing control, WBRT, 3D-CRT, and IMRT APBI plans were created. Results: All APBI techniques had excellent planning target volume coverage. The maximal planning target volume dose was reduced from 116% of the prescription dose to 108% with the IMRT(DIBH) APBI plan. The maximal heart dose was >30 Gy for the WBRT techniques, 8.2 Gy for 3D-CRT(FB), and <5.0 Gy for 3D-CRT(DIBH) and IMRT(DIBH) techniques. The mean left anterior descending artery dose was significantly reduced from 11.4 Gy with WBRT(FB) to 4.2 with WBRT(DIBH) and <2.0 Gy with all APBI techniques. Conclusion: Although planning target volume coverage was acceptable with all techniques, the plans using the DIBH geometry resulted in a marked reduction in the normal tissue dose compared with WBRT planned in the absence of cardiac blocking. Additional study is needed to determine whether these techniques result in clinical benefits.« less

  3. Optimization of the temporal pattern of radiation: An IMRT based study

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Altman, Michael B.; Chmura, Steven J.; Deasy, Joseph O.

    Purpose: To investigate how the temporal pattern of dose applied during a single-intensity modulated radiation therapy (IMRT) fraction can be arranged to maximize or minimize cell kill. Methods and Materials: Using the linear-quadratic repair-time model and a simplified IMRT delivery pattern model, the surviving fraction of cells for a single fraction was calculated for all permutations of the dose delivery pattern for an array of clinically based IMRT cases. Maximization of cell kill was achieved by concentrating the highest doses in the middle of a fraction, while minimization was achieved by spreading the highest doses between the beginning and end.more » The percent difference between maximum and minimum cell kill (%Diff{sub min/max}) and the difference between maximum and minimum total doses normalized to 2 Gy/fx ({delta}NTD{sub 2Gy}) was calculated for varying fraction durations (T), {alpha}/{beta} ratios, and doses/fx. Results: %Diff{sub min/max} and {delta}NTD{sub 2Gy} both increased with increasing T and with decreasing {alpha}/{beta}. The largest increases occurred with dose/fx. With {alpha}/{beta} = 3 Gy and 30 min/fx, %Diff{sub min/max} ranged from 2.7-5.3% for 2 Gy/fx to 48.6-74.1% for 10 Gy/fx, whereas {delta}NTD{sub 2Gy} ranged from 1.2 Gy-2.4 Gy for 30 fractions of 2 Gy/fx to 2.3-4.8 Gy for 2 fractions of 10.84 Gy/fx. Using {alpha}/{beta} = 1.5 Gy, an analysis of prostate hypofractionation schemes yielded differences in clinical outcome based on the pattern of applied dose ranging from 3.2%-6.1% of the treated population. Conclusions: Rearrangement of the temporal pattern of dose for a single IMRT fraction could be used to optimize cell kill and to directly, though modestly, affect treatment outcome.« less

  4. 3D conformal planning using low segment multi-criteria IMRT optimization

    PubMed Central

    Khan, Fazal; Craft, David

    2014-01-01

    Purpose To evaluate automated multicriteria optimization (MCO) – designed for intensity modulated radiation therapy (IMRT), but invoked with limited segmentation – to efficiently produce high quality 3D conformal radiation therapy (3D-CRT) plans. Methods Ten patients previously planned with 3D-CRT to various disease sites (brain, breast, lung, abdomen, pelvis), were replanned with a low-segment inverse multicriteria optimized technique. The MCO-3D plans used the same beam geometry of the original 3D plans, but were limited to an energy of 6 MV. The MCO-3D plans were optimized using fluence-based MCO IMRT and then, after MCO navigation, segmented with a low number of segments. The 3D and MCO-3D plans were compared by evaluating mean dose for all structures, D95 (dose that 95% of the structure receives) and homogeneity indexes for targets, D1 and clinically appropriate dose volume objectives for individual organs at risk (OARs), monitor units (MUs), and physician preference. Results The MCO-3D plans reduced the OAR mean doses (41 out of a total of 45 OARs had a mean dose reduction, p<<0.01) and monitor units (seven out of ten plans have reduced MUs; the average reduction is 17%, p=0.08) while maintaining clinical standards on coverage and homogeneity of target volumes. All MCO-3D plans were preferred by physicians over their corresponding 3D plans. Conclusion High quality 3D plans can be produced using MCO-IMRT optimization, resulting in automated field-in-field type plans with good monitor unit efficiency. Adopting this technology in a clinic could improve plan quality, and streamline treatment plan production by utilizing a single system applicable to both IMRT and 3D planning. PMID:25413405

  5. Improving IMRT delivery efficiency using intensity limits during inverse planning.

    PubMed

    Coselmon, Martha M; Moran, Jean M; Radawski, Jeffrey D; Fraass, Benedick A

    2005-05-01

    Inverse planned intensity modulated radiotherapy (IMRT) fields can be highly modulated due to the large number of degrees of freedom involved in the inverse planning process. Additional modulation typically results in a more optimal plan, although the clinical rewards may be small or offset by additional delivery complexity and/or increased dose from transmission and leakage. Increasing modulation decreases delivery efficiency, and may lead to plans that are more sensitive to geometrical uncertainties. The purpose of this work is to assess the use of maximum intensity limits in inverse IMRT planning as a simple way to increase delivery efficiency without significantly affecting plan quality. Nine clinical cases (three each for brain, prostate, and head/neck) were used to evaluate advantages and disadvantages of limiting maximum intensity to increase delivery efficiency. IMRT plans were generated using in-house protocol-based constraints and objectives for the brain and head/neck, and RTOG 9406 dose volume objectives in the prostate. Each case was optimized at a series of maximum intensity ratios (the product of the maximum intensity and the number of beams divided by the prescribed dose to the target volume), and evaluated in terms of clinical metrics, dose-volume histograms, monitor units (MU) required per fraction (SMLC and DMLC delivery), and intensity map variation (a measure of the beam modulation). In each site tested, it was possible to reduce total monitor units by constraining the maximum allowed intensity without compromising the clinical acceptability of the plan. Monitor unit reductions up to 38% were observed for SMLC delivery, while reductions up to 29% were achieved for DMLC delivery. In general, complicated geometries saw a smaller reduction in monitor units for both delivery types, although DMLC delivery required significantly more monitor units in all cases. Constraining the maximum intensity in an inverse IMRT plan is a simple way to improve

  6. SU-F-T-256: 4D IMRT Planning Using An Early Prototype GPU-Enabled Eclipse Workstation

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hagan, A; Modiri, A; Sawant, A

    Purpose: True 4D IMRT planning, based on simultaneous spatiotemporal optimization has been shown to significantly improve plan quality in lung radiotherapy. However, the high computational complexity associated with such planning represents a significant barrier to widespread clinical deployment. We introduce an early prototype GPU-enabled Eclipse workstation for inverse planning. To our knowledge, this is the first GPUintegrated Eclipse system demonstrating the potential for clinical translation of GPU computing on a major commercially-available TPS. Methods: The prototype system comprised of four NVIDIA Tesla K80 GPUs, with a maximum processing capability of 8.5 Tflops per K80 card. The system architecture consisted ofmore » three key modules: (i) a GPU-based inverse planning module using a highly-parallelizable, swarm intelligence-based global optimization algorithm, (ii) a GPU-based open-source b-spline deformable image registration module, Elastix, and (iii) a CUDA-based data management module. For evaluation, aperture fluence weights in an IMRT plan were optimized over 9 beams,166 apertures and 10 respiratory phases (14940 variables) for a lung cancer case (GTV = 95 cc, right lower lobe, 15 mm cranio-caudal motion). Sensitivity of the planning time and memory expense to parameter variations was quantified. Results: GPU-based inverse planning was significantly accelerated compared to its CPU counterpart (36 vs 488 min, for 10 phases, 10 search agents and 10 iterations). The optimized IMRT plan significantly improved OAR sparing compared to the original internal target volume (ITV)-based clinical plan, while maintaining prescribed tumor coverage. The dose-sparing improvements were: Esophagus Dmax 50%, Heart Dmax 42% and Spinal cord Dmax 25%. Conclusion: Our early prototype system demonstrates that through massive parallelization, computationally intense tasks such as 4D treatment planning can be accomplished in clinically feasible timeframes. With further

  7. SU-F-T-391: Comparative Study of Treatment Planning Between IMRT and IMAT for Malignant Pleural Mesothelioma

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Duan, J

    Purpose: The purpose of this study was to compare the dosimetric differences between intensitymodulated radiation therapy (IMRT) and intensity modulated arc therapy (IMAT) for malignant pleural mesothelioma (MPM) patients with regard to the sparing effect on organs at risk (OARs), plan quality, and delivery efficiency. Methods: Ten MPM patients were recruited in this study. To avoid the inter-operator variability, IMRT and IMAT plans for each patient were performed by one experienced dosimetrist. The treatment planning optimization process was carried out using the Eclipse 13.0 software. For a fair comparison, the planning target volume (PTV) coverage of the two plans wasmore » normalized to the same level. The treatment plans were evaluated on the following dosimetric variables: conformity index (CI) and homogeneity index (HI) for PTV, OARs dose, and the delivery efficiency for each plan. Results: All plans satisfied clinical requirements. The IMAT plans gained better CI and HI. The IMRT plans performed better sparing for heart and lung. Less MUs and control points were found in the IMAT plans. IMAT shortened delivery time compared with IMRT. Conclusion: For MPM, IMAT gains better conformity and homogeneity for PTV with IMRT, but increases the irradiation dose for OARs. IMAT shows an advantage in delivery efficiency.« less

  8. Investigation of pulsed IMRT and VMAT for re-irradiation treatments: dosimetric and delivery feasibilities

    NASA Astrophysics Data System (ADS)

    Lin, Mu-Han; Price, Robert A., Jr.; Li, Jinsheng; Kang, Shengwei; Li, Jie; Ma, C.-M.

    2013-11-01

    Many tumor cells demonstrate hyperradiosensitivity at doses below ˜50 cGy. Together with the increased normal tissue repair under low dose rate, the pulsed low dose rate radiotherapy (PLDR), which separates a daily fractional dose of 200 cGy into 10 pulses with 3 min interval between pulses (˜20 cGy/pulse and effective dose rate 6.7 cGy min-1), potentially reduces late normal tissue toxicity while still providing significant tumor control for re-irradiation treatments. This work investigates the dosimetric and technical feasibilities of intensity modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT)-based PLDR treatments using Varian Linacs. Twenty one cases (12 real re-irradiation cases) including treatment sites of pancreas, prostate, pelvis, lung, head-and-neck, and breast were recruited for this study. The lowest machine operation dose rate (100 MU min-1) was employed in the plan delivery. Ten-field step-and-shoot IMRT and dual-arc VMAT plans were generated using the Eclipse TPS with routine planning strategies. The dual-arc plans were delivered five times to achieve a 200 cGy daily dose (˜20 cGy arc-1). The resulting plan quality was evaluated according to the heterogeneity and conformity indexes (HI and CI) of the planning target volume (PTV). The dosimetric feasibility of retaining the hyperradiosensitivity for PLDR was assessed based on the minimum and maximum dose in the target volume from each pulse. The delivery accuracy of VMAT and IMRT at the 100 MU min-1 machine operation dose rate was verified using a 2D diode array and ion chamber measurements. The delivery reproducibility was further investigated by analyzing the Dynalog files of repeated deliveries. A comparable plan quality was achieved by the IMRT (CI 1.10-1.38 HI 1.04-1.10) and the VMAT (CI 1.08-1.26 HI 1.05-1.10) techniques. The minimum/maximum PTV dose per pulse is 7.9 ± 5.1 cGy/33.7 ± 6.9 cGy for the IMRT and 12.3 ± 4.1 cGy/29.2 ± 4.7 cGy for the VMAT. Six out of

  9. IMRT treatment of anal cancer with a scrotal shield

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hood, Rodney C., E-mail: Rodney.Hood@duke.edu; Wu, Q. Jackie; McMahon, Ryan

    The risk of sterility in males undergoing radiotherapy in the pelvic region indicates the use of a shielding device, which offers protection to the testes for patients wishing to maintain fertility. The use of such devices in the realm of intensity-modulated radiotherapy (IMRT) in the pelvic region can pose many obstacles during simulation, treatment planning, and delivery of radiotherapy. This work focuses on the development and execution of an IMRT plan for the treatment of anal cancer using a scrotal shielding device on a clinical patient. An IMRT plan was developed using Eclipse treatment planning system (Varian Medical Systems, Palomore » Alto, CA), using a wide array of gantry angles as well as fixed jaw and fluence editing techniques. When possible, the entire target volume was encompassed by the treatment field. When the beam was incident on the scrotal shield, the jaw was fixed to avoid the device and the collimator rotation optimized to irradiate as much of the target as possible. This technique maximizes genital sparing and allows minimal irradiation of the gonads. When this fixed-jaw technique was found to compromise adequate coverage of the target, manual fluence editing techniques were used to avoid the shielding device. Special procedures for simulation, imaging, and treatment verification were also developed. In vivo dosimetry was used to verify and ensure acceptable dose to the gonads. The combination of these techniques resulted in a highly conformal plan that spares organs and risk and avoids the genitals as well as entrance of primary radiation onto the shielding device.« less

  10. Hippocampal-Sparing Whole-Brain Radiotherapy: A 'How-To' Technique Using Helical Tomotherapy and Linear Accelerator-Based Intensity-Modulated Radiotherapy

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Gondi, Vinai; Tolakanahalli, Ranjini; Mehta, Minesh P.

    2010-11-15

    Purpose: Sparing the hippocampus during cranial irradiation poses important technical challenges with respect to contouring and treatment planning. Herein we report our preliminary experience with whole-brain radiotherapy using hippocampal sparing for patients with brain metastases. Methods and Materials: Five anonymous patients previously treated with whole-brain radiotherapy with hippocampal sparing were reviewed. The hippocampus was contoured, and hippocampal avoidance regions were created using a 5-mm volumetric expansion around the hippocampus. Helical tomotherapy and linear accelerator (LINAC)-based intensity-modulated radiotherapy (IMRT) treatment plans were generated for a prescription dose of 30 Gy in 10 fractions. Results: On average, the hippocampal avoidance volume wasmore » 3.3 cm{sup 3}, occupying 2.1% of the whole-brain planned target volume. Helical tomotherapy spared the hippocampus, with a median dose of 5.5 Gy and maximum dose of 12.8 Gy. LINAC-based IMRT spared the hippocampus, with a median dose of 7.8 Gy and maximum dose of 15.3 Gy. On a per-fraction basis, mean dose to the hippocampus (normalized to 2-Gy fractions) was reduced by 87% to 0.49 Gy{sub 2} using helical tomotherapy and by 81% to 0.73 Gy{sub 2} using LINAC-based IMRT. Target coverage and homogeneity was acceptable with both IMRT modalities, with differences largely attributed to more rapid dose fall-off with helical tomotherapy. Conclusion: Modern IMRT techniques allow for sparing of the hippocampus with acceptable target coverage and homogeneity. Based on compelling preclinical evidence, a Phase II cooperative group trial has been developed to test the postulated neurocognitive benefit.« less

  11. Poster - Thur Eve - 57: Craniospinal irradiation with jagged-junction IMRT approach without beam edge matching for field junctions.

    PubMed

    Cao, F; Ramaseshan, R; Corns, R; Harrop, S; Nuraney, N; Steiner, P; Aldridge, S; Liu, M; Carolan, H; Agranovich, A; Karva, A

    2012-07-01

    Craniospinal irradiation were traditionally treated the central nervous system using two or three adjacent field sets. A intensity-modulated radiotherapy (IMRT) plan (Jagged-Junction IMRT) which overcomes problems associated with field junctions and beam edge matching, improves planning and treatment setup efficiencies with homogenous target dose distribution was developed. Jagged-Junction IMRT was retrospectively planned on three patients with prescription of 36 Gy in 20 fractions and compared to conventional treatment plans. Planning target volume (PTV) included the whole brain and spinal canal to the S3 vertebral level. The plan employed three field sets, each with a unique isocentre. One field set with seven fields treated the cranium. Two field sets treated the spine, each set using three fields. Fields from adjacent sets were overlapped and the optimization process smoothly integrated the dose inside the overlapped junction. For the Jagged-Junction IMRT plans vs conventional technique, average homogeneity index equaled 0.08±0.01 vs 0.12±0.02, and conformity number equaled 0.79±0.01 vs 0.47±0.12. The 95% isodose surface covered (99.5±0.3)% of the PTV vs (98.1±2.0)%. Both Jagged-Junction IMRT plans and the conventional plans had good sparing of the organs at risk. Jagged-Junction IMRT planning provided good dose homogeneity and conformity to the target while maintaining a low dose to the organs at risk. Jagged-Junction IMRT optimization smoothly distributed dose in the junction between field sets. Since there was no beam matching, this treatment technique is less likely to produce hot or cold spots at the junction in contrast to conventional techniques. © 2012 American Association of Physicists in Medicine.

  12. Carcinoma of the anal canal: Intensity modulated radiation therapy (IMRT) versus three-dimensional conformal radiation therapy (3DCRT)

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sale, Charlotte; Moloney, Phillip; Mathlum, Maitham

    Patients with anal canal carcinoma treated with standard conformal radiotherapy frequently experience severe acute and late toxicity reactions to the treatment area. Roohipour et al. (Dis Colon Rectum 2008; 51: 147–53) stated a patient's tolerance of chemoradiation to be an important prediction of treatment success. A new intensity modulated radiation therapy (IMRT) technique for anal carcinoma cases has been developed at the Andrew Love Cancer Centre aimed at reducing radiation to surrounding healthy tissue. A same-subject repeated measures design was used for this study, where five anal carcinoma cases at the Andrew Love Cancer Centre were selected. Conformal and IMRTmore » plans were generated and dosimetric evaluations were performed. Each plan was prescribed a total of 54 Gray (Gy) over a course of 30 fractions to the primary site. The IMRT plans resulted in improved dosimetry to the planning target volume (PTV) and reduction in radiation to the critical structures (bladder, external genitalia and femoral heads). Statistically there was no difference between the IMRT and conformal plans in the dose to the small and large bowel; however, the bowel IMRT dose–volume histogram (DVH) doses were consistently lower. The IMRT plans were superior to the conformal plans with improved dose conformity and reduced radiation to the surrounding healthy tissue. Anecdotally it was found that patients tolerated the IMRT treatment better than the three-dimensional (3D) conformal radiation therapy. This study describes and compares the planning techniques.« less

  13. Intensity modulated radiotherapy (IMRT) in the treatment of children and adolescents--a single institution's experience and a review of the literature.

    PubMed

    Sterzing, Florian; Stoiber, Eva M; Nill, Simeon; Bauer, Harald; Huber, Peter; Debus, Jürgen; Münter, Marc W

    2009-09-23

    While IMRT is widely used in treating complex oncological cases in adults, it is not commonly used in pediatric radiation oncology for a variety of reasons. This report evaluates our 9 year experience using stereotactic-guided, inverse planned intensity-modulated radiotherapy (IMRT) in children and adolescents in the context of the current literature. Between 1999 and 2008 thirty-one children and adolescents with a mean age of 14.2 years (1.5 - 20.5) were treated with IMRT in our department. This heterogeneous group of patients consisted of 20 different tumor entities, with Ewing's sarcoma being the largest (5 patients), followed by juvenile nasopharyngeal fibroma, esthesioneuroblastoma and rhabdomyosarcoma (3 patients each). In addition a review of the available literature reporting on technology, quality, toxicity, outcome and concerns of IMRT was performed. With IMRT individualized dose distributions and excellent sparing of organs at risk were obtained in the most challenging cases. This was achieved at the cost of an increased volume of normal tissue receiving low radiation doses. Local control was achieved in 21 patients. 5 patients died due to progressive distant metastases. No severe acute or chronic toxicity was observed. IMRT in the treatment of children and adolescents is feasible and was applied safely within the last 9 years at our institution. Several reports in literature show the excellent possibilities of IMRT in selective sparing of organs at risk and achieving local control. In selected cases the quality of IMRT plans increases the therapeutic ratio and outweighs the risk of potentially increased rates of secondary malignancies by the augmented low dose exposure.

  14. Detection of IMRT delivery errors based on a simple constancy check of transit dose by using an EPID

    NASA Astrophysics Data System (ADS)

    Baek, Tae Seong; Chung, Eun Ji; Son, Jaeman; Yoon, Myonggeun

    2015-11-01

    Beam delivery errors during intensity modulated radiotherapy (IMRT) were detected based on a simple constancy check of the transit dose by using an electronic portal imaging device (EPID). Twenty-one IMRT plans were selected from various treatment sites, and the transit doses during treatment were measured by using an EPID. Transit doses were measured 11 times for each course of treatment, and the constancy check was based on gamma index (3%/3 mm) comparisons between a reference dose map (the first measured transit dose) and test dose maps (the following ten measured dose maps). In a simulation using an anthropomorphic phantom, the average passing rate of the tested transit dose was 100% for three representative treatment sites (head & neck, chest, and pelvis), indicating that IMRT was highly constant for normal beam delivery. The average passing rate of the transit dose for 1224 IMRT fields from 21 actual patients was 97.6% ± 2.5%, with the lower rate possibly being due to inaccuracies of patient positioning or anatomic changes. An EPIDbased simple constancy check may provide information about IMRT beam delivery errors during treatment.

  15. TU-G-BRD-03: IMRT Dosimetry Differences in An Institution with Community and Academic Model

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Srivastava, S; Indiana University School of Medicine, Indianapolis, IN; Andersen, A

    Purpose: Radiation outcome among institutions can be interpreted meaningfully if the dose delivery and prescription to the target volume is documented accurately and consistently. ICRU-83 recommended specific guidelines in IMRT for target volume definitions and dose reporting. This retrospective study evaluates the pattern of IMRT dose prescription and recording in an academic institution (AI) and a community hospital (CH) models in a single institution with reference to ICRU-83 recommendation. Materials & Methods: Dosimetric information of 625 (500 from academic and 125 from community) patients treated with IMRT was collected retrospectively from the AI and a CH. The dose-volume histogram (DVH)more » for the target volume of each patient was extracted. Standard dose parameters such as D2, D50, D95, D98, D100, as well as the homogeneity index (HI) defined as (D2-D98)/D50 and monitor units (MUs) were collected. Results: Significant dosimetric variations were observed in disease sites and between AI and CH. The variation in the mean value of D95 for AI is 98.48±4.12 and for CH is 96.41±4.13. A similar pattern was noticed for D50 (104.18±6.04 for AI and 101.05±3.49 for CH). Thus, nearly 95% of patients received dosage higher than 100% to the site viewed by D50 and varied between AI and CH models. The average variation of HI is found to be 0.12±0.08 and 0.11±0.08 for AI and CH model, showing better IMRT treatment plans for academic model compared to community. Conclusion: Even with the implementation of ICRU-83 guidelines, there is a large variation in dose prescription and delivery in IMRT. The variation is institution and site specific. For any meaningful comparison of the IMRT outcome, strict guidelines for dose reporting should be maintained in every institution.« less

  16. SU-F-T-378: Evaluation of Dose-Volume Variability and Parameters Between Prostate IMRT and VMAT Plans

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Chow, J; Jiang, R; Kiciak, A

    2016-06-15

    Purpose: This study compared the rectal dose-volume consistency, equivalent uniform dose (EUD) and normal tissue complication probability (NTCP) in prostate intensity modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT). Methods: For forty prostate IMRT and fifty VMAT patients treated using the same dose prescription (78 Gy/39 fraction) and dose-volume criteria in inverse planning optimization, the rectal EUD and NTCP were calculated for each patient. The rectal dose-volume consistency, showing the variability of dose-volume histogram (DVH) among patients, was defined and calculated based on the deviation between the mean and corresponding rectal DVH. Results: From both the prostate IMRT andmore » VMAT plans, the rectal EUD and NTCP were found decreasing with the rectal volume. The decrease rates for the IMRT plans (EUD = 0.47 × 10{sup −3} Gy cm{sup −3} and NTCP = 3.94 × 10{sup −2} % cm{sup −3}) were higher than those for the VMAT (EUD = 0.28 × 10{sup −3} Gy cm{sup −3} and NTCP = 2.61 × 10{sup −2} % cm{sup −3}). In addition, the dependences of the rectal EUD and NTCP on the dose-volume consistency were found very similar between the prostate IMRT and VMAT plans. This shows that both delivery techniques have similar variations of the rectal EUD and NTCP on the dose-volume consistency. Conclusion: Dependences of the dose-volume consistency on the rectal EUD and NTCP were compared between the prostate IMRT and VMAT plans. It is concluded that both rectal EUD and NTCP decreased with an increase of the rectal volume. The variation rates of the rectal EUD and NTCP on the rectal volume were higher for the IMRT plans than VMAT. However, variations of the rectal dose-volume consistency on the rectal EUD and NTCP were found not significant for both delivery techniques.« less

  17. Hematologic Toxicity in RTOG 0418: A Phase 2 Study of Postoperative IMRT for Gynecologic Cancer

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Klopp, Ann H., E-mail: aklopp@mdanderson.org; Moughan, Jennifer; Portelance, Lorraine

    2013-05-01

    Purpose: Intensity modulated radiation therapy (IMRT), compared with conventional 4-field treatment, can reduce the volume of bone marrow irradiated. Pelvic bone marrow sparing has produced a clinically significant reduction in hematologic toxicity (HT). This analysis investigated HT in Radiation Therapy Oncology Group (RTOG) 0418, a prospective study to test the feasibility of delivering postoperative IMRT for cervical and endometrial cancer in a multiinstitutional setting. Methods and Materials: Patients in the RTOG 0418 study were treated with postoperative IMRT to 50.4 Gy to the pelvic lymphatics and vagina. Endometrial cancer patients received IMRT alone, whereas patients with cervical cancer received IMRTmore » and weekly cisplatin (40 mg/m{sup 2}). Pelvic bone marrow was defined within the treatment field by using a computed tomography density-based autocontouring algorithm. The volume of bone marrow receiving 10, 20, 30, and 40 Gy and the median dose to bone marrow were correlated with HT, graded by Common Terminology Criteria for Adverse Events, version 3.0, criteria. Results: Eighty-three patients were eligible for analysis (43 with endometrial cancer and 40 with cervical cancer). Patients with cervical cancer treated with weekly cisplatin and pelvic IMRT had grades 1-5 HT (23%, 33%, 25%, 0%, and 0% of patients, respectively). Among patients with cervical cancer, 83% received 5 or more cycles of cisplatin, and 90% received at least 4 cycles of cisplatin. The median percentage volume of bone marrow receiving 10, 20, 30, and 40 Gy in all 83 patients, respectively, was 96%, 84%, 61%, and 37%. Among cervical cancer patients with a V40 >37%, 75% had grade 2 or higher HT compared with 40% of patients with a V40 less than or equal to 37% (P =.025). Cervical cancer patients with a median bone marrow dose of >34.2 Gy also had higher rates of grade ≥2 HT than did those with a dose of ≤34.2 Gy (74% vs 43%, P=.049). Conclusions: Pelvic IMRT with weekly

  18. A quantitative study of IMRT delivery effects in commercial planning systems for the case of oesophagus and prostate tumours.

    PubMed

    Seco, J; Clark, C H; Evans, P M; Webb, S

    2006-05-01

    This study focuses on understanding the impact of intensity-modulated radiotherapy (IMRT) delivery effects when applied to plans generated by commercial treatment-planning systems such as Pinnacle (ADAC Laboratories Inc.) and CadPlan/Helios (Varian Medical Systems). These commercial planning systems have had several version upgrades (with improvements in the optimization algorithm), but the IMRT delivery effects have not been incorporated into the optimization process. IMRT delivery effects include head-scatter fluence from IMRT fields, transmission through leaves and the effect of the rounded shape of the leaf ends. They are usually accounted for after optimization when leaf sequencing the "optimal" fluence profiles, to derive the delivered fluence profile. The study was divided into two main parts: (a) analysing the dose distribution within the planning-target volume (PTV), produced by each of the commercial treatment-planning systems, after the delivered fluence had been renormalized to deliver the correct dose to the PTV; and (b) studying the impact of the IMRT delivery technique on the surrounding critical organs such as the spinal cord, lungs, rectum, bladder etc. The study was performed for tumours of (i) the oesophagus and (ii) the prostate and pelvic nodes. An oesophagus case was planned with the Pinnacle planning system for IMRT delivery, via multiple-static fields (MSF) and compensators, using the Elekta SL25 with a multileaf collimator (MLC) component. A prostate and pelvic nodes IMRT plan was performed with the Cadplan/Helios system for a dynamic delivery (DMLC) using the Varian 120-leaf Millennium MLC. In these commercial planning systems, since IMRT delivery effects are not included into the optimization process, fluence renormalization is required such that the median delivered PTV dose equals the initial prescribed PTV dose. In preparing the optimum fluence profile for delivery, the PTV dose has been "smeared" by the IMRT delivery techniques. In

  19. TH-C-17A-03: Dynamic Visualization and Dosimetry of IMRT and VMAT Treatment Plans by Video-Rate Imaging of Cherenkov Radiation in Pure Water

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Glaser, A; Andreozzi, J; Davis, S

    Purpose: A novel optical dosimetry technique for the QA and verification of intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT) radiotherapy plans was investigated for the first time by capturing images of the induced Cherenkov radiation in water. Methods: An intensified CCD camera (ICCD) was used to acquire a two-dimensional (2D) projection image of the Cherenkov radiation induced by IMRT and VMAT plans, based on the Task Group 119 C-Shape geometry. Plans were generated using the Varian Eclipse treatment planning system (TPS) and delivered using 6 MV x-rays from a Varian TrueBeam Linear Accelerator (Linac) incident on a watermore » tank. The ICCD acquisition was gated to the Linac, operated for single pulse imaging, and binned to a resolution of 512×512 pixels. The resulting videos were analyzed temporally for regions of interest (ROI) covering the planning target volume (PTV) and organ at risk (OAR) and summed to obtain an overall light distribution, which was compared to the expected dose distribution from the TPS using a gammaindex analysis. Results: The chosen camera settings resulted in data at 23.5 frames per second. Temporal intensity plots of the PTV and OAR ROIs confirmed the preferential delivery of dose to the PTV versus the OAR, and the gamma analysis yielded 95.2% and 95.6% agreement between the light distribution and expected TPS dose distribution based upon a 3% / 3 mm dose difference and distance-to-agreement criterion for the IMRT and VMAT plans respectively. Conclusion: The results from this initial study demonstrate the first documented use of Cherenkov radiation for optical dosimetry of dynamic IMRT and VMAT treatment plans. The proposed modality has several potential advantages over alternative methods including the real-time nature of the acquisition, and upon future refinement may prove to be a robust and novel dosimetry method with both research and clinical applications. NIH R01CA109558 and R21EB

  20. SU-E-T-163: Evaluation of Dose Distributions Recalculated with Per-Field Measurement Data Under the Condition of Respiratory Motion During IMRT for Liver Cancer

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Song, J; Yoon, M; Nam, T

    2014-06-01

    Purpose: The dose distributions within the real volumes of tumor targets and critical organs during internal target volume-based intensity-modulated radiation therapy (ITV-IMRT) for liver cancer were recalculated by applying the effects of actual respiratory organ motion, and the dosimetric features were analyzed through comparison with gating IMRT (Gate-IMRT) plan results. Methods: The 4DCT data for 10 patients who had been treated with Gate-IMRT for liver cancer were selected to create ITV-IMRT plans. The ITV was created using MIM software, and a moving phantom was used to simulate respiratory motion. The period and range of respiratory motion were recorded in allmore » patients from 4DCT-generated movie data, and the same period and range were applied when operating the dynamic phantom to realize coincident respiratory conditions in each patient. The doses were recalculated with a 3 dose-volume histogram (3DVH) program based on the per-field data measured with a MapCHECK2 2-dimensional diode detector array and compared with the DVHs calculated for the Gate-IMRT plan. Results: Although a sufficient prescription dose covered the PTV during ITV-IMRT delivery, the dose homogeneity in the PTV was inferior to that with the Gate-IMRT plan. We confirmed that there were higher doses to the organs-at-risk (OARs) with ITV-IMRT, as expected when using an enlarged field, but the increased dose to the spinal cord was not significant and the increased doses to the liver and kidney could be considered as minor when the reinforced constraints were applied during IMRT plan optimization. Conclusion: Because Gate-IMRT cannot always be considered an ideal method with which to correct the respiratory motional effect, given the dosimetric variations in the gating system application and the increased treatment time, a prior analysis for optimal IMRT method selection should be performed while considering the patient's respiratory condition and IMRT plan results.« less

  1. Comparison of IMRT versus 3D-CRT in the treatment of esophagus cancer: A systematic review and meta-analysis.

    PubMed

    Xu, Dandan; Li, Guowen; Li, Hongfei; Jia, Fei

    2017-08-01

    Esophageal cancer (EC) is a common cancer with high mortality because of its rapid progression and poor prognosis. Radiotherapy is one of the most effective treatments for EC. Three-dimensional conformal radiotherapy (3D-CRT) and intensity-modulated radiotherapy (IMRT) are 2 recently developed radiotherapy techniques. IMRT is believed to be more effective than 3D-CRT in target coverage, dose homogeneity, and reducing toxicity to normal organs. However, these advantages have not been demonstrated in the treatment of EC. This meta-analysis was performed to compare IMRT and 3D-CRT in the treatment of EC in terms of dose-volume histograms and outcomes including survival and toxicity. A literature search was performed in PubMed, Embase, and the Cochrane library databases from their inceptions to Dec 30, 2016. Two authors independently assessed the included studies and extracted data. The average percent irradiated volumes of adjacent noncancerous organs were calculated and compared between IMRT and 3D-CRT. The odds ratio of overall survival (OS), and radiation pneumonitis and radiation esophagitis was also evaluated. Totally 7 studies were included. Of them, 5 studies (80 patients) were included in the dosimetric comparison, 3 studies (871 patients) were included in the OS analysis, and 2 studies (205 patients) were included in the irradiation toxicity analysis. For lung in patients receiving doses ≥20 Gy and heart in patients receiving dose = 50 Gy, the average irradiated volumes of IMRT were less than those from 3D-CRT. IMRT resulted in a higher OS than 3D-CRT. However, no significant difference was observed in the incidence of radiation pneumonitis and radiation esophagitis between 2 radiotherapy techniques. Our data suggest that IMRT-delivered high radiation dose produces significantly less average percent volumes of irradiated lung and heart than 3D-CRT. IMRT is superior to 3D-CRT in the OS of EC while shows no benefit on radiation toxicity.

  2. SU-F-T-288: Impact of Trajectory Log Files for Clarkson-Based Independent Dose Verification of IMRT and VMAT

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Takahashi, R; Kamima, T; Tachibana, H

    2016-06-15

    Purpose: To investigate the effect of the trajectory files from linear accelerator for Clarkson-based independent dose verification in IMRT and VMAT plans. Methods: A CT-based independent dose verification software (Simple MU Analysis: SMU, Triangle Products, Japan) with a Clarksonbased algorithm was modified to calculate dose using the trajectory log files. Eclipse with the three techniques of step and shoot (SS), sliding window (SW) and Rapid Arc (RA) was used as treatment planning system (TPS). In this study, clinically approved IMRT and VMAT plans for prostate and head and neck (HN) at two institutions were retrospectively analyzed to assess the dosemore » deviation between DICOM-RT plan (PL) and trajectory log file (TJ). An additional analysis was performed to evaluate MLC error detection capability of SMU when the trajectory log files was modified by adding systematic errors (0.2, 0.5, 1.0 mm) and random errors (5, 10, 30 mm) to actual MLC position. Results: The dose deviations for prostate and HN in the two sites were 0.0% and 0.0% in SS, 0.1±0.0%, 0.1±0.1% in SW and 0.6±0.5%, 0.7±0.9% in RA, respectively. The MLC error detection capability shows the plans for HN IMRT were the most sensitive and 0.2 mm of systematic error affected 0.7% dose deviation on average. Effect of the MLC random error did not affect dose error. Conclusion: The use of trajectory log files including actual information of MLC location, gantry angle, etc should be more effective for an independent verification. The tolerance level for the secondary check using the trajectory file may be similar to that of the verification using DICOM-RT plan file. From the view of the resolution of MLC positional error detection, the secondary check could detect the MLC position error corresponding to the treatment sites and techniques. This research is partially supported by Japan Agency for Medical Research and Development (AMED)« less

  3. [Comparison of SIB-IMRT treatment plans for upper esophageal carcinoma].

    PubMed

    Fu, Wei-hua; Wang, Lv-hua; Zhou, Zong-mei; Dai, Jian-rong; Hu, Yi-min

    2003-06-01

    To implement simultaneous integrated boost intensity-modulated radiotherapy(SIB-IMRT) plans for upper esophageal carcinoma and investigate the dose profiles of tumor and electively treated region and the dose to organs at risk (OARs). SIB-IMRT plans were designed for two patients with upper esophageal carcinoma. Two target volumes were predefined: PTV1, the target volume of the primary lesion, which was given to 67.2 Gy, and PTV2, the target volume of electively treated region, which was given to 50.4 Gy. With the same dose-volume constraints, but different beams arrangements (3, 5, 7, or 9 equispaced coplanar beams), four plans were generated. Indices, including dose distribution, dose volume histogram (DVH) and conformity index, were used for comparison of these plans. The plan with three intensity-modulated beams could produce good dose distribution for the two target volumes. The dose conformity to targets and the dose to OARs were improved as the beam number increased. The dose distributions in targets changed little when the beam number increased from 7 to 9. Five to seven intensity-modulated beams can produce desirable dose distributions for simultaneous integrated boost (SIB) treatment for upper esophageal carcinoma. The primary tumor can get higher equivalent dose by SIB treatments. It is easier and more efficient to design plans with equispaced coplanar beams. The efficacy of SIB-IMRT remains to be determined by the clinical outcome.

  4. Multi-institutional Comparison of Intensity Modulated Radiation Therapy (IMRT) Planning Strategies and Planning Results for Nasopharyngeal Cancer

    PubMed Central

    Park, Sung Ho; Park, Suk Won; Oh, Do Hoon; Choi, Youngmin; Kim, Jeung Kee; Ahn, Yong Chan; Park, Won; Suh, Hyun Sook; Lee, Rena; Bae, Hoonsik

    2009-01-01

    The intensity-modulated radiation therapy (IMRT) planning strategies for nasopharyngeal cancer among Korean radiation oncology facilities were investigated. Five institutions with IMRT planning capacity using the same planning system were invited to participate in this study. The institutions were requested to produce the best plan possible for 2 cases that would deliver 70 Gy to the planning target volume of gross tumor (PTV1), 59.4 Gy to the PTV2, and 51.5 Gy to the PTV3 in which elective irradiation was required. The advised fractionation number was 33. The planning parameters, resultant dose distributions, and biological indices were compared. We found 2-3-fold variations in the volume of treatment targets. Similar degree of variation was found in the delineation of normal tissue. The physician-related factors in IMRT planning had more influence on the plan quality. The inhomogeneity index of PTV dose ranged from 4 to 49% in Case 1, and from 5 to 46% in Case 2. Variation in tumor control probabilities for the primary lesion and involved LNs was less marked. Normal tissue complication probabilities for parotid glands and skin showed marked variation. Results from this study suggest that greater efforts in providing training and continuing education in terms of IMRT planning parameters usually set by physician are necessary for the successful implementation of IMRT. PMID:19399266

  5. Prostate Dose Escalation by Innovative Inverse Planning-Driven IMRT

    DTIC Science & Technology

    2005-11-01

    Galvin, J. M.; Low, D.; Palta , J. R.; Rosen, I.; Sharpe, M. B.; Xia, P.; Xiao, Y.; Xing, L.; Yu, C. X., Guidance document on delivery, treatment planning... Palta , J., Implementing IMRT in clinical practice: ajoint document of the American Society for Therapeutic Radiology and Oncology and the American

  6. Confidence limit variation for a single IMRT system following the TG119 protocol.

    PubMed

    Gordon, J D; Krafft, S P; Jang, S; Smith-Raymond, L; Stevie, M Y; Hamilton, R J

    2011-03-01

    To evaluate the robustness of TG119-based quality assurance metrics for an IMRT system. Four planners constructed treatment plans for the five IMRT test cases described in TG119. All plans were delivered to a 30 cm x 30 cm x 15 cm solid water phantom in one treatment session in order to minimize session-dependent variation from phantom setup, film quality, machine performance, etc. Composite measurements utilized film and an ionization chamber. Per-field measurements were collected using a diode array device at an effective depth of 5 cm. All data collected were analyzed using the TG119 specifications to determine the confidence limit values for each planner separately and then compared. The mean variance of ion chamber measurements for each planner was within 1.7% of the planned dose. The resulting confidence limits were 3.13%, 1.98%, 3.65%, and 4.39%. Confidence limit values determined by composite film analysis were 8.06%, 13.4%, 9.30%, and 16.5%. Confidence limits from per-field measurements were 1.55%, 0.00%, 0.00%, and 2.89%. For a single IMRT system, the accuracy assessment provided by TG119-based quality assurance metrics showed significant variations in the confidence limits between planners across all composite and per-field evaluations. This observed variation is likely due to the different levels of modulation between each planner's set of plans. Performing the TG119 evaluation using plans produced by a single planner may not provide an adequate estimation of IMRT system accuracy.

  7. SU-F-J-124: Reduction in Dosimetric Impact of Motion Using VMAT Compared to IMRT in Hypofractionated Prostate Cancer Patients

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ravindranath, B; Xiong, J; Happersett, L

    2016-06-15

    Purpose: To quantify and compare the dosimetric impact of motion management correction strategies during VMAT and IMRT for hypofractionated prostate treatment. Methods: Two arc VMAT and 9 field IMRT plans were generated for two prostate cancer patients undergoing hypofractionated radiotherapy (7.5Gy × 5 and 8Gy × 5). 212 motion traces were retrospectively extracted from treatment records of prostate cancer patients with implanted Calypso beacons. Dose to the CTV and normal tissues was reconstructed for each trace and plan taking into account the actual treatment delivery time. Following motion correction scenarios were simulated: (1) VMAT plan – (a) No correction, (b)more » correction between arcs, (c) correction every 20 degrees of gantry rotation and (2) IMRT plan - (a) No correction,(b) correction between fields. Two mm action threshold for position correction was assumed. The 5–95% confidence interval (CI) range was extracted from the family of DVHs for each correction scenario. Results: Treatment duration for 8Gy plan (VMAT vs IMRT) was 3 vs 12 mins and for 7.5Gy plan was 3 vs 9 mins. In the absence of correction, the VMAT 5–−95% CI dose spread was, on average, less than the IMRT dose spread by 2% for CTVD95, 9% for rectalwall (RW) D1cc and 9% for bladderwall (BW) D53. Further, VMAT b/w arcs correction strategy reduced the spread about the planned value compared to IMRT b/w fields correction by: 1% for CTVD95, 2.6% for RW1cc and 2% for BWD53. VMAT 20 degree strategy led to greater reduction in dose spread compared to IMRT by: 2% for CTVD95, 4.5% for RW1cc and 6.7% for BWD53. Conclusion: In the absence of a correction strategy, the limited motion during VMAT’s shorter delivery times translates into less motion-induced dosimetric degradation than IMRT. Performing limited periodic motion correction during VMAT can yield excellent conformity to planned values that is superior to IMRT. This work was partially supported by Varian Medical Systems.« less

  8. IMRT verification using a radiochromic/optical-CT dosimetry system

    NASA Astrophysics Data System (ADS)

    Oldham, Mark; Guo, Pengyi; Gluckman, Gary; Adamovics, John

    2006-12-01

    This work represents our first experiences relating to IMRT verification using a relatively new 3D dosimetry system consisting of a PRESAGETM dosimeter (Heuris Inc, Pharma LLC) and an optical-CT scanning system (OCTOPUSTM TM MGS Inc). This work builds in a step-wise manner on prior work in our lab.

  9. Experimental verification of a Monte Carlo-based MLC simulation model for IMRT dose calculations in heterogeneous media

    NASA Astrophysics Data System (ADS)

    Tyagi, N.; Curran, B. H.; Roberson, P. L.; Moran, J. M.; Acosta, E.; Fraass, B. A.

    2008-02-01

    IMRT often requires delivering small fields which may suffer from electronic disequilibrium effects. The presence of heterogeneities, particularly low-density tissues in patients, complicates such situations. In this study, we report on verification of the DPM MC code for IMRT treatment planning in heterogeneous media, using a previously developed model of the Varian 120-leaf MLC. The purpose of this study is twofold: (a) design a comprehensive list of experiments in heterogeneous media for verification of any dose calculation algorithm and (b) verify our MLC model in these heterogeneous type geometries that mimic an actual patient geometry for IMRT treatment. The measurements have been done using an IMRT head and neck phantom (CIRS phantom) and slab phantom geometries. Verification of the MLC model has been carried out using point doses measured with an A14 slim line (SL) ion chamber inside a tissue-equivalent and a bone-equivalent material using the CIRS phantom. Planar doses using lung and bone equivalent slabs have been measured and compared using EDR films (Kodak, Rochester, NY).

  10. Plan averaging for multicriteria navigation of sliding window IMRT and VMAT

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Craft, David, E-mail: dcraft@partners.org; Papp, Dávid; Unkelbach, Jan

    2014-02-15

    Purpose: To describe a method for combining sliding window plans [intensity modulated radiation therapy (IMRT) or volumetric modulated arc therapy (VMAT)] for use in treatment plan averaging, which is needed for Pareto surface navigation based multicriteria treatment planning. Methods: The authors show that by taking an appropriately defined average of leaf trajectories of sliding window plans, the authors obtain a sliding window plan whose fluence map is the exact average of the fluence maps corresponding to the initial plans. In the case of static-beam IMRT, this also implies that the dose distribution of the averaged plan is the exact dosimetricmore » average of the initial plans. In VMAT delivery, the dose distribution of the averaged plan is a close approximation of the dosimetric average of the initial plans. Results: The authors demonstrate the method on three Pareto optimal VMAT plans created for a demanding paraspinal case, where the tumor surrounds the spinal cord. The results show that the leaf averaged plans yield dose distributions that approximate the dosimetric averages of the precomputed Pareto optimal plans well. Conclusions: The proposed method enables the navigation of deliverable Pareto optimal plans directly, i.e., interactive multicriteria exploration of deliverable sliding window IMRT and VMAT plans, eliminating the need for a sequencing step after navigation and hence the dose degradation that is caused by such a sequencing step.« less

  11. A GPU-accelerated Monte Carlo dose calculation platform and its application toward validating an MRI-guided radiation therapy beam model

    PubMed Central

    Wang, Yuhe; Mazur, Thomas R.; Green, Olga; Hu, Yanle; Li, Hua; Rodriguez, Vivian; Wooten, H. Omar; Yang, Deshan; Zhao, Tianyu; Mutic, Sasa; Li, H. Harold

    2016-01-01

    Purpose: The clinical commissioning of IMRT subject to a magnetic field is challenging. The purpose of this work is to develop a GPU-accelerated Monte Carlo dose calculation platform based on penelope and then use the platform to validate a vendor-provided MRIdian head model toward quality assurance of clinical IMRT treatment plans subject to a 0.35 T magnetic field. Methods: penelope was first translated from fortran to c++ and the result was confirmed to produce equivalent results to the original code. The c++ code was then adapted to cuda in a workflow optimized for GPU architecture. The original code was expanded to include voxelized transport with Woodcock tracking, faster electron/positron propagation in a magnetic field, and several features that make gpenelope highly user-friendly. Moreover, the vendor-provided MRIdian head model was incorporated into the code in an effort to apply gpenelope as both an accurate and rapid dose validation system. A set of experimental measurements were performed on the MRIdian system to examine the accuracy of both the head model and gpenelope. Ultimately, gpenelope was applied toward independent validation of patient doses calculated by MRIdian’s kmc. Results: An acceleration factor of 152 was achieved in comparison to the original single-thread fortran implementation with the original accuracy being preserved. For 16 treatment plans including stomach (4), lung (2), liver (3), adrenal gland (2), pancreas (2), spleen(1), mediastinum (1), and breast (1), the MRIdian dose calculation engine agrees with gpenelope with a mean gamma passing rate of 99.1% ± 0.6% (2%/2 mm). Conclusions: A Monte Carlo simulation platform was developed based on a GPU- accelerated version of penelope. This platform was used to validate that both the vendor-provided head model and fast Monte Carlo engine used by the MRIdian system are accurate in modeling radiation transport in a patient using 2%/2 mm gamma criteria. Future applications of this

  12. A GPU-accelerated Monte Carlo dose calculation platform and its application toward validating an MRI-guided radiation therapy beam model.

    PubMed

    Wang, Yuhe; Mazur, Thomas R; Green, Olga; Hu, Yanle; Li, Hua; Rodriguez, Vivian; Wooten, H Omar; Yang, Deshan; Zhao, Tianyu; Mutic, Sasa; Li, H Harold

    2016-07-01

    The clinical commissioning of IMRT subject to a magnetic field is challenging. The purpose of this work is to develop a GPU-accelerated Monte Carlo dose calculation platform based on penelope and then use the platform to validate a vendor-provided MRIdian head model toward quality assurance of clinical IMRT treatment plans subject to a 0.35 T magnetic field. penelope was first translated from fortran to c++ and the result was confirmed to produce equivalent results to the original code. The c++ code was then adapted to cuda in a workflow optimized for GPU architecture. The original code was expanded to include voxelized transport with Woodcock tracking, faster electron/positron propagation in a magnetic field, and several features that make gpenelope highly user-friendly. Moreover, the vendor-provided MRIdian head model was incorporated into the code in an effort to apply gpenelope as both an accurate and rapid dose validation system. A set of experimental measurements were performed on the MRIdian system to examine the accuracy of both the head model and gpenelope. Ultimately, gpenelope was applied toward independent validation of patient doses calculated by MRIdian's kmc. An acceleration factor of 152 was achieved in comparison to the original single-thread fortran implementation with the original accuracy being preserved. For 16 treatment plans including stomach (4), lung (2), liver (3), adrenal gland (2), pancreas (2), spleen(1), mediastinum (1), and breast (1), the MRIdian dose calculation engine agrees with gpenelope with a mean gamma passing rate of 99.1% ± 0.6% (2%/2 mm). A Monte Carlo simulation platform was developed based on a GPU- accelerated version of penelope. This platform was used to validate that both the vendor-provided head model and fast Monte Carlo engine used by the MRIdian system are accurate in modeling radiation transport in a patient using 2%/2 mm gamma criteria. Future applications of this platform will include dose validation and

  13. Cardiac dose-sparing effects of deep-inspiration breath-hold in left breast irradiation : Is IMRT more beneficial than VMAT?

    PubMed

    Sakka, Mazen; Kunzelmann, Leonie; Metzger, Martin; Grabenbauer, Gerhard G

    2017-10-01

    Given the reduction in death from breast cancer, as well as improvements in overall survival, adjuvant radiotherapy is considered the standard treatment for breast cancer. However, left-sided breast irradiation was associated with an increased rate of fatal cardiovascular events due to incidental irradiation of the heart. Recently, considerable efforts have been made to minimize cardiac toxicity of left-sided breast irradiation by new treatment methods such as deep-inspiration breath-hold (DIBH) and new radiation techniques, particularly intensity modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT). The primary aim of this study was to evaluate the effect of DIBH irradiation on cardiac dose compared with free-breathing (FB) irradiation, while the secondary objective was to compare the advantages of IMRT versus VMAT plans in both the FB and the DIBH position for left-sided breast cancer. In all, 25 consecutive left-sided breast cancer patients underwent CT simulation in the FB and DIBH position. Five patients were excluded with no cardiac displacement following DIBH-CT simulation. The other 20 patients were irradiated in the DIBH position using respiratory gating. Four different treatment plans were generated for each patient, an IMRT and a VMAT plan in the DIBH and in the FB position, respectively. The following parameters were used for plan comparison: dose to the heart, left anterior descending coronary artery (mean dose, maximum dose, D25% and D45%), ipsilateral, contralateral lung (mean dose, D20%, D30%) and contralateral breast (mean dose). The percentage in dose reduction for organs at risk achieved by DIBH for both IMRT and VMAT plans was calculated and compared for each patient by each treatment plan. DIBH irradiation significantly reduced mean dose to the heart and left anterior descending coronary artery (LADCA) using both IMRT (heart -20%; p = 0.0002, LADCA -9%; p = 0.001) and VMAT (heart -23%; p = 0.00003, LADCA -16%; p = 0

  14. Monte Carlo-based QA for IMRT of head and neck cancers

    NASA Astrophysics Data System (ADS)

    Tang, F.; Sham, J.; Ma, C.-M.; Li, J.-S.

    2007-06-01

    It is well-known that the presence of large air cavity in a dense medium (or patient) introduces significant electronic disequilibrium when irradiated with megavoltage X-ray field. This condition may worsen by the possible use of tiny beamlets in intensity-modulated radiation therapy (IMRT). Commercial treatment planning systems (TPSs), in particular those based on the pencil-beam method, do not provide accurate dose computation for the lungs and other cavity-laden body sites such as the head and neck. In this paper we present the use of Monte Carlo (MC) technique for dose re-calculation of IMRT of head and neck cancers. In our clinic, a turn-key software system is set up for MC calculation and comparison with TPS-calculated treatment plans as part of the quality assurance (QA) programme for IMRT delivery. A set of 10 off-the-self PCs is employed as the MC calculation engine with treatment plan parameters imported from the TPS via a graphical user interface (GUI) which also provides a platform for launching remote MC simulation and subsequent dose comparison with the TPS. The TPS-segmented intensity maps are used as input for the simulation hence skipping the time-consuming simulation of the multi-leaf collimator (MLC). The primary objective of this approach is to assess the accuracy of the TPS calculations in the presence of air cavities in the head and neck whereas the accuracy of leaf segmentation is verified by fluence measurement using a fluoroscopic camera-based imaging device. This measurement can also validate the correct transfer of intensity maps to the record and verify system. Comparisons between TPS and MC calculations of 6 MV IMRT for typical head and neck treatments review regional consistency in dose distribution except at and around the sinuses where our pencil-beam-based TPS sometimes over-predicts the dose by up to 10%, depending on the size of the cavities. In addition, dose re-buildup of up to 4% is observed at the posterior nasopharyngeal

  15. SU-F-T-388: Comparison of Biophysical Indices in Hippocampal-Avoidance Whole Brain VMAT and IMRT Radiation Therapy Treatment Plans

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kendall, E; Ahmad, S; Algan, O

    2016-06-15

    Purpose: To compare biophysical indices of Volumetric Modulated Arc Therapy (VMAT) and Intensity Modulated Radiation Therapy (IMRT) treatment plans for whole brain radiation therapy following the NRG-CC001 protocol. Methods: In this retrospective study, a total of fifteen patients were planned with Varian Eclipse Treatment Planning System using VMAT (RapidArc) and IMRT techniques. The planning target volume (PTV) was defined as the whole brain volume excluding a uniform three-dimensional 5mm expansion of the hippocampus volume. Prescribed doses in all plans were 30 Gy delivered over 10 fractions normalized to a minimum of 95% of the target volume receiving 100% of themore » prescribed dose. The NRG Oncology protocol guidelines were followed for contouring and dose-volume constraints. A single radiation oncologist evaluated all treatment plans. Calculations of statistical significance were performed using Student’s paired t-test. Results: All VMAT and IMRT plans met the NRG-CC001 protocol dose-volume criteria. The average equivalent uniform dose (EUD) for the PTV for VMAT vs. IMRT was respectively (19.05±0.33 Gy vs. 19.38±0.47 Gy) for α/β of 2 Gy and (19.47±0.30 Gy vs. 19.84±0.42 Gy) for α/β of 10 Gy. For the PTV, the average mean and maximum doses were 2% and 5% lower in VMAT plans than in IMRT plans, respectively. The average EUD and the normal tissue complication probability (NTCP) for the hippocampus in VMAT vs. IMRT plans were (15.28±1.35 Gy vs. 15.65±0.99 Gy, p=0.18) and (0.305±0.012 Gy vs. 0.308±0.008 Gy, p=0.192), respectively. The average EUD and NTCP for the optic chiasm were both 2% higher in VMAT than in IMRT plans. Conclusion: Though statistically insignificant, VMAT plans indicate a lower hippocampus EUD than IMRT plans. Also, a small variation in NTCP was found between plans.« less

  16. SU-E-T-593: Outcomes and Toxicities From a Clinical Trial of APBI Using MERT+IMRT with the Same XMLC

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Jimenez-Ortega, E.; Ureba, A.; Barbeiro, A.R.

    2015-06-15

    Purpose: We present the results from a clinical trial of accelerated partial breast irradiation (APBI), using mixed modulated photon and electron beams (MERT+IMRT) with the same photon multileaf collimator (xMLC). Methods: Seven patients were enrolled in the first year of the APBI clinical trial. Patients were selected following the conditions included in the NSABP B-39/RTOG 0413 protocol. The targets and clinically relevant normal structures were contoured on the CT images following this protocol for APBI-EBRT. All treatments were delivered using combined modulated electron and photon beams by means of the same xMLC installed in a SIEMENS Primus linac, with amore » reduced SSD equal to 60 cm for electron beams. The plans were performed with a treatment planning system based on full Monte Carlo simulations, called CARMEN, developed by our group. Simultaneously, an alternative IMRT plan was calculated with the commercial TPS PINNACLE v8.0m (Philips), and both plans were compared. An ad-hoc breast phantom with semi-spherical geometry called NAOMI was designed for a specific QA protocol. Patients received a total dose of 38.5 Gy, delivered in 10 fractions over 5 consecutive days, with a twice-a-day hypofractionated schema.Follow-up visits during 2.5 years on average were repeated at 1 month post-treatment, every 3 months for the first year, and every 6 months for the second year. Toxicity was scored according to National Cancer Institute Common Terminology Criteria for Adverse Events (CTCAE version 3.0). Results: This APBI technique achieved high loco-regional control rates and showed low acute toxicity (grade 1 of CTCAE) and no toxicities from first month onwards. Photographic assessment of cosmesis showed skin excellent results. Conclusion: The clinical results achieved with MERT+IMRT by using the same xMLC are comparable or even better than those obtained with other APBI techniques, thanks to a software solution without any additional equipment or specific device.« less

  17. Verification of eye lens dose in IMRT by MOSFET measurement.

    PubMed

    Wang, Xuetao; Li, Guangjun; Zhao, Jianling; Song, Ying; Xiao, Jianghong; Bai, Sen

    2018-04-17

    The eye lens is recognized as one of the most radiosensitive structures in the human body. The widespread use of intensity-modulated radiotherapy (IMRT) complicates dose verification and necessitates high standards of dose computation. The purpose of this work was to assess the computed dose accuracy of eye lens through measurements using a metal-oxide-semiconductor field-effect transistor (MOSFET) dosimetry system. Sixteen clinical IMRT plans of head and neck patients were copied to an anthropomorphic head phantom. Measurements were performed using the MOSFET dosimetry system based on the head phantom. Two MOSFET detectors were imbedded in the eyes of the head phantom as the left and the right lens, covered by approximately 5-mm-thick paraffin wax. The measurement results were compared with the calculated values with a dose grid size of 1 mm. Sixteen IMRT plans were delivered, and 32 measured lens doses were obtained for analysis. The MOSFET dosimetry system can be used to verify the lens dose, and our measurements showed that the treatment planning system used in our clinic can provide adequate dose assessment in eye lenses. The average discrepancy between measurement and calculation was 6.7 ± 3.4%, and the largest discrepancy was 14.3%, which met the acceptability criterion set by the American Association of Physicists in Medicine Task Group 53 for external beam calculation for multileaf collimator-shaped fields in buildup regions. Copyright © 2018 American Association of Medical Dosimetrists. Published by Elsevier Inc. All rights reserved.

  18. Development of a four-axis moving phantom for patient-specific QA of surrogate signal-based tracking IMRT.

    PubMed

    Mukumoto, Nobutaka; Nakamura, Mitsuhiro; Yamada, Masahiro; Takahashi, Kunio; Akimoto, Mami; Miyabe, Yuki; Yokota, Kenji; Kaneko, Shuji; Nakamura, Akira; Itasaka, Satoshi; Matsuo, Yukinori; Mizowaki, Takashi; Kokubo, Masaki; Hiraoka, Masahiro

    2016-12-01

    The purposes of this study were two-fold: first, to develop a four-axis moving phantom for patient-specific quality assurance (QA) in surrogate signal-based dynamic tumor-tracking intensity-modulated radiotherapy (DTT-IMRT), and second, to evaluate the accuracy of the moving phantom and perform patient-specific dosimetric QA of the surrogate signal-based DTT-IMRT. The four-axis moving phantom comprised three orthogonal linear actuators for target motion and a fourth one for surrogate motion. The positional accuracy was verified using four laser displacement gauges under static conditions (±40 mm displacements along each axis) and moving conditions [eight regular sinusoidal and fourth-power-of-sinusoidal patterns with peak-to-peak motion ranges (H) of 10-80 mm and a breathing period (T) of 4 s, and three irregular respiratory patterns with H of 1.4-2.5 mm in the left-right, 7.7-11.6 mm in the superior-inferior, and 3.1-4.2 mm in the anterior-posterior directions for the target motion, and 4.8-14.5 mm in the anterior-posterior direction for the surrogate motion, and T of 3.9-4.9 s]. Furthermore, perpendicularity, defined as the vector angle between any two axes, was measured using an optical measurement system. The reproducibility of the uncertainties in DTT-IMRT was then evaluated. Respiratory motions from 20 patients acquired in advance were reproduced and compared three-dimensionally with the originals. Furthermore, patient-specific dosimetric QAs of DTT-IMRT were performed for ten pancreatic cancer patients. The doses delivered to Gafchromic films under tracking and moving conditions were compared with those delivered under static conditions without dose normalization. Positional errors of the moving phantom under static and moving conditions were within 0.05 mm. The perpendicularity of the moving phantom was within 0.2° of 90°. The differences in prediction errors between the original and reproduced respiratory motions were -0.1 ± 0.1 mm for the lateral

  19. Dosimetric benefits of IMRT and VMAT in the treatment of middle thoracic esophageal cancer: is the conformal radiotherapy still an alternative option?

    PubMed

    Wu, Zhiqin; Xie, Congying; Hu, Meilong; Han, Ce; Yi, Jinling; Zhou, Yongqiang; Yuan, Huawei; Jin, Xiance

    2014-05-08

    The purpose of this study is to investigate the dosimetric differences among conformal radiotherapy (CRT), intensity-modulated radiotherapy (IMRT), and volumetric-modulated radiotherapy (VMAT) in the treatment of middle thoracic esophageal cancer, and determine the most appropriate treatment modality. IMRT and one-arc VMAT plans were generated for eight middle thoracic esophageal cancer patients treated previous with CRT. The planning target volume (PTV) coverage and protections on organs at risk of three planning schemes were compared. All plans have sufficient PTV coverage and no significant differences were observed, except for the conformity and homogeneity. The lung V5, V10, and V13 in CRT were 47.9% ± 6.1%, 36.5% ± 4.6%, and 33.2% ± 4.2%, respectively, which were greatly increased to 78.2% ± 13.7% (p < 0.01), 80.8% ± 14.9% (p < 0.01), 48.4% ± 8.2% (p = 0.05) in IMRT and 58.6% ± 10.5% (p = 0.03), 67.7% ± 14.0% (p < 0.01), and 53.0% ± 10.1% (p < 0.01) in VMAT, respectively. The lung V20 (p = 0.03) in VMAT and the V30 (p = 0.04) in IMRT were lower than those in CRT. Both IMRT and VMAT achieved a better protection on heart. However, the volumes of the healthy tissue outside of PTV irradiated by a low dose were higher for IMRT and VMAT. IMRT and VMAT also had a higher MU, optimization time, and delivery time compared to CRT. In conclusion, all CRT, IMRT, and VMAT plans are able to meet the prescription and there is no clear distinction on PTV coverage. IMRT and VMAT can only decrease the volume of lung and heart receiving a high dose, but at a cost of delivering low dose to more volume of lung and normal tissues. CRT is still a feasible option for middle thoracic esophageal cancer radiotherapy, especially for the cost-effective consideration.

  20. A randomized phase II/III study of adverse events between sequential (SEQ) versus simultaneous integrated boost (SIB) intensity modulated radiation therapy (IMRT) in nasopharyngeal carcinoma; preliminary result on acute adverse events.

    PubMed

    Songthong, Anussara P; Kannarunimit, Danita; Chakkabat, Chakkapong; Lertbutsayanukul, Chawalit

    2015-08-08

    To investigate acute and late toxicities comparing sequential (SEQ-IMRT) versus simultaneous integrated boost intensity modulated radiotherapy (SIB-IMRT) in nasopharyngeal carcinoma (NPC) patients. Newly diagnosed stage I-IVB NPC patients were randomized to receive SEQ-IMRT or SIB-IMRT, with or without chemotherapy. SEQ-IMRT consisted of two sequential radiation treatment plans: 2 Gy x 25 fractions to low-risk planning target volume (PTV-LR) followed by 2 Gy x 10 fractions to high-risk planning target volume (PTV-HR). In contrast, SIB-IMRT consisted of only one treatment plan: 2.12 Gy and 1.7 Gy x 33 fractions to PTV-HR and PTV-LR, respectively. Toxicities were evaluated according to CTCAE version 4.0. Between October 2010 and November 2013, 122 eligible patients were randomized between SEQ-IMRT (54 patients) and SIB-IMRT (68 patients). With median follow-up time of 16.8 months, there was no significant difference in toxicities between the two IMRT techniques. During chemoradiation, the most common grade 3-5 acute toxicities were mucositis (15.4% vs 13.6%, SEQ vs SIB, p = 0.788) followed by dysphagia (9.6% vs 9.1%, p = 1.000) and xerostomia (9.6% vs 7.6%, p = 0.748). During the adjuvant chemotherapy period, 25.6% and 32.7% experienced grade 3 weight loss in SEQ-IMRT and SIB-IMRT (p = 0.459). One-year overall survival (OS) and progression-free survival (PFS) were 95.8% and 95.5% in SEQ-IMRT and 98% and 90.2% in SIB-IMRT, respectively (p = 0.472 for OS and 0.069 for PFS). This randomized, phase II/III trial comparing SIB-IMRT versus SEQ-IMRT in NPC showed no statistically significant difference between both IMRT techniques in terms of acute adverse events. Short-term tumor control and survival outcome were promising.

  1. A comparison between cobalt and linear accelerator-based treatment plans for conformal and intensity-modulated radiotherapy.

    PubMed

    Adams, E J; Warrington, A P

    2008-04-01

    The simplicity of cobalt units gives them the advantage of reduced maintenance, running costs and downtime when compared with linear accelerators. However, treatments carried out on such units are typically limited to simple techniques. This study has explored the use of cobalt beams for conformal and intensity-modulated radiotherapy (IMRT). Six patients, covering a range of treatment sites, were planned using both X-ray photons (6/10 MV) and cobalt-60 gamma rays (1.17 and 1.33 MeV). A range of conformal and IMRT techniques were considered, as appropriate. Conformal plans created using cobalt beams for small breast, meningioma and parotid cases were found to compare well with those created using X-ray photons. By using additional fields, acceptable conformal plans were also created for oesophagus and prostate cases. IMRT plans were found to be of comparable quality for meningioma, parotid and thyroid cases on the basis of dose-volume histogram analysis. We conclude that it is possible to plan high-quality radical radiotherapy treatments for cobalt units. A well-designed beam blocking/compensation system would be required to enable a practical and efficient alternative to multileaf collimator (MLC)-based linac treatments to be offered. If cobalt units were to have such features incorporated into them, they could offer considerable benefits to the radiotherapy community.

  2. AAA and AXB algorithms for the treatment of nasopharyngeal carcinoma using IMRT and RapidArc techniques.

    PubMed

    Kamaleldin, Maha; Elsherbini, Nader A; Elshemey, Wael M

    2017-09-27

    The aim of this study is to evaluate the impact of anisotropic analytical algorithm (AAA) and 2 reporting systems (AXB-D m and AXB-D w ) of Acuros XB algorithm (AXB) on clinical plans of nasopharyngeal patients using intensity-modulated radiotherapy (IMRT) and RapidArc (RA) techniques. Six plans of different algorithm-technique combinations are performed for 10 patients to calculate dose-volume histogram (DVH) physical parameters for planning target volumes (PTVs) and organs at risk (OARs). The number of monitor units (MUs) and calculation time are also determined. Good coverage is reported for all algorithm-technique combination plans without exceeding the tolerance for OARs. Regardless of the algorithm, RA plans persistently reported higher D 2% values for PTV-70. All IMRT plans reported higher number of MUs (especially with AXB) than did RA plans. AAA-IMRT produced the minimum calculation time of all plans. Major differences between the investigated algorithm-technique combinations are reported only for the number of MUs and calculation time parameters. In terms of these 2 parameters, it is recommended to employ AXB in calculating RA plans and AAA in calculating IMRT plans to achieve minimum calculation times at reduced number of MUs. Copyright © 2017 American Association of Medical Dosimetrists. Published by Elsevier Inc. All rights reserved.

  3. Dosimetric effects of patient rotational setup errors on prostate IMRT treatments

    NASA Astrophysics Data System (ADS)

    Fu, Weihua; Yang, Yong; Li, Xiang; Heron, Dwight E.; Saiful Huq, M.; Yue, Ning J.

    2006-10-01

    The purpose of this work is to determine dose delivery errors that could result from systematic rotational setup errors (ΔΦ) for prostate cancer patients treated with three-phase sequential boost IMRT. In order to implement this, different rotational setup errors around three Cartesian axes were simulated for five prostate patients and dosimetric indices, such as dose-volume histogram (DVH), tumour control probability (TCP), normal tissue complication probability (NTCP) and equivalent uniform dose (EUD), were employed to evaluate the corresponding dosimetric influences. Rotational setup errors were simulated by adjusting the gantry, collimator and horizontal couch angles of treatment beams and the dosimetric effects were evaluated by recomputing the dose distributions in the treatment planning system. Our results indicated that, for prostate cancer treatment with the three-phase sequential boost IMRT technique, the rotational setup errors do not have significant dosimetric impacts on the cumulative plan. Even in the worst-case scenario with ΔΦ = 3°, the prostate EUD varied within 1.5% and TCP decreased about 1%. For seminal vesicle, slightly larger influences were observed. However, EUD and TCP changes were still within 2%. The influence on sensitive structures, such as rectum and bladder, is also negligible. This study demonstrates that the rotational setup error degrades the dosimetric coverage of target volume in prostate cancer treatment to a certain degree. However, the degradation was not significant for the three-phase sequential boost prostate IMRT technique and for the margin sizes used in our institution.

  4. In vivo and phantom measurements of the secondary photon and neutron doses for prostate patients undergoing 18 MV IMRT.

    PubMed

    Reft, Chester S; Runkel-Muller, Renate; Myrianthopoulos, Leon

    2006-10-01

    For intensity modulated radiation therapy (IMRT) treatments 6 MV photons are typically used, however, for deep seated tumors in the pelvic region, higher photon energies are increasingly being employed. IMRT treatments require more monitor units (MU) to deliver the same dose as conformal treatments, causing increased secondary radiation to tissues outside the treated area from leakage and scatter, as well as a possible increase in the neutron dose from photon interactions in the machine head. Here we provide in vivo patient and phantom measurements of the secondary out-of-field photon radiation and the neutron dose equivalent for 18 MV IMRT treatments. The patients were treated for prostate cancer with 18 MV IMRT at institutions using different therapy machines and treatment planning systems. Phantom exposures at the different facilities were used to compare the secondary photon and neutron dose equivalent between typical IMRT delivered treatment plans with a six field three-dimensional conformal radiotherapy (3DCRT) plan. For the in vivo measurements LiF thermoluminescent detectors (TLDs) and Al2O3 detectors using optically stimulated radiation were used to obtain the photon dose and CR-39 track etch detectors were used to obtain the neutron dose equivalent. For the phantom measurements a Bonner sphere (25.4 cm diameter) containing two types of TLDs (TLD-600 and TLD-700) having different thermal neutron sensitivities were used to obtain the out-of-field neutron dose equivalent. Our results showed that for patients treated with 18 MV IMRT the photon dose equivalent is greater than the neutron dose equivalent measured outside the treatment field and the neutron dose equivalent normalized to the prescription dose varied from 2 to 6 mSv/Gy among the therapy machines. The Bonner sphere results showed that the ratio of neutron equivalent doses for the 18 MV IMRT and 3DCRT prostate treatments scaled as the ratio of delivered MUs. We also observed differences in the

  5. A system for EPID-based real-time treatment delivery verification during dynamic IMRT treatment.

    PubMed

    Fuangrod, Todsaporn; Woodruff, Henry C; van Uytven, Eric; McCurdy, Boyd M C; Kuncic, Zdenka; O'Connor, Daryl J; Greer, Peter B

    2013-09-01

    To design and develop a real-time electronic portal imaging device (EPID)-based delivery verification system for dynamic intensity modulated radiation therapy (IMRT) which enables detection of gross treatment delivery errors before delivery of substantial radiation to the patient. The system utilizes a comprehensive physics-based model to generate a series of predicted transit EPID image frames as a reference dataset and compares these to measured EPID frames acquired during treatment. The two datasets are using MLC aperture comparison and cumulative signal checking techniques. The system operation in real-time was simulated offline using previously acquired images for 19 IMRT patient deliveries with both frame-by-frame comparison and cumulative frame comparison. Simulated error case studies were used to demonstrate the system sensitivity and performance. The accuracy of the synchronization method was shown to agree within two control points which corresponds to approximately ∼1% of the total MU to be delivered for dynamic IMRT. The system achieved mean real-time gamma results for frame-by-frame analysis of 86.6% and 89.0% for 3%, 3 mm and 4%, 4 mm criteria, respectively, and 97.9% and 98.6% for cumulative gamma analysis. The system can detect a 10% MU error using 3%, 3 mm criteria within approximately 10 s. The EPID-based real-time delivery verification system successfully detected simulated gross errors introduced into patient plan deliveries in near real-time (within 0.1 s). A real-time radiation delivery verification system for dynamic IMRT has been demonstrated that is designed to prevent major mistreatments in modern radiation therapy.

  6. IMRT and 3D conformal radiotherapy with or without elective nodal irradiation in locally advanced NSCLC: A direct comparison of PET-based treatment planning.

    PubMed

    Fleckenstein, Jochen; Kremp, Katharina; Kremp, Stephanie; Palm, Jan; Rübe, Christian

    2016-02-01

    The potential of intensity-modulated radiation therapy (IMRT) as opposed to three-dimensional conformal radiotherapy (3D-CRT) is analyzed for two different concepts of fluorodeoxyglucose positron emission tomography (FDG PET)-based target volume delineation in locally advanced non-small cell lung cancer (LA-NSCLC): involved-field radiotherapy (IF-RT) vs. elective nodal irradiation (ENI). Treatment planning was performed for 41 patients with LA-NSCLC, using four different planning approaches (3D-CRT-IF, 3D-CRT-ENI, IMRT-IF, IMRT-ENI). ENI included a boost irradiation after 50 Gy. For each plan, maximum dose escalation was calculated based on prespecified normal tissue constraints. The maximum prescription dose (PD), tumor control probability (TCP), conformal indices (CI), and normal tissue complication probabilities (NTCP) were analyzed. IMRT resulted in statistically significant higher prescription doses for both target volume concepts as compared with 3D-CRT (ENI: 68.4 vs. 60.9 Gy, p < 0.001; IF: 74.3 vs. 70.1 Gy, p < 0.03). With IMRT-IF, a PD of at least 66 Gy was achieved for 95 % of all plans. For IF as compared with ENI, there was a considerable theoretical increase in TCP (IMRT: 27.3 vs. 17.7 %, p < 0.00001; 3D-CRT: 20.2 vs. 9.9 %, p < 0.00001). The esophageal NTCP showed a particularly good sparing with IMRT vs. 3D-CRT (ENI: 12.3 vs. 30.9 % p < 0.0001; IF: 15.9 vs. 24.1 %; p < 0.001). The IMRT technique and IF target volume delineation allow a significant dose escalation and an increase in TCP. IMRT results in an improved sparing of OARs as compared with 3D-CRT at equivalent dose levels.

  7. SU-E-T-393: Evaluation of Large Field IMRT Versus RapidArc Planning for Carcinoma Cervix with Para-Aotic Node Irradiation

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Raman, S Kothanda; Girigesh, Y; MISHRA, M

    Purpose: The objective of this work is to evaluate and compare Large field IMRT and RapidArc planning for Carcinoma Cervix and Para-aotic node irradiation. Methods: In this study, ten patients of Cervix with para-aotic node have been selected with PTV length 35+2cm. All plans were generated in Eclipse TPS V10.0 with Dynamic IMRT and RapidArc technique using 6MV photon energy. In IMRT planning, 7 fields were chosen to get optimal plan and in RapidArc, double Full arc clockwise and counter clockwise were used for planning. All the plans were generated with single isocenter and calculated using AAA dose algorithm. Formore » all the cases the prescribed dose to PTV was same and the plan acceptance criteria is; 95% of the PTV volume should receive 100% prescribed dose. The tolerance doses for the OAR’s is also taken in to account. The evaluation criteria used for analysis are; 1) Homogeneity Index, 2) Conformity Index, 3) Mean Dose to OAR’s, 4)Total monitor units delivered. Results: DVH analysis were performed for both IMRT and RapidArc planning. In both the plans, 95% of PTV volume receives prescribed dose and maximum dose are less than 107%. The conformity index are same in both the techniques. The mean Homogeneity index are 1.036 and 1.053 for IMRT and RapidArc plan. The mean (mean + SD) dose of bladder and rectum in IMRT is 44.2+1.55, 42.05+2.52 and RapidArc is 46.66+1.6, 44.2+2.75 respectively. There is no significant difference found in Right Femoral head, Left Femoral head and Kidney doses. It is found that total MU’s are more in IMRT compared with RapidArc planning. Conclusion: In the case of cervix with Para-arotic node single isocenter irradiation, IMRT planning in large-field is better compared to RapidArc planning in terms of Homogeneity Index and mean dose of Bladder and Rectum.« less

  8. A new plan quality index for nasopharyngeal cancer SIB IMRT.

    PubMed

    Jin, X; Yi, J; Zhou, Y; Yan, H; Han, C; Xie, C

    2014-02-01

    A new plan quality index integrating dosimetric and radiobiological indices was proposed to facilitate the evaluation and comparison of simultaneous integrated boost (SIB) intensity modulated radiotherapy (IMRT) plans for nasopharyngeal cancer (NPC) patients. Ten NPC patients treated by SIB-IMRT were enrolled in the study. Custom software was developed to read dose-volume histogram (DVH) curves from the treatment planning system (TPS). A plan filtering matrix was introduced to filter plans that fail to satisfy treatment protocol. Target plan quality indices and organ at risk (OAR) plan quality indices were calculated for qualified plans. A unique composite plan quality index (CPQI) was proposed based on the relative weight of these indices to evaluate and compare competing plans. Plan ranking results were compared with detailed statistical analysis, radiation oncology quality system (ROQS) scoring results and physician's evaluation results to verify the accuracy of this new plan quality index. The average CPQI values for plans with OAR priority of low, normal, high, and PTV only were 0.22 ± 0.08, 0.49 ± 0.077, 0.71 ± 0.062, and -0.21 ± 0.16, respectively. There were significant differences among these plan quality indices (One-way ANOVA test, p < 0.01). This was consistent with statistical analysis, ROQS results and physician's ranking results in which 90% OAR high plans were selected. Plan filtering matrix was able to speed up the plan evaluation process. The new matrix plan quality index CPQI showed good consistence with physician ranking results. It is a promising index for NPC SIB-IMRT plan evaluation. Copyright © 2013 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  9. Evaluation of dose coverage to target volume and normal tissue sparing in the adjuvant radiotherapy of gastric cancers: 3D-CRT compared with dynamic IMRT.

    PubMed

    Murthy, Kk; Shukeili, Ka; Kumar, Ss; Davis, Ca; Chandran, Rr; Namrata, S

    2010-01-01

    To assess the potential advantage of intensity-modulated radiotherapy (IMRT) over 3D-conformal radiotherapy (3D-CRT) planning in postoperative adjuvant radiotherapy for patients with gastric carcinoma. In a retrospective study, for plan comparison, dose distribution was recalculated in 15 patients treated with 3D-CRT on the contoured structures of same CT images using an IMRT technique. 3D-conformal plans with three fields and four-fields were compared with seven-field dynamic IMRT plans. The different plans were compared by analyzing the dose coverage of planning target volume using TV(95), D(mean), uniformity index, conformity index and homogeneity index parameters. To assess critical organ sparing, D(mean), D(max), dose to one-third and two-third volumes of the OARs and percentage of volumes receiving more than their tolerance doses were compared. The average dose coverage values of PTV with 3F-CRT and 4F-CRT plans were comparable, where as IMRT plans achieved better target coverage(p<0.001) with higher conformity index value of 0.81±0.07 compared to both the 3D-CRT plans. The doses to the liver and bowel reduced significantly (p<0.001) with IMRT plans compared to other 3D-CRT plans. For all OARs the percentage of volumes receiving more than their tolerance doses were reduced with the IMRT plans. This study showed that a better target coverage and significant dose reduction to OARs could be achieved with the IMRT plans. The IMRT can be preferred with caution for organ motion. The authors are currently studying organ motion in the upper abdomen to use IMRT for patient treatment.

  10. Sensitivity in error detection of patient specific QA tools for IMRT plans

    NASA Astrophysics Data System (ADS)

    Lat, S. Z.; Suriyapee, S.; Sanghangthum, T.

    2016-03-01

    The high complexity of dose calculation in treatment planning and accurate delivery of IMRT plan need high precision of verification method. The purpose of this study is to investigate error detection capability of patient specific QA tools for IMRT plans. The two H&N and two prostate IMRT plans with MapCHECK2 and portal dosimetry QA tools were studied. Measurements were undertaken for original and modified plans with errors introduced. The intentional errors composed of prescribed dose (±2 to ±6%) and position shifting in X-axis and Y-axis (±1 to ±5mm). After measurement, gamma pass between original and modified plans were compared. The average gamma pass for original H&N and prostate plans were 98.3% and 100% for MapCHECK2 and 95.9% and 99.8% for portal dosimetry, respectively. In H&N plan, MapCHECK2 can detect position shift errors starting from 3mm while portal dosimetry can detect errors started from 2mm. Both devices showed similar sensitivity in detection of position shift error in prostate plan. For H&N plan, MapCHECK2 can detect dose errors starting at ±4%, whereas portal dosimetry can detect from ±2%. For prostate plan, both devices can identify dose errors starting from ±4%. Sensitivity of error detection depends on type of errors and plan complexity.

  11. On the performances of different IMRT Treatment Planning Systems for selected paediatric cases.

    PubMed

    Fogliata, Antonella; Nicolini, Giorgia; Alber, Markus; Asell, Mats; Clivio, Alessandro; Dobler, Barbara; Larsson, Malin; Lohr, Frank; Lorenz, Friedlieb; Muzik, Jan; Polednik, Martin; Vanetti, Eugenio; Wolff, Dirk; Wyttenbach, Rolf; Cozzi, Luca

    2007-02-15

    To evaluate the performance of seven different TPS (Treatment Planning Systems: Corvus, Eclipse, Hyperion, KonRad, Oncentra Masterplan, Pinnacle and PrecisePLAN) when intensity modulated (IMRT) plans are designed for paediatric tumours. Datasets (CT images and volumes of interest) of four patients were used to design IMRT plans. The tumour types were: one extraosseous, intrathoracic Ewing Sarcoma; one mediastinal Rhabdomyosarcoma; one metastatic Rhabdomyosarcoma of the anus; one Wilm's tumour of the left kidney with multiple liver metastases. Prescribed doses ranged from 18 to 54.4 Gy. To minimise variability, the same beam geometry and clinical goals were imposed on all systems for every patient. Results were analysed in terms of dose distributions and dose volume histograms. For all patients, IMRT plans lead to acceptable treatments in terms of conformal avoidance since most of the dose objectives for Organs At Risk (OARs) were met, and the Conformity Index (averaged over all TPS and patients) ranged from 1.14 to 1.58 on primary target volumes and from 1.07 to 1.37 on boost volumes. The healthy tissue involvement was measured in terms of several parameters, and the average mean dose ranged from 4.6 to 13.7 Gy. A global scoring method was developed to evaluate plans according to their degree of success in meeting dose objectives (lower scores are better than higher ones). For OARs the range of scores was between 0.75 +/- 0.15 (Eclipse) to 0.92 +/- 0.18 (Pinnacle(3) with physical optimisation). For target volumes, the score ranged from 0.05 +/- 0.05 (Pinnacle(3) with physical optimisation) to 0.16 +/- 0.07 (Corvus). A set of complex paediatric cases presented a variety of individual treatment planning challenges. Despite the large spread of results, inverse planning systems offer promising results for IMRT delivery, hence widening the treatment strategies for this very sensitive class of patients.

  12. Image-guided, intensity-modulated radiation therapy (IG-IMRT) for skull base chordoma and chondrosarcoma: preliminary outcomes.

    PubMed

    Sahgal, Arjun; Chan, Michael W; Atenafu, Eshetu G; Masson-Cote, Laurence; Bahl, Gaurav; Yu, Eugene; Millar, Barbara-Ann; Chung, Caroline; Catton, Charles; O'Sullivan, Brian; Irish, Jonathan C; Gilbert, Ralph; Zadeh, Gelareh; Cusimano, Michael; Gentili, Fred; Laperriere, Normand J

    2015-06-01

    We report our preliminary outcomes following high-dose image-guided intensity modulated radiotherapy (IG-IMRT) for skull base chordoma and chondrosarcoma. Forty-two consecutive IG-IMRT patients, with either skull base chordoma (n = 24) or chondrosarcoma (n = 18) treated between August 2001 and December 2012 were reviewed. The median follow-up was 36 months (range, 3-90 mo) in the chordoma cohort, and 67 months (range, 15-125) in the chondrosarcoma cohort. Initial surgery included biopsy (7% of patients), subtotal resection (57% of patients), and gross total resection (36% of patients). The median IG-IMRT total doses in the chondrosarcoma and chordoma cohorts were 70 Gy and 76 Gy, respectively, delivered with 2 Gy/fraction. For the chordoma and chondrosarcoma cohorts, the 5-year overall survival and local control rates were 85.6% and 65.3%, and 87.8% and 88.1%, respectively. In total, 10 patients progressed locally: 8 were chordoma patients and 2 chondrosarcoma patients. Both chondrosarcoma failures were in higher-grade tumors (grades 2 and 3). None of the 8 patients with grade 1 chondrosarcoma failed, with a median follow-up of 77 months (range, 34-125). There were 8 radiation-induced late effects-the most significant was a radiation-induced secondary malignancy occurring 6.7 years following IG-IMRT. Gross total resection and age were predictors of local control in the chordoma and chondrosarcoma patients, respectively. We report favorable survival, local control and adverse event rates following high dose IG-IMRT. Further follow-up is needed to confirm long-term efficacy. © The Author(s) 2014. Published by Oxford University Press on behalf of the Society for Neuro-Oncology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  13. Multi-Case Knowledge-Based IMRT Treatment Planning in Head and Neck Cancer

    NASA Astrophysics Data System (ADS)

    Grzetic, Shelby Mariah

    Head and neck cancer (HNC) IMRT treatment planning is a challenging process that relies heavily on the planner's experience. Previously, we used the single, best match from a library of manually planned cases to semi-automatically generate IMRT plans for a new patient. The current multi-case Knowledge Based Radiation Therapy (MC-KBRT) study utilized different matching cases for each of six individual organs-at-risk (OARs), then combined those six cases to create the new treatment plan. From a database of 103 patient plans created by experienced planners, MC-KBRT plans were created for 40 (17 unilateral and 23 bilateral) HNC "query" patients. For each case, 2D beam's-eye-view images were used to find similar geometric "match" patients separately for each of 6 OARs. Dose distributions for each OAR from the 6 matching cases were combined and then warped to suit the query case's geometry. The dose-volume constraints were used to create the new query treatment plan without the need for human decision-making throughout the IMRT optimization. The optimized MC-KBRT plans were compared against the clinically approved plans and Version 1 (previous KBRT using only one matching case with dose warping) using the dose metrics: mean, median, and maximum (brainstem and cord+5mm) doses. Compared to Version 1, MC-KBRT had no significant reduction of the dose to any of the OARs in either unilateral or bilateral cases. Compared to the manually planned unilateral cases, there was significant reduction of the oral cavity mean/median dose (>2Gy) at the expense of the contralateral parotid. Compared to the manually planned bilateral cases, reduction of dose was significant in the ipsilateral parotid, larynx, and oral cavity (>3Gy mean/median) while maintaining PTV coverage. MC-KBRT planning in head and neck cancer generates IMRT plans with better dose sparing than manually created plans. MC-KBRT using multiple case matches does not show significant dose reduction compared to using a

  14. SU-F-T-356: DosimetricComparison of VMAT Vs Step and Shoot IMRT Plans for Stage III Lung CancerPatients with Mediastinal Involvement

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Pearson, D; Bogue, J

    Purpose: For Stage III lung cancers that entail treatment of some or all of the mediastinum, anterior-posterior focused Step and Shoot IMRT (SS-IMRT) and VMAT plans have been clinically used to deliver the prescribed dose while working to minimize lung dose and avoid other critical structures. A comparison between the two planning methods was completed to see which treatment method is superior and minimizes dose to healthy lung tissue. Methods: Ten patients who were recently treated with SS-IMRT or VMAT plans for Stage III lung cancer with mediastinal involvement were selected. All patients received a simulation CT for treatment planning,more » as well as a 4D CT and PET/CT fusion for target delineation. Plans were prescribed 6250 cGy in 25 fractions and normalized such that 100% of the prescription dose covered 95% of the PTV. Clinically approved SS-IMRT or VMAT plans were then copied and planned using the alternative modality with identical optimization criteria. SS-IMRT plans utilized seven to nine beams distributed around the patient while the VMAT plans consisted of two full 360 degree arcs. Plans were compared for the lung volume receiving 20 Gy (V20). Results: Both SS-IMRT and VMAT can be used to achieve clinical treatment plans for patients with Stage III Lung cancer with targets encompassing the mediastinum. VMAT plans produced an average V20 of 23.0+/−8.3% and SS-IMRT produced an average of 24.2+/−10.0%. Conclusion: Results indicate that either method can achieve comparable dose distributions, however, VMAT can allow the optimizer to distribute dose over paths of minimal lung tissue and reduce the V20. Therefore, creating a VMAT with constraints identical to an SS-IMRT plan could help to reduce the V20 in clinical treatment plans.« less

  15. A novel approach to EPID-based 3D volumetric dosimetry for IMRT and VMAT QA

    NASA Astrophysics Data System (ADS)

    Alhazmi, Abdulaziz; Gianoli, Chiara; Neppl, Sebastian; Martins, Juliana; Veloza, Stella; Podesta, Mark; Verhaegen, Frank; Reiner, Michael; Belka, Claus; Parodi, Katia

    2018-06-01

    Intensity modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) are relatively complex treatment delivery techniques and require quality assurance (QA) procedures. Pre-treatment dosimetric verification represents a fundamental QA procedure in daily clinical routine in radiation therapy. The purpose of this study is to develop an EPID-based approach to reconstruct a 3D dose distribution as imparted to a virtual cylindrical water phantom to be used for plan-specific pre-treatment dosimetric verification for IMRT and VMAT plans. For each depth, the planar 2D dose distributions acquired in air were back-projected and convolved by depth-specific scatter and attenuation kernels. The kernels were obtained by making use of scatter and attenuation models to iteratively estimate the parameters from a set of reference measurements. The derived parameters served as a look-up table for reconstruction of arbitrary measurements. The summation of the reconstructed 3D dose distributions resulted in the integrated 3D dose distribution of the treatment delivery. The accuracy of the proposed approach was validated in clinical IMRT and VMAT plans by means of gamma evaluation, comparing the reconstructed 3D dose distributions with Octavius measurement. The comparison was carried out using (3%, 3 mm) criteria scoring 99% and 96% passing rates for IMRT and VMAT, respectively. An accuracy comparable to the one of the commercial device for 3D volumetric dosimetry was demonstrated. In addition, five IMRT and five VMAT were validated against the 3D dose calculation performed by the TPS in a water phantom using the same passing rate criteria. The median passing rates within the ten treatment plans was 97.3%, whereas the lowest was 95%. Besides, the reconstructed 3D distribution is obtained without predictions relying on forward dose calculation and without external phantom or dosimetric devices. Thus, the approach provides a fully automated, fast and easy QA

  16. Volumetric modulated arc therapy vs. c-IMRT for the treatment of upper thoracic esophageal cancer.

    PubMed

    Zhang, Wu-Zhe; Zhai, Tian-Tian; Lu, Jia-Yang; Chen, Jian-Zhou; Chen, Zhi-Jian; Li, De-Rui; Chen, Chuang-Zhen

    2015-01-01

    To compare plans using volumetric-modulated arc therapy (VMAT) with conventional sliding window intensity-modulated radiation therapy (c-IMRT) to treat upper thoracic esophageal cancer (EC). CT datasets of 11 patients with upper thoracic EC were identified. Four plans were generated for each patient: c-IMRT with 5 fields (5F) and VMAT with a single arc (1A), two arcs (2A), or three arcs (3A). The prescribed doses were 64 Gy/32 F for the primary tumor (PTV64). The dose-volume histogram data, the number of monitoring units (MUs) and the treatment time (TT) for the different plans were compared. All of the plans generated similar dose distributions for PTVs and organs at risk (OARs), except that the 2A- and 3A-VMAT plans yielded a significantly higher conformity index (CI) than the c-IMRT plan. The CI of the PTV64 was improved by increasing the number of arcs in the VMAT plans. The maximum spinal cord dose and the planning risk volume of the spinal cord dose for the two techniques were similar. The 2A- and 3A-VMAT plans yielded lower mean lung doses and heart V50 values than the c-IMRT. The V20 and V30 for the lungs in all of the VMAT plans were lower than those in the c-IMRT plan, at the expense of increasing V5, V10 and V13. The VMAT plan resulted in significant reductions in MUs and TT. The 2A-VMAT plan appeared to spare the lungs from moderate-dose irradiation most effectively of all plans, at the expense of increasing the low-dose irradiation volume, and also significantly reduced the number of required MUs and the TT. The CI of the PTVs and the OARs was improved by increasing the arc-number from 1 to 2; however, no significant improvement was observed using the 3A-VMAT, except for an increase in the TT.

  17. Volumetric Modulated Arc Therapy vs. c-IMRT for the Treatment of Upper Thoracic Esophageal Cancer

    PubMed Central

    Lu, Jia-Yang; Chen, Jian-Zhou; Chen, Zhi-Jian; Li, De-Rui; Chen, Chuang-Zhen

    2015-01-01

    Objective To compare plans using volumetric-modulated arc therapy (VMAT) with conventional sliding window intensity-modulated radiation therapy (c-IMRT) to treat upper thoracic esophageal cancer (EC). Methods CT datasets of 11 patients with upper thoracic EC were identified. Four plans were generated for each patient: c-IMRT with 5 fields (5F) and VMAT with a single arc (1A), two arcs (2A), or three arcs (3A). The prescribed doses were 64 Gy/32 F for the primary tumor (PTV64). The dose-volume histogram data, the number of monitoring units (MUs) and the treatment time (TT) for the different plans were compared. Results All of the plans generated similar dose distributions for PTVs and organs at risk (OARs), except that the 2A- and 3A-VMAT plans yielded a significantly higher conformity index (CI) than the c-IMRT plan. The CI of the PTV64 was improved by increasing the number of arcs in the VMAT plans. The maximum spinal cord dose and the planning risk volume of the spinal cord dose for the two techniques were similar. The 2A- and 3A-VMAT plans yielded lower mean lung doses and heart V50 values than the c-IMRT. The V20 and V30 for the lungs in all of the VMAT plans were lower than those in the c-IMRT plan, at the expense of increasing V5, V10 and V13. The VMAT plan resulted in significant reductions in MUs and TT. Conclusion The 2A-VMAT plan appeared to spare the lungs from moderate-dose irradiation most effectively of all plans, at the expense of increasing the low-dose irradiation volume, and also significantly reduced the number of required MUs and the TT. The CI of the PTVs and the OARs was improved by increasing the arc-number from 1 to 2; however, no significant improvement was observed using the 3A-VMAT, except for an increase in the TT. PMID:25815477

  18. Improving IMRT delivery efficiency with reweighted L1-minimization for inverse planning

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kim, Hojin; Becker, Stephen; Lee, Rena

    2013-07-15

    Purpose: This study presents an improved technique to further simplify the fluence-map in intensity modulated radiation therapy (IMRT) inverse planning, thereby reducing plan complexity and improving delivery efficiency, while maintaining the plan quality.Methods: First-order total-variation (TV) minimization (min.) based on L1-norm has been proposed to reduce the complexity of fluence-map in IMRT by generating sparse fluence-map variations. However, with stronger dose sparing to the critical structures, the inevitable increase in the fluence-map complexity can lead to inefficient dose delivery. Theoretically, L0-min. is the ideal solution for the sparse signal recovery problem, yet practically intractable due to its nonconvexity of themore » objective function. As an alternative, the authors use the iteratively reweighted L1-min. technique to incorporate the benefits of the L0-norm into the tractability of L1-min. The weight multiplied to each element is inversely related to the magnitude of the corresponding element, which is iteratively updated by the reweighting process. The proposed penalizing process combined with TV min. further improves sparsity in the fluence-map variations, hence ultimately enhancing the delivery efficiency. To validate the proposed method, this work compares three treatment plans obtained from quadratic min. (generally used in clinic IMRT), conventional TV min., and our proposed reweighted TV min. techniques, implemented by a large-scale L1-solver (template for first-order conic solver), for five patient clinical data. Criteria such as conformation number (CN), modulation index (MI), and estimated treatment time are employed to assess the relationship between the plan quality and delivery efficiency.Results: The proposed method yields simpler fluence-maps than the quadratic and conventional TV based techniques. To attain a given CN and dose sparing to the critical organs for 5 clinical cases, the proposed method reduces the number of

  19. SU-E-J-81: Adaptive Radiotherapy for IMRT Head & Neck Patient in AKUH

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Yousuf, A; Qureshi, B; Qadir, A

    2015-06-15

    Purpose: In this study we proposed Adaptive radiotherapy for IMRT patients which will brought an additional dimension to the management of patients with H&N cancer in Aga Khan University Hospital. Methods: In this study 5 Head and Neck (H&N) patients plan where selected, who’s Re-CT were done during the course of their treatment, they were simulated with IMRT technique to learn the consequence of anatomical changes that may occur during the treatment, as they are more dramatic changes can occur as compare to conventional treatment. All the organ at risk were drawn according RTOG guidelines and doses were checked asmore » per NCCN guidelines. Results: The reduction in size of Planning target volume (PTV) is more than 20% in all the cases which leads to 3 to 5 % overdose to normal tissues and Organ at Risk. Conclusion: Through this study we would like to emphasis the importance of Adaptive Radiotherapy practice in all IMRT (H&N) patients, although prospective studies are required with larger sample sizes to address the safety and the clinical effect of such approaches on patient outcome, also one need to develop protocols before implementation of this technique in practice.« less

  20. Coverage-based constraints for IMRT optimization

    NASA Astrophysics Data System (ADS)

    Mescher, H.; Ulrich, S.; Bangert, M.

    2017-09-01

    Radiation therapy treatment planning requires an incorporation of uncertainties in order to guarantee an adequate irradiation of the tumor volumes. In current clinical practice, uncertainties are accounted for implicitly with an expansion of the target volume according to generic margin recipes. Alternatively, it is possible to account for uncertainties by explicit minimization of objectives that describe worst-case treatment scenarios, the expectation value of the treatment or the coverage probability of the target volumes during treatment planning. In this note we show that approaches relying on objectives to induce a specific coverage of the clinical target volumes are inevitably sensitive to variation of the relative weighting of the objectives. To address this issue, we introduce coverage-based constraints for intensity-modulated radiation therapy (IMRT) treatment planning. Our implementation follows the concept of coverage-optimized planning that considers explicit error scenarios to calculate and optimize patient-specific probabilities q(\\hat{d}, \\hat{v}) of covering a specific target volume fraction \\hat{v} with a certain dose \\hat{d} . Using a constraint-based reformulation of coverage-based objectives we eliminate the trade-off between coverage and competing objectives during treatment planning. In-depth convergence tests including 324 treatment plan optimizations demonstrate the reliability of coverage-based constraints for varying levels of probability, dose and volume. General clinical applicability of coverage-based constraints is demonstrated for two cases. A sensitivity analysis regarding penalty variations within this planing study based on IMRT treatment planning using (1) coverage-based constraints, (2) coverage-based objectives, (3) probabilistic optimization, (4) robust optimization and (5) conventional margins illustrates the potential benefit of coverage-based constraints that do not require tedious adjustment of target volume objectives.

  1. IMRT vs. 3D Noncoplanar Treatment Plans for Maxillary Sinus Tumors: A New Tool for Quantitative Evaluation

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Levin, Daphne; Menhel, Janna; Alezra, Dror

    2008-01-01

    We compared 9-field, equispaced intensity modulated radiation therapy (IMRT), 4- to 5-field, directionally optimized IMRT, and 3-dimensional (3D) noncoplanar planning approaches for tumors of the maxillary sinus. Ten patients were planned retrospectively to compare the different treatment techniques. Prescription doses were 60 to 70 Gy. Critical structures contoured included optic nerves and chiasm, lacrimal glands, lenses, and retinas. As an aid for plan assessment, we introduced a new tool: Critical Organ Scoring Index (COSI), which allows quantitative evaluation of the tradeoffs between target coverage and critical organ sparing. This index was compared with other, commonly used conformity indices. For amore » reliable assessment of both tumor coverage and dose to critical organs in the different planning techniques, we introduced a 2D, graphical representation of COSI vs. conformity index (CI). Dose-volume histograms and mean, maximum, and minimum organ doses were also compared. IMRT plans delivered lower doses to ipsilateral structures, but were unable to spare them. 3D plans delivered less dose to contralateral structures, and were more homogeneous, as well. Both IMRT approaches gave similar results. In cases where choice of optimal plan was difficult, the novel 2D COSI-CI representation gave an accurate picture of the tradeoffs between target coverage and organ sparing, even in cases where other conformity indices failed. Due to their unique anatomy, maxillary sinus tumors may benefit more from a noncoplanar approach than from IMRT. The new graphical representation proposed is a quick, visual, reliable tool, which may facilitate the physician's choice of best treatment plan for a given patient.« less

  2. Evaluations of secondary cancer risk in spine radiotherapy using 3DCRT, IMRT, and VMAT: A phantom study

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Rehman, Jalil ur, E-mail: jalil_khanphy@yahoo.com; Department of Radiation Physics, UT MD Anderson Cancer Center, Houston, TX; Tailor, Ramesh C.

    2015-04-01

    This study evaluated the secondary cancer risk from volumetric-modulated arc therapy (VMAT) for spine radiotherapy compared with intensity-modulated radiotherapy (IMRT) and 3-dimensional conformal radiotherapy (3DCRT). Computed tomography images of an Radiological Physics Center spine anthropomorphic phantom were exported to a treatment planning system (Pinnacle{sup 3}, version 9.4). Radiation treatment plans for spine were prepared using VMAT (dual-arc), 7-field IMRT (beam angles: 110°, 130°, 150°, 180°, 210°, 230°, and 250°), and 4-field 3DCRT technique. The mean and maximum doses, dose-volume histograms, and volumes receiving more than 2 and 4 Gy to organs at risk (OARs) were calculated and compared. The lifetimemore » risk for secondary cancers was estimated according to the National Cancer Registry Programme Report 116. VMAT delivered the lowest maximum dose to the esophagus (4.03 Gy), bone (8.11 Gy), heart (2.11 Gy), spinal cord (6.45 Gy), and whole lung (5.66 Gy) as compared with other techniques (IMRT and 3DCRT). The volumes of OAR (esophagus) receiving more than 4 Gy were 0% for VMAT, 27.06% for IMRT, and up to 32.35% for 3DCRT. The estimated risk for secondary cancer in the respective OAR is considerably lower in VMAT compared with other techniques. The results of maximum doses and volumes of OARs suggest that the risk of secondary cancer induction for the spine in VMAT is lower than IMRT and 3DCRT, whereas VMAT has the best target coverage compared with the other techniques.« less

  3. SU-E-T-503: Intensity Modulated Proton Therapy (IMPT) Versus Intensity Modulated X-Ray Therapy (IMRT) for Patient with Hepatocellular Carcinoma: A Dosimetric Comparison

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Singh, H; Zhao, L; Prabhu, K

    2015-06-15

    Purpose This study compares the dosimetric parameters in treatment of unresectable hepatocellular carcinoma between intensity modulated proton therapy (IMPT) and intensity modulated x-ray radiation therapy (IMRT). Methods and Materials: We studied four patients treated at our institution. All patients were simulated supine with 4D-CT using a GE light speed simulator with a maximum slice thickness of 3mm. The average CT and an internal target volume to account for respiration motion were used for planning. Both IMRT and IMPT plans were created using Elekta’s CMSXiO treatment planning system (TPS). The prescription dose was 58.05 CGE in 15 fractions. The IMRT plansmore » had five beams with combination of co-planar and non-co-planar. The IMPT plans had 2 to 3 beams. Dose comparison was performed based on the averaged results of the four patients. Results The mean dose and V95% to PTV were 58.24CGE, 98.57% for IMPT, versus 57.34CGE and 96.68% for IMRT, respectively. The V10, V20, V30 and mean dose of the normal liver for IMPT were 23.10%, 18.61%, 13.75% and 9.78 CGE; and 47.19%, 37.55%, 22.73% and 17.12CGE for IMRT. The spinal cord didn’t receive any dose in IMPT technique, but received a maximum of 18.77CGE for IMRT. The IMPT gave lower maximum dose to the stomach as compared to IMRT (19.26 vs 26.35CGE). V14 for left and right kidney was 0% and 2.32% for IMPT and 3.89% and 29.54% for IMRT. The mean dose, V35, V40 and V45 for small bowl were similar in both techniques, 0.74CGE, 6.27cc, 4.85cc and 3.53 cc for IMPT, 3.47CGE, 9.73cc, 7.61cc 5.35cc for IMRT. Conclusion Based on this study, IMPT plans gave less dose to the critical structures such as normal liver, kidney, stomach and spinal cord as compared to IMRT plans, potentially leading to less toxicity and providing better quality of life for patients.« less

  4. Surface buildup dose dependence on photon field delivery technique for IMRT

    PubMed Central

    Yokoyama, Shigeru; Roberson, Peter L.; Litzenberg, Dale W.; Moran, Jean M.; Fraass, Benedick A.

    2004-01-01

    The more complex delivery techniques required for implementation of intensity‐modulated radiotherapy (IMRT) based on inverse planning optimization have changed the relationship between dose at depth and dose at buildup regions near the surface. Surface buildup dose is dependent on electron contamination primarily from the unblocked view of the flattening filter and secondarily from air and collimation systems. To evaluate the impact of beam segmentation on buildup dose, measurements were performed with 10×10 cm2 fields, which were delivered with 3 static 3.5×10 cm2 or 3×10 cm2 strips, 5 static 2×10 cm2 strips, 10 static 1×10 cm2 strips, and 1.1×10 cm2 dynamic delivery, compared with a 10×10 cm2 open field. Measurements were performed in water and Solid Water using parallel plate chambers, a stereotactic diode, and thermoluminescent dosimeters (TLDs) for a 6 MV X‐ray beam. Depth doses at 2 mm depth (relative to dose at 10 cm depth) were lower by 6%, 7%, 11%, and 10% for the above field delivery techniques, respectively, compared to the open field. These differences are most influenced by differences in multileaf collimator (MLC) transmission contributing to the useful beam. An example IMRT field was also studied to assess variations due to delivery technique (static vs. dynamic) and intensity level. Buildup dose is weakly dependent on the multileaf delivery technique for efficient IMRT fields. PACS numbers: 87.53.‐j, 87.53.Dq PMID:15738914

  5. Dosimetric evaluation of integrated IMRT treatment of the chest wall and supraclavicular region for breast cancer after modified radical mastectomy

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Yang, Bo; Wei, Xian-ding; Zhao, Yu-tian

    2014-07-01

    To investigate the dosimetric characteristics of irradiation of the chest wall and supraclavicular region as an integrated volume with intensity-modulated radiation therapy (IMRT) after modified radical mastectomy. This study included 246 patients who received modified radical mastectomy. The patients were scanned with computed tomography, and the chest wall (with or without the internal mammary lymph nodes) and supraclavicular region were delineated. For 143 patients, the chest wall and supraclavicular region were combined as an integrated planning volume and treated with IMRT. For 103 patients, conventional treatments were employed with 2 tangential fields for the chest wall, abutting a mixed fieldmore » of 6-MV x-rays (16 Gy) and 9-MeV electrons (34 Gy) for the upper supraclavicular region. The common prescription dose was 50 Gy/25 Fx/5 W to 90% of the target volume. The dosimetric characteristics of the chest wall, the supraclavicular region, and normal organs were compared. For the chest wall target, compared with conventional treatments, the integrated IMRT plans lowered the maximum dose, increased the minimum dose, and resulted in better conformity and uniformity of the target volume. There was an increase in minimum, average, and 95% prescription dose for the integrated IMRT plans in the supraclavicular region, and conformity and uniformity were improved. The V{sub 30} of the ipsilateral lung and V{sub 10}, V{sub 30}, and mean dose of the heart on the integrated IMRT plans were lower than those of the conventional plans. The V{sub 5} and V{sub 10} of the ipsilateral lung and V{sub 5} of the heart were higher on the integrated IMRT plans (p < 0.05) than on conventional plans. Without an increase in the radiation dose to organs at risk, the integrated IMRT treatment plans improved the dose distribution of the supraclavicular region and showed better dose conformity and uniformity of the integrated target volume of the chest wall and supraclavicular region.« less

  6. Analysis of the sources of uncertainty for EDR2 film‐based IMRT quality assurance

    PubMed Central

    Shi, Chengyu; Papanikolaou, Nikos; Yan, Yulong; Weng, Xuejun; Jiang, gyu

    2006-01-01

    In our institution, patient‐specific quality assurance (QA) for intensity‐modulated radiation therapy (IMRT) is usually performed by measuring the dose to a point using an ion chamber and by measuring the dose to a plane using film. In order to perform absolute dose comparison measurements using film, an accurate calibration curve should be used. In this paper, we investigate the film response curve uncertainty factors, including film batch differences, film processor temperature effect, film digitization, and treatment unit. In addition, we reviewed 50 patient‐specific IMRT QA procedures performed in our institution in order to quantify the sources of error in film‐based dosimetry. Our study showed that the EDR2 film dosimetry can be done with less than 3% uncertainty. The EDR2 film response was not affected by the choice of treatment unit provided the nominal energy was the same. This investigation of the different sources of uncertainties in the film calibration procedure can provide a better understanding of the film‐based dosimetry and can improve quality control for IMRT QA. PACS numbers: 87.86.Cd, 87.53.Xd, 87.57.Nk PMID:17533329

  7. Automated generation of IMRT treatment plans for prostate cancer patients with metal hip prostheses: Comparison of different planning strategies

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Voet, Peter W. J.; Dirkx, Maarten L. P.; Breedveld, Sebastiaan

    2013-07-15

    Purpose: To compare IMRT planning strategies for prostate cancer patients with metal hip prostheses.Methods: All plans were generated fully automatically (i.e., no human trial-and-error interactions) using iCycle, the authors' in-house developed algorithm for multicriterial selection of beam angles and optimization of fluence profiles, allowing objective comparison of planning strategies. For 18 prostate cancer patients (eight with bilateral hip prostheses, ten with a right-sided unilateral prosthesis), two planning strategies were evaluated: (i) full exclusion of beams containing beamlets that would deliver dose to the target after passing a prosthesis (IMRT{sub remove}) and (ii) exclusion of those beamlets only (IMRT{sub cut}). Plansmore » with optimized coplanar and noncoplanar beam arrangements were generated. Differences in PTV coverage and sparing of organs at risk (OARs) were quantified. The impact of beam number on plan quality was evaluated.Results: Especially for patients with bilateral hip prostheses, IMRT{sub cut} significantly improved rectum and bladder sparing compared to IMRT{sub remove}. For 9-beam coplanar plans, rectum V{sub 60Gy} reduced by 17.5%{+-} 15.0% (maximum 37.4%, p= 0.036) and rectum D{sub mean} by 9.4%{+-} 7.8% (maximum 19.8%, p= 0.036). Further improvements in OAR sparing were achievable by using noncoplanar beam setups, reducing rectum V{sub 60Gy} by another 4.6%{+-} 4.9% (p= 0.012) for noncoplanar 9-beam IMRT{sub cut} plans. Large reductions in rectum dose delivery were also observed when increasing the number of beam directions in the plans. For bilateral implants, the rectum V{sub 60Gy} was 37.3%{+-} 12.1% for coplanar 7-beam plans and reduced on average by 13.5% (maximum 30.1%, p= 0.012) for 15 directions.Conclusions: iCycle was able to automatically generate high quality plans for prostate cancer patients with prostheses. Excluding only beamlets that passed through the prostheses (IMRT{sub cut} strategy) significantly improved

  8. SU-E-T-478: Sliding Window Multi-Criteria IMRT Optimization

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Craft, D; Papp, D; Unkelbach, J

    2014-06-01

    Purpose: To demonstrate a method for what-you-see-is-what-you-get multi-criteria Pareto surface navigation for step and shoot IMRT treatment planning. Methods: We show mathematically how multiple sliding window treatment plans can be averaged to yield a single plan whose dose distribution is the dosimetric average of the averaged plans. This is incorporated into the Pareto surface navigation based approach to treatment planning in such a way that as the user navigates the surface, the plans he/she is viewing are ready to be delivered (i.e. there is no extra ‘segment the plans’ step that often leads to unacceptable plan degradation in step andmore » shoot Pareto surface navigation). We also describe how the technique can be applied to VMAT. Briefly, sliding window VMAT plans are created such that MLC leaves paint out fluence maps every 15 degrees or so. These fluence map leaf trajectories are averaged in the same way the static beam IMRT ones are. Results: We show mathematically that fluence maps are exactly averaged using our leaf sweep averaging algorithm. Leaf transmission and output factor corrections effects, which are ignored in this work, can lead to small errors in terms of the dose distributions not being exactly averaged even though the fluence maps are. However, our demonstrations show that the dose distributions are almost exactly averaged as well. We demonstrate the technique both for IMRT and VMAT. Conclusions: By turning to sliding window delivery, we show that the problem of losing plan fidelity during the conversion of an idealized fluence map plan into a deliverable plan is remedied. This will allow for multicriteria optimization that avoids the pitfall that the planning has to be redone after the conversion into MLC segments due to plan quality decline. David Craft partially funded by RaySearch Laboratories.« less

  9. Dosimetric comparison between Volumetric Modulated Arc Therapy (VMAT) vs Intensity Modulated Radiation Therapy (IMRT) for radiotherapy of mid esophageal carcinoma.

    PubMed

    Kataria, Tejinder; Govardhan, H B; Gupta, Deepak; Mohanraj, U; Bisht, Shyam Singh; Sambasivaselli, R; Goyal, S; Abhishek, A; Srivatsava, A; Pushpan, L; Kumar, V; Vikraman, S

    2014-01-01

    Dosimetric comparison of VMAT with IMRT in middle third esophageal cancer for planning target volume (PTV) and organs at risk (OAR). Ten patients in various stages from I‒III were inducted in the neo-adjuvant chemoradiation protocol for this study. The prescribed dose was 4500 cGy in 25 fractions. Both VMAT and IMRT plan were generated in all cases and Dose Volume Histogram (DVH) comparative analysis was performed for PTV and OAR. Paired t-test was used for statistical analysis. The PTV Dmean and D95 in IMRT and VMAT plan were 4566.6±50.6 cGy vs 4462.8±81.8 cGy (P=0.1) and 4379.8±50.6 cGy Vs 4424.3±109.8 cGy (P=0.1), respectively. The CI and HI for PTV in IMRT vs VMAT plans were 0.96±0.02 vs 0.97±0.01 (P=0.4) and 10.58±3.07 vs 9.45±2.42 (P=0.2), respectively. Lung doses for VMAT vs IMRT were 4.19 vs 2.59% (P=0.03) for V35-7.63 vs 4.76% (P=0.01) for V30-13.6 vs 9.98% (P=0.01) for V25-24.77 vs 18.57% (P=0.04) for V20-46.5 vs 34.73% (P=0.002) for V15. The Mean Lung Dose (MLD) was reduced by VMAT technique compared to IMRT; 1524.6±308.37 cGy and 1353±186.32 cGy (P=0.012). There was no change in Dmax to spinal cord in both the techniques. There was a dose reduction by VMAT compared to IMRT to the heart but it was statistically insignificant; V35-6.75% vs 5.55% (P=0.223); V30-12.3% vs 10.91% (P=0.352); V25-21.81% vs 20.16% (P=0.459); V20-38.11% vs 32.88% (P=0.070); V15-61.05% vs 54.2% (P=0.10). VMAT can be a better option in treating mid esophageal carcinoma as compared to IMRT. The VMAT plans resulted in equivalent or superior dose distribution with a reduction in the dose to lung and heart.

  10. SU-E-T-233: Cyberknife Versus Linac IMRT for Dose Comparision in Hypofractionated Hemi Larynx Irradiation of Early Stage True Vocal Cord Cancer: A Dosimetric Study

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ding, C; Lee, P; Jiang, S

    2015-06-15

    Purpose: To compare dosimetric data of patients treated for early-stage larynx cancer on Cyberknife and Linac IMRT. Methods: Nine patients were treated with Cyberknife to a dose of 45 Gy in 10 fractions of the involved hemilarynx. The prescription dose provided at least 95% of PTV coverage. After Cyberknife treatment, the CT images and contours were sent to Pinnacle treatment planning system for IMRT planning on a regular SBRT linac with same dose prescription and constrains. Dose to target and normal tissue, including the arytenoids, cord, carotid arteries, thyroid, and skin, were analyzed using dose volume histograms. Results: For Cyberknifemore » plan, the conformity indices are within 1.11–1.33. The average dose to the contralateral arytenoids for Cyberknife plans was 28.9±6.5Gy), which is lower than the same mean dose for IMRT plans (34.0±5.2 Gy). The average maximum dose to the ipsilateral and contralateral carotid artery were 20.6 ±9.1 Gy and 10.2±6.0 Gy respectively for Cybeknife comparing with 22.1±8.0 Gy and 12.0±5.1 Gy for IMRT. The mean dose to the thyroid was 3.6±2.2 Gy for Cyberknife and 3.4±2.4 Gy for IMRT. As shown in DVH, the Cyberknife can deliver less dose to the normal tissue which is close to target area comparing with IMRT Plans. However, IMRT plan’s can give more sparing for the critical organs which is far away from the target area. Conclusion: We have compared the dosimetric parameters of Cyberknife and linac IMRT plans for patients with early-stage larynx cancer. Both Cyberknife and IMRT plans can achieve conformal dose distribution to the target area. Cyberknife was able to reduce normal tissue dose in high doses region while IMRT plans can reduce the dose of the normal tissue at the low dose region. These dosimetric parameters can be used to guide future prospective protocols using SBRT for larynx cancer.« less

  11. Patient-specific IMRT verification using independent fluence-based dose calculation software: experimental benchmarking and initial clinical experience.

    PubMed

    Georg, Dietmar; Stock, Markus; Kroupa, Bernhard; Olofsson, Jörgen; Nyholm, Tufve; Ahnesjö, Anders; Karlsson, Mikael

    2007-08-21

    Experimental methods are commonly used for patient-specific intensity-modulated radiotherapy (IMRT) verification. The purpose of this study was to investigate the accuracy and performance of independent dose calculation software (denoted as 'MUV' (monitor unit verification)) for patient-specific quality assurance (QA). 52 patients receiving step-and-shoot IMRT were considered. IMRT plans were recalculated by the treatment planning systems (TPS) in a dedicated QA phantom, in which an experimental 1D and 2D verification (0.3 cm(3) ionization chamber; films) was performed. Additionally, an independent dose calculation was performed. The fluence-based algorithm of MUV accounts for collimator transmission, rounded leaf ends, tongue-and-groove effect, backscatter to the monitor chamber and scatter from the flattening filter. The dose calculation utilizes a pencil beam model based on a beam quality index. DICOM RT files from patient plans, exported from the TPS, were directly used as patient-specific input data in MUV. For composite IMRT plans, average deviations in the high dose region between ionization chamber measurements and point dose calculations performed with the TPS and MUV were 1.6 +/- 1.2% and 0.5 +/- 1.1% (1 S.D.). The dose deviations between MUV and TPS slightly depended on the distance from the isocentre position. For individual intensity-modulated beams (total 367), an average deviation of 1.1 +/- 2.9% was determined between calculations performed with the TPS and with MUV, with maximum deviations up to 14%. However, absolute dose deviations were mostly less than 3 cGy. Based on the current results, we aim to apply a confidence limit of 3% (with respect to the prescribed dose) or 6 cGy for routine IMRT verification. For off-axis points at distances larger than 5 cm and for low dose regions, we consider 5% dose deviation or 10 cGy acceptable. The time needed for an independent calculation compares very favourably with the net time for an experimental

  12. A dosimetric analysis of intensity-modulated radiation therapy (IMRT) as an alternative to adjuvant high-dose-rate (HDR) brachytherapy in early endometrial cancer patients

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Aydogan, Bulent; Mundt, Arno J.; Department of Radiation Oncology, University of Illinois at Chicago, Chicago, IL

    2006-05-01

    Purpose: To evaluate the role of intensity-modulated radiation treatment (IMRT) as an alternative to high-dose-rate (HDR) brachytherapy in the treatment of the vagina in postoperative early endometrial cancer patients after surgery. Methods and Materials: Planning computed tomography (CT) scans of 10 patients previously treated with HDR were used in this study. In all cases, a dose of 700 cGy/fraction was prescribed at a distance of 0.5 cm from the cylinder surface. The same CT scans were then used in IMRT planning. In this paradigm, the vaginal cylinder represents a component of a hypothetical immobilization system that would be indexed tomore » the linac treatment table. Results: Our study showed that IMRT provided relatively lower rectal doses than HDR when treatment was prescribed at a distance of 0.5 cm away from the cylinder surface. Maximum rectal doses were lower with IMRT compared with HDR (average: 89.0% vs. 142.6%, respectively, p < 0.05). Moreover, the mean rectal dose was lower in IMRT plans compared with HDR plans with treatment prescribed either to the surface (average: 14.8% vs. 21.4%, respectively, p < 0.05) or to 0.5 cm (average: 19.6% vs. 33.5%, respectively, p < 0.05). IMRT plans had planning target volume (PTV) coverage comparable with HDR (average PTV minimum for treatment prescribed to 0.5 cm: 93.9% vs. 92.1%, p = 0.71, respectively) with less inhomogeneity (average PTV maximum: 110.8% vs. 381.6%, p < 0.05). Conclusion: Our dosimetric analysis suggests that when used in conjunction with a suitable immobilization system, IMRT may provide an alternative to HDR brachytherapy in women with early endometrial cancer after hysterectomy. However, more studies are needed to evaluate the clinical merit of the IMRT in these patients.« less

  13. A GPU-accelerated Monte Carlo dose calculation platform and its application toward validating an MRI-guided radiation therapy beam model

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wang, Yuhe; Mazur, Thomas R.; Green, Olga

    Purpose: The clinical commissioning of IMRT subject to a magnetic field is challenging. The purpose of this work is to develop a GPU-accelerated Monte Carlo dose calculation platform based on PENELOPE and then use the platform to validate a vendor-provided MRIdian head model toward quality assurance of clinical IMRT treatment plans subject to a 0.35 T magnetic field. Methods: PENELOPE was first translated from FORTRAN to C++ and the result was confirmed to produce equivalent results to the original code. The C++ code was then adapted to CUDA in a workflow optimized for GPU architecture. The original code was expandedmore » to include voxelized transport with Woodcock tracking, faster electron/positron propagation in a magnetic field, and several features that make gPENELOPE highly user-friendly. Moreover, the vendor-provided MRIdian head model was incorporated into the code in an effort to apply gPENELOPE as both an accurate and rapid dose validation system. A set of experimental measurements were performed on the MRIdian system to examine the accuracy of both the head model and gPENELOPE. Ultimately, gPENELOPE was applied toward independent validation of patient doses calculated by MRIdian’s KMC. Results: An acceleration factor of 152 was achieved in comparison to the original single-thread FORTRAN implementation with the original accuracy being preserved. For 16 treatment plans including stomach (4), lung (2), liver (3), adrenal gland (2), pancreas (2), spleen(1), mediastinum (1), and breast (1), the MRIdian dose calculation engine agrees with gPENELOPE with a mean gamma passing rate of 99.1% ± 0.6% (2%/2 mm). Conclusions: A Monte Carlo simulation platform was developed based on a GPU- accelerated version of PENELOPE. This platform was used to validate that both the vendor-provided head model and fast Monte Carlo engine used by the MRIdian system are accurate in modeling radiation transport in a patient using 2%/2 mm gamma criteria. Future applications of

  14. NTCP modeling analysis of acute hematologic toxicity in whole pelvic radiation therapy for gynecologic malignancies - A dosimetric comparison of IMRT and spot-scanning proton therapy (SSPT).

    PubMed

    Yoshimura, Takaaki; Kinoshita, Rumiko; Onodera, Shunsuke; Toramatsu, Chie; Suzuki, Ryusuke; Ito, Yoichi M; Takao, Seishin; Matsuura, Taeko; Matsuzaki, Yuka; Umegaki, Kikuo; Shirato, Hiroki; Shimizu, Shinichi

    2016-09-01

    This treatment planning study was conducted to determine whether spot scanning proton beam therapy (SSPT) reduces the risk of grade ⩾3 hematologic toxicity (HT3+) compared with intensity modulated radiation therapy (IMRT) for postoperative whole pelvic radiation therapy (WPRT). The normal tissue complication probability (NTCP) of the risk of HT3+ was used as an in silico surrogate marker in this analysis. IMRT and SSPT plans were created for 13 gynecologic malignancy patients who had received hysterectomies. The IMRT plans were generated using the 7-fields step and shoot technique. The SSPT plans were generated using anterior-posterior field with single field optimization. Using the relative biological effectives (RBE) value of 1.0 for IMRT and 1.1 for SSPT, the prescribed dose was 45Gy(RBE) in 1.8Gy(RBE) per fractions for 95% of the planning target volume (PTV). The homogeneity index (HI) and the conformity index (CI) of the PTV were also compared. The bone marrow (BM) and femoral head doses using SSPT were significantly lower than with IMRT. The NTCP modeling analysis showed that the risk of HT3+ using SSPT was significantly lower than with IMRT (NTCP=0.04±0.01 and 0.19±0.03, p=0.0002, respectively). There were no significant differences in the CI and HI of the PTV between IMRT and SSPT (CI=0.97±0.01 and 0.96±0.02, p=0.3177, and HI=1.24±0.11 and 1.27±0.05, p=0.8473, respectively). The SSPT achieves significant reductions in the dose to BM without compromising target coverage, compared with IMRT. The NTCP value for HT3+ in SSPT was significantly lower than in IMRT. Copyright © 2016 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  15. A versatile program for the calculation of linear accelerator room shielding.

    PubMed

    Hassan, Zeinab El-Taher; Farag, Nehad M; Elshemey, Wael M

    2018-03-22

    This work aims at designing a computer program to calculate the necessary amount of shielding for a given or proposed linear accelerator room design in radiotherapy. The program (Shield Calculation in Radiotherapy, SCR) has been developed using Microsoft Visual Basic. It applies the treatment room shielding calculations of NCRP report no. 151 to calculate proper shielding thicknesses for a given linear accelerator treatment room design. The program is composed of six main user-friendly interfaces. The first enables the user to upload their choice of treatment room design and to measure the distances required for shielding calculations. The second interface enables the user to calculate the primary barrier thickness in case of three-dimensional conventional radiotherapy (3D-CRT), intensity modulated radiotherapy (IMRT) and total body irradiation (TBI). The third interface calculates the required secondary barrier thickness due to both scattered and leakage radiation. The fourth and fifth interfaces provide a means to calculate the photon dose equivalent for low and high energy radiation, respectively, in door and maze areas. The sixth interface enables the user to calculate the skyshine radiation for photons and neutrons. The SCR program has been successfully validated, precisely reproducing all of the calculated examples presented in NCRP report no. 151 in a simple and fast manner. Moreover, it easily performed the same calculations for a test design that was also calculated manually, and produced the same results. The program includes a new and important feature that is the ability to calculate required treatment room thickness in case of IMRT and TBI. It is characterised by simplicity, precision, data saving, printing and retrieval, in addition to providing a means for uploading and testing any proposed treatment room shielding design. The SCR program provides comprehensive, simple, fast and accurate room shielding calculations in radiotherapy.

  16. SU-F-T-266: Dynalogs Based Evaluation of Different Dose Rate IMRT Using DVH and Gamma Index

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ahmed, S; Ahmed, S; Ahmed, F

    2016-06-15

    Purpose: This work investigates the impact of low and high dose rate on IMRT through Dynalogs by evaluating Gamma Index and Dose Volume Histogram. Methods: The Eclipse™ treatment planning software was used to generate plans on prostate and head and neck sites. A range of dose rates 300 MU/min and 600 MU/min were applied to each plan in order to investigate their effect on the beam ON time, efficiency and accuracy. Each plan had distinct monitor units per fraction, delivery time, mean dose rate and leaf speed. The DVH data was used in the assessment of the conformity and planmore » quality.The treatments were delivered on Varian™ Clinac 2100C accelerator equipped with 120 leaf millennium MLC. Dynalogs of each plan were analyzed by MATLAB™ program. Fluence measurements were performed using the Sun Nuclear™ 2D diode array and results were assessed, based on Gamma analysis of dose fluence maps, beam delivery statistics and Dynalogs data. Results: Minor differences found by adjusted R-squared analysis of DVH’s for all the plans with different dose rates. It has been also found that more and larger fields have greater time reduction at high dose rate and there was a sharp decrease in number of control points observed in dynalog files by switching dose rate from 300 MU/min to 600 MU/min. Gamma Analysis of all plans passes the confidence limit of ≥95% with greater number of passing points in 300 MU/min dose rate plans. Conclusion: The dynalog files are compatible tool for software based IMRT QA. It can work perfectly parallel to measurement based QA setup and stand-by procedure for pre and post delivery of treatment plan.« less

  17. Investigating ion recombination effects in a liquid-filled ionization chamber array used for IMRT QA measurements

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Knill, Cory, E-mail: knillcor@gmail.com; Snyder, Michael; Rakowski, Joseph T.

    Purpose: PTW’s Octavius 1000 SRS array performs IMRT quality assurance (QA) measurements with liquid-filled ionization chambers (LICs) to allow closer detector spacing and higher resolution, compared to air-filled QA devices. However, reduced ion mobility in LICs relative to air leads to increased ion recombination effects and reduced collection efficiencies that are dependent on Linac pulse frequency and pulse dose. These pulse parameters are variable during an IMRT delivery, which affects QA results. In this study, (1) 1000 SRS collection efficiencies were measured as a function of pulse frequency and pulse dose, (2) two methods were developed to correct changes inmore » collection efficiencies during IMRT QA measurements, and the effects of these corrections on QA pass rates were compared. Methods: To obtain collection efficiencies, the OCTAVIUS 1000 SRS was used to measure open fields of varying pulse frequency, pulse dose, and beam energy with results normalized to air-filled chamber measurements. Changes in ratios of 1000 SRS to chamber measured dose were attributed to changing collection efficiencies, which were then correlated to pulse parameters using regression analysis. The usefulness of the derived corrections was then evaluated using 6 MV and 10FFF SBRT RapidArc plans delivered to the OCTAVIUS 4D system using a TrueBeam (Varian Medical Systems) linear accelerator equipped with a high definition multileaf collimator. For the first correction, MATLAB software was developed that calculates pulse frequency and pulse dose for each detector, using measurement and DICOM RT Plan files. Pulse information is converted to collection efficiency, and measurements are corrected by multiplying detector dose by ratios of calibration to measured collection efficiencies. For the second correction the MU/min in the daily 1000 SRS calibration was chosen to match the average MU/min of the volumetric modulated arc therapy plan. Effects of the two corrections on QA

  18. SU-E-T-49: A Multi-Institutional Study of Independent Dose Verification for IMRT

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Baba, H; Tachibana, H; Kamima, T

    2015-06-15

    Purpose: AAPM TG114 does not cover the independent verification for IMRT. We conducted a study of independent dose verification for IMRT in seven institutes to show the feasibility. Methods: 384 IMRT plans in the sites of prostate and head and neck (HN) were collected from the institutes, where the planning was performed using Eclipse and Pinnacle3 with the two techniques of step and shoot (S&S) and sliding window (SW). All of the institutes used a same independent dose verification software program (Simple MU Analysis: SMU, Triangle Product, Ishikawa, JP), which is Clarkson-based and CT images were used to compute radiologicalmore » path length. An ion-chamber measurement in a water-equivalent slab phantom was performed to compare the doses computed using the TPS and an independent dose verification program. Additionally, the agreement in dose computed in patient CT images between using the TPS and using the SMU was assessed. The dose of the composite beams in the plan was evaluated. Results: The agreement between the measurement and the SMU were −2.3±1.9 % and −5.6±3.6 % for prostate and HN sites, respectively. The agreement between the TPSs and the SMU were −2.1±1.9 % and −3.0±3.7 for prostate and HN sites, respectively. There was a negative systematic difference with similar standard deviation and the difference was larger in the HN site. The S&S technique showed a statistically significant difference between the SW. Because the Clarkson-based method in the independent program underestimated (cannot consider) the dose under the MLC. Conclusion: The accuracy would be improved when the Clarkson-based algorithm should be modified for IMRT and the tolerance level would be within 5%.« less

  19. Knowledge-based IMRT planning for individual liver cancer patients using a novel specific model.

    PubMed

    Yu, Gang; Li, Yang; Feng, Ziwei; Tao, Cheng; Yu, Zuyi; Li, Baosheng; Li, Dengwang

    2018-03-27

    The purpose of this work is to benchmark RapidPlan against clinical plans for liver Intensity-modulated radiotherapy (IMRT) treatment of patients with special anatomical characteristics, and to investigate the prediction capability of the general model (Model-G) versus our specific model (Model-S). A library consisting of 60 liver cancer patients with IMRT planning was used to set up two models (Model-S, Model-G), using the RapidPlan knowledge-based planning system. Model-S consisted of 30 patients with special anatomical characteristics where the distance from planning target volume (PTV) to the right kidney was less than three centimeters and Model-G was configurated using all 60 patients in this library. Knowledge-based IMRT plans were created for the evaluation group formed of 13 patients similar to those included in Model-S by Model-G, Model-S and manually (M), named RPG-plans, RPS-plans and M-plans, respectively. The differences in the dose-volume histograms (DVHs) were compared, not only between RP-plans and their respective M-plans, but also between RPG-plans and RPS-plans. For all 13 patients, RapidPlan could automatically produce clinically acceptable plans. Comparing RP-plans to M-plans, RP-plans improved V 95% of PTV and had greater dose sparing in the right kidney. For the normal liver, RPG-plans delivered similar doses, while RPS-plans delivered a higher dose than M-plans. With respect to RapidPlan models, RPS-plans had better conformity index (CI) values and delivered lower doses to the right kidney V 20Gy and maximizing point doses to spinal cord, while delivering higher doses to the normal liver. The study shows that RapidPlan can create high-quality plans, and our specific model can improve the CI of PTV, resulting in more sparing of OAR in IMRT for individual liver cancer patients.

  20. Deep nets vs expert designed features in medical physics: An IMRT QA case study.

    PubMed

    Interian, Yannet; Rideout, Vincent; Kearney, Vasant P; Gennatas, Efstathios; Morin, Olivier; Cheung, Joey; Solberg, Timothy; Valdes, Gilmer

    2018-03-30

    The purpose of this study was to compare the performance of Deep Neural Networks against a technique designed by domain experts in the prediction of gamma passing rates for Intensity Modulated Radiation Therapy Quality Assurance (IMRT QA). A total of 498 IMRT plans across all treatment sites were planned in Eclipse version 11 and delivered using a dynamic sliding window technique on Clinac iX or TrueBeam Linacs. Measurements were performed using a commercial 2D diode array, and passing rates for 3%/3 mm local dose/distance-to-agreement (DTA) were recorded. Separately, fluence maps calculated for each plan were used as inputs to a convolution neural network (CNN). The CNNs were trained to predict IMRT QA gamma passing rates using TensorFlow and Keras. A set of model architectures, inspired by the convolutional blocks of the VGG-16 ImageNet model, were constructed and implemented. Synthetic data, created by rotating and translating the fluence maps during training, was created to boost the performance of the CNNs. Dropout, batch normalization, and data augmentation were utilized to help train the model. The performance of the CNNs was compared to a generalized Poisson regression model, previously developed for this application, which used 78 expert designed features. Deep Neural Networks without domain knowledge achieved comparable performance to a baseline system designed by domain experts in the prediction of 3%/3 mm Local gamma passing rates. An ensemble of neural nets resulted in a mean absolute error (MAE) of 0.70 ± 0.05 and the domain expert model resulted in a 0.74 ± 0.06. Convolutional neural networks (CNNs) with transfer learning can predict IMRT QA passing rates by automatically designing features from the fluence maps without human expert supervision. Predictions from CNNs are comparable to a system carefully designed by physicist experts. © 2018 American Association of Physicists in Medicine.

  1. SU-F-BRD-02: Application of ARCHERRT-- A GPU-Based Monte Carlo Dose Engine for Radiation Therapy -- to Tomotherapy and Patient-Independent IMRT

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Su, L; Du, X; Liu, T

    Purpose: As a module of ARCHER -- Accelerated Radiation-transport Computations in Heterogeneous EnviRonments, ARCHER{sub RT} is designed for RadioTherapy (RT) dose calculation. This paper describes the application of ARCHERRT on patient-dependent TomoTherapy and patient-independent IMRT. It also conducts a 'fair' comparison of different GPUs and multicore CPU. Methods: The source input used for patient-dependent TomoTherapy is phase space file (PSF) generated from optimized plan. For patient-independent IMRT, the open filed PSF is used for different cases. The intensity modulation is simulated by fluence map. The GEANT4 code is used as benchmark. DVH and gamma index test are employed to evaluatemore » the accuracy of ARCHER{sub RT} code. Some previous studies reported misleading speedups by comparing GPU code with serial CPU code. To perform a fairer comparison, we write multi-thread code with OpenMP to fully exploit computing potential of CPU. The hardware involved in this study are a 6-core Intel E5-2620 CPU and 6 NVIDIA M2090 GPUs, a K20 GPU and a K40 GPU. Results: Dosimetric results from ARCHER{sub RT} and GEANT4 show good agreement. The 2%/2mm gamma test pass rates for different clinical cases are 97.2% to 99.7%. A single M2090 GPU needs 50~79 seconds for the simulation to achieve a statistical error of 1% in the PTV. The K40 card is about 1.7∼1.8 times faster than M2090 card. Using 6 M2090 card, the simulation can be finished in about 10 seconds. For comparison, Intel E5-2620 needs 507∼879 seconds for the same simulation. Conclusion: We successfully applied ARCHER{sub RT} to Tomotherapy and patient-independent IMRT, and conducted a fair comparison between GPU and CPU performance. The ARCHER{sub RT} code is both accurate and efficient and may be used towards clinical applications.« less

  2. SU-F-BRD-05: Dosimetric Comparison of Protocol-Based SBRT Lung Treatment Modalities: Statistically Significant VMAT Advantages Over Fixed- Beam IMRT

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Best, R; Harrell, A; Geesey, C

    2014-06-15

    Purpose: The purpose of this study is to inter-compare and find statistically significant differences between flattened field fixed-beam (FB) IMRT with flattening-filter free (FFF) volumetric modulated arc therapy (VMAT) for stereotactic body radiation therapy SBRT. Methods: SBRT plans using FB IMRT and FFF VMAT were generated for fifteen SBRT lung patients using 6 MV beams. For each patient, both IMRT and VMAT plans were created for comparison. Plans were generated utilizing RTOG 0915 (peripheral, 10 patients) and RTOG 0813 (medial, 5 patients) lung protocols. Target dose, critical structure dose, and treatment time were compared and tested for statistical significance. Parametersmore » of interest included prescription isodose surface coverage, target dose heterogeneity, high dose spillage (location and volume), low dose spillage (location and volume), lung dose spillage, and critical structure maximum- and volumetric-dose limits. Results: For all criteria, we found equivalent or higher conformality with VMAT plans as well as reduced critical structure doses. Several differences passed a Student's t-test of significance: VMAT reduced the high dose spillage, evaluated with conformality index (CI), by an average of 9.4%±15.1% (p=0.030) compared to IMRT. VMAT plans reduced the lung volume receiving 20 Gy by 16.2%±15.0% (p=0.016) compared with IMRT. For the RTOG 0915 peripheral lesions, the volumes of lung receiving 12.4 Gy and 11.6 Gy were reduced by 27.0%±13.8% and 27.5%±12.6% (for both, p<0.001) in VMAT plans. Of the 26 protocol pass/fail criteria, VMAT plans were able to achieve an average of 0.2±0.7 (p=0.026) more constraints than the IMRT plans. Conclusions: FFF VMAT has dosimetric advantages over fixed beam IMRT for lung SBRT. Significant advantages included increased dose conformity, and reduced organs-at-risk doses. The overall improvements in terms of protocol pass/fail criteria were more modest and will require more patient data to establish

  3. Parotid gland shrinkage during IMRT predicts the time to Xerostomia resolution.

    PubMed

    Sanguineti, Giuseppe; Ricchetti, Francesco; Wu, Binbin; McNutt, Todd; Fiorino, Claudio

    2015-01-17

    To assess the impact of mid-treatment parotid gland shrinkage on long term xerostomia during IMRT for oropharyngeal SCC. All patients treated with IMRT at a single Institution from November 2007 to June 2010 and undergoing weekly CT scans were selected. Parotid glands were contoured retrospectively on the mid treatment CT scan. For each parotid gland, the percent change relative to the planning volume was calculated and combined as weighted average. Patients were considered to be xerostomic if developed GR2+ dry mouth according to CTCAE v3.0. Predictors of the time to xerostomia resolution or downgrade to 1 were investigated at both uni- and multivariate analysis. 85 patients were selected. With a median follow up of 35.8 months (range: 2.4-62.6 months), the actuarial rate of xerostomia is 26.2% (SD: 5.3%) and 15.9% (SD: 5.3%) at 2 and 3 yrs, respectively. At multivariate analysis, mid-treatment shrink along with weighted average mean parotid dose at planning and body mass index are independent predictors of the time to xerostomia resolution. Patients were pooled in 4 groups based on median values of both mid-treatment shrink (cut-off: 19.6%) and mean WA parotid pl-D (cut-off: 35.7 Gy). Patients with a higher than median parotid dose at planning and who showed poor shrinkage at mid treatment are the ones with the outcome significantly worse (3-yr rate of xerostomia ≈ 50%) than the other three subgroups (3-yr rate of xerostomia ≈ 10%). For a given planned dose, patients whose parotids significantly shrink during IMRT are less likely to be long-term supplemental fluids dependent.

  4. SU-F-BRE-08: Feasibility of 3D Printed Patient Specific Phantoms for IMRT/IGRT QA

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ehler, E; Higgins, P; Dusenbery, K

    Purpose: Test the feasibility of 3D printed, per-patient phantoms for IMRT QA to analyze the treatment delivery quality within the patient geometry. Methods: Using the head and neck region of an anthropomorphic phantom as a substitute for an actual patient, a soft-tissue equivalent model was constructed with the use of a 3D printer. A nine-field IMRT plan was constructed and dose verification measurements were performed for the 3D printed phantom. During the delivery of the IMRT QA on to the 3D printed phantom, the same patient positioning indexing system was used on the phantom and image guidance (cone beam CT)more » was used to localize the phantom, serving as a test of the IGRT system as well. The 3D printed phantom was designed to accommodate four radiochromic film planes (two axial, one coronal and one sagittal) and an ionization chamber measurement. As a frame of comparison, the IMRT QA was also performed on traditional phantoms. Dosimetric tolerance levels such as 3mm / 3% Gamma Index as well as 3% and 5% dose difference were considered. All detector systems were calibrated against a NIST traceable ionization chamber. Results: Comparison of results 3D printed patient phantom with the standard IMRT QA systems showed similar passing rates for the 3D printed phantom and the standard phantoms. However, the locations of the failing regions did not necessarily correlate. The 3D printed phantom was localized within 1 mm and 1° using on-board cone beam CT. Conclusion: A custom phantom was created using a 3D printer. It was determined that the use of patient specific phantoms to perform dosimetric verification and estimate the dose in the patient is feasible. In addition, end-to-end testing on a per-patient basis was possible with the 3D printed phantom. Further refinement of the phantom construction process is needed for routine clinical use.« less

  5. SU-E-T-503: IMRT Optimization Using Monte Carlo Dose Engine: The Effect of Statistical Uncertainty.

    PubMed

    Tian, Z; Jia, X; Graves, Y; Uribe-Sanchez, A; Jiang, S

    2012-06-01

    With the development of ultra-fast GPU-based Monte Carlo (MC) dose engine, it becomes clinically realistic to compute the dose-deposition coefficients (DDC) for IMRT optimization using MC simulation. However, it is still time-consuming if we want to compute DDC with small statistical uncertainty. This work studies the effects of the statistical error in DDC matrix on IMRT optimization. The MC-computed DDC matrices are simulated here by adding statistical uncertainties at a desired level to the ones generated with a finite-size pencil beam algorithm. A statistical uncertainty model for MC dose calculation is employed. We adopt a penalty-based quadratic optimization model and gradient descent method to optimize fluence map and then recalculate the corresponding actual dose distribution using the noise-free DDC matrix. The impacts of DDC noise are assessed in terms of the deviation of the resulted dose distributions. We have also used a stochastic perturbation theory to theoretically estimate the statistical errors of dose distributions on a simplified optimization model. A head-and-neck case is used to investigate the perturbation to IMRT plan due to MC's statistical uncertainty. The relative errors of the final dose distributions of the optimized IMRT are found to be much smaller than those in the DDC matrix, which is consistent with our theoretical estimation. When history number is decreased from 108 to 106, the dose-volume-histograms are still very similar to the error-free DVHs while the error in DDC is about 3.8%. The results illustrate that the statistical errors in the DDC matrix have a relatively small effect on IMRT optimization in dose domain. This indicates we can use relatively small number of histories to obtain the DDC matrix with MC simulation within a reasonable amount of time, without considerably compromising the accuracy of the optimized treatment plan. This work is supported by Varian Medical Systems through a Master Research Agreement. © 2012

  6. On the performances of different IMRT treatment planning systems for selected paediatric cases

    PubMed Central

    Fogliata, Antonella; Nicolini, Giorgia; Alber, Markus; Åsell, Mats; Clivio, Alessandro; Dobler, Barbara; Larsson, Malin; Lohr, Frank; Lorenz, Friedlieb; Muzik, Jan; Polednik, Martin; Vanetti, Eugenio; Wolff, Dirk; Wyttenbach, Rolf; Cozzi, Luca

    2007-01-01

    Background To evaluate the performance of seven different TPS (Treatment Planning Systems: Corvus, Eclipse, Hyperion, KonRad, Oncentra Masterplan, Pinnacle and PrecisePLAN) when intensity modulated (IMRT) plans are designed for paediatric tumours. Methods Datasets (CT images and volumes of interest) of four patients were used to design IMRT plans. The tumour types were: one extraosseous, intrathoracic Ewing Sarcoma; one mediastinal Rhabdomyosarcoma; one metastatic Rhabdomyosarcoma of the anus; one Wilm's tumour of the left kidney with multiple liver metastases. Prescribed doses ranged from 18 to 54.4 Gy. To minimise variability, the same beam geometry and clinical goals were imposed on all systems for every patient. Results were analysed in terms of dose distributions and dose volume histograms. Results For all patients, IMRT plans lead to acceptable treatments in terms of conformal avoidance since most of the dose objectives for Organs At Risk (OARs) were met, and the Conformity Index (averaged over all TPS and patients) ranged from 1.14 to 1.58 on primary target volumes and from 1.07 to 1.37 on boost volumes. The healthy tissue involvement was measured in terms of several parameters, and the average mean dose ranged from 4.6 to 13.7 Gy. A global scoring method was developed to evaluate plans according to their degree of success in meeting dose objectives (lower scores are better than higher ones). For OARs the range of scores was between 0.75 ± 0.15 (Eclipse) to 0.92 ± 0.18 (Pinnacle3 with physical optimisation). For target volumes, the score ranged from 0.05 ± 0.05 (Pinnacle3 with physical optimisation) to 0.16 ± 0.07 (Corvus). Conclusion A set of complex paediatric cases presented a variety of individual treatment planning challenges. Despite the large spread of results, inverse planning systems offer promising results for IMRT delivery, hence widening the treatment strategies for this very sensitive class of patients. PMID:17302972

  7. Can IMRT or Brachytherapy Reduce Dysphagia Associated With Chemoradiotherapy of Head and Neck Cancer? The Michigan and Rotterdam Experiences

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Eisbruch, Avraham; Levendag, Peter C.; Feng, Felix Y.

    Purpose: Dysphagia is a major late complication of intensive chemoradiotherapy of head and neck cancer. The initial clinical results of intensity-modulated radiotherapy (IMRT), or brachytherapy, planned specifically to reduce dysphagia are presented. Patients and Methods: Previous research at Michigan University has suggested that the pharyngeal constrictors and glottic and supraglottic larynx are likely structures whose damage by chemo-RT causes dysphagia and aspiration. In a prospective Michigan trial, 36 patients with oropharyngeal (n = 31) or nasopharyngeal (n = 5) cancer underwent chemo-IMRT. IMRT cost functions included sparing noninvolved pharyngeal constrictors and the glottic and supraglottic larynx. After a review ofmore » published studies, the retropharyngeal nodes at risk were defined as the lateral, but not the medial, retropharyngeal nodes, which facilitated sparing of the swallowing structures. In Rotterdam, 77 patients with oropharyngeal cancer were treated with IMRT, three dimensional RT, or conventional RT; also one-half received brachytherapy. The dysphagia endpoints included videofluoroscopy and observer-assessed scores at Michigan and patient-reported quality-of-life instruments in both studies. Results: In both studies, the doses to the upper and middle constrictors correlated highly with the dysphagia endpoints. In addition, doses to the glottic and supraglottic larynx were significant in the Michigan series. In the Rotterdam series, brachytherapy (which reduced the doses to the swallowing structures) was the only significant factor on multivariate analysis. Conclusion: The dose-response relationships for the swallowing structures found in these studies suggest that reducing their doses, using either IMRT aimed at their sparing, or brachytherapy, might achieve clinical gains in dysphagia.« less

  8. Dosimetric evaluation of incidental irradiation to the axilla during whole breast radiotherapy for patients with left-sided early breast cancer in the IMRT era.

    PubMed

    Lee, Jayoung; Kim, Shin-Wook; Son, Seok Hyun

    2016-06-01

    The purpose of this study was to compare the dosimetric parameters for incidental irradiation to the axilla during whole breast radiotherapy (WBRT) with 3-dimensional conformal radiotherapy (3D-CRT) and intensity-modulated radiotherapy (IMRT). Twenty left breast cancer patients treated with WBRT after breast-conserving surgery (BCS) were enrolled in this study. Remnant breast tissue, 3 levels of the axilla, heart, and lung were delineated. We used 2 different radiotherapy methods: 3D-CRT with field-in-field technique and 7-field fixed-beam IMRT. The target coverage of IMRT was significantly better than that of 3D-CRT (Dmean: 49.72 ± 0.64 Gy vs 50.24 ± 0.66 Gy, P < 0.001; V45: 93.19 ± 1.40% vs 98.59 ± 0.30%, P < 0.001; V47.5: 86.43 ± 2.72% vs 95.00 ± 0.02%, P < 0.001, for 3D-CRT and IMRT, respectively). In the IMRT plan, a lower dose was delivered to a wider region of the heart and lung. Significantly lower axillary irradiation was shown throughout each level of axilla by IMRT compared to 3D-CRT (Dmean for level I: 42.58 ± 5.31 Gy vs 14.49 ± 6.91 Gy, P < 0.001; Dmean for level II: 26.25 ± 10.43 Gy vs 3.41 ± 3.11 Gy, P < 0.001; Dmean for level III: 6.26 ± 4.69 Gy vs 1.16 ± 0.51 Gy, P < 0.001; Dmean for total axilla: 33.9 ± 6.89 Gy vs 9.96 ± 5.21 Gy, P < 0.001, for 3D-CRT and IMRT, respectively). In conclusion, the incidental dose delivered to the axilla was significantly lower for IMRT compared to 3D-CRT. Therefore, IMRT, which only includes the breast parenchyma, should be cautiously used in patients with limited positive sentinel lymph nodes and who do not undergo complete axillary lymph node dissection.

  9. A non-voxel-based broad-beam (NVBB) framework for IMRT treatment planning.

    PubMed

    Lu, Weiguo

    2010-12-07

    We present a novel framework that enables very large scale intensity-modulated radiation therapy (IMRT) planning in limited computation resources with improvements in cost, plan quality and planning throughput. Current IMRT optimization uses a voxel-based beamlet superposition (VBS) framework that requires pre-calculation and storage of a large amount of beamlet data, resulting in large temporal and spatial complexity. We developed a non-voxel-based broad-beam (NVBB) framework for IMRT capable of direct treatment parameter optimization (DTPO). In this framework, both objective function and derivative are evaluated based on the continuous viewpoint, abandoning 'voxel' and 'beamlet' representations. Thus pre-calculation and storage of beamlets are no longer needed. The NVBB framework has linear complexities (O(N(3))) in both space and time. The low memory, full computation and data parallelization nature of the framework render its efficient implementation on the graphic processing unit (GPU). We implemented the NVBB framework and incorporated it with the TomoTherapy treatment planning system (TPS). The new TPS runs on a single workstation with one GPU card (NVBB-GPU). Extensive verification/validation tests were performed in house and via third parties. Benchmarks on dose accuracy, plan quality and throughput were compared with the commercial TomoTherapy TPS that is based on the VBS framework and uses a computer cluster with 14 nodes (VBS-cluster). For all tests, the dose accuracy of these two TPSs is comparable (within 1%). Plan qualities were comparable with no clinically significant difference for most cases except that superior target uniformity was seen in the NVBB-GPU for some cases. However, the planning time using the NVBB-GPU was reduced many folds over the VBS-cluster. In conclusion, we developed a novel NVBB framework for IMRT optimization. The continuous viewpoint and DTPO nature of the algorithm eliminate the need for beamlets and lead to better plan

  10. Clinical assessment of the jaw-tracking function in IMRT for a brain tumor

    NASA Astrophysics Data System (ADS)

    Kim, Jin-Young; Kim, Shin-Wook; Choe, Bo-Young; Suh, Tae-Suk; Park, Sung-Kwang; Jo, Sun-Mi; Oh, Won-Yong; Shin, Jung-Wook; Cho, Gyu-Seok; Nam, Sang-Hee; Chung, Jin-Beom; Kim, Jung-Ki; Lee, Young-Kyu

    2015-01-01

    Intensity-modulated radiotherapy (IMRT) improves dose conformity and saves critical organs. IMRT is widely used in cases of head and neck, prostate, and brain cancer due to the close location of the targets to critical structures. However, because IMRT has a larger amount of radiation exposure than 3 dimensional-conformal radiation therapy (3D-CRT), it has disadvantages such as increases in the low dose irradiation to normal tissues and in the accumulated dose for the whole volume due to leakage and transmission of the multi-leaf collimator (MLC). The increased accumulated dose and the larger low dose may increase the occurrence of secondary malignant neoplasms. For these reasons, the jaw-tracking function of the TrueBeam (Varian Medical Systems, Palo Alto, CA) was developed to reduce the leakage and the transmission dose of the MLC with linear accelerators. However, the change in the superficial dose has not been verified with a quantitative analysis of the dose reduction in a brain tumor. Therefore, in the present study, we intended to verify the clinical possibility of utilizing the jaw-tracking function for a brain tumor by comparing treatment plans and superficial doses. To accomplish this, we made three types of original treatment plans using Eclipse11 (Varian Medical Systems, Palo Alto, CA): 1) farther than 2 cm from the organs at risk (OAR); 2) within 2 cm of the OAR; and 3) intersecting with the OAR. Jaw-tracking treatment plans were also made with copies of the original treatment plan using Smart LMC Version 11.0.31 (Varian Medical Systems, Palo Alto, CA). A comparison between the original treatment plans and jaw-tracking treatment plans was performed using the difference of the mean dose and maximum dose to the OARs in cumulative Dose Volume Histogram (DVH). In addition, the dependencies of the effects of transmission and the scattering doses according to jaw motion were assessed through the difference in the surface doses. In the DVH comparison, a

  11. SU-F-T-380: Comparing the Effect of Respiration On Dose Distribution Between Conventional Tangent Pair and IMRT Techniques for Adjuvant Radiotherapy in Early Stage Breast Cancer

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wu, M; Ramaseshan, R

    2016-06-15

    Purpose: In this project, we compared the conventional tangent pair technique to IMRT technique by analyzing the dose distribution. We also investigated the effect of respiration on planning target volume (PTV) dose coverage in both techniques. Methods: In order to implement IMRT technique a template based planning protocol, dose constrains and treatment process was developed. Two open fields with optimized field weights were combined with two beamlet optimization fields in IMRT plans. We compared the dose distribution between standard tangential pair and IMRT. The improvement in dose distribution was measured by parameters such as conformity index, homogeneity index and coveragemore » index. Another end point was the IMRT technique will reduce the planning time for staff. The effect of patient’s respiration on dose distribution was also estimated. The four dimensional computed tomography (4DCT) for different phase of breathing cycle was used to evaluate the effect of respiration on IMRT planned dose distribution. Results: We have accumulated 10 patients that acquired 4DCT and planned by both techniques. Based on the preliminary analysis, the dose distribution in IMRT technique was better than conventional tangent pair technique. Furthermore, the effect of respiration in IMRT plan was not significant as evident from the 95% isodose line coverage of PTV drawn on all phases of 4DCT. Conclusion: Based on the 4DCT images, the breathing effect on dose distribution was smaller than what we expected. We suspect that there are two reasons. First, the PTV movement due to respiration was not significant. It might be because we used a tilted breast board to setup patients. Second, the open fields with optimized field weights in IMRT technique might reduce the breathing effect on dose distribution. A further investigation is necessary.« less

  12. Energy modulated electron therapy using a few leaf electron collimator in combination with IMRT and 3D-CRT: Monte Carlo-based planning and dosimetric evaluation

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Al-Yahya, Khalid; Schwartz, Matthew; Shenouda, George

    2005-09-15

    Energy modulated electron therapy (EMET) based on Monte Carlo dose calculation is a promising technique that enhances the treatment planning and delivery of superficially located tumors. This study investigated the application of EMET using a novel few-leaf electron collimator (FLEC) in head and neck and breast sites in comparison with three-dimensional conventional radiation therapy (3D-CRT) and intensity modulated radiation therapy (IMRT) techniques. Treatment planning was performed for two parotid cases and one breast case. Four plans were compared for each case: 3D-CRT, IMRT, 3D-CRT in conjunction with EMET (EMET-CRT), and IMRT in conjunction with EMET (EMET-IMRT), all of which weremore » performed and calculated with Monte Carlo techniques. For all patients, dose volume histograms (DVHs) were obtained for all organs of interest and the DVHs were used as a means of comparing the plans. Homogeneity and conformity of dose distributions were calculated, as well as a sparing index that compares the effect of the low isodose lines. In addition, the whole-body dose equivalent (WBDE) was estimated for each plan. Adding EMET delivered with the FLEC to 3D-CRT improves sparing of normal tissues. For the two head and neck cases, the mean dose to the contralateral parotid and brain stem was reduced relative to IMRT by 43% and 84%, and by 57% and 71%, respectively. Improved normal tissue sparing was quantified as an increase in sparing index of 47% and 30% for the head and neck and the breast cases, respectively. Adding EMET to either 3D-CRT or IMRT results in preservation of target conformity and dose homogeneity. When adding EMET to the treatment plan, the WBDE was reduced by between 6% and 19% for 3D-CRT and by between 21% and 33% for IMRT, while WBDE for EMET-CRT was reduced by up to 72% when compared with IMRT. FLEC offers a practical means of delivering modulated electron therapy. Although adding EMET delivered using the FLEC results in perturbation of target

  13. IMRT plan verification with EBT2 and EBT3 films compared to PTW 2D-ARRAY seven29

    NASA Astrophysics Data System (ADS)

    Hanušová, Tereza; Horáková, Ivana; Koniarová, Irena

    2017-11-01

    The aim of this study was to compare dosimetry with Gafchromic EBT2 and EBT3 films to the ion chamber array PTW seven29 in terms of their performance in clinical IMRT plan verification. A methodology for film processing and calibration was developed. Calibration curves were obtained in MATLAB and in FilmQA Pro. The best calibration curve was then used to calibrate EBT2 and EBT3 films for IMRT plan verification measurements. Films were placed in several coronal planes into an RW3 slab phantom and irradiated with a clinical IMRT plan for prostate and lymph nodes using 18 MV photon beams. Individual fields were tested and irradiated with gantry at 0°. Results were evaluated using gamma analysis with 3%/3 mm criteria in OmniPro I'mRT version 1.7. The same measurements were performed with the ion chamber array PTW seven29 in RW3 slabs (different depths) and in the OCTAVIUS II phantom (isocenter depth only; both original and nominal gantry angles). Results were evaluated in PTW VeriSoft version 3.1 using the same criteria. Altogether, 45 IMRT planes were tested with film and 25 planes with the PTW 2D-ARRAY seven29. Film measuerements showed different results than ion chamber matrix measurements. With PTW 2D-ARRAY seven29, worse results were obtained when the detector was placed into the OCTAVIUS phantom than into the RW3 slab phantom, and the worst pass rates were seen for rotational measurements. EBT2 films showed inconsistent results and could differ significantly for different planes in one field. EBT3 films seemed to give the best results of all the tested configurations.

  14. Evaluating deviations in prostatectomy patients treated with IMRT.

    PubMed

    Sá, Ana Cravo; Peres, Ana; Pereira, Mónica; Coelho, Carina Marques; Monsanto, Fátima; Macedo, Ana; Lamas, Adrian

    2016-01-01

    To evaluate the deviations in prostatectomy patients treated with IMRT in order to calculate appropriate margins to create the PTV. Defining inappropriate margins can lead to underdosing in target volumes and also overdosing in healthy tissues, increasing morbidity. 223 CBCT images used for alignment with the CT planning scan based on bony anatomy were analyzed in 12 patients treated with IMRT following prostatectomy. Shifts of CBCT images were recorded in three directions to calculate the required margin to create PTV. The mean and standard deviation (SD) values in millimetres were -0.05 ± 1.35 in the LR direction, -0.03 ± 0.65 in the SI direction and -0.02 ± 2.05 the AP direction. The systematic error measured in the LR, SI and AP direction were 1.35 mm, 0.65 mm, and 2.05 mm with a random error of 2.07 mm; 1.45 mm and 3.16 mm, resulting in a PTV margin of 4.82 mm; 2.64 mm, and 7.33 mm, respectively. With IGRT we suggest a margin of 5 mm, 3 mm and 8 mm in the LR, SI and AP direction, respectively, to PTV1 and PTV2. Therefore, this study supports an anisotropic margin expansion to the PTV being the largest expansion in the AP direction and lower in SI.

  15. Simultaneous modulated accelerated radiation therapy for esophageal cancer: a feasibility study.

    PubMed

    Zhang, Wu-Zhe; Chen, Jian-Zhou; Li, De-Rui; Chen, Zhi-Jian; Guo, Hong; Zhuang, Ting-Ting; Li, Dong-Sheng; Zhou, Ming-Zhen; Chen, Chuang-Zhen

    2014-10-14

    To establish the feasibility of simultaneous modulated accelerated radiation therapy (SMART) in esophageal cancer (EC). Computed tomography (CT) datasets of 10 patients with upper or middle thoracic squamous cell EC undergoing chemoradiotherapy were used to generate SMART, conventionally-fractionated three-dimensional conformal radiotherapy (3DCRT) and intensity-modulated radiation therapy (cf-IMRT) plans, respectively. The gross target volume (GTV) of the esophagus, positive regional lymph nodes (LN), and suspected lymph nodes (LN ±) were contoured for each patient. The clinical target volume (CTV) was delineated with 2-cm longitudinal and 0.5- to 1.0-cm radial margins with respect to the GTV and with 0.5-cm uniform margins for LN and LN(±). For the SMART plans, there were two planning target volumes (PTVs): PTV66 = (GTV + LN) + 0.5 cm and PTV54 = CTV + 0.5 cm. For the 3DCRT and cf-IMRT plans, there was only a single PTV: PTV60 = CTV + 0.5 cm. The prescribed dose for the SMART plans was 66 Gy/30 F to PTV66 and 54 Gy/30 F to PTV54. The dose prescription to the PTV60 for both the 3DCRT and cf-IMRT plans was set to 60 Gy/30 F. All the plans were generated on the Eclipse 10.0 treatment planning system. Fulfillment of the dose criteria for the PTVs received the highest priority, followed by the spinal cord, heart, and lungs. The dose-volume histograms were compared. Clinically acceptable plans were achieved for all the SMART, cf-IMRT, and 3DCRT plans. Compared with the 3DCRT plans, the SMART plans increased the dose delivered to the primary tumor (66 Gy vs 60 Gy), with improved sparing of normal tissues in all patients. The Dmax of the spinal cord, V20 of the lungs, and Dmean and V50 of the heart for the SMART and 3DCRT plans were as follows: 38.5 ± 2.0 vs 44.7 ± 0.8 (P = 0.002), 17.1 ± 4.0 vs 25.8 ± 5.0 (P = 0.000), 14.4 ± 7.5 vs 21.4 ± 11.1 (P = 0.000), and 4.9 ± 3.4 vs 12.9 ± 7.6 (P = 0.000), respectively. In contrast to the cf-IMRT plans, the SMART plans

  16. Simultaneous modulated accelerated radiation therapy for esophageal cancer: A feasibility study

    PubMed Central

    Zhang, Wu-Zhe; Chen, Jian-Zhou; Li, De-Rui; Chen, Zhi-Jian; Guo, Hong; Zhuang, Ting-Ting; Li, Dong-Sheng; Zhou, Ming-Zhen; Chen, Chuang-Zhen

    2014-01-01

    AIM: To establish the feasibility of simultaneous modulated accelerated radiation therapy (SMART) in esophageal cancer (EC). METHODS: Computed tomography (CT) datasets of 10 patients with upper or middle thoracic squamous cell EC undergoing chemoradiotherapy were used to generate SMART, conventionally-fractionated three-dimensional conformal radiotherapy (3DCRT) and intensity-modulated radiation therapy (cf-IMRT) plans, respectively. The gross target volume (GTV) of the esophagus, positive regional lymph nodes (LN), and suspected lymph nodes (LN±) were contoured for each patient. The clinical target volume (CTV) was delineated with 2-cm longitudinal and 0.5- to 1.0-cm radial margins with respect to the GTV and with 0.5-cm uniform margins for LN and LN(±). For the SMART plans, there were two planning target volumes (PTVs): PTV66 = (GTV + LN) + 0.5 cm and PTV54 = CTV + 0.5 cm. For the 3DCRT and cf-IMRT plans, there was only a single PTV: PTV60 = CTV + 0.5 cm. The prescribed dose for the SMART plans was 66 Gy/30 F to PTV66 and 54 Gy/30 F to PTV54. The dose prescription to the PTV60 for both the 3DCRT and cf-IMRT plans was set to 60 Gy/30 F. All the plans were generated on the Eclipse 10.0 treatment planning system. Fulfillment of the dose criteria for the PTVs received the highest priority, followed by the spinal cord, heart, and lungs. The dose-volume histograms were compared. RESULTS: Clinically acceptable plans were achieved for all the SMART, cf-IMRT, and 3DCRT plans. Compared with the 3DCRT plans, the SMART plans increased the dose delivered to the primary tumor (66 Gy vs 60 Gy), with improved sparing of normal tissues in all patients. The Dmax of the spinal cord, V20 of the lungs, and Dmean and V50 of the heart for the SMART and 3DCRT plans were as follows: 38.5 ± 2.0 vs 44.7 ± 0.8 (P = 0.002), 17.1 ± 4.0 vs 25.8 ± 5.0 (P = 0.000), 14.4 ± 7.5 vs 21.4 ± 11.1 (P = 0.000), and 4.9 ± 3.4 vs 12.9 ± 7.6 (P = 0.000), respectively. In contrast to the cf-IMRT

  17. SU-E-T-472: Improvement of IMRT QA Passing Rate by Correcting Angular Dependence of MatriXX

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Chen, Q; Watkins, W; Kim, T

    2015-06-15

    Purpose: Multi-channel planar detector arrays utilized for IMRT-QA, such as the MatriXX, exhibit an incident-beam angular dependent response which can Result in false-positive gamma-based QA results, especially for helical tomotherapy plans which encompass the full range of beam angles. Although MatriXX can use with gantry angle sensor to provide automatically angular correction, this sensor does not work with tomotherapy. The purpose of the study is to reduce IMRT-QA false-positives by correcting for the MatriXX angular dependence. Methods: MatriXX angular dependence was characterized by comparing multiple fixed-angle irradiation measurements with corresponding TPS computed doses. For 81 Tomo-helical IMRT-QA measurements, two differentmore » correction schemes were tested: (1) A Monte-Carlo dose engine was used to compute MatriXX signal based on the angular-response curve. The computed signal was then compared with measurement. (2) Uncorrected computed signal was compared with measurements uniformly scaled to account for the average angular dependence. Three scaling factor (+2%, +2.5%, +3%) were tested. Results: The MatriXX response is 8% less than predicted for a PA beam even when the couch is fully accounted for. Without angular correction, only 67% of the cases pass the >90% points γ<1 (3%, 3mm). After full angular correction, 96% of the cases pass the criteria. Of three scaling factors, +2% gave the highest passing rate (89%), which is still less than the full angular correction method. With a stricter γ(2%,3mm) criteria, the full angular correction method was still able to achieve the 90% passing rate while the scaling method only gives 53% passing rate. Conclusion: Correction for the MatriXX angular dependence reduced the false-positives rate of our IMRT-QA process. It is necessary to correct for the angular dependence to achieve the IMRT passing criteria specified in TG129.« less

  18. Multicentre validation of IMRT pre-treatment verification: comparison of in-house and external audit.

    PubMed

    Jornet, Núria; Carrasco, Pablo; Beltrán, Mercè; Calvo, Juan Francisco; Escudé, Lluís; Hernández, Victor; Quera, Jaume; Sáez, Jordi

    2014-09-01

    We performed a multicentre intercomparison of IMRT optimisation and dose planning and IMRT pre-treatment verification methods and results. The aims were to check consistency between dose plans and to validate whether in-house pre-treatment verification results agreed with those of an external audit. Participating centres used two mock cases (prostate and head and neck) for the intercomparison and audit. Compliance to dosimetric goals and total number of MU per plan were collected. A simple quality index to compare the different plans was proposed. We compared gamma index pass rates using the centre's equipment and methodology to those of an external audit. While for the prostate case, all centres fulfilled the dosimetric goals and plan quality was homogeneous, that was not the case for the head and neck case. The number of MU did not correlate with the plan quality index. Pre-treatment verifications results of the external audit did not agree with those of the in-house measurements for two centres: being within tolerance for in-house measurements and unacceptable for the audit or the other way round. Although all plans fulfilled dosimetric constraints, plan quality is highly dependent on the planner expertise. External audits are an excellent tool to detect errors in IMRT implementation and cannot be replaced by intercomparison using results obtained by centres. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  19. SU-F-T-395: Evaluation of Best Dosimetry Achievable with VMAT and IMRT Treatment Techniques Targeting Borderline Resectable Pancreatic Cancer

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Harpool, K; Schnell, E; Herman, T

    Purpose: To determine from retrospective study the most appropriate technique for targeting small borderline operable pancreatic cancer surrounding blood vessels by evaluating the dosimetry and normal tissue sparing achievable using Volumetric Modulated Arc Therapy (VMAT) and Intensity Modulated Radiation Therapy (IMRT). Methods: Treatment plans from ten patients who have undergone treatment with a prescribed dose of 4950 cGy, at 275 cGy per fraction, were analyzed. All plans were replanned using Eclipse TPS (Varian Medical Systems, Palo Alto, CA) with complementary VMAT or IMRT techniques to obtain paired data sets for comparison. The coverage to at least 95% of the plannedmore » target volume (PTV) was normalized to receive 100% of the prescription dose. The normal tissue constraints followed the quantitative analysis of normal tissue effects in the clinic (QUANTEC) guidelines and the organs at risks (OARs) were liver, kidneys, spinal cord and bowel. The plan evaluation was based on conformity index (CI), homogeneity index (HI), uniformity index (UI), DVH parameters, and student’s-t statistics (2 tails). Results: The VMAT technique delivered less maximum dose to the right kidney, left kidney, total kidney, liver, spinal cord, and bowel by 9.3%, 5.9%, 6.7%, 3.9%, 15.1%, 3.9%, and 4.3%, respectively. The averaged V15 for the total kidney was 10.21% for IMRT and 7.29% for VMAT. The averaged V20 for the bowel was 19.89% for IMRT and 14.06% for VMAT. On average, the CI for IMRT was 1.20 and 1.16 for VMAT (p = 0.20). The HI was 0.08 for both techniques (p = 0.91) and UI was 1.05 and 1.06 for IMRT and VMAT respectively (p = 0.59). Conclusion: Both techniques achieve adequate PTV coverage. Although VMAT techniques show better normal tissue sparing from excessive dose, no significant differences were observed. Slight discrepancies may rise from different versions of calculation algorithms.« less

  20. SU-E-T-365: Dosimetric Impact of Dental Amalgam CT Image Artifacts On IMRT and VMAT Head and Neck Plans

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Cao, N; Young, L; Parvathaneni, U

    Purpose: The presence of high density dental amalgam in patient CT image data sets causes dose calculation errors for head and neck (HN) treatment planning. This study assesses and compares dosimetric variations in IMRT and VMAT treatment plans due to dental artifacts. Methods: Sixteen HN patients with similar treatment sites (oropharynx), tumor volume and extensive dental artifacts were divided into two groups: IMRT (n=8, 6 to 9 beams) and VMAT (n=8, 2 arcs with 352° rotation). All cases were planned with the Pinnacle 9.2 treatment planning software using the collapsed cone convolution superposition algorithm and a range of prescription dosemore » from 60 to 72Gy. Two different treatment plans were produced, each based on one of two image sets: (a)uncorrected; (b)dental artifacts density overridden (set to 1.0g/cm{sup 3}). Differences between the two treatment plans for each of the IMRT and VMAT techniques were quantified by the following dosimetric parameters: maximum point dose, maximum spinal cord and brainstem dose, mean left and right parotid dose, and PTV coverage (V95%Rx). Average differences generated for these dosimetric parameters were compared between IMRT and VMAT plans. Results: The average absolute dose differences (plan a minus plan b) for the VMAT and IMRT techniques, respectively, caused by dental artifacts were: 2.2±3.3cGy vs. 37.6±57.5cGy (maximum point dose, P=0.15); 1.2±0.9cGy vs. 7.9±6.7cGy (maximum spinal cord dose, P=0.026); 2.2±2.4cGy vs. 12.1±13.0cGy (maximum brainstem dose, P=0.077); 0.9±1.1cGy vs. 4.1±3.5cGy (mean left parotid dose, P=0.038); 0.9±0.8cGy vs. 7.8±11.9cGy (mean right parotid dose, P=0.136); 0.021%±0.014% vs. 0.803%±1.44% (PTV coverage, P=0.17). Conclusion: For the HN plans studied, dental artifacts demonstrated a greater dose calculation error for IMRT plans compared to VMAT plans. Rotational arcs appear on the average to compensate dose calculation errors induced by dental artifacts. Thus, compared to VMAT

  1. A dosimetric comparison of 3D-CRT, IMRT, and static tomotherapy with an SIB for large and small breast volumes

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Michalski, Andrea; Central Coast Cancer Centre, Gosford Hospital, Gosford, New South Wales; Atyeo, John, E-mail: john.atyeo@sydney.edu.au

    2014-07-01

    Radiation therapy to the breast is a complex task, with many different techniques that can be employed to ensure adequate dose target coverage while minimizing doses to the organs at risk. This study compares the dose planning outcomes of 3 radiation treatment modalities, 3 dimensional conformal radiation therapy (3D-CRT), intensity-modulated radiation therapy (IMRT), and static tomotherapy, for left-sided whole-breast radiation treatment with a simultaneous integrated boost (SIB). Overall, 20 patients with left-sided breast cancer were separated into 2 cohorts, small and large, based on breast volume. Dose plans were produced for each patient using 3D-CRT, IMRT, and static tomotherapy. Allmore » patients were prescribed a dose of 45 Gy in 20 fractions to the breast with an SIB of 56 Gy in 20 fractions to the tumor bed and normalized so that D{sub 98%} > 95% of the prescription dose. Dosimetric comparisons were made between the 3 modalities and the interaction of patient size. All 3 modalities offered adequate planning target volume (PTV) coverage with D{sub 98%} > 95% and D{sub 2%} < 107%. Static tomotherapy offered significantly improved (p = 0.006) dose homogeneity to the PTV{sub boost} {sub eval} (0.079 ± 0.011) and breast minus the SIB volume (Breast{sub SIB}) (p < 0.001, 0.15 ± 0.03) compared with the PTV{sub boost} {sub eval} (0.085 ± 0.008, 0.088 ± 0.12) and Breast{sub SIB} (0.22 ± 0.05, 0.23 ± 0.03) for IMRT and 3D-CRT, respectively. Static tomotherapy also offered statistically significant reductions (p < 0.001) in doses to the ipsilateral lung mean dose of 6.79 ± 2.11 Gy compared with 7.75 ± 2.54 Gy and 8.29 ± 2.76 Gy for IMRT and 3D-CRT, respectively, and significantly (p < 0.001) reduced heart doses (mean = 2.83 ± 1.26 Gy) compared to both IMRT and 3D-CRT (mean = 3.70 ± 1.44 Gy and 3.91 ± 1.58 Gy). Static tomotherapy is the dosimetrically superior modality for the whole breast with an SIB compared with IMRT and 3D-CRT. IMRT is superior to

  2. Expert consensus contouring guidelines for IMRT in esophageal and gastroesophageal junction cancer

    PubMed Central

    Wu, Abraham J.; Bosch, Walter R.; Chang, Daniel T.; Hong, Theodore S.; Jabbour, Salma K.; Kleinberg, Lawrence R.; Mamon, Harvey J.; Thomas, Charles R.; Goodman, Karyn A.

    2015-01-01

    Purpose/Objective(s) Current guidelines for esophageal cancer contouring are derived from traditional two-dimensional fields based on bony landmarks, and do not provide sufficient anatomical detail to ensure consistent contouring for more conformal radiotherapy techniques such as intensity-modulated radiation therapy (IMRT). Therefore, we convened an expert panel with the specific aim to derive contouring guidelines and generate an atlas for the clinical target volume (CTV) in esophageal or gastroesophageal junction (GEJ) cancer. Methods and Materials Eight expert academically-based gastrointestinal radiation oncologists participated. Three sample cases were chosen: a GEJ cancer, a distal esophageal cancer, and a mid-upper esophageal cancer. Uniform CT simulation datasets and an accompanying diagnostic PET-CT were distributed to each expert, and he/she was instructed to generate gross tumor volume (GTV) and CTV contours for each case. All contours were aggregated and subjected to quantitative analysis to assess the degree of concordance between experts and generate draft consensus contours. The panel then refined these contours to generate the contouring atlas. Results Kappa statistics indicated substantial agreement between panelists for each of the three test cases. A consensus CTV atlas was generated for the three test cases, each representing common anatomic presentations of esophageal cancer. The panel agreed on guidelines and principles to facilitate the generalizability of the atlas to individual cases. Conclusions This expert panel successfully reached agreement on contouring guidelines for esophageal and GEJ IMRT and generated a reference CTV atlas. This atlas will serve as a reference for IMRT contours for clinical practice and prospective trial design. Subsequent patterns of failure analyses of clinical datasets utilizing these guidelines may require modification in the future. PMID:26104943

  3. Propensity score based comparison of long term outcomes with 3D conformal radiotherapy (3DCRT) versus Intensity Modulated Radiation Therapy (IMRT) in the treatment of esophageal cancer

    PubMed Central

    Lin, Steven H.; Wang, Lu; Myles, Bevan; Thall, Peter F.; Hofstetter, Wayne L.; Swisher, Stephen G.; Ajani, Jaffer A.; Cox, James D.; Komaki, Ritsuko; Liao, Zhongxing

    2014-01-01

    Purpose Although 3DCRT is the worldwide standard for the treatment of esophageal cancers, IMRT improves dose conformality and reduces radiation exposure to normal tissues. We hypothesized that the dosimetric advantages of IMRT should translate to substantive benefits in clinical outcomes compared to 3DCRT. Methods and Materials Analysis was performed on 676 nonrandomized patients (3DCRT=413, IMRT=263) with stage Ib-IVa (AJCC 2002) esophageal cancers treated with chemoradiation at a single institution from 1998–2008. An inverse probability of treatment weighting (IPW) and inclusion of propensity score (treatment probability) as a covariate were used to compare overall survival (OS) time, time to local failure, and time to distant metastasis, while accounting for effects of other clinically relevant covariates. Propensity scores were estimated using logistic regression. Results A fitted multivariate inverse probability weighted (IPW)-adjusted Cox model showed that OS time was significantly associated with several well-known prognostic factors, along with radiation modality (IMRT vs 3DCRT, HR=0.72, p<0.001). Compared to IMRT, 3DCRT patients had a significantly greater risk of dying (72.6% vs 52.9%, IPW log rank test: p<0.0001) and for local-regional recurrence (LRR) (p=0.0038). There was no difference in cancer-specific mortality (Gray’s test, p=0.86), or distant metastasis (p=0.99) between the two groups. An increased cumulative incidence of cardiac deaths was seen in the 3DCRT group (p=0.049), but most deaths were undocumented (5 year estimate: 11.7% in 3DCRT vs 5.4% in IMRT, Gray’s test, p=0.0029). Conclusions Overall survival, locoregional control, and non-cancer related deaths were significantly better for IMRT compared to 3DCRT. Although these results need confirmation, IMRT should be considered for the treatment of esophageal cancer. PMID:22867894

  4. SU-F-T-522: Dosimetric Study of Junction Dose in Double Isocenter Flatten and Flatten Filter Free IMRT and VMAT Plan Delivery

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Samuvel, K; Yadav, G; Bhushan, M

    2016-06-15

    Purpose: To quantify the dosimetric accuracy of junction dose in double isocenter flattened and flatten filter free(FFF) intensity modulated radiation therapy(IMRT) and volumetric modulated arc therapy(VMAT) plan delivery using pelvis phantom. Methods: Five large field pelvis patients were selected for this study. Double isocenter IMRT and VMAT treatment plans were generated in Eclipse Treatment planning System (V.11.0) using 6MV FB and FFF beams. For all the plans same distance 17.0cm was kept between one isocenter to another isocenter. IMRT Plans were made with 7 coplanar fields and VMAT plans were made with full double arcs. Dose calculation was performed usingmore » AAA algorithms with dose grid size of 0.25 cm. Verification plans were calculated on Scanditronix Wellhofer pelvis slab phantom. Measurement point was selected and calculated, where two isocenter plan fields are overlapping, this measurement point was kept at distance 8.5cm from both isocenter. The plans were delivered using Varian TrueBeamTM machine on pelvis slab phantom. Point dose measurements was carried out using CC13 ion chamber volume of 0.13cm3. Results: The measured junction point dose are compared with TPS calculated dose. The mean difference observed was 4.5%, 6.0%, 4.0% and 7.0% for IMRT-FB,IMRT-FFF, VMAT-FB and VMAT-FFF respectively. The measured dose results shows closer agreement with calculated dose in Flatten beam planning in both IMRT and VMAT, whereas in FFF beam plan dose difference are more compared with flatten beam plan. Conclusion: Dosimetry accuracy of Large Field junction dose difference was found less in Flatten beam compared with FFF beam plan delivery. Even though more dosimetric studies are required to analyse junction dose for FFF beam planning using multiple point dose measurements and fluence map verification in field junction area.« less

  5. Characterization and clinical evaluation of a novel 2D detector array for conventional and flattening filter free (FFF) IMRT pre-treatment verification.

    PubMed

    Sekar, Yuvaraj; Thoelking, Johannes; Eckl, Miriam; Kalichava, Irakli; Sihono, Dwi Seno Kuncoro; Lohr, Frank; Wenz, Frederik; Wertz, Hansjoerg

    2018-04-01

    The novel MatriXX FFF (IBA Dosimetry, Germany) detector is a new 2D ionization chamber detector array designed for patient specific IMRT-plan verification including flattening-filter-free (FFF) beams. This study provides a detailed analysis of the characterization and clinical evaluation of the new detector array. The verification of the MatriXX FFF was subdivided into (i) physical dosimetric tests including dose linearity, dose rate dependency and output factor measurements and (ii) patient specific IMRT pre-treatment plan verifications. The MatriXX FFF measurements were compared to the calculated dose distribution of a commissioned treatment planning system by gamma index and dose difference evaluations for 18 IMRT-sequences. All IMRT-sequences were measured with original gantry angles and with collapsing all beams to 0° gantry angle to exclude the influence of the detector's angle dependency. The MatriXX FFF was found to be linear and dose rate independent for all investigated modalities (deviations ≤0.6%). Furthermore, the output measurements of the MatriXX FFF were in very good agreement to reference measurements (deviations ≤1.8%). For the clinical evaluation an average pixel passing rate for γ (3%,3mm) of (98.5±1.5)% was achieved when applying a gantry angle correction. Also, with collapsing all beams to 0° gantry angle an excellent agreement to the calculated dose distribution was observed (γ (3%,3mm) =(99.1±1.1)%). The MatriXX FFF fulfills all physical requirements in terms of dosimetric accuracy. Furthermore, the evaluation of the IMRT-plan measurements showed that the detector particularly together with the gantry angle correction is a reliable device for IMRT-plan verification including FFF. Copyright © 2017. Published by Elsevier GmbH.

  6. Dosimetric Verification of IMRT Treatment Plans Using an Electronic Portal Imaging Device

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kruszyna, Marta

    This paper presents the procedures and results of dosimetric verification using an Electronic Portal Imaging Device as a tool for pre-treatment dosimetry in IMRT technique at the Greater Poland Cancer Centre in Poznan, Poland. The evaluation of dosimetric verification for various organ, during a 2 year period is given.

  7. Poster — Thur Eve — 33: The Influence of a Modeled Treatment Couch on Dose Distributions During IMRT and RapidArc Treatment Delivery

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Aldosary, Ghada; Nobah, Ahmad; Al-Zorkani, Faisal

    2014-08-15

    Treatment couches have been known to perturb dose delivery in patients. This effect is most pronounced in techniques such as IMRT and RapidArc. Although modern treatment planning systems (TPS) include data for a “default” treatment couch, actual couches are not manufactured identically. Thus, variations in their Hounsfield Unit (HU) values may exist. This study demonstrates a practical and simple method of acquiring reliable HU data for any treatment couch. We also investigate the effects of both the default and modeled treatment couches on absorbed dose. Experimental verifications show that by neglecting to incorporate the treatment couch in the TPS, dosemore » differences of up to 9.5% and 7.3% were present for 4 MV and 10 MV photon beams, respectively. Furthermore, a clinical study based on a cohort of 20 RapidArc and IMRT (brain, pelvis and abdominal) cases is performed. 2D dose distributions show that without the couch in the planning phase, differences ≤ 4.6% and 5.9% for RapidArc and IMRT cases are present for the same cases that the default couch was added to. Additionally, in comparison to the default couch, employing the modeled couch in the calculation process influences dose distributions by ≤ 2.7% and 8% for RapidArc and IMRT cases, respectively. This result was found to be site specific; where an accurate couch proves to be preferable for IMRT brain plans. As such, adding the couch during dose calculation decreases dose calculation errors, and a precisely modeled treatment couch offers higher dose delivery accuracy for brain treatment using IMRT.« less

  8. A two‐point scheme for optimal breast IMRT treatment planning

    PubMed Central

    2013-01-01

    We propose an approach to determining optimal beam weights in breast/chest wall IMRT treatment plans. The goal is to decrease breathing effect and to maximize skin dose if the skin is included in the target or, otherwise, to minimize the skin dose. Two points in the target are utilized to calculate the optimal weights. The optimal plan (i.e., the plan with optimal beam weights) consists of high energy unblocked beams, low energy unblocked beams, and IMRT beams. Six breast and five chest wall cases were retrospectively planned with this scheme in Eclipse, including one breast case where CTV was contoured by the physician. Compared with 3D CRT plans composed of unblocked and field‐in‐field beams, the optimal plans demonstrated comparable or better dose uniformity, homogeneity, and conformity to the target, especially at beam junction when supraclavicular nodes are involved. Compared with nonoptimal plans (i.e., plans with nonoptimized weights), the optimal plans had better dose distributions at shallow depths close to the skin, especially in cases where breathing effect was taken into account. This was verified with experiments using a MapCHECK device attached to a motion simulation table (to mimic motion caused by breathing). PACS number: 87.55 de PMID:24257291

  9. Comparison of testicular dose delivered by intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT) in patients with prostate cancer

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Martin, Jeffrey M.; Handorf, Elizabeth A.; Price, Robert A.

    A small decrease in testosterone level has been documented after prostate irradiation, possibly owing to the incidental dose to the testes. Testicular doses from prostate external beam radiation plans with either intensity-modulated radiation therapy (IMRT) or volumetric-modulated arc therapy (VMAT) were calculated to investigate any difference. Testicles were contoured for 16 patients being treated for localized prostate cancer. For each patient, 2 plans were created: 1 with IMRT and 1 with VMAT. No specific attempt was made to reduce testicular dose. Minimum, maximum, and mean doses to the testicles were recorded for each plan. Of the 16 patients, 4 receivedmore » a total dose of 7800 cGy to the prostate alone, 7 received 8000 cGy to the prostate alone, and 5 received 8000 cGy to the prostate and pelvic lymph nodes. The mean (range) of testicular dose with an IMRT plan was 54.7 cGy (21.1 to 91.9) and 59.0 cGy (25.1 to 93.4) with a VMAT plan. In 12 cases, the mean VMAT dose was higher than the mean IMRT dose, with a mean difference of 4.3 cGy (p = 0.019). There was a small but statistically significant increase in mean testicular dose delivered by VMAT compared with IMRT. Despite this, it unlikely that there is a clinically meaningful difference in testicular doses from either modality.« less

  10. WE-AB-202-04: Statistical Evaluation of Lung Function Using 4DCT Ventilation Imaging: Proton Therapy VS IMRT

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Huang, Q; Zhang, M; Chen, T

    Purpose: Variation in function of different lung regions has been ignored so far for conventional lung cancer treatment planning, which may lead to higher risk of radiation induced lung disease. 4DCT based lung ventilation imaging provides a novel yet convenient approach for lung functional imaging as 4DCT is taken as routine for lung cancer treatment. Our work aims to evaluate the impact of accounting for spatial heterogeneity in lung function using 4DCT based lung ventilation imaging for proton and IMRT plans. Methods: Six patients with advanced stage lung cancer of various tumor locations were retrospectively evaluated for the study. Protonmore » and IMRT plans were designed following identical planning objective and constrains for each patient. Ventilation images were calculated from patients’ 4DCT using deformable image registration implemented by Velocity AI software based on Jacobian-metrics. Lung was delineated into two function level regions based on ventilation (low and high functional area). High functional region was defined as lung ventilation greater than 30%. Dose distribution and statistics in different lung function area was calculated for patients. Results: Variation in dosimetric statistics of different function lung region was observed between proton and IMRT plans. In all proton plans, high function lung regions receive lower maximum dose (100.2%–108.9%), compared with IMRT plans (106.4%–119.7%). Interestingly, three out of six proton plans gave higher mean dose by up to 2.2% than IMRT to high function lung region. Lower mean dose (lower by up to 14.1%) and maximum dose (lower by up to 9%) were observed in low function lung for proton plans. Conclusion: A systematic approach was developed to generate function lung ventilation imaging and use it to evaluate plans. This method hold great promise in function analysis of lung during planning. We are currently studying more subjects to evaluate this tool.« less

  11. A Phase II Study of Preradiotherapy Chemotherapy Followed by Hyperfractionated Radiotherapy for Newly Diagnosed High-Risk Medulloblastoma/Primitive Neuroectodermal Tumor: A Report From the Children's Oncology Group (CCG 9931)

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Allen, Jeffrey; Donahue, Bernadine; Mehta, Minesh

    2009-07-15

    Purpose: To verify feasibility and monitor progression-free survival and overall survival in children with high-risk medulloblastoma and noncerebellar primitive neuroectodermal tumors (PNETs) treated in a Phase II study with preradiotherapy chemotherapy (CHT) followed by high-dose, hyperfractionated craniospinal radiotherapy (CSRT). Methods and Materials: Eligibility criteria included age >3 years at diagnosis, medulloblastoma with either high M stage and/or >1.5 cm{sup 2} postoperative residual disease, and all patients with noncerebellar PNET. Treatment was initiated with five alternating monthly cycles of CHT (A [cisplatin, cyclophosphamide, etoposide, and vincristine], B [carboplatin and etoposide], A, B, and A) followed by hyperfractionated CSRT (40 Gy) withmore » a boost to the primary tumor (72 Gy) given in twice-daily 1-Gy fractions. Results: The valid study group consisted of 124 patients whose median age at diagnosis was 7.8 years. Eighty-four patients (68%) completed the entire protocol according to study guidelines (within 9 months), and the median time to complete CSRT was 1.6 months. Major reasons for failure to complete CHT included progressive disease (17%) and toxic death (2.4%). The 5-year progression-free survival and overall survival rates were 43% {+-} 5% and 52% {+-} 5%, respectively. No significant differences were detected in subset analysis related to response to CHT, site of primary tumor, postoperative residual disease, or M stage. Conclusions: The feasibility of this intensive multimodality protocol was confirmed, and response to pre-RT CHT did not impact on survival. Survival data from this protocol can not be compared with data from other studies, given the protocol design.« less

  12. Prostate Dose Escalation by Innovative Inverse Planning-Driven IMRT

    DTIC Science & Technology

    2006-11-01

    fLJ and at each step, we find the minimizer u,\\ of J’. The Euler-Lagrange equation for the regularized J’ functional is u- div ( 1 Vu )= f E S1,2A...GD, Agazaryan N, Solberg TD . 2003. The effects of tumor motion on planning and delivery of respiratory-gated IMRT. Med Phys 30:1052-1066. Jaffray DA...modulated) radiation therapy: a review. Phys Med Biol 51 :R403-425. Wink NM, McNitt-Gray MF, Solberg TD . 2005. Optimization of multi-slice helical

  13. Virtual EPID standard phantom audit (VESPA) for remote IMRT and VMAT credentialing

    NASA Astrophysics Data System (ADS)

    Miri, Narges; Lehmann, Joerg; Legge, Kimberley; Vial, Philip; Greer, Peter B.

    2017-06-01

    A virtual EPID standard phantom audit (VESPA) has been implemented for remote auditing in support of facility credentialing for clinical trials using IMRT and VMAT. VESPA is based on published methods and a clinically established IMRT QA procedure, here extended to multi-vendor equipment. Facilities are provided with comprehensive instructions and CT datasets to create treatment plans. They deliver the treatment directly to their EPID without any phantom or couch in the beam. In addition, they deliver a set of simple calibration fields per instructions. Collected EPID images are uploaded electronically. In the analysis, the dose is projected back into a virtual cylindrical phantom. 3D gamma analysis is performed. 2D dose planes and linear dose profiles are provided and can be considered when needed for clarification. In addition, using a virtual flat-phantom, 2D field-by-field or arc-by-arc gamma analyses are performed. Pilot facilities covering a range of planning and delivery systems have performed data acquisition and upload successfully. Advantages of VESPA are (1) fast turnaround mainly driven by the facility’s capability of providing the requested EPID images, (2) the possibility for facilities performing the audit in parallel, as there is no need to wait for a phantom, (3) simple and efficient credentialing for international facilities, (4) a large set of data points, and (5) a reduced impact on resources and environment as there is no need to transport heavy phantoms or audit staff. Limitations of the current implementation of VESPA for trials credentialing are that it does not provide absolute dosimetry, therefore a Level I audit is still required, and that it relies on correctly delivered open calibration fields, which are used for system calibration. The implemented EPID based IMRT and VMAT audit system promises to dramatically improve credentialing efficiency for clinical trials and wider applications.

  14. Dose planning objectives in anal canal cancer IMRT: the TROG ANROTAT experience

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Brown, Elizabeth, E-mail: elizabeth@mebrown.net; Cray, Alison; Haworth, Annette

    2015-06-15

    Intensity modulated radiotherapy (IMRT) is ideal for anal canal cancer (ACC), delivering high doses to irregular tumour volumes whilst minimising dose to surrounding normal tissues. Establishing achievable dose objectives is a challenge. The purpose of this paper was to utilise data collected in the Assessment of New Radiation Oncology Treatments and Technologies (ANROTAT) project to evaluate the feasibility of ACC IMRT dose planning objectives employed in the Australian situation. Ten Australian centres were randomly allocated three data sets from 15 non-identifiable computed tomography data sets representing a range of disease stages and gender. Each data set was planned by twomore » different centres, producing 30 plans. All tumour and organ at risk (OAR) contours, prescription and dose constraint details were provided. Dose–volume histograms (DVHs) for each plan were analysed to evaluate the feasibility of dose planning objectives provided. All dose planning objectives for the bone marrow (BM) and femoral heads were achieved. Median planned doses exceeded one or more objectives for bowel, external genitalia and bladder. This reached statistical significance for bowel V30 (P = 0.04), V45 (P < 0.001), V50 (P < 0.001), external genitalia V20 (P < 0.001) and bladder V35 (P < 0.001), V40 (P = 0.01). Gender was found to be the only significant factor in the likelihood of achieving the bowel V50 (P = 0.03) and BM V30 constraints (P = 0.04). The dose planning objectives used in the ANROTAT project provide a good starting point for ACC IMRT planning. To facilitate clinical implementation, it is important to prioritise OAR objectives and recognise factors that affect the achievability of these objectives.« less

  15. Virtual EPID standard phantom audit (VESPA) for remote IMRT and VMAT credentialing.

    PubMed

    Miri, Narges; Lehmann, Joerg; Legge, Kimberley; Vial, Philip; Greer, Peter B

    2017-06-07

    A virtual EPID standard phantom audit (VESPA) has been implemented for remote auditing in support of facility credentialing for clinical trials using IMRT and VMAT. VESPA is based on published methods and a clinically established IMRT QA procedure, here extended to multi-vendor equipment. Facilities are provided with comprehensive instructions and CT datasets to create treatment plans. They deliver the treatment directly to their EPID without any phantom or couch in the beam. In addition, they deliver a set of simple calibration fields per instructions. Collected EPID images are uploaded electronically. In the analysis, the dose is projected back into a virtual cylindrical phantom. 3D gamma analysis is performed. 2D dose planes and linear dose profiles are provided and can be considered when needed for clarification. In addition, using a virtual flat-phantom, 2D field-by-field or arc-by-arc gamma analyses are performed. Pilot facilities covering a range of planning and delivery systems have performed data acquisition and upload successfully. Advantages of VESPA are (1) fast turnaround mainly driven by the facility's capability of providing the requested EPID images, (2) the possibility for facilities performing the audit in parallel, as there is no need to wait for a phantom, (3) simple and efficient credentialing for international facilities, (4) a large set of data points, and (5) a reduced impact on resources and environment as there is no need to transport heavy phantoms or audit staff. Limitations of the current implementation of VESPA for trials credentialing are that it does not provide absolute dosimetry, therefore a Level I audit is still required, and that it relies on correctly delivered open calibration fields, which are used for system calibration. The implemented EPID based IMRT and VMAT audit system promises to dramatically improve credentialing efficiency for clinical trials and wider applications.

  16. In vivo dose verification of IMRT treated head and neck cancer patients.

    PubMed

    Engström, Per E; Haraldsson, Pia; Landberg, Torsten; Sand Hansen, Hanne; Aage Engelholm, Svend; Nyström, Håkan

    2005-01-01

    An independent in vivo dose verification procedure for IMRT treatments of head and neck cancers was developed. Results of 177 intracavitary TLD measurements from 10 patients are presented. The study includes data from 10 patients with cancer of the rhinopharynx or the thyroid treated with dynamic IMRT. Dose verification was performed by insertion of a flexible naso-oesophageal tube containing TLD rods and markers for EPID and simulator image detection. Part of the study focussed on investigating the accuracy of the TPS calculations in the presence of inhomogeneities. Phantom measurements and Monte Carlo simulations were performed for a number of geometries involving lateral electronic disequilibrium and steep density shifts. The in vivo TLD measurements correlated well with the predictions of the treatment planning system with a measured/calculated dose ratio of 1.002+/-0.051 (1 SD, N=177). The measurements were easily performed and well tolerated by the patients. We conclude that in vivo intracavitary dosimetry with TLD is suitable and accurate for dose determination in intensity-modulated beams.

  17. Correction of respiratory motion for IMRT using aperture adaptive technique and visual guidance: A feasibility study

    NASA Astrophysics Data System (ADS)

    Chen, Ho-Hsing; Wu, Jay; Chuang, Keh-Shih; Kuo, Hsiang-Chi

    2007-07-01

    Intensity-modulated radiation therapy (IMRT) utilizes nonuniform beam profile to deliver precise radiation doses to a tumor while minimizing radiation exposure to surrounding normal tissues. However, the problem of intrafraction organ motion distorts the dose distribution and leads to significant dosimetric errors. In this research, we applied an aperture adaptive technique with a visual guiding system to toggle the problem of respiratory motion. A homemade computer program showing a cyclic moving pattern was projected onto the ceiling to visually help patients adjust their respiratory patterns. Once the respiratory motion becomes regular, the leaf sequence can be synchronized with the target motion. An oscillator was employed to simulate the patient's breathing pattern. Two simple fields and one IMRT field were measured to verify the accuracy. Preliminary results showed that after appropriate training, the amplitude and duration of volunteer's breathing can be well controlled by the visual guiding system. The sharp dose gradient at the edge of the radiation fields was successfully restored. The maximum dosimetric error in the IMRT field was significantly decreased from 63% to 3%. We conclude that the aperture adaptive technique with the visual guiding system can be an inexpensive and feasible alternative without compromising delivery efficiency in clinical practice.

  18. [The Dose Effect of Isocenter Selection during IMRT Dose Verification with the 2D Chamber Array].

    PubMed

    Xie, Chuanbin; Cong, Xiaohu; Xu, Shouping; Dai, Xiangkun; Wang, Yunlai; Han, Lu; Gong, Hanshun; Ju, Zhongjian; Ge, Ruigang; Ma, Lin

    2015-03-01

    To investigate the dose effect of isocenter difference during IMRT dose verification with the 2D chamber array. The samples collected from 10 patients were respectively designed for IMRT plans, the isocenter of which was independently defined as P(o), P(x) and P(y). P(o) was fixed on the target center and the other points shifted 8cm from the target center in the orientation of x/y. The PTW729 was used for 2D dose verification in the 3 groups which beams of plans were set to 0 degrees. The γ-analysis passing rates for the whole plan and each beam were gotten using the different standards in the 3 groups, The results showed the mean passing rate of γ-analysis was highest in the P(o) group, and the mean passing rate of the whole plan was better than that of each beam. In addition, it became worse with the increase of dose leakage between the leaves in P(y) group. Therefore, the determination of isocenter has a visible effect for IMRT dose verification of the 2D chamber array, The isocenter of the planning design should be close to the geometric center of target.

  19. Reducing Xerostomia After Chemo-IMRT for Head and Neck Cancer: Beyond Sparing the Parotid Glands

    PubMed Central

    Little, Michael; Schipper, Matthew; Feng, Felix Y.; Vineberg, Karen; Cornwall, Craig; Murdoch-Kinch, Carol-Anne; Eisbruch, Avraham

    2011-01-01

    Purpose To assess whether in addition to sparing parotid glands (PGs), xerostomia after chemo-IMRT of head and neck cancer is affected by reducing doses to other salivary glands. Methods Prospective study: 78 patients with stages III/IV oropharynx/nasopharynx cancers received chemo-IMRT aiming to spare the parts outside the targets of bilateral PGs, oral cavity (OC) containing the minor salivary glands, and contralateral submandibular gland (SMG) (when contralateral level I was not a target). Pretherapy and periodically through 24 months, validated patient-reported xerostomia questionnaires (XQ) scores and observer-graded xerostomia were recorded, and stimulated and unstimulated saliva measured selectively from each of the PGs and SMGs. Mean OC doses served as surrogates of minor salivary glands dysfunction. Regression models assessed XQ and observer-graded xerostomia predictors. Results Statistically significant predictors of the XQ score in univariate analysis included OC, PG, and SMG mean doses, as well as baseline XQ score, time since RT, and both stimulated and unstimulated PG saliva flow rates. Similar factors were statistically significant predictors of observer-graded xerostomia. OC, PG and SMG mean doses were moderately inter-correlated (r=0.47–0.55). In multivariate analyses, after adjusting for PG and SMG doses, OC mean dose (p < 0.0001), time from RT (p < 0.0001), and stimulated PG saliva (p < 0.0025) were significant predictors for XQ scores, and OC mean dose and time for observer-graded xerostomia. While scatter plots showed no thresholds, OC mean doses <40 Gy and contralateral SMG mean <50 Gy were each associated with low patient-reported and observer-rated xerostomia at almost all post-therapy time points. Conclusion PG, SMG and OC mean doses were significant predictors of both patient-reported and observer-rated xerostomia after chemo-IMRT, with OC doses remaining significant after adjusting for PG and SMG doses. These results support efforts to

  20. Advantages and limitations of navigation-based multicriteria optimization (MCO) for localized prostate cancer IMRT planning

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    McGarry, Conor K., E-mail: conor.mcgarry@belfasttrust.hscni.net; Bokrantz, Rasmus; RaySearch Laboratories, Stockholm

    2014-10-01

    Efficacy of inverse planning is becoming increasingly important for advanced radiotherapy techniques. This study’s aims were to validate multicriteria optimization (MCO) in RayStation (v2.4, RaySearch Laboratories, Sweden) against standard intensity-modulated radiation therapy (IMRT) optimization in Oncentra (v4.1, Nucletron BV, the Netherlands) and characterize dose differences due to conversion of navigated MCO plans into deliverable multileaf collimator apertures. Step-and-shoot IMRT plans were created for 10 patients with localized prostate cancer using both standard optimization and MCO. Acceptable standard IMRT plans with minimal average rectal dose were chosen for comparison with deliverable MCO plans. The trade-off was, for the MCO plans, managedmore » through a user interface that permits continuous navigation between fluence-based plans. Navigated MCO plans were made deliverable at incremental steps along a trajectory between maximal target homogeneity and maximal rectal sparing. Dosimetric differences between navigated and deliverable MCO plans were also quantified. MCO plans, chosen as acceptable under navigated and deliverable conditions resulted in similar rectal sparing compared with standard optimization (33.7 ± 1.8 Gy vs 35.5 ± 4.2 Gy, p = 0.117). The dose differences between navigated and deliverable MCO plans increased as higher priority was placed on rectal avoidance. If the best possible deliverable MCO was chosen, a significant reduction in rectal dose was observed in comparison with standard optimization (30.6 ± 1.4 Gy vs 35.5 ± 4.2 Gy, p = 0.047). Improvements were, however, to some extent, at the expense of less conformal dose distributions, which resulted in significantly higher doses to the bladder for 2 of the 3 tolerance levels. In conclusion, similar IMRT plans can be created for patients with prostate cancer using MCO compared with standard optimization. Limitations exist within MCO regarding conversion of navigated plans to

  1. SU-F-T-296: Modulated Therapy Down Under: A Survey of IMRT & VMAT Physics Practice in Australia and New Zealand

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Barber, J; School of Physics, University of Sydney; Vial, P

    Purpose: A comprehensive survey of Australasian radiation oncology physics departments was undertaken to capture a snapshot of current usage, commissioning and QA practices for intensity-modulated therapies. Methods: An online survey was developed and advertised to Australian and New Zealand radiation oncology physicists through the local college (ACPSEM) in April 2015. The survey consisted of 147 questions in total, covering IMRT, VMAT and Tomotherapy, and details specific to different treatment planning systems. Questions captured detailed information on equipment, policies and procedures for the commissioning and QA of each treatment technique. Results: 41 partial or complete responses were collected, representing 59 departmentsmore » out of the 78 departments operational. 137 and 84 linacs from these departments were using IMRT and VMAT respectively, from a total 150 linacs. 100% and 78% of respondents were treating with IMRT and VMAT respectively. There are at least 8 different treatment planning systems being used for IMRT or VMAT, and large variations in all aspects of QA policies and procedures. 29 responses indicated 72 methods routinely used for pre-treatment QA, when breaking down by device and analysis type. Similar numbers of departments use field-by-field analysis compared to composite analysis (56% to 44%) while a majority use true gantry angle delivery compared to fixed gantry at 0° (72% to 28%). 19 different implementations of gamma index analysis parameters were reported from 33 responses. A follow-up one-day workshop to highlight the results, discuss the role of QA and share equipment-specific knowledge across users was conducted in November 2015. Conclusion: While IMRT and VMAT are almost universally available in Australasia, large variations in practice indicate a need for national or consensus guidelines.« less

  2. VMAT vs. 7-Field-IMRT: Assessing the Dosimetric Parameters of Prostate Cancer Treatment with a 292-Patient Sample

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kopp, Robert W.; Duff, Michael, E-mail: mduff@cancercarewny.com; Catalfamo, Frank

    2011-01-01

    We compared normal tissue radiation dose for the treatment of prostate cancer using 2 different radiation therapy delivery methods: volumetric modulated arc therapy (VMAT) vs. fixed-field intensity-modulated radiation therapy (IMRT). Radiotherapy plans for 292 prostate cancer patients treated with VMAT to a total dose of 7740 cGy were analyzed retrospectively. Fixed-angle, 7-field IMRT plans were created using the same computed tomography datasets and contours. Radiation doses to the planning target volume (PTV) and organs at risk (bladder, rectum, penile bulb, and femoral heads) were measured, means were calculated for both treatment methods, and dose-volume comparisons were made with 2-tailed, pairedmore » t-tests. The mean dose to the bladder was lower with VMAT at all measured volumes: 5, 10, 15, 25, 35, and 50% (p < 0.05). The mean doses to 5 and 10% of the rectum, the high-dose regions, were lower with VMAT (p < 0.05). The mean dose to 15% of the rectal volume was not significantly different (p = 0.95). VMAT exposed larger rectal volumes (25, 35, and 50%) to more radiation than fixed-field IMRT (p < 0.05). Average mean dose to the penile bulb (p < 0.05) and mean dose to 10% of the femoral heads (p < 0.05) were lower with VMAT. VMAT therapy for prostate cancer has dosimetric advantages for critical structures, notably for high-dose regions compared with fixed-field IMRT, without compromising PTV coverage. This may translate into reduced acute and chronic toxicity.« less

  3. MRI-based IMRT planning for MR-linac: comparison between CT- and MRI-based plans for pancreatic and prostate cancers

    NASA Astrophysics Data System (ADS)

    Prior, Phil; Chen, Xinfeng; Botros, Maikel; Paulson, Eric S.; Lawton, Colleen; Erickson, Beth; Li, X. Allen

    2016-05-01

    The treatment planning in radiation therapy (RT) can be arranged to combine benefits of computed tomography (CT) and magnetic resonance imaging (MRI) together to maintain dose calculation accuracy and improved target delineation. Our aim is study the dosimetric impact of uniform relative electron density assignment on IMRT treatment planning with additional consideration given to the effect of a 1.5 T transverse magnetic field (TMF) in MR-Linac. A series of intensity modulated RT (IMRT) plans were generated for two representative tumor sites, pancreas and prostate, using CT and MRI datasets. Representative CT-based IMRT plans were generated to assess the impact of different electron density (ED) assignment on plan quality using CT without the presence of a 1.5 T TMF. The relative ED (rED) values used were taken from the ICRU report 46. Four types of rED assignment in the organs at risk (OARs), the planning target volumes (PTV) and in the non-specified tissue (NST) were considered. Dose was recalculated (no optimization) using a Monaco 5.09.07a research planning system employing Monte Carlo calculations with an option to include TMF. To investigate the dosimetric effect of different rED assignment, the dose-volume parameters (DVPs) obtained from these specific rED plans were compared to those obtained from the original plans based on CT. Overall, we found that uniform rED assignment results in differences in DVPs within 3% for the PTV and 5% for OAR. The presence of 1.5 T TMF on IMRT DVPs resulted in differences that were generally within 3% of the Gold St for both the pancreas and prostate. The combination of uniform rED assignment and TMF produced differences in DVPs that were within 4-5% of the Gold St. Larger differences in DVPs were observed for OARs on T2-based plans. The effects of using different rED assignments and the presence of 1.5 T TMF for pancreas and prostate IMRT plans are generally within 3% and 5% of PTV and OAR Gold St values. There are

  4. Dosimetric Predictors of Radiation-induced Acute Nausea and Vomiting in IMRT for Nasopharyngeal Cancer

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Lee, Victor H.F., E-mail: vhflee@hku.hk; Ng, Sherry C.Y.; Leung, T.W.

    Purpose: We wanted to investigate dosimetric parameters that would predict radiation-induced acute nausea and vomiting in intensity-modulated radiation therapy (IMRT) for undifferentiated carcinoma of the nasopharynx (NPC). Methods and Materials: Forty-nine consecutive patients with newly diagnosed NPC were treated with IMRT alone in this prospective study. Patients receiving any form of chemotherapy were excluded. The dorsal vagal complex (DVC) as well as the left and right vestibules (VB-L and VB-R, respectively) were contoured on planning computed tomography images. A structure combining both the VB-L and the VB-R, named VB-T, was also generated. All structures were labeled organs at risk (OAR).more » A 3-mm three-dimensional margin was added to these structures and labeled DVC+3 mm, VB-L+3 mm, VB-R+3 mm, and VB-T+3 mm to account for physiological body motion and setup error. No weightings were given to these structures during optimization in treatment planning. Dosimetric parameters were recorded from dose-volume histograms. Statistical analysis of parameters' association with nausea and vomiting was performed using univariate and multivariate logistic regression. Results: Six patients (12.2%) reported Grade 1 nausea, and 8 patients (16.3%) reported Grade 2 nausea. Also, 4 patients (8.2%) complained of Grade 1 vomiting, and 4 patients (8.2%) experienced Grade 2 vomiting. No patients developed protracted nausea and vomiting after completion of IMRT. For radiation-induced acute nausea, V40 (percentage volume receiving at least 40Gy) to the VB-T and V40>=80% to the VB-T were predictors, using univariate analysis. On multivariate analysis, V40>=80% to the VB-T was the only predictor. There were no predictors of radiation-induced acute vomiting, as the number of events was too small for analysis. Conclusions: This is the first study demonstrating that a V40 to the VB-T is predictive of radiation-induced acute nausea. The vestibules should be labeled as sensitive

  5. TH-A-9A-02: BEST IN PHYSICS (THERAPY) - 4D IMRT Planning Using Highly- Parallelizable Particle Swarm Optimization

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Modiri, A; Gu, X; Sawant, A

    2014-06-15

    Purpose: We present a particle swarm optimization (PSO)-based 4D IMRT planning technique designed for dynamic MLC tracking delivery to lung tumors. The key idea is to utilize the temporal dimension as an additional degree of freedom rather than a constraint in order to achieve improved sparing of organs at risk (OARs). Methods: The target and normal structures were manually contoured on each of the ten phases of a 4DCT scan acquired from a lung SBRT patient who exhibited 1.5cm tumor motion despite the use of abdominal compression. Corresponding ten IMRT plans were generated using the Eclipse treatment planning system. Thesemore » plans served as initial guess solutions for the PSO algorithm. Fluence weights were optimized over the entire solution space i.e., 10 phases × 12 beams × 166 control points. The size of the solution space motivated our choice of PSO, which is a highly parallelizable stochastic global optimization technique that is well-suited for such large problems. A summed fluence map was created using an in-house B-spline deformable image registration. Each plan was compared with a corresponding, internal target volume (ITV)-based IMRT plan. Results: The PSO 4D IMRT plan yielded comparable PTV coverage and significantly higher dose—sparing for parallel and serial OARs compared to the ITV-based plan. The dose-sparing achieved via PSO-4DIMRT was: lung Dmean = 28%; lung V20 = 90%; spinal cord Dmax = 23%; esophagus Dmax = 31%; heart Dmax = 51%; heart Dmean = 64%. Conclusion: Truly 4D IMRT that uses the temporal dimension as an additional degree of freedom can achieve significant dose sparing of serial and parallel OARs. Given the large solution space, PSO represents an attractive, parallelizable tool to achieve globally optimal solutions for such problems. This work was supported through funding from the National Institutes of Health and Varian Medical Systems. Amit Sawant has research funding from Varian Medical Systems, VisionRT Ltd. and Elekta.« less

  6. Impact of Salivary Gland Dosimetry on Post-IMRT Recovery of Saliva Output and Xerostomia Grade for Head-and-Neck Cancer Patients Treated With or Without Contralateral Submandibular Gland Sparing: A Longitudinal Study

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wang Zhonghe; Yan Chao; Zhang Zhiyuan

    Purpose: To observe the recovery of saliva output and effect on xerostomia grade after intensity-modulated radiotherapy (IMRT) with or without contralateral submandibular gland (cSMG) sparing and to assess the impact of salivary gland dosimetry on this recovery among patients with head-and-neck cancer. Methods and Materials: Between May 2007 and May 2008, 52 patients with head-and-neck cancer received definitive (n = 5 patients) and postoperative (n = 47 patients) IMRT at our institution, with at least one parotid gland spared. Of these patients, 26 patients with a low risk of recurrence in the cSMG region underwent IMRT and had their cSMGsmore » spared (cSMG-sparing group). The remaining 26 high-risk patients had no cSMGs spared (cSMG-unspared group). Xerostomia grades and salivary flow rates were monitored at five time points (before IMRT and at 2, 6, 12, and 18 months after IMRT). Results: Average mean doses and mean volumes receiving 30 Gy (V30) of the cSMGs were lower in the cSMG-sparing group than in the cSMG-unspared group (mean dose, 20.4 Gy vs. 57.4 Gy; mean V30, 14.7% vs. 99.8%, respectively). Xerostomia grades at 2 and 6 months post-IMRT were also significantly lower among patients in the cSMG-sparing group than in the cSMG-unspared group, but differences were not significant at 12 and 18 months after IMRT. Patients in the cSMG-sparing group had significantly better mean unstimulated salivary flow rates at each time point post- IMRT as well as better mean stimulated salivary flow rates at 2 months post-IMRT. Conclusions: Recovery of saliva output and grade of xerostomia post-IMRT in patients whose cSMGs were spared were much better than in patients whose cSMGs were not spared. The influence of the mean doses to the cSMG and parotid gland on the recovery of saliva output was equivalent to that of the mean V30 to the glands.« less

  7. Examination of the properties of IMRT and VMAT beams and evaluation against pre-treatment quality assurance results

    NASA Astrophysics Data System (ADS)

    Crowe, S. B.; Kairn, T.; Middlebrook, N.; Sutherland, B.; Hill, B.; Kenny, J.; Langton, C. M.; Trapp, J. V.

    2015-03-01

    This study aimed to provide a detailed evaluation and comparison of a range of modulated beam evaluation metrics, in terms of their correlation with QA testing results and their variation between treatment sites, for a large number of treatments. Ten metrics including the modulation index (MI), fluence map complexity, modulation complexity score (MCS), mean aperture displacement (MAD) and small aperture score (SAS) were evaluated for 546 beams from 122 intensity modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT) treatment plans targeting the anus, rectum, endometrium, brain, head and neck and prostate. The calculated sets of metrics were evaluated in terms of their relationships to each other and their correlation with the results of electronic portal imaging based quality assurance (QA) evaluations of the treatment beams. Evaluation of the MI, MAD and SAS suggested that beams used in treatments of the anus, rectum, head and neck were more complex than the prostate and brain treatment beams. Seven of the ten beam complexity metrics were found to be strongly correlated with the results from QA testing of the IMRT beams (p < 0.00008). For example, values of SAS (with multileaf collimator apertures narrower than 10 mm defined as ‘small’) less than 0.2 also identified QA passing IMRT beams with 100% specificity. However, few of the metrics are correlated with the results from QA testing of the VMAT beams, whether they were evaluated as whole 360° arcs or as 60° sub-arcs. Select evaluation of beam complexity metrics (at least MI, MCS and SAS) is therefore recommended, as an intermediate step in the IMRT QA chain. Such evaluation may also be useful as a means of periodically reviewing VMAT planning or optimiser performance.

  8. Phase II Study of Long-Term Androgen Suppression With Bevacizumab and Intensity-Modulated Radiation Therapy (IMRT) in High-Risk Prostate Cancer

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Vuky, Jacqueline, E-mail: vukyja@ohsu.edu; Pham, Huong T.; Warren, Sarah

    Purpose: We report a Phase II trial assessing the acute and late toxicities of intensity-modulated radiation therapy (IMRT), long-term androgen suppression (LTAS), and bevacizumab in patients with high-risk localized prostate cancer. Methods and Materials: We treated 18 patients with LTAS with bicalutamide and goserelin in combination with bevacizumab and IMRT. Bevacizumab (10 mg/kg every 2 weeks) was administered for the first 16 weeks, and 15 mg/kg was then given every 3 weeks for 12 additional weeks, with an IMRT dose of 77.9 Gy to the prostate, 64.6 Gy to the seminal vesicles, and 57 Gy to the pelvic lymph nodes.more » Patients were eligible if they had clinical stage T2b to T4, a Gleason sum score of 8 to 10, or a prostate- specific antigen level of 20ng/mL or greater. The primary endpoint of the study was evaluation of acute and late toxicities. Results: The median age was 69 years, with a median pretreatment prostate-specific antigen level of 12.5 ng/mL and Gleason score of 8. The pretreatment clinical stage was T1c in 4 patients, T2 in 11, and T3 in 3. All patients completed IMRT with median follow-up of 34 months (range, 28-40 months) The most common Grade 2 or higher toxicities were hypertension (61% of patients with Grade 2 and 11% with Grade 3), proteinuria (28% with Grade 2 and 6% with Grade 3), and leucopenia (28% with Grade 2). No Grade 4 or higher acute toxicities were reported. Late toxicities included proctitis (6% of patients with Grade 2 and 11% with Grade 3), rectal bleeding (6% with Grade 2 and 11% with Grade 3), hematuria (6% with Grade 2), proteinuria (17% with Grade 2), hyponatremia (6% with Grade 3), cystitis (6% with Grade 3), and urinary retention (6% with Grade 2 and 11% with Grade 3). Grade 4 prostatitis occurred in 1 patient (6%). Conclusions: Bevacizumab does not appear to exacerbate the acute effects of IMRT. Late toxicities may have been worsened with this regimen. Further investigations of bevacizumab with LTAS and IMRT should

  9. Estimate of the risk of radiation-induced cancers after linear-accelerator-based breast-cancer radiotherapy

    NASA Astrophysics Data System (ADS)

    Koh, Eui Kwan; Seo, Jungju; Baek, Tae Seong; Chung, Eun Ji; Yoon, Myonggeun; Lee, Hyun-ho

    2013-07-01

    The aim of this study is to assess and compare the excess absolute risks (EARs) of radiation-induced cancers following conformal (3D-CRT), fixed-field intensity-modulated (IMRT) and volumetric modulated arc (RapidArc) radiation therapy in patients with breast cancer. 3D-CRT, IMRT and RapidArc were planned for 10 breast cancer patients. The organ-specific EAR for cancer induction was estimated using the organ equivalent dose (OED) based on computed dose volume histograms (DVHs) and the secondary doses measured at various points from the field edge. The average secondary dose per Gy treatment dose from 3D-CRT, measured 10 to 50 cm from the field edge, ranged from 8.27 to 1.04 mGy. The secondary doses per Gy from IMRT and RapidArc, however, ranged between 5.86 and 0.54 mGy, indicating that IMRT and RapidArc are associated with smaller doses of secondary radiation than 3D-CRT. The organ specific EARs for out-of-field organs, such as the thyroid, liver and colon, were higher with 3D-CRT than with IMRT or RapidArc. In contrast, EARs for in-field organs were much lower with 3D-CRT than with IMRT or RapidArc. The overall estimate of EAR indicated that the radiation-induced cancer risk was 1.8-2.0 times lower with 3D-CRT than with IMRT or RapidArc. Comparisons of EARs during breast irradiation suggested that the predicted risk of secondary cancers was lower with 3D-CRT than with IMRT or RapidArc.

  10. Evaluation of Dosimetry Check software for IMRT patient-specific quality assurance.

    PubMed

    Narayanasamy, Ganesh; Zalman, Travis; Ha, Chul S; Papanikolaou, Niko; Stathakis, Sotirios

    2015-05-08

    The purpose of this study is to evaluate the use of the Dosimetry Check system for patient-specific IMRT QA. Typical QA methods measure the dose in an array dosimeter surrounded by homogenous medium for which the treatment plan has been recomputed. With the Dosimetry Check system, fluence measurements acquired on a portal dosimeter is applied to the patient's CT scans. Instead of making dose comparisons in a plane, Dosimetry Check system produces isodose lines and dose-volume histograms based on the planning CT images. By exporting the dose distribution from the treatment planning system into the Dosimetry Check system, one is able to make a direct comparison between the calculated dose and the planned dose. The versatility of the software is evaluated with respect to the two IMRT techniques - step and shoot and volumetric arc therapy. The system analyzed measurements made using EPID, PTW seven29, and IBA MatriXX, and an intercomparison study was performed. Plans from patients previously treated at our institution with treated anatomical site on brain, head & neck, liver, lung, and prostate were analyzed using Dosimetry Check system for any anatomical site dependence. We have recommendations and possible precautions that may be necessary to ensure proper QA with the Dosimetry Check system.

  11. Sensitivity of an Elekta iView GT a-Si EPID model to delivery errors for pre-treatment verification of IMRT fields.

    PubMed

    Herwiningsih, Sri; Hanlon, Peta; Fielding, Andrew

    2014-12-01

    A Monte Carlo model of an Elekta iViewGT amorphous silicon electronic portal imaging device (a-Si EPID) has been validated for pre-treatment verification of clinical IMRT treatment plans. The simulations involved the use of the BEAMnrc and DOSXYZnrc Monte Carlo codes to predict the response of the iViewGT a-Si EPID model. The predicted EPID images were compared to the measured images obtained from the experiment. The measured EPID images were obtained by delivering a photon beam from an Elekta Synergy linac to the Elekta iViewGT a-Si EPID. The a-Si EPID was used with no additional build-up material. Frame averaged EPID images were acquired and processed using in-house software. The agreement between the predicted and measured images was analyzed using the gamma analysis technique with acceptance criteria of 3 %/3 mm. The results show that the predicted EPID images for four clinical IMRT treatment plans have a good agreement with the measured EPID signal. Three prostate IMRT plans were found to have an average gamma pass rate of more than 95.0 % and a spinal IMRT plan has the average gamma pass rate of 94.3 %. During the period of performing this work a routine MLC calibration was performed and one of the IMRT treatments re-measured with the EPID. A change in the gamma pass rate for one field was observed. This was the motivation for a series of experiments to investigate the sensitivity of the method by introducing delivery errors, MLC position and dosimetric overshoot, into the simulated EPID images. The method was found to be sensitive to 1 mm leaf position errors and 10 % overshoot errors.

  12. Optimal field-splitting algorithm in intensity-modulated radiotherapy: Evaluations using head-and-neck and female pelvic IMRT cases

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Dou, Xin; Kim, Yusung, E-mail: yusung-kim@uiowa.edu; Bayouth, John E.

    2013-04-01

    To develop an optimal field-splitting algorithm of minimal complexity and verify the algorithm using head-and-neck (H and N) and female pelvic intensity-modulated radiotherapy (IMRT) cases. An optimal field-splitting algorithm was developed in which a large intensity map (IM) was split into multiple sub-IMs (≥2). The algorithm reduced the total complexity by minimizing the monitor units (MU) delivered and segment number of each sub-IM. The algorithm was verified through comparison studies with the algorithm as used in a commercial treatment planning system. Seven IMRT, H and N, and female pelvic cancer cases (54 IMs) were analyzed by MU, segment numbers, andmore » dose distributions. The optimal field-splitting algorithm was found to reduce both total MU and the total number of segments. We found on average a 7.9 ± 11.8% and 9.6 ± 18.2% reduction in MU and segment numbers for H and N IMRT cases with an 11.9 ± 17.4% and 11.1 ± 13.7% reduction for female pelvic cases. The overall percent (absolute) reduction in the numbers of MU and segments were found to be on average −9.7 ± 14.6% (−15 ± 25 MU) and −10.3 ± 16.3% (−3 ± 5), respectively. In addition, all dose distributions from the optimal field-splitting method showed improved dose distributions. The optimal field-splitting algorithm shows considerable improvements in both total MU and total segment number. The algorithm is expected to be beneficial for the radiotherapy treatment of large-field IMRT.« less

  13. SU-E-T-430: Modeling MLC Leaf End in 2D for Sliding Window IMRT and Arc Therapy

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Liang, X; Zhu, T

    2014-06-01

    Purpose: To develop a 2D geometric model for MLC accounting for leaf end dose leakage for dynamic IMRT and Rapidarc therapy. Methods: Leaf-end dose leakage is one of the problems for MLC dose calculation and modeling. Dosimetric leaf gap used to model the MLC and to count for leakage in dose calculation, but may not be accurate for smaller leaf gaps. We propose another geometric modeling method to compensate for the MLC round-shape leaf ends dose leakage, and improve the accuracy of dose calculation and dose verification. A triangular function is used to geometrically model the MLC leaf end leakagemore » in the leaf motion direction, and a step function is used in the perpendicular direction. Dose measurements with different leaf gap, different window width, and different window height were conducted, and the results were used to fit the analytical model to get the model parameters. Results: Analytical models have been obtained for stop-and-shoot and dynamic modes for MLC motion. Parameters a=0.4, lw'=5.0 mm for 6X and a=0.54, lw'=4.1 mm for 15x were obtained from the fitting process. The proposed MLC leaf end model improves the dose profile at the two ends of the sliding window opening. This improvement is especially significant for smaller sliding window openings, which are commonly used for highly modulated IMRT plans and arc therapy plans. Conclusion: This work models the MLC round leaf end shape and movement pattern for IMRT dose calculation. The theory, as well as the results in this work provides a useful tool for photon beam IMRT dose calculation and verification.« less

  14. Phase I study of icotinib, an EGFR tyrosine kinase inhibitor combined with IMRT in nasopharyngeal carcinoma.

    PubMed

    Hu, Wei; Wang, Wei; Yang, Peinong; Zhou, Chao; Yang, Weifang; Wu, Bo; Lu, Hongsheng; Yang, Haihua

    2015-01-01

    Epidermal growth factor receptor (EGFR) is a new target for nasopharyngeal carcinoma (NPC) therapy. This prospective phase I study sought to determine the safety and recommended phase II dose of icotinib, a novel highly selective oral EGFR tyrosine kinase inhibitor, in combination with intensity-modulated radiotherapy (IMRT) in patients with NPC. Eligible patients with NPC received escalating doses of icotinib during IMRT. We treated six patients at a particular dose level until the maximum tolerated dose (MTD) was determined. The starting dose was 125 mg, once-daily and the dose was escalated to another level 125 mg, twice- and thrice- daily, until dose-limiting toxicity (DLT) occurred in two or more patients at a dose level. Expression and mutation analysis of EGFR were performed in all cases. A total of twelve patients were enrolled. Three patients experienced DLT (250 mg/day cohort) and MTD was 125 mg/day. Mucositis toxicity appears to be the major DLT. While EGFR expression in tumor tissue was detected in 75% (9/12) patients, EGFR mutation was detected in 16.67% (1/6) patients in 125 mg/day cohort, and 50% (3/6) in 250 mg/day cohort. The combination of icotinib (125 mg/day) and IMRT in patients with locally NPC had an acceptable safety profile and was well tolerated.

  15. Treatment of Children With Central Nervous System Primitive Neuroectodermal Tumors/Pinealoblastomas in the Prospective Multicentric Trial HIT 2000 Using Hyperfractionated Radiation Therapy Followed by Maintenance Chemotherapy

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Gerber, Nicolas U., E-mail: nicolas.gerber@kispi.uzh.ch; Hoff, Katja von; Resch, Anika

    Purpose: The prognosis for children with central nervous system primitive neuroectodermal tumor (CNS-PNET) or pinealoblastoma is still unsatisfactory. Here we report the results of patients between 4 and 21 years of age with nonmetastatic CNS-PNET or pinealoblastoma diagnosed from January 2001 to December 2005 and treated in the prospective GPOH-trial P-HIT 2000-AB4. Methods and Materials: After surgery, children received hyperfractionated radiation therapy (36 Gy to the craniospinal axis, 68 Gy to the tumor region, and 72 Gy to any residual tumor, fractionated at 2 × 1 Gy per day 5 days per week) accompanied by weekly intravenous administration of vincristine and followed by 8 cycles of maintenance chemotherapy (lomustine, cisplatin, andmore » vincristine). Results: Twenty-six patients (15 with CNS-PNET; 11 with pinealoblastoma) were included. Median age at diagnosis was 11.5 years old (range, 4.0-20.7 years). Gross total tumor resection was achieved in 6 and partial resection in 16 patients (indistinct, 4 patients). Median follow-up of the 15 surviving patients was 7.0 years (range, 5.2-10.0 years). The combined response rate to postoperative therapy was 17 of 20 (85%). Eleven of 26 patients (42%; 7 of 15 with CNS-PNET; 4 of 11 with pinealoblastoma) showed tumor progression or relapse at a median time of 1.3 years (range, 0.5-1.9 years). Five-year progression-free and overall survival rates (±standard error [SE]) were each 58% (±10%) for the entire cohort: CNS-PNET was 53% (±13); pinealoblastoma was 64% (±15%; P=.524 and P=.627, respectively). Conclusions: Postoperative hyperfractionated radiation therapy with local dose escalation followed by maintenance chemotherapy was feasible without major acute toxicity. Survival rates are comparable to those of a few other recent studies but superior to those of most other series, including the previous trial, HIT 1991.« less

  16. A Prospective Trial of Intensity Modulated Radiation Therapy (IMRT) Incorporating a Simultaneous Integrated Boost for Prostate Cancer: Long-term Outcomes Compared With Standard Image Guided IMRT

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Schild, Michael H.; Schild, Steven E., E-mail: sschild@mayo.edu; Wong, William W.

    Purpose: This report describes the long-term outcomes of a prospective trial of intensity modulated radiation therapy (IMRT), integrating a {sup 111}In capromab pendetide (ProstaScint) scan-directed simultaneous integrated boost (SIB) for localized prostate cancer. Methods and Materials: Seventy-one patients with T1N0M0 to T4N0M0 prostate cancer were enrolled, and their ProstaScint and pelvic computed tomography scans were coregistered for treatment planning. The entire prostate received 75.6 Gy in 42 fractions with IMRT, whereas regions of increased uptake on ProstaScint scans received 82 Gy as an SIB. Patients with intermediate- and high-risk disease also received 6 months and 12 months of adjuvant hormonal therapy, respectively. Results: The studymore » enrolled 31 low-, 30 intermediate-, and 10 high-risk patients. The median follow-up was 120 months (range, 24-150 months). The 10-year biochemical control rates were 85% for the entire cohort and 84%, 84%, and 90% for patients with low-, intermediate-, and high-risk disease, respectively. The 10-year survival rate of the entire cohort was 69%. Pretreatment prostate-specific antigen level >10 ng/mL and boost volume of >10% of the prostate volume were significantly associated with poorer biochemical control and survival. The outcomes were compared with those of a cohort of 302 patients treated similarly but without the SIB and followed up for a median of 91 months (range, 6-138 months). The 5- and 10-year biochemical control rates were 86% and 61%, respectively, in patients without the SIB compared with 94% and 85%, respectively, in patients in this trial who received the SIB (P=.02). The cohort that received an SIB did not have increased toxicity. Conclusions: The described IMRT strategy, integrating multiple imaging modalities to administer 75.6 Gy to the entire prostate with a boost dose of 82 Gy, was feasible. The addition of the SIB was associated with greater biochemical control but not toxicity

  17. The dosimetric effects of tissue heterogeneities in intensity-modulated radiation therapy (IMRT) of the head and neck

    NASA Astrophysics Data System (ADS)

    Al-Hallaq, H. A.; Reft, C. S.; Roeske, J. C.

    2006-03-01

    The dosimetric effects of bone and air heterogeneities in head and neck IMRT treatments were quantified. An anthropomorphic RANDO phantom was CT-scanned with 16 thermoluminescent dosimeter (TLD) chips placed in and around the target volume. A standard IMRT plan generated with CORVUS was used to irradiate the phantom five times. On average, measured dose was 5.1% higher than calculated dose. Measurements were higher by 7.1% near the heterogeneities and by 2.6% in tissue. The dose difference between measurement and calculation was outside the 95% measurement confidence interval for six TLDs. Using CORVUS' heterogeneity correction algorithm, the average difference between measured and calculated doses decreased by 1.8% near the heterogeneities and by 0.7% in tissue. Furthermore, dose differences lying outside the 95% confidence interval were eliminated for five of the six TLDs. TLD doses recalculated by Pinnacle3's convolution/superposition algorithm were consistently higher than CORVUS doses, a trend that matched our measured results. These results indicate that the dosimetric effects of air cavities are larger than those of bone heterogeneities, thereby leading to a higher delivered dose compared to CORVUS calculations. More sophisticated algorithms such as convolution/superposition or Monte Carlo should be used for accurate tailoring of IMRT dose in head and neck tumours.

  18. Quantifying the interplay effect in prostate IMRT delivery using a convolution-based method.

    PubMed

    Li, Haisen S; Chetty, Indrin J; Solberg, Timothy D

    2008-05-01

    The authors present a segment-based convolution method to account for the interplay effect between intrafraction organ motion and the multileaf collimator position for each particular segment in intensity modulated radiation therapy (IMRT) delivered in a step-and-shoot manner. In this method, the static dose distribution attributed to each segment is convolved with the probability density function (PDF) of motion during delivery of the segment, whereas in the conventional convolution method ("average-based convolution"), the static dose distribution is convolved with the PDF averaged over an entire fraction, an entire treatment course, or even an entire patient population. In the case of IMRT delivered in a step-and-shoot manner, the average-based convolution method assumes that in each segment the target volume experiences the same motion pattern (PDF) as that of population. In the segment-based convolution method, the dose during each segment is calculated by convolving the static dose with the motion PDF specific to that segment, allowing both intrafraction motion and the interplay effect to be accounted for in the dose calculation. Intrafraction prostate motion data from a population of 35 patients tracked using the Calypso system (Calypso Medical Technologies, Inc., Seattle, WA) was used to generate motion PDFs. These were then convolved with dose distributions from clinical prostate IMRT plans. For a single segment with a small number of monitor units, the interplay effect introduced errors of up to 25.9% in the mean CTV dose compared against the planned dose evaluated by using the PDF of the entire fraction. In contrast, the interplay effect reduced the minimum CTV dose by 4.4%, and the CTV generalized equivalent uniform dose by 1.3%, in single fraction plans. For entire treatment courses delivered in either a hypofractionated (five fractions) or conventional (> 30 fractions) regimen, the discrepancy in total dose due to interplay effect was negligible.

  19. SU-E-T-618: Dosimetric Comparison of Manual and Beam Angle Optimization of Gantry Angles in IMRT for Cervical Cancer

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Lin, X; Sun, T; Liu, T

    2014-06-01

    Purpose: To evaluate the dosimetric characteristics of intensity-modulated radiotherapy (IMRT) treatment plan with beam angle optimization. Methods: Ten post-operation patients with cervical cancer were included in this analysis. Two IMRT plans using seven beams were designed in each patient. A standard coplanar equi-space beam angles were used in the first plan (plan 1), whereas the selection of beam angle was optimized by beam angle optimization algorithm in Varian Eclipse treatment planning system for the same number of beams in the second plan (plan 2). Two plans were designed for each patient with the same dose-volume constraints and prescription dose. Allmore » plans were normalized to the mean dose to PTV. The dose distribution in the target, the dose to the organs at risk and total MU were compared. Results: For conformity and homogeneity in PTV, no statistically differences were observed in the two plans. For the mean dose in bladder, plan 2 were significantly lower than plan 1(p<0.05). No statistically significant differences were observed between two plans for the mean doses in rectum, left and right femur heads. Compared with plan1, the average monitor units reduced 16% in plan 2. Conclusion: The IMRT plan based on beam angle optimization for cervical cancer could reduce the dose delivered to bladder and also reduce MU. Therefore there were some dosimetric advantages in the IMRT plan with beam angle optimization for cervical cancer.« less

  20. Assessment of quality of life in patients treated with accelerated radiotherapy for laryngeal and hypopharyngeal carcinomas.

    PubMed

    Allal, A S; Dulguerov, P; Bieri, S; Lehmann, W; Kurtz, J M

    2000-05-01

    This study was conducted to evaluate quality of life (QOL) and functional outcome in patients with carcinomas of the larynx and hypopharynx treated with accelerated radiotherapy (RT). Between January 1991 and September 1996, 21 patients treated with accelerated concomitant boost RT schedule (69.9 Gy in 5. 5 weeks) for laryngeal (n = 10) or hypopharyngeal (n = 11) carcinomas and who remained free of disease at 1-year minimum follow-up were evaluated. The functional outcome was assessed by the subjective Performance Status Scale for Head and Neck cancer (PSSHN) and general QOL by the European Organization for Research and Treatment of Cancer Core QOL questionnaire (EORTC QLQ-C30). The median length of follow-up was 37 months (range, 13 to 75). The PSSHN scores were 89, 84, and 86, respectively, for eating in public, understandability of speech and normalcy of diet (100 = normal function). Significantly lower scores for understandability of speech were observed in patients with advanced and laryngeal carcinomas. Normalcy of diet was affected negatively by the severity of xerostomia. All mean functional scale scores of the EORTC QLQ-C30 module were 20% to 25% below the higher score. Most of these scale scores were significantly affected by the severity of xerostomia. Patients treated with concomitant boost RT for laryngeal and hypopharyngeal carcinomas appear to have similar QOL and functional outcome to those reported for patients treated with conventional or hyperfractionated RT. As expected, many QOL scales were affected by the severity of xero- stomia.

  1. The sensitivity of patient specific IMRT QC to systematic MLC leaf bank offset errors.

    PubMed

    Rangel, Alejandra; Palte, Gesa; Dunscombe, Peter

    2010-07-01

    Patient specific IMRT QC is performed routinely in many clinics as a safeguard against errors and inaccuracies which may be introduced during the complex planning, data transfer, and delivery phases of this type of treatment. The purpose of this work is to evaluate the feasibility of detecting systematic errors in MLC leaf bank position with patient specific checks. 9 head and neck (H&N) and 14 prostate IMRT beams were delivered using MLC files containing systematic offsets (+/- 1 mm in two banks, +/- 0.5 mm in two banks, and 1 mm in one bank of leaves). The beams were measured using both MAPCHECK (Sun Nuclear Corp., Melbourne, FL) and the aS1000 electronic portal imaging device (Varian Medical Systems, Palo Alto, CA). Comparisons with calculated fields, without offsets, were made using commonly adopted criteria including absolute dose (AD) difference, relative dose difference, distance to agreement (DTA), and the gamma index. The criteria most sensitive to systematic leaf bank offsets were the 3% AD, 3 mm DTA for MAPCHECK and the gamma index with 2% AD and 2 mm DTA for the EPID. The criterion based on the relative dose measurements was the least sensitive to MLC offsets. More highly modulated fields, i.e., H&N, showed greater changes in the percentage of passing points due to systematic MLC inaccuracy than prostate fields. None of the techniques or criteria tested is sufficiently sensitive, with the population of IMRT fields, to detect a systematic MLC offset at a clinically significant level on an individual field. Patient specific QC cannot, therefore, substitute for routine QC of the MLC itself.

  2. IMRT for Sinonasal Tumors Minimizes Severe Late Ocular Toxicity and Preserves Disease Control and Survival

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Duprez, Frederic, E-mail: frederic.duprez@ugent.be; Madani, Indira; Morbee, Lieve

    2012-05-01

    Purpose: To report late ocular (primary endpoint) and other toxicity, disease control, and survival (secondary endpoints) after intensity-modulated radiotherapy (IMRT) for sinonasal tumors. Methods and Materials: Between 1998 and 2009, 130 patients with nonmetastatic sinonasal tumors were treated with IMRT at Ghent University Hospital. Prescription doses were 70 Gy (n = 117) and 60-66 Gy (n = 13) at 2 Gy per fraction over 6-7 weeks. Most patients had adenocarcinoma (n = 82) and squamous cell carcinoma (n = 23). One hundred and one (101) patients were treated postoperatively. Of 17 patients with recurrent tumors, 9 were reirradiated. T-stages weremore » T1-2 (n = 39), T3 (n = 21), T4a (n = 38), and T4b (n = 22). Esthesioneuroblastoma was staged as Kadish A, B, and C in 1, 3, and 6 cases, respectively. Results: Median follow-up was 52, range 15-121 months. There was no radiation-induced blindness in 86 patients available for late toxicity assessment ({>=}6 month follow-up). We observed late Grade 3 tearing in 10 patients, which reduced to Grade 1-2 in 5 patients and Grade 3 visual impairment because of radiation-induced ipsilateral retinopathy and neovascular glaucoma in 1 patient. There was no severe dry eye syndrome. The worst grade of late ocular toxicity was Grade 3 (n = 11), Grade 2 (n = 31), Grade 1 (n = 33), and Grade 0 (n = 11). Brain necrosis and osteoradionecrosis occurred in 6 and 1 patients, respectively. Actuarial 5-year local control and overall survival were 59% and 52%, respectively. On multivariate analysis local control was negatively affected by cribriform plate and brain invasion (p = 0.044 and 0.029, respectively) and absence of surgery (p = 0.009); overall survival was negatively affected by cribriform plate and orbit invasion (p = 0.04 and <0.001, respectively) and absence of surgery (p = 0.001). Conclusions: IMRT for sinonasal tumors allowed delivering high doses to targets at minimized ocular toxicity, while maintaining disease control and

  3. Hybrid adaptive radiotherapy with on-line MRI in cervix cancer IMRT.

    PubMed

    Oh, Seungjong; Stewart, James; Moseley, Joanne; Kelly, Valerie; Lim, Karen; Xie, Jason; Fyles, Anthony; Brock, Kristy K; Lundin, Anna; Rehbinder, Henrik; Milosevic, Michael; Jaffray, David; Cho, Young-Bin

    2014-02-01

    Substantial organ motion and tumor shrinkage occur during radiotherapy for cervix cancer. IMRT planning studies have shown that the quality of radiation delivery is influenced by these anatomical changes, therefore the adaptation of treatment plans may be warranted. Image guidance with off-line replanning, i.e. hybrid-adaptation, is recognized as one of the most practical adaptation strategies. In this study, we investigated the effects of soft tissue image guidance using on-line MR while varying the frequency of off-line replanning on the adaptation of cervix IMRT. 33 cervical cancer patients underwent planning and weekly pelvic MRI scans during radiotherapy. 5 patients of 33 were identified in a previous retrospective adaptive planning study, in which the coverage of gross tumor volume/clinical target volume (GTV/CTV) was not acceptable given single off-line IMRT replan using a 3mm PTV margin with bone matching. These 5 patients and a randomly selected 10 patients from the remaining 28 patients, a total of 15 patients of 33, were considered in this study. Two matching methods for image guidance (bone to bone and soft tissue to dose matrix) and three frequencies of off-line replanning (none, single, and weekly) were simulated and compared with respect to target coverage (cervix, GTV, lower uterus, parametrium, upper vagina, tumor related CTV and elective lymph node CTV) and OAR sparing (bladder, bowel, rectum, and sigmoid). Cost (total process time) and benefit (target coverage) were analyzed for comparison. Hybrid adaptation (image guidance with off-line replanning) significantly enhanced target coverage for both 5 difficult and 10 standard cases. Concerning image guidance, bone matching was short of delivering enough doses for 5 difficult cases even with a weekly off-line replan. Soft tissue image guidance proved successful for all cases except one when single or more frequent replans were utilized in the difficult cases. Cost and benefit analysis preferred

  4. SU-F-T-352: Development of a Knowledge Based Automatic Lung IMRT Planning Algorithm with Non-Coplanar Beams

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zhu, W; Wu, Q; Yuan, L

    Purpose: To improve the robustness of a knowledge based automatic lung IMRT planning method and to further validate the reliability of this algorithm by utilizing for the planning of clinical cases with non-coplanar beams. Methods: A lung IMRT planning method which automatically determines both plan optimization objectives and beam configurations with non-coplanar beams has been reported previously. A beam efficiency index map is constructed to guide beam angle selection in this algorithm. This index takes into account both the dose contributions from individual beams and the combined effect of multiple beams which is represented by a beam separation score. Wemore » studied the effect of this beam separation score on plan quality and determined the optimal weight for this score.14 clinical plans were re-planned with the knowledge-based algorithm. Significant dosimetric metrics for the PTV and OARs in the automatic plans are compared with those in the clinical plans by the two-sample t-test. In addition, a composite dosimetric quality index was defined to obtain the relationship between the plan quality and the beam separation score. Results: On average, we observed more than 15% reduction on conformity index and homogeneity index for PTV and V{sub 40}, V{sub 60} for heart while an 8% and 3% increase on V{sub 5}, V{sub 20} for lungs, respectively. The variation curve of the composite index as a function of angle spread score shows that 0.6 is the best value for the weight of the beam separation score. Conclusion: Optimal value for beam angle spread score in automatic lung IMRT planning is obtained. With this value, model can result in statistically the “best” achievable plans. This method can potentially improve the quality and planning efficiency for IMRT plans with no-coplanar angles.« less

  5. SU-E-T-811: Volumetric Modulated Arc Therapy Vs. C-IMRT for the Treatment of Upper Thoracic Esophageal Cancer

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zhang, W; Wu, L; Lu, J

    2015-06-15

    Purpose: To compare plans using volumetric-modulated arc therapy (VMAT) with conventional sliding window intensity-modulated radiation therapy (c-IMRT) to treat upper thoracic esophageal cancer (EC). Methods: CT datasets of 11 patients with upper thoracic EC were identified. Four plans were generated for each patient: c-IMRT with 5 fields (5F) and VMAT with a single arc (1A), two arcs (2A), or three arcs (3A). The prescribed doses were 64 Gy/32 F for the primary tumor (planning target volume 64, PTV64). The dose-volume histogram data, the number of monitoring units (MUs) and the treatment time (TT) for the different plans were compared. Results:more » All of the plans generated similar dose distributions for PTVs and organs at risk (OARs), except that the 2A- and 3A-VMAT plans yielded a significantly higher conformity index (CI) than the c-IMRT plan. The CI of the PTV64 was improved by increasing the number of arcs in the VMAT plans. The maximum spinal cord dose and the planning risk volume of the spinal cord dose for the two techniques were similar. The 2A- and 3A-VMAT plans yielded lower mean lung doses and heart V50 than the c-IMRT. The V20 and V30 for the lungs in all of the VMAT plans were lower than those in the c-IMRT plan, at the expense of increasing V5, V10 and V13. The VMAT plan resulted in significant reductions in MUs and TT. Conclusion: The 2A-VMAT plan appeared to spare the lungs from moderate-dose irradiation most effectively of all plans, at the expense of increasing the low-dose irradiation volume, and also significantly reduced the number of required MUs and the TT. The CI of the PTVs and the OARs was improved by increasing the arc-number from 1 to 2. however, no significant improvement was observed using the 3A-VMAT, except for an increase in the TT. This work was sponsored by Shantou University Medical College Clinical Research Enhancement Initiative(NO.201424)« less

  6. SU-F-T-336: A Quick Auto-Planning (QAP) Method for Patient Intensity Modulated Radiotherapy (IMRT)

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Peng, J; Zhang, Z; Wang, J

    2016-06-15

    Purpose: The aim of this study is to develop a quick auto-planning system that permits fast patient IMRT planning with conformal dose to the target without manual field alignment and time-consuming dose distribution optimization. Methods: The planning target volume (PTV) of the source and the target patient were projected to the iso-center plane in certain beameye- view directions to derive the 2D projected shapes. Assuming the target interior was isotropic for each beam direction boundary analysis under polar coordinate was performed to map the source shape boundary to the target shape boundary to derive the source-to-target shape mapping function. Themore » derived shape mapping function was used to morph the source beam aperture to the target beam aperture over all segments in each beam direction. The target beam weights were re-calculated to deliver the same dose to the reference point (iso-center) as the source beam did in the source plan. The approach was tested on two rectum patients (one source patient and one target patient). Results: The IMRT planning time by QAP was 5 seconds on a laptop computer. The dose volume histograms and the dose distribution showed the target patient had the similar PTV dose coverage and OAR dose sparing with the source patient. Conclusion: The QAP system can instantly and automatically finish the IMRT planning without dose optimization.« less

  7. Hypofractionated IMRT of the Prostate Bed After Radical Prostatectomy: Acute Toxicity in the PRIAMOS-1 Trial

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Katayama, Sonja, E-mail: sonja.katayama@med.uni-heidelberg.de; Striecker, Thorbjoern; Kessel, Kerstin

    Purpose: Hypofractionated radiation therapy as primary treatment for prostate cancer is currently being investigated in large phase 3 trials. However, there are few data on postoperative hypofractionation. The Radiation therapy for the Prostate Bed With or Without the Pelvic Lymph Nodes (PRIAMOS 1) trial was initiated as a prospective phase 2 trial to assess treatment safety and toxicity of a hypofractionated intensity modulated radiation therapy (IMRT) of the prostate bed. Methods and Materials: From February to September 2012, 40 patients with indications for adjuvant or salvage radiation therapy were enrolled. One patient dropped out before treatment. Patients received 54 Gy inmore » 18 fractions to the prostate bed with IMRT and daily image guidance. Gastrointestinal (GI) and genitourinary (GU) toxicities (according to National Cancer Institute Common Terminology Criteria for Adverse Events, version 4.0) were recorded weekly during treatment and 10 weeks after radiation therapy. Results: Overall acute toxicity was favorable, with no recorded adverse events grade ≥3. Acute GI toxicity rates were 56.4% (grade 1) and 17.9% (grade 2). Acute GU toxicity was recorded in 35.9% of patients (maximum grade 1). Urinary stress incontinence was not influenced by radiation therapy. The incidence of grade 1 urinary urge incontinence increased from 2.6% before to 23.1% 10 weeks after therapy, but grade 2 urge incontinence remained unchanged. Conclusions: Postoperative hypofractionated IMRT of the prostate bed is tolerated well, with no severe acute side effects.« less

  8. Investigation of a pulsed current annealing method in reusing MOSFET dosimeters for in vivo IMRT dosimetry.

    PubMed

    Luo, Guang-Wen; Qi, Zhen-Yu; Deng, Xiao-Wu; Rosenfeld, Anatoly

    2014-05-01

    To explore the feasibility of pulsed current annealing in reusing metal oxide semiconductor field-effect transistor (MOSFET) dosimeters for in vivo intensity modulated radiation therapy (IMRT) dosimetry. Several MOSFETs were irradiated at d(max) using a 6 MV x-ray beam with 5 V on the gate and annealed with zero bias at room temperature. The percentage recovery of threshold voltage shift during multiple irradiation-annealing cycles was evaluated. Key dosimetry characteristics of the annealed MOSFET such as the dosimeter's sensitivity, reproducibility, dose linearity, and linearity of response within the dynamic range were investigated. The initial results of using the annealed MOSFETs for IMRT dosimetry practice were also presented. More than 95% of threshold voltage shift can be recovered after 24-pulse current continuous annealing in 16 min. The mean sensitivity degradation was found to be 1.28%, ranging from 1.17% to 1.52%, during multiple annealing procedures. Other important characteristics of the annealed MOSFET remained nearly consistent before and after annealing. Our results showed there was no statistically significant difference between the annealed MOSFETs and their control samples in absolute dose measurements for IMRT QA (p = 0.99). The MOSFET measurements agreed with the ion chamber results on an average of 0.16% ± 0.64%. Pulsed current annealing provides a practical option for reusing MOSFETs to extend their operational lifetime. The current annealing circuit can be integrated into the reader, making the annealing procedure fully automatic.

  9. Single-arc volumetric-modulated arc therapy (sVMAT) as adjuvant treatment for gastric cancer: Dosimetric comparisons with three-dimensional conformal radiotherapy (3D-CRT) and intensity-modulated radiotherapy (IMRT)

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wang, Xin; Li, Guangjun; Zhang, Yingjie

    2013-01-01

    To compare the dosimetric differences between the single-arc volumetric-modulated arc therapy (sVMAT), 3-dimensional conformal radiotherapy (3D-CRT), and intensity-modulated radiotherapy (IMRT) techniques in treatment planning for gastric cancer as adjuvant radiotherapy. Twelve patients were retrospectively analyzed. In each patient's case, the parameters were compared based on the dose-volume histogram (DVH) of the sVMAT, 3D-CRT, and IMRT plans, respectively. Three techniques showed similar target dose coverage. The maximum and mean doses of the target were significantly higher in the sVMAT plans than that in 3D-CRT plans and in the 3D-CRT/IMRT plans, respectively, but these differences were clinically acceptable. The IMRT and sVMATmore » plans successfully achieved better target dose conformity, reduced the V{sub 20/30}, and mean dose of the left kidney, as well as the V{sub 20/30} of the liver, compared with the 3D-CRT plans. And the sVMAT technique reduced the V{sub 20} of the liver much significantly. Although the maximum dose of the spinal cord were much higher in the IMRT and sVMAT plans, respectively (mean 36.4 vs 39.5 and 40.6 Gy), these data were still under the constraints. Not much difference was found in the analysis of the parameters of the right kidney, intestine, and heart. The IMRT and sVMAT plans achieved similar dose distribution to the target, but superior to the 3D-CRT plans, in adjuvant radiotherapy for gastric cancer. The sVMAT technique improved the dose sparings of the left kidney and liver, compared with the 3D-CRT technique, but showed few dosimetric advantages over the IMRT technique. Studies are warranted to evaluate the clinical benefits of the VMAT treatment for patients with gastric cancer after surgery in the future.« less

  10. Generalized field-splitting algorithms for optimal IMRT delivery efficiency.

    PubMed

    Kamath, Srijit; Sahni, Sartaj; Li, Jonathan; Ranka, Sanjay; Palta, Jatinder

    2007-09-21

    Intensity-modulated radiation therapy (IMRT) uses radiation beams of varying intensities to deliver varying doses of radiation to different areas of the tissue. The use of IMRT has allowed the delivery of higher doses of radiation to the tumor and lower doses to the surrounding healthy tissue. It is not uncommon for head and neck tumors, for example, to have large treatment widths that are not deliverable using a single field. In such cases, the intensity matrix generated by the optimizer needs to be split into two or three matrices, each of which may be delivered using a single field. Existing field-splitting algorithms used the pre-specified arbitrary split line or region where the intensity matrix is split along a column, i.e., all rows of the matrix are split along the same column (with or without the overlapping of split fields, i.e., feathering). If three fields result, then the two splits are along the same two columns for all rows. In this paper we study the problem of splitting a large field into two or three subfields with the field width as the only constraint, allowing for an arbitrary overlap of the split fields, so that the total MU efficiency of delivering the split fields is maximized. Proof of optimality is provided for the proposed algorithm. An average decrease of 18.8% is found in the total MUs when compared to the split generated by a commercial treatment planning system and that of 10% is found in the total MUs when compared to the split generated by our previously published algorithm.

  11. Extraretinal induced visual sensations during IMRT of the brain.

    PubMed

    Wilhelm-Buchstab, Timo; Buchstab, Barbara Myrthe; Leitzen, Christina; Garbe, Stephan; Müdder, Thomas; Oberste-Beulmann, Susanne; Sprinkart, Alois Martin; Simon, Birgit; Nelles, Michael; Block, Wolfgang; Schoroth, Felix; Schild, Hans Heinz; Schüller, Heinrich

    2015-01-01

    We observed visual sensations (VSs) in patients undergoing intensity modulated radiotherapy (IMRT) of the brain without the beam passing through ocular structures. We analyzed this phenomenon especially with regards to reproducibility, and origin. Analyzed were ten consecutive patients (aged 41-71 years) with glioblastoma multiforme who received pulsed IMRT (total dose 60Gy) with helical tomotherapy (TT). A megavolt-CT (MVCT) was performed daily before treatment. VSs were reported and recorded using a triggered event recorder. The frequency of VSs was calculated and VSs were correlated with beam direction and couch position. Subjective patient perception was plotted on an 8x8 visual field (VF) matrix. Distance to the orbital roof (OR) from the first beam causing a VS was calculated from the Dicom radiation therapy data and MVCT data. During 175 treatment sessions (average 17.5 per patient) 5959 VSs were recorded and analyzed. VSs occurred only during the treatment session not during the MVCTs. Plotting events over time revealed patient-specific patterns. The average cranio-caudad extension of VS-inducing area was 63.4mm (range 43.24-92.1mm). The maximum distance between the first VS and the OR was 56.1mm so that direct interaction with the retina is unlikely. Data on subjective visual perception showed that VSs occurred mainly in the upper right and left quadrants of the VF. Within the visual pathways the highest probability for origin of VSs was seen in the optic chiasm and the optic tract (22%). There is clear evidence that interaction of photon irradiation with neuronal structures distant from the eye can lead to VSs.

  12. Clinical implementation and error sensitivity of a 3D quality assurance protocol for prostate and thoracic IMRT

    PubMed Central

    Cotter, Christopher; Turcotte, Julie Catherine; Crawford, Bruce; Sharp, Gregory; Mah'D, Mufeed

    2015-01-01

    This work aims at three goals: first, to define a set of statistical parameters and plan structures for a 3D pretreatment thoracic and prostate intensity‐modulated radiation therapy (IMRT) quality assurance (QA) protocol; secondly, to test if the 3D QA protocol is able to detect certain clinical errors; and third, to compare the 3D QA method with QA performed with single ion chamber and 2D gamma test in detecting those errors. The 3D QA protocol measurements were performed on 13 prostate and 25 thoracic IMRT patients using IBA's COMPASS system. For each treatment planning structure included in the protocol, the following statistical parameters were evaluated: average absolute dose difference (AADD), percent structure volume with absolute dose difference greater than 6% (ADD6), and 3D gamma test. To test the 3D QA protocol error sensitivity, two prostate and two thoracic step‐and‐shoot IMRT patients were investigated. Errors introduced to each of the treatment plans included energy switched from 6 MV to 10 MV, multileaf collimator (MLC) leaf errors, linac jaws errors, monitor unit (MU) errors, MLC and gantry angle errors, and detector shift errors. QA was performed on each plan using a single ion chamber and 2D array of ion chambers for 2D and 3D QA. Based on the measurements performed, we established a uniform set of tolerance levels to determine if QA passes for each IMRT treatment plan structure: maximum allowed AADD is 6%; maximum 4% of any structure volume can be with ADD6 greater than 6%, and maximum 4% of any structure volume may fail 3D gamma test with test parameters 3%/3 mm DTA. Out of the three QA methods tested the single ion chamber performed the worst by detecting 4 out of 18 introduced errors, 2D QA detected 11 out of 18 errors, and 3D QA detected 14 out of 18 errors. PACS number: 87.56.Fc PMID:26699299

  13. SU-E-T-541: Bolus Effect of Thermoplastic Masks in IMRT and VMAT Head and Neck Treatments

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zhen, H; Nedzi, L; Chen, S

    2014-06-01

    Purpose: To quantitatively evaluate the bolus effect of thermoplalstic mask on patient skin dose during multi-field IMRT and VMAT treatment. Methods: The clinically approved target contours for five head and neck patients were deformably registered to an anthropomorphic Rando phantom. Two plans: Multifield IMRT plan with 7-9 beams and VMAT plan with 2-4 arcs were created for each patient following same dose constraints. 3mm skin was excluded from PTVs but not constrained during optimization. The prescription dose was 200-220 cGy/fraction. A thermoplastic head and shoulder mask was customized for the Rando phantom. Each plan was delivered to the phantom twicemore » with and without mask. During each delivery, two rectangular strips of EBT3 films (1cm x 6.8cm) were placed across the anterior upper and lower neck near PTVs to measure the surface dose. For consistency films were positioned at same locations for same patient. A total of 8 film strips were obtained for each patient. Film dose was calibrated in the range of 0-400cGy on the day of plan delivery. For dose comparison 3 regions of interests (ROIs) of 1×1 cm{sup 2} were selected at left, right and middle part of each film, resulting in 6 point doses at each plan delivery. Results: The films without mask show relatively uniform dose distribution while those with mask clearly show mesh pattern of mask, usually indicating an increase in skin dose. On average the increase in skin dose over all ROIs with mask was 31.9%(±14.8%) with a range of 11.4%- 58.4%. There is no statistically significant difference (p=0.44) between skin dose increase in VMAT (30.8%±15.3%) and IMRT delivery (33.0%±14.9%). Conclusion: Thermoplastic immobilization masks increase surface dose for HN patient by around 30%. The magnitude is comparable between multi-field IMRT and VMAT. Radiochromic EBT3 film serves as an effective tool to quantify bolus effect.« less

  14. SU-E-T-593: Clinical Evaluation of Direct Aperture Optimization in Head/Neck and Prostate IMRT Treatment

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hosini, M; GALAL, M; Emam, I

    2014-06-01

    Purpose: To investigate the planning and dosimetric advantages of direct aperture optimization (DAO) over beam-let optimization in IMRT treatment of head and neck (H/N) and prostate cancers. Methods: Five Head and Neck as well as five prostate patients were planned using the beamlet optimizer in Elekta-Xio ver 4.6 IMRT treatment planning system. Based on our experience in beamlet IMRT optimization, PTVs in H/N plans were prescribed to 70 Gy delivered by 7 fields. While prostate PTVs were prescribed to 76 Gy with 9 fields. In all plans, fields were set to be equally spaced. All cases were re-planed using Directmore » Aperture optimizer in Prowess Panther ver 5.01 IMRT planning system at same configurations and dose constraints. Plans were evaluated according to ICRU criteria, number of segments, number of monitor units and planning time. Results: For H/N plans, the near maximum dose (D2) and the dose that covers 95% D95 of PTV has improved by 4% in DAO. For organs at risk (OAR), DAO reduced the volume covered by 30% (V30) in spinal cord, right parotid, and left parotid by 60%, 54%, and 53% respectively. This considerable dosimetric quality improvement achieved using 25% less planning time and lower number of segments and monitor units by 46% and 51% respectively. In DAO prostate plans, Both D2 and D95 for the PTV were improved by only 2%. The V30 of the right femur, left femur and bladder were improved by 35%, 15% and 3% respectively. On the contrary, the rectum V30 got even worse by 9%. However, number of monitor units, and number of segments decreased by 20% and 25% respectively. Moreover the planning time reduced significantly too. Conclusion: DAO introduces considerable advantages over the beamlet optimization in regards to organs at risk sparing. However, no significant improvement occurred in most studied PTVs.« less

  15. Clinical applications of image guided-intensity modulated radiation therapy (IG-IMRT) for conformal avoidance of normal tissue

    NASA Astrophysics Data System (ADS)

    Gutierrez, Alonso Navar

    2007-12-01

    Recent improvements in imaging technology and radiation delivery have led to the development of advanced treatment techniques in radiotherapy which have opened the door for novel therapeutic approaches to improve the efficacy of radiation cancer treatments. Among these advances is image-guided, intensity modulated radiation therapy (IG-IMRT), in which imaging is incorporated to aid in inter-/intra-fractional target localization and to ensure accurate delivery of precise and highly conformal dose distributions. In principle, clinical implementation of IG-IMRT should improve normal tissue sparing and permit effective biological dose escalation thus widening the radiation therapeutic window and lead to increases in survival through improved local control of primary neoplastic diseases. Details of the development of three clinical applications made possible solely with IG-IMRT radiation delivery techniques are presented: (1) Laparoscopically implanted tissue expander radiotherapy (LITE-RT) has been developed to enhance conformal avoidance of normal tissue during the treatment of intra-abdominopelvic cancers. LITE-RT functions by geometrically displacing surrounding normal tissue and isolating the target volume through the interfractional inflation of a custom-shaped tissue expander throughout the course of treatment. (2) The unique delivery geometry of helical tomotherapy, a novel form of IG-IMRT, enables the delivery of composite treatment plan m which whole brain radiotherapy (WBRT) with hippocampal avoidance, hypothesized to reduce the risk of memory function decline and improve the patient's quality of life, and simultaneously integrated boost to multiple brain metastases to improve intracranial tumor control is achieved. (3) Escalation of biological dose to targets through integrated, selective subvolume boosts have been shown to efficiently increase tumor dose without significantly increasing normal tissue dose. Helical tomotherapy was used to investigate the

  16. Reduced Toxicity With Intensity Modulated Radiation Therapy (IMRT) for Desmoplastic Small Round Cell Tumor (DSRCT): An Update on the Whole Abdominopelvic Radiation Therapy (WAP-RT) Experience

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Desai, Neil B.; Stein, Nicholas F.; LaQuaglia, Michael P.

    2013-01-01

    Purpose: Desmoplastic small round cell tumor (DSRCT) is a rare malignancy typically involving the peritoneum in young men. Whole abdominopelvic radiation therapy (WAP-RT) using conventional 2-dimensional (2D) radiation therapy (RT) is used to address local recurrence but has been limited by toxicity. Our objectives were to assess the benefit of intensity modulated radiation therapy (IMRT) on toxicity and to update the largest series on radiation for DSRCT. Methods and Materials: The records of 31 patients with DSRCT treated with WAP-RT (22 with 2D-RT and 9 with IMRT) between 1992 and 2011 were retrospectively reviewed. All received multi-agent chemotherapy and maximalmore » surgical debulking followed by 30 Gy of WAP-RT. A further focal boost of 12 to 24 Gy was used in 12 cases. Boost RT and autologous stem cell transplantation were nearly exclusive to patients treated with 2D-RT. Toxicities were assessed with the Common Terminology Criteria for Adverse Events. Dosimetric analysis compared IMRT and simulated 2D-RT dose distributions. Results: Of 31 patients, 30 completed WAP-RT, with a median follow-up after RT of 19 months. Acute toxicity was reduced with IMRT versus 2D-RT: P=.04 for gastrointestinal toxicity of grade 2 or higher (33% vs 77%); P=.02 for grade 4 hematologic toxicity (33% vs 86%); P=.01 for rates of granulocyte colony-stimulating factor; and P=.04 for rates of platelet transfusion. Post treatment red blood cell and platelet transfusion rates were also reduced (P=.01). IMRT improved target homogeneity ([D05-D95]/D05 of 21% vs 46%) and resulted in a 21% mean bone dose reduction. Small bowel obstruction was the most common late toxicity (23% overall). Updated 3-year overall survival and progression-free survival rates were 50% and 24%, respectively. Overall survival was associated with distant metastasis at diagnosis on multivariate analysis. Most failures remained intraperitoneal (88%). Conclusions: IMRT for consolidative WAP-RT in DSRCT improves

  17. An EGSnrc Monte Carlo study of the microionization chamber for reference dosimetry of narrow irregular IMRT beamlets.

    PubMed

    Capote, Roberto; Sánchez-Doblado, Francisco; Leal, Antonio; Lagares, Juan Ignacio; Arráns, Rafael; Hartmann, Günther H

    2004-09-01

    Intensity modulated radiation therapy (IMRT) has evolved toward the use of many small radiation fields, or "beamlets," to increase the resolution of the intensity map. The size of smaller beamlets can be typically about 1-5 cm2. Therefore small ionization chambers (IC) with sensitive volumes < or = 0.1 cm3 are generally used for dose verification of IMRT treatment. The dosimetry of these narrow photon beams pertains to the so-called nonreference conditions for beam calibration. The use of ion chambers for such narrow beams remains questionable due to the lack of electron equilibrium in most of the field. The present contribution aims to estimate, by the Monte Carlo (MC) method, the total correction needed to convert the IBA-Wellhöfer NAC007 micro IC measured charge in such radiation field to the absolute dose to water. Detailed geometrical simulation of the microionization chamber was performed. The ion chamber was always positioned at a 10 cm depth in water, parallel to the beam axis. The delivered doses to air and water cavity were calculated using the CAVRZ EGSnrc user code. The 6 MV phase-spaces for Primus Clinac (Siemens) used as an input to the CAVRZnrc code were derived by BEAM/EGS4 modeling of the treatment head of the machine along with the multileaf collimator [Sánchez-Doblado et al., Phys. Med. Biol. 48, 2081-2099 (2003)] and contrasted with experimental measurements. Dose calculations were carried out for two irradiation geometries, namely, the reference 10x10 cm2 field and an irregular (approximately 2x2 cm2) IMRT beamlet. The dose measured by the ion chamber is estimated by MC simulation as a dose averaged over the air cavity inside the ion-chamber (Dair). The absorbed dose to water is derived as the dose deposited inside the same volume, in the same geometrical position, filled and surrounded by water (Dwater) in the absence of the ionization chamber. Therefore, the Dwater/Dair dose ratio is a MC direct estimation of the total correction factor

  18. SU-E-J-193: Feasibility of MRI-Only Based IMRT Planning for Pancreatic Cancer

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Prior, P; Botros, M; Chen, X

    2014-06-01

    Purpose: With the increasing use of MRI simulation and the advent of MRI-guided delivery, it is desirable to use MRI only for treatment planning. In this study, we assess the dosimetric difference between MRI- and CTbased IMRT planning for pancreatic cancer. Methods: Planning CTs and MRIs acquired for a representative pancreatic cancer patient were used. MRI-based planning utilized forced relative electron density (rED) assignment of organ specific values from IRCU report 46, where rED = 1.029 for PTV and a rED = 1.036 for non-specified tissue (NST). Six IMRT plans were generated with clinical dose-volume (DV) constraints using a researchmore » Monaco planning system employing Monte Carlo dose calculation with optional perpendicular magnetic field (MF) of 1.5T. The following five plans were generated and compared with the planning CT: 1.) CT plan with MF and dose recalculation without optimization; 2.) MRI (T2) plan with target and OARs redrawn based on MRI, forced rED, no MF, and recalculation without optimization; 3.) Similar as in 2 but with MF; 4.) MRI plan with MF but without optimization; and 5.) Similar as in 4 but with optimization. Results: Generally, noticeable differences in PTV point doses and DV parameters (DVPs) between the CT-and MRI-based plans with and without the MF were observed. These differences between the optimized plans were generally small, mostly within 2%. Larger differences were observed in point doses and mean doses for certain OARs between the CT and MRI plan, mostly due to differences between image acquisition times. Conclusion: MRI only based IMRT planning for pancreatic cancer is feasible. The differences observed between the optimized CT and MRI plans with or without the MF were practically negligible if excluding the differences between MRI and CT defined structures.« less

  19. Clinical radiobiology of stage T2-T3 bladder cancer.

    PubMed

    Majewski, Wojciech; Maciejewski, Boguslaw; Majewski, Stanislaw; Suwinski, Rafal; Miszczyk, Leszek; Tarnawski, Rafal

    2004-09-01

    To evaluate the relationship between total radiation dose and overall treatment time (OTT) with the treatment outcome, with adjustment for selected clinical factors, in patients with Stage T2-T3 bladder cancer treated with curative radiotherapy (RT). The analysis was based on 480 patients with Stage T2-T3 bladder cancer who were treated at the Center of Oncology in Gliwice between 1975 and 1995. The mean total radiation dose was 65.5 Gy, and the mean OTT was 51 days. In 261 patients (54%), planned and unplanned gaps occurred during RT. Four fractionation schedules were used: (1) conventional fractionation (once daily, 1.8-2.5 Gy/fraction); (2) protracted fractionation (pelvic RT, once daily, 1.6-1.7 Gy/fraction, boost RT, once daily, 2.0 Gy/fraction); (3) accelerated hyperfractionated boost (pelvic RT, once daily, 2.0 Gy/fraction; boost RT, twice daily, 1.3-1.4 Gy/fraction); and (4) accelerated hyperfractionation (pelvic and boost RT, twice daily, 1.2-1.5 Gy/fraction). In all fractionation schedules, the total radiation dose was similar (average 65.5 Gy), but the OTT was different (mean 53 days for conventional fractionation, 62 days for protracted fractionation, 45 days for accelerated hyperfractionated boost, and 41 days for accelerated hyperfractionation). A Cox proportional hazard model and maximum likelihood logistic model were used to evaluate the relationship between the treatment-related parameters (total radiation dose, dose per fraction, and OTT) and clinical factors (clinical T stage, hemoglobin level and bladder capacity before RT) and treatment outcome. With a median follow-up of 76 months, the actuarial 5-year local control rate was 47%, and the overall survival rate was 40%. The logistic analysis, which included the total dose, OTT, and T stage, revealed that all of these factors were significantly related to tumor control probability (p = 0.021 for total radiation dose, p = 0.038 for OTT, and p = 0.00068 for T stage). A multivariate Cox model, which

  20. Dosimetric characterization and use of GAFCHROMIC EBT3 film for IMRT dose verification

    PubMed Central

    Borca, Valeria Casanova; Russo, Giuliana; Grosso, Pierangelo; Cante, Domenico; Sciacero, Piera; Girelli, Giuseppe; Porta, Maria Rosa La; Tofani, Santi

    2013-01-01

    Radiochromic film has become an important tool to verify dose distributions in highly conformal radiation therapy such as IMRT. Recently, a new generation of these films, EBT3, has become available. EBT3 has the same composition and thickness of the sensitive layer of the previous EBT2 films, but its symmetric layer configuration allows the user to eliminate side orientation dependence, which is reported for EBT2 films. The most important EBT3 characteristics have been investigated, such as response at high‐dose levels, sensitivity to scanner orientation and postirradiation coloration, energy and dose rate dependence, and orientation dependence with respect to film side. Additionally, different IMRT fields were measured with both EBT3 and EBT2 films and evaluated using gamma index analysis. The results obtained show that most of the characteristics of EBT3 film are similar to the EBT2 film, but the orientation dependence with respect to film side is completely eliminated in EBT3 films. The study confirms that EBT3 film can be used for clinical practice in the same way as the previous EBT2 film. PACS number: 87.56.Fc PMID:23470940

  1. Outcomes of xerostomia-related quality of life for nasopharyngeal carcinoma treated by IMRT: based on the EORTC QLQ-C30 and H&N35 questionnaires.

    PubMed

    Bian, Xiuhua; Song, Tao; Wu, Shixiu

    2015-01-01

    The aim of this study was to review the published literature addressing the question of whether intensity-modulated radiotherapy (IMRT) resulted in an improvement of quality of life (QoL), especially xerostomia-related QoL of all nasopharyngeal carcinoma patients as time progressed. A literature search of PubMed, Embase and Google Scholar was performed, only reports containing original data of the QoL scores after treated by IMRT were included. Two independent reviewers extracted information of study design, study population, interventions, outcome measures and conclusions for each article. The inclusion criteria were met by 14 articles covering outcomes based on the questionnaires treated by IMRT. Data from same questionnaires (European Organization of Research and Treatment of Cancer QLQ-C30 and H&N35 questionnaires) were exacted and we analyzed four items (global health status, dry mouth and sticky saliva, swallowing, social eating and social contact), which have a close relationship with xerostomia-related QoL. Results indicated that a maximal deterioration of most QoL scales including global health status developed during treatment or at the end of the treatment course and then followed by a gradual recovery to 1 year, 1-2 years after IMRT, compared with their baseline level, some specific head and neck items, most in the EORTC QLQ H&N35, remained worse for the surviving patients. In conclusion, the published data reasonably support the benefits of IMRT in improving QoL, but xerostomia-related items still had a significantly negative effect in 2 years to impact a survivor's QoL.

  2. SU-E-T-605: Performance Evaluation of MLC Leaf-Sequencing Algorithms in Head-And-Neck IMRT

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Jing, J; Lin, H; Chow, J

    2015-06-15

    Purpose: To investigate the efficiency of three multileaf collimator (MLC) leaf-sequencing algorithms proposed by Galvin et al, Chen et al and Siochi et al using external beam treatment plans for head-and-neck intensity modulated radiation therapy (IMRT). Methods: IMRT plans for head-and-neck were created using the CORVUS treatment planning system. The plans were optimized and the fluence maps for all photon beams determined. Three different MLC leaf-sequencing algorithms based on Galvin et al, Chen et al and Siochi et al were used to calculate the final photon segmental fields and their monitor units in delivery. For comparison purpose, the maximum intensitymore » of fluence map was kept constant in different plans. The number of beam segments and total number of monitor units were calculated for the three algorithms. Results: From results of number of beam segments and total number of monitor units, we found that algorithm of Galvin et al had the largest number of monitor unit which was about 70% larger than the other two algorithms. Moreover, both algorithms of Galvin et al and Siochi et al have relatively lower number of beam segment compared to Chen et al. Although values of number of beam segment and total number of monitor unit calculated by different algorithms varied with the head-and-neck plans, it can be seen that algorithms of Galvin et al and Siochi et al performed well with a lower number of beam segment, though algorithm of Galvin et al had a larger total number of monitor units than Siochi et al. Conclusion: Although performance of the leaf-sequencing algorithm varied with different IMRT plans having different fluence maps, an evaluation is possible based on the calculated number of beam segment and monitor unit. In this study, algorithm by Siochi et al was found to be more efficient in the head-and-neck IMRT. The Project Sponsored by the Fundamental Research Funds for the Central Universities (J2014HGXJ0094) and the Scientific Research Foundation

  3. Etoposide and cisplatin versus irinotecan and cisplatin in patients with limited-stage small-cell lung cancer treated with etoposide and cisplatin plus concurrent accelerated hyperfractionated thoracic radiotherapy (JCOG0202): a randomised phase 3 study.

    PubMed

    Kubota, Kaoru; Hida, Toyoaki; Ishikura, Satoshi; Mizusawa, Junki; Nishio, Makoto; Kawahara, Masaaki; Yokoyama, Akira; Imamura, Fumio; Takeda, Koji; Negoro, Shunichi; Harada, Masao; Okamoto, Hiroaki; Yamamoto, Nobuyuki; Shinkai, Tetsu; Sakai, Hiroshi; Matsui, Kaoru; Nakagawa, Kazuhiko; Shibata, Taro; Saijo, Nagahiro; Tamura, Tomohide

    2014-01-01

    Four cycles of etoposide plus cisplatin and accelerated hyperfractionated thoracic radiotherapy (AHTRT) is the standard of care for limited-stage small-cell lung cancer (SCLC). Irinotecan plus cisplatin significantly improved overall survival compared with etoposide plus cisplatin for extensive-stage SCLC. We compared these regimens for overall survival of patients with limited-stage SCLC. We did this phase 3 study in 36 institutions in Japan. Eligibility criteria included age 20-70 years, Eastern Cooperative Oncology Group (ECOG) performance status of 0-1, and adequate organ functions. Eligible patients with previously untreated limited-stage SCLC received one cycle of etoposide plus cisplatin (intravenous etoposide 100 mg/m(2) on days 1-3; intravenous cisplatin 80 mg/m(2) on day 1) plus AHTRT (1.5 Gy twice daily, 5 days a week, total 45 Gy over 3 weeks). Patients without progressive disease following induction therapy were randomised (1:1 ratio, using a minimisation method with biased-coin assignment balancing on ECOG performance status [0 vs 1], response to induction chemoradiotherapy [complete response plus near complete response vs partial response and stable disease], and institution) to receive either three further cycles of consolidation etoposide plus cisplatin or irinotecan plus cisplatin (intravenous irinotecan 60 mg/m(2) on days 1, 8, 15; intravenous cisplatin 60 mg/m(2) on day 1). Patients, physicians, and investigators were aware of allocation. The primary endpoint was overall survival after randomisation; primary analysis was by intention to treat. This trial is registered with ClinicalTrials.gov, number NCT00144989, and the UMIN Clinical Trials Registry, number C000000095. 281 patients were enrolled between Sept 1, 2002, and Oct 2, 2006. After induction etoposide plus cisplatin and AHTRT, 258 patients were randomised to consolidation etoposide plus cisplatin (n=129) or irinotecan plus cisplatin (n=129). In the etoposide plus cisplatin group, median

  4. Performance analysis of a film dosimetric quality assurance procedure for IMRT with regard to the employment of quantitative evaluation methods.

    PubMed

    Winkler, Peter; Zurl, Brigitte; Guss, Helmuth; Kindl, Peter; Stuecklschweiger, Georg

    2005-02-21

    A system for dosimetric verification of intensity-modulated radiotherapy (IMRT) treatment plans using absolute calibrated radiographic films is presented. At our institution this verification procedure is performed for all IMRT treatment plans prior to patient irradiation. Therefore clinical treatment plans are transferred to a phantom and recalculated. Composite treatment plans are irradiated to a single film. Film density to absolute dose conversion is performed automatically based on a single calibration film. A software application encompassing film calibration, 2D registration of measurement and calculated distributions, image fusion, and a number of visual and quantitative evaluation utilities was developed. The main topic of this paper is a performance analysis for this quality assurance procedure, with regard to the specification of tolerance levels for quantitative evaluations. Spatial and dosimetric precision and accuracy were determined for the entire procedure, comprising all possible sources of error. The overall dosimetric and spatial measurement uncertainties obtained thereby were 1.9% and 0.8 mm respectively. Based on these results, we specified 5% dose difference and 3 mm distance-to-agreement as our tolerance levels for patient-specific quality assurance for IMRT treatments.

  5. Validation of OSLD and a treatment planning system for surface dose determination in IMRT treatments

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zhuang, Audrey H., E-mail: hzhuang@usc.edu; Olch, Arthur J.

    2014-08-15

    Purpose: To evaluate the accuracy of skin dose determination for composite multibeam 3D conformal radiation therapy (3DCRT) and intensity modulated radiation therapy (IMRT) treatments using optically stimulated luminescent dosimeters (OSLDs) and Eclipse treatment planning system. Methods: Surface doses measured by OSLDs in the buildup region for open field 6 MV beams, either perpendicular or oblique to the surface, were evaluated by comparing against dose measured by Markus Parallel Plate (PP) chamber, surface diodes, and calculated by Monte Carlo simulations. The accuracy of percent depth dose (PDD) calculation in the buildup region from the authors’ Eclipse system (Version 10), which wasmore » precisely commissioned in the buildup region and was used with 1 mm calculation grid, was also evaluated by comparing to PP chamber measurements and Monte Carlo simulations. Finally, an anthropomorphic pelvic phantom was CT scanned with OSLDs in place at three locations. A planning target volume (PTV) was defined that extended close to the surface. Both an 8 beam 3DCRT and IMRT plan were generated in Eclipse. OSLDs were placed at the CT scanned reference locations to measure the skin doses and were compared to diode measurements and Eclipse calculations. Efforts were made to ensure that the dose comparison was done at the effective measurement points of each detector and corresponding locations in CT images. Results: The depth of the effective measurement point is 0.8 mm for OSLD when used in the buildup region in a 6 MV beam and is 0.7 mm for the authors’ surface diode. OSLDs and Eclipse system both agree well with Monte Carlo and/or Markus PP ion chamber and/or diode in buildup regions in 6 MV beams with normal or oblique incidence and across different field sizes. For the multiple beam 3DCRT plan and IMRT plans, the differences between OSLDs and Eclipse calculations on the surface of the anthropomorphic phantom were within 3% and distance-to-agreement less than 0

  6. Multibeam inverse intensity-modulated radiotherapy (IMRT) for whole breast irradiation: a single center experience in China.

    PubMed

    Yang, Zhaozhi; Zhang, Li; Chen, Xingxing; Ma, Jinli; Mei, Xin; Chen, Jiayi; Yu, Xiaoli; Guo, Xiaomao

    2015-10-27

    To present the clinical experience in our cancer center with multibeam inverse intensity-modulated radiotherapy (IMRT) for early stage breast cancer (BC) patients with whole breast irradiation (WBI). We retrospectively analyzed 622 patients with Stage 0 to III BC treated from 2008 to 2011 with wide local excision and WBI, using an inverse IMRT technique. All of the patients were prescribed a total dose of 50 Gy to the whole breast in 2-Gy fractions, followed by a tumor bed boost of 10 Gy in 5 fractions using an electron beam. Of all of the patients, 132 (21.2%) received whole breast plus regional lymph node (RLN) irradiation. 438 of 622 patients had records of acute skin toxicity based on common terminology criteria (CTC) for adverse events. Two hundred eighty (64%) patients had Grade 0/1 toxicity, 153 (35%) had Grade 2 and only 4 patients experienced grade 3 toxicity. Seventy patients (16%) had moist desquamation. Univariate analysis revealed that breast planning target volume was the only predictive factor for Grade ≥2 acute dermatitis (P = 0.002). After 4 years, 170 patients reported cosmetic results by self-assessment, of whom 151 (89%) patients reported good/excellent cosmetic results, and 17 (11%) patients reported fair assessments. For invasive cancer, the four-year rate of freedom from locoregional recurrence survival was 98.3%. Regarding carcinoma in situ, no patients experienced recurrence. BC patients who underwent conservative surgery followed by inverse IMRT plan exhibited acceptable acute toxicities and clinical outcomes. Longer follow-up is needed.

  7. Investigating multi-objective fluence and beam orientation IMRT optimization

    NASA Astrophysics Data System (ADS)

    Potrebko, Peter S.; Fiege, Jason; Biagioli, Matthew; Poleszczuk, Jan

    2017-07-01

    Radiation Oncology treatment planning requires compromises to be made between clinical objectives that are invariably in conflict. It would be beneficial to have a ‘bird’s-eye-view’ perspective of the full spectrum of treatment plans that represent the possible trade-offs between delivering the intended dose to the planning target volume (PTV) while optimally sparing the organs-at-risk (OARs). In this work, the authors demonstrate Pareto-aware radiotherapy evolutionary treatment optimization (PARETO), a multi-objective tool featuring such bird’s-eye-view functionality, which optimizes fluence patterns and beam angles for intensity-modulated radiation therapy (IMRT) treatment planning. The problem of IMRT treatment plan optimization is managed as a combined monolithic problem, where all beam fluence and angle parameters are treated equally during the optimization. To achieve this, PARETO is built around a powerful multi-objective evolutionary algorithm, called Ferret, which simultaneously optimizes multiple fitness functions that encode the attributes of the desired dose distribution for the PTV and OARs. The graphical interfaces within PARETO provide useful information such as: the convergence behavior during optimization, trade-off plots between the competing objectives, and a graphical representation of the optimal solution database allowing for the rapid exploration of treatment plan quality through the evaluation of dose-volume histograms and isodose distributions. PARETO was evaluated for two relatively complex clinical cases, a paranasal sinus and a pancreas case. The end result of each PARETO run was a database of optimal (non-dominated) treatment plans that demonstrated trade-offs between the OAR and PTV fitness functions, which were all equally good in the Pareto-optimal sense (where no one objective can be improved without worsening at least one other). Ferret was able to produce high quality solutions even though a large number of parameters

  8. Knowledge-based IMRT treatment planning for prostate cancer.

    PubMed

    Chanyavanich, Vorakarn; Das, Shiva K; Lee, William R; Lo, Joseph Y

    2011-05-01

    To demonstrate the feasibility of using a knowledge base of prior treatment plans to generate new prostate intensity modulated radiation therapy (IMRT) plans. Each new case would be matched against others in the knowledge base. Once the best match is identified, that clinically approved plan is used to generate the new plan. A database of 100 prostate IMRT treatment plans was assembled into an information-theoretic system. An algorithm based on mutual information was implemented to identify similar patient cases by matching 2D beam's eye view projections of contours. Ten randomly selected query cases were each matched with the most similar case from the database of prior clinically approved plans. Treatment parameters from the matched case were used to develop new treatment plans. A comparison of the differences in the dose-volume histograms between the new and the original treatment plans were analyzed. On average, the new knowledge-based plan is capable of achieving very comparable planning target volume coverage as the original plan, to within 2% as evaluated for D98, D95, and D1. Similarly, the dose to the rectum and dose to the bladder are also comparable to the original plan. For the rectum, the mean and standard deviation of the dose percentage differences for D20, D30, and D50 are 1.8% +/- 8.5%, -2.5% +/- 13.9%, and -13.9% +/- 23.6%, respectively. For the bladder, the mean and standard deviation of the dose percentage differences for D20, D30, and D50 are -5.9% +/- 10.8%, -12.2% +/- 14.6%, and -24.9% +/- 21.2%, respectively. A negative percentage difference indicates that the new plan has greater dose sparing as compared to the original plan. The authors demonstrate a knowledge-based approach of using prior clinically approved treatment plans to generate clinically acceptable treatment plans of high quality. This semiautomated approach has the potential to improve the efficiency of the treatment planning process while ensuring that high quality plans are

  9. Comparison and Limitations of DVH-Based NTCP Models Derived From 3D-CRT and IMRT Data for Prediction of Gastrointestinal Toxicities in Prostate Cancer Patients by Using Propensity Score Matched Pair Analysis

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Troeller, Almut; Department of Radiotherapy and Radiation Oncology, Ludwig-Maximilians-Universität, Munich; Yan, Di, E-mail: dyan@beaumont.edu

    2015-02-01

    Purpose: This study compared normal tissue complication probability (NTCP) modeling of chronic gastrointestinal toxicities following prostate cancer treatment for 2 treatment modalities. Possible factors causing discrepancies in optimal NTCP model parameters between 3-dimensional conformal radiation therapy (3D-CRT) and intensity modulated RT (IMRT) were analyzed and discussed, including the impact of patient characteristics, image guidance, toxicity scoring bias, and NTCP model limitations. Methods and Materials: Rectal wall dose-volume histograms of 1115 patients treated for prostate cancer under an adaptive radiation therapy protocol were used to model gastrointestinal toxicity grade ≥2 (according to Common Terminology Criteria for Adverse Events). A total ofmore » 457 patients were treated with 3D-CRT and 658 with IMRT. 3D-CRT patients were matched to IMRT patients based on various patient characteristics, using a propensity score–based algorithm. Parameters of the Lyman equivalent uniform dose and cut-off dose logistic regression NTCP models were estimated for the 2 matched treatment modalities and the combined group. Results: After they were matched, the 3D-CRT and IMRT groups contained 275 and 550 patients with a large discrepancy of 28.7% versus 7.8% toxicities, respectively (P<.001). For both NTCP models, optimal parameters found for the 3D-CRT groups did not fit the IMRT patients well and vice versa. Models developed for the combined data overestimated NTCP for the IMRT patients and underestimated NTCP for the 3D-CRT group. Conclusions: Our analysis did not reveal a single definitive cause for discrepancies of model parameters between 3D-CRT and IMRT. Patient characteristics and bias in toxicity scoring, as well as image guidance alone, are unlikely causes of the large discrepancy of toxicities. Whether the cause was inherent to the specific NTCP models used in this study needs to be verified by future investigations. Because IMRT is increasingly

  10. Comparison and limitations of DVH-based NTCP models derived from 3D-CRT and IMRT data for prediction of gastrointestinal toxicities in prostate cancer patients by using propensity score matched pair analysis.

    PubMed

    Troeller, Almut; Yan, Di; Marina, Ovidiu; Schulze, Derek; Alber, Markus; Parodi, Katia; Belka, Claus; Söhn, Matthias

    2015-02-01

    This study compared normal tissue complication probability (NTCP) modeling of chronic gastrointestinal toxicities following prostate cancer treatment for 2 treatment modalities. Possible factors causing discrepancies in optimal NTCP model parameters between 3-dimensional conformal radiation therapy (3D-CRT) and intensity modulated RT (IMRT) were analyzed and discussed, including the impact of patient characteristics, image guidance, toxicity scoring bias, and NTCP model limitations. Rectal wall dose-volume histograms of 1115 patients treated for prostate cancer under an adaptive radiation therapy protocol were used to model gastrointestinal toxicity grade ≥2 (according to Common Terminology Criteria for Adverse Events). A total of 457 patients were treated with 3D-CRT and 658 with IMRT. 3D-CRT patients were matched to IMRT patients based on various patient characteristics, using a propensity score-based algorithm. Parameters of the Lyman equivalent uniform dose and cut-off dose logistic regression NTCP models were estimated for the 2 matched treatment modalities and the combined group. After they were matched, the 3D-CRT and IMRT groups contained 275 and 550 patients with a large discrepancy of 28.7% versus 7.8% toxicities, respectively (P<.001). For both NTCP models, optimal parameters found for the 3D-CRT groups did not fit the IMRT patients well and vice versa. Models developed for the combined data overestimated NTCP for the IMRT patients and underestimated NTCP for the 3D-CRT group. Our analysis did not reveal a single definitive cause for discrepancies of model parameters between 3D-CRT and IMRT. Patient characteristics and bias in toxicity scoring, as well as image guidance alone, are unlikely causes of the large discrepancy of toxicities. Whether the cause was inherent to the specific NTCP models used in this study needs to be verified by future investigations. Because IMRT is increasingly used clinically, it is important that appropriate NTCP model

  11. Risk of Carotid Blowout After Reirradiation of the Head and Neck: A Systematic Review

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    McDonald, Mark W., E-mail: mwmcdona@iupui.edu; Indiana University Health Proton Therapy Center, Bloomington, IN; Moore, Michael G.

    2012-03-01

    Purpose: Carotid blowout (CB) is a rare but frequently fatal complication of head-and-neck (H and N) cancer or its treatment. We sought to determine the reported rate of CB in patients receiving salvage reirradiation for H and N cancer. Methods and Materials: A literature search identified 27 published articles on H and N reirradiation involving 1554 patients, and a pooled analysis was performed to determine the rate of CB. Treatment parameters, including prior radiation dose, interval from prior radiation, dose and fractionation of reirradiation, use of salvage surgery, and chemotherapy, were abstracted and summarized. The cumulative risk of CB wasmore » compared between groups using Fisher's exact test. Results: Among 1554 patients receiving salvage H and N reirradiation, there were 41 reported CBs, for a rate of 2.6%; 76% were fatal. In patients treated in a continuous course with 1.8-2-Gy daily fractions or 1.2-Gy twice-daily fractions, 36% of whom received concurrent chemotherapy, the rate of CB was 1.3%, compared with 4.5% in patients treated with 1.5 Gy twice daily in alternating weeks or with delayed accelerated hyperfractionation, all of whom received concurrent chemotherapy (p = 0.002). There was no statistically significant difference in the rate of CB between patients treated with or without concurrent chemotherapy, or between patients treated with or without salvage surgery before reirradiation. Conclusion: Carotid blowout is an infrequent but serious complication of salvage reirradiation for H and N cancer. The rate of CB was lower among patients treated with conventional or hyperfractionated schedules compared with regimens of accelerated hyperfractionation, though heterogeneous patient populations and treatment parameters preclude definite conclusions. Given the high mortality rate of CB, discussion of the risk of CB is an important component of informed consent for salvage reirradiation.« less

  12. SU-E-T-629: Feasibility Study of Treating Multiple Brain Tumors with Large Number of Noncoplanar IMRT Beams

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Dong, P; Ma, L

    Purpose: To study the feasibility of treating multiple brain tumors withlarge number of noncoplanar IMRT beams. Methods: Thirty beams are selected from 390 deliverable beams separated by six degree in 4pi space. Beam selection optimization is based on a column generation algorithm. MLC leaf size is 2 mm. Dose matrices are calculated with collapsed cone convolution and superposition method in a 2 mm by 2mm by 2 mm grid. Twelve brain tumors of various shapes, sizes and locations are used to generate four plans treating 3, 6, 9 and 12 tumors. The radiation dose was 20 Gy prescribed to themore » 100% isodose line. Dose Volume Histograms for tumor and brain were compared. Results: All results are based on a 2 mm by 2 mm by 2 mm CT grid. For 3, 6, 9 and 12 tumor plans, minimum tumor doses are all 20 Gy. Mean tumor dose are 20.0, 20.1, 20.1 and 20.1 Gy. Maximum tumor dose are 23.3, 23.6, 25.4 and 25.4 Gy. Mean ventricles dose are 0.7, 1.7, 2.4 and 3.1 Gy.Mean subventricular zone dose are 0.8, 1.3, 2.2 and 3.2 Gy. Average Equivalent uniform dose (gEUD) values for tumor are 20.1, 20.1, 20.2 and 20.2 Gy. The conformity index (CI) values are close to 1 for all 4 plans. The gradient index (GI) values are 2.50, 2.05, 2.09 and 2.19. Conclusion: Compared with published Gamma Knife treatment studies, noncoplanar IMRT treatment plan is superior in terms of dose conformity. Due to maximum limit of beams per plan, Gamma knife has to treat multiple tumors separately in different plans. Noncoplanar IMRT plans theoretically can be delivered in a single plan on any modern linac with an automated couch and image guidance. This warrants further study of using noncoplanar IMRT as a viable treatment solution for multiple brain tumors.« less

  13. SU-C-BRC-04: Efficient Dose Calculation Algorithm for FFF IMRT with a Simplified Bivariate Gaussian Source Model

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Li, F; Park, J; Barraclough, B

    2016-06-15

    Purpose: To develop an efficient and accurate independent dose calculation algorithm with a simplified analytical source model for the quality assurance and safe delivery of Flattening Filter Free (FFF)-IMRT on an Elekta Versa HD. Methods: The source model consisted of a point source and a 2D bivariate Gaussian source, respectively modeling the primary photons and the combined effect of head scatter, monitor chamber backscatter and collimator exchange effect. The in-air fluence was firstly calculated by back-projecting the edges of beam defining devices onto the source plane and integrating the visible source distribution. The effect of the rounded MLC leaf end,more » tongue-and-groove and interleaf transmission was taken into account in the back-projection. The in-air fluence was then modified with a fourth degree polynomial modeling the cone-shaped dose distribution of FFF beams. Planar dose distribution was obtained by convolving the in-air fluence with a dose deposition kernel (DDK) consisting of the sum of three 2D Gaussian functions. The parameters of the source model and the DDK were commissioned using measured in-air output factors (Sc) and cross beam profiles, respectively. A novel method was used to eliminate the volume averaging effect of ion chambers in determining the DDK. Planar dose distributions of five head-and-neck FFF-IMRT plans were calculated and compared against measurements performed with a 2D diode array (MapCHECK™) to validate the accuracy of the algorithm. Results: The proposed source model predicted Sc for both 6MV and 10MV with an accuracy better than 0.1%. With a stringent gamma criterion (2%/2mm/local difference), the passing rate of the FFF-IMRT dose calculation was 97.2±2.6%. Conclusion: The removal of the flattening filter represents a simplification of the head structure which allows the use of a simpler source model for very accurate dose calculation. The proposed algorithm offers an effective way to ensure the safe delivery

  14. TU-G-BRB-01: Continuous Path Optimization for Non-Coplanar Variant SAD IMRT Delivery Using C-Arm Machines.

    PubMed

    Ruan, D; Dong, P; Low, D; Sheng, K

    2012-06-01

    To develop and investigate a continuous path optimization methodology to traverse prescribed non-coplanar IMRT beams with variant SADs, by orchestrating the couch and gantry movement with zero-collision, minimal patient motion consequence and machine travel time. We convert the given collision zone definition and the prescribed beam location/angles to a tumor-centric coordinate, and represent the traversing path as a continuous open curve. We proceed to optimize a composite objective function consisting of (1) a strong attraction energy to ensure all prescribed beams are en-route, (2) a penalty for patient-motion inducing couch motion, and (3) a penalty for travel-time inducing overall path-length. Feasibility manifold is defined as complement to collision zone and the optimization is performed with a level set representation evolved with variational flows. The proposed method has been implemented and tested on clinically derived data. In the absence of any existing solutions for the same problem, we validate by: (1) visual inspecting the generated path rendered in the 3D tumor-centric coordinates, and (2) comparing with a traveling-salesman (TSP) solution obtained from relaxing the variant SADs and continuous collision-avoidance requirement. The proposed method has generated delivery paths that are smooth and intuitively appealing. Under relaxed settings, our results outperform the generic TSP solutions and agree with specially tuned versions. We have proposed a novel systematic approach that automatically determines the continuous path to cover non-coplanar, varying SAD IMRT beams. The proposed approach accommodates patient-specific collision zone definition and ensures its avoidance continuously. The differential penalty to couch and gantry motions allows customizable tradeoff between patient geometry stability and delivery efficiency. This development paves the path to achieve safe, accurate and efficient non-coplanar IMRT delivery with the advanced robotic

  15. SU-F-BRE-01: A Rapid Method to Determine An Upper Limit On a Radiation Detector's Correction Factor During the QA of IMRT Plans

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kamio, Y; Bouchard, H

    2014-06-15

    Purpose: Discrepancies in the verification of the absorbed dose to water from an IMRT plan using a radiation dosimeter can be wither caused by 1) detector specific nonstandard field correction factors as described by the formalism of Alfonso et al. 2) inaccurate delivery of the DQA plan. The aim of this work is to develop a simple/fast method to determine an upper limit on the contribution of composite field correction factors to these discrepancies. Methods: Indices that characterize the non-flatness of the symmetrised collapsed delivery (VSC) of IMRT fields over detector-specific regions of interest were shown to be correlated withmore » IMRT field correction factors. The indices introduced are the uniformity index (UI) and the mean fluctuation index (MF). Each one of these correlation plots have 10 000 fields generated with a stochastic model. A total of eight radiation detectors were investigated in the radial orientation. An upper bound on the correction factors was evaluated by fitting values of high correction factors for a given index value. Results: These fitted curves can be used to compare the performance of radiation dosimeters in composite IMRT fields. Highly water-equivalent dosimeters like the scintillating detector (Exradin W1) and a generic alanine detector have been found to have corrections under 1% over a broad range of field modulations (0 – 0.12 for MF and 0 – 0.5 for UI). Other detectors have been shown to have corrections of a few percent over this range. Finally, a full Monte Carlo simulations of 18 clinical and nonclinical IMRT field showed good agreement with the fitted curve for the A12 ionization chamber. Conclusion: This work proposes a rapid method to evaluate an upper bound on the contribution of correction factors to discrepancies found in the verification of DQA plans.« less

  16. Rectal balloon use limits vaginal displacement, rectal dose, and rectal toxicity in patients receiving IMRT for postoperative gynecological malignancies.

    PubMed

    Wu, Cheng-Chia; Wuu, Yen-Ruh; Yanagihara, Theodore; Jani, Ashish; Xanthopoulos, Eric P; Tiwari, Akhil; Wright, Jason D; Burke, William M; Hou, June Y; Tergas, Ana I; Deutsch, Israel

    2018-01-01

    Pelvic radiotherapy for gynecologic malignancies traditionally used a 4-field box technique. Later trials have shown the feasibility of using intensity-modulated radiotherapy (IMRT) instead. But vaginal movement between fractions is concerning when using IMRT due to greater conformality of the isodose curves to the target and the resulting possibility of missing the target while the vagina is displaced. In this study, we showed that the use of a rectal balloon during treatment can decrease vaginal displacement, limit rectal dose, and limit acute and late toxicities. Little is known regarding the use of a rectal balloon (RB) in treating patients with IMRT in the posthysterectomy setting. We hypothesize that the use of an RB during treatment can limit rectal dose and acute and long-term toxicities, as well as decrease vaginal cuff displacement between fractions. We performed a retrospective review of patients with gynecological malignancies who received postoperative IMRT with the use of an RB from January 1, 2012 to January 1, 2015. Rectal dose constraint was examined as per Radiation Therapy Oncology Group (RTOG) 1203 and 0418. Daily cone beam computed tomography (CT) was performed, and the average (avg) displacement, avg magnitude, and avg magnitude of vector were calculated. Toxicity was reported according to RTOG acute radiation morbidity scoring criteria. Acute toxicity was defined as less than 90 days from the end of radiation treatment. Late toxicity was defined as at least 90 days after completing radiation. Twenty-eight patients with postoperative IMRT with the use of an RB were examined and 23 treatment plans were reviewed. The avg rectal V40 was 39.3% ± 9.0%. V30 was65.1% ± 10.0%. V50 was 0%. Separate cone beam computed tomography (CBCT) images (n = 663) were reviewed. The avg displacement was as follows: superior 0.4 + 2.99 mm, left 0.23 ± 4.97 mm, and anterior 0.16 ± 5.18 mm. The avg magnitude of displacement was superior

  17. Development of independent MU/treatment time verification algorithm for non-IMRT treatment planning: A clinical experience

    NASA Astrophysics Data System (ADS)

    Tatli, Hamza; Yucel, Derya; Yilmaz, Sercan; Fayda, Merdan

    2018-02-01

    The aim of this study is to develop an algorithm for independent MU/treatment time (TT) verification for non-IMRT treatment plans, as a part of QA program to ensure treatment delivery accuracy. Two radiotherapy delivery units and their treatment planning systems (TPS) were commissioned in Liv Hospital Radiation Medicine Center, Tbilisi, Georgia. Beam data were collected according to vendors' collection guidelines, and AAPM reports recommendations, and processed by Microsoft Excel during in-house algorithm development. The algorithm is designed and optimized for calculating SSD and SAD treatment plans, based on AAPM TG114 dose calculation recommendations, coded and embedded in MS Excel spreadsheet, as a preliminary verification algorithm (VA). Treatment verification plans were created by TPSs based on IAEA TRS 430 recommendations, also calculated by VA, and point measurements were collected by solid water phantom, and compared. Study showed that, in-house VA can be used for non-IMRT plans MU/TT verifications.

  18. Adjuvant helical IMRT by tomotherapy for bulky adrenocortical carcinoma operated with positive margins: a case report.

    PubMed

    Delmastro, Elena; Garibaldi, Elisabetta; Gabriele, Domenico; Bresciani, Sara; Cattari, Gabriella; Dia, Amalia Di; Manini, Claudia; Collura, Devis; Redda, Maria Grazia Ruo; Gabriele, Pietro

    2016-11-11

    Adrenocortical carcinoma (ACC) is a rare tumor in the adult. The main therapy is surgery but in some cases radiotherapy may be needed to control the disease locally. A patient with a surgically removed bulky ACC and pathologic finding of a positive margin was treated at our center by adjuvant mitotane and radiotherapy using an intensity-modulated radiation therapy (IMRT)/image-guided radiotherapy (IGRT) technique by tomotherapy. Dose prescriptions were 63 Gy on the surgical bed and 50.4 Gy on the lymphatic drainage in 28 sessions. Patient compliance was good with no evidence of acute or late toxicities. Thirty months after radiotherapy, the patient is alive without evidence of disease checked by 18F-fluorodeoxyglucose positron emission tomography/computed tomography and without any complication. In patients with adverse prognostic features, the delivery of adequate adjuvant radiotherapy doses with IMRT and daily IGRT is feasible and safe and could result in an improved outcome for patients with ACC.

  19. Volumetric modulation arc radiotherapy with flattening filter-free beams compared with static gantry IMRT and 3D conformal radiotherapy for advanced esophageal cancer: a feasibility study.

    PubMed

    Nicolini, Giorgia; Ghosh-Laskar, Sarbani; Shrivastava, Shyam Kishore; Banerjee, Sushovan; Chaudhary, Suresh; Agarwal, Jai Prakash; Munshi, Anusheel; Clivio, Alessandro; Fogliata, Antonella; Mancosu, Pietro; Vanetti, Eugenio; Cozzi, Luca

    2012-10-01

    A feasibility study was performed to evaluate RapidArc (RA), and the potential benefit of flattening filter-free beams, on advanced esophageal cancer against intensity-modulated radiotherapy (IMRT) and three-dimensional conformal radiotherapy (3D-CRT). The plans for 3D-CRT and IMRT with three to seven and five to seven fixed beams were compared against double-modulated arcs with avoidance sectors to spare the lungs for 10 patients. All plans were optimized for 6-MV photon beams. The RA plans were studied for conventional and flattening filter-free (FFF) beams. The objectives for the planning target volume were the volume receiving ≥ 95% or at most 107% of the prescribed dose of <1% with a dose prescription of 59.4 Gy. For the organs at risk, the lung volume (minus the planning target volume) receiving ≥ 5 Gy was <60%, that receiving 20 Gy was <20%-30%, and the mean lung dose was <15.0 Gy. The heart volume receiving 45 Gy was <20%, volume receiving 30 Gy was <50%. The spinal dose received by 1% was <45 Gy. The technical delivery parameters for RA were assessed to compare the normal and FFF beam characteristics. RA and IMRT provided equivalent coverage and homogeneity, slightly superior to 3D-CRT. The conformity index was 1.2 ± 0.1 for RA and IMRT and 1.5 ± 0.2 for 3D-CRT. The mean lung dose was 12.2 ± 4.5 for IMRT, 11.3 ± 4.6 for RA, and 10.8 ± 4.4 for RA with FFF beams, 18.2 ± 8.5 for 3D-CRT. The percentage of volume receiving ≥ 20 Gy ranged from 23.6% ± 9.1% to 21.1% ± 9.7% for IMRT and RA (FFF beams) and 39.2% ± 17.0% for 3D-CRT. The heart and spine objectives were met by all techniques. The monitor units for IMRT and RA were 457 ± 139, 322 ± 20, and 387 ± 40, respectively. RA with FFF beams showed, compared with RA with normal beams, a ∼20% increase in monitor units per Gray, a 90% increase in the average dose rate, and 20% reduction in beam on time (owing to different gantry speeds). RA demonstrated, compared with conventional IMRT, a

  20. Effect of patient setup errors on simultaneously integrated boost head and neck IMRT treatment plans

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Siebers, Jeffrey V.; Keall, Paul J.; Wu Qiuwen

    2005-10-01

    Purpose: The purpose of this study is to determine dose delivery errors that could result from random and systematic setup errors for head-and-neck patients treated using the simultaneous integrated boost (SIB)-intensity-modulated radiation therapy (IMRT) technique. Methods and Materials: Twenty-four patients who participated in an intramural Phase I/II parotid-sparing IMRT dose-escalation protocol using the SIB treatment technique had their dose distributions reevaluated to assess the impact of random and systematic setup errors. The dosimetric effect of random setup error was simulated by convolving the two-dimensional fluence distribution of each beam with the random setup error probability density distribution. Random setup errorsmore » of {sigma} = 1, 3, and 5 mm were simulated. Systematic setup errors were simulated by randomly shifting the patient isocenter along each of the three Cartesian axes, with each shift selected from a normal distribution. Systematic setup error distributions with {sigma} = 1.5 and 3.0 mm along each axis were simulated. Combined systematic and random setup errors were simulated for {sigma} = {sigma} = 1.5 and 3.0 mm along each axis. For each dose calculation, the gross tumor volume (GTV) received by 98% of the volume (D{sub 98}), clinical target volume (CTV) D{sub 90}, nodes D{sub 90}, cord D{sub 2}, and parotid D{sub 50} and parotid mean dose were evaluated with respect to the plan used for treatment for the structure dose and for an effective planning target volume (PTV) with a 3-mm margin. Results: Simultaneous integrated boost-IMRT head-and-neck treatment plans were found to be less sensitive to random setup errors than to systematic setup errors. For random-only errors, errors exceeded 3% only when the random setup error {sigma} exceeded 3 mm. Simulated systematic setup errors with {sigma} = 1.5 mm resulted in approximately 10% of plan having more than a 3% dose error, whereas a {sigma} = 3.0 mm resulted in half of the plans

  1. Accelerated partial breast irradiation using intensity-modulated radiotherapy versus whole breast irradiation: 5-year survival analysis of a phase 3 randomised controlled trial.

    PubMed

    Livi, Lorenzo; Meattini, Icro; Marrazzo, Livia; Simontacchi, Gabriele; Pallotta, Stefania; Saieva, Calogero; Paiar, Fabiola; Scotti, Vieri; De Luca Cardillo, Carla; Bastiani, Paolo; Orzalesi, Lorenzo; Casella, Donato; Sanchez, Luis; Nori, Jacopo; Fambrini, Massimiliano; Bianchi, Simonetta

    2015-03-01

    Accelerated partial breast irradiation (APBI) has been introduced as an alternative treatment method for selected patients with early stage breast cancer (BC). Intensity-modulated radiotherapy (IMRT) has the theoretical advantage of a further increase in dose conformity compared with three-dimensional techniques, with more normal tissue sparing. The aim of this randomised trial is to compare the local recurrence and survival of APBI using the IMRT technique after breast-conserving surgery to conventional whole-breast irradiation (WBI) in early stage BC. This study was performed at the University of Florence (Florence, Italy). Women aged more than 40years affected by early BC, with a maximum pathological tumour size of 25mm, were randomly assigned in a 1:1 ratio to receive either WBI or APBI using IMRT. Patients in the APBI arm received a total dose of 30 Gy to the tumour bed in five daily fractions. The WBI arm received 50Gy in 25 fractions, followed by a boost on the tumour bed of 10Gy in five fractions. The primary end-point was occurrence of ipsilateral breast tumour recurrences (IBTRs); the main analysis was by intention-to-treat. This trial is registered with ClinicalTrials.gov, number NCT02104895. A total of 520 patients were randomised (260 to external WBI and 260 to APBI with IMRT) between March 2005 and June 2013. At a median follow-up of 5.0 years (Interquartile Range (IQR) 3.4-7.0), the IBTR rate was 1.5% (three cases) in the APBI group (95% confidence interval (CI) 0.1-3.0) and in the WBI group (three cases; 95% CI 0.0-2.8). No significant difference emerged between the two groups (log rank test p=0.86). We identified seven deaths in the WBI group and only one in the APBI group (p=0.057). The 5-year overall survival was 96.6% for the WBI group and 99.4% for the APBI group. The APBI group presented significantly better results considering acute (p=0.0001), late (p=0.004), and cosmetic outcome (p=0.045). To our knowledge, this is the first randomised

  2. Quality of life after parotid-sparing IMRT for head-and-neck cancer: a prospective longitudinal study.

    PubMed

    Lin, Alexander; Kim, Hyungjin M; Terrell, Jeffrey E; Dawson, Laura A; Ship, Jonathan A; Eisbruch, Avraham

    2003-09-01

    Parotid-sparing intensity-modulated radiotherapy (IMRT) for head-and-neck cancer reduces xerostomia compared with standard RT. To assess potential improvements in broader aspects of quality of life (QOL), we initiated a study of patient-reported QOL and its predictors after IMRT. This was a prospective longitudinal study of head-and-neck cancer patients receiving multisegmental static IMRT. Patients were given a validated xerostomia questionnaire (XQ), and a validated head-and-neck cancer-related QOL questionnaire consisting of four multi-item domains: Eating, Communication, Pain, and Emotion. The Eating domain contains one question (total of six) asking directly about xerostomia. In both questionnaires, higher scores denote worse symptoms or QOL. The questionnaires and measurements of salivary output from the major glands were completed before RT started (pre-RT) and at 3, 6, and 12 months after RT. The association between the QOL scores and patient-, tumor-, and therapy-related factors was assessed using the random effects model. Thirty-six patients participating in the study completed the questionnaires through 12 months. The XQ scores worsened significantly at 3 months compared with the pre-RT scores, but later they improved gradually through 12 months (p = 0.003), in parallel with an increase in the salivary output from the spared salivary glands. The QOL summary scores were stable between the baseline (pre-RT) and 3 months after RT scores. Patients receiving postoperative RT (whose pre-RT questionnaires were taken a few weeks after surgery) tended to have improved scores after RT, reflecting the subsidence of acute postoperative sequelae, compared with a tendency toward worsened scores in patients receiving definitive RT. After 3 months, statistically significant improvement was noted in the summary QOL scores for all patients, through 12 months after RT (p = 0.01). The salivary flow rates, tumor doses, mean oral cavity dose, age, gender, sites or stages of

  3. Feasibility of CBCT dosimetry for IMRT using a normoxic polymethacrylic-acid gel dosimeter

    NASA Astrophysics Data System (ADS)

    Bong, Ji Hye; Kwon, Soo-Il; Kim, Kum Bae; Kim, Mi Suk; Jung, Hai Jo; Ji, Young Hoon; Ko, In Ok; Park, Ji Ae; Kim, Kyeong Min

    2013-09-01

    The purpose of this study is to evaluate the availability of cone-beam computed tomography(CBCT) for gel dosimetry. The absorbed dose was analyzed by using intensity-modulated radiation therapy(IMRT) to irradiate several tumor shapes with a calculated dose and several tumor acquiring images with CBCT in order to verify the possibility of reading a dose on the polymer gel dosimeter by means of the CBCT image. The results were compared with those obtained using magnetic resonance imaging(MRI) and CT. The linear correlation coefficients at doses less than 10 Gy for the polymer gel dosimeter were 0.967, 0.933 and 0.985 for MRI, CT and CBCT, respectively. The dose profile was symmetric on the basis of the vertical axis in a circular shape, and the uniformity was 2.50% for the MRI and 8.73% for both the CT and the CBCT. In addition, the gradient in the MR image of the gel dosimeter irradiated in an H shape was 109.88 while the gradients of the CT and the CBCT were 71.95 and 14.62, respectively. Based on better image quality, the present study showed that CBCT dosimetry for IMRT could be restrictively performed using a normoxic polymethacrylic-acid gel dosimeter.

  4. Direct aperture optimization: a turnkey solution for step-and-shoot IMRT.

    PubMed

    Shepard, D M; Earl, M A; Li, X A; Naqvi, S; Yu, C

    2002-06-01

    IMRT treatment plans for step-and-shoot delivery have traditionally been produced through the optimization of intensity distributions (or maps) for each beam angle. The optimization step is followed by the application of a leaf-sequencing algorithm that translates each intensity map into a set of deliverable aperture shapes. In this article, we introduce an automated planning system in which we bypass the traditional intensity optimization, and instead directly optimize the shapes and the weights of the apertures. We call this approach "direct aperture optimization." This technique allows the user to specify the maximum number of apertures per beam direction, and hence provides significant control over the complexity of the treatment delivery. This is possible because the machine dependent delivery constraints imposed by the MLC are enforced within the aperture optimization algorithm rather than in a separate leaf-sequencing step. The leaf settings and the aperture intensities are optimized simultaneously using a simulated annealing algorithm. We have tested direct aperture optimization on a variety of patient cases using the EGS4/BEAM Monte Carlo package for our dose calculation engine. The results demonstrate that direct aperture optimization can produce highly conformal step-and-shoot treatment plans using only three to five apertures per beam direction. As compared with traditional optimization strategies, our studies demonstrate that direct aperture optimization can result in a significant reduction in both the number of beam segments and the number of monitor units. Direct aperture optimization therefore produces highly efficient treatment deliveries that maintain the full dosimetric benefits of IMRT.

  5. SU-E-T-29: A Web Application for GPU-Based Monte Carlo IMRT/VMAT QA with Delivered Dose Verification

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Folkerts, M; University of California, San Diego, La Jolla, CA; Graves, Y

    Purpose: To enable an existing web application for GPU-based Monte Carlo (MC) 3D dosimetry quality assurance (QA) to compute “delivered dose” from linac logfile data. Methods: We added significant features to an IMRT/VMAT QA web application which is based on existing technologies (HTML5, Python, and Django). This tool interfaces with python, c-code libraries, and command line-based GPU applications to perform a MC-based IMRT/VMAT QA. The web app automates many complicated aspects of interfacing clinical DICOM and logfile data with cutting-edge GPU software to run a MC dose calculation. The resultant web app is powerful, easy to use, and is ablemore » to re-compute both plan dose (from DICOM data) and delivered dose (from logfile data). Both dynalog and trajectorylog file formats are supported. Users upload zipped DICOM RP, CT, and RD data and set the expected statistic uncertainty for the MC dose calculation. A 3D gamma index map, 3D dose distribution, gamma histogram, dosimetric statistics, and DVH curves are displayed to the user. Additional the user may upload the delivery logfile data from the linac to compute a 'delivered dose' calculation and corresponding gamma tests. A comprehensive PDF QA report summarizing the results can also be downloaded. Results: We successfully improved a web app for a GPU-based QA tool that consists of logfile parcing, fluence map generation, CT image processing, GPU based MC dose calculation, gamma index calculation, and DVH calculation. The result is an IMRT and VMAT QA tool that conducts an independent dose calculation for a given treatment plan and delivery log file. The system takes both DICOM data and logfile data to compute plan dose and delivered dose respectively. Conclusion: We sucessfully improved a GPU-based MC QA tool to allow for logfile dose calculation. The high efficiency and accessibility will greatly facilitate IMRT and VMAT QA.« less

  6. Evaluation of the effect of patient dose from cone beam computed tomography on prostate IMRT using Monte Carlo simulation.

    PubMed

    Chow, James C L; Leung, Michael K K; Islam, Mohammad K; Norrlinger, Bernhard D; Jaffray, David A

    2008-01-01

    The aim of this study is to evaluate the impact of the patient dose due to the kilovoltage cone beam computed tomography (kV-CBCT) in a prostate intensity-modulated radiation therapy (IMRT). The dose distributions for the five prostate IMRTs were calculated using the Pinnacle treatment planning system. To calculate the patient dose from CBCT, phase-space beams of a CBCT head based on the ELEKTA x-ray volume imaging system were generated using the Monte Carlo BEAMnr code for 100, 120, 130, and 140 kVp energies. An in-house graphical user interface called DOSCTP (DOSXYZnrc-based) developed using MATLAB was used to calculate the dose distributions due to a 360 degrees photon arc from the CBCT beam with the same patient CT image sets as used in Pinnacle. The two calculated dose distributions were added together by setting the CBCT doses equal to 1%, 1.5%, 2%, and 2.5% of the prescription dose of the prostate IMRT. The prostate plan and the summed dose distributions were then processed in the CERR platform to determine the dose-volume histograms (DVHs) of the regions of interest. Moreover, dose profiles along the x- and y-axes crossing the isocenter with and without addition of the CBCT dose were determined. It was found that the added doses due to CBCT are most significant at the femur heads. Higher doses were found at the bones for a relatively low energy CBCT beam such as 100 kVp. Apart from the bones, the CBCT dose was observed to be most concentrated on the anterior and posterior side of the patient anatomy. Analysis of the DVHs for the prostate and other critical tissues showed that they vary only slightly with the added CBCT dose at different beam energies. On the other hand, the changes of the DVHs for the femur heads due to the CBCT dose and beam energy were more significant than those of rectal and bladder wall. By analyzing the vertical and horizontal dose profiles crossing the femur heads and isocenter, with and without the CBCT dose equal to 2% of the

  7. TH-EF-BRB-05: 4pi Non-Coplanar IMRT Beam Angle Selection by Convex Optimization with Group Sparsity Penalty

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    O’Connor, D; Nguyen, D; Voronenko, Y

    Purpose: Integrated beam orientation and fluence map optimization is expected to be the foundation of robust automated planning but existing heuristic methods do not promise global optimality. We aim to develop a new method for beam angle selection in 4π non-coplanar IMRT systems based on solving (globally) a single convex optimization problem, and to demonstrate the effectiveness of the method by comparison with a state of the art column generation method for 4π beam angle selection. Methods: The beam angle selection problem is formulated as a large scale convex fluence map optimization problem with an additional group sparsity term thatmore » encourages most candidate beams to be inactive. The optimization problem is solved using an accelerated first-order method, the Fast Iterative Shrinkage-Thresholding Algorithm (FISTA). The beam angle selection and fluence map optimization algorithm is used to create non-coplanar 4π treatment plans for several cases (including head and neck, lung, and prostate cases) and the resulting treatment plans are compared with 4π treatment plans created using the column generation algorithm. Results: In our experiments the treatment plans created using the group sparsity method meet or exceed the dosimetric quality of plans created using the column generation algorithm, which was shown superior to clinical plans. Moreover, the group sparsity approach converges in about 3 minutes in these cases, as compared with runtimes of a few hours for the column generation method. Conclusion: This work demonstrates the first non-greedy approach to non-coplanar beam angle selection, based on convex optimization, for 4π IMRT systems. The method given here improves both treatment plan quality and runtime as compared with a state of the art column generation algorithm. When the group sparsity term is set to zero, we obtain an excellent method for fluence map optimization, useful when beam angles have already been selected. NIH R43CA183390, NIH

  8. Experimental verification of the Acuros XB and AAA dose calculation adjacent to heterogeneous media for IMRT and RapidArc of nasopharygeal carcinoma.

    PubMed

    Kan, Monica W K; Leung, Lucullus H T; So, Ronald W K; Yu, Peter K N

    2013-03-01

    To compare the doses calculated by the Acuros XB (AXB) algorithm and analytical anisotropic algorithm (AAA) with experimentally measured data adjacent to and within heterogeneous medium using intensity modulated radiation therapy (IMRT) and RapidArc(®) (RA) volumetric arc therapy plans for nasopharygeal carcinoma (NPC). Two-dimensional dose distribution immediately adjacent to both air and bone inserts of a rectangular tissue equivalent phantom irradiated using IMRT and RA plans for NPC cases were measured with GafChromic(®) EBT3 films. Doses near and within the nasopharygeal (NP) region of an anthropomorphic phantom containing heterogeneous medium were also measured with thermoluminescent dosimeters (TLD) and EBT3 films. The measured data were then compared with the data calculated by AAA and AXB. For AXB, dose calculations were performed using both dose-to-medium (AXB_Dm) and dose-to-water (AXB_Dw) options. Furthermore, target dose differences between AAA and AXB were analyzed for the corresponding real patients. The comparison of real patient plans was performed by stratifying the targets into components of different densities, including tissue, bone, and air. For the verification of planar dose distribution adjacent to air and bone using the rectangular phantom, the percentages of pixels that passed the gamma analysis with the ± 3%/3mm criteria were 98.7%, 99.5%, and 97.7% on the axial plane for AAA, AXB_Dm, and AXB_Dw, respectively, averaged over all IMRT and RA plans, while they were 97.6%, 98.2%, and 97.7%, respectively, on the coronal plane. For the verification of planar dose distribution within the NP region of the anthropomorphic phantom, the percentages of pixels that passed the gamma analysis with the ± 3%/3mm criteria were 95.1%, 91.3%, and 99.0% for AAA, AXB_Dm, and AXB_Dw, respectively, averaged over all IMRT and RA plans. Within the NP region where air and bone were present, the film measurements represented the dose close to unit density water

  9. Evaluation of dosimetric properties of 6 MV & 10 MV photon beams from a linear accelerator with no flattening filter

    NASA Astrophysics Data System (ADS)

    Pearson, David

    A linear accelerator manufactured by Elekta, equipped with a multi leaf collimation (MLC) system has been modelled using Monte Carlo simulations with the photon flattening filter removed. The purpose of this investigation was to show that more efficient and more accurate Intensity Modulated Radiation Therapy (IMRT) treatments can be delivered from a standard linear accelerator with the flattening filter removed from the beam. A range of simulations of 6 MV and 10 MV photon were studied and compared to a model of a standard accelerator which included the flattening filter for those beams. Measurements using a scanning water phantom were also performed after the flattening filter had been removed. We show here that with the flattening filter removed, an increase to the dose on the central axis by a factor of 2.35 and 4.18 is achieved for 6 MV and 10 MV photon beams respectively using a standard 10x 10cm2 field size. A comparison of the dose at points at the field edges led to the result that, removal of the flattening filter reduced the dose at these points by approximately 10% for the 6 MV beam over the clinical range of field sizes. A further consequence of removing the flattening filter was the softening of the photon energy spectrum leading to a steeper reduction in dose at depths greater than dmax. Also studied was the electron contamination brought about by the removal of the filter. To reduce this electron contamination and thus reduce the skin dose to the patient we consider the use of an electron scattering foil in the beam path. The electron scattering foil had very little effect on dmax. From simulations of a standard 6MV beam, a filter-free beam and a filter-free beam with electron scattering foil, we deduce that the proportion of electrons in the photon beam is 0.35%, 0.28% and 0.27%, consecutively. In short, higher dose rates will result in decreased treatment times and the reduced dose outside of the field is indicative of reducing the dose to the

  10. SU-F-T-238: Analyzing the Performance of MapCHECK2 and Delta4 Quality Assurance Phantoms in IMRT and VMAT Plans

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Lu, SH; Tsai, YC; Lan, HT

    2016-06-15

    Purpose: Intensity-modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT) have been widely investigated for use in radiotherapy and found to have a highly conformal dose distribution. Delta{sup 4} is a novel cylindrical phantom consisting of 1069 p-type diodes with true treatments measured in the 3D target volume. The goal of this study was to compare the performance of a Delta{sup 4} diode array for IMRT and VMAT planning with ion chamber and MapCHECK2. Methods: Fifty-four IMRT (n=9) and VMAT (n=45) plans were imported to Philips Pinnacle Planning System 9.2 for recalculation with a solid water phantom, MapCHECK2, and themore » Delta4 phantom. To evaluate the difference between the measured and calculated dose, we used MapCHECK2 and Delta{sup 4} for a dose-map comparison and an ion chamber (PTW 31010 Semiflex 0.125 cc) for a point-dose comparison. Results: All 54 plans met the criteria of <3% difference for the point dose (at least two points) by ion chamber. The mean difference was 0.784% with a standard deviation of 1.962%. With a criteria of 3 mm/3% in a gamma analysis, the average passing rates were 96.86%±2.19% and 98.42%±1.97% for MapCHECK2 and Delta{sup 4}, respectively. The student t-test of MapCHECK2/Delta{sup 4}, ion chamber/Delta{sup 4}, and ion chamber/MapCHECK2 were 0.0008, 0.2944, and 0.0002, respectively. There was no significant difference in passing rates between MapCHECK2 and Delta{sup 4} for the IMRT plan (p = 0.25). However, a higher pass rate was observed in Delta{sup 4} (98.36%) as compared to MapCHECK2 (96.64%, p < 0.0001) for the VMAT plan. Conclusion: The Pinnacle planning system can accurately calculate doses for VMAT and IMRT plans. The Delta{sup 4} shows a similar result when compared to ion chamber and MapCHECK2, and is an efficient tool for patient-specific quality assurance, especially for rotation therapy.« less

  11. Comparative analysis of SmartArc‐based dual arc volumetric‐modulated arc radiotherapy (VMAT) versus intensity‐modulated radiotherapy (IMRT) for nasopharyngeal carcinoma

    PubMed Central

    Chao, Pei‐Ju; Ting, Hui‐Min; Lo, Su‐Hua; Wang, Yu‐Wen; Tuan, Chiu‐Ching; Fang, Fu‐Min

    2011-01-01

    The purpose of this study was to evaluate and quantify the planning performance of SmartArc‐based volumetric‐modulated arc radiotherapy (VMAT) versus fixed‐beam intensity‐modulated radiotherapy (IMRT) for nasopharyngeal carcinoma (NPC) using a sequential mode treatment plan. The plan quality and performance of dual arc‐VMAT (DA‐VMAT) using the Pinnacle3 Smart‐Arc system (clinical version 9.0; Philips, Fitchburg, WI, USA) were evaluated and compared with those of seven‐field (7F)‐IMRT in 18 consecutive NPC patients. Analysis parameters included the conformity index (CI) and homogeneity index (HI) for the planning target volume (PTV), maximum and mean dose, normal tissue complication probability (NTCP) for the specified organs at risk (OARs), and comprehensive quality index (CQI) for an overall evaluation in the 11 OARs. Treatment delivery time, monitor units per fraction (MU/fr), and gamma (Γ3mm,3%) evaluations were also analyzed. DA‐VMAT achieved similar target coverage and slightly better homogeneity than conventional 7F‐IMRT with a similar CI and HI. NTCP values were only significantly lower in the left parotid gland (for xerostomia) for DA‐VMAT plans. The mean value of CQI at 0.98±0.02 indicated a 2% benefit in sparing OARs by DA‐VMAT. The MU/fr used and average delivery times appeared to show improved efficiencies in DA‐VMAT. Each technique demonstrated high accuracy in dose delivery in terms of a high‐quality assurance (QA) passing rate (>98%) of the (Γ3mm,3%) criterion. The major difference between DA‐VMAT and 7F‐IMRT using a sequential mode for treating NPC cases appears to be improved efficiency, resulting in a faster delivery time and the use of fewer MU/fr. PACS number: 87.53.Tf, 87.55.x, 87.55.D, 87.55.dk PMID:22089015

  12. SU-E-T-479: IMRT Plan Recalculation in Patient Based On Dynalog Data and the Effect of a Single Failing MLC Motor

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Morcos, M; Mitrou, E

    2015-06-15

    Purpose: Using Linac dynamic logs (Dynalogs) we evaluate the impact of a single failing MLC motor on the deliverability of an IMRT plan by assessing the recalculated dose volume histograms (DVHs) taking the delivered MLC positions and beam hold-offs into consideration. Methods: This is a retrospective study based on a deteriorating MLC motor (leaf 36B) which was observed to be failing via Dynalog analysis. To investigate further, Eclipse-importable MLC files were generated from Dynalogs to recalculate the actual delivered dose and to assess the clinical impact through DVHs. All deliveries were performed on a Varian 21EX linear accelerator equipped withmore » Millennium-120 MLC. The analysis of Dynalog files and subsequent conversion to Eclipse-importable MLC files were all performed by in-house programming in Python. Effects on plan DVH are presented in the following section on a particular brain-IMRT plan which was delivered with a failing MLC motor which was then replaced. Results: Global max dose increased by 13.5%, max dose to the brainstem PRV increased by 8.2%, max dose to the optic chiasm increased by 7.6%, max dose to optic nerve increased by 8.8% and the mean dose to the PTV increased by 7.9% when comparing the original plan to the fraction with the failing MLC motor. The reason the dose increased was due to the failure being on the B-bank which is the lagging side on a sliding window delivery, therefore any failures on this side will cause an over-irradiation as the B-bank leaves struggles to keep the window from growing. Conclusion: Our findings suggest that a single failing MLC motor may jeopardize the entire delivery. This may be due to the bad MLC motor drawing too much current causing all MLCs on the same bank to underperform. This hypothesis will be investigated in a future study.« less

  13. SU-E-T-621: Planning Methodologies for Cancer of the Anal Canal: Comparing IMRT, Rapid Arc, and Pencil Beam Scanning Proton Beam

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    McGlade, J; Kassaee, A

    2015-06-15

    Purpose: To evaluate planning methods for anal canal cancer and compare the results of 9-field Intensity Modulated Radiotherapy (IMRT), Volumetric Modulated Arc Therapy (Varian, RapidArc), and Proton Pencil Beam Scanning (PBS). Methods: We generated plans with IMRT, RapidArc (RA) and PBS for twenty patients for both initial phase including nodes and cone down phase of treatment using Eclipe (Varian). We evaluated the advantage of each technique for each phase. RA plans used 2 to 4 arcs and various collimator orientations. PBS used two posterior oblique fields. We evaluated the plans comparing dose volume histogram (DVH), locations of hot spots, andmore » PTV dose conformity. Results: Due to complex shape of target, for RA plans, multiple arcs (>2) are required to achieve optimal PTV conformity. When the PTV exceeds 15 cm in the superior-inferior direction, limitations of deliverability start to dominate. The PTV should be divided into a superior and an inferior structure. The optimization is performed with fixed jaws for each structure and collimator set to 90 degrees for the inferior PTV. Proton PBS plans show little advantage in small bowel sparing when treating the nodes. However, PBS plan reduces volumetric dose to the bladder at the cost of higher doses to the perineal skin. IMRT plans provide good target conformity, but they generate hot spots outside of the target volume. Conclusion: When using one planning technique for entire course of treatment, Multiple arc (>2) RA plans are better as compared to IMRT and PBS plans. When combining techniques, RA for the initial phase in combination with PBS for the cone down phase results in the most optimal plans.« less

  14. Toward optimizing patient-specific IMRT QA techniques in the accurate detection of dosimetrically acceptable and unacceptable patient plans

    PubMed Central

    McKenzie, Elizabeth M.; Balter, Peter A.; Stingo, Francesco C.; Jones, Jimmy; Followill, David S.; Kry, Stephen F.

    2014-01-01

    Purpose: The authors investigated the performance of several patient-specific intensity-modulated radiation therapy (IMRT) quality assurance (QA) dosimeters in terms of their ability to correctly identify dosimetrically acceptable and unacceptable IMRT patient plans, as determined by an in-house-designed multiple ion chamber phantom used as the gold standard. A further goal was to examine optimal threshold criteria that were consistent and based on the same criteria among the various dosimeters. Methods: The authors used receiver operating characteristic (ROC) curves to determine the sensitivity and specificity of (1) a 2D diode array undergoing anterior irradiation with field-by-field evaluation, (2) a 2D diode array undergoing anterior irradiation with composite evaluation, (3) a 2D diode array using planned irradiation angles with composite evaluation, (4) a helical diode array, (5) radiographic film, and (6) an ion chamber. This was done with a variety of evaluation criteria for a set of 15 dosimetrically unacceptable and 9 acceptable clinical IMRT patient plans, where acceptability was defined on the basis of multiple ion chamber measurements using independent ion chambers and a phantom. The area under the curve (AUC) on the ROC curves was used to compare dosimeter performance across all thresholds. Optimal threshold values were obtained from the ROC curves while incorporating considerations for cost and prevalence of unacceptable plans. Results: Using common clinical acceptance thresholds, most devices performed very poorly in terms of identifying unacceptable plans. Grouping the detector performance based on AUC showed two significantly different groups. The ion chamber, radiographic film, helical diode array, and anterior-delivered composite 2D diode array were in the better-performing group, whereas the anterior-delivered field-by-field and planned gantry angle delivery using the 2D diode array performed less well. Additionally, based on the AUCs, there

  15. Toward optimizing patient-specific IMRT QA techniques in the accurate detection of dosimetrically acceptable and unacceptable patient plans.

    PubMed

    McKenzie, Elizabeth M; Balter, Peter A; Stingo, Francesco C; Jones, Jimmy; Followill, David S; Kry, Stephen F

    2014-12-01

    The authors investigated the performance of several patient-specific intensity-modulated radiation therapy (IMRT) quality assurance (QA) dosimeters in terms of their ability to correctly identify dosimetrically acceptable and unacceptable IMRT patient plans, as determined by an in-house-designed multiple ion chamber phantom used as the gold standard. A further goal was to examine optimal threshold criteria that were consistent and based on the same criteria among the various dosimeters. The authors used receiver operating characteristic (ROC) curves to determine the sensitivity and specificity of (1) a 2D diode array undergoing anterior irradiation with field-by-field evaluation, (2) a 2D diode array undergoing anterior irradiation with composite evaluation, (3) a 2D diode array using planned irradiation angles with composite evaluation, (4) a helical diode array, (5) radiographic film, and (6) an ion chamber. This was done with a variety of evaluation criteria for a set of 15 dosimetrically unacceptable and 9 acceptable clinical IMRT patient plans, where acceptability was defined on the basis of multiple ion chamber measurements using independent ion chambers and a phantom. The area under the curve (AUC) on the ROC curves was used to compare dosimeter performance across all thresholds. Optimal threshold values were obtained from the ROC curves while incorporating considerations for cost and prevalence of unacceptable plans. Using common clinical acceptance thresholds, most devices performed very poorly in terms of identifying unacceptable plans. Grouping the detector performance based on AUC showed two significantly different groups. The ion chamber, radiographic film, helical diode array, and anterior-delivered composite 2D diode array were in the better-performing group, whereas the anterior-delivered field-by-field and planned gantry angle delivery using the 2D diode array performed less well. Additionally, based on the AUCs, there was no significant difference

  16. Dosimetric and radiobiological comparison of Forward Tangent Intensity Modulated Radiation Therapy (FT-IMRT) and Volumetric Modulated Arc Therapy (VMAT) for early stage whole breast cancer

    NASA Astrophysics Data System (ADS)

    Moshiri Sedeh, Nader

    Intensity Modulated Radiation Therapy (IMRT) is a well-known type of external beam radiation therapy. The advancement in technology has had an inevitable influence in radiation oncology as well that has led to a newer and faster dose delivery technique called Volumetric Modulated Arc Therapy (VMAT). Since the presence of the VMAT modality in clinics in the late 2000, there have been many studies in order to compare the results of the VMAT modality with the current popular modality IMRT for various tumor sites in the body such as brain, prostate, head and neck, cervix and anal carcinoma. This is the first study to compare VMAT with IMRT for breast cancer. The results show that the RapidArc technique in Eclipse version 11 does not improve all aspects of the treatment plans for the breast cases automatically and easily, but it needs to be manipulated by extra techniques to create acceptable plans thus further research is needed.

  17. A comparative study on the risk of second primary cancers in out-of-field organs associated with radiotherapy of localized prostate carcinoma using Monte Carlo-based accelerator and patient models

    PubMed Central

    Bednarz, Bryan; Athar, Basit; Xu, X. George

    2010-01-01

    Purpose: A physician’s decision regarding an ideal treatment approach (i.e., radiation, surgery, and∕or hormonal) for prostate carcinoma is traditionally based on a variety of metrics. One of these metrics is the risk of radiation-induced second primary cancer following radiation treatments. The aim of this study was to investigate the significance of second cancer risks in out-of-field organs from 3D-CRT and IMRT treatments of prostate carcinoma compared to baseline cancer risks in these organs. Methods: Monte Carlo simulations were performed using a detailed medical linear accelerator model and an anatomically realistic adult male whole-body phantom. A four-field box treatment, a four-field box treatment plus a six-field boost, and a seven-field IMRT treatment were simulated. Using BEIR VII risk models, the age-dependent lifetime attributable risks to various organs outside the primary beam with a known predilection for cancer were calculated using organ-averaged equivalent doses. Results: The four-field box treatment had the lowest treatment-related second primary cancer risks to organs outside the primary beam ranging from 7.3×10−9 to 2.54×10−5%∕MU depending on the patients age at exposure and second primary cancer site. The risks to organs outside the primary beam from the four-field box and six-field boost and the seven-field IMRT were nearly equivalent. The risks from the four-field box and six-field boost ranged from 1.39×10−8 to 1.80×10−5%∕MU, and from the seven-field IMRT ranged from 1.60×10−9 to 1.35×10−5%∕MU. The second cancer risks in all organs considered from each plan were below the baseline risks. Conclusions: The treatment-related second cancer risks in organs outside the primary beam due to 3D-CRT and IMRT is small. New risk assessment techniques need to be investigated to address the concern of radiation-induced second cancers from prostate treatments, particularly focusing on risks to organs inside the primary beam

  18. SU-E-T-60: A Plan Quality Index in IMRT QA That Is Independent of the Acceptance Criteria

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kim, D; Kang, S; Kim, T

    2015-06-15

    Purpose: In IMRT QA, plan quality evaluation is made based on pass rate under preset acceptance criteria, mostly using gamma-values. This method is convenient but, its Result highly depends on what the acceptance criteria are and suffers from the lack of sensitivity in judging how good the plan is. In this study, we introduced a simple but effective plan quality index of IMRT QA based on dose difference only to supplement such shortcomings, and investigated its validity. Methods: The proposed index is a single value which is calculated mainly based on point-by-point comparison between planned and measured dose distributions, andmore » it becomes “1” in an ideal case. A systematic evaluation was performed with one-dimensional test dose distributions. For 3 hypothetical dose profiles, various displacements (in both dose and space) were introduced, the proposed index was calculated for each case, and the behavior of obtained indices was analyzed and compared with that of gamma evaluation. In addition, the feasibility of the index was assessed with clinical IMRT/VMAT/SBRT QA cases for different sites (prostate, head & neck, liver, lung, spine, and abdomen). Results: The proposed index showed more robust correlation with the amount of induced displacement compared to the gamma evaluation method. No matter what the acceptance criteria are (e.g., whether 3%/3mm or 2%/2mm), it was possible to clearly rank every case with the proposed index while it was difficult to do with the gamma evaluation method. Conclusion: IMRT plan quality can be evaluated quantitatively by the proposed index. It is considered that the proposed index would provide useful information for better judging the level of goodness of each plan and its Result is independent of the acceptance criteria. This work was supported by the Radiation Technology R&D program (No. 2013M2A2A7043498) and the Mid-career Researcher Program (2014R1A2A1A10050270) through the National Research Foundation of Korea funded

  19. Inflammatory breast cancer: enhanced local control with hyperfractionated radiotherapy and infusional vincristine, ifosfamide and epirubicin.

    PubMed

    Gurney, H; Harnett, P; Kefford, R; Boyages, J

    1998-06-01

    Local control rate for inflammatory breast cancer (IBC) is < 50% with standard chemotherapy-radiotherapy regimen. Nineteen women (age range 40-65, median 50 years) with IBC (18 patients) or with a primary tumour of > 10 cm (one patient) received a novel treatment comprising hyperfractionated radiotherapy (HFRT) sandwiched between two cycles of infusional chemotherapy using vincristine, ifosfamide and epirubicin (VIE). The primary endpoint was local control. VIE was continuously infused for six weeks via a Hickman's line using a Deltec CADD-1 ambulatory pump. Ifosfamide (3 gm/m2) mixed with equi-dose mesna was infused for seven days and alternated every week with an infusion of epirubicin (50 mg/m2) mixed with vincristine (1.5 mg/m2). HFRT consisted of 1.5 Gy twice daily for 34 frct (51 Gy) followed by a boost of 15 Gy in 10 frct. The total treatment time was less than 22 weeks. Median follow-up was 37 months. Local control rate was 58%. Three patients failed to respond initially and five relapsed in the breast at a median time of 36.8 months. Median overall and disease-free survival was 18 and 25.3 months respectively. Toxicity from VIE was minimal (WHO gd 3 emesis--two patients, gd 3 mucositis--one patient, neutropenic sepsis--three patients). Radiotherapy caused moist desquamation in 17/19 patients. Twenty-four central lines were complicated by seven line infections, three thromboses, and one extravasation. The local control rate of 58% with VIE + HFRT appears similar to reported chemoradiotherapy regimen, although the treatment time of 22 weeks is much shorter than other regimens which take up to 12 months. Toxicity is acceptable. Hickman-related complications need to be reduced. The study is ongoing.

  20. Lowering whole-body radiation doses in pediatric intensity-modulated radiotherapy through the use of unflattened photon beams.

    PubMed

    Cashmore, Jason; Ramtohul, Mark; Ford, Dan

    2011-07-15

    Intensity modulated radiotherapy (IMRT) has been linked with an increased risk of secondary cancer induction due to the extra leakage radiation associated with delivery of these techniques. Removal of the flattening filter offers a simple way of reducing head leakage, and it may be possible to generate equivalent IMRT plans and to deliver these on a standard linear accelerator operating in unflattened mode. An Elekta Precise linear accelerator has been commissioned to operate in both conventional and unflattened modes (energy matched at 6 MV) and a direct comparison made between the treatment planning and delivery of pediatric intracranial treatments using both approaches. These plans have been evaluated and delivered to an anthropomorphic phantom. Plans generated in unflattened mode are clinically identical to those for conventional IMRT but can be delivered with greatly reduced leakage radiation. Measurements in an anthropomorphic phantom at clinically relevant positions including the thyroid, lung, ovaries, and testes show an average reduction in peripheral doses of 23.7%, 29.9%, 64.9%, and 70.0%, respectively, for identical plan delivery compared to conventional IMRT. IMRT delivery in unflattened mode removes an unwanted and unnecessary source of scatter from the treatment head and lowers leakage doses by up to 70%, thereby reducing the risk of radiation-induced second cancers. Removal of the flattening filter is recommended for IMRT treatments. Copyright © 2011 Elsevier Inc. All rights reserved.

  1. Fraction-variant beam orientation optimization for non-coplanar IMRT

    NASA Astrophysics Data System (ADS)

    O'Connor, Daniel; Yu, Victoria; Nguyen, Dan; Ruan, Dan; Sheng, Ke

    2018-02-01

    Conventional beam orientation optimization (BOO) algorithms for IMRT assume that the same set of beam angles is used for all treatment fractions. In this paper we present a BOO formulation based on group sparsity that simultaneously optimizes non-coplanar beam angles for all fractions, yielding a fraction-variant (FV) treatment plan. Beam angles are selected by solving a multi-fraction fluence map optimization problem involving 500-700 candidate beams per fraction, with an additional group sparsity term that encourages most candidate beams to be inactive. The optimization problem is solved using the fast iterative shrinkage-thresholding algorithm. Our FV BOO algorithm is used to create five-fraction treatment plans for digital phantom, prostate, and lung cases as well as a 30-fraction plan for a head and neck case. A homogeneous PTV dose coverage is maintained in all fractions. The treatment plans are compared with fraction-invariant plans that use a fixed set of beam angles for all fractions. The FV plans reduced OAR mean dose and D 2 values on average by 3.3% and 3.8% of the prescription dose, respectively. Notably, mean OAR dose was reduced by 14.3% of prescription dose (rectum), 11.6% (penile bulb), 10.7% (seminal vesicle), 5.5% (right femur), 3.5% (bladder), 4.0% (normal left lung), 15.5% (cochleas), and 5.2% (chiasm). D 2 was reduced by 14.9% of prescription dose (right femur), 8.2% (penile bulb), 12.7% (proximal bronchus), 4.1% (normal left lung), 15.2% (cochleas), 10.1% (orbits), 9.1% (chiasm), 8.7% (brainstem), and 7.1% (parotids). Meanwhile, PTV homogeneity defined as D 95/D 5 improved from .92 to .95 (digital phantom), from .95 to .98 (prostate case), and from .94 to .97 (lung case), and remained constant for the head and neck case. Moreover, the FV plans are dosimetrically similar to conventional plans that use twice as many beams per fraction. Thus, FV BOO offers the potential to reduce delivery time for non-coplanar IMRT.

  2. COMPARISON OF THE PERIPHERAL DOSES FROM DIFFERENT IMRT TECHNIQUES FOR PEDIATRIC HEAD AND NECK RADIATION THERAPY.

    PubMed

    Toyota, Masahiko; Saigo, Yasumasa; Higuchi, Kenta; Fujimura, Takuya; Koriyama, Chihaya; Yoshiura, Takashi; Akiba, Suminori

    2017-11-01

    Intensity-modulated radiation therapy (IMRT) can deliver high and homogeneous doses to the target area while limiting doses to organs at risk. We used a pediatric phantom to simulate the treatment of a head and neck tumor in a child. The peripheral doses were examined for three different IMRT techniques [dynamic multileaf collimator (DMLC), segmental multileaf collimator (SMLC) and volumetric modulated arc therapy (VMAT)]. Peripheral doses were evaluated taking thyroid, breast, ovary and testis as the points of interest. Doses were determined using a radio-photoluminescence glass dosemeter, and the COMPASS system was used for three-dimensional dose evaluation. VMAT achieved the lowest peripheral doses because it had the highest monitor unit efficiency. However, doses in the vicinity of the irradiated field, i.e. the thyroid, could be relatively high, depending on the VMAT collimator angle. DMLC and SMLC had a large area of relatively high peripheral doses in the breast region. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  3. An external dosimetry audit programme to credential static and rotational IMRT delivery for clinical trials quality assurance.

    PubMed

    Eaton, David J; Tyler, Justine; Backshall, Alex; Bernstein, David; Carver, Antony; Gasnier, Anne; Henderson, Julia; Lee, Jonathan; Patel, Rushil; Tsang, Yatman; Yang, Huiqi; Zotova, Rada; Wells, Emma

    2017-03-01

    External dosimetry audits give confidence in the safe and accurate delivery of radiotherapy. The RTTQA group have performed an on-site audit programme for trial recruiting centres, who have recently implemented static or rotational IMRT, and those with major changes to planning or delivery systems. Measurements of reference beam output were performed by the host centre, and by the auditor using independent equipment. Verification of clinical plans was performed using the ArcCheck helical diode array. A total of 54 measurement sessions were performed between May 2014 and June 2016 at 28 UK institutions, reflecting the different combinations of planning and delivery systems used at each institution. Average ratio of measured output between auditor and host was 1.002±0.006. Average point dose agreement for clinical plans was -0.3±1.8%. Average (and 95% lower confidence intervals) of gamma pass rates at 2%/2mm, 3%/2mm and 3%/3mm respectively were: 92% (80%), 96% (90%) and 98% (94%). Moderately significant differences were seen between fixed gantry angle and rotational IMRT, and between combination of planning systems and linac manufacturer, but not between anatomical treatment site or beam energy. An external audit programme has been implemented for universal and efficient credentialing of IMRT treatments in clinical trials. Good agreement was found between measured and expected doses, with few outliers, leading to a simple table of optimal and mandatory tolerances for approval of dosimetry audit results. Feedback was given to some centres leading to improved clinical practice. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  4. Study of the IMRT interplay effect using a 4DCT Monte Carlo dose calculation.

    PubMed

    Jensen, Michael D; Abdellatif, Ady; Chen, Jeff; Wong, Eugene

    2012-04-21

    Respiratory motion may lead to dose errors when treating thoracic and abdominal tumours with radiotherapy. The interplay between complex multileaf collimator patterns and patient respiratory motion could result in unintuitive dose changes. We have developed a treatment reconstruction simulation computer code that accounts for interplay effects by combining multileaf collimator controller log files, respiratory trace log files, 4DCT images and a Monte Carlo dose calculator. Two three-dimensional (3D) IMRT step-and-shoot plans, a concave target and integrated boost were delivered to a 1D rigid motion phantom. Three sets of experiments were performed with 100%, 50% and 25% duty cycle gating. The log files were collected, and five simulation types were performed on each data set: continuous isocentre shift, discrete isocentre shift, 4DCT, 4DCT delivery average and 4DCT plan average. Analysis was performed using 3D gamma analysis with passing criteria of 2%, 2 mm. The simulation framework was able to demonstrate that a single fraction of the integrated boost plan was more sensitive to interplay effects than the concave target. Gating was shown to reduce the interplay effects. We have developed a 4DCT Monte Carlo simulation method that accounts for IMRT interplay effects with respiratory motion by utilizing delivery log files.

  5. SU-F-T-416: Dosimetric Comparison of Coplanar and Non-Coplanar IMRT Plans for Peripheral Lung Lesion

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kang, J; Zhang, S; Philbrook, S

    2016-06-15

    Purpose: The purpose of this study was to compare dosimetric parameters of treatment plans between coplanar and non-coplanar techniques for treating peripheral lung lesions. Methods: The planning CT scans of 6 patients in supine positions were used in this study. The size of the PTV ranges from 163 c.c. to 782 c.c.. The locations of PTV are mostly at the peripheral of Lung, some spreading to the mediastinum. For each patient, we generated two IMRT plans, one with and the other without non-coplanar beams. The non-coplanar beams were carefully selected so that the beams would never exit patient bodies throughmore » the contralateral lung. The IMRT plans were generated with Pinnacle 9.8 treatment planning software. The IMRT optimization objectives were kept the same for the corresponding pairs of plans. All plans were normalized such that 95% of PTV receives the prescription dose (full dose). Results: The conformity index (mean±standard deviation of the mean) is 1.49±0.14 and 1.58±0.23 for the coplanar and noncoplanar plans, respectively. The heterogeneity index (mean±standard deviation of the mean) is 7.74 ±2.33 and 6.34±1.40 for the coplanar and non-coplanar plans, respectively. The maximum heart dose is 60.94±6.22 and 60.42±7.21 Gy, and mean heart dose is 10.22 ±7.57, 9.07 ±6.32 Gy, for the coplanar and non-coplanar plans, respectively. The ipsilateral lung V20 is 48.0%±2.4% and 47.5%±3.3%, and V5 is 68.2%±10.0% and 69.1%±7.3%, for the coplanar and noncoplanar plans, respectively. Furthermore, with the non-coplanar beam arrangement, the contralateral lung V20 was reduced from 3.3%±3.7% to 1.3%±0.8%, and the contralateral Lung V5 is reduced significantly from 65.6%±9.3% to 33.5%±20.9% (p value =0.008). Conclusion: The IMRT plans with non-coplanar beam arrangement could reduce the exit dose to the contralateral lung, and therefore reduce the contralateral lung V5 significantly. This method is especially helpful while the lung lesion doesn’t have

  6. SU-F-J-13: Choosing An IMRT Technique in the Treatment of Head and Neck Cancer with Daily Localization Uncertainties

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Lin, T; Wang, L; Galloway, T

    Purpose: Head and Neck cancer treatment with IMRT/VMAT has two choices: split-filed IMRT(SFI), in which the LAN is treated with a separate anterior field and the extended whole-field IMRT(WFI) in which LAN is included with the IMRT/VMAT field. This study shows that under the same dose limit criteria, choosing the technique becomes a critical issue if daily localization and immobilization altered the dose distribution. Methods: Nine common head-and-neck cancer cases were chosen to illustrate how the daily localization and immobilization uncertainties affect to choose between SFI and WFI. Both SFI and WFI at upper target coverage were generated with VMAT.more » For each case, the same planning criteria were applied to the target and critical structures; therefore, similar target coverage and dose falloff can be observed in both techniques. Thirty days of kV cone beam CT(CBCT) images on each case were also delineated with contralateral and ipsilateral target as well as larynx as critical structure. About 300 CBCT images with daily delivered doses were analyzed and compared in a form of dose-volume histograms. Results: While both plans for SFI and WFI with VMAT planning utilized and meet the criteria of D95>prescription dose and for not-involved larynx with mean dose <35Gy and V55<10%, the daily localization and immobilization has a great contribution to the resulted dose delivery. With WFI, the better daily contralateral and ipsilateral neck target coverage can reflect a simpler or shorter localization; however, a much superior avoidance (WFI: mean dose a 42.5Gy; SFI: mean dose a 18.9Gy) of the non-involved larynx from the SFI is preferred. Conclusion: Dosimetrically, SFI and WFI are equally well for head and Neck cancer treatment with VMAT technique; however, if considering the contribution of daily localization(CBCT) method uncertainties, SFI is better with sparing non-involved larynx and WFI has better target coverage.« less

  7. Trajectory Modulated Arc Therapy: A Fully Dynamic Delivery With Synchronized Couch and Gantry Motion Significantly Improves Dosimetric Indices Correlated With Poor Cosmesis in Accelerated Partial Breast Irradiation

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Liang, Jieming; Atwood, Todd; Eyben, Rie von

    2015-08-01

    Purpose: To develop planning and delivery capabilities for linear accelerator–based nonisocentric trajectory modulated arc therapy (TMAT) and to evaluate the benefit of TMAT for accelerated partial breast irradiation (APBI) with the patient in prone position. Methods and Materials: An optimization algorithm for volumetrically modulated arc therapy (VMAT) was generalized to allow for user-defined nonisocentric TMAT trajectories combining couch rotations and translations. After optimization, XML scripts were automatically generated to program and subsequently deliver the TMAT plans. For 10 breast patients in the prone position, TMAT and 6-field noncoplanar intensity modulated radiation therapy (IMRT) plans were generated under equivalent objectives andmore » constraints. These plans were compared with regard to whole breast tissue volume receiving more than 100%, 80%, 50%, and 20% of the prescription dose. Results: For TMAT APBI, nonisocentric collision-free horizontal arcs with large angular span (251.5 ± 7.9°) were optimized and delivered with delivery time of ∼4.5 minutes. Percentage changes of whole breast tissue volume receiving more than 100%, 80%, 50%, and 20% of the prescription dose for TMAT relative to IMRT were −10.81% ± 6.91%, −27.81% ± 7.39%, −14.82% ± 9.67%, and 39.40% ± 10.53% (P≤.01). Conclusions: This is a first demonstration of end-to-end planning and delivery implementation of a fully dynamic APBI TMAT. Compared with IMRT, TMAT resulted in marked reduction of the breast tissue volume irradiated at high doses.« less

  8. SU-F-T-227: A Comprehensive Patient Specific, Structure Specific, Pre-Treatment 3D QA Protocol for IMRT, SBRT and VMAT - Clinical Experience

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Gueorguiev, G; Cotter, C; Young, M

    2016-06-15

    Purpose: To present a 3D QA method and clinical results for 550 patients. Methods: Five hundred and fifty patient treatment deliveries (400 IMRT, 75 SBRT and 75 VMAT) from various treatment sites, planned on Raystation treatment planning system (TPS), were measured on three beam-matched Elekta linear accelerators using IBA’s COMPASS system. The difference between TPS computed and delivered dose was evaluated in 3D by applying three statistical parameters to each structure of interest: absolute average dose difference (AADD, 6% allowed difference), absolute dose difference greater than 6% (ADD6, 4% structure volume allowed to fail) and 3D gamma test (3%/3mm DTA,more » 4% structure volume allowed to fail). If the allowed value was not met for a given structure, manual review was performed. The review consisted of overlaying dose difference or gamma results with the patient CT, scrolling through the slices. For QA to pass, areas of high dose difference or gamma must be small and not on consecutive slices. For AADD to manually pass QA, the average dose difference in cGy must be less than 50cGy. The QA protocol also includes DVH analysis based on QUANTEC and TG-101 recommended dose constraints. Results: Figures 1–3 show the results for the three parameters per treatment modality. Manual review was performed on 67 deliveries (27 IMRT, 22 SBRT and 18 VMAT), for which all passed QA. Results show that statistical parameter AADD may be overly sensitive for structures receiving low dose, especially for the SBRT deliveries (Fig.1). The TPS computed and measured DVH values were in excellent agreement and with minimum difference. Conclusion: Applying DVH analysis and different statistical parameters to any structure of interest, as part of the 3D QA protocol, provides a comprehensive treatment plan evaluation. Author G. Gueorguiev discloses receiving travel and research funding from IBA for unrelated to this project work. Author B. Crawford discloses receiving travel

  9. SU-E-T-309: Dosimetric Comparison of Simultaneous Integrated Boost Treatment Plan Between Intensity Modulated Radiotherapies (IMRTs), Dual Arc Volumetric Modulated Arc Therapy (DA-VMAT) and Single Arc Volumetric Modulated Arc Therapy (SA-VMAT) for Nasopharyngeal Carcinoma (NPC)

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sivakumar, R; Janardhan, N; Bhavani, P

    Purpose: To compare the plan quality and performance of Simultaneous Integrated Boost (SIB) Treatment plan between Seven field (7F) and Nine field(9F) Intensity Modulated Radiotherapies and Single Arc (SA) and Dual Arc (DA) Volumetric Modulated Arc Therapy( VMAT). Methods: Retrospective planning study of 16 patients treated in Elekta Synergy Platform (mlci2) by 9F-IMRT were replanned with 7F-IMRT, Single Arc VMAT and Dual Arc VMAT using CMS, Monaco Treatment Planning System (TPS) with Monte Carlo simulation. Target delineation done as per Radiation Therapy Oncology Protocols (RTOG 0225&0615). Dose Prescribed as 70Gy to Planning Target Volumes (PTV70) and 61Gy to PTV61 inmore » 33 fraction as a SIB technique. Conformity Index(CI), Homogeneity Index(HI) were used as analysis parameter for Target Volumes as well as Mean dose and Max dose for Organ at Risk(OAR,s).Treatment Delivery Time(min), Monitor unit per fraction (MU/fraction), Patient specific quality assurance were also analysed. Results: A Poor dose coverage and Conformity index (CI) was observed in PTV70 by 7F-IMRT among other techniques. SA-VMAT achieved poor dose coverage in PTV61. No statistical significance difference observed in OAR,s except Spinal cord (P= 0.03) and Right optic nerve (P=0.03). DA-VMAT achieved superior target coverage, higher CI (P =0.02) and Better HI (P=0.03) for PTV70 other techniques (7F-IMRT/9F-IMRT/SA-VMAT). A better dose spare for Parotid glands and spinal cord were seen in DA-VMAT. The average treatment delivery time were 5.82mins, 6.72mins, 3.24mins, 4.3mins for 7F-IMRT, 9F-IMRT, SA-VMAT and DA-VMAT respectively. Significance difference Observed in MU/fr (P <0.001) and Patient quality assurance pass rate were >95% (Gamma analysis (Γ3mm, 3%). Conclusion: DA-VAMT showed better target dose coverage and achieved better or equal performance in sparing OARs among other techniques. SA-VMAT offered least Treatment Time than other techniques but achieved poor target coverage. DA

  10. On the use of biomathematical models in patient-specific IMRT dose QA

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zhen Heming; Nelms, Benjamin E.; Tome, Wolfgang A.

    2013-07-15

    Purpose: To investigate the use of biomathematical models such as tumor control probability (TCP) and normal tissue complication probability (NTCP) as new quality assurance (QA) metrics.Methods: Five different types of error (MLC transmission, MLC penumbra, MLC tongue and groove, machine output, and MLC position) were intentionally induced to 40 clinical intensity modulated radiation therapy (IMRT) patient plans (20 H and N cases and 20 prostate cases) to simulate both treatment planning system errors and machine delivery errors in the IMRT QA process. The changes in TCP and NTCP for eight different anatomic structures (H and N: CTV, GTV, both parotids,more » spinal cord, larynx; prostate: CTV, rectal wall) were calculated as the new QA metrics to quantify the clinical impact on patients. The correlation between the change in TCP/NTCP and the change in selected DVH values was also evaluated. The relation between TCP/NTCP change and the characteristics of the TCP/NTCP curves is discussed.Results:{Delta}TCP and {Delta}NTCP were summarized for each type of induced error and each structure. The changes/degradations in TCP and NTCP caused by the errors vary widely depending on dose patterns unique to each plan, and are good indicators of each plan's 'robustness' to that type of error.Conclusions: In this in silico QA study the authors have demonstrated the possibility of using biomathematical models not only as patient-specific QA metrics but also as objective indicators that quantify, pretreatment, a plan's robustness with respect to possible error types.« less

  11. Homogeneous and inhomogeneous material effect in gamma index evaluation of IMRT technique based on fan beam and Cone Beam CT patient images

    NASA Astrophysics Data System (ADS)

    Wibowo, W. E.; Waliyyulhaq, M.; Pawiro, S. A.

    2017-05-01

    Patient-specific Quality Assurance (QA) technique in lung case Intensity-Modulated Radiation Therapy (IMRT) is traditionally limited to homogeneous material, although the fact that the planning is carried out with inhomogeneous material present. Moreover, the chest area has many of inhomogeneous material, such as lung, soft tissue, and bone, which inhomogeneous material requires special attention to avoid inaccuracies in dose calculation in the Treatment Planning System (TPS). Recent preliminary studies shown that the role of Cone Beam CT (CBCT) can be used not only to position the patient at the time prior to irradiation but also to serve as planning modality. Our study presented the influence of a homogeneous and inhomogeneous materials using Fan Beam CT and Cone Beam CT modalities in IMRT technique on the Gamma Index (GI) value. We used a variation of the segment and Calculation Grid Resolution (CGR). The results showed the deviation of averaged GI value to be between CGR 0.2 cm and 0.4 cm with homogeneous material ranging from -0.44% to 1.46%. For inhomogeneous material, the value was range from -1.74% to 0.98%. In performing patient-specific IMRT QA techniques for lung cancer, homogeneous material can be implemented in evaluating the gamma index.

  12. Adequate margins for random setup uncertainties in head-and-neck IMRT

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Astreinidou, Eleftheria; Bel, Arjan; Raaijmakers, Cornelis P.J.

    2005-03-01

    Purpose: To investigate the effect of random setup uncertainties on the highly conformal dose distributions produced by intensity-modulated radiotherapy (IMRT) for clinical head-and-neck cancer patients and to determine adequate margins to account for those uncertainties. Methods and materials: We have implemented in our clinical treatment planning system the possibility of simulating normally distributed patient setup displacements, translations, and rotations. The planning CT data of 8 patients with Stage T1-T3N0M0 oropharyngeal cancer were used. The clinical target volumes of the primary tumor (CTV{sub primary}) and of the lymph nodes (CTV{sub elective}) were expanded by 0.0, 1.5, 3.0, and 5.0 mm inmore » all directions, creating the planning target volumes (PTVs). We performed IMRT dose calculation using our class solution for each PTV margin, resulting in the conventional static plans. Then, the system recalculated the plan for each positioning displacement derived from a normal distribution with {sigma} = 2 mm and {sigma} = 4 mm (standard deviation) for translational deviations and {sigma} = 1 deg for rotational deviations. The dose distributions of the 30 fractions were summed, resulting in the actual plan. The CTV dose coverage of the actual plans was compared with that of the static plans. Results: Random translational deviations of {sigma} = 2 mm and rotational deviations of {sigma} = 1 deg did not affect the CTV{sub primary} volume receiving 95% of the prescribed dose (V{sub 95}) regardless of the PTV margin used. A V{sub 95} reduction of 3% and 1% for a 0.0-mm and 1.5-mm PTV margin, respectively, was observed for {sigma} = 4 mm. The V{sub 95} of the CTV{sub elective} contralateral was approximately 1% and 5% lower than that of the static plan for {sigma} = 2 mm and {sigma} = 4 mm, respectively, and for PTV margins < 5.0 mm. An additional reduction of 1% was observed when rotational deviations were included. The same effect was observed for the CTV

  13. IMRT sequencing for a six-bank multi-leaf system.

    PubMed

    Topolnjak, R; van der Heide, U A; Lagendijk, J J W

    2005-05-07

    In this study, we present a sequencer for delivering step-and-shoot IMRT using a six-bank multi-leaf system. Such a system was proposed earlier and combines a high-resolution field-shaping ability with a large field size. It consists of three layers of two opposing leaf banks with 1 cm leaves. The layers are rotated relative to each other at 60 degrees . A low-resolution mode of sequencing is achieved by using one layer of leaves as primary MLC, while the other two are used to improve back-up collimation. For high-resolution sequencing, an algorithm is presented that creates segments shaped by all six banks. Compared to a hypothetical mini-MLC with 0.4 cm leaves, a similar performance can be achieved, but a trade-off has to be made between accuracy and the number of segments.

  14. A Phase I Dose Escalation Study of Hypofractionated IMRT Field-in-Field Boost for Newly Diagnosed Glioblastoma Multiforme

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Monjazeb, Arta M., E-mail: arta.monjazeb@ucdmc.ucdavis.edu; Ayala, Deandra; Jensen, Courtney

    2012-02-01

    Objectives: To describe the results of a Phase I dose escalation trial for newly diagnosed glioblastoma multiforme (GBM) using a hypofractionated concurrent intensity-modulated radiotherapy (IMRT) boost. Methods: Twenty-one patients were enrolled between April 1999 and August 2003. Radiotherapy consisted of daily fractions of 1.8 Gy with a concurrent boost of 0.7 Gy (total 2.5 Gy daily) to a total dose of 70, 75, or 80 Gy. Concurrent chemotherapy was not permitted. Seven patients were enrolled at each dose and dose limiting toxicities were defined as irreversible Grade 3 or any Grade 4-5 acute neurotoxicity attributable to radiotherapy. Results: All patientsmore » experienced Grade 1 or 2 acute toxicities. Acutely, 8 patients experienced Grade 3 and 1 patient experienced Grade 3 and 4 toxicities. Of these, only two reversible cases of otitis media were attributable to radiotherapy. No dose-limiting toxicities were encountered. Only 2 patients experienced Grade 3 delayed toxicity and there was no delayed Grade 4 toxicity. Eleven patients requiring repeat resection or biopsy were found to have viable tumor and radiation changes with no cases of radionecrosis alone. Median overall and progression-free survival for this cohort were 13.6 and 6.5 months, respectively. One- and 2-year survival rates were 57% and 19%. At recurrence, 15 patients received chemotherapy, 9 underwent resection, and 5 received radiotherapy. Conclusions: Using a hypofractionated concurrent IMRT boost, we were able to safely treat patients to 80 Gy without any dose-limiting toxicity. Given that local failure still remains the predominant pattern for GBM patients, a trial of dose escalation with IMRT and temozolomide is warranted.« less

  15. The effect of statistical noise on IMRT plan quality and convergence for MC-based and MC-correction-based optimized treatment plans.

    PubMed

    Siebers, Jeffrey V

    2008-04-04

    Monte Carlo (MC) is rarely used for IMRT plan optimization outside of research centres due to the extensive computational resources or long computation times required to complete the process. Time can be reduced by degrading the statistical precision of the MC dose calculation used within the optimization loop. However, this eventually introduces optimization convergence errors (OCEs). This study determines the statistical noise levels tolerated during MC-IMRT optimization under the condition that the optimized plan has OCEs <100 cGy (1.5% of the prescription dose) for MC-optimized IMRT treatment plans.Seven-field prostate IMRT treatment plans for 10 prostate patients are used in this study. Pre-optimization is performed for deliverable beams with a pencil-beam (PB) dose algorithm. Further deliverable-based optimization proceeds using: (1) MC-based optimization, where dose is recomputed with MC after each intensity update or (2) a once-corrected (OC) MC-hybrid optimization, where a MC dose computation defines beam-by-beam dose correction matrices that are used during a PB-based optimization. Optimizations are performed with nominal per beam MC statistical precisions of 2, 5, 8, 10, 15, and 20%. Following optimizer convergence, beams are re-computed with MC using 2% per beam nominal statistical precision and the 2 PTV and 10 OAR dose indices used in the optimization objective function are tallied. For both the MC-optimization and OC-optimization methods, statistical equivalence tests found that OCEs are less than 1.5% of the prescription dose for plans optimized with nominal statistical uncertainties of up to 10% per beam. The achieved statistical uncertainty in the patient for the 10% per beam simulations from the combination of the 7 beams is ~3% with respect to maximum dose for voxels with D>0.5D(max). The MC dose computation time for the OC-optimization is only 6.2 minutes on a single 3 Ghz processor with results clinically equivalent to high precision MC

  16. A retrospective planning analysis comparing intensity modulated radiation therapy (IMRT) to volumetric modulated arc therapy (VMAT) using two optimization algorithms for the treatment of early-stage prostate cancer

    PubMed Central

    Elith, Craig A; Dempsey, Shane E; Warren-Forward, Helen M

    2013-01-01

    Introduction The primary aim of this study is to compare intensity modulated radiation therapy (IMRT) to volumetric modulated arc therapy (VMAT) for the radical treatment of prostate cancer using version 10.0 (v10.0) of Varian Medical Systems, RapidArc radiation oncology system. Particular focus was placed on plan quality and the implications on departmental resources. The secondary objective was to compare the results in v10.0 to the preceding version 8.6 (v8.6). Methods Twenty prostate cancer cases were retrospectively planned using v10.0 of Varian's Eclipse and RapidArc software. Three planning techniques were performed: a 5-field IMRT, VMAT using one arc (VMAT-1A), and VMAT with two arcs (VMAT-2A). Plan quality was assessed by examining homogeneity, conformity, the number of monitor units (MUs) utilized, and dose to the organs at risk (OAR). Resource implications were assessed by examining planning and treatment times. The results obtained using v10.0 were also compared to those previously reported by our group for v8.6. Results In v10.0, each technique was able to produce a dose distribution that achieved the departmental planning guidelines. The IMRT plans were produced faster than VMAT plans and displayed improved homogeneity. The VMAT plans provided better conformity to the target volume, improved dose to the OAR, and required fewer MUs. Treatments using VMAT-1A were significantly faster than both IMRT and VMAT-2A. Comparison between versions 8.6 and 10.0 revealed that in the newer version, VMAT planning was significantly faster and the quality of the VMAT dose distributions produced were of a better quality. Conclusion VMAT (v10.0) using one or two arcs provides an acceptable alternative to IMRT for the treatment of prostate cancer. VMAT-1A has the greatest impact on reducing treatment time. PMID:26229615

  17. Lowering Whole-Body Radiation Doses in Pediatric Intensity-Modulated Radiotherapy Through the Use of Unflattened Photon Beams;Flattening filter; Pediatric; Intensity-modulated radiotherapy; Second cancers; Radiation-induced malignancies

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Cashmore, Jason, E-mail: Jason.cashmore@uhb.nhs.uk; Ramtohul, Mark; Ford, Dan

    Purpose: Intensity modulated radiotherapy (IMRT) has been linked with an increased risk of secondary cancer induction due to the extra leakage radiation associated with delivery of these techniques. Removal of the flattening filter offers a simple way of reducing head leakage, and it may be possible to generate equivalent IMRT plans and to deliver these on a standard linear accelerator operating in unflattened mode. Methods and Materials: An Elekta Precise linear accelerator has been commissioned to operate in both conventional and unflattened modes (energy matched at 6 MV) and a direct comparison made between the treatment planning and delivery ofmore » pediatric intracranial treatments using both approaches. These plans have been evaluated and delivered to an anthropomorphic phantom. Results: Plans generated in unflattened mode are clinically identical to those for conventional IMRT but can be delivered with greatly reduced leakage radiation. Measurements in an anthropomorphic phantom at clinically relevant positions including the thyroid, lung, ovaries, and testes show an average reduction in peripheral doses of 23.7%, 29.9%, 64.9%, and 70.0%, respectively, for identical plan delivery compared to conventional IMRT. Conclusions: IMRT delivery in unflattened mode removes an unwanted and unnecessary source of scatter from the treatment head and lowers leakage doses by up to 70%, thereby reducing the risk of radiation-induced second cancers. Removal of the flattening filter is recommended for IMRT treatments.« less

  18. Dosimetric evaluation of a Monte Carlo IMRT treatment planning system incorporating the MIMiC

    NASA Astrophysics Data System (ADS)

    Rassiah-Szegedi, P.; Fuss, M.; Sheikh-Bagheri, D.; Szegedi, M.; Stathakis, S.; Lancaster, J.; Papanikolaou, N.; Salter, B.

    2007-12-01

    The high dose per fraction delivered to lung lesions in stereotactic body radiation therapy (SBRT) demands high dose calculation and delivery accuracy. The inhomogeneous density in the thoracic region along with the small fields used typically in intensity-modulated radiation therapy (IMRT) treatments poses a challenge in the accuracy of dose calculation. In this study we dosimetrically evaluated a pre-release version of a Monte Carlo planning system (PEREGRINE 1.6b, NOMOS Corp., Cranberry Township, PA), which incorporates the modeling of serial tomotherapy IMRT treatments with the binary multileaf intensity modulating collimator (MIMiC). The aim of this study is to show the validation process of PEREGRINE 1.6b since it was used as a benchmark to investigate the accuracy of doses calculated by a finite size pencil beam (FSPB) algorithm for lung lesions treated on the SBRT dose regime via serial tomotherapy in our previous study. Doses calculated by PEREGRINE were compared against measurements in homogeneous and inhomogeneous materials carried out on a Varian 600C with a 6 MV photon beam. Phantom studies simulating various sized lesions were also carried out to explain some of the large dose discrepancies seen in the dose calculations with small lesions. Doses calculated by PEREGRINE agreed to within 2% in water and up to 3% for measurements in an inhomogeneous phantom containing lung, bone and unit density tissue.

  19. A fiducial detection algorithm for real-time image guided IMRT based on simultaneous MV and kV imaging

    PubMed Central

    Mao, Weihua; Riaz, Nadeem; Lee, Louis; Wiersma, Rodney; Xing, Lei

    2008-01-01

    The advantage of highly conformal dose techniques such as 3DCRT and IMRT is limited by intrafraction organ motion. A new approach to gain near real-time 3D positions of internally implanted fiducial markers is to analyze simultaneous onboard kV beam and treatment MV beam images (from fluoroscopic or electronic portal image devices). Before we can use this real-time image guidance for clinical 3DCRT and IMRT treatments, four outstanding issues need to be addressed. (1) How will fiducial motion blur the image and hinder tracking fiducials? kV and MV images are acquired while the tumor is moving at various speeds. We find that a fiducial can be successfully detected at a maximum linear speed of 1.6 cm∕s. (2) How does MV beam scattering affect kV imaging? We investigate this by varying MV field size and kV source to imager distance, and find that common treatment MV beams do not hinder fiducial detection in simultaneous kV images. (3) How can one detect fiducials on images from 3DCRT and IMRT treatment beams when the MV fields are modified by a multileaf collimator (MLC)? The presented analysis is capable of segmenting a MV field from the blocking MLC and detecting visible fiducials. This enables the calculation of nearly real-time 3D positions of markers during a real treatment. (4) Is the analysis fast enough to track fiducials in nearly real time? Multiple methods are adopted to predict marker positions and reduce search regions. The average detection time per frame for three markers in a 1024×768 image was reduced to 0.1 s or less. Solving these four issues paves the way to tracking moving fiducial markers throughout a 3DCRT or IMRT treatment. Altogether, these four studies demonstrate that our algorithm can track fiducials in real time, on degraded kV images (MV scatter), in rapidly moving tumors (fiducial blurring), and even provide useful information in the case when some fiducials are blocked from view by the MLC. This technique can provide a gating signal

  20. Swallowing outcomes following Intensity Modulated Radiation Therapy (IMRT) for head & neck cancer - a systematic review.

    PubMed

    Roe, Justin W G; Carding, Paul N; Dwivedi, Raghav C; Kazi, Rehan A; Rhys-Evans, Peter H; Harrington, Kevin J; Nutting, Christopher M

    2010-10-01

    A systematic review to establish what evidence is available for swallowing outcomes following IMRT for head and neck cancer. Online electronic databases were searched to identify papers published in English from January 1998 to December 2009. Papers were independently appraised by two reviewers for methodological quality, method of swallowing evaluation and categorized according to the World Health Organisation's International Classification of Health Functions. The impact of radiation dose to dysphagia aspiration risk structures (DARS) was also evaluated. Sixteen papers met the inclusion criteria. The literature suggests that limiting the radiation dose to certain structures may result in favourable swallowing outcomes. Methodological limitations included variable assessment methods and outcome measures and heterogeneity of patients. There are only limited prospective data, especially where pre-treatment measures have been taken and compared to serial post-treatment assessment. Few studies have investigated the impact of IMRT on swallow function and the impact on everyday life. Initial studies have reported potential benefits but are limited in terms of study design and outcome data. Further well designed, prospective, longitudinal swallowing studies including multidimensional evaluation methods are required to enable a more comprehensive understanding of dysphagia complications and inform pre-treatment counselling and rehabilitation planning. Copyright © 2010 Elsevier Ltd. All rights reserved.

  1. Role of radiotherapy fractionation in head and neck cancers (MARCH): an updated meta-analysis

    PubMed Central

    Lacas, Benjamin; Bourhis, Jean; Overgaard, Jens; Zhang, Qiang; Gregoire, Vincent; Nankivell, Matthew; Zackrisson, Bjorn; Szutkowski, Zbigniew; Suwiński, Rafał; Poulsen, Michael; O’Sullivan, Brian; Corvo, Renzo; Laskar, Sarbani Ghosh; Fallai, Carlo; Yamazaki, Hideya; Dobrowsky, Werner; Cho, Kwan Ho; Garden, Adam S; Langendijk, Johannes A; Viegas, Celia Maria Pais; Hay, John; Lotayef, Mohamed; Parmar, Mahesh K B; Auperin, Anne; van Herpen, Carla; Maingon, Philippe; Trotti, Andy M; Grau, Cai; Pignon, Jean-Pierre; Blanchard, Pierre

    2017-01-01

    Summary Background The Meta-Analysis of Radiotherapy in squamous cell Carcinomas of Head and neck (MARCH) showed that altered fractionation radiotherapy is associated with improved overall and progression-free survival compared with conventional radiotherapy, with hyperfractionated radiotherapy showing the greatest benefit. This update aims to confirm and explain the superiority of hyperfractionated radiotherapy over other altered fractionation radiotherapy regimens and to assess the benefit of altered fractionation within the context of concomitant chemotherapy with the inclusion of new trials. Methods For this updated meta-analysis, we searched bibliography databases, trials registries, and meeting proceedings for published or unpublished randomised trials done between Jan 1, 2009, and July 15, 2015, comparing primary or postoperative conventional fractionation radiotherapy versus altered fractionation radiotherapy (comparison 1) or conventional fractionation radiotherapy plus concomitant chemotherapy versus altered fractionation radiotherapy alone (comparison 2). Eligible trials had to start randomisation on or after Jan 1, 1970, and completed accrual before Dec 31, 2010; had to have been randomised in a way that precluded prior knowledge of treatment assignment; and had to include patients with non-metastatic squamous cell carcinoma of the oral cavity, oropharynx, hypopharynx, or larynx undergoing first-line curative treatment. Trials including a non-conventional radiotherapy control group, investigating hypofractionated radiotherapy, or including mostly nasopharyngeal carcinomas were excluded. Trials were grouped in three types of altered fractionation: hyperfractionated, moderately accelerated, and very accelerated. Individual patient data were collected and combined with a fixed-effects model based on the intention-to-treat principle. The primary endpoint was overall survival. Findings Comparison 1 (conventional fractionation radiotherapy vs altered

  2. SU-E-T-164: Clinical Implementation of ASi EPID Panels for QA of IMRT/VMAT Plans.

    PubMed

    Hosier, K; Wu, C; Beck, K; Radevic, M; Asche, D; Bareng, J; Kroner, A; Lehmann, J; Logsdon, M; Dutton, S; Rosenthal, S

    2012-06-01

    To investigate various issues for clinical implementation of aSi EPID panels for IMRT/VMAT QA. Six linacs are used in our clinic for EPID-based plan QA; two Varian Truebeams, two Varian 2100 series, two Elekta Infiniti series. Multiple corrections must be accounted for in the calibration of each panel for dosimetric use. Varian aSi panels are calibrated with standard dark field, flood field, and 40×40 diagonal profile for beam profile correction. Additional corrections to account for off-axis and support arm backscatter are needed for larger field sizes. Since Elekta iViewGT system does not export gantry angle with images, a third-party inclinometer must be physically mounted to back of linac gantry and synchronized with data acquisition via iViewGT PC clock. A T/2 offset correctly correlates image and gantry angle for arc plans due to iView image time stamp at the end of data acquisition for each image. For both Varian and Elekta panels, a 5 MU 10×10 calibration field is used to account for the nonlinear MU to dose response at higher energies. Acquired EPID images are deconvolved via a high pass filter in Fourier space and resultant fluence maps are used to reconstruct a 3D dose 'delivered' to patient using DosimetryCheck. Results are compared to patient 3D dose computed by TPS using a 3D-gamma analysis. 120 IMRT and 100 VMAT cases are reported. Two 3D gamma quantities (Gamma(V10) and Gamma(PTV)) are proposed for evaluating QA results. The Gamma(PTV) is sensitive to MLC offsets while Gamma(V10) is sensitive to gantry rotations. When a 3mm/3% criteria and 90% or higher 3D gamma pass rate is used, all IMRT and 90% of VMAT QA pass QA. After appropriate calibration of aSi panels and setup of image acquisition systems, EPID based 3D dose reconstruction method is found clinically feasible. © 2012 American Association of Physicists in Medicine.

  3. SU-E-T-583: Operated Left Breast and Chest Wall Radiotherapy: A Dosimetric Comparison Between 3DCRT, IMRT and VMAT

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sarkar, B; Roy, S; Munshi, A

    2015-06-15

    Purpose: To evaluate the comparative dosimetric efficacy between field and field 3DCRT(FnF), multiple field Intensity modulated radiotherapy (SnS IMRT) and, partial arc volumetric modulated arc therapy (VMAT) in case of post operative left side breast and chest wall irradiation. Methods: CT study set of fifteen post-operative left breast and chest wall patient was tested for a treatment plan of 50Gy in 25 fraction using partial arc VMAT, SnSIMRT and tangential beam 3DCRT . 3DCRT FnF gantry angle was ranging for left medial tangential 290±17{sup 0} and Lt lateral tangential l14°±12{sup 0}. For IMRT four fixed beam at gantry angle G130{supmore » 0} G110{sup 0} G300{sup 0} and G330{sup 0} was used, in case of insufficient dose another beam G150{sup 0} was added. In case of partial arc VMAT, lateral tangential arc G130{sup 0}-G100{sup 0} and medial tangential arc G280{sup 0}-G310{sup 0}. Inverse optimization was opted to cover at least 95%PTV by 95% prescription dose (RxD) and a strong weightage on reduction of heart and lung dose. PTV coverage was evaluated for it’s clinically acceptability depending on the tumor spatial location and its quadrant. Out of the three plans, any one was used for the actual patient treatment. Results: Dosimetric analysis done for breast PTV, left lung, heart and the opposite breast. PTV mean dose and maximum dose was 5129.8±214.8cGy, 4749.0±329.7cGy, 5024.6±73.4cGy and 5855.2±510.7cGy, 5340.7±146.1cGy, 5347.2±196.8cGy for FnF, VMAT and IMRT respectively. Ipsilateral lung volume receiving 20Gy and 5Gy was 23.6±9.5cGy and 32.7±10.3cGy for FnF, 18.6±8.7cGy and 38.8±15.2cGy for VMAT and 25.7±9.6cGy and 50.7±8.4cGy for IMRT respectively. Heart mean and 2cc dose was 867.9±456.7cGy and 5038.5±184.3cGy for FnF, 532.6±263cGy and 3632.1±990.6 for VMAT, 711±229.9cGy and 4421±463.7cGy for IMRT respectively. VMAT shows minimum contralateral breast dose 168±113.8cGy. Conclusion: VMAT shows a better tumor conformity, minimum

  4. The risk of radiation-induced second cancers in the high to medium dose region: a comparison between passive and scanned proton therapy, IMRT and VMAT for pediatric patients with brain tumors

    NASA Astrophysics Data System (ADS)

    Moteabbed, Maryam; Yock, Torunn I.; Paganetti, Harald

    2014-06-01

    The incidence of second malignant tumors is a clinically observed adverse late effect of radiation therapy, especially in organs close to the treatment site, receiving medium to high doses (>2.5 Gy). For pediatric patients, choosing the least toxic radiation modality is of utmost importance, due to their high radiosensitivity and small size. This study aims to evaluate the risk of second cancer incidence in the vicinity of the primary radiation field, for pediatric patients with brain/head and neck tumors and compare four treatment modalities: passive scattering and pencil beam scanning proton therapy (PPT and PBS), intensity modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT). For a cohort of six pediatric patients originally treated with PPT, additional PBS, IMRT and VMAT plans were created. Dose distributions from these plans were used to calculate the excess absolute risk (EAR) and lifetime attributable risk (LAR) for developing a second tumor in soft tissue and skull. A widely used risk assessment formalism was employed and compared with a linear model based on recent clinical findings. In general, LAR was found to range between 0.01%-2.8% for PPT/PBS and 0.04%-4.9% for IMRT/VMAT. PBS was associated with the lowest risk for most patients using carcinoma and sarcoma models, whereas IMRT and VMAT risks were comparable and the highest among all modalities. The LAR for IMRT/VMAT relative to PPT ranged from 1.3-4.6 for soft tissue and from 3.5-9.5 for skull. Larger absolute LAR was observed for younger patients and using linear risk models. The number of fields used in proton therapy and IMRT had minimal effect on the risk. When planning treatments and deciding on the treatment modality, the probability of second cancer incidence should be carefully examined and weighed against the possibility of developing acute side effects for each patient individually.

  5. SU-E-T-338: Dosimetric Study of Volumetric Modulated Arc Therapy (VMAT) and Intensity Modulated Radiation Therapy (IMRT) for Stereotactic Body Radiation Therapy (SBRT) in Early Stage Lung Cancer

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ahmad, I; Quinn, K; Seebach, A

    2015-06-15

    Purpose: This study evaluates the dosimetric differences using volumetric modulated arc therapy (VMAT) in patients previously treated with intensity modulated radiation therapy IMRT for stereotactic body radiotherapy (SBRT) in early stage lung cancer. Methods: We evaluated 9 consecutive medically inoperable lung cancer patients at the start of the SBRT program who were treated with IMRT from November 2010 to October 2011. These patients were treated using 6 MV energy. The 9 cases were then re-planned with VMAT performed with arc therapy using 6 MV flattening filter free (FFF) energy with the same organs at risk (OARS) constraints. Data collected formore » the treatment plans included target coverage, beam on time, dose to OARS and gamma pass rate. Results: Five patients were T1N0 and four patients were T2N0 with all tumors less than 5 cm. The average GTV was 13.02 cm3 (0.83–40.87) and average PTV was 44.65 cm3 (14.06–118.08). The IMRT plans had a mean of 7.2 angles (6–9) and 5.4 minutes (3.6–11.1) per plan. The VMAT plans had a mean of 2.8 arcs (2–3) and 4.0 minutes (2.2–6.0) per plan. VMAT had slightly more target coverage than IMRT with average increase in D95 of 2.68% (1.24–5.73) and D99 of 3.65% (0.88–8.77). VMAT produced lower doses to all OARs. The largest reductions were in maximum doses to the spinal cord with an average reduction of 24.1%, esophagus with an average reduction of 22.1%, and lung with an average reduction in the V20 of 16.3% The mean gamma pass rate was 99.8% (99.2–100) at 3 mm and 3% for VMAT with comparable values for IMRT. Conclusion: These findings suggest that using VMAT for SBRT in early stage lung cancer is superior to IMRT in terms of dose coverage, OAR dose and a lower treatment delivery time with a similar gamma pass rate.« less

  6. Feasibility of using Geant4 Monte Carlo simulation for IMRT dose calculations for the Novalis Tx with a HD-120 multi-leaf collimator

    NASA Astrophysics Data System (ADS)

    Jung, Hyunuk; Shin, Jungsuk; Chung, Kwangzoo; Han, Youngyih; Kim, Jinsung; Choi, Doo Ho

    2015-05-01

    The aim of this study was to develop an independent dose verification system by using a Monte Carlo (MC) calculation method for intensity modulated radiation therapy (IMRT) conducted by using a Varian Novalis Tx (Varian Medical Systems, Palo Alto, CA, USA) equipped with a highdefinition multi-leaf collimator (HD-120 MLC). The Geant4 framework was used to implement a dose calculation system that accurately predicted the delivered dose. For this purpose, the Novalis Tx Linac head was modeled according to the specifications acquired from the manufacturer. Subsequently, MC simulations were performed by varying the mean energy, energy spread, and electron spot radius to determine optimum values of irradiation with 6-MV X-ray beams by using the Novalis Tx system. Computed percentage depth dose curves (PDDs) and lateral profiles were compared to the measurements obtained by using an ionization chamber (CC13). To validate the IMRT simulation by using the MC model we developed, we calculated a simple IMRT field and compared the result with the EBT3 film measurements in a water-equivalent solid phantom. Clinical cases, such as prostate cancer treatment plans, were then selected, and MC simulations were performed. The accuracy of the simulation was assessed against the EBT3 film measurements by using a gamma-index criterion. The optimal MC model parameters to specify the beam characteristics were a 6.8-MeV mean energy, a 0.5-MeV energy spread, and a 3-mm electron radius. The accuracy of these parameters was determined by comparison of MC simulations with measurements. The PDDs and the lateral profiles of the MC simulation deviated from the measurements by 1% and 2%, respectively, on average. The computed simple MLC fields agreed with the EBT3 measurements with a 95% passing rate with 3%/3-mm gamma-index criterion. Additionally, in applying our model to clinical IMRT plans, we found that the MC calculations and the EBT3 measurements agreed well with a passing rate of greater

  7. Comparison of 3D CRT and IMRT Tratment Plans

    PubMed Central

    Bakiu, Erjona; Telhaj, Ervis; Kozma, Elvisa; Ruçi, Ferdinand; Malkaj, Partizan

    2013-01-01

    Plans of patients with prostate tumor have been studied. These patients have been scanned in the CT simulator and the images have been sent to the Focal, the system where the doctor delineates the tumor and the organs at risk. After that in the treatment planning system XiO there are created for the same patients three dimensional conformal and intensity modulated radiotherapy treatment plans. The planes are compared according to the dose volume histograms. It is observed that the plans with IMRT technique conform better the isodoses to the planning target volume and protect more the organs at risk, but the time needed to create such plans and to control it is higher than 3D CRT. So it necessary to decide in which patients to do one or the other technique depending on the full dose given to PTV and time consuming in genereral. PMID:24167395

  8. SU-E-T-500: Initial Implementation of GPU-Based Particle Swarm Optimization for 4D IMRT Planning in Lung SBRT

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Modiri, A; Hagan, A; Gu, X

    Purpose 4D-IMRT planning, combined with dynamic MLC tracking delivery, utilizes the temporal dimension as an additional degree of freedom to achieve improved OAR-sparing. The computational complexity for such optimization increases exponentially with increase in dimensionality. In order to accomplish this task in a clinically-feasible time frame, we present an initial implementation of GPU-based 4D-IMRT planning based on particle swarm optimization (PSO). Methods The target and normal structures were manually contoured on ten phases of a 4DCT scan of a NSCLC patient with a 54cm3 right-lower-lobe tumor (1.5cm motion). Corresponding ten 3D-IMRT plans were created in the Eclipse treatment planning systemmore » (Ver-13.6). A vendor-provided scripting interface was used to export 3D-dose matrices corresponding to each control point (10 phases × 9 beams × 166 control points = 14,940), which served as input to PSO. The optimization task was to iteratively adjust the weights of each control point and scale the corresponding dose matrices. In order to handle the large amount of data in GPU memory, dose matrices were sparsified and placed in contiguous memory blocks with the 14,940 weight-variables. PSO was implemented on CPU (dual-Xeon, 3.1GHz) and GPU (dual-K20 Tesla, 2496 cores, 3.52Tflops, each) platforms. NiftyReg, an open-source deformable image registration package, was used to calculate the summed dose. Results The 4D-PSO plan yielded PTV coverage comparable to the clinical ITV-based plan and significantly higher OAR-sparing, as follows: lung Dmean=33%; lung V20=27%; spinal cord Dmax=26%; esophagus Dmax=42%; heart Dmax=0%; heart Dmean=47%. The GPU-PSO processing time for 14940 variables and 7 PSO-particles was 41% that of CPU-PSO (199 vs. 488 minutes). Conclusion Truly 4D-IMRT planning can yield significant OAR dose-sparing while preserving PTV coverage. The corresponding optimization problem is large-scale, non-convex and computationally rigorous. Our initial

  9. A computational method for estimating the dosimetric effect of intra-fraction motion on step-and-shoot IMRT and compensator plans

    NASA Astrophysics Data System (ADS)

    Waghorn, Ben J.; Shah, Amish P.; Ngwa, Wilfred; Meeks, Sanford L.; Moore, Joseph A.; Siebers, Jeffrey V.; Langen, Katja M.

    2010-07-01

    Intra-fraction organ motion during intensity-modulated radiation therapy (IMRT) treatment can cause differences between the planned and the delivered dose distribution. To investigate the extent of these dosimetric changes, a computational model was developed and validated. The computational method allows for calculation of the rigid motion perturbed three-dimensional dose distribution in the CT volume and therefore a dose volume histogram-based assessment of the dosimetric impact of intra-fraction motion on a rigidly moving body. The method was developed and validated for both step-and-shoot IMRT and solid compensator IMRT treatment plans. For each segment (or beam), fluence maps were exported from the treatment planning system. Fluence maps were shifted according to the target position deduced from a motion track. These shifted, motion-encoded fluence maps were then re-imported into the treatment planning system and were used to calculate the motion-encoded dose distribution. To validate the accuracy of the motion-encoded dose distribution the treatment plan was delivered to a moving cylindrical phantom using a programmed four-dimensional motion phantom. Extended dose response (EDR-2) film was used to measure a planar dose distribution for comparison with the calculated motion-encoded distribution using a gamma index analysis (3% dose difference, 3 mm distance-to-agreement). A series of motion tracks incorporating both inter-beam step-function shifts and continuous sinusoidal motion were tested. The method was shown to accurately predict the film's dose distribution for all of the tested motion tracks, both for the step-and-shoot IMRT and compensator plans. The average gamma analysis pass rate for the measured dose distribution with respect to the calculated motion-encoded distribution was 98.3 ± 0.7%. For static delivery the average film-to-calculation pass rate was 98.7 ± 0.2%. In summary, a computational technique has been developed to calculate the

  10. SU-C-207A-07: Cumulative 18F-FDG Uptake Histogram Relative to Radiation Dose Volume Histogram of Lung After IMRT Or PSPT and Their Association with Radiation Pneumonitis

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Shusharina, N; Choi, N; Bortfeld, T

    2016-06-15

    Purpose: To determine whether the difference in cumulative 18F-FDG uptake histogram of lung treated with either IMRT or PSPT is associated with radiation pneumonitis (RP) in patients with inoperable stage II and III NSCLC. Methods: We analyzed 24 patients from a prospective randomized trial to compare IMRT (n=12) with vs. PSPT (n=12) for inoperable NSCLC. All patients underwent PET-CT imaging between 35 and 88 days post-therapy. Post-treatment PET-CT was aligned with planning 4D CT to establish a voxel-to-voxel correspondence between post-treatment PET and planning dose images. 18F-FDG uptake as a function of radiation dose to normal lung was obtained formore » each patient. Distribution of the standard uptake value (SUV) was analyzed using a volume histogram method. The image quantitative characteristics and DVH measures were correlated with clinical symptoms of pneumonitis. Results: Patients with RP were present in both groups: 5 in the IMRT and 6 in the PSPT. The analysis of cumulative SUV histograms showed significantly higher relative volumes of the normal lung having higher SUV uptake in the PSPT patients for both symptomatic and asymptomatic cases (VSUV=2: 10% for IMRT vs 16% for proton RT and VSUV=1: 10% for IMRT vs 23% for proton RT). In addition, the SUV histograms for symptomatic cases in PSPT patients exhibited a significantly longer tail at the highest SUV. The absolute volume of the lung receiving the dose >70 Gy was larger in the PSPT patients. Conclusion: 18F-FDG uptake – radiation dose response correlates with RP in both groups of patients by means of the linear regression slope. SUV is higher for the PSPT patients for both symptomatic and asymptomatic cases. Higher uptake after PSPT patients is explained by larger volumes of the lung receiving high radiation dose.« less

  11. Analysis of dose-volume parameters predicting radiation pneumonitis in patients with esophageal cancer treated with 3D-conformal radiation therapy or IMRT.

    PubMed

    Kumar, Gaurav; Rawat, Sheh; Puri, Abhishek; Sharma, Manoj Kumar; Chadha, Pranav; Babu, Anand Giri; Yadav, Girigesh

    2012-01-01

    Multimodality therapy for esophageal cancer can cause various kinds of treatment-related sequelae, especially pulmonary toxicities. This prospective study aims to investigate the clinical and dosimetric parameters predicting lung injury in patients undergoing radiation therapy for esophageal cancer. Forty-five esophageal cancer patients were prospectively analyzed. The pulmonary toxicities (or sequelae) were evaluated by comparing chest X-ray films, pulmonary function tests and symptoms caused by pulmonary damage before and after treatment. All patients were treated with either three-dimensional radiotherapy (3DCRT) or with intensity-modulated radiotherapy (IMRT). The planning dose volume histogram was used to compute the lung volumes receiving more than 5, 10, 20 and 30 Gy (V5, V10, V20, V30) and mean lung dose. V20 was larger in the IMRT group than in the 3DCRT group (p = 0.002). V20 (>15%) and V30 (>20%) resulted in a statistically significant increase in the occurrence of chronic pneumonitis (p = 0.03) and acute pneumonitis (p = 0.007), respectively. The study signifies that a larger volume of lung receives lower doses because of multiple beam arrangement and a smaller volume of lung receives higher doses because of better dose conformity in IMRT plans. Acute pneumonitis correlates more with V30 values, whereas chronic pneumonitis was predominantly seen in patients with higher V20 values.

  12. Helical tomotherapy to LINAC plan conversion utilizing RayStation Fallback planning.

    PubMed

    Zhang, Xin; Penagaricano, Jose; Narayanasamy, Ganesh; Corry, Peter; Liu, TianXiao; Sanjay, Maraboyina; Paudel, Nava; Morrill, Steven

    2017-01-01

    RaySearch RayStation Fallback (FB) planning module can generate an equivalent backup radiotherapy treatment plan facilitating treatment on other linear accelerators. FB plans were generated from the RayStation FB module by simulating the original plan target and organ at risk (OAR) dose distribution and delivered in various backup linear accelerators. In this study, helical tomotherapy (HT) backup plans used in Varian TrueBeam linear accelerator were generated with the RayStation FB module. About 30 patients, 10 with lung cancer, 10 with head and neck (HN) cancer, and 10 with prostate cancer, who were treated with HT, were included in this study. Intensity-modulated radiotherapy Fallback plans (FB-IMRT) were generated for all patients, and three-dimensional conformal radiotherapy Fallback plans (FB-3D) were only generated for lung cancer patients. Dosimetric comparison study evaluated FB plans based on dose coverage to 95% of the PTV volume (R 95 ), PTV mean dose (D mean ), Paddick's conformity index (CI), and dose homogeneity index (HI). The evaluation results showed that all IMRT plans were statistically comparable between HT and FB-IMRT plans except that PTV HI was worse in prostate, and PTV R 95 and HI were worse in HN multitarget plans for FB-IMRT plans. For 3D lung cancer plans, only the PTV R 95 was statistically comparable between HT and FB-3D plans, PTV D mean was higher, and CI and HI were worse compared to HT plans. The FB plans using a TrueBeam linear accelerator generally offer better OAR sparing compared to HT plans for all the patients. In this study, all cases of FB-IMRT plans and 9/10 cases of FB-3D plans were clinically acceptable without further modification and optimization once the FB plans were generated. However, the statistical differences between HT and FB-IMRT/3D plans might not be of any clinically significant. One FB-3D plan failed to simulate the original plan without further optimization. © 2017 The Authors. Journal of Applied

  13. Lhermitte Sign After Chemo-IMRT of Head-and-Neck Cancer: Incidence, Doses, and Potential Mechanisms

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Pak, Daniel; Vineberg, Karen; Feng, Felix

    2012-08-01

    Purpose: We have observed a higher rate of Lhermitte sign (LS) after chemo-intensity-modulated radiotherapy (IMRT) of head-and-neck cancer than the published rates after conventional radiotherapy. We hypothesized that the inhomogeneous spinal cord dose distributions produced by IMRT caused a 'bath-and-shower' effect, characterized by low doses in the vicinity of high doses, reducing spinal cord tolerance. Methods and Materials: Seventy-three patients with squamous cell carcinoma of the oropharynx participated in a prospective study of IMRT concurrent with weekly carboplatin and paclitaxel. Of these, 15 (21%) reported LS during at least 2 consecutive follow-up visits. Mean dose, maximum dose, and partial volumemore » and absolute volume (in milliliters) of spinal cord receiving specified doses ({>=}10 Gy, {>=}20 Gy, {>=}30 Gy, and {>=}40 Gy), as well as the pattern of dose distributions at the 'anatomic' spinal cord (from the base of the skull to the aortic arch) and 'plan-related' spinal cord (from the top through the bottom of the planning target volumes), were compared between LS patients and 34 non-LS patients. Results: LS patients had significantly higher spinal cord mean doses, V{sub 30}, V{sub 40}, and absolute volumes receiving 30 Gy or more and 40 Gy or more compared with the non-LS patients (p < 0.05). The strongest predictors of LS were higher V{sub 40} and higher cord volumes receiving 40 Gy or more (p {<=} 0.007). There was no evidence of larger spinal cord volumes receiving low doses in the vicinity of higher doses (bath-and-shower effect) in LS compared with non-LS patients. Conclusions: Greater mean dose, V{sub 30}, V{sub 40}, and cord volumes receiving 30 Gy or more and 40 Gy or more characterized LS compared with non-LS patients. Bath-and-shower effects could not be validated in this study as a potential contributor to LS. The higher-than-expected rates of LS may be because of the specific concurrent chemotherapy agents or more accurate

  14. Modeling the target dose fall-off in IMRT and VMAT planning techniques for cervical SBRT.

    PubMed

    Brito Delgado, A; Cohen, D; Eng, T Y; Stanley, D N; Shi, Z; Charlton, M; Gutiérrez, A N

    2018-01-01

    There has been growing interest in the use of stereotactic body radiotherapy (SBRT) technique for the treatment of cervical cancer. The purpose of this study was to characterize dose distributions as well as model the target dose fall-off for intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT) delivery techniques using 6 and 10 MV photon beam energies. Fifteen (n = 15) patients with non-bulky cervical tumors were planned in Pinnacle 3 with a Varian Novalis Tx (HD120 MLC) using 6 and 10 MV photons with the following techniques: (1) IMRT with 10 non-coplanar beams (2) dual, coplanar 358° VMAT arcs (4° spacing), and (3) triple, non-coplanar VMAT arcs. Treatment volumes and dose prescriptions were segmented according to University of Texas Southwestern (UTSW) Phase II study. All plans were normalized such that 98% of the planning target volume (PTV) received 28 Gy (4 fractions). For the PTV, the following metrics were evaluated: homogeneity index, conformity index, D 2cc , D mean , D max , and dose fall-off parameters. For the organs at risk (OARs), D 2cc , D 15cc , D 0.01cc , V 20 , V 40 , V 50 , V 60 , and V 80 were evaluated for the bladder, bowel, femoral heads, rectum, and sigmoid. Statistical differences were evaluated using a Friedman test with a significance level of 0.05. To model dose fall-off, expanding 2-mm-thick concentric rings were created around the PTV, and doses were recorded. Statistically significant differences (p < 0.05) were noted in the dose fall-off when using 10 MV and VMAT 3-arc , as compared with IMRT. VMAT 3-arc improved the bladder V 40 , V 50 , and V 60 , and the bowel V 20 and V 50 . All fitted regressions had an R 2  ≥ 0.98. For cervical SBRT plans, a VMAT 3-arc approach offers a steeper dose fall-off outside of the target volume. Faster dose fall-off was observed in smaller targets as opposed to medium and large targets, denoting that OAR sparing is dependent on target size. These

  15. Thyroid V50 Highly Predictive of Hypothyroidism in Head-and-Neck Cancer Patients Treated With Intensity-modulated Radiotherapy (IMRT).

    PubMed

    Sachdev, Sean; Refaat, Tamer; Bacchus, Ian D; Sathiaseelan, Vythialinga; Mittal, Bharat B

    2017-08-01

    Radiation-induced hypothyroidism affects a significant number of patients with head-and-neck squamous cell cancer (HNSCC). We examined detailed dosimetric and clinical parameters to better determine the risk of hypothyroidism in euthyroid HNSCC patients treated with intensity-modulated radiation therapy (IMRT). From 2006 to 2010, 75 clinically euthyroid patients with HNSCC were treated with sequential IMRT. The cohort included 59 men and 16 females with a median age of 55 years (range, 30 to 89 y) who were treated to a median dose of 70 Gy (range, 60 to 75 Gy) with concurrent chemotherapy in nearly all (95%) cases. Detailed thyroid dosimetric parameters including maximum dose, mean dose, and other parameters (eg, V50-percent volume receiving at least 50 Gy) were obtained. Freedom from hypothyroidism was evaluated using the Kaplan-Meier method. Univariate and multivariate analyses were conducted using Cox regression. After a median follow-up period of 50 months, 25 patients (33%) became hypothyroid. On univariate analysis, thyroid V50 was highly correlated with developing hypothyroidism (P=0.035). Other dosimetric paramaters including mean thyroid dose (P=0.11) and maximum thyroid dose (P=0.39) did not reach statistical significance. On multivariate analysis incorporating patient, tumor, and treatment variables, V50 remained highly statistically significant (P=0.037). Regardless of other factors, for V50>60%, the odds ratio of developing hypothyroidism was 6.76 (P=0.002). In HNSCC patients treated with IMRT, thyroid V50 highly predicts the risk of developing hypothyroidism. V50>60% puts patients at a significantly higher risk of becoming hypothyroid. This can be a useful dose constraint to consider during treatment planning.

  16. Anatomy-corresponding method of IMRT verification.

    PubMed

    Winiecki, Janusz; Zurawski, Zbigniew; Drzewiecka, Barbara; Slosarek, Krzysztof

    2010-01-01

    During a proper execution of dMLC plans, there occurs an undesired but frequent effect of the dose locally accumulated by tissue being significantly different than expected. The conventional dosimetric QA procedures give only a partial picture of the quality of IMRT treatment, because their solely quantitative outcomes usually correspond more to the total area of the detector than the actually irradiated volume. The aim of this investigation was to develop a procedure of dynamic plans verification which would be able to visualize the potential anomalies of dose distribution and specify which tissue they exactly refer to. The paper presents a method discovered and clinically examined in our department. It is based on a Gamma Evaluation concept and allows accurate localization of deviations between predicted and acquired dose distributions, which were registered by portal as well as film dosimetry. All the calculations were performed on the self-made software GammaEval, the γ-images (2-dimensional distribution of γ-values) and γ-histograms were created as quantitative outcomes of verification. Over 150 maps of dose distribution have been analyzed and the cross-examination of the gamma images with DRRs was performed. It seems, that the complex monitoring of treatment would be possible owing to the images obtained as a cross-examination of γ-images and corresponding DRRs.

  17. Use of plan quality degradation to evaluate tradeoffs in delivery efficiency and clinical plan metrics arising from IMRT optimizer and sequencer compromises

    PubMed Central

    Wilkie, Joel R.; Matuszak, Martha M.; Feng, Mary; Moran, Jean M.; Fraass, Benedick A.

    2013-01-01

    Purpose: Plan degradation resulting from compromises made to enhance delivery efficiency is an important consideration for intensity modulated radiation therapy (IMRT) treatment plans. IMRT optimization and/or multileaf collimator (MLC) sequencing schemes can be modified to generate more efficient treatment delivery, but the effect those modifications have on plan quality is often difficult to quantify. In this work, the authors present a method for quantitative assessment of overall plan quality degradation due to tradeoffs between delivery efficiency and treatment plan quality, illustrated using comparisons between plans developed allowing different numbers of intensity levels in IMRT optimization and/or MLC sequencing for static segmental MLC IMRT plans. Methods: A plan quality degradation method to evaluate delivery efficiency and plan quality tradeoffs was developed and used to assess planning for 14 prostate and 12 head and neck patients treated with static IMRT. Plan quality was evaluated using a physician's predetermined “quality degradation” factors for relevant clinical plan metrics associated with the plan optimization strategy. Delivery efficiency and plan quality were assessed for a range of optimization and sequencing limitations. The “optimal” (baseline) plan for each case was derived using a clinical cost function with an unlimited number of intensity levels. These plans were sequenced with a clinical MLC leaf sequencer which uses >100 segments, assuring delivered intensities to be within 1% of the optimized intensity pattern. Each patient's optimal plan was also sequenced limiting the number of intensity levels (20, 10, and 5), and then separately optimized with these same numbers of intensity levels. Delivery time was measured for all plans, and direct evaluation of the tradeoffs between delivery time and plan degradation was performed. Results: When considering tradeoffs, the optimal number of intensity levels depends on the treatment

  18. Patient geometry-driven information retrieval for IMRT treatment plan quality control

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wu Binbin; Ricchetti, Francesco; Sanguineti, Giuseppe

    Purpose: Intensity modulated radiation therapy (IMRT) treatment plan quality depends on the planner's level of experience and the amount of time the planner invests in developing the plan. Planners often unwittingly accept plans when further sparing of the organs at risk (OARs) is possible. The authors propose a method of IMRT treatment plan quality control that helps planners to evaluate the doses of the OARs upon completion of a new plan. Methods: It is achieved by comparing the geometric configurations of the OARs and targets of a new patient with those of prior patients, whose plans are maintained in amore » database. They introduce the concept of a shape relationship descriptor and, specifically, the overlap volume histogram (OVH) to describe the spatial configuration of an OAR with respect to a target. The OVH provides a way to infer the likely DVHs of the OARs by comparing the relative spatial configurations between patients. A database of prior patients is built to serve as an external reference. At the conclusion of a new plan, planners search through the database and identify related patients by comparing the OAR-target geometric relationships of the new patient with those of prior patients. The treatment plans of these related patients are retrieved from the database and guide planners in determining whether lower doses delivered to the OARs in the new plan are feasible. Results: Preliminary evaluation is promising. In this evaluation, they applied the analysis to the parotid DVHs of 32 prior head-and-neck patients, whose plans are maintained in a database. Each parotid was queried against the other 63 parotids to determine whether a lower dose was possible. The 17 parotids that promised the greatest reduction in D{sub 50} (DVH dose at 50% volume) were flagged. These 17 parotids came from 13 patients. The method also indicated that the doses of the other nine parotids of the 13 patients could not be reduced, so they were included in the replanning

  19. SU-F-T-315: Comparative Studies of Planar Dose with Different Spatial Resolution for Head and Neck IMRT QA

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hwang, T; Koo, T

    Purpose: To quantitatively investigate the planar dose difference and the γ value between the reference fluence map with the 1 mm detector-to-detector distance and the other fluence maps with less spatial resolution for head and neck intensity modulated radiation (IMRT) therapy. Methods: For ten head and neck cancer patients, the IMRT quality assurance (QA) beams were generated using by the commercial radiation treatment planning system, Pinnacle3 (ver. 8.0.d Philips Medical System, Madison, WI). For each beam, ten fluence maps (detector-to-detector distance: 1 mm to 10 mm by 1 mm) were generated. The fluence maps with larger than 1 mm detector-todetectormore » distance were interpolated using MATLAB (R2014a, the Math Works,Natick, MA) by four different interpolation Methods: for the bilinear, the cubic spline, the bicubic, and the nearest neighbor interpolation, respectively. These interpolated fluence maps were compared with the reference one using the γ value (criteria: 3%, 3 mm) and the relative dose difference. Results: As the detector-to-detector distance increases, the dose difference between the two maps increases. For the fluence map with the same resolution, the cubic spline interpolation and the bicubic interpolation are almost equally best interpolation methods while the nearest neighbor interpolation is the worst.For example, for 5 mm distance fluence maps, γ≤1 are 98.12±2.28%, 99.48±0.66%, 99.45±0.65% and 82.23±0.48% for the bilinear, the cubic spline, the bicubic, and the nearest neighbor interpolation, respectively. For 7 mm distance fluence maps, γ≤1 are 90.87±5.91%, 90.22±6.95%, 91.79±5.97% and 71.93±4.92 for the bilinear, the cubic spline, the bicubic, and the nearest neighbor interpolation, respectively. Conclusion: We recommend that the 2-dimensional detector array with high spatial resolution should be used as an IMRT QA tool and that the measured fluence maps should be interpolated using by the cubic spline interpolation or

  20. Potential for reduced toxicity and dose escalation in the treatment of inoperable non-small-cell lung cancer: a comparison of intensity-modulated radiation therapy (IMRT), 3D conformal radiation, and elective nodal irradiation.

    PubMed

    Grills, Inga S; Yan, Di; Martinez, Alvaro A; Vicini, Frank A; Wong, John W; Kestin, Larry L

    2003-11-01

    To systematically evaluate four different techniques of radiation therapy (RT) used to treat non-small-cell lung cancer and to determine their efficacy in meeting multiple normal-tissue constraints while maximizing tumor coverage and achieving dose escalation. Treatment planning was performed for 18 patients with Stage I to IIIB inoperable non-small-cell lung cancer using four different RT techniques to treat the primary lung tumor +/- the hilar/mediastinal lymph nodes: (1) Intensity-modulated radiation therapy (IMRT), (2) Optimized three-dimensional conformal RT (3D-CRT) using multiple beam angles, (3) Limited 3D-CRT using only 2 to 3 beams, and (4) Traditional RT using elective nodal irradiation (ENI) to treat the mediastinum. All patients underwent virtual simulation, including a CT scan and (18)fluorodeoxyglucose positron emission tomography scan, fused to the CT to create a composite tumor volume. For IMRT and 3D-CRT, the target included the primary tumor and regional nodes either > or =1.0 cm in short-axis dimension on CT or with increased uptake on PET. For ENI, the target included the primary tumor plus the ipsilateral hilum and mediastinum from the inferior head of the clavicle to at least 5.0 cm below the carina. The goal was to deliver 70 Gy to > or =99% of the planning target volume (PTV) in 35 daily fractions (46 Gy to electively treated mediastinum) while meeting multiple normal-tissue dose constraints. Heterogeneity correction was applied to all dose calculations (maximum allowable heterogeneity within PTV 30%). Pulmonary and esophageal constraints were as follows: lung V(20) < or =25%, mean lung dose < or =15 Gy, esophagus V(50) < or =25%, mean esophageal dose < or =25 Gy. At the completion of all planning, the four techniques were contrasted for their ability to achieve the set dose constraints and deliver tumoricidal RT doses. Requiring a minimum dose of 70 Gy within the PTV, we found that IMRT was associated with a greater degree of heterogeneity

  1. IMRT for head and neck cancer: reducing xerostomia and dysphagia

    PubMed Central

    Wang, XiaoShen; Eisbruch, Avraham

    2016-01-01

    Dysphagia and xerostomia are the main sequellae of chemoradiotherapy for head and neck cancer, and the main factors in reducing long-term patient quality of life. IMRT uses advanced technology to focus the high radiation doses on the targets and avoid irradiation of non-involved tissues. The decisions about sparing organs and tissues whose damage causes xerostomia and dysphagia depends on the evidence for dose–response relationships for the organs causing these sequellae. This paper discusses the evidence for the contribution of radiotherapy to xerostomia via damage of the major salivary glands (parotid and submandibular) and minor salivary glands within the oral cavity, and the contribution of radiotherapy-related effect on important swallowing structures causing dysphagia. Recommendations for dose limits to these organs, based on measurements of xerostomia and dysphagia following radiotherapy, are provided here. PMID:27538846

  2. SU-F-T-350: Continuous Leaf Optimization (CLO) for IMRT Leaf Sequencing

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Long, T; Chen, M; Jiang, S

    Purpose: To study a new step-and-shoot IMRT leaf sequencing model that avoids the two main pitfalls of conventional leaf sequencing: (1) target fluence being stratified into a fixed number of discrete levels and/or (2) aperture leaf positions being restricted to a discrete set of locations. These assumptions induce error into the sequence or reduce the feasible region of potential plans, respectively. Methods: We develop a one-dimensional (single leaf pair) methodology that does not make assumptions (1) or (2) that can be easily extended to a multi-row model. The proposed continuous leaf optimization (CLO) methodology takes in an existing set ofmore » apertures and associated intensities, or solution “seed,” and improves the plan without the restrictiveness of 1or (2). It then uses a first-order descent algorithm to converge onto a locally optimal solution. A seed solution can come from models that assume (1) and (2), thus allowing the CLO model to improve upon existing leaf sequencing methodologies. Results: The CLO model was applied to 208 generated target fluence maps in one dimension. In all cases for all tested sequencing strategies, the CLO model made improvements on the starting seed objective function. The CLO model also was able to keep MUs low. Conclusion: The CLO model can improve upon existing leaf sequencing methods by avoiding the restrictions of (1) and (2). By allowing for more flexible leaf positioning, error can be reduced when matching some target fluence. This study lays the foundation for future models and solution methodologies that can incorporate continuous leaf positions explicitly into the IMRT treatment planning model. Supported by Cancer Prevention & Research Institute of Texas (CPRIT) - ID RP150485.« less

  3. Analysis of Intensity-Modulated Radiation Therapy (IMRT), Proton and 3D Conformal Radiotherapy (3D-CRT) for Reducing Perioperative Cardiopulmonary Complications in Esophageal Cancer Patients.

    PubMed

    Ling, Ted C; Slater, Jerry M; Nookala, Prashanth; Mifflin, Rachel; Grove, Roger; Ly, Anh M; Patyal, Baldev; Slater, Jerry D; Yang, Gary Y

    2014-12-05

    Background. While neoadjuvant concurrent chemoradiotherapy has improved outcomes for esophageal cancer patients, surgical complication rates remain high. The most frequent perioperative complications after trimodality therapy were cardiopulmonary in nature. The radiation modality utilized can be a strong mitigating factor of perioperative complications given the location of the esophagus and its proximity to the heart and lungs. The purpose of this study is to make a dosimetric comparison of Intensity-Modulated Radiation Therapy (IMRT), proton and 3D conformal radiotherapy (3D-CRT) with regard to reducing perioperative cardiopulmonary complications in esophageal cancer patients. Materials. Ten patients with esophageal cancer treated between 2010 and 2013 were evaluated in this study. All patients were simulated with contrast-enhanced CT imaging. Separate treatment plans using proton radiotherapy, IMRT, and 3D-CRT modalities were created for each patient. Dose-volume histograms were calculated and analyzed to compare plans between the three modalities. The organs at risk (OAR) being evaluated in this study are the heart, lungs, and spinal cord. To determine statistical significance, ANOVA and two-tailed paired t-tests were performed for all data parameters. Results. The proton plans showed decreased dose to various volumes of the heart and lungs in comparison to both the IMRT and 3D-CRT plans. There was no difference between the IMRT and 3D-CRT plans in dose delivered to the lung or heart. This finding was seen consistently across the parameters analyzed in this study. Conclusions. In patients receiving radiation therapy for esophageal cancer, proton plans are technically feasible while achieving adequate coverage with lower doses delivered to the lungs and cardiac structures. This may result in decreased cardiopulmonary toxicity and less morbidity to esophageal cancer patients.

  4. Analysis of Intensity-Modulated Radiation Therapy (IMRT), Proton and 3D Conformal Radiotherapy (3D-CRT) for Reducing Perioperative Cardiopulmonary Complications in Esophageal Cancer Patients

    PubMed Central

    Ling, Ted C.; Slater, Jerry M.; Nookala, Prashanth; Mifflin, Rachel; Grove, Roger; Ly, Anh M.; Patyal, Baldev; Slater, Jerry D.; Yang, Gary Y.

    2014-01-01

    Background. While neoadjuvant concurrent chemoradiotherapy has improved outcomes for esophageal cancer patients, surgical complication rates remain high. The most frequent perioperative complications after trimodality therapy were cardiopulmonary in nature. The radiation modality utilized can be a strong mitigating factor of perioperative complications given the location of the esophagus and its proximity to the heart and lungs. The purpose of this study is to make a dosimetric comparison of Intensity-Modulated Radiation Therapy (IMRT), proton and 3D conformal radiotherapy (3D-CRT) with regard to reducing perioperative cardiopulmonary complications in esophageal cancer patients. Materials. Ten patients with esophageal cancer treated between 2010 and 2013 were evaluated in this study. All patients were simulated with contrast-enhanced CT imaging. Separate treatment plans using proton radiotherapy, IMRT, and 3D-CRT modalities were created for each patient. Dose-volume histograms were calculated and analyzed to compare plans between the three modalities. The organs at risk (OAR) being evaluated in this study are the heart, lungs, and spinal cord. To determine statistical significance, ANOVA and two-tailed paired t-tests were performed for all data parameters. Results. The proton plans showed decreased dose to various volumes of the heart and lungs in comparison to both the IMRT and 3D-CRT plans. There was no difference between the IMRT and 3D-CRT plans in dose delivered to the lung or heart. This finding was seen consistently across the parameters analyzed in this study. Conclusions. In patients receiving radiation therapy for esophageal cancer, proton plans are technically feasible while achieving adequate coverage with lower doses delivered to the lungs and cardiac structures. This may result in decreased cardiopulmonary toxicity and less morbidity to esophageal cancer patients. PMID:25489937

  5. [Dosimetric comparison of non-small cell lung cancer treatment with multi fields dynamic-MLC IMRT].

    PubMed

    Hao, Longying; Wang, Delin; Cao, Yujuan; Du, Fang; Cao, Feng; Liu, Chengwei

    2015-05-19

    We compared the dosimetric differences between the target and surrounding tissues/organs of the 5-field and 7,9-field (Hereinafter referred to as F5, F7, F9) treatment plan in non-small cell lung cancer (NSCLC) by the dynamic intensity-modulated radiotherapy (dIMRT), to provide reference for clinical application. Using Varian planning system (Eclipse 7.3), we randomly selected 30 cases of patients who received dIMRT to study, all patients were 5, 7, 9 fixed field dynamics intensity-modulated radiotherapy plans to meet the target prescription requirements (95% dose curve enveloping 100% of the PTV), by comparing dose-volume histogram DVH evaluation, and the maximum dose D(max), the minimum dose D(min), and the mean dose D(mean), and conformal index CI of PTV,organs at risk of spinal cord the maximum dose D(max), lung V(5), V(10), V(20), V(30), heart V(30) and esophageal V(50), V(60) of F5,F7 and F9 dIMRT plans,and compare the mu of the three treatment programs. The D(max), D(min) and D(mean) values of F5's PTV are (7 203 ± 128), (5 493 ± 331), (6 900 ± 138) cGy respectively; the D(max), D(min) and D(mean) values of F7's PTV are (7 304 ± 96), (5 526 ± 296), (6 976 ± 130) cGy respectively; and the D(max), D(min) and D(mean) values of F9's PTV are (7 356 ± 54), (5 578 ± 287), (7 019 ± 56) cGy respectively. The data shows that while we increased the numbers of fields, the isodose line surrounding the target area would also promote slightly. The conformity index CI of target became better with the increase of radiation fields. The whole lung V(5) and V(10) slightly became larger with increase of fields and the V(20) showed no significant difference in three models, V(30) of double lungs slightly decreased with the increase of fields. The above date was statistically meaningless (P > 0.05). With the increase of fields esophagus V(50) were reduced by 3% and 5% respectively, V(60) of the esophagus were reduced by 6% and 11%, the average dose reduced by 5% and 10

  6. Decline of Cosmetic Outcomes Following Accelerated Partial Breast Irradiation Using Intensity Modulated Radiation Therapy: Results of a Single-Institution Prospective Clinical Trial

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Liss, Adam L.; Ben-David, Merav A.; Jagsi, Reshma

    2014-05-01

    Purpose: To report the final cosmetic results from a single-arm prospective clinical trial evaluating accelerated partial breast irradiation (APBI) using intensity modulated radiation therapy (IMRT) with active-breathing control (ABC). Methods and Materials: Women older than 40 with breast cancer stages 0-I who received breast-conserving surgery were enrolled in an institutional review board-approved prospective study evaluating APBI using IMRT administered with deep inspiration breath-hold. Patients received 38.5 Gy in 3.85-Gy fractions given twice daily over 5 consecutive days. The planning target volume was defined as the lumpectomy cavity with a 1.5-cm margin. Cosmesis was scored on a 4-category scale by themore » treating physician. Toxicity was scored according to National Cancer Institute Common Terminology Criteria for Adverse Events (CTCAE version 3.0). We report the cosmetic and toxicity results at a median follow-up of 5 years. Results: A total of 34 patients were enrolled. Two patients were excluded because of fair baseline cosmesis. The trial was terminated early because fair/poor cosmesis developed in 7 of 32 women at a median follow-up of 2.5 years. At a median follow-up of 5 years, further decline in the cosmetic outcome was observed in 5 women. Cosmesis at the time of last assessment was 43.3% excellent, 30% good, 20% fair, and 6.7% poor. Fibrosis according to CTCAE at last assessment was 3.3% grade 2 toxicity and 0% grade 3 toxicity. There was no correlation of CTCAE grade 2 or greater fibrosis with cosmesis. The 5-year rate of local control was 97% for all 34 patients initially enrolled. Conclusions: In this prospective trial with 5-year median follow-up, we observed an excellent rate of tumor control using IMRT-planned APBI. Cosmetic outcomes, however, continued to decline, with 26.7% of women having a fair to poor cosmetic result. These results underscore the need for continued cosmetic assessment for patients treated with APBI by technique.« less

  7. [Accelerated partial breast irradiation with image-guided intensity-modulated radiotherapy following breast-conserving surgery - preliminary results of a phase II clinical study].

    PubMed

    Mészáros, Norbert; Major, Tibor; Stelczer, Gábor; Zaka, Zoltán; Mózsa, Emõke; Fodor, János; Polgár, Csaba

    2015-06-01

    The purpose of the study was to implement accelerated partial breast irradiation (APBI) by means of image-guided intensity-modulated radiotherapy (IG-IMRT) following breast-conserving surgery (BCS) for low-risk early invasive breast cancer. Between July 2011 and March 2014, 60 patients with low-risk early invasive (St I-II) breast cancer who underwent BCS were enrolled in our phase II prospective study. Postoperative APBI was given by means of step and shoot IG-IMRT using 4 to 5 fields to a total dose of 36.9 Gy (9×4.1 Gy) using a twice-a-day fractionation. Before each fraction, series of CT images were taken from the region of the target volume using a kV CT on-rail mounted in the treatment room. An image fusion software was used for automatic image registration of the planning and verification CT images. Patient set-up errors were detected in three directions (LAT, LONG, VERT), and inaccuracies were adjusted by automatic movements of the treatment table. Breast cancer related events, acute and late toxicities, and cosmetic results were registered and analysed. At a median follow-up of 24 months (range 12-44) neither locoregional nor distant failure was observed. Grade 1 (G1), G2 erythema, G1 oedema, and G1 and G2 pain occurred in 21 (35%), 2 (3.3%), 23 (38.3%), 6 (10%) and 2 (3.3%) patients, respectively. No G3-4 acute side effects were detected. Among late radiation side effects G1 pigmentation, G1 fibrosis, and G1 fat necrosis occurred in 5 (8.3%), 7 (11.7%), and 2 (3.3%) patients, respectively. No ≥G2 late toxicity was detected. Excellent and good cosmetic outcome was detected in 45 (75%) and 15 (25%) patients. IG-IMRT is a reproducible and feasible technique for the delivery of APBI following conservative surgery for the treatment of low-risk, early-stage invasive breast carcinoma. Preliminary results are promising, early radiation side effects are minimal, and cosmetic results are excellent.

  8. The Pattern of Failure After Reirradiation of Recurrent Squamous Cell Head and Neck Cancer: Implications for Defining the Targets

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Popovtzer, Aron; Gluck, Iris; Chepeha, Douglas B.

    2009-08-01

    Purpose: Reirradiation (re-RT) of recurrent head and neck cancer (HNC) may achieve long-term disease control in some patients, at the expense of high rates of late sequelae. Limiting the re-RT targets to the recurrent gross tumor volume (rGTV) would reduce the volumes of reirradiated tissues; however, its effect on tumor recurrence pattern is unknown. Methods and Materials: This is a retrospective review of 66 patients who underwent curative-intent re-RT for nonresectable recurrent or second primary mucosal squamous cell HNC. Treatment was delivered with three-dimensional conformal (3D) RT or intensity-modulated RT (IMRT). The targets in all patients consisted of the rGTVsmore » with tight (0.5-cm) margins, with no intent to treat prophylactically lymph nodes or subclinical disease in the vicinity of the rGTVs. The sites of locoregional failures (LRFs) were determined using imaging at the time of failure and were compared with the rGTVs. Results: Median re-RT dose was 68 Gy. Forty-seven patients (71%) received concomitant chemotherapy, and 31 (47%) received hyperfractionated, accelerated RT. At a median follow-up of 42 months, 16 (23%) were alive and disease-free. Fifty patients (77%) had a third recurrence or persistent disease, including 47 LRFs. All LRFs occurred within the rGTVs except for two (4%) (95% confidence interval, 0-11%). Nineteen patients (29%) had Grade {>=} 3 late complications, mostly dysphagia (12 patients). Conclusions: Almost all LRFs occurred within the reirradiated rGTVs despite avoiding prophylactic RT of tissue at risk of subclinical disease. These results support confining the re-RT targets to the rGTVs to reduce reirradiated tissue volumes.« less

  9. The use of spatial dose gradients and probability density function to evaluate the effect of internal organ motion for prostate IMRT treatment planning

    NASA Astrophysics Data System (ADS)

    Jiang, Runqing; Barnett, Rob B.; Chow, James C. L.; Chen, Jeff Z. Y.

    2007-03-01

    The aim of this study is to investigate the effects of internal organ motion on IMRT treatment planning of prostate patients using a spatial dose gradient and probability density function. Spatial dose distributions were generated from a Pinnacle3 planning system using a co-planar, five-field intensity modulated radiation therapy (IMRT) technique. Five plans were created for each patient using equally spaced beams but shifting the angular displacement of the beam by 15° increments. Dose profiles taken through the isocentre in anterior-posterior (A-P), right-left (R-L) and superior-inferior (S-I) directions for IMRT plans were analysed by exporting RTOG file data from Pinnacle. The convolution of the 'static' dose distribution D0(x, y, z) and probability density function (PDF), denoted as P(x, y, z), was used to analyse the combined effect of repositioning error and internal organ motion. Organ motion leads to an enlarged beam penumbra. The amount of percentage mean dose deviation (PMDD) depends on the dose gradient and organ motion probability density function. Organ motion dose sensitivity was defined by the rate of change in PMDD with standard deviation of motion PDF and was found to increase with the maximum dose gradient in anterior, posterior, left and right directions. Due to common inferior and superior field borders of the field segments, the sharpest dose gradient will occur in the inferior or both superior and inferior penumbrae. Thus, prostate motion in the S-I direction produces the highest dose difference. The PMDD is within 2.5% when standard deviation is less than 5 mm, but the PMDD is over 2.5% in the inferior direction when standard deviation is higher than 5 mm in the inferior direction. Verification of prostate organ motion in the inferior directions is essential. The margin of the planning target volume (PTV) significantly impacts on the confidence of tumour control probability (TCP) and level of normal tissue complication probability (NTCP

  10. The use of spatial dose gradients and probability density function to evaluate the effect of internal organ motion for prostate IMRT treatment planning.

    PubMed

    Jiang, Runqing; Barnett, Rob B; Chow, James C L; Chen, Jeff Z Y

    2007-03-07

    The aim of this study is to investigate the effects of internal organ motion on IMRT treatment planning of prostate patients using a spatial dose gradient and probability density function. Spatial dose distributions were generated from a Pinnacle3 planning system using a co-planar, five-field intensity modulated radiation therapy (IMRT) technique. Five plans were created for each patient using equally spaced beams but shifting the angular displacement of the beam by 15 degree increments. Dose profiles taken through the isocentre in anterior-posterior (A-P), right-left (R-L) and superior-inferior (S-I) directions for IMRT plans were analysed by exporting RTOG file data from Pinnacle. The convolution of the 'static' dose distribution D0(x, y, z) and probability density function (PDF), denoted as P(x, y, z), was used to analyse the combined effect of repositioning error and internal organ motion. Organ motion leads to an enlarged beam penumbra. The amount of percentage mean dose deviation (PMDD) depends on the dose gradient and organ motion probability density function. Organ motion dose sensitivity was defined by the rate of change in PMDD with standard deviation of motion PDF and was found to increase with the maximum dose gradient in anterior, posterior, left and right directions. Due to common inferior and superior field borders of the field segments, the sharpest dose gradient will occur in the inferior or both superior and inferior penumbrae. Thus, prostate motion in the S-I direction produces the highest dose difference. The PMDD is within 2.5% when standard deviation is less than 5 mm, but the PMDD is over 2.5% in the inferior direction when standard deviation is higher than 5 mm in the inferior direction. Verification of prostate organ motion in the inferior directions is essential. The margin of the planning target volume (PTV) significantly impacts on the confidence of tumour control probability (TCP) and level of normal tissue complication probability

  11. Hyperfractionated or Accelerated Hyperfractionated Re-irradiation with ≥42 Gy in Combination with Paclitaxel for Secondary/Recurrent Head-and-Neck Cancer.

    PubMed

    Rades, Dirk; Bartscht, Tobias; Idel, Christian; Schild, Steven E; Hakim, Samer G

    2018-06-01

    Patients with secondary/ recurrent squamous cell head and neck cancer (SCCHN) have poor prognoses. Outcomes of re-irradiation with ≥42 Gy plus paclitaxel for secondary/recurrent SCCHN are herein presented. Two patients re-irradiated for secondary/recurrent SCCHN were evaluated. Patients received 44.4 Gy (2×1.2 Gy/day) or 42.0 Gy (2×1.5 Gy/day), respectively, plus concurrent paclitaxel (35 mg/m 2 weekly or 20 mg/m 2 twice per week). One patient developed a locoregional recurrence and additional metastases at 12 months after re-irradiation and died at 13 months. The other patient developed multiple bone metastases at 103 months and died at 104 months. Acute toxicities included grade 2 anemia and mucositis in both patients. Radiation dermatitis was grade 2 in one patient and grade 3 in the other. Re-irradiation with 42.0-44.4 Gy given twice daily plus paclitaxel was well tolerated and achieved a favorable response. The results need to be confirmed in a prospective trial. Copyright© 2018, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.

  12. Clinical introduction of a linac head-mounted 2D detector array based quality assurance system in head and neck IMRT.

    PubMed

    Korevaar, Erik W; Wauben, David J L; van der Hulst, Peter C; Langendijk, Johannes A; Van't Veld, Aart A

    2011-09-01

    IMRT QA is commonly performed in a phantom geometry but the clinical interpretation of the results in a 2D phantom plane is difficult. The main objective of our work is to move from film measurement based QA to 3D dose reconstruction in a patient CT scan. In principle, this could be achieved using a dose reconstruction method from 2D detector array measurements as available in the COMPASS system (IBA Dosimetry). The first step in the clinical introduction of this system instead of the currently used film QA procedures is to test the reliability of the dose reconstruction. In this paper we investigated the validation of the method in a homogeneous phantom with the film QA procedure as a reference. We tested whether COMPASS QA results correctly identified treatment plans that did or did not fulfil QA requirements in head and neck (H&N) IMRT. A total number of 24 treatments were selected from an existing database with more than 100 film based H&N IMRT QA results. The QA results were classified as either good, just acceptable or clinically rejected (mean gamma index <0.4, 0.4-0.5 or >0.5, respectively with 3%/3mm criteria). Film QA was repeated and compared to COMPASS QA with a MatriXX detector measurement performed on the same day. Good agreement was found between COMPASS reconstructed dose and film measured dose in a phantom (mean gamma 0.83±0.09, 1SD with 1%/1mm criteria, 0.33±0.04 with 3%/3mm criteria). COMPASS QA results correlated well with film QA, identifying the same patients with less good QA results. Repeated measurements with film and COMPASS showed changes in delivery after a modified MLC calibration, also visible in a standard MLC check in COMPASS. The time required for QA reduced by half by using COMPASS instead of film. Agreement of COMPASS QA results with film based QA supports its clinical introduction for a phantom geometry. A standard MLC calibration check is sensitive to <1mm changes that could be significant in H&N IMRT. These findings offer

  13. Prospective Evaluation of Acute Toxicity and Quality of Life After IMRT and Concurrent Chemotherapy for Anal Canal and Perianal Cancer

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Han, Kathy; Cummings, Bernard J.; Lindsay, Patricia

    Purpose: A prospective cohort study was conducted to evaluate toxicity, quality of life (QOL), and clinical outcomes in patients treated with intensity modulated radiation therapy (IMRT) and concurrent chemotherapy for anal and perianal cancer. Methods and Materials: From June 2008 to November 2010, patients with anal or perianal cancer treated with IMRT were eligible. Radiation dose was 27 Gy in 15 fractions to 36 Gy in 20 fractions for elective targets and 45 Gy in 25 fractions to 63 Gy in 35 fractions for gross targets using standardized, institutional guidelines, with no planned treatment breaks. The chemotherapy regimen was 5-fluorouracil and mitomycin C. Toxicitymore » was graded with the National Cancer Institute Common Terminology Criteria for Adverse Events, version 3. QOL was assessed with the European Organization for Research and Treatment of Cancer (EORTC) QLQ-C30 and CR29 questionnaires. Correlations between dosimetric parameters and both physician-graded toxicities and patient-reported outcomes were evaluated by polyserial correlation. Results: Fifty-eight patients were enrolled. The median follow-up time was 34 months; the median age was 56 years; 52% of patients were female; and 19% were human immunodeficiency virus—positive. Stage I, II, III, and IV disease was found in 9%, 57%, 26%, and 9% of patients, respectively. Twenty-six patients (45%) required a treatment break because of acute toxicity, mainly dermatitis (23/26). Acute grade 3 + toxicities included skin 46%, hematologic 38%, gastrointestinal 9%, and genitourinary 0. The 2-year overall survival (OS), disease-free survival (DFS), colostomy-free survival (CFS), and cumulative locoregional failure (LRF) rates were 90%, 77%, 84%, and 16%, respectively. The global QOL/health status, skin, defecation, and pain scores were significantly worse at the end of treatment than at baseline, but they returned to baseline 3 months after treatment. Social functioning and appetite scores were

  14. A difference-matrix metaheuristic for intensity map segmentation in step-and-shoot IMRT delivery.

    PubMed

    Gunawardena, Athula D A; D'Souza, Warren D; Goadrich, Laura D; Meyer, Robert R; Sorensen, Kelly J; Naqvi, Shahid A; Shi, Leyuan

    2006-05-21

    At an intermediate stage of radiation treatment planning for IMRT, most commercial treatment planning systems for IMRT generate intensity maps that describe the grid of beamlet intensities for each beam angle. Intensity map segmentation of the matrix of individual beamlet intensities into a set of MLC apertures and corresponding intensities is then required in order to produce an actual radiation delivery plan for clinical use. Mathematically, this is a very difficult combinatorial optimization problem, especially when mechanical limitations of the MLC lead to many constraints on aperture shape, and setup times for apertures make the number of apertures an important factor in overall treatment time. We have developed, implemented and tested on clinical cases a metaheuristic (that is, a method that provides a framework to guide the repeated application of another heuristic) that efficiently generates very high-quality (low aperture number) segmentations. Our computational results demonstrate that the number of beam apertures and monitor units in the treatment plans resulting from our approach is significantly smaller than the corresponding values for treatment plans generated by the heuristics embedded in a widely use commercial system. We also contrast the excellent results of our fast and robust metaheuristic with results from an 'exact' method, branch-and-cut, which attempts to construct optimal solutions, but, within clinically acceptable time limits, generally fails to produce good solutions, especially for intensity maps with more than five intensity levels. Finally, we show that in no instance is there a clinically significant change of quality associated with our more efficient plans.

  15. Acceleration modules in linear induction accelerators

    NASA Astrophysics Data System (ADS)

    Wang, Shao-Heng; Deng, Jian-Jun

    2014-05-01

    The Linear Induction Accelerator (LIA) is a unique type of accelerator that is capable of accelerating kilo-Ampere charged particle current to tens of MeV energy. The present development of LIA in MHz bursting mode and the successful application into a synchrotron have broadened LIA's usage scope. Although the transformer model is widely used to explain the acceleration mechanism of LIAs, it is not appropriate to consider the induction electric field as the field which accelerates charged particles for many modern LIAs. We have examined the transition of the magnetic cores' functions during the LIA acceleration modules' evolution, distinguished transformer type and transmission line type LIA acceleration modules, and re-considered several related issues based on transmission line type LIA acceleration module. This clarified understanding should help in the further development and design of LIA acceleration modules.

  16. Time-resolved dosimetry using a pinpoint ionization chamber as quality assurance for IMRT and VMAT

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Louwe, Robert J. W., E-mail: rob.louwe@ccdbh.org.nz; Satherley, Thomas; Day, Rebecca A.

    Purpose: To develop a method to verify the dose delivery in relation to the individual control points of intensity modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT) using an ionization chamber. In addition to more effective problem solving during patient-specific quality assurance (QA), the aim is to eventually map out the limitations in the treatment chain and enable a targeted improvement of the treatment technique in an efficient way. Methods: Pretreatment verification was carried out for 255 treatment plans that included a broad range of treatment indications in two departments using the equipment of different vendors. In-house developed softwaremore » was used to enable calculation of the dose delivery for the individual beamlets in the treatment planning system (TPS), for data acquisition, and for analysis of the data. The observed deviations were related to various delivery and measurement parameters such as gantry angle, field size, and the position of the detector with respect to the field edge to distinguish between error sources. Results: The average deviation of the integral fraction dose during pretreatment verification of the planning target volume dose was −2.1% ± 2.2% (1 SD), −1.7% ± 1.7% (1 SD), and 0.0% ± 1.3% (1 SD) for IMRT at the Radboud University Medical Center (RUMC), VMAT (RUMC), and VMAT at the Wellington Blood and Cancer Centre, respectively. Verification of the dose to organs at risk gave very similar results but was generally subject to a larger measurement uncertainty due to the position of the detector at a high dose gradient. The observed deviations could be related to limitations of the TPS beam models, attenuation of the treatment couch, as well as measurement errors. The apparent systematic error of about −2% in the average deviation of the integral fraction dose in the RUMC results could be explained by the limitations of the TPS beam model in the calculation of the beam penumbra. Conclusions

  17. SU-F-T-590: Modeling PTV Dose Fall-Off for Cervical Cancer SBRT Treatment Planning Using VMAT and Step-And-Shoot IMRT

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Delgado, A Brito; Cohen, D; Eng, T

    Purpose: Due to the high dose per fraction in SBRT, dose conformity and dose fall-off are critical. In patients with cervical cancer, rapid dose fall-off is particularly important to limit dose to the nearby rectum, small bowel, and bladder. This study compares the target volume dose fall-off for two radiation delivery techniques, fixed-field IMRT & VMAT, using non-coplanar beam geometries. Further comparisons are made between 6 and 10MV photon beam energies. Methods: Eleven (n=11) patients were planned in Pinnacle3 v9.10 with a NovalisTx (HD120 MLC) machine model using 6 and 10 MV photons. The following three techniques were used: (1)more » IMRT (10 non-coplanar beams) (2) Dual, coplanar 360° VMAT arcs (4° spacing), and (3) Triple, non-coplanar VMAT arcs (1 full arc and dual partial arcs). All plans were normalized such that 98% of the PTV received at least 28Gy/4Fx. Dose was calculated using a 2.0mm isotropic dose grid. To assess dose fall-off, twenty concentric 2mm thick rings were created around the PTV. The maximum dose in each ring was recorded and the data was fitted to model dose fall-off. A separate analysis was performed by separating target volumes into small (0–50cc), medium (51–80cc), and large (81–110cc). Results: Triple, non-coplanar VMAT arcs showed the best dose fall-off for all patients evaluated. All fitted regressions had an R{sup 2}≥0.99. At 10mm from the PTV edge, 10 MV VMAT3-arc had an absolute improvement in dose fall-off of 3.8% and 6.9% over IMRT and VMAT2-arc, respectively. At 30mm, 10 MV VMAT3-arc had an absolute improvement of 12.0% and 7.0% over IMRT and VMAT2-arc, respectively. Faster dose fall-off was observed for small volumes as opposed to medium and large ones—9.6% at 20mm. Conclusion: Triple, non-coplanar VMAT arcs offer the sharpest dose fall-off for cervical SBRT plans. This improvement is most pronounced when treating smaller target volumes.« less

  18. TH-E-BRE-05: Analysis of Dosimetric Characteristics in Two Leaf Motion Calculator Algorithms for Sliding Window IMRT

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wu, L; Huang, B; Rowedder, B

    Purpose: The Smart leaf motion calculator (SLMC) in Eclipse treatment planning system is an advanced fluence delivery modeling algorithm as it takes into account fine MLC features including inter-leaf leakage, rounded leaf tips, non-uniform leaf thickness, and the spindle cavity etc. In this study, SLMC and traditional Varian LMC (VLMC) algorithms were investigated, for the first time, in dosimetric characteristics and delivery accuracy of sliding window (SW) IMRT. Methods: The SW IMRT plans of 51 cancer cases were included to evaluate dosimetric characteristics and dose delivery accuracy from leaf motion calculated by SLMC and VLMC, respectively. All plans were deliveredmore » using a Varian TrueBeam Linac. The DVH and MUs of the plans were analyzed. Three patient specific QA tools - independent dose calculation software IMSure, Delta4 phantom, and EPID portal dosimetry were also used to measure the delivered dose distribution. Results: Significant differences in the MUs were observed between the two LMCs (p≤0.001).Gamma analysis shows an excellent agreement between the planned dose distribution calculated by both LMC algorithms and delivered dose distribution measured by three QA tools in all plans at 3%/3 mm, leading to a mean pass rate exceeding 97%. The mean fraction of pixels with gamma < 1 of SLMC is slightly lower than that of VLMC in the IMSure and Delta4 results, but higher in portal dosimetry (the highest spatial resolution), especially in complex cases such as nasopharynx. Conclusion: The study suggests that the two LMCs generates the similar target coverage and sparing patterns of critical structures. However, SLMC is modestly more accurate than VLMC in modeling advanced MLC features, which may lead to a more accurate dose delivery in SW IMRT. Current clinical QA tools might not be specific enough to differentiate the dosimetric discrepancies at the millimeter level calculated by these two LMC algorithms. NIH/NIGMS grant U54 GM104944, Lincy Endowed

  19. SU-E-T-179: Clinical Impact of IMRT Failure Modes at Or Near TG-142 Tolerance Criteria Levels

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Faught, J Tonigan; Balter, P; Johnson, J

    2015-06-15

    Purpose: Quantitatively assess the clinical impact of 11 critical IMRT dose delivery failure modes. Methods: Eleven step-and-shoot IMRT failure modes (FMs) were introduced into twelve Pinnacle v9.8 treatment plans. One standard and one highly modulated plan on the IROC IMRT phantom and ten previous H&N patient treatment plans were used. FMs included physics components covered by basic QA near tolerance criteria levels (TG-142) such as beam energy, MLC positioning, and MLC modeling. Resultant DVHs were compared to those of failure-free plans and the severity of plan degradation was assessed considering PTV coverage and OAR and normal tissue tolerances and usedmore » for FMEA severity scoring. Six of these FMs were physically simulated and phantom irradiations performed. TLD and radiochromic film results are used for comparison to treatment planning studies. Results: Based on treatment planning studies, the largest clinical impact from the phantom cases was induced by 2 mm systematic MLC shift in one bank with the combination of a D95% target under dose near 16% and OAR overdose near 8%. Cord overdoses of 5%–11% occurred with gantry angle, collimator angle, couch angle, MLC leaf end modeling, and MLC transmission and leakage modeling FMs. PTV coverage and/or OAR sparing was compromised in all FMs introduced in phantom plans with the exception of CT number to electron density tables, MU linearity, and MLC tongue-and-groove modeling. Physical measurements did not entirely agree with treatment planning results. For example, symmetry errors resulted in the largest physically measured discrepancies of up to 3% in the PTVs while a maximum of 0.5% deviation was seen in the treatment planning studies. Patient treatment plan study results are under analysis. Conclusion: Even in the simplistic anatomy of the IROC phantom, some basic physics FMs, just outside of TG-142 tolerance criteria, appear to have the potential for large clinical implications.« less

  20. SU-F-T-440: The Feasibility Research of Checking Cervical Cancer IMRT Pre- Treatment Dose Verification by Automated Treatment Planning Verification System

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Liu, X; Yin, Y; Lin, X

    Purpose: To assess the preliminary feasibility of automated treatment planning verification system in cervical cancer IMRT pre-treatment dose verification. Methods: The study selected randomly clinical IMRT treatment planning data for twenty patients with cervical cancer, all IMRT plans were divided into 7 fields to meet the dosimetric goals using a commercial treatment planning system(PianncleVersion 9.2and the EclipseVersion 13.5). The plans were exported to the Mobius 3D (M3D)server percentage differences of volume of a region of interest (ROI) and dose calculation of target region and organ at risk were evaluated, in order to validate the accuracy automated treatment planning verification system.more » Results: The difference of volume for Pinnacle to M3D was less than results for Eclipse to M3D in ROI, the biggest difference was 0.22± 0.69%, 3.5±1.89% for Pinnacle and Eclipse respectively. M3D showed slightly better agreement in dose of target and organ at risk compared with TPS. But after recalculating plans by M3D, dose difference for Pinnacle was less than Eclipse on average, results were within 3%. Conclusion: The method of utilizing the automated treatment planning system to validate the accuracy of plans is convenientbut the scope of differences still need more clinical patient cases to determine. At present, it should be used as a secondary check tool to improve safety in the clinical treatment planning.« less

  1. Application programming in C# environment with recorded user software interactions and its application in autopilot of VMAT/IMRT treatment planning.

    PubMed

    Wang, Henry; Xing, Lei

    2016-11-08

    An autopilot scheme of volumetric-modulated arc therapy (VMAT)/intensity-modulated radiation therapy (IMRT) planning with the guidance of prior knowl-edge is established with recorded interactions between a planner and a commercial treatment planning system (TPS). Microsoft (MS) Visual Studio Coded UI is applied to record some common planner-TPS interactions as subroutines. The TPS used in this study is a Windows-based Eclipse system. The interactions of our application program with Eclipse TPS are realized through a series of subrou-tines obtained by prerecording the mouse clicks or keyboard strokes of a planner in operating the TPS. A strategy to autopilot Eclipse VMAT/IMRT plan selection process is developed as a specific example of the proposed "scripting" method. The autopiloted planning is navigated by a decision function constructed with a reference plan that has the same prescription and similar anatomy with the case at hand. The calculation proceeds by alternating between the Eclipse optimization and the outer-loop optimization independent of the Eclipse. In the C# program, the dosimetric characteristics of a reference treatment plan are used to assess and modify the Eclipse planning parameters and to guide the search for a clinically sensible treatment plan. The approach is applied to plan a head and neck (HN) VMAT case and a prostate IMRT case. Our study demonstrated the feasibility of application programming method in C# environment with recorded interactions of planner-TPS. The process mimics a planner's planning process and automatically provides clinically sensible treatment plans that would otherwise require a large amount of manual trial and error of a planner. The proposed technique enables us to harness a commercial TPS by application programming via the use of recorded human computer interactions and provides an effective tool to greatly facilitate the treatment planning process. © 2016 The Authors.

  2. Application programming in C# environment with recorded user software interactions and its application in autopilot of VMAT/IMRT treatment planning

    PubMed Central

    Wang, Henry

    2016-01-01

    An autopilot scheme of volumetric‐modulated arc therapy (VMAT)/intensity‐modulated radiation therapy (IMRT) planning with the guidance of prior knowledge is established with recorded interactions between a planner and a commercial treatment planning system (TPS). Microsoft (MS) Visual Studio Coded UI is applied to record some common planner‐TPS interactions as subroutines. The TPS used in this study is a Windows‐based Eclipse system. The interactions of our application program with Eclipse TPS are realized through a series of subroutines obtained by prerecording the mouse clicks or keyboard strokes of a planner in operating the TPS. A strategy to autopilot Eclipse VMAT/IMRT plan selection process is developed as a specific example of the proposed “scripting” method. The autopiloted planning is navigated by a decision function constructed with a reference plan that has the same prescription and similar anatomy with the case at hand. The calculation proceeds by alternating between the Eclipse optimization and the outer‐loop optimization independent of the Eclipse. In the C# program, the dosimetric characteristics of a reference treatment plan are used to assess and modify the Eclipse planning parameters and to guide the search for a clinically sensible treatment plan. The approach is applied to plan a head and neck (HN) VMAT case and a prostate IMRT case. Our study demonstrated the feasibility of application programming method in C# environment with recorded interactions of planner‐TPS. The process mimics a planner's planning process and automatically provides clinically sensible treatment plans that would otherwise require a large amount of manual trial and error of a planner. The proposed technique enables us to harness a commercial TPS by application programming via the use of recorded human computer interactions and provides an effective tool to greatly facilitate the treatment planning process. PACS number(s): 87.55.D‐, 87.55.kd, 87.55.de PMID

  3. SU-E-T-417: The Impact of Normal Tissue Constraints On PTV Dose Homogeneity for Intensity Modulated Radiotherapy (IMRT), Volume Modulated Arc Therapy (VMAT) and Tomotherapy

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Peng, J; McDonald, D; Ashenafi, M

    2014-06-01

    Purpose: Complex intensity modulated arc therapy tends to spread low dose to normal tissue(NT)regions to obtain improved target conformity and homogeneity and OAR sparing.This work evaluates the trade-offs between PTV homogeneity and reduction of the maximum dose(Dmax)spread to NT while planning of IMRT,VMAT and Tomotherapy. Methods: Ten prostate patients,previously planned with step-and-shoot IMRT,were selected.To fairly evaluate how PTV homogeneity was affected by NT Dmax constraints,original IMRT DVH objectives for PTV and OARs(femoral heads,and rectal and bladder wall)applied to 2 VMAT plans in Pinnacle(V9.0), and Tomotherapy(V4.2).The only constraint difference was the NT which was defined as body contours excluding targets,OARs andmore » dose rings.NT Dmax constraint for 1st VMAT was set to the prescription dose(Dp).For 2nd VMAT(VMAT-NT)and Tomotherapy,it was set to the Dmax achieved in IMRT(~70-80% of Dp).All NT constraints were set to the lowest priority.Three common homogeneity indices(HI),RTOG-HI=Dmax/Dp,moderated-HI=D95%/D5% and complex-HI=(D2%-D98%)/Dp*100 were calculated. Results: All modalities with similar dosimetric endpoints for PTV and OARs.The complex-HI shows the most variability of indices,with average values of 5.9,4.9,9.3 and 6.1 for IMRT,VMAT,VMAT-NT and Tomotherapy,respectively.VMAT provided the best PTV homogeneity without compromising any OAR/NT sparing.Both VMAT-NT and Tomotherapy,planned with more restrictive NT constraints,showed reduced homogeneity,with VMAT-NT showing the worst homogeneity(P<0.0001)for all HI.Tomotherapy gave the lowest NT Dmax,with slightly decreased homogeneity compared to VMAT. Finally, there was no significant difference in NT Dmax or Dmean between VMAT and VMAT-NT. Conclusion: PTV HI is highly dependent on permitted NT constraints. Results demonstrated that VMAT-NT with more restrictive NT constraints does not reduce Dmax NT,but significantly receives higher Dmax and worse target homogeneity.Therefore, it is

  4. Suppression of dark current radiation in step-and-shoot intensity modulated radiation therapy by the initial pulse-forming network.

    PubMed

    Cheng, Chee-Wai; Das, Indra J; Ndlovu, Alois M

    2002-09-01

    The effect of the initial pulse forming network (IPFN) on the suppression of dark current is investigated for a Siemens Primus accelerator. The dark current produces a spurious radiation, which is referred to as dark current radiation (DCR) in this study. In the step-and-shoot delivery of an intensity modulated radiation therapy (IMRT), the DCR could be of some concern for whole body dose along with leakage radiation through collimator jaws or multileaf collimator. By adjusting the IPFN-to-PFN ratio to >0.8, the DCR can be measured with an ion chamber during the "PAUSE" state of the accelerator in the IMRT mode. For 15 MV x rays, the magnitude of the DCR is approximately equal to 0.7% of the dose at dmax for a 10 x 10 cm2 field. The DCR has a similar central axis depth dose as a 15 MV beam as determined from a water phantom scan. When the IPFN-to-PFN ratio is lowered to <0.8, no DCR is detected. For low energy x rays (6 MV), no DCR is detected regardless of the IPFN-to-PFN ratio. Although the DCR is studied only for the Siemens Primus model accelerator, the same precaution applies to other models of modern accelerators from other vendors. Due to the large number of field segments used in a step-and-shoot IMRT, it is imperative therefore, that dark current evaluation be part of machine commissioning and annual calibration for high-energy photon beams. Should DCR be detected, the medical physicist should work with a service engineer to rectify the problem. In view of DCR and whole body dose, low-energy photon beams are advisable for IMRT.

  5. Xerostomia in patients treated for oropharyngeal carcinoma: comparing linear accelerator-based intensity-modulated radiation therapy with helical tomotherapy.

    PubMed

    Fortin, Israël; Fortin, Bernard; Lambert, Louise; Clavel, Sébastien; Alizadeh, Moein; Filion, Edith J; Soulières, Denis; Bélair, Manon; Guertin, Louis; Nguyen-Tan, Phuc Felix

    2014-09-01

    In comparison to sliding-window intensity-modulated radiation therapy (sw-IMRT), we hypothesized that helical tomotherapy (HT) would achieve similar locoregional control and, at the same time, decrease the parotid gland dose, thus leading to a xerostomia reduction. The association between radiation techniques, mean parotid dose, and xerostomia incidence, was reviewed in 119 patients with advanced oropharyngeal carcinoma treated with concurrent chemoradiation using sw-IMRT (n = 59) or HT (n = 60). Ipsilateral and contralateral parotid mean doses were significantly lower for patients treated with HT versus sw-IMRT: 24 Gy versus 32 Gy ipsilaterally and 20 Gy versus 25 Gy contralaterally. The incidence of grade ≥2 xerostomia was significantly lower in the HT group than in the sw-IMRT group: 12% versus 78% at 6 months, 3% versus 51% at 12 months, and 0% versus 25% at 24 months. Total parotid mean dose <25 Gy was strongly associated to a lower incidence of grade ≥2 xerostomia at 6, 12, and 24 months. This retrospective series suggests that using HT can better spare the parotid glands while respecting quantitative analysis of normal tissue effects in the clinic (QUANTEC)'s criteria. Copyright © 2013 Wiley Periodicals, Inc.

  6. TH-E-BRF-02: 4D-CT Ventilation Image-Based IMRT Plans Are Dosimetrically Comparable to SPECT Ventilation Image-Based Plans

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kida, S; University of Tokyo Hospital, Bunkyo, Tokyo; Bal, M

    Purpose: An emerging lung ventilation imaging method based on 4D-CT can be used in radiotherapy to selectively avoid irradiating highly-functional lung regions, which may reduce pulmonary toxicity. Efforts to validate 4DCT ventilation imaging have been focused on comparison with other imaging modalities including SPECT and xenon CT. The purpose of this study was to compare 4D-CT ventilation image-based functional IMRT plans with SPECT ventilation image-based plans as reference. Methods: 4D-CT and SPECT ventilation scans were acquired for five thoracic cancer patients in an IRB-approved prospective clinical trial. The ventilation images were created by quantitative analysis of regional volume changes (amore » surrogate for ventilation) using deformable image registration of the 4D-CT images. A pair of 4D-CT ventilation and SPECT ventilation image-based IMRT plans was created for each patient. Regional ventilation information was incorporated into lung dose-volume objectives for IMRT optimization by assigning different weights on a voxel-by-voxel basis. The objectives and constraints of the other structures in the plan were kept identical. The differences in the dose-volume metrics have been evaluated and tested by a paired t-test. SPECT ventilation was used to calculate the lung functional dose-volume metrics (i.e., mean dose, V20 and effective dose) for both 4D-CT ventilation image-based and SPECT ventilation image-based plans. Results: Overall there were no statistically significant differences in any dose-volume metrics between the 4D-CT and SPECT ventilation imagebased plans. For example, the average functional mean lung dose of the 4D-CT plans was 26.1±9.15 (Gy), which was comparable to 25.2±8.60 (Gy) of the SPECT plans (p = 0.89). For other critical organs and PTV, nonsignificant differences were found as well. Conclusion: This study has demonstrated that 4D-CT ventilation image-based functional IMRT plans are dosimetrically comparable to SPECT ventilation

  7. Direct-detection EPID dosimetry: investigation of a potential clinical configuration for IMRT verification.

    PubMed

    Vial, Philip; Gustafsson, Helen; Oliver, Lyn; Baldock, Clive; Greer, Peter B

    2009-12-07

    The routine use of electronic portal imaging devices (EPIDs) as dosimeters for radiotherapy quality assurance is complicated by the non-water equivalence of the EPID's dose response. A commercial EPID modified to a direct-detection configuration was previously demonstrated to provide water-equivalent dose response with d(max) solid water build-up and 10 cm solid water backscatter. Clinical implementation of the direct EPID (dEPID) requires a design that maintains the water-equivalent dose response, can be incorporated onto existing EPID support arms and maintains sufficient image quality for clinical imaging. This study investigated the dEPID dose response with different configurations of build-up and backscatter using varying thickness of solid water and copper. Field size output factors and beam profiles measured with the dEPID were compared with ionization chamber measurements of dose in water for both 6 MV and 18 MV. The dEPID configured with d(max) solid water build-up and no backscatter (except for the support arm) was within 1.5% of dose in water data for both energies. The dEPID was maintained in this configuration for clinical dosimetry and image quality studies. Close agreement between the dEPID and treatment planning system was obtained for an IMRT field with 98.4% of pixels within the field meeting a gamma criterion of 3% and 3 mm. The reduced sensitivity of the dEPID resulted in a poorer image quality based on quantitative (contrast-to-noise ratio) and qualitative (anthropomorphic phantom) studies. However, clinically useful images were obtained with the dEPID using typical treatment field doses. The dEPID is a water-equivalent dosimeter that can be implemented with minimal modifications to the standard commercial EPID design. The proposed dEPID design greatly simplifies the verification of IMRT dose delivery.

  8. IMRT for head and neck cancer: reducing xerostomia and dysphagia.

    PubMed

    Wang, XiaoShen; Eisbruch, Avraham

    2016-08-01

    Dysphagia and xerostomia are the main sequellae of chemoradiotherapy for head and neck cancer, and the main factors in reducing long-term patient quality of life. IMRT uses advanced technology to focus the high radiation doses on the targets and avoid irradiation of non-involved tissues. The decisions about sparing organs and tissues whose damage causes xerostomia and dysphagia depends on the evidence for dose-response relationships for the organs causing these sequellae. This paper discusses the evidence for the contribution of radiotherapy to xerostomia via damage of the major salivary glands (parotid and submandibular) and minor salivary glands within the oral cavity, and the contribution of radiotherapy-related effect on important swallowing structures causing dysphagia. Recommendations for dose limits to these organs, based on measurements of xerostomia and dysphagia following radiotherapy, are provided here. © The Author 2016. Published by Oxford University Press on behalf of The Japan Radiation Research Society and Japanese Society for Radiation Oncology.

  9. Development of an iterative reconstruction method to overcome 2D detector low resolution limitations in MLC leaf position error detection for 3D dose verification in IMRT.

    PubMed

    Visser, R; Godart, J; Wauben, D J L; Langendijk, J A; Van't Veld, A A; Korevaar, E W

    2016-05-21

    The objective of this study was to introduce a new iterative method to reconstruct multi leaf collimator (MLC) positions based on low resolution ionization detector array measurements and to evaluate its error detection performance. The iterative reconstruction method consists of a fluence model, a detector model and an optimizer. Expected detector response was calculated using a radiotherapy treatment plan in combination with the fluence model and detector model. MLC leaf positions were reconstructed by minimizing differences between expected and measured detector response. The iterative reconstruction method was evaluated for an Elekta SLi with 10.0 mm MLC leafs in combination with the COMPASS system and the MatriXX Evolution (IBA Dosimetry) detector with a spacing of 7.62 mm. The detector was positioned in such a way that each leaf pair of the MLC was aligned with one row of ionization chambers. Known leaf displacements were introduced in various field geometries ranging from  -10.0 mm to 10.0 mm. Error detection performance was tested for MLC leaf position dependency relative to the detector position, gantry angle dependency, monitor unit dependency, and for ten clinical intensity modulated radiotherapy (IMRT) treatment beams. For one clinical head and neck IMRT treatment beam, influence of the iterative reconstruction method on existing 3D dose reconstruction artifacts was evaluated. The described iterative reconstruction method was capable of individual MLC leaf position reconstruction with millimeter accuracy, independent of the relative detector position within the range of clinically applied MU's for IMRT. Dose reconstruction artifacts in a clinical IMRT treatment beam were considerably reduced as compared to the current dose verification procedure. The iterative reconstruction method allows high accuracy 3D dose verification by including actual MLC leaf positions reconstructed from low resolution 2D measurements.

  10. SU-E-T-581: Planning Evaluation of Step-And-Shoot IMRT, RapidArc and Helical TomoTherapy for Hippocampal-Avoidance Whole Brain Radiotherapy (HA-WBRT).

    PubMed

    Evans, J; Chen, Q; Wuthrick, E; Weldon, M; Rong, Y

    2012-06-01

    Several planning strategies are available for hippocampal- avoidance whole-brain radiotherapy (HA-WBRT) following RTOG protocol 0933, but have yet to be compared on a common set of patient data. In this inter-institutional investigation, we evaluate three modalities likely to be employed by protocol participants; step-and-shoot IMRT, volumetric modulated arc therapy, and helical tomotherapy. A common set of patients is used for comparison, including credentialing and successfully accrued patients. Eight patient datasets were selected and de-identified prior to planning. Structures were contoured by physicians per protocol using fused MRI datasets. Three plans were generated for each dataset: Philips Pinnacle 9-field non-coplanar IMRT using protocol recommended beam parameters, Varian's RapidArc using two coplanar arcs, and Accuray's TomoTherapy using a 1cm jaw width. With the goal of meeting the compliance criteria outlined in RTOG 0933 (target coverage and dose limits to the hippocampus and optic structures), three planners independently planned each modality without prior knowledge of the patient's other plans to reduce bias. The three plans for each patient were compared according to the protocol's dosimetric compliance criteria. A homogeneity index was also computed to compare target dose uniformity. All plans achieved the protocol dose criteria, except for one RapidArc plan with slightly inferior dose to the optic chiasm. TomoTherapy offered superior dose homogeneity for all patients. For the two linac based methods, RapidArc was found to provide dose homogeneity at least as good as, and in most cases superior to, 9-field step-and-shoot IMRT. Helical TomoTherapy offers superior dose homogeneity for HA-WBRT following RTOG 0933. Compared to step-and-shoot IMRT, volumetric modulated arc techniques, such as RapidArc, can offer improved homogeneity for HA- WBRT and are generally more efficient/expeditious to deliver than the noncoplanar 9-field arrangement

  11. Evaluation of the radiobiological gamma index with motion interplay in tangential IMRT breast treatment

    PubMed Central

    Sumida, Iori; Yamaguchi, Hajime; Das, Indra J.; Kizaki, Hisao; Aboshi, Keiko; Tsujii, Mari; Yamada, Yuji; Tamari, Kiesuke; Suzuki, Osamu; Seo, Yuji; Isohashi, Fumiaki; Yoshioka, Yasuo; Ogawa, Kazuhiko

    2016-01-01

    The purpose of this study was to evaluate the impact of the motion interplay effect in early-stage left-sided breast cancer intensity-modulated radiation therapy (IMRT), incorporating the radiobiological gamma index (RGI). The IMRT dosimetry for various breathing amplitudes and cycles was investigated in 10 patients. The predicted dose was calculated using the convolution of segmented measured doses. The physical gamma index (PGI) of the planning target volume (PTV) and the organs at risk (OAR) was calculated by comparing the original with the predicted dose distributions. The RGI was calculated from the PGI using the tumor control probability (TCP) and the normal tissue complication probability (NTCP). The predicted mean dose and the generalized equivalent uniform dose (gEUD) to the target with various breathing amplitudes were lower than the original dose (P < 0.01). The predicted mean dose and gEUD to the OARs with motion were higher than for the original dose to the OARs (P < 0.01). However, the predicted data did not differ significantly between the various breathing cycles for either the PTV or the OARs. The mean RGI gamma passing rate for the PTV was higher than that for the PGI (P < 0.01), and for OARs, the RGI values were higher than those for the PGI (P < 0.01). The gamma passing rates of the RGI for the target and the OARs other than the contralateral lung differed significantly from those of the PGI under organ motion. Provided an NTCP value <0.05 is considered acceptable, it may be possible, by taking breathing motion into consideration, to escalate the dose to achieve the PTV coverage without compromising the TCP. PMID:27534793

  12. Accelerator system and method of accelerating particles

    NASA Technical Reports Server (NTRS)

    Wirz, Richard E. (Inventor)

    2010-01-01

    An accelerator system and method that utilize dust as the primary mass flux for generating thrust are provided. The accelerator system can include an accelerator capable of operating in a self-neutralizing mode and having a discharge chamber and at least one ionizer capable of charging dust particles. The system can also include a dust particle feeder that is capable of introducing the dust particles into the accelerator. By applying a pulsed positive and negative charge voltage to the accelerator, the charged dust particles can be accelerated thereby generating thrust and neutralizing the accelerator system.

  13. SU-F-BRD-13: Quantum Annealing Applied to IMRT Beamlet Intensity Optimization

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Nazareth, D; Spaans, J

    Purpose: We report on the first application of quantum annealing (QA) to the process of beamlet intensity optimization for IMRT. QA is a new technology, which employs novel hardware and software techniques to address various discrete optimization problems in many fields. Methods: We apply the D-Wave Inc. proprietary hardware, which natively exploits quantum mechanical effects for improved optimization. The new QA algorithm, running on this hardware, is most similar to simulated annealing, but relies on natural processes to directly minimize the free energy of a system. A simple quantum system is slowly evolved into a classical system, representing the objectivemore » function. To apply QA to IMRT-type optimization, two prostate cases were considered. A reduced number of beamlets were employed, due to the current QA hardware limitation of ∼500 binary variables. The beamlet dose matrices were computed using CERR, and an objective function was defined based on typical clinical constraints, including dose-volume objectives. The objective function was discretized, and the QA method was compared to two standard optimization Methods: simulated annealing and Tabu search, run on a conventional computing cluster. Results: Based on several runs, the average final objective function value achieved by the QA was 16.9 for the first patient, compared with 10.0 for Tabu and 6.7 for the SA. For the second patient, the values were 70.7 for the QA, 120.0 for Tabu, and 22.9 for the SA. The QA algorithm required 27–38% of the time required by the other two methods. Conclusion: In terms of objective function value, the QA performance was similar to Tabu but less effective than the SA. However, its speed was 3–4 times faster than the other two methods. This initial experiment suggests that QA-based heuristics may offer significant speedup over conventional clinical optimization methods, as quantum annealing hardware scales to larger sizes.« less

  14. Radiation-induced second cancers: the impact of 3D-CRT and IMRT

    NASA Technical Reports Server (NTRS)

    Hall, Eric J.; Wuu, Cheng-Shie

    2003-01-01

    Information concerning radiation-induced malignancies comes from the A-bomb survivors and from medically exposed individuals, including second cancers in radiation therapy patients. The A-bomb survivors show an excess incidence of carcinomas in tissues such as the gastrointestinal tract, breast, thyroid, and bladder, which is linear with dose up to about 2.5 Sv. There is great uncertainty concerning the dose-response relationship for radiation-induced carcinogenesis at higher doses. Some animal and human data suggest a decrease at higher doses, usually attributed to cell killing; other data suggest a plateau in dose. Radiotherapy patients also show an excess incidence of carcinomas, often in sites remote from the treatment fields; in addition there is an excess incidence of sarcomas in the heavily irradiated in-field tissues. The transition from conventional radiotherapy to three-dimensional conformal radiation therapy (3D-CRT) involves a reduction in the volume of normal tissues receiving a high dose, with an increase in dose to the target volume that includes the tumor and a limited amount of normal tissue. One might expect a decrease in the number of sarcomas induced and also (less certain) a small decrease in the number of carcinomas. All around, a good thing. By contrast, the move from 3D-CRT to intensity-modulated radiation therapy (IMRT) involves more fields, and the dose-volume histograms show that, as a consequence, a larger volume of normal tissue is exposed to lower doses. In addition, the number of monitor units is increased by a factor of 2 to 3, increasing the total body exposure, due to leakage radiation. Both factors will tend to increase the risk of second cancers. Altogether, IMRT is likely to almost double the incidence of second malignancies compared with conventional radiotherapy from about 1% to 1.75% for patients surviving 10 years. The numbers may be larger for longer survival (or for younger patients), but the ratio should remain the same.

  15. Evaluation of the respiratory motion influence in the 3D dose distribution of IMRT breast radiation therapy treatments

    NASA Astrophysics Data System (ADS)

    Lizar, J. C.; Santos, L. F.; Brandão, F. C.; Volpato, K. C.; Guimarães, F. S.; Pavoni, J. F.

    2017-05-01

    This study aims to evaluate the motion influence in the tridimensional dose distribution due to respiratory for IMRT breast planning technique. To simulate the breathing movement an oscillating platform was used. To simulate the breast, MAGIC-f phantoms were used. CT images of a static phantom were obtained and the IMRT treatment was planned based on them. One phantom was irradiated static in the platform and two other phantoms were irradiated while oscillating in the platform with amplitudes of 0.34 cm and 1.22 cm, the fourth phantom was used as reference in the MRI acquisition. The percentage of points approved in the 3D global gamma analyses (3%/3mm) when comparing the dose distribution of the static phantom with the oscillating ones was 91% for the 0.34cm amplitude and 62% for the 1.22 cm amplitude. Considering this result, the differences found in the dosimetric analyses for the oscillating amplitude of 0.34cm could be considered acceptable in a real treatment. The isodose distribution analyses showed a decrease of dose in the anterior breast region and an increase of dose on the posterior breast region, being these differences most pronounced for large amplitude motion.

  16. IMRT head and neck treatment planning with a commercially available Monte Carlo based planning system

    NASA Astrophysics Data System (ADS)

    Boudreau, C.; Heath, E.; Seuntjens, J.; Ballivy, O.; Parker, W.

    2005-03-01

    The PEREGRINE Monte Carlo dose-calculation system (North American Scientific, Cranberry Township, PA) is the first commercially available Monte Carlo dose-calculation code intended specifically for intensity modulated radiotherapy (IMRT) treatment planning and quality assurance. In order to assess the impact of Monte Carlo based dose calculations for IMRT clinical cases, dose distributions for 11 head and neck patients were evaluated using both PEREGRINE and the CORVUS (North American Scientific, Cranberry Township, PA) finite size pencil beam (FSPB) algorithm with equivalent path-length (EPL) inhomogeneity correction. For the target volumes, PEREGRINE calculations predict, on average, a less than 2% difference in the calculated mean and maximum doses to the gross tumour volume (GTV) and clinical target volume (CTV). An average 16% ± 4% and 12% ± 2% reduction in the volume covered by the prescription isodose line was observed for the GTV and CTV, respectively. Overall, no significant differences were noted in the doses to the mandible and spinal cord. For the parotid glands, PEREGRINE predicted a 6% ± 1% increase in the volume of tissue receiving a dose greater than 25 Gy and an increase of 4% ± 1% in the mean dose. Similar results were noted for the brainstem where PEREGRINE predicted a 6% ± 2% increase in the mean dose. The observed differences between the PEREGRINE and CORVUS calculated dose distributions are attributed to secondary electron fluence perturbations, which are not modelled by the EPL correction, issues of organ outlining, particularly in the vicinity of air cavities, and differences in dose reporting (dose to water versus dose to tissue type).

  17. SU-E-T-454: Impact of Calculation Grid Size On Dosimetry and Radiobiological Parameters for Head and Neck IMRT

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Srivastava, S; Das, I; Indiana University Health Methodist Hospital, Indianapolis, IN

    2014-06-01

    Purpose: IMRT has become standard of care for complex treatments to optimize dose to target and spare normal tissues. However, the impact of calculation grid size is not widely known especially dose distribution, tumor control probability (TCP) and normal tissue complication probability (NTCP) which is investigated in this study. Methods: Ten head and neck IMRT patients treated with 6 MV photons were chosen for this study. Using Eclipse TPS, treatment plans were generated for different grid sizes in the range 1–5 mm for the same optimization criterion with specific dose-volume constraints. The dose volume histogram (DVH) was calculated for allmore » IMRT plans and dosimetric data were compared. ICRU-83 dose points such as D2%, D50%, D98%, as well as the homogeneity and conformity indices (HI, CI) were calculated. In addition, TCP and NTCP were calculated from DVH data. Results: The PTV mean dose and TCP decreases with increasing grid size with an average decrease in mean dose by 2% and TCP by 3% respectively. Increasing grid size from 1–5 mm grid size, the average mean dose and NTCP for left parotid was increased by 6.0% and 8.0% respectively. Similar patterns were observed for other OARs such as cochlea, parotids and spinal cord. The HI increases up to 60% and CI decreases on average by 3.5% between 1 and 5 mm grid that resulted in decreased TCP and increased NTCP values. The number of points meeting the gamma criteria of ±3% dose difference and ±3mm DTA was higher with a 1 mm on average (97.2%) than with a 5 mm grid (91.3%). Conclusion: A smaller calculation grid provides superior dosimetry with improved TCP and reduced NTCP values. The effect is more pronounced for smaller OARs. Thus, the smallest possible grid size should be used for accurate dose calculation especially in H and N planning.« less

  18. Out-of-field doses from pediatric craniospinal irradiations using 3D-CRT, IMRT, helical tomotherapy and electron-based therapy

    NASA Astrophysics Data System (ADS)

    De Saint-Hubert, Marijke; Verellen, Dirk; Poels, Kenneth; Crijns, Wouter; Magliona, Federica; Depuydt, Tom; Vanhavere, Filip; Struelens, Lara

    2017-07-01

    Medulloblastoma treatment involves irradiation of the entire central nervous system, i.e. craniospinal irradiation (CSI). This is associated with the significant exposure of large volumes of healthy tissue and there is growing concern regarding treatment-associated side effects. The current study compares out-of-field organ doses in children receiving CSI through 3D-conformal radiotherapy (3D-CRT), intensity modulated radiotherapy (IMRT), helical tomotherapy (HT) and an electron-based technique, and includes radiation doses resulting from imaging performed during treatment. An extensive phantom study is performed, using an anthropomorphic phantom corresponding to a five year old child, in which organ absorbed doses are measured using thermoluminescent detectors. Additionally, the study evaluates and explores tools for calculating out-of-field patient doses using the treatment planning system (TPS) and analytical models. In our study, 3D-CRT resulted in very high doses to a limited number of organs, while it was able to spare organs such as the lungs and breast when compared to IMRT and HT. Both IMRT and HT spread the dose over more organs and were able to spare the heart, thyroid, bladder, uterus and testes when compared to 3D-CRT. The electron-based technique considerably decreased the out-of-field doses in deep-seated organs but could not avoid nearby out-of-field organs such as the lungs, ribs, adrenals, kidneys and uterus. The daily imaging dose is small compared to the treatment dose burden. The TPS error for out-of-field doses was most pronounced for organs further away from the target; nevertheless, no systematic underestimation was observed for any of the studied TPS systems. Finally, analytical modeling was most optimal for 3D-CRT although the number of organs that could be modeled was limited. To conclude, none of the techniques studied was capable of sparing all organs from out-of-field doses. Nevertheless, the electron-based technique showed the most

  19. Intra-cavitary dosimetry for IMRT head and neck treatment using thermoluminescent dosimeters in a naso-oesophageal tube.

    PubMed

    Gagliardi, F M; Roxby, K J; Engström, P E; Crosbie, J C

    2009-06-21

    Complex intensity-modulated radiation therapy (IMRT) treatment plans require rigorous quality assurance tests. The aim of this study was to independently verify the delivered dose inside the patient in the region of the treatment site. A flexible naso-gastric tube containing thermoluminescent dosimeters (TLDs) was inserted into the oesophagus via the sinus cavity before the patient's first treatment. Lead markers were also inserted into the tube in order that the TLD positions could be accurately determined from the lateral and anterior-posterior electronic portal images taken prior to treatment. The measured dose was corrected for both daily linac output variations and the estimated dose received from the portal images. The predicted dose for each TLD was determined from the treatment planning system and compared to the measured TLD doses. The results comprise 431 TLD measurements on 43 patients. The mean measured-to-predicted dose ratio was 0.988 +/- 0.011 (95% confidence interval) for measured doses above 0.2 Gy. There was a variation in this ratio when the measurements were separated into low dose (0.2-1.0 Gy), medium dose (1.0-1.8 Gy) and high dose (>1.8 Gy) measurements. The TLD-loaded, naso-oesophageal tube for in vivo dose verification is straightforward to implement, and well tolerated by patients. It provides independent reassurance of the delivered dose for head and neck IMRT.

  20. Intra-cavitary dosimetry for IMRT head and neck treatment using thermoluminescent dosimeters in a naso-oesophageal tube

    NASA Astrophysics Data System (ADS)

    Gagliardi, F. M.; Roxby, K. J.; Engström, P. E.; Crosbie, J. C.

    2009-06-01

    Complex intensity-modulated radiation therapy (IMRT) treatment plans require rigorous quality assurance tests. The aim of this study was to independently verify the delivered dose inside the patient in the region of the treatment site. A flexible naso-gastric tube containing thermoluminescent dosimeters (TLDs) was inserted into the oesophagus via the sinus cavity before the patient's first treatment. Lead markers were also inserted into the tube in order that the TLD positions could be accurately determined from the lateral and anterior-posterior electronic portal images taken prior to treatment. The measured dose was corrected for both daily linac output variations and the estimated dose received from the portal images. The predicted dose for each TLD was determined from the treatment planning system and compared to the measured TLD doses. The results comprise 431 TLD measurements on 43 patients. The mean measured-to-predicted dose ratio was 0.988 ± 0.011 (95% confidence interval) for measured doses above 0.2 Gy. There was a variation in this ratio when the measurements were separated into low dose (0.2-1.0 Gy), medium dose (1.0-1.8 Gy) and high dose (>1.8 Gy) measurements. The TLD-loaded, naso-oesophageal tube for in vivo dose verification is straightforward to implement, and well tolerated by patients. It provides independent reassurance of the delivered dose for head and neck IMRT.

  1. Comparison of IMRT planning with two-step and one-step optimization: a strategy for improving therapeutic gain and reducing the integral dose

    NASA Astrophysics Data System (ADS)

    Abate, A.; Pressello, M. C.; Benassi, M.; Strigari, L.

    2009-12-01

    The aim of this study was to evaluate the effectiveness and efficiency in inverse IMRT planning of one-step optimization with the step-and-shoot (SS) technique as compared to traditional two-step optimization using the sliding windows (SW) technique. The Pinnacle IMRT TPS allows both one-step and two-step approaches. The same beam setup for five head-and-neck tumor patients and dose-volume constraints were applied for all optimization methods. Two-step plans were produced converting the ideal fluence with or without a smoothing filter into the SW sequence. One-step plans, based on direct machine parameter optimization (DMPO), had the maximum number of segments per beam set at 8, 10, 12, producing a directly deliverable sequence. Moreover, the plans were generated whether a split-beam was used or not. Total monitor units (MUs), overall treatment time, cost function and dose-volume histograms (DVHs) were estimated for each plan. PTV conformality and homogeneity indexes and normal tissue complication probability (NTCP) that are the basis for improving therapeutic gain, as well as non-tumor integral dose (NTID), were evaluated. A two-sided t-test was used to compare quantitative variables. All plans showed similar target coverage. Compared to two-step SW optimization, the DMPO-SS plans resulted in lower MUs (20%), NTID (4%) as well as NTCP values. Differences of about 15-20% in the treatment delivery time were registered. DMPO generates less complex plans with identical PTV coverage, providing lower NTCP and NTID, which is expected to reduce the risk of secondary cancer. It is an effective and efficient method and, if available, it should be favored over the two-step IMRT planning.

  2. Co-registration of cone beam CT and planning CT in head and neck IMRT dose estimation: a feasible adaptive radiotherapy strategy

    PubMed Central

    Yip, C; Thomas, C; Michaelidou, A; James, D; Lynn, R; Lei, M

    2014-01-01

    Objective: To investigate if cone beam CT (CBCT) can be used to estimate the delivered dose in head and neck intensity-modulated radiotherapy (IMRT). Methods: 15 patients (10 without replan and 5 with replan) were identified retrospectively. Weekly CBCT was co-registered with original planning CT. Original high-dose clinical target volume (CTV1), low-dose CTV (CTV2), brainstem, spinal cord, parotids and external body contours were copied to each CBCT and modified to account for anatomical changes. Corresponding planning target volumes (PTVs) and planning organ-at-risk volumes were created. The original plan was applied and calculated using modified per-treatment volumes on the original CT. Percentage volumetric, cumulative (planned dose delivered prior to CBCT + adaptive dose delivered after CBCT) and actual delivered (summation of weekly adaptive doses) dosimetric differences between each per-treatment and original plan were calculated. Results: There was greater volumetric change in the parotids with an average weekly difference of between −4.1% and −27.0% compared with the CTVs/PTVs (−1.8% to −5.0%). The average weekly cumulative dosimetric differences were as follows: CTV/PTV (range, −3.0% to 2.2%), ipsilateral parotid volume receiving ≥26 Gy (V26) (range, 0.5–3.2%) and contralateral V26 (range, 1.9–6.3%). In patients who required replan, the average volumetric reductions were greater: CTV1 (−2.5%), CTV2 (−6.9%), PTV1 (−4.7%), PTV2 (−11.5%), ipsilateral (−10.4%) and contralateral parotids (−12.1%), but did not result in significant dosimetric changes. Conclusion: The dosimetric changes during head and neck simultaneous integrated boost IMRT do not necessitate adaptive radiotherapy in most patients. Advances in knowledge: Our study shows that CBCT could be used for dose estimation during head and neck IMRT. PMID:24288402

  3. SU-F-T-306: Validation of Mobius 3D and FX for Elekta Linear Accelerators

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Nelson, C; Garcia, M; Calderon, E

    2016-06-15

    Purpose: Log file based IMRT and VMAT QA is a system that analyzes treatment log files and uses delivery parameters to compute the dose to the patient/phantom. This system was previously commissioned for Varian machines, the purpose of this work is to describe the process for commissioning Mobius for use with Elekta machines. Methods: Twelve IMRT and VMAT plans (6×) were planned and delivered and dose was measured using MapCheck, the results were compared to that computed by Mobius. For 10x and 18x, plans were generated, copied to a phantom and delivered, the dose was measured using a single ionmore » chamber. The difference in measured dose to computed dose (Mobius) was used to adjust the dynamic leaf gap (DLG) in Mobius to achieve optimal agreement between measurements, Mobius and treatment plans. Results: For the measured dose comparison, the average 3%/3mm gamma 97.1% of pixels passed criteria using MapCheck where Mobius computed 96.9% of voxels passing. For 10×, a DLG of −5.5 was determined to achieve optimal results for TPS and measured ion chamber data with an average 0.1% difference and −1.7% respectively. For 18×, a DLG of −3 was determined to achieve optimal results from the TPS and measured data with an average of −0.7% and −1.4% difference on average from a set of IMRT and VMAT plans. The 6x data needed no DLG correction to arrive at agreement with the TPS and the MapCheck measured data. Conclusion: We have validated with measurements for IMRT and VMAT cases the use of Mobius FX with Elekta treatment machines for IMRT and VMAT QA. For 6×, no adjustments to the DLG were required to obtain good results utilizing Mobius whereas for 10× and 18×, the DLG had to be adjusted to obtain optimum agreement with measured data and our TPS.« less

  4. Comparison of chronic toxicities between brachytherapy-based accelerated partial breast irradiation and whole breast irradiation using intensity modulated radiotherapy.

    PubMed

    Wobb, Jessica L; Shah, Chirag; Jawad, Maha S; Wallace, Michelle; Dilworth, Joshua T; Grills, Inga S; Ye, Hong; Chen, Peter Y

    2015-12-01

    Brachytherapy-based APBI (bAPBI) shortens treatment duration and limits dose to normal tissue. While studies have demonstrated similar local control when comparing bAPBI and whole breast irradiation using intensity modulated radiotherapy (WBI-IMRT), comparison of late side effects is limited. Here, we report chronic toxicity profiles associated with these two treatment modalities. 1034 patients with early stage breast cancer were treated at a single institution; 489 received standard-fractionation WBI-IMRT between 2000 and 2013 and 545 received bAPBI (interstitial 40%, applicator-based 60%) between 1993 and 2013. Chronic toxicity was evaluated ≥6 months utilizing CTCAE version 3.0; cosmesis was evaluated using the Harvard scale. Median follow-up was 4.6 years (range 0.1-13.4) for WBI-IMRT versus 6.7 years (range 0.1-20.1) for bAPBI (p < 0.001). Compared to WBI-IMRT, bAPBI was associated with higher rates of ≥grade 2 seroma formation (14.4% vs 2.9%, p < 0.001), telangiectasia (12.3% vs 2.1%, p = 0.002) and symptomatic fat necrosis (10.2% vs 3.6%, p < 0.001). Lower rates of hyperpigmentation were observed (5.8% vs 14.5%; p = 0.001). Infection rates were similar (3.3% vs 1.3%, p = 0.07). There was no difference between rates of fair (6.1% vs. 4.1%, p = 0.30) or poor (0.2% vs. 0.5%, p = NS) cosmesis. Mastectomy rates for local recurrence (3.1% for WBI-IMRT and 1.2% for bAPBI, p = 0.06), or for other reasons (0.8% and 0.6%, p = 0.60) were similar between groups. With 5-year follow-up, WBI-IMRT and bAPBI are associated with similar, acceptable rates of toxicity. These data further support the utilization of bAPBI as a modality to deliver adjuvant radiation in a safe and efficacious manner. Copyright © 2015 Elsevier Ltd. All rights reserved.

  5. Modelling carcinogenesis after radiotherapy using Poisson statistics: implications for IMRT, protons and ions.

    PubMed

    Jones, Bleddyn

    2009-06-01

    Current technical radiotherapy advances aim to (a) better conform the dose contours to cancers and (b) reduce the integral dose exposure and thereby minimise unnecessary dose exposure to normal tissues unaffected by the cancer. Various types of conformal and intensity modulated radiotherapy (IMRT) using x-rays can achieve (a) while charged particle therapy (CPT)-using proton and ion beams-can achieve both (a) and (b), but at greater financial cost. Not only is the long term risk of radiation related normal tissue complications important, but so is the risk of carcinogenesis. Physical dose distribution plans can be generated to show the differences between the above techniques. IMRT is associated with a dose bath of low to medium dose due to fluence transfer: dose is effectively transferred from designated organs at risk to other areas; thus dose and risk are transferred. Many clinicians are concerned that there may be additional carcinogenesis many years after IMRT. CPT reduces the total energy deposition in the body and offers many potential advantages in terms of the prospects for better quality of life along with cancer cure. With C ions there is a tail of dose beyond the Bragg peaks, due to nuclear fragmentation; this is not found with protons. CPT generally uses higher linear energy transfer (which varies with particle and energy), which carries a higher relative risk of malignant induction, but also of cell death quantified by the relative biological effect concept, so at higher dose levels the frank development of malignancy should be reduced. Standard linear radioprotection models have been used to show a reduction in carcinogenesis risk of between two- and 15-fold depending on the CPT location. But the standard risk models make no allowance for fractionation and some have a dose limit at 4 Gy. Alternatively, tentative application of the linear quadratic model and Poissonian statistics to chromosome breakage and cell kill simultaneously allows estimation of

  6. TH-A-BRC-03: AAPM TG218: Measurement Methods and Tolerance Levels for Patient-Specific IMRT Verification QA

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Miften, M.

    2016-06-15

    outline of possible dosimetry protocols. The report will be reviewed by the AAPM Working Group on Recommendations for Radiotherapy External Beam Quality Assurance and then by the AAPM Science Council before publication in Medical Physics Survey of possible calibration protocols for calibration of Gamma Stereotactic Radiosurgery (GSR) devices Overview of modern Quality Assurance techniques for GSR AAPM TG-218 Tolerance Levels and Methodologies for IMRT Verification QA - Moyed Miften Patient-specific IMRT QA measurement is a process designed to identify discrepancies between calculated and delivered doses. Error tolerance limits are not well-defined or consistently applied across centers. The AAPM TG-218 report has been prepared to improve the understanding and consistency of this process by providing recommendations for methodologies and tolerance limits in patient-specific IMRT QA. Learning Objectives: Review measurement methods and methodologies for absolute dose verification Provide recommendations on delivery methods, data interpretation, the use of analysis routines and choice of tolerance limits for IMRT QA Sonja Dieterich has a research agreement with Sun Nuclear Inc. Steven Goetsch is a part-time consultant for Elekta.« less

  7. SU-F-J-64: Comparison of Dosimetric Robustness Between Proton Therapy and IMRT Plans Following Tumor Regression for Locally Advanced Non-Small Cell Lung Cancer (NSCLC)

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Teng, C; Ainsley, C; Teo, B

    Purpose: In the light of tumor regression and normal tissue changes, dose distributions can deviate undesirably from what was planned. As a consequence, replanning is sometimes necessary during treatment to ensure continued tumor coverage or to avoid overdosing organs at risk (OARs). Proton plans are generally thought to be less robust than photon plans because of the proton beam’s higher sensitivity to changes in tissue composition, suggesting also a higher likely replanning rate due to tumor regression. The purpose of this study is to compare dosimetric deviations between forward-calculated double scattering (DS) proton plans with IMRT plans upon tumor regression,more » and assesses their impact on clinical replanning decisions. Methods: Ten consecutive locally advanced NSCLC patients whose tumors shrank > 50% in volume and who received four or more CT scans during radiotherapy were analyzed. All the patients received proton radiotherapy (6660 cGy, 180 cGy/fx). Dosimetric robustness during therapy was characterized by changes in the planning objective metrics as well as by point-by-point root-mean-squared differences for the entire PTV, ITV, and OARs (heart, cord, esophagus, brachial plexus and lungs) DVHs. Results: Sixty-four pairs of DVHs were reviewed by three clinicians, who requested a replanning rate of 16.7% and 18.6% for DS and IMRT plans, respectively, with a high agreement between providers. Robustness of clinical indicators was found to depend on the beam orientation and dose level on the DVH curve. Proton dose increased most in OARs distal to the PTV along the beam path, but these changes were primarily in the mid to low dose levels. In contrast, the variation in IMRT plans occurred primarily in the high dose region. Conclusion: Robustness of clinical indicators depends where on the DVH curves comparisons are made. Similar replanning rates were observed for DS and IMRT plans upon large tumor regression.« less

  8. Early Clinical Outcomes Demonstrate Preserved Cognitive Function in Children With Average-Risk Medulloblastoma When Treated With Hyperfractionated Radiation Therapy

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Gupta, Tejpal, E-mail: tejpalgupta@rediffmail.com; Jalali, Rakesh; Goswami, Savita

    Purpose: To report on acute toxicity, longitudinal cognitive function, and early clinical outcomes in children with average-risk medulloblastoma. Methods and Materials: Twenty children {>=}5 years of age classified as having average-risk medulloblastoma were accrued on a prospective protocol of hyperfractionated radiation therapy (HFRT) alone. Radiotherapy was delivered with two daily fractions (1 Gy/fraction, 6 to 8 hours apart, 5 days/week), initially to the neuraxis (36 Gy/36 fractions), followed by conformal tumor bed boost (32 Gy/32 fractions) for a total tumor bed dose of 68 Gy/68 fractions over 6 to 7 weeks. Cognitive function was prospectively assessed longitudinally (pretreatment and atmore » specified posttreatment follow-up visits) with the Wechsler Intelligence Scale for Children to give verbal quotient, performance quotient, and full-scale intelligence quotient (FSIQ). Results: The median age of the study cohort was 8 years (range, 5-14 years), representing a slightly older cohort. Acute hematologic toxicity was mild and self-limiting. Eight (40%) children had subnormal intelligence (FSIQ <85), including 3 (15%) with mild mental retardation (FSIQ 56-70) even before radiotherapy. Cognitive functioning for all tested domains was preserved in children evaluable at 3 months, 1 year, and 2 years after completion of HFRT, with no significant decline over time. Age at diagnosis or baseline FSIQ did not have a significant impact on longitudinal cognitive function. At a median follow-up time of 33 months (range, 16-58 months), 3 patients had died (2 of relapse and 1 of accidental burns), resulting in 3-year relapse-free survival and overall survival of 83.5% and 83.2%, respectively. Conclusion: HFRT without upfront chemotherapy has an acceptable acute toxicity profile, without an unduly increased risk of relapse, with preserved cognitive functioning in children with average-risk medulloblastoma.« less

  9. Monitoring Dosimetric Impact of Weight Loss With Kilovoltage (KV) Cone Beam CT (CBCT) During Parotid-Sparing IMRT and Concurrent Chemotherapy

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ho, Kean Fatt, E-mail: hokeanfatt@hotmail.com; Marchant, Tom; Moore, Chris

    2012-03-01

    Purpose: Parotid-sparing head-and-neck intensity-modulated radiotherapy (IMRT) can reduce long-term xerostomia. However, patients frequently experience weight loss and tumor shrinkage during treatment. We evaluate the use of kilovoltage (kV) cone beam computed tomography (CBCT) for dose monitoring and examine if the dosimetric impact of such changes on the parotid and critical neural structures warrants replanning during treatment. Methods and materials: Ten patients with locally advanced oropharyngeal cancer were treated with contralateral parotid-sparing IMRT concurrently with platinum-based chemotherapy. Mean doses of 65 Gy and 54 Gy were delivered to clinical target volume (CTV)1 and CTV2, respectively, in 30 daily fractions. CBCT wasmore » prospectively acquired weekly. Each CBCT was coregistered with the planned isocenter. The spinal cord, brainstem, parotids, larynx, and oral cavity were outlined on each CBCT. Dose distributions were recalculated on the CBCT after correcting the gray scale to provide accurate Hounsfield calibration, using the original IMRT plan configuration. Results: Planned contralateral parotid mean doses were not significantly different to those delivered during treatment (p > 0.1). Ipsilateral and contralateral parotids showed a mean reduction in volume of 29.7% and 28.4%, respectively. There was no significant difference between planned and delivered maximum dose to the brainstem (p = 0.6) or spinal cord (p = 0.2), mean dose to larynx (p = 0.5) and oral cavity (p = 0.8). End-of-treatment mean weight loss was 7.5 kg (8.8% of baseline weight). Despite a {>=}10% weight loss in 5 patients, there was no significant dosimetric change affecting the contralateral parotid and neural structures. Conclusions: Although patient weight loss and parotid volume shrinkage was observed, overall, there was no significant excess dose to the organs at risk. No replanning was felt necessary for this patient cohort, but a larger patient sample will be

  10. Automating linear accelerator quality assurance.

    PubMed

    Eckhause, Tobias; Al-Hallaq, Hania; Ritter, Timothy; DeMarco, John; Farrey, Karl; Pawlicki, Todd; Kim, Gwe-Ya; Popple, Richard; Sharma, Vijeshwar; Perez, Mario; Park, SungYong; Booth, Jeremy T; Thorwarth, Ryan; Moran, Jean M

    2015-10-01

    The purpose of this study was 2-fold. One purpose was to develop an automated, streamlined quality assurance (QA) program for use by multiple centers. The second purpose was to evaluate machine performance over time for multiple centers using linear accelerator (Linac) log files and electronic portal images. The authors sought to evaluate variations in Linac performance to establish as a reference for other centers. The authors developed analytical software tools for a QA program using both log files and electronic portal imaging device (EPID) measurements. The first tool is a general analysis tool which can read and visually represent data in the log file. This tool, which can be used to automatically analyze patient treatment or QA log files, examines the files for Linac deviations which exceed thresholds. The second set of tools consists of a test suite of QA fields, a standard phantom, and software to collect information from the log files on deviations from the expected values. The test suite was designed to focus on the mechanical tests of the Linac to include jaw, MLC, and collimator positions during static, IMRT, and volumetric modulated arc therapy delivery. A consortium of eight institutions delivered the test suite at monthly or weekly intervals on each Linac using a standard phantom. The behavior of various components was analyzed for eight TrueBeam Linacs. For the EPID and trajectory log file analysis, all observed deviations which exceeded established thresholds for Linac behavior resulted in a beam hold off. In the absence of an interlock-triggering event, the maximum observed log file deviations between the expected and actual component positions (such as MLC leaves) varied from less than 1% to 26% of published tolerance thresholds. The maximum and standard deviations of the variations due to gantry sag, collimator angle, jaw position, and MLC positions are presented. Gantry sag among Linacs was 0.336 ± 0.072 mm. The standard deviation in MLC

  11. Relevant reduction effect with a modified thermoplastic mask of rotational error for glottic cancer in IMRT

    NASA Astrophysics Data System (ADS)

    Jung, Jae Hong; Jung, Joo-Young; Cho, Kwang Hwan; Ryu, Mi Ryeong; Bae, Sun Hyun; Moon, Seong Kwon; Kim, Yong Ho; Choe, Bo-Young; Suh, Tae Suk

    2017-02-01

    The purpose of this study was to analyze the glottis rotational error (GRE) by using a thermoplastic mask for patients with the glottic cancer undergoing intensity-modulated radiation therapy (IMRT). We selected 20 patients with glottic cancer who had received IMRT by using the tomotherapy. The image modalities with both kilovoltage computed tomography (planning kVCT) and megavoltage CT (daily MVCT) images were used for evaluating the error. Six anatomical landmarks in the image were defined to evaluate a correlation between the absolute GRE (°) and the length of contact with the underlying skin of the patient by the mask (mask, mm). We also statistically analyzed the results by using the Pearson's correlation coefficient and a linear regression analysis ( P <0.05). The mask and the absolute GRE were verified to have a statistical correlation ( P < 0.01). We found a statistical significance for each parameter in the linear regression analysis (mask versus absolute roll: P = 0.004 [ P < 0.05]; mask versus 3D-error: P = 0.000 [ P < 0.05]). The range of the 3D-errors with contact by the mask was from 1.2% - 39.7% between the maximumand no-contact case in this study. A thermoplastic mask with a tight, increased contact area may possibly contribute to the uncertainty of the reproducibility as a variation of the absolute GRE. Thus, we suggest that a modified mask, such as one that covers only the glottis area, can significantly reduce the patients' setup errors during the treatment.

  12. Poster - 53: Improving inter-linac DMLC IMRT dose precision by fine tuning of MLC leaf calibration

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Nakonechny, Keith; Tran, Muoi; Sasaki, David

    Purpose: To develop a method to improve the inter-linac precision of DMLC IMRT dosimetry. Methods: The distance between opposing MLC leaf banks (“gap size”) can be finely tuned on Varian linacs. The dosimetric effect due to small deviations from the nominal gap size (“gap error”) was studied by introducing known errors for several DMLC sliding gap sizes, and for clinical plans based on the TG119 test cases. The plans were delivered on a single Varian linac and the relationship between gap error and the corresponding change in dose was measured. The plans were also delivered on eight Varian 2100 seriesmore » linacs (at two institutions) in order to quantify the inter-linac variation in dose before and after fine tuning the MLC calibration. Results: The measured dose differences for each field agreed well with the predictions of LoSasso et al. Using the default MLC calibration, the variation in the physical MLC gap size was determined to be less than 0.4 mm between all linacs studied. The dose difference between the linacs with the largest and smallest physical gap was up to 5.4% (spinal cord region of the head and neck TG119 test case). This difference was reduced to 2.5% after fine tuning the MLC gap calibration. Conclusions: The inter-linac dose precision for DMLC IMRT on Varian linacs can be improved using a simple modification of the MLC calibration procedure that involves fine adjustment of the nominal gap size.« less

  13. Implementation of IMRT and VMAT using Delta4 phantom and portal dosimetry as dosimetry verification tools

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Daci, Lulzime, E-mail: lulzime.daci@nodlandssykehuset.no; Malkaj, Partizan, E-mail: malkaj-p@hotmail.com

    2016-03-25

    In this study we analyzed and compared the dose distribution of different IMRT and VMAT plans with the intent to provide pre-treatment quality assurance using two different tools. Materials/Methods: We have used the electronic portal imaging device EPID after calibration to dose and correction for the background offset signal and also the Delta4 phantom after en evaluation of angular sensitivity. The Delta4 phantom has a two-dimensional array with ionization chambers. We analyzed three plans for each anatomical site calculated by Eclipse treatment planning system. The measurements were analyzed using γ-evaluation method with passing criteria 3% absolute dose and 3 mm distancemore » to agreement (DTA). For all the plans the range of score has been from 97% to 99% for gantry fixed at 0° while for rotational planes there was a slightly decreased pass rates and above 95%. Point measurement with a ionization chamber were done in additional to see the accuracy of portal dosimetry and to evaluate the Delta4 device to various dose rates. Conclusions: Both Delt4 and Portal dosimetry shows good results between the measured and calculated doses. While Delta4 is more accurate in measurements EPID is more time efficient. We have decided to use both methods in the first steps of IMRT and VMAT implementation and later on to decide which of the tools to use depending on the complexity of plans, how much accurate we want to be and the time we have on the machine.« less

  14. SU-E-T-133: Assessing IMRT Treatment Delivery Accuracy and Consistency On a Varian TrueBeam Using the SunNuclear PerFraction EPID Dosimetry Software

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Dieterich, S; Trestrail, E; Holt, R

    2015-06-15

    Purpose: To assess if the TrueBeam HD120 collimator is delivering small IMRT fields accurately and consistently throughout the course of treatment using the SunNuclear PerFraction software. Methods: 7-field IMRT plans for 8 canine patients who passed IMRT QA using SunNuclear Mapcheck DQA were selected for this study. The animals were setup using CBCT image guidance. The EPID fluence maps were captured for each treatment field and each treatment fraction, with the first fraction EPID data serving as the baseline for comparison. The Sun Nuclear PerFraction Software was used to compare the EPID data for subsequent fractions using a Gamma (3%/3mm)more » pass rate of 90%. To simulate requirements for SRS, the data was reanalyzed using a Gamma (3%/1mm) pass rate of 90%. Low-dose, low- and high gradient thresholds were used to focus the analysis on clinically relevant parts of the dose distribution. Results: Not all fractions could be analyzed, because during some of the treatment courses the DICOM tags in the EPID images intermittently change from CU to US (unspecified), which would indicate a temporary loss of EPID calibration. This technical issue is still being investigated. For the remaining fractions, the vast majority (7/8 of patients, 95% of fractions, and 96.6% of fields) are passing the less stringent Gamma criteria. The more stringent Gamma criteria caused a drop in pass rate (90 % of fractions, 84% of fields). For the patient with the lowest pass rate, wet towel bolus was used. Another patient with low pass rates experienced masseter muscle wasting. Conclusion: EPID dosimetry using the PerFraction software demonstrated that the majority of fields passed a Gamma (3%/3mm) for IMRT treatments delivered with a TrueBeam HD120 MLC. Pass rates dropped for a DTA of 1mm to model SRS tolerances. PerFraction pass rates can flag missing bolus or internal shields. Sanjeev Saini is an employee of Sun Nuclear Corporation. For this study, a pre-release version of Per

  15. SU-E-T-580: Comparison of Cervical Carcinoma IMRT Plans From Four Commercial Treatment Planning Systems (TPS)

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Cao, Y; Li, R; Chi, Z

    2014-06-01

    Purpose: Different treatment planning systems (TPS) use different treatment optimization and leaf sequencing algorithms. This work compares cervical carcinoma IMRT plans optimized with four commercial TPSs to investigate the plan quality in terms of target conformity and delivery efficiency. Methods: Five cervical carcinoma cases were planned with the Corvus, Monaco, Pinnacle and Xio TPSs by experienced planners using appropriate optimization parameters and dose constraints to meet the clinical acceptance criteria. Plans were normalized for at least 95% of PTV to receive the prescription dose (Dp). Dose-volume histograms and isodose distributions were compared. Other quantities such as Dmin(the minimum dose receivedmore » by 99% of GTV/PTV), Dmax(the maximum dose received by 1% of GTV/PTV), D100, D95, D90, V110%, V105%, V100% (the volume of GTV/PTV receiving 110%, 105%, 100% of Dp), conformity index(CI), homogeneity index (HI), the volume of receiving 40Gy and 50 Gy to rectum (V40,V50) ; the volume of receiving 30Gy and 50 Gy to bladder (V30,V50) were evaluated. Total segments and MUs were also compared. Results: While all plans meet target dose specifications and normal tissue constraints, the maximum GTVCI of Pinnacle plans was up to 0.74 and the minimum of Corvus plans was only 0.21, these four TPSs PTVCI had significant difference. The GTVHI and PTVHI of Pinnacle plans are all very low and show a very good dose distribution. Corvus plans received the higer dose of normal tissue. The Monaco plans require significantly less segments and MUs to deliver than the other plans. Conclusion: To deliver on a Varian linear-accelerator, the Pinnacle plans show a very good dose distribution. Corvus plans received the higer dose of normal tissue. The Monaco plans have faster beam delivery.« less

  16. SU-E-T-571: Prostate IMRT QA: Prediction of the Range of Rectal NTCP Using a 2D Field Approach Based on Variations of the Rectal Wall Motion and Thickness.

    PubMed

    Grigorov, G; Chow, J; Foster, K

    2012-06-01

    The aims of this study is to (1) introduce a 2D field of possible rectal normal tissue complication probability (NTCP) in prostate intensity modulated radiotherapy (IMRT) plan, so that based on a given prescribed dose the rectal NTCP is merely a function of the rectal wall thickness and rectal motion; and (2) separate the 2D field of rectal NTCP into area of low risk and area of high risk for rectal toxicity < Grade II, based on the threshold rectal NTCP. The 2D field of NTCP model was developed using ten randomly selected prostate IMRT plans. The clinical rectal geometry was initially represented by the cylindrical contour in the treatment planning system. Different combinations of rectal motions, rectal wall thicknesses, planning target volume margins and prescribed doses were used to determine the NTCP in prostate IMRT plans. It was found that the functions bordering the 2D field for the given AP, LR and SI direction can be described as exponential, quadratic and linear equations, respectively. A ratio of the area of 2D field containing data of the low risk NTCP to the entire area of the field was introduced and calculated. Although our method is based on the Kutcher's dose response model and published tissue parameters, other mathematical models can be used in our approach. The 2D field of rectal NTCP is useful to estimate the rectal NTCP range in the prostate pre-treatment and treatment QA. Our method can determine the patient's threshold immobilization for a given rectal wall thickness so that prescribed dose can be delivered to the prostate to avoid rectal complication. Our method is also applicable to multi-phase prostate IMRT, and can be adapted to any treatment planning systems. © 2012 American Association of Physicists in Medicine.

  17. Robust optimization methods for cardiac sparing in tangential breast IMRT

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Mahmoudzadeh, Houra, E-mail: houra@mie.utoronto.ca; Lee, Jenny; Chan, Timothy C. Y.

    Purpose: In left-sided tangential breast intensity modulated radiation therapy (IMRT), the heart may enter the radiation field and receive excessive radiation while the patient is breathing. The patient’s breathing pattern is often irregular and unpredictable. We verify the clinical applicability of a heart-sparing robust optimization approach for breast IMRT. We compare robust optimized plans with clinical plans at free-breathing and clinical plans at deep inspiration breath-hold (DIBH) using active breathing control (ABC). Methods: Eight patients were included in the study with each patient simulated using 4D-CT. The 4D-CT image acquisition generated ten breathing phase datasets. An average scan was constructedmore » using all the phase datasets. Two of the eight patients were also imaged at breath-hold using ABC. The 4D-CT datasets were used to calculate the accumulated dose for robust optimized and clinical plans based on deformable registration. We generated a set of simulated breathing probability mass functions, which represent the fraction of time patients spend in different breathing phases. The robust optimization method was applied to each patient using a set of dose-influence matrices extracted from the 4D-CT data and a model of the breathing motion uncertainty. The goal of the optimization models was to minimize the dose to the heart while ensuring dose constraints on the target were achieved under breathing motion uncertainty. Results: Robust optimized plans were improved or equivalent to the clinical plans in terms of heart sparing for all patients studied. The robust method reduced the accumulated heart dose (D10cc) by up to 801 cGy compared to the clinical method while also improving the coverage of the accumulated whole breast target volume. On average, the robust method reduced the heart dose (D10cc) by 364 cGy and improved the optBreast dose (D99%) by 477 cGy. In addition, the robust method had smaller deviations from the planned dose to the

  18. Dosimetric accuracy of Kodak EDR2 film for IMRT verifications.

    PubMed

    Childress, Nathan L; Salehpour, Mohammad; Dong, Lei; Bloch, Charles; White, R Allen; Rosen, Isaac I

    2005-02-01

    Patient-specific intensity-modulated radiotherapy (IMRT) verifications require an accurate two-dimensional dosimeter that is not labor-intensive. We assessed the precision and reproducibility of film calibrations over time, measured the elemental composition of the film, measured the intermittency effect, and measured the dosimetric accuracy and reproducibility of calibrated Kodak EDR2 film for single-beam verifications in a solid water phantom and for full-plan verifications in a Rexolite phantom. Repeated measurements of the film sensitometric curve in a single experiment yielded overall uncertainties in dose of 2.1% local and 0.8% relative to 300 cGy. 547 film calibrations over an 18-month period, exposed to a range of doses from 0 to a maximum of 240 MU or 360 MU and using 6 MV or 18 MV energies, had optical density (OD) standard deviations that were 7%-15% of their average values. This indicates that daily film calibrations are essential when EDR2 film is used to obtain absolute dose results. An elemental analysis of EDR2 film revealed that it contains 60% as much silver and 20% as much bromine as Kodak XV2 film. EDR2 film also has an unusual 1.69:1 silver:halide molar ratio, compared with the XV2 film's 1.02:1 ratio, which may affect its chemical reactions. To test EDR2's intermittency effect, the OD generated by a single 300 MU exposure was compared to the ODs generated by exposing the film 1 MU, 2 MU, and 4 MU at a time to a total of 300 MU. An ion chamber recorded the relative dose of all intermittency measurements to account for machine output variations. Using small MU bursts to expose the film resulted in delivery times of 4 to 14 minutes and lowered the film's OD by approximately 2% for both 6 and 18 MV beams. This effect may result in EDR2 film underestimating absolute doses for patient verifications that require long delivery times. After using a calibration to convert EDR2 film's OD to dose values, film measurements agreed within 2% relative

  19. SU-E-T-287: Dose Verification On the Variation of Target Volume and Organ at Risk in Preradiation Chemotherapy IMRT for Nasopharyngeal Cancer

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zhang, X; Kong, L; Wang, J

    2015-06-15

    Purpose: To quantify the target volume and organ at risk of nasopharyngeal carcinoma (NPC) patients with preradiation chemotherapy based on CT scanned during intensity-modulated radiotherapy (IMRT), and recalculate the dose distribution. Methods: Seven patients with NPC and preradiation chemotherapy, treated with IMRT (35 to 37 fractions) were reviewed. Repeat CT scanning was required to all of the patients during the radiotherapy, and the number of repeat CTs varies from 2 to 6. The plan CT and repeat CT were generated by different CT scanner. To ensure crespectively on the same IMPT plan. The real dose distribution was calculated by deformablemore » registration and weighted method in Raystation (v 4.5.1). The fraction of each dose is based on radiotherapy record. The volumetric and dose differences among these images were calculated for nascIpharyngeal tumor and retro-pharyngeal lymph nodes (GTV-NX), neck lymph nodes(GTV-ND), and parotid glands. Results: The volume variation in GTV-NX from CT1 to CT2 was 1.15±3.79%, and in GTV-LN −0.23±4.93%. The volume variation in left parotid from CT1 to CT2 was −6.79±11.91%, and in right parotid −3.92±8.80%. In patient 2, the left parotid volume were decreased remarkably, as a Result, the V30 and V40 of it were increased as well. Conclusion: The target volume of patients with NPC varied lightly during IMRT. It shows that preradiation chemotherapy can control the target volume variation and perform a good dose repeatability. Also, the decreasing volume of parotid in some patient might increase the dose of it, which might course potential complications.« less

  20. Toxicities Affecting Quality of Life After Chemo-IMRT of Oropharyngeal Cancer: Prospective Study of Patient-Reported, Observer-Rated, and Objective Outcomes

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hunter, Klaudia U.; Schipper, Matthew; Feng, Felix Y.

    2013-03-15

    Purpose: To test the hypothesis that intensity modulated radiation therapy (IMRT) aiming to spare the salivary glands and swallowing structures would reduce or eliminate the effects of xerostomia and dysphagia on quality of life (QOL). Methods and Materials: In this prospective, longitudinal study, 72 patients with stage III-IV oropharyngeal cancer were treated uniformly with definitive chemo-IMRT sparing the salivary glands and swallowing structures. Overall QOL was assessed by summary scores of the Head Neck QOL (HNQOL) and University of Washington QOL (UWQOL) questionnaires, as well as the HNQOL “Overall Bother” question. Quality of life, observer-rated toxicities (Common Toxicity Criteria Adversemore » Effects scale, version 2), and objective evaluations (videofluoroscopy assessing dysphagia and saliva flow rates assessing xerostomia) were recorded from before therapy through 2 years after therapy. Correlations between toxicities/objective evaluations and overall QOL were assessed using longitudinal repeated measures of analysis and Pearson correlations. Results: All observer-rated toxicities and QOL scores worsened 1-3 months after therapy and improved through 12 months, with minor further improvements through 24 months. At 12 months, dysphagia grades 0-1, 2, and 3, were observed in 95%, 4%, and 1% of patients, respectively. Using all posttherapy observations, observer-rated dysphagia was highly correlated with all overall QOL measures (P<.0001), whereas xerostomia and mucosal and voice toxicities were significantly correlated with some, but not all, overall QOL measures, with lower correlation coefficients than dysphagia. Late overall QOL (≥6 or ≥12 months after therapy) was primarily associated with observer-rated dysphagia, and to a lesser extent with xerostomia. Videofluoroscopy scores, but not salivary flows, were significantly correlated with some of the overall QOL measures. Conclusion: After chemo-IMRT, although late dysphagia was on average

  1. Development and evaluation of an end‐to‐end test for head and neck IMRT with a novel multiple‐dosimetric modality phantom

    PubMed Central

    Zakjevskii, Viatcheslav V.; Knill, Cory S.; Rakowski, Joseph. T.

    2016-01-01

    A comprehensive end‐to‐end test for head and neck IMRT treatments was developed using a custom phantom designed to utilize multiple dosimetry devices. Initial end‐to‐end test and custom H&N phantom were designed to yield maximum information in anatomical regions significant to H&N plans with respect to: (i) geometric accuracy, (ii) dosimetric accuracy, and (iii) treatment reproducibility. The phantom was designed in collaboration with Integrated Medical Technologies. The phantom was imaged on a CT simulator and the CT was reconstructed with 1 mm slice thickness and imported into Varian's Eclipse treatment planning system. OARs and the PTV were contoured with the aid of Smart Segmentation. A clinical template was used to create an eight‐field IMRT plan and dose was calculated with heterogeneity correction on. Plans were delivered with a TrueBeam equipped with a high definition MLC. Preliminary end‐to‐end results were measured using film, ion chambers, and optically stimulated luminescent dosimeters (OSLDs). Ion chamber dose measurements were compared to the treatment planning system. Films were analyzed with FilmQA Pro using composite gamma index. OSLDs were read with a MicroStar reader using a custom calibration curve. Final phantom design incorporated two axial and one coronal film planes with 18 OSLD locations adjacent to those planes as well as four locations for IMRT ionization chambers below inferior film plane. The end‐to‐end test was consistently reproducible, resulting in average gamma pass rate greater than 99% using 3%/3 mm analysis criteria, and average OSLD and ion chamber measurements within 1% of planned dose. After initial calibration of OSLD and film systems, the end‐to‐end test provides next‐day results, allowing for integration in routine clinical QA. Preliminary trials have demonstrated that our end‐to‐end is a reproducible QA tool that enables the ongoing evaluation of dosimetric and geometric accuracy of clinical

  2. Use of implanted gold fiducial markers with MV-CBCT image-guided IMRT for pancreatic tumours.

    PubMed

    Packard, Matthew; Gayou, Olivier; Gurram, Krishna; Weiss, Brandon; Thakkar, Shyam; Kirichenko, Alexander

    2015-08-01

    Visualisation of soft tissues such as pancreatic tumours by mega-voltage cone beam CT (MV-CBCT) is frequently difficult and daily localisation is often based on more easily seen adjacent bony anatomy. Fiducial markers implanted into pancreatic tumours serve as surrogates for tumour position and may more accurately represent absolute tumour position. Differences in daily shifts based on alignment to implanted fiducial markers vs. alignment to adjacent bony anatomy were compared. Gold fiducial markers were placed into the pancreatic tumour under endoscopic ultrasound (EUS) guidance in 12 patients. Patients subsequently received image-guided intensity-modulated radiation therapy (IG-IMRT). MV-CBCT was performed prior to each fraction and isocentre shifts were performed based on alignment to the fiducial markers. We retrospectively reviewed archived MV-CBCT datasets and calculated shift differences in the left-right (LR), superior-inferior (SI) and anterior-posterior (AP) axes relative to shifts based on alignment to adjacent bony anatomy. Two hundred forty-three fractions were analysed. The mean absolute difference in isocentre shifts between the fiducial markers and those aligned to bony anatomy was 3.4 mm (range 0-13 mm), 6.3 mm (range 0-21 mm) and 2.6 mm (range 0-12 mm), in LR, SI and AP directions, respectively. The mean three-dimensional vector shift difference between markers vs. bony anatomy alignment was 8.6 mm. These data suggest that fiducial markers used in conjunction with MV-CBCT improve the accuracy of daily target delineation compared with localisation using adjacent bony anatomy and that gold fiducial markers using MV-CBCT alignment are a viable option for target localisation during IG-IMRT. © 2015 The Royal Australian and New Zealand College of Radiologists.

  3. 4D radiobiological modelling of the interplay effect in conventionally and hypofractionated lung tumour IMRT.

    PubMed

    Selvaraj, J; Uzan, J; Baker, C; Nahum, A

    2015-01-01

    To study the impact of the interplay between respiration-induced tumour motion and multileaf collimator leaf movements in intensity-modulated radiotherapy (IMRT) as a function of number of fractions, dose rate on population mean tumour control probability ([Formula: see text]) using an in-house developed dose model. Delivered dose was accumulated in a voxel-by-voxel basis inclusive of tumour motion over the course of treatment. The effect of interplay on dose and [Formula: see text] was studied for conventionally and hypofractionated treatments using digital imaging and communications in medicine data sets. Moreover, the effect of dose rate on interplay was also studied for single-fraction treatments. Simulations were repeated several times to obtain [Formula: see text] for each plan. The average variation observed in mean dose to the target volumes were -0.76% ± 0.36% for the 20-fraction treatment and -0.26% ± 0.68% and -1.05% ± 0.98% for the three- and single-fraction treatments, respectively. For the 20-fraction treatment, the drop in [Formula: see text] was -1.05% ± 0.39%, whereas for the three- and single-fraction treatments, it was -2.80% ± 1.68% and -4.00% ± 2.84%, respectively. By reducing the dose rate from 600 to 300 MU min(-1) for the single-fraction treatments, the drop in [Formula: see text] was reduced by approximately 1.5%. The effect of interplay on [Formula: see text] is negligible for conventionally fractionated treatments, whereas considerable drop in [Formula: see text] is observed for the three- and single-fraction treatments. Reduced dose rate could be used in hypofractionated treatments to reduce the interplay effect. A novel in silico dose model is presented to determine the impact of interplay effect in IMRT treatments on [Formula: see text].

  4. 4D radiobiological modelling of the interplay effect in conventionally and hypofractionated lung tumour IMRT

    PubMed Central

    Uzan, J; Baker, C; Nahum, A

    2015-01-01

    Objective: To study the impact of the interplay between respiration-induced tumour motion and multileaf collimator leaf movements in intensity-modulated radiotherapy (IMRT) as a function of number of fractions, dose rate on population mean tumour control probability () using an in-house developed dose model. Methods: Delivered dose was accumulated in a voxel-by-voxel basis inclusive of tumour motion over the course of treatment. The effect of interplay on dose and was studied for conventionally and hypofractionated treatments using digital imaging and communications in medicine data sets. Moreover, the effect of dose rate on interplay was also studied for single-fraction treatments. Simulations were repeated several times to obtain for each plan. Results: The average variation observed in mean dose to the target volumes were −0.76% ± 0.36% for the 20-fraction treatment and −0.26% ± 0.68% and −1.05% ± 0.98% for the three- and single-fraction treatments, respectively. For the 20-fraction treatment, the drop in was −1.05% ± 0.39%, whereas for the three- and single-fraction treatments, it was −2.80% ± 1.68% and −4.00% ± 2.84%, respectively. By reducing the dose rate from 600 to 300 MU min−1 for the single-fraction treatments, the drop in was reduced by approximately 1.5%. Conclusion: The effect of interplay on is negligible for conventionally fractionated treatments, whereas considerable drop in is observed for the three- and single-fraction treatments. Reduced dose rate could be used in hypofractionated treatments to reduce the interplay effect. Advances in knowledge: A novel in silico dose model is presented to determine the impact of interplay effect in IMRT treatments on . PMID:25251400

  5. Dosimetric evaluation of IMRT plan for homogenous and inhomogeneous medium using AAPM TG-119 protocol

    NASA Astrophysics Data System (ADS)

    Fatimah, L. A. N.; Wibowo, W. E.; Pawiro, S. A.

    2017-05-01

    The American Association of Physicists in Medicine (AAPM) TG-119 protocol has been applied for dose verification in IMRT technique. However, some criteria in the protocol need to be verified for inhomogeneous medium and small volume targets. Hence, the purpose of this study was to verify the assessment criteria of dose verification in AAPM TG-119 for inhomogeneous medium and small volume targets. The work has been conducted by dose verification for homogeneous (phantom A) and inhomogeneous phantoms (phantom B and C) on two geometrical targets: C-shape and circular targets. The targets were simulated using 7 static dMLC IMRT fields at two different depths of 5 g/cm2 and 10 g/cm2. The dose optimisation and calculation were done by using Pinnacle3 for 6 MV photons beam. The planning objectives were set according to AAPM TG-119 parameters. The plan analysis was conducted by Conformity Index and Homogeneity Index. The point dose measurements were conducted with Exradin A16, Semiflex 0.125cc, and Gafchromic EBT3. The plan results show that CI for C-shape target is in the range of 0.710-0.999 at 10 g/cm2 depth and 0.691-1.613 at 5 g/cm2. In addition, HI for C-shape and circular were in the range of 6.3%-58.7% and 5.4%-87.1% for 10 g/cm2 depth. The measurement results show that the dose measurement at inhomogeneous medium and small volume targets are much lower than the criteria in AAPM TG-119. In conclusion, the criteria in the AAPM TG-119 cannot be fully implemented for inhomogeneous medium and small volume targets.

  6. First muon acceleration using a radio-frequency accelerator

    NASA Astrophysics Data System (ADS)

    Bae, S.; Choi, H.; Choi, S.; Fukao, Y.; Futatsukawa, K.; Hasegawa, K.; Iijima, T.; Iinuma, H.; Ishida, K.; Kawamura, N.; Kim, B.; Kitamura, R.; Ko, H. S.; Kondo, Y.; Li, S.; Mibe, T.; Miyake, Y.; Morishita, T.; Nakazawa, Y.; Otani, M.; Razuvaev, G. P.; Saito, N.; Shimomura, K.; Sue, Y.; Won, E.; Yamazaki, T.

    2018-05-01

    Muons have been accelerated by using a radio-frequency accelerator for the first time. Negative muonium atoms (Mu- ), which are bound states of positive muons (μ+) and two electrons, are generated from μ+'s through the electron capture process in an aluminum degrader. The generated Mu- 's are initially electrostatically accelerated and injected into a radio-frequency quadrupole linac (RFQ). In the RFQ, the Mu- 's are accelerated to 89 keV. The accelerated Mu- 's are identified by momentum measurement and time of flight. This compact muon linac opens the door to various muon accelerator applications including particle physics measurements and the construction of a transmission muon microscope.

  7. TL and OSL dose response of LiF:Mg,Ti and Al2O3:C dosimeters using a PMMA phantom for IMRT technique quality assurance.

    PubMed

    Matsushima, Luciana C; Veneziani, Glauco R; Sakuraba, Roberto K; Cruz, José C; Campos, Letícia L

    2015-06-01

    The principle of IMRT is to treat a patient from a number of different directions (or continuous arcs) with beams of nonuniform fluences, which have been optimized to deliver a high dose to the target volume and an acceptably low dose to the surrounding normal structures (Khan, 2010). This study intends to provide information to the physicist regarding the application of different dosimeters type, phantoms and analysis technique for Intensity Modulated Radiation Therapy (IMRT) dose distributions evaluation. The measures were performed using dosimeters of LiF:Mg,Ti and Al2O3:C evaluated by techniques of thermoluminescent (TL) and Optically Stimulated Luminescence (OSL). A polymethylmethacrylate (PMMA) phantom with five cavities, two principal target volumes considered like tumours to be treated and other three cavities to measure the scattered radiation dose was developed to carried out the measures. Copyright © 2015 Elsevier Ltd. All rights reserved.

  8. Phase 2 trial of bortezomib in combination with rituximab plus hyperfractionated cyclophosphamide, vincristine, doxorubicin, and dexamethasone alternating with bortezomib, rituximab, methotrexate, and cytarabine for untreated mantle cell lymphoma.

    PubMed

    Romaguera, Jorge E; Wang, Michael; Feng, Lei; Fayad, Luis E; Hagemeister, Frederick; McLaughlin, Peter; Rodriguez, M Alma; Fanale, Michelle; Orlowski, Robert; Kwak, Larry W; Neelapu, Sattva; Oki, Yasuhiro; Pro, Barbara; Younes, Anas; Samaniego, Felipe; Fowler, Nathan; Hartig, Kimberly; Valentinetti, Marisa; Smith, Judy; Ford, Peggy; Naig, Adam; Medeiros, L Jeffrey; Kantarjian, Hagop M; Goy, Andre

    2018-05-03

    Although the outcomes of patients with mantle cell lymphoma (MCL) have improved, there is still no cure. Bortezomib has a 33% response rate in relapsed/refractory MCL and has shown additive and/or synergistic effects in preclinical trials with known effective agents. This is a report of a prospective phase 2 trial of bortezomib added to rituximab plus hyperfractionated cyclophosphamide, vincristine, doxorubicin, and dexamethasone (BzR-hyperCVAD)/rituximab, high-dose methotrexate, and high-dose cytarabine (BzR-MA) for 95 patients with newly diagnosed MCL. The overall and complete response rates were 100% and 82%, respectively. Hematologic toxicity was high but expected and did not lead to an increased incidence of neutropenic fever or dose reductions in comparison with a similar reported regimen without bortezomib. After a median follow-up of 44 months, the median overall survival had not been reached, and the time to treatment failure (TTF) was 55 months, which is not different from that of historical controls. BzR-hyperCVAD/BzR-MA at the dose and schedule studied produced high rates of response and a TTF similar to that of historical reports without bortezomib. Cancer 2018. © 2018 American Cancer Society. © 2018 American Cancer Society.

  9. Dosimetric comparison of IMRT rectal and anal canal plans generated using an anterior dose avoidance structure

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Leicher, Brian, E-mail: bleicher@wpahs.org; Day, Ellen; Colonias, Athanasios

    2014-10-01

    To describe a dosimetric method using an anterior dose avoidance structure (ADAS) during the treatment planning process for intensity-modulated radiation therapy (IMRT) for patients with anal canal and rectal carcinomas. A total of 20 patients were planned on the Elekta/CMS XiO treatment planning system, version 4.5.1 (Maryland Heights MO) with a superposition algorithm. For each patient, 2 plans were created: one employing an ADAS (ADAS plan) and the other replanned without an ADAS (non-ADAS plan). The ADAS was defined to occupy the volume between the inguinal nodes and primary target providing a single organ at risk that is completely outsidemore » of the target volume. Each plan used the same beam parameters and was analyzed by comparing target coverage, overall plan dose conformity using a conformity number (CN) equation, bowel dose-volume histograms, and the number of segments, daily treatment duration, and global maximum dose. The ADAS and non-ADAS plans were equivalent in target coverage, mean global maximum dose, and sparing of small bowel in low-dose regions (5, 10, 15, and 20 Gy). The mean difference between the CN value for the non-ADAS plans and ADAS plans was 0.04 ± 0.03 (p < 0.001). The mean difference in the number of segments was 15.7 ± 12.7 (p < 0.001) in favor of ADAS plans. The ADAS plan delivery time was shorter by 2.0 ± 1.5 minutes (p < 0.001) than the non-ADAS one. The ADAS has proven to be a powerful tool when planning rectal and anal canal IMRT cases with critical structures partially contained inside the target volume.« less

  10. PARTICLE ACCELERATOR

    DOEpatents

    Teng, L.C.

    1960-01-19

    ABS>A combination of two accelerators, a cyclotron and a ring-shaped accelerator which has a portion disposed tangentially to the cyclotron, is described. Means are provided to transfer particles from the cyclotron to the ring accelerator including a magnetic deflector within the cyclotron, a magnetic shield between the ring accelerator and the cyclotron, and a magnetic inflector within the ring accelerator.

  11. Dosimetric impact in the dose-volume histograms of rectal and vesical wall contouring in prostate cancer IMRT treatments.

    PubMed

    Gómez, Laura; Andrés, Carlos; Ruiz, Antonio

    2017-01-01

    The main purpose of this study was to evaluate the differences in dose-volume histograms of IMRT treatments for prostate cancer based on the delineation of the main organs at risk (rectum and bladder) as solid organs or by contouring their wall. Rectum and bladder have typically been delineated as solid organs, including the waste material, which, in practice, can lead to an erroneous assessment of the risk of adverse effects. A retrospective study was made on 25 patients treated with IMRT radiotherapy for prostate adenocarcinoma. 76.32 Gy in 36 fractions was prescribed to the prostate and seminal vesicles. In addition to the delineation of the rectum and bladder as solid organs (including their content), the rectal and bladder wall were also delineated and the resulting dose-volume histograms were analyzed for the two groups of structures. Data analysis shows statistically significant differences in the main parameters used to assess the risk of toxicity of a prostate radiotherapy treatment. Higher doses were received on the rectal and bladder walls compared to doses received on the corresponding solid organs. The observed differences in terms of received doses to the rectum and bladder based on the method of contouring could gain greater importance in inverse planning treatments, where the treatment planning system optimizes the dose in these volumes. So, one should take into account the method of delineating of these structures to make a clinical decision regarding dose limitation and risk assessment of chronic toxicity.

  12. Acceleration Modes and Transitions in Pulsed Plasma Accelerators

    NASA Technical Reports Server (NTRS)

    Polzin, Kurt A.; Greve, Christine M.

    2018-01-01

    Pulsed plasma accelerators typically operate by storing energy in a capacitor bank and then discharging this energy through a gas, ionizing and accelerating it through the Lorentz body force. Two plasma accelerator types employing this general scheme have typically been studied: the gas-fed pulsed plasma thruster and the quasi-steady magnetoplasmadynamic (MPD) accelerator. The gas-fed pulsed plasma accelerator is generally represented as a completely transient device discharging in approximately 1-10 microseconds. When the capacitor bank is discharged through the gas, a current sheet forms at the breech of the thruster and propagates forward under a j (current density) by B (magnetic field) body force, entraining propellant it encounters. This process is sometimes referred to as detonation-mode acceleration because the current sheet representation approximates that of a strong shock propagating through the gas. Acceleration of the initial current sheet ceases when either the current sheet reaches the end of the device and is ejected or when the current in the circuit reverses, striking a new current sheet at the breech and depriving the initial sheet of additional acceleration. In the quasi-steady MPD accelerator, the pulse is lengthened to approximately 1 millisecond or longer and maintained at an approximately constant level during discharge. The time over which the transient phenomena experienced during startup typically occur is short relative to the overall discharge time, which is now long enough for the plasma to assume a relatively steady-state configuration. The ionized gas flows through a stationary current channel in a manner that is sometimes referred to as the deflagration-mode of operation. The plasma experiences electromagnetic acceleration as it flows through the current channel towards the exit of the device. A device that had a short pulse length but appeared to operate in a plasma acceleration regime different from the gas-fed pulsed plasma

  13. Is it sufficient to repeat LINEAR accelerator stereotactic radiosurgery in choroidal melanoma?

    PubMed

    Furdova, A; Horkovicova, K; Justusova, P; Sramka, M

    One day session LINAC based stereotactic radiosurgery (SRS) at LINAC accelerator is a method of "conservative" attitude to treat the intraocular malignant uveal melanoma. We used model Clinac 600 C/D Varian (system Aria, planning system Corvus version 6.2 verification IMRT OmniPro) with 6 MeV X by rigid immobilization of the eye to the Leibinger frame. The stereotactic treatment planning after fusion of CT and MRI was optimized according to the critical structures (lens, optic nerve, also lens and optic nerve at the contralateral side, chiasm). The first plan was compared and the best plan was applied for therapy at C LINAC accelerator. The planned therapeutic dose was 35.0 Gy by 99 % of DVH (dose volume histogram). In our clinical study in the group of 125 patients with posterior uveal melanoma treated with SRS, in 2 patients (1.6 %) was repeated SRS indicated. Patient age of the whole group ranged from 25 to 81 years with a median of 54 TD was 35.0 Gy. In 2 patients after 5 year interval after stereotactic radiosurgery for uveal melanoma stage T1, the tumor volume increased to 50 % of the primary tumor volume and repeated SRS was necessary. To find out the changes in melanoma characteristics after SRS in long term interval after irradiation is necessary to follow up the patient by an ophthalmologist regularly. One step LINAC based stereotactic radiosurgery with a single dose 35.0 Gy is one of treatment options to treat T1 to T3 stage posterior uveal melanoma and to preserve the eye globe. In some cases it is possible to repeat the SRS after more than 5 year interval (Fig. 8, Ref. 23).

  14. Four-dimensional dose distributions of step-and-shoot IMRT delivered with real-time tumor tracking for patients with irregular breathing: Constant dose rate vs dose rate regulation

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Yang Xiaocheng; Han-Oh, Sarah; Gui Minzhi

    2012-09-15

    Purpose: Dose-rate-regulated tracking (DRRT) is a tumor tracking strategy that programs the MLC to track the tumor under regular breathing and adapts to breathing irregularities during delivery using dose rate regulation. Constant-dose-rate tracking (CDRT) is a strategy that dynamically repositions the beam to account for intrafractional 3D target motion according to real-time information of target location obtained from an independent position monitoring system. The purpose of this study is to illustrate the differences in the effectiveness and delivery accuracy between these two tracking methods in the presence of breathing irregularities. Methods: Step-and-shoot IMRT plans optimized at a reference phase weremore » extended to remaining phases to generate 10-phased 4D-IMRT plans using segment aperture morphing (SAM) algorithm, where both tumor displacement and deformation were considered. A SAM-based 4D plan has been demonstrated to provide better plan quality than plans not considering target deformation. However, delivering such a plan requires preprogramming of the MLC aperture sequence. Deliveries of the 4D plans using DRRT and CDRT tracking approaches were simulated assuming the breathing period is either shorter or longer than the planning day, for 4 IMRT cases: two lung and two pancreatic cases with maximum GTV centroid motion greater than 1 cm were selected. In DRRT, dose rate was regulated to speed up or slow down delivery as needed such that each planned segment is delivered at the planned breathing phase. In CDRT, MLC is separately controlled to follow the tumor motion, but dose rate was kept constant. In addition to breathing period change, effect of breathing amplitude variation on target and critical tissue dose distribution is also evaluated. Results: Delivery of preprogrammed 4D plans by the CDRT method resulted in an average of 5% increase in target dose and noticeable increase in organs at risk (OAR) dose when patient breathing is either 10

  15. SU-F-E-06: Dosimetric Characterization of Small Photons Beams of a Novel Linear Accelerator

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Almonte, A; Polanco, G; Sanchez, E

    2016-06-15

    Purpose: The aim of the present contribution was to measure the main dosimetric quantities of small fields produced by UNIQUE and evaluate its matching with the corresponding dosimetric data of one 21EX conventional linear accelerator (Varian) in operation at the same center. The second step was to evaluate comparative performance of the EDGE diode detector and the PinPoint micro-ionization chamber for dosimetry of small fields. Methods: UNIQUE is configured with MLC (120 leaves with 0.5 cm leaf width) and a single low photon energy of 6 MV. Beam data were measured with scanning EDGE diode detector (volume of 0.019 mm{supmore » 3}), a PinPoint micro-ionization chamber (PTW) and for larger fields (≥ 4×4cm{sup 2}) a PTW Semi flex chamber (0.125 cm{sup 3}) was used. The scanning system used was the 3D cylindrical tank manufactured by Sun Nuclear, Inc. The measurement of PDD and profiles were done at 100 cm SSD and 1.5 depth; the relative output factors were measured at 10 cm depth. Results: PDD and the profile data showed less than 1% variation between the two linear accelerators for fields size between 2×2 cm{sup 2} and 5×5cm{sup 2}. Output factor differences was less than 1% for field sizes between 3×3 cm{sup 2} and 10×10 cm{sup 2} and less of 1.5 % for fields of 1.5×1.5 cm{sup 2} and 2×2 cm{sup 2} respectively. The dmax value of the EDGE diode detector, measured from the PDD, was 8.347 mm for 0.5×0,5cm{sup 2} for UNIQUE. The performance of EDGE diode detector was comparable for all measurements in small fields. Conclusion: UNIQUE linear accelerator show similar dosimetrics characteristics as conventional 21EX Varian linear accelerator for small, medium and large field sizes.EDGE detector show good performance by measuring dosimetrics quantities in small fields typically used in IMRT and radiosurgery treatments.« less

  16. iCycle: Integrated, multicriterial beam angle, and profile optimization for generation of coplanar and noncoplanar IMRT plans

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Breedveld, Sebastiaan; Storchi, Pascal R. M.; Voet, Peter W. J.

    2012-02-15

    Purpose: To introduce iCycle, a novel algorithm for integrated, multicriterial optimization of beam angles, and intensity modulated radiotherapy (IMRT) profiles. Methods: A multicriterial plan optimization with iCycle is based on a prescription called wish-list, containing hard constraints and objectives with ascribed priorities. Priorities are ordinal parameters used for relative importance ranking of the objectives. The higher an objective priority is, the higher the probability that the corresponding objective will be met. Beam directions are selected from an input set of candidate directions. Input sets can be restricted, e.g., to allow only generation of coplanar plans, or to avoid collisions betweenmore » patient/couch and the gantry in a noncoplanar setup. Obtaining clinically feasible calculation times was an important design criterium for development of iCycle. This could be realized by sequentially adding beams to the treatment plan in an iterative procedure. Each iteration loop starts with selection of the optimal direction to be added. Then, a Pareto-optimal IMRT plan is generated for the (fixed) beam setup that includes all so far selected directions, using a previously published algorithm for multicriterial optimization of fluence profiles for a fixed beam arrangement Breedveld et al.[Phys. Med. Biol. 54, 7199-7209 (2009)]. To select the next direction, each not yet selected candidate direction is temporarily added to the plan and an optimization problem, derived from the Lagrangian obtained from the just performed optimization for establishing the Pareto-optimal plan, is solved. For each patient, a single one-beam, two-beam, three-beam, etc. Pareto-optimal plan is generated until addition of beams does no longer result in significant plan quality improvement. Plan generation with iCycle is fully automated. Results: Performance and characteristics of iCycle are demonstrated by generating plans for a maxillary sinus case, a cervical cancer patient

  17. Benchmarking of a treatment planning system for spot scanning proton therapy: Comparison and analysis of robustness to setup errors of photon IMRT and proton SFUD treatment plans of base of skull meningioma

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Harding, R., E-mail: ruth.harding2@wales.nhs.uk; Trnková, P.; Lomax, A. J.

    Purpose: Base of skull meningioma can be treated with both intensity modulated radiation therapy (IMRT) and spot scanned proton therapy (PT). One of the main benefits of PT is better sparing of organs at risk, but due to the physical and dosimetric characteristics of protons, spot scanned PT can be more sensitive to the uncertainties encountered in the treatment process compared with photon treatment. Therefore, robustness analysis should be part of a comprehensive comparison between these two treatment methods in order to quantify and understand the sensitivity of the treatment techniques to uncertainties. The aim of this work was tomore » benchmark a spot scanning treatment planning system for planning of base of skull meningioma and to compare the created plans and analyze their robustness to setup errors against the IMRT technique. Methods: Plans were produced for three base of skull meningioma cases: IMRT planned with a commercial TPS [Monaco (Elekta AB, Sweden)]; single field uniform dose (SFUD) spot scanning PT produced with an in-house TPS (PSI-plan); and SFUD spot scanning PT plan created with a commercial TPS [XiO (Elekta AB, Sweden)]. A tool for evaluating robustness to random setup errors was created and, for each plan, both a dosimetric evaluation and a robustness analysis to setup errors were performed. Results: It was possible to create clinically acceptable treatment plans for spot scanning proton therapy of meningioma with a commercially available TPS. However, since each treatment planning system uses different methods, this comparison showed different dosimetric results as well as different sensitivities to setup uncertainties. The results confirmed the necessity of an analysis tool for assessing plan robustness to provide a fair comparison of photon and proton plans. Conclusions: Robustness analysis is a critical part of plan evaluation when comparing IMRT plans with spot scanned proton therapy plans.« less

  18. SU-F-BRE-13: Replacing Pre-Treatment Phantom QA with 3D In-Vivo Portal Dosimetry for IMRT Breast Cancer

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Stroom, J; Vieira, S; Greco, C

    Purpose: Pre-treatment QA of individual treatment plans requires costly linac time and physics effort. Starting with IMRT breast treatments, we aim to replace pre-treatment QA with in-vivo portal dosimetry. Methods: Our IMRT breast cancer plans are routinely measured using the ArcCheck device (SunNuclear). 2D-Gamma analysis is performed with 3%/3mm criteria and the percentage of points with gamma<1 (nG1) is calculated within the 50% isodose surface. Following AAPM recommendations, plans with nG1<90% are approved; others need further inspection and might be rejected. For this study, we used invivo portal dosimetry (IPD) to measure the 3D back-projected dose of the first threemore » fractions for IMRT breast plans. Patient setup was online corrected before for all measured fractions. To reduce patient related uncertainties, the three IPD results were averaged and 3D-gamma analysis was applied with abovementioned criteria . For a subset of patients, phantom portal dosimetry (PPD) was also performed on a slab phantom. Results: Forty consecutive breast patients with plans that fitted the EPID were analysed. The average difference between planned and IPD dose in the reference point was −0.7+/−1.6% (1SD). Variation in nG1 between the 3 invivo fractions was about 6% (1SD). The average nG1 for IPD was 89+/−6%, worse than ArcCheck (95+/−3%). This can be explained by patient related factors such as changes in anatomy and/or model deficiencies due to e.g. inhomogeneities. For the 20 cases with PPD, mean nG1 was equal to ArcCheck values, which indicates that the two systems are equally accurate. These data therefore suggest that proper criteria for 3D invivo verification of breast treatments should be nG1>80% instead of nG1>90%, which, for our breast cases, would result in 5% (2/40) further inspections. Conclusion: First-fraction in-vivo portal dosimetry using new gamma-evaluation criteria will replace phantom measurements in our institution, saving resources and

  19. SU-E-T-20: A Correlation Study of 2D and 3D Gamma Passing Rates for Prostate IMRT Plans

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zhang, D; Sun Yat-sen University Cancer Center, Guangzhou, Guangdong; Wang, B

    2015-06-15

    Purpose: To investigate the correlation between the two-dimensional gamma passing rate (2D %GP) and three-dimensional gamma passing rate (3D %GP) in prostate IMRT quality assurance. Methods: Eleven prostate IMRT plans were randomly selected from the clinical database and were used to obtain dose distributions in the phantom and patient. Three types of delivery errors (MLC bank sag errors, central MLC errors and monitor unit errors) were intentionally introduced to modify the clinical plans through an in-house Matlab program. This resulted in 187 modified plans. The 2D %GP and 3D %GP were analyzed using different dose-difference and distance-toagreement (1%-1mm, 2%-2mm andmore » 3%-3mm) and 20% dose threshold. The 2D %GP and 3D %GP were then compared not only for the whole region, but also for the PTVs and critical structures using the statistical Pearson’s correlation coefficient (γ). Results: For different delivery errors, the average comparison of 2D %GP and 3D %GP showed different conclusions. The statistical correlation coefficients between 2D %GP and 3D %GP for the whole dose distribution showed that except for 3%/3mm criterion, 2D %GP and 3D %GP of 1%/1mm criterion and 2%/2mm criterion had strong correlations (Pearson’s γ value >0.8). Compared with the whole region, the correlations of 2D %GP and 3D %GP for PTV were better (the γ value for 1%/1mm, 2%/2mm and 3%/3mm criterion was 0.959, 0.931 and 0.855, respectively). However for the rectum, there was no correlation between 2D %GP and 3D %GP. Conclusion: For prostate IMRT, the correlation between 2D %GP and 3D %GP for the PTV is better than that for normal structures. The lower dose-difference and DTA criterion shows less difference between 2D %GP and 3D %GP. Other factors such as the dosimeter characteristics and TPS algorithm bias may also influence the correlation between 2D %GP and 3D %GP.« less

  20. A critical evaluation of the PTW 2D‐ARRAY seven29 and OCTAVIUS II phantom for IMRT and VMAT verification

    PubMed Central

    Adams, Elizabeth J.; Jordan, Thomas J.; Clark, Catharine H.; Nisbet, Andrew

    2013-01-01

    Quality assurance (QA) for intensity‐ and volumetric‐modulated radiotherapy (IMRT and VMAT) has evolved substantially. In recent years, various commercial 2D and 3D ionization chamber or diode detector arrays have become available, allowing for absolute verification with near real time results, allowing for streamlined QA. However, detector arrays are limited by their resolution, giving rise to concerns about their sensitivity to errors. Understanding the limitations of these devices is therefore critical. In this study, the sensitivity and resolution of the PTW 2D‐ARRAY seven29 and OCTAVIUS II phantom combination was comprehensively characterized for use in dynamic sliding window IMRT and RapidArc verification. Measurement comparisons were made between single acquisition and a multiple merged acquisition techniques to improve the effective resolution of the 2D‐ARRAY, as well as comparisons against GAFCHROMIC EBT2 film and electronic portal imaging dosimetry (EPID). The sensitivity and resolution of the 2D‐ARRAY was tested using two gantry angle 0° modulated test fields. Deliberate multileaf collimator (MLC) errors of 1, 2, and 5 mm and collimator rotation errors were inserted into IMRT and RapidArc plans for pelvis and head & neck sites, to test sensitivity to errors. The radiobiological impact of these errors was assessed to determine the gamma index passing criteria to be used with the 2D‐ARRAY to detect clinically relevant errors. For gamma index distributions, it was found that the 2D‐ARRAY in single acquisition mode was comparable to multiple acquisition modes, as well as film and EPID. It was found that the commonly used gamma index criteria of 3% dose difference or 3 mm distance to agreement may potentially mask clinically relevant errors. Gamma index criteria of 3%/2 mm with a passing threshold of 98%, or 2%/2 mm with a passing threshold of 95%, were found to be more sensitive. We suggest that the gamma index passing thresholds may be used

  1. Clinical Study on Lobaplatin Combined with 5-Fu and Concurrent Radiotherapy in Treating Patients with Inoperable Esophageal Cancer.

    PubMed

    Jia, Xiao-Jing; Huang, Jing-Zi

    2015-01-01

    To investigate short- and long-term treatment effects and side reactions of lobaplatin plus 5-Fu combined and concurrent radiotherapy in treating patients with inoperable middle-advanced stage esophageal cancer. Sixty patients with middle-advanced stage esophageal squamous cell cancer were retrospectively analyzed. All patients were administered lobaplatin (50 mg intravenously) for 2 h on day 1, and 5-Fu (500 mg/m2) injected intravenously from day 1 to 5 for 1 cycle, in an interval of 21 days for totally 4 cycles. At the same time, late-course accelerated hyperfractionated three-dimensional conformal radiotherapy was performed. Patients were firstly treated with conventional fractionated irradiation (1.8 Gy/d, 5 times/week, a total of 23 treatments, and DT41.4 Gy), and then treated with accelerated hyperfractionated irradiation (1.5 Gy, 2 times/d, a total of 27 Gy in 9 days, an entire course of 6-7 weeks, and DT 68.4 Gy). All patients completed treatment, including 10 complete response (CR), 41 partial response (PR), 7 stable disease (SD), and 2 progressive disease (PD). The total effective rate was 85.0% (51/60). Thirty-nine patients had an increased KPS score. One-, 2-, and 3-year survival rates were 85.3%, 57.5%, and 41.7%, respectively. The median survival time was 27 months. The adverse reactions included myelosuppression, which was mainly degreeI and II. The occurrence rate of radiation esophagitis was 17.5%. No significant hepatic or renal toxicity was observed. Lobaplatin plus 5-Fu combined with concurrent radiotherapy is safe and effective in treating patients with middle-advanced stage esophageal cancer. However, this result warrants further evaluation by randomized clinical studies.

  2. Covariant Uniform Acceleration

    NASA Astrophysics Data System (ADS)

    Friedman, Yaakov; Scarr, Tzvi

    2013-04-01

    We derive a 4D covariant Relativistic Dynamics Equation. This equation canonically extends the 3D relativistic dynamics equation , where F is the 3D force and p = m0γv is the 3D relativistic momentum. The standard 4D equation is only partially covariant. To achieve full Lorentz covariance, we replace the four-force F by a rank 2 antisymmetric tensor acting on the four-velocity. By taking this tensor to be constant, we obtain a covariant definition of uniformly accelerated motion. This solves a problem of Einstein and Planck. We compute explicit solutions for uniformly accelerated motion. The solutions are divided into four Lorentz-invariant types: null, linear, rotational, and general. For null acceleration, the worldline is cubic in the time. Linear acceleration covariantly extends 1D hyperbolic motion, while rotational acceleration covariantly extends pure rotational motion. We use Generalized Fermi-Walker transport to construct a uniformly accelerated family of inertial frames which are instantaneously comoving to a uniformly accelerated observer. We explain the connection between our approach and that of Mashhoon. We show that our solutions of uniformly accelerated motion have constant acceleration in the comoving frame. Assuming the Weak Hypothesis of Locality, we obtain local spacetime transformations from a uniformly accelerated frame K' to an inertial frame K. The spacetime transformations between two uniformly accelerated frames with the same acceleration are Lorentz. We compute the metric at an arbitrary point of a uniformly accelerated frame. We obtain velocity and acceleration transformations from a uniformly accelerated system K' to an inertial frame K. We introduce the 4D velocity, an adaptation of Horwitz and Piron s notion of "off-shell." We derive the general formula for the time dilation between accelerated clocks. We obtain a formula for the angular velocity of a uniformly accelerated object. Every rest point of K' is uniformly accelerated, and

  3. Analyzing radial acceleration with a smartphone acceleration sensor

    NASA Astrophysics Data System (ADS)

    Vogt, Patrik; Kuhn, Jochen

    2013-03-01

    This paper continues the sequence of experiments using the acceleration sensor of smartphones (for description of the function and the use of the acceleration sensor, see Ref. 1) within this column, in this case for analyzing the radial acceleration.

  4. Assessment of radiation-induced second cancer risks in proton therapy and IMRT for organs inside the primary radiation field

    NASA Astrophysics Data System (ADS)

    Paganetti, Harald; Athar, Basit S.; Moteabbed, Maryam; Adams, Judith A.; Schneider, Uwe; Yock, Torunn I.

    2012-10-01

    There is clinical evidence that second malignancies in radiation therapy occur mainly within the beam path, i.e. in the medium or high-dose region. The purpose of this study was to assess the risk for developing a radiation-induced tumor within the treated volume and to compare this risk for proton therapy and intensity-modulated photon therapy (IMRT). Instead of using data for specific patients we have created a representative scenario. Fully contoured age- and gender-specific whole body phantoms (4 year and 14 year old) were uploaded into a treatment planning system and tumor volumes were contoured based on patients treated for optic glioma and vertebral body Ewing's sarcoma. Treatment plans for IMRT and proton therapy treatments were generated. Lifetime attributable risks (LARs) for developing a second malignancy were calculated using a risk model considering cell kill, mutation, repopulation, as well as inhomogeneous organ doses. For standard fractionation schemes, the LAR for developing a second malignancy from radiation therapy alone was found to be up to 2.7% for a 4 year old optic glioma patient treated with IMRT considering a soft-tissue carcinoma risk model only. Sarcoma risks were found to be below 1% in all cases. For a 14 year old, risks were found to be about a factor of 2 lower. For Ewing's sarcoma cases the risks based on a sarcoma model were typically higher than the carcinoma risks, i.e. LAR up to 1.3% for soft-tissue sarcoma. In all cases, the risk from proton therapy turned out to be lower by at least a factor of 2 and up to a factor of 10. This is mainly due to lower total energy deposited in the patient when using proton beams. However, the comparison of a three-field and four-field proton plan also shows that the distribution of the dose, i.e. the particular treatment plan, plays a role. When using different fractionation schemes, the estimated risks roughly scale with the total dose difference in%. In conclusion, proton therapy can

  5. Continuous intensity map optimization (CIMO): A novel approach to leaf sequencing in step and shoot IMRT

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Cao Daliang; Earl, Matthew A.; Luan, Shuang

    2006-04-15

    A new leaf-sequencing approach has been developed that is designed to reduce the number of required beam segments for step-and-shoot intensity modulated radiation therapy (IMRT). This approach to leaf sequencing is called continuous-intensity-map-optimization (CIMO). Using a simulated annealing algorithm, CIMO seeks to minimize differences between the optimized and sequenced intensity maps. Two distinguishing features of the CIMO algorithm are (1) CIMO does not require that each optimized intensity map be clustered into discrete levels and (2) CIMO is not rule-based but rather simultaneously optimizes both the aperture shapes and weights. To test the CIMO algorithm, ten IMRT patient cases weremore » selected (four head-and-neck, two pancreas, two prostate, one brain, and one pelvis). For each case, the optimized intensity maps were extracted from the Pinnacle{sup 3} treatment planning system. The CIMO algorithm was applied, and the optimized aperture shapes and weights were loaded back into Pinnacle. A final dose calculation was performed using Pinnacle's convolution/superposition based dose calculation. On average, the CIMO algorithm provided a 54% reduction in the number of beam segments as compared with Pinnacle's leaf sequencer. The plans sequenced using the CIMO algorithm also provided improved target dose uniformity and a reduced discrepancy between the optimized and sequenced intensity maps. For ten clinical intensity maps, comparisons were performed between the CIMO algorithm and the power-of-two reduction algorithm of Xia and Verhey [Med. Phys. 25(8), 1424-1434 (1998)]. When the constraints of a Varian Millennium multileaf collimator were applied, the CIMO algorithm resulted in a 26% reduction in the number of segments. For an Elekta multileaf collimator, the CIMO algorithm resulted in a 67% reduction in the number of segments. An average leaf sequencing time of less than one minute per beam was observed.« less

  6. SU-E-T-538: Evaluation of IMRT Dose Calculation Based on Pencil-Beam and AAA Algorithms.

    PubMed

    Yuan, Y; Duan, J; Popple, R; Brezovich, I

    2012-06-01

    To evaluate the accuracy of dose calculation for intensity modulated radiation therapy (IMRT) based on Pencil Beam (PB) and Analytical Anisotropic Algorithm (AAA) computation algorithms. IMRT plans of twelve patients with different treatment sites, including head/neck, lung and pelvis, were investigated. For each patient, dose calculation with PB and AAA algorithms using dose grid sizes of 0.5 mm, 0.25 mm, and 0.125 mm, were compared with composite-beam ion chamber and film measurements in patient specific QA. Discrepancies between the calculation and the measurement were evaluated by percentage error for ion chamber dose and γ〉l failure rate in gamma analysis (3%/3mm) for film dosimetry. For 9 patients, ion chamber dose calculated with AAA-algorithms is closer to ion chamber measurement than that calculated with PB algorithm with grid size of 2.5 mm, though all calculated ion chamber doses are within 3% of the measurements. For head/neck patients and other patients with large treatment volumes, γ〉l failure rate is significantly reduced (within 5%) with AAA-based treatment planning compared to generally more than 10% with PB-based treatment planning (grid size=2.5 mm). For lung and brain cancer patients with medium and small treatment volumes, γ〉l failure rates are typically within 5% for both AAA and PB-based treatment planning (grid size=2.5 mm). For both PB and AAA-based treatment planning, improvements of dose calculation accuracy with finer dose grids were observed in film dosimetry of 11 patients and in ion chamber measurements for 3 patients. AAA-based treatment planning provides more accurate dose calculation for head/neck patients and other patients with large treatment volumes. Compared with film dosimetry, a γ〉l failure rate within 5% can be achieved for AAA-based treatment planning. © 2012 American Association of Physicists in Medicine.

  7. SU-F-BRD-10: Lung IMRT Planning Using Standardized Beam Bouquet Templates

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Yuan, L; Wu, Q J.; Yin, F

    2014-06-15

    Purpose: We investigate the feasibility of choosing from a small set of standardized templates of beam bouquets (i.e., entire beam configuration settings) for lung IMRT planning to improve planning efficiency and quality consistency, and also to facilitate automated planning. Methods: A set of beam bouquet templates is determined by learning from the beam angle settings in 60 clinical lung IMRT plans. A k-medoids cluster analysis method is used to classify the beam angle configuration into clusters. The value of the average silhouette width is used to determine the ideal number of clusters. The beam arrangements in each medoid of themore » resulting clusters are taken as the standardized beam bouquet for the cluster, with the corresponding case taken as the reference case. The resulting set of beam bouquet templates was used to re-plan 20 cases randomly selected from the database and the dosimetric quality of the plans was evaluated against the corresponding clinical plans by a paired t-test. The template for each test case was manually selected by a planner based on the match between the test and reference cases. Results: The dosimetric parameters (mean±S.D. in percentage of prescription dose) of the plans using 6 beam bouquet templates and those of the clinical plans, respectively, and the p-values (in parenthesis) are: lung Dmean: 18.8±7.0, 19.2±7.0 (0.28), esophagus Dmean: 32.0±16.3, 34.4±17.9 (0.01), heart Dmean: 19.2±16.5, 19.4±16.6 (0.74), spinal cord D2%: 47.7±18.8, 52.0±20.3 (0.01), PTV dose homogeneity (D2%-D99%): 17.1±15.4, 20.7±12.2 (0.03).The esophagus Dmean, cord D02 and PTV dose homogeneity are statistically better in the plans using the standardized templates, but the improvements (<5%) may not be clinically significant. The other dosimetric parameters are not statistically different. Conclusion: It's feasible to use a small number of standardized beam bouquet templates (e.g. 6) to generate plans with quality comparable to that of

  8. Community Petascale Project for Accelerator Science and Simulation: Advancing Computational Science for Future Accelerators and Accelerator Technologies

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Spentzouris, P.; /Fermilab; Cary, J.

    The design and performance optimization of particle accelerators are essential for the success of the DOE scientific program in the next decade. Particle accelerators are very complex systems whose accurate description involves a large number of degrees of freedom and requires the inclusion of many physics processes. Building on the success of the SciDAC-1 Accelerator Science and Technology project, the SciDAC-2 Community Petascale Project for Accelerator Science and Simulation (ComPASS) is developing a comprehensive set of interoperable components for beam dynamics, electromagnetics, electron cooling, and laser/plasma acceleration modelling. ComPASS is providing accelerator scientists the tools required to enable the necessarymore » accelerator simulation paradigm shift from high-fidelity single physics process modeling (covered under SciDAC1) to high-fidelity multiphysics modeling. Our computational frameworks have been used to model the behavior of a large number of accelerators and accelerator R&D experiments, assisting both their design and performance optimization. As parallel computational applications, the ComPASS codes have been shown to make effective use of thousands of processors. ComPASS is in the first year of executing its plan to develop the next-generation HPC accelerator modeling tools. ComPASS aims to develop an integrated simulation environment that will utilize existing and new accelerator physics modules with petascale capabilities, by employing modern computing and solver technologies. The ComPASS vision is to deliver to accelerator scientists a virtual accelerator and virtual prototyping modeling environment, with the necessary multiphysics, multiscale capabilities. The plan for this development includes delivering accelerator modeling applications appropriate for each stage of the ComPASS software evolution. Such applications are already being used to address challenging problems in accelerator design and optimization. The Com

  9. SU-F-BRB-14: Dosimetric Effects at Air- Tissue Boundary Due to Magnetic Field in MR-Guided IMRT/VMAT Delivery for Head and Neck Cancer

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Prior, P; Chen, X; Schultz, C

    Purpose: The advent of the MR-Linac enables real-time and high soft tissue contrast image guidance in radiation therapy (RT) delivery. Potential hot-spots at air-tissue interfaces, such as the sphenoid sinus, in RT for head and neck cancer (HNC), could potentially occur due to the electron return effect (ERE). In this study, we investigate the dosimetric effects of ERE on the dose distribution at air-tissues interfaces in HNC IMRT treatment planning. Methods: IMRT plans were generated based on planning CT’s acquired for HNC cases (nasopharynx, base of skull and paranasal sinus) using a research planning system (Monaco, v5.09.06, Elekta) employing Montemore » Carlo dose calculations with or without the presence of a transverse magnetic field (TMF). The dose in the air cavity was calculated in a 1 & 2 mm thick tissue layer, while the dose to the skin was calculated in a 1, 3 and 5 mm thick tissue layer. The maximum dose received in 1 cc volume, D1cc, were collected at different TMF strengths. Plan qualities generated with or without TMF or with increasing TMF were compared in terms of commonly-used dose-volume parameters (DVPs). Results: Variations in DVPs between plans with and without a TMF present were found to be within 5% of the planning CT. The presence of a TMF results in <5% changes in sinus air tissue interface. The largest skin dose differences with and without TMF were found within 1 mm of the skin surface Conclusion: The presence of a TMF results in practically insignificant changes in HNC IMRT plan quality, except for skin dose. Planning optimization with skin DV constraints could reduce the skin doses. This research was partially supported by Elekta Inc. (Crowley, U.K.)« less

  10. SU-C-17A-07: The Development of An MR Accelerator-Enabled Planning-To-Delivery Technique for Stereotactic Palliative Radiotherapy Treatment of Spinal Metastases

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hoogcarspel, S J; Kontaxis, C; Velden, J M van der

    2014-06-01

    Purpose: To develop an MR accelerator-enabled online planning-todelivery technique for stereotactic palliative radiotherapy treatment of spinal metastases. The technical challenges include; automated stereotactic treatment planning, online MR-based dose calculation and MR guidance during treatment. Methods: Using the CT data of 20 patients previously treated at our institution, a class solution for automated treatment planning for spinal bone metastases was created. For accurate dose simulation right before treatment, we fused geometrically correct online MR data with pretreatment CT data of the target volume (TV). For target tracking during treatment, a dynamic T2-weighted TSE MR sequence was developed. An in house developedmore » GPU based IMRT optimization and dose calculation algorithm was used for fast treatment planning and simulation. An automatically generated treatment plan developed with this treatment planning system was irradiated on a clinical 6 MV linear accelerator and evaluated using a Delta4 dosimeter. Results: The automated treatment planning method yielded clinically viable plans for all patients. The MR-CT fusion based dose calculation accuracy was within 2% as compared to calculations performed with original CT data. The dynamic T2-weighted TSE MR Sequence was able to provide an update of the anatomical location of the TV every 10 seconds. Dose calculation and optimization of the automatically generated treatment plans using only one GPU took on average 8 minutes. The Delta4 measurement of the irradiated plan agreed with the dose calculation with a 3%/3mm gamma pass rate of 86.4%. Conclusions: The development of an MR accelerator-enabled planning-todelivery technique for stereotactic palliative radiotherapy treatment of spinal metastases was presented. Future work will involve developing an intrafraction motion adaptation strategy, MR-only dose calculation, radiotherapy quality-assurance in a magnetic field, and streamlining the entire

  11. Accelerators, Beams And Physical Review Special Topics - Accelerators And Beams

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Siemann, R.H.; /SLAC

    Accelerator science and technology have evolved as accelerators became larger and important to a broad range of science. Physical Review Special Topics - Accelerators and Beams was established to serve the accelerator community as a timely, widely circulated, international journal covering the full breadth of accelerators and beams. The history of the journal and the innovations associated with it are reviewed.

  12. Commnity Petascale Project for Accelerator Science And Simulation: Advancing Computational Science for Future Accelerators And Accelerator Technologies

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Spentzouris, Panagiotis; /Fermilab; Cary, John

    The design and performance optimization of particle accelerators are essential for the success of the DOE scientific program in the next decade. Particle accelerators are very complex systems whose accurate description involves a large number of degrees of freedom and requires the inclusion of many physics processes. Building on the success of the SciDAC-1 Accelerator Science and Technology project, the SciDAC-2 Community Petascale Project for Accelerator Science and Simulation (ComPASS) is developing a comprehensive set of interoperable components for beam dynamics, electromagnetics, electron cooling, and laser/plasma acceleration modelling. ComPASS is providing accelerator scientists the tools required to enable the necessarymore » accelerator simulation paradigm shift from high-fidelity single physics process modeling (covered under SciDAC1) to high-fidelity multiphysics modeling. Our computational frameworks have been used to model the behavior of a large number of accelerators and accelerator R&D experiments, assisting both their design and performance optimization. As parallel computational applications, the ComPASS codes have been shown to make effective use of thousands of processors.« less

  13. Dynamic-MLC leaf control utilizing on-flight intensity calculations: a robust method for real-time IMRT delivery over moving rigid targets.

    PubMed

    McMahon, Ryan; Papiez, Lech; Rangaraj, Dharanipathy

    2007-08-01

    An algorithm is presented that allows for the control of multileaf collimation (MLC) leaves based entirely on real-time calculations of the intensity delivered over the target. The algorithm is capable of efficiently correcting generalized delivery errors without requiring the interruption of delivery (self-correcting trajectories), where a generalized delivery error represents anything that causes a discrepancy between the delivered and intended intensity profiles. The intensity actually delivered over the target is continually compared to its intended value. For each pair of leaves, these comparisons are used to guide the control of the following leaf and keep this discrepancy below a user-specified value. To demonstrate the basic principles of the algorithm, results of corrected delivery are shown for a leading leaf positional error during dynamic-MLC (DMLC) IMRT delivery over a rigid moving target. It is then shown that, with slight modifications, the algorithm can be used to track moving targets in real time. The primary results of this article indicate that the algorithm is capable of accurately delivering DMLC IMRT over a rigid moving target whose motion is (1) completely unknown prior to delivery and (2) not faster than the maximum MLC leaf velocity over extended periods of time. These capabilities are demonstrated for clinically derived intensity profiles and actual tumor motion data, including situations when the target moves in some instances faster than the maximum admissible MLC leaf velocity. The results show that using the algorithm while calculating the delivered intensity every 50 ms will provide a good level of accuracy when delivering IMRT over a rigid moving target translating along the direction of MLC leaf travel. When the maximum velocities of the MLC leaves and target were 4 and 4.2 cm/s, respectively, the resulting error in the two intensity profiles used was 0.1 +/- 3.1% and -0.5 +/- 2.8% relative to the maximum of the intensity profiles

  14. Fermilab | Tevatron | Accelerator

    Science.gov Websites

    Leading accelerator technology Accelerator complex Illinois Accelerator Research Center Fermilab temperature. They were used to transfer particles from one part of the Fermilab accelerator complex to another center ring of Fermilab's accelerator complex. Before the Tevatron shut down, it had three primary

  15. Dosimetric feasibility of magnetic resonance imaging-guided tri-cobalt 60 preoperative intensity modulated radiation therapy for soft tissue sarcomas of the extremity.

    PubMed

    Kishan, Amar U; Cao, Minsong; Mikaeilian, Argin G; Low, Daniel A; Kupelian, Patrick A; Steinberg, Michael L; Kamrava, Mitchell

    2015-01-01

    The purpose of this study was to investigate the dosimetric differences of delivering preoperative intensity modulated radiation therapy (IMRT) to patients with soft tissue sarcomas of the extremity (ESTS) with a teletherapy system equipped with 3 rotating (60)Co sources and a built-in magnetic resonance imaging and with standard linear accelerator (LINAC)-based IMRT. The primary study population consisted of 9 patients treated with preoperative radiation for ESTS between 2008 and 2014 with LINAC-based static field IMRT. LINAC plans were designed to deliver 50 Gy in 25 fractions to 95% of the planning target volume (PTV). Tri-(60)Co system IMRT plans were designed with ViewRay system software. Tri-(60)Co-based IMRT plans achieved equivalent target coverage and dosimetry for organs at risk (long bone, skin, and skin corridor) compared with LINAC-based IMRT plans. The maximum and minimum PTV doses, heterogeneity indices, and ratio of the dose to 50% of the volume were equivalent for both planning systems. One LINAC plan violated the maximum bone dose constraint, whereas none of the tri-(60)Co plans did. Using a tri-(60)Co system, we were able to achieve equivalent dosimetry to the PTV and organs at risk for patients with ESTS compared with LINAC-based IMRT plans. The tri-(60)Co system may be advantageous over current treatment platforms by allowing PTV reduction and by elimination of the additional radiation dose associated with daily image guidance, but this needs to be evaluated prospectively. Copyright © 2015 American Society for Radiation Oncology. Published by Elsevier Inc. All rights reserved.

  16. Piezoelectric particle accelerator

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kemp, Mark A.; Jongewaard, Erik N.; Haase, Andrew A.

    2017-08-29

    A particle accelerator is provided that includes a piezoelectric accelerator element, where the piezoelectric accelerator element includes a hollow cylindrical shape, and an input transducer, where the input transducer is disposed to provide an input signal to the piezoelectric accelerator element, where the input signal induces a mechanical excitation of the piezoelectric accelerator element, where the mechanical excitation is capable of generating a piezoelectric electric field proximal to an axis of the cylindrical shape, where the piezoelectric accelerator is configured to accelerate a charged particle longitudinally along the axis of the cylindrical shape according to the piezoelectric electric field.

  17. EDITORIAL: Laser and plasma accelerators Laser and plasma accelerators

    NASA Astrophysics Data System (ADS)

    Bingham, Robert

    2009-02-01

    This special issue on laser and plasma accelerators illustrates the rapid advancement and diverse applications of laser and plasma accelerators. Plasma is an attractive medium for particle acceleration because of the high electric field it can sustain, with studies of acceleration processes remaining one of the most important areas of research in both laboratory and astrophysical plasmas. The rapid advance in laser and accelerator technology has led to the development of terawatt and petawatt laser systems with ultra-high intensities and short sub-picosecond pulses, which are used to generate wakefields in plasma. Recent successes include the demonstration by several groups in 2004 of quasi-monoenergetic electron beams by wakefields in the bubble regime with the GeV energy barrier being reached in 2006, and the energy doubling of the SLAC high-energy electron beam from 42 to 85 GeV. The electron beams generated by the laser plasma driven wakefields have good spatial quality with energies ranging from MeV to GeV. A unique feature is that they are ultra-short bunches with simulations showing that they can be as short as a few femtoseconds with low-energy spread, making these beams ideal for a variety of applications ranging from novel high-brightness radiation sources for medicine, material science and ultrafast time-resolved radiobiology or chemistry. Laser driven ion acceleration experiments have also made significant advances over the last few years with applications in laser fusion, nuclear physics and medicine. Attention is focused on the possibility of producing quasi-mono-energetic ions with energies ranging from hundreds of MeV to GeV per nucleon. New acceleration mechanisms are being studied, including ion acceleration from ultra-thin foils and direct laser acceleration. The application of wakefields or beat waves in other areas of science such as astrophysics and particle physics is beginning to take off, such as the study of cosmic accelerators considered

  18. Source-to-accelerator quadrupole matching section for a compact linear accelerator

    NASA Astrophysics Data System (ADS)

    Seidl, P. A.; Persaud, A.; Ghiorso, W.; Ji, Q.; Waldron, W. L.; Lal, A.; Vinayakumar, K. B.; Schenkel, T.

    2018-05-01

    Recently, we presented a new approach for a compact radio-frequency (RF) accelerator structure and demonstrated the functionality of the individual components: acceleration units and focusing elements. In this paper, we combine these units to form a working accelerator structure: a matching section between the ion source extraction grids and the RF-acceleration unit and electrostatic focusing quadrupoles between successive acceleration units. The matching section consists of six electrostatic quadrupoles (ESQs) fabricated using 3D-printing techniques. The matching section enables us to capture more beam current and to match the beam envelope to conditions for stable transport in an acceleration lattice. We present data from an integrated accelerator consisting of the source, matching section, and an ESQ doublet sandwiched between two RF-acceleration units.

  19. A Dosimetric Evaluation of The Eclipse and Pinnacle Treatment Planning Systems in Treatment of Vertebral Bodies Using IMRT and VMAT with Modeled and Commissioned Flattening Filter Free (FFF) Fields

    NASA Astrophysics Data System (ADS)

    Ajo, Ramzi, Jr.

    generated and then delivered, using a Varian Edge linear accelerator, to a 4D QA phantom for a gamma analysis and distance to agreement (DTA) comparison. All Eclipse calculations were made for both measured and optimized DLG parameters. Calculated vs. measured point dose for the Pinnacle TPS had an average difference of 2.79 +/- 2.00%. Gamma analysis using a 3% and 3 mm DTA had 99/100 fields passing at > 95%. Using measured values of the DLG in Eclipse, calculated vs. measured point dose was -4.44 +/- 1.97%, and DTA had 33/110 fields passing at > 95%. After an optimization of the DLG in Eclipse, calculated vs. measured point dose had an average difference of 2.20 +/- 2.23%, and DTA with 95/110 fields passing at > 95%. This study looked at the performance of the Pinnacle and Eclipse TPS's, with special consideration given to the DLG parameterization used by Eclipse. The results support the idea that a single valued DLG is not sufficient for dynamic delivery. An optimization of the parameter is necessary to account for the high modulation of IMRT and VMAT techniques.

  20. SU-F-J-156: The Feasibility of MR-Only IMRT Planning for Prostate Anatomy

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Vaitheeswaran, R; Sivaramakrishnan, KR; Kumar, Prashant

    Purpose: For prostate anatomy, previous investigations have shown that simulated CT (sCT) generated from MR images can be used for accurate dose computation. In this study, we demonstrate the feasibility of MR-only IMRT planning for prostate case. Methods: Regular CT (rCT) and MR images of the same patient were acquired for prostate anatomy. Regions-of-interest (ROIs) i.e. target and risk structures are delineated on the rCT. A simulated CT (sCT) is generated from the MR image using the method described by Schadewaldt N et al. Their work establishes the clinical acceptability of dose calculation results on the sCT when compared tomore » rCT. rCT and sCT are rigidly registered to ensure proper alignment between the two images. rCT and sCT are overlaid on each other and slice-wise visual inspection confirms excellent agreement between the two images. ROIs on the rCT are copied over to sCT. Philips AutoPlanning solution is used for generating treatment plans. The same treatment technique protocol (plan parameters and clinical goals) is used to generate AutoPlan-rCT and AutoPlan-sCT respectively for rCT and and sCT. DVH comparison on ROIs and slice-wise evaluation of dose is performed between AutoPlan-rCT and AutoPlan-sCT. Delivery parameters i.e. beam and corresponding segments from the AutoPlan-sCT are copied over to rCT and dose is computed to get AutoPlan-sCT-on-rCT. Results: Plan evaluation is done based on Dose Volume Histogram (DVH) of ROIs and manual slice-wise inspection of dose distribution. Both AutoPlan-rCT and AutoPlan-sCT provide a clinically acceptable plan. Also, AutoPlan-sCT-on-rCT shows excellent agreement with AutoPlan-sCT. Conclusion: The study demonstrates that it is feasible to do IMRT planning on the simulated CT image obtained from MR image for prostate anatomy. The research is supported by Philips India Ltd.« less