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Sample records for dose guided radiotherapy

  1. Testicular Doses in Image-Guided Radiotherapy of Prostate Cancer

    SciTech Connect

    Deng Jun; Chen Zhe; Yu, James B.; Roberts, Kenneth B.; Peschel, Richard E.; Nath, Ravinder

    2012-01-01

    Purpose: To investigate testicular doses contributed by kilovoltage cone-beam computed tomography (kVCBCT) during image-guided radiotherapy (IGRT) of prostate cancer. Methods and Materials: An EGS4 Monte Carlo code was used to calculate three-dimensional dose distributions from kVCBCT on 3 prostate cancer patients. Absorbed doses to various organs were compared between intensity-modulated radiotherapy (IMRT) treatments and kVCBCT scans. The impact of CBCT scanning mode, kilovoltage peak energy (kVp), and CBCT field span on dose deposition to testes and other organs was investigated. Results: In comparison with one 10-MV IMRT treatment, a 125-kV half-fan CBCT scan delivered 3.4, 3.8, 4.1, and 5.7 cGy to the prostate, rectum, bladder, and femoral heads, respectively, accounting for 1.7%, 3.2%, 3.2%, and 8.4% of megavoltage photon dose contributions. However, the testes received 2.9 cGy from the same CBCT scan, a threefold increase as compared with 0.7 cGy received during IMRT. With the same kVp, full-fan mode deposited much less dose to organs than half-fan mode, ranging from 9% less for prostate to 69% less for testes, except for rectum, where full-fan mode delivered 34% more dose. As photon beam energy increased from 60 to 125 kV, kVCBCT-contributed doses increased exponentially for all organs, irrespective of scanning mode. Reducing CBCT field span from 30 to 10 cm in the superior-inferior direction cut testicular doses from 5.7 to 0.2 cGy in half-fan mode and from 1.5 to 0.1 cGy in full-fan mode. Conclusions: Compared with IMRT, kVCBCT-contributed doses to the prostate, rectum, bladder, and femoral heads are clinically insignificant, whereas dose to the testes is threefold more. Full-fan CBCT usually deposits much less dose to organs (except for rectum) than half-fan mode in prostate patients. Kilovoltage CBCT-contributed doses increase exponentially with photon beam energy. Reducing CBCT field significantly cuts doses to testes and other organs.

  2. Normal tissue dose conformality measures to guide radiotherapy fractionation decisions

    SciTech Connect

    Myerson, Robert J.

    2011-04-15

    Purpose: To determine conditions under which hypofractionation could be favorable for a normal tissue--even if tumor [{alpha}/{beta}] exceeds the normal tissue's [{alpha}/{beta}]. Methods: The hypofractionation sufficiency condition (HSC) for an organ is defined as a dose conformality constraint such that, if satisfied, a family of tumor control probability isoeffective fractionation schemes will show decreasing normal tissue complication probability with decreasing number of fractions. Results: In the extended equivalent uniform dose (EUD) model [obtained by replacing dose with linear quadratic (LQ) 2 Gy equivalent dose], the HSC for a normal organ is proven to be satisfied if a suitably weighted average of the relative dose [hypofractionation sufficiency index (HSI)] is less than the ratio of normal tissue to tumor [{alpha}/{beta}]. The HSI is determined solely by dose distribution and the normal tissue volume factor, ''a.'' If the HSC is satisfied for every normal tissue of concern, then there is a therapeutic gain with hypofractionation. The corresponding multifractionation sufficiency condition (therapeutic gain with increasing number of fractions) and multifractionation sufficiency index (MSI) are also derived. A sample clinical case is presented. Conclusions: Within the context of the LQ/EUD models, conformality measures (HSI and MSI) can be used to inform fractionation decisions.

  3. Radiation Dose From Kilovoltage Cone Beam Computed Tomography in an Image-Guided Radiotherapy Procedure

    SciTech Connect

    Ding, George X. Coffey, Charles W.

    2009-02-01

    Purpose: Image-guided radiation therapy has emerged as the new paradigm in radiotherapy. This work is to provide detailed information concerning the additional imaging doses to patients' radiosensitive organs from a kilovoltage cone beam computed tomography (kV CBCT) scan procedure. Methods and Materials: The Vanderbilt-Monte-Carlo-Beam-Calibration (VMCBC; Vanderbilt University, Nashville, TN) algorithm was used to calculate radiation dose to organs resulting from a kV CBCT imaging guidance procedure. Eight patients, including 3 pediatric and 5 adult patients, were investigated. The CBCT scans in both full- and half-fan modes were studied. Results: For a head-and-neck scan in half-fan mode, dose-volume histogram analyses show mean doses of 7 and 8 cGy to the eyes, 5 and 6 cGy to the spinal cord, 5 and 6 cGy to the brain, and 18 and 23 cGy to the cervical vertebrae for an adult and a 29-month-old child, respectively. The dose from a scan in full-fan mode is 10-20% lower than that in half-fan mode. For an abdominal scan, mean doses are 3 and 7 cGy to prostate and 7 and 17 cGy to femoral heads for a large adult patient and a 31-month-old pediatric patient, respectively. Conclusions: Doses to radiosensitive organs can total 300 cGy accrued over an entire treatment course if kV CBCT scans are acquired daily. These findings provide needed data for clinicians to make informed decisions concerning additional imaging doses. The dose to bone is two to four times greater than dose to soft tissue for kV x-rays, which should be considered, especially for pediatric patients.

  4. Clinical Outcome of Dose-Escalated Image-Guided Radiotherapy for Spinal Metastases

    SciTech Connect

    Guckenberger, Matthias; Goebel, Joachim; Wilbert, Juergen; Baier, Kurt; Richter, Anne; Sweeney, Reinhart A.; Bratengeier, Klaus; Flentje, Michael

    2009-11-01

    Purpose: To evaluate the outcomes after dose-escalated radiotherapy (RT) for spinal metastases and paraspinal tumors. Methods and Materials: A total of 14 patients, 12 with spinal metastases and a long life expectancy and 2 with paraspinal tumors, were treated for 16 lesions with intensity-modulated, image-guided RT. A median biologic effective dose of 74 Gy{sub 10} (range, 55-86) in a median of 20 fractions (range, 3-34) was prescribed to the target volume. The spinal canal was treated to 40 Gy in 20 fractions using a second intensity-modulated RT dose level in the case of epidural involvement. Results: After median follow-up of 17 months, one local recurrence was observed, for an actuarial local control rate of 88% after 2 years. Local control was associated with rapid and long-term pain relief. Of 11 patients treated for a solitary spinal metastasis, 6 developed systemic disease progression. The actuarial overall survival rate for metastatic patients was 85% and 63% after 1 and 2 years, respectively. Acute Grade 2-3 skin toxicity was seen in 2 patients with no late toxicity greater than Grade 2. No radiation-induced myelopathy was observed. Conclusion: Dose-escalated irradiation of spinal metastases was safe and resulted in excellent local control. Oligometastatic patients with a long life expectancy and epidural involvement are considered to benefit the most from fractionated RT.

  5. MR-guided breast radiotherapy: feasibility and magnetic-field impact on skin dose

    NASA Astrophysics Data System (ADS)

    van Heijst, Tristan C. F.; den Hartogh, Mariska D.; Lagendijk, Jan J. W.; Desirée van den Bongard, H. J. G.; van Asselen, Bram

    2013-09-01

    The UMC Utrecht MRI/linac (MRL) design provides image guidance with high soft-tissue contrast, directly during radiotherapy (RT). Breast cancer patients are a potential group to benefit from better guidance in the MRL. However, due to the electron return effect, the skin dose can be increased in presence of a magnetic field. Since large skin areas are generally involved in breast RT, the purpose of this study is to investigate the effects on the skin dose, for whole-breast irradiation (WBI) and accelerated partial-breast irradiation (APBI). In ten patients with early-stage breast cancer, targets and organs at risk (OARs) were delineated on postoperative CT scans co-registered with MRI. The OARs included the skin, comprising the first 5 mm of ipsilateral-breast tissue, plus extensions. Three intensity-modulated RT techniques were considered (2× WBI, 1× APBI). Individual beam geometries were used for all patients. Specially developed MRL treatment-planning software was used. Acceptable plans were generated for 0 T, 0.35 T and 1.5 T, using a class solution. The skin dose was augmented in WBI in the presence of a magnetic field, which is a potential drawback, whereas in APBI the induced effects were negligible. This opens possibilities for developing MR-guided partial-breast treatments in the MRL.

  6. Dose-Response Relationship for Image-Guided Stereotactic Body Radiotherapy of Pulmonary Tumors: Relevance of 4D Dose Calculation

    SciTech Connect

    Guckenberger, Matthias Wulf, Joern; Mueller, Gerd; Krieger, Thomas; Baier, Kurt; Gabor, Manuela; Richter, Anne; Wilbert, Juergen; Flentje, Michael

    2009-05-01

    Purpose: To evaluate outcome after image-guided stereotactic body radiotherapy (SBRT) for early-stage non-small-cell lung cancer (NSCLC) and pulmonary metastases. Methods and Materials: A total of 124 patients with 159 pulmonary lesions (metastases n = 118; NSCLC, n = 41; Stage IA, n = 13; Stage IB, n = 19; T3N0, n = 9) were treated with SBRT. Patients were treated with hypofractionated schemata (one to eight fractions of 6-26 Gy); biologic effective doses (BED) to the clinical target volume (CTV) were calculated based on four-dimensional (4D) dose calculation. The position of the pulmonary target was verified using volume imaging before all treatments. Results: With mean/median follow-up of 18/14 months, actuarial local control was 83% at 36 months with no difference between NSCLC and metastases. The dose to the CTV based on 4D dose calculation was closely correlated with local control: local control rates were 89% and 62% at 36 months for >100 Gy and <100 Gy BED (p = 0.0001), respectively. Actuarial freedom from regional and systemic progression was 34% at 36 months for primary NSCLC group; crude rate of regional failure was 15%. Three-year overall survival was 37% for primary NSCLC and 16% for metastases; no dose-response relationship for survival was observed. Exacerbation of comorbidities was the most frequent cause of death for primary NSCLC. Conclusions: Doses of >100 Gy BED to the CTV based on 4D dose calculation resulted in excellent local control rates. This cutoff dose is not specific to the treatment technique and protocol of our study and may serve as a general recommendation.

  7. The management of imaging dose during image-guided radiotherapy: Report of the AAPM Task Group 75

    SciTech Connect

    Murphy, Martin J.; Balter, James; Balter, Stephen; BenComo, Jose A. Jr.; Das, Indra J.; Jiang, Steve B.; Ma, C.-M.; Olivera, Gustavo H.; Rodebaugh, Raymond F.; Ruchala, Kenneth J.; Shirato, Hiroki; Yin, Fang-Fang

    2007-10-15

    Radiographic image guidance has emerged as the new paradigm for patient positioning, target localization, and external beam alignment in radiotherapy. Although widely varied in modality and method, all radiographic guidance techniques have one thing in common--they can give a significant radiation dose to the patient. As with all medical uses of ionizing radiation, the general view is that this exposure should be carefully managed. The philosophy for dose management adopted by the diagnostic imaging community is summarized by the acronym ALARA, i.e., as low as reasonably achievable. But unlike the general situation with diagnostic imaging and image-guided surgery, image-guided radiotherapy (IGRT) adds the imaging dose to an already high level of therapeutic radiation. There is furthermore an interplay between increased imaging and improved therapeutic dose conformity that suggests the possibility of optimizing rather than simply minimizing the imaging dose. For this reason, the management of imaging dose during radiotherapy is a different problem than its management during routine diagnostic or image-guided surgical procedures. The imaging dose received as part of a radiotherapy treatment has long been regarded as negligible and thus has been quantified in a fairly loose manner. On the other hand, radiation oncologists examine the therapy dose distribution in minute detail. The introduction of more intensive imaging procedures for IGRT now obligates the clinician to evaluate therapeutic and imaging doses in a more balanced manner. This task group is charged with addressing the issue of radiation dose delivered via image guidance techniques during radiotherapy. The group has developed this charge into three objectives: (1) Compile an overview of image-guidance techniques and their associated radiation dose levels, to provide the clinician using a particular set of image guidance techniques with enough data to estimate the total diagnostic dose for a specific

  8. Positron Emission Tomography-Guided, Focal-Dose Escalation Using Intensity-Modulated Radiotherapy for Head and Neck Cancer

    SciTech Connect

    Madani, Indira . E-mail: indira@krtkg1.ugent.be; Duthoy, Wim; Derie, Cristina R.N.; De Gersem, Werner Ir.; Boterberg, Tom; Saerens, Micky; Jacobs, Filip Ir.; Gregoire, Vincent; Lonneux, Max; Vakaet, Luc; Vanderstraeten, Barbara; Bauters, Wouter; Bonte, Katrien; Thierens, Hubert; Neve, Wilfried de

    2007-05-01

    Purpose: To assess the feasibility of intensity-modulated radiotherapy (IMRT) using positron emission tomography (PET)-guided dose escalation, and to determine the maximum tolerated dose in head and neck cancer. Methods and Materials: A Phase I clinical trial was designed to escalate the dose limited to the [{sup 18}-F]fluoro-2-deoxy-D-glucose positron emission tomography ({sup 18}F-FDG-PET)-delineated subvolume within the gross tumor volume. Positron emission tomography scanning was performed in the treatment position. Intensity-modulated radiotherapy with an upfront simultaneously integrated boost was employed. Two dose levels were planned: 25 Gy (level I) and 30 Gy (level II), delivered in 10 fractions. Standard IMRT was applied for the remaining 22 fractions of 2.16 Gy. Results: Between 2003 and 2005, 41 patients were enrolled, with 23 at dose level I, and 18 at dose level II; 39 patients completed the planned therapy. The median follow-up for surviving patients was 14 months. Two cases of dose-limiting toxicity occurred at dose level I (Grade 4 dermitis and Grade 4 dysphagia). One treatment-related death at dose level II halted the study. Complete response was observed in 18 of 21 (86%) and 13 of 16 (81%) evaluated patients at dose levels I and II (p < 0.7), respectively, with actuarial 1-year local control at 85% and 87% (p n.s.), and 1-year overall survival at 82% and 54% (p = 0.06), at dose levels I and II, respectively. In 4 of 9 patients, the site of relapse was in the boosted {sup 18}F-FDG-PET-delineated region. Conclusions: For head and neck cancer, PET-guided dose escalation appears to be well-tolerated. The maximum tolerated dose was not reached at the investigated dose levels.

  9. Dosimetric evaluation of the OneDose MOSFET for measuring kilovoltage imaging dose from image-guided radiotherapy procedures

    SciTech Connect

    Ding, George X.; Coffey, Charles W.

    2010-09-15

    Purpose: The purpose of this study is to investigate the feasibility of using a single-use dosimeter, OneDose MOSFET designed for in vivo patient dosimetry, for measuring the radiation dose from kilovoltage (kV) x rays resulting from image-guided procedures. Methods: The OneDose MOSFET dosimeters were precalibrated by the manufacturer using Co-60 beams. Their energy response and characteristics for kV x rays were investigated by using an ionization chamber, in which the air-kerma calibration factors were obtained from an Accredited Dosimetry Calibration Laboratory (ADCL). The dosimetric properties have been tested for typical kV beams used in image-guided radiation therapy (IGRT). Results: The direct dose reading from the OneDose system needs to be multiplied by a correction factor ranging from 0.30 to 0.35 for kilovoltage x rays ranging from 50 to 125 kVp, respectively. In addition to energy response, the OneDose dosimeter has up to a 20% reduced sensitivity for beams (70-125 kVp) incident from the back of the OneDose detector. Conclusions: The uncertainty in measuring dose resulting from a kilovoltage beam used in IGRT is approximately 20%; this uncertainty is mainly due to the sensitivity dependence of the incident beam direction relative to the OneDose detector. The ease of use may allow the dosimeter to be suitable for estimating the dose resulting from image-guided procedures.

  10. SU-E-J-198: Out-Of-Field Dose and Surface Dose Measurements of MRI-Guided Cobalt-60 Radiotherapy

    SciTech Connect

    Lamb, J; Agazaryan, N; Cao, M; Low, D; Thomas, D; Yang, Y

    2015-06-15

    Purpose: To measure quantities of dosimetric interest in an MRI-guided cobalt radiotherapy machine that was recently introduced to clinical use. Methods: Out-of-field dose due to photon scatter and leakage was measured using an ion chamber and solid water slabs mimicking a human body. Surface dose was measured by irradiating stacks of radiochromic film and extrapolating to zero thickness. Electron out-of-field dose was characterized using solid water slabs and radiochromic film. Results: For some phantom geometries, up to 50% of Dmax was observed up to 10 cm laterally from the edge of the beam. The maximum penetration was between 1 and 2 mm in solid water, indicating an electron energy not greater than approximately 0.4 MeV. Out-of-field dose from photon scatter measured at 1 cm depth in solid water was found to fall to less than 10% of Dmax at a distance of 1.2 cm from the edge of a 10.5 × 10.5 cm field, and less that 1% of Dmax at a distance of 10 cm from field edge. Surface dose was measured to be 8% of Dmax. Conclusion: Surface dose and out-of-field dose from the MRIguided cobalt radiotherapy machine was measured and found to be within acceptable limits. Electron out-of-field dose, an effect unique to MRI-guided radiotherapy and presumed to arise from low-energy electrons trapped by the Lorentz force, was quantified. Dr. Low is a member of the scientific advisory board of ViewRay, Inc.

  11. Predictors of Local Control After Single-Dose Stereotactic Image-Guided Intensity-Modulated Radiotherapy for Extracranial Metastases

    SciTech Connect

    Greco, Carlo; Zelefsky, Michael J.; Lovelock, Michael; Fuks, Zvi; Hunt, Margie; Rosenzweig, Kenneth; Zatcky, Joan; Kim, Balem; Yamada, Yoshiya

    2011-03-15

    Purpose: To report tumor local control after treatment with single-dose image-guided intensity-modulated radiotherapy (SD-IGRT) to extracranial metastatic sites. Methods and Materials: A total of 126 metastases in 103 patients were treated with SD-IGRT to prescription doses of 18-24 Gy (median, 24 Gy) between 2004 and 2007. Results: The overall actuarial local relapse-free survival (LRFS) rate was 64% at a median follow-up of 18 months (range, 2-45 months). The median time to failure was 9.6 months (range, 1-23 months). On univariate analysis, LRFS was significantly correlated with prescription dose (p = 0.029). Stratification by dose into high (23 to 24 Gy), intermediate (21 to 22 Gy), and low (18 to 20 Gy) dose levels revealed highly significant differences in LRFS between high (82%) and low doses (25%) (p < 0.0001). Overall, histology had no significant effect on LRFS (p = 0.16). Renal cell histology displayed a profound dose-response effect, with 80% LRFS at the high dose level (23 to 24 Gy) vs. 37% with low doses ({<=}22 Gy) (p = 0.04). However, for patients who received the high dose level, histology was not a statistically significant predictor of LRFS (p = 0.90). Target organ (bone vs. lymph node vs. soft tissues) (p = 0.5) and planning target volume size (p = 0.55) were not found to be associated with long-term LRFS probability. Multivariate Cox regression analysis confirmed prescription dose to be a significant predictor of LRFS (p = 0.003). Conclusion: High-dose SD-IGRT is a noninvasive procedure resulting in high probability of local tumor control. Single-dose IGRT may be effectively used to locally control metastatic deposits regardless of histology and target organ, provided sufficiently high doses (> 22 Gy) of radiation are delivered.

  12. Tumor Control Outcomes After Hypofractionated and Single-Dose Stereotactic Image-Guided Intensity-Modulated Radiotherapy for Extracranial Metastases From Renal Cell Carcinoma

    SciTech Connect

    Zelefsky, Michael J.; Greco, Carlo; Motzer, Robert; Magsanoc, Juan Martin; Pei Xin; Lovelock, Michael; Mechalakos, Jim; Zatcky, Joan; Fuks, Zvi; Yamada, Yoshiya

    2012-04-01

    Purpose: To report tumor local progression-free outcomes after treatment with single-dose, image-guided, intensity-modulated radiotherapy and hypofractionated regimens for extracranial metastases from renal cell primary tumors. Patients and Methods: Between 2004 and 2010, 105 lesions from renal cell carcinoma were treated with either single-dose, image-guided, intensity-modulated radiotherapy to a prescription dose of 18-24 Gy (median, 24) or hypofractionation (three or five fractions) with a prescription dose of 20-30 Gy. The median follow-up was 12 months (range, 1-48). Results: The overall 3-year actuarial local progression-free survival for all lesions was 44%. The 3-year local progression-free survival for those who received a high single-dose (24 Gy; n = 45), a low single-dose (<24 Gy; n = 14), or hypofractionation regimens (n = 46) was 88%, 21%, and 17%, respectively (high single dose vs. low single dose, p = .001; high single dose vs. hypofractionation, p < .001). Multivariate analysis revealed the following variables were significant predictors of improved local progression-free survival: 24 Gy dose compared with a lower dose (p = .009) and a single dose vs. hypofractionation (p = .008). Conclusion: High single-dose, image-guided, intensity-modulated radiotherapy is a noninvasive procedure resulting in high probability of local tumor control for metastatic renal cell cancer generally considered radioresistant according to the classic radiobiologic ranking.

  13. High-Dose, Single-Fraction Image-Guided Intensity-Modulated Radiotherapy for Metastatic Spinal Lesions

    SciTech Connect

    Yamada, Yoshiya Bilsky, Mark H.; Lovelock, D. Michael; Venkatraman, Ennapadam S.; Toner, Sean; Johnson, Jared; Zatcky, Joan N.P.; Zelefsky, Michael J.; Fuks, Zvi

    2008-06-01

    Purpose: To report tumor control and toxicity for patients treated with image-guided intensity-modulated radiotherapy (RT) for spinal metastases with high-dose single-fraction RT. Methods and Materials: A total of 103 consecutive spinal metastases in 93 patients without high-grade epidural spinal cord compression were treated with image-guided intensity-modulated RT to doses of 18-24 Gy (median, 24 Gy) in a single fraction between 2003 and 2006. The spinal cord dose was limited to a 14-Gy maximal dose. The patients were prospectively examined every 3-4 months with clinical assessment and cross-sectional imaging. Results: The overall actuarial local control rate was 90% (local failure developed in 7 patients) at a median follow-up of 15 months (range, 2-45 months). The median time to local failure was 9 months (range, 2-15 months) from the time of treatment. Of the 93 patients, 37 died. The median overall survival was 15 months. In all cases, death was from progression of systemic disease and not local failure. The histologic type was not a statistically significant predictor of survival or local control. The radiation dose was a significant predictor of local control (p = 0.03). All patients without local failure also reported durable symptom palliation. Acute toxicity was mild (Grade 1-2). No case of radiculopathy or myelopathy has developed. Conclusion: High-dose, single-fraction image-guided intensity-modulated RT is a noninvasive intervention that appears to be safe and very effective palliation for patients with spinal metastases, with minimal negative effects on quality of life and a high probability of tumor control.

  14. Magnetic-field-induced dose effects in MR-guided radiotherapy systems: dependence on the magnetic field strength

    NASA Astrophysics Data System (ADS)

    Raaijmakers, A. J. E.; Raaymakers, B. W.; Lagendijk, J. J. W.

    2008-02-01

    Several institutes are currently working on the development of a radiotherapy treatment system with online MR imaging (MRI) modality. The main difference between their designs is the magnetic field strength of the MRI system. While we have chosen a 1.5 Tesla (T) magnetic field strength, the Cross Cancer Institute in Edmonton will be using a 0.2 T MRI scanner and the company Viewray aims to use 0.3 T. The magnetic field strength will affect the severity of magnetic field dose effects, such as the electron return effect (ERE): considerable dose increase at tissue air boundaries due to returning electrons. This paper has investigated how the ERE dose increase depends on the magnetic field strength. Therefore, four situations where the ERE occurs have been simulated: ERE at the distal side of the beam, the lateral ERE, ERE in cylindrical air cavities and ERE in the lungs. The magnetic field comparison values were 0.2, 0.75, 1.5 and 3 T. Results show that, in general, magnetic field dose effects are reduced at lower magnetic field strengths. At the distal side, the ERE dose increase is largest for B = 0.75 T and depends on the irradiation field size for B = 0.2 T. The lateral ERE is strongest for B = 3 T but shows no effect for B = 0.2 T. Around cylindrical air cavities, dose inhomogeneities disappear if the radius of the cavity becomes small relative to the in-air radius of the secondary electron trajectories. At larger cavities (r > 1 cm), dose inhomogeneities exist for all magnetic field strengths. In water-lung-water phantoms, the ERE dose increase takes place at the water-lung transition and the dose decreases at the lung-water transition, but these effects are minimal for B = 0.2 T. These results will contribute to evaluating the trade-off between magnetic field dose effects and image quality of MR-guided radiotherapy systems.

  15. Patient-Specific Three-Dimensional Concomitant Dose From Cone Beam Computed Tomography Exposure in Image-Guided Radiotherapy

    SciTech Connect

    Spezi, Emiliano; Downes, Patrick; Jarvis, Richard; Radu, Emil; Staffurth, John

    2012-05-01

    Purpose: The purpose of the present study was to quantify the concomitant dose received by patients undergoing cone beam computed tomography (CBCT) scanning in different clinical scenarios as a part of image-guided radiotherapy (IGRT) procedures. Methods and Materials: We calculated the three-dimensional concomitant dose received as a result of CBCT scans in 6 patients representing different clinical scenarios: two pelvis, two head and neck, and two chest. We assessed the effect that a daily on-line IGRT strategy would have on the patient dose distribution, assuming 40 CBCT scans throughout the treatment course. The additional dose to the planning target volume margin region was also estimated. Results: In the pelvis, a single CBCT scan delivered a mean dose to the femoral heads of 2-6 cGy and the rectum of 1-2 cGy. An additional dose to the planning target volume was within 1-3 cGy. In the chest, the mean dose to the planning target volume varied from 2.5 to 5 cGy. The lung and spinal cord planning organ at risk volume received {<=}4 cGy and {<=}5 cGy, respectively. In the head and neck, a single CBCT scan delivered a mean dose of 0.3 cGy, with bony structures receiving 0.5-0.8 cGy. The femoral heads received an additional dose of 1.5-2.5 Gy. A reduction of 20-30% in the mean dose to the organs at risk was achieved using bowtie filtration. In the head and neck, the dose to the eyes and brainstem was eliminated by decreasing the craniocaudal field size. Conclusions: The additional dose from on-line IGRT procedures can be clinically relevant. The organ dose can be significantly reduced with the use of appropriate patient-specific settings. The concomitant dose from CBCT should be accounted for and the acquisition settings optimized for optimal IGRT strategies on a patient basis.

  16. SU-D-9A-07: Imaging Dose and Cancer Risk in Image-Guided Radiotherapy of Cancers

    SciTech Connect

    Zhou, L; Bai, S; Zhang, Y; Ming, X; Zhang, Y; Deng, J

    2014-06-01

    Purpose: To systematically evaluate the imaging doses and cancer risks associated with various imaging procedures involving ionizing radiation during image-guided radiotherapy of an increasingly large number of cancer patients. Methods: 141 patients (52 brain cases, 47 thoracic cases, 42 abdominal cases, aged 3 to 91 years old) treated between October 2009 and March 2010 were included in this IRB-approved retrospective study. During the whole radiotherapy course, each patient underwent at least one type of imaging procedures, i.e., kV portal, MV portal and kVCBCT, besides CT simulations. Based on Monte Carlo modeling and particle transport in human anatomy of various dimensions, the correlations between the radiation doses to the various organs-at-risk (OARs) at the head, the thoracic and the abdominal regions and one's weight, circumference, scan mAs and kVp have been obtained and used to estimate the radiation dose from a specific imaging procedure. The radiation-induced excess relative risk (ERR) was then estimated with BEIR VII formulism based on one's gender, age and radiation dose. 1+ ERR was reported in this study as relative cancer risk. Results: For the whole cohort of 141 patients, the mean imaging doses from various imaging procedures were 8.3 cGy to the brain, 10.5 cGy to the lungs and 19.2 cGy to the red bone marrow, respectively. Accordingly, the cancer risks were 1.140, 1.369 and 2.671, respectively. In comparison, MV portal deposited largest doses to the lungs while kVCBCT delivered the highest doses to the red bone marrow. Conclusion: The compiled imaging doses to a patient during his/her treatment course were patient-specific and site-dependent, varying from 1.2 to 263.5 cGy on average, which were clinically significant and should be included in the treatment planning and overall decision-making. Our results indicated the necessity of personalized imaging to maximize its clinical benefits while reducing the associated cancer risks. Sichuan

  17. Evaluations of an adaptive planning technique incorporating dose feedback in image-guided radiotherapy of prostate cancer

    SciTech Connect

    Liu Han; Wu Qiuwen

    2011-12-15

    treatment course, then 11 patients fail. If the same criteria is assessed at the end of each week (every five fractions), then 14 patients fail, with three patients failing the 1st or 2nd week but passing at the end. The average dose deficit from these 14 patients was 4.4%. They improved to 2% after the weekly compensation. Out of these 14 patients who needed dose compensation, ten passed the dose criterion after weekly dose compensation, three patients failed marginally, and one patient still failed the criterion significantly (10% deficit), representing 3.6% of the patient population. A more aggressive compensation frequency (every three fractions) could successfully reduce the dose deficit to the acceptable level for this patient. The average number of required dose compensation re-planning per patient was 0.82 (0.79) per patient for schedule A (B) delivery strategy. The doses to OARs were not significantly different from the online IG only plans without dose compensation. Conclusions: We have demonstrated the effectiveness of offline dose compensation technique in image-guided radiotherapy for prostate cancer. It can effectively account for residual uncertainties which cannot be corrected through online IG. Dose compensation allows further margin reduction and critical organs sparing.

  18. Personalized Assessment of kV Cone Beam Computed Tomography Doses in Image-guided Radiotherapy of Pediatric Cancer Patients

    SciTech Connect

    Zhang Yibao; Yan Yulong; Nath, Ravinder; Bao Shanglian; Deng Jun

    2012-08-01

    Purpose: To develop a quantitative method for the estimation of kV cone beam computed tomography (kVCBCT) doses in pediatric patients undergoing image-guided radiotherapy. Methods and Materials: Forty-two children were retrospectively analyzed in subgroups of different scanned regions: one group in the head-and-neck and the other group in the pelvis. Critical structures in planning CT images were delineated on an Eclipse treatment planning system before being converted into CT phantoms for Monte Carlo simulations. A benchmarked EGS4 Monte Carlo code was used to calculate three-dimensional dose distributions of kVCBCT scans with full-fan high-quality head or half-fan pelvis protocols predefined by the manufacturer. Based on planning CT images and structures exported in DICOM RT format, occipital-frontal circumferences (OFC) were calculated for head-and-neck patients using DICOMan software. Similarly, hip circumferences (HIP) were acquired for the pelvic group. Correlations between mean organ doses and age, weight, OFC, and HIP values were analyzed with SigmaPlot software suite, where regression performances were analyzed with relative dose differences (RDD) and coefficients of determination (R{sup 2}). Results: kVCBCT-contributed mean doses to all critical structures decreased monotonically with studied parameters, with a steeper decrease in the pelvis than in the head. Empirical functions have been developed for a dose estimation of the major organs at risk in the head and pelvis, respectively. If evaluated with physical parameters other than age, a mean RDD of up to 7.9% was observed for all the structures in our population of 42 patients. Conclusions: kVCBCT doses are highly correlated with patient size. According to this study, weight can be used as a primary index for dose assessment in both head and pelvis scans, while OFC and HIP may serve as secondary indices for dose estimation in corresponding regions. With the proposed empirical functions, it is possible

  19. On the use of an analytic source model for dose calculations in precision image-guided small animal radiotherapy

    NASA Astrophysics Data System (ADS)

    Granton, Patrick V.; Verhaegen, Frank

    2013-05-01

    Precision image-guided small animal radiotherapy is rapidly advancing through the use of dedicated micro-irradiation devices. However, precise modeling of these devices in model-based dose-calculation algorithms such as Monte Carlo (MC) simulations continue to present challenges due to a combination of very small beams, low mechanical tolerances on beam collimation, positioning and long calculation times. The specific intent of this investigation is to introduce and demonstrate the viability of a fast analytical source model (AM) for use in either investigating improvements in collimator design or for use in faster dose calculations. MC models using BEAMnrc were developed for circular and square fields sizes from 1 to 25 mm in diameter (or side) that incorporated the intensity distribution of the focal spot modeled after an experimental pinhole image. These MC models were used to generate phase space files (PSFMC) at the exit of the collimators. An AM was developed that included the intensity distribution of the focal spot, a pre-calculated x-ray spectrum, and the collimator-specific entrance and exit apertures. The AM was used to generate photon fluence intensity distributions (ΦAM) and PSFAM containing photons radiating at angles according to the focal spot intensity distribution. MC dose calculations using DOSXYZnrc in a water and mouse phantom differing only by source used (PSFMC versus PSFAM) were found to agree within 7% and 4% for the smallest 1 and 2 mm collimator, respectively, and within 1% for all other field sizes based on depth dose profiles. PSF generation times were approximately 1200 times faster for the smallest beam and 19 times faster for the largest beam. The influence of the focal spot intensity distribution on output and on beam shape was quantified and found to play a significant role in calculated dose distributions. Beam profile differences due to collimator alignment were found in both small and large collimators sensitive to shifts of 1

  20. SU-E-J-10: Imaging Dose and Cancer Risk in Image-Guided Radiotherapy of Cancers

    SciTech Connect

    Zhou, L; Bai, S; Zhang, Y; Deng, J

    2015-06-15

    Purpose: To systematically evaluate imaging doses and cancer risks to organs-at-risk as a Result of cumulative doses from various radiological imaging procedures in image-guided radiotherapy (IGRT) in a large cohort of cancer patients. Methods: With IRB approval, imaging procedures (computed tomography, kilo-voltage portal imaging, megavoltage portal imaging and kilo-voltage cone-beam computed tomography) of 4832 cancer patients treated during 4.5 years were collected with their gender, age and circumference. Correlations between patient’s circumference and Monte Carlo simulated-organ dose were applied to estimate organ doses while the cancer risks were reported as 1+ERR using BEIR VII models. Results: 80 cGy or more doses were deposited to brain, lungs and RBM in 273 patients (maximum 136, 278 and 267 cGy, respectively), due largely to repetitive imaging procedures and non-personalized imaging settings. Regardless of gender, relative cancer risk estimates for brain, lungs, and RBM were 3.4 (n = 55), 2.6 (n = 49), 1.8 (n = 25) for age group of 0–19; 1.2 (n = 87), 1.4 (n = 98), 1.3 (n = 51) for age group of 20–39; 1.0 (n = 457), 1.1 (n = 880), 1.8 (n=360) for age group of 40–59; 1.0 (n = 646), 1.1 (n = 1400), 2.3 (n = 716) for age group of 60–79 and 1.0 (n = 108),1.1 (n = 305),1.6 (n = 147) for age group of 80–99. Conclusion: The cumulative imaging doses and associated cancer risks from multi-imaging procedures were patient-specific and site-dependent, with up to 2.7 Gy imaging dose deposited to critical structures in some pediatric patients. The associated cancer risks in brain and lungs for children of age 0 to 19 were 2–3 times larger than those for adults. This study indicated a pressing need for personalized imaging protocol to maximize its clinical benefits while reducing associated cancer risks. Sichuan University Scholarship.

  1. Evaluation of Patient Doses from Verification Techniques in Image-Guided Radiotherapy (IGRT)

    SciTech Connect

    Dufek, Vladimir; Horakova, Ivana; Novak, Leos; Koncek, Ondrej; Richter, Vit; Janeckova, Lenka

    2010-01-05

    The purpose of this work was an evaluation of organ doses and effective doses from kilovoltage (kV) cone-beam CT (CBCT) scans and from pairs of orthogonal kV image projections for two different treatment sites (a head and a pelvis). Measurements of organ doses were performed in an anthropomorphic rando phantom by means of thermoluminescent dosimeters (TLDs). Irradiations were performed using on-board imager (OBI) and X-ray volume imaging (XVI) systems.

  2. Evaluation of Patient Doses from Verification Techniques in Image-Guided Radiotherapy (IGRT)

    NASA Astrophysics Data System (ADS)

    Dufek, Vladimir; Horakova, Ivana; Novak, Leos; Koncek, Ondrej; Richter, Vit; Janeckova, Lenka

    2010-01-01

    The purpose of this work was an evaluation of organ doses and effective doses from kilovoltage (kV) cone-beam CT (CBCT) scans and from pairs of orthogonal kV image projections for two different treatment sites (a head and a pelvis). Measurements of organ doses were performed in an anthropomorphic rando phantom by means of thermoluminescent dosimeters (TLDs). Irradiations were performed using on-board imager (OBI) and X-ray volume imaging (XVI) systems.

  3. Comparison of a simple dose-guided intervention technique for prostate radiotherapy with existing anatomical image guidance methods

    PubMed Central

    Smyth, G; Mccallum, H M; Pearson, M J M; Lawrence, G P

    2012-01-01

    Objectives A simple dose-guided intervention technique for prostate radiotherapy using an isodose overlay method combined with soft-tissue-based corrective couch shifts has been proposed previously. This planning study assesses the potential clinical impact of such a correction strategy. Methods 10 patients, each with 8–11 on-treatment CT studies (n=97), were assessed using this technique and compared with no intervention, bony anatomy intervention and soft-tissue intervention methods. Each assessment technique used a 4-mm action level for intervention. Outcomes were evaluated using measures of sensitivity, specificity and dosimetric effect, and compared across intervention techniques. Dosimetric effect was defined as the change in dosimetric coverage by the 95% isodose from the no intervention case of an evaluation construct called the verification target volume. Results Bony anatomy, soft tissue and dosimetric overlay-based interventions demonstrated sensitivity of 0.56, 0.73 and 1.00 and specificity of 0.64, 0.20 and 0.66, respectively. A detrimental dosimetric effect was shown in 7% of interventions for each technique, with benefit in 30%, 35% and 55% for bony anatomy, soft tissue and dosimetric overlay techniques, respectively. Conclusion Used in conjunction with soft-tissue-based corrective couch shifts, the dosimetric overlay technique allows effective filtering out of dosimetrically unnecessary interventions, making it more likely that any intervention made will result in improved target volume coverage. PMID:21385920

  4. Radiobiologically guided optimisation of the prescription dose and fractionation scheme in radiotherapy using BioSuite

    PubMed Central

    Uzan, J; Nahum, A E

    2012-01-01

    Objective Radiobiological models provide a means of evaluating treatment plans. Keeping in mind their inherent limitations, they can also be used prospectively to design new treatment strategies which maximise therapeutic ratio. We propose here a new method to customise fractionation and prescription dose. Methods To illustrate our new approach, two non-small cell lung cancer treatment plans and one prostate plan from our archive are analysed using the in-house software tool BioSuite. BioSuite computes normal tissue complication probability and tumour control probability using various radiobiological models and can suggest radiobiologically optimal prescription doses and fractionation schemes with limited toxicity. Results Dose–response curves present varied aspects depending on the nature of each case. The optimisation process suggests doses and fractionation schemes differing from the original ones. Patterns of optimisation depend on the degree of conformality, the behaviour of the normal tissue (i.e. “serial” or “parallel”), the volume of the tumour and the parameters of clonogen proliferation. Conclusion Individualising the prescription dose and number of fractions with the help of BioSuite results in improved therapeutic ratios as evaluated by radiobiological models. PMID:22457318

  5. Clinical Application of High-Dose, Image-Guided Intensity-Modulated Radiotherapy in High-Risk Prostate Cancer

    SciTech Connect

    Bayley, Andrew; Rosewall, Tara; Craig, Tim; Bristow, Rob; Chung, Peter; Gospodarowicz, Mary; Menard, Cynthia; Milosevic, Michael; Warde, Padraig; Catton, Charles

    2010-06-01

    Purpose: To report the feasibility and early toxicity of dose-escalated image-guided IMRT to the pelvic lymph nodes (LN), prostate (P), and seminal vesicles (SV). Methods and Materials: A total of 103 high-risk prostate cancer patients received two-phase, dose-escalated, image-guided IMRT with 3 years of androgen deprivation therapy. Clinical target volumes (CTVs) were delineated using computed tomography/magnetic resonance co-registration and included the prostate, portions of the SV, and the LN. Planning target volume margins (PTV) used were as follows: P (10 mm, 7 mm posteriorly), SV (10 mm), and LN (5 mm). Organs at risk (OaR) were the rectal and bladder walls, femoral heads, and large and small bowel. The IMRT was planned with an intended dose of 55.1 Gy in 29 fractions to all CTVs (Phase 1), with P+SV consecutive boost of 24.7 Gy in 13 fractions. Daily online image guidance was performed using bony landmarks and intraprostatic markers. Feasibility criteria included delivery of intended doses in 80% of patients, 95% of CTV displacements incorporated within PTV during Phase 1, and acute toxicity rate comparable to that of lower-dose pelvic techniques. Results: A total of 91 patients (88%) received the total prescription dose. All patients received at least 72 Gy. In Phase 1, 63 patients (61%) received the intended 55.1 Gy, whereas 87% of patients received at least 50 Gy. Dose reductions were caused by small bowel and rectal wall constraints. All CTVs received the planned dose in >95% of treatment fractions. There were no Radiation Therapy Oncology Group acute toxicities greater than Grade 3, although there were five incidences equivalent to Grade 3 within a median follow-up of 23 months. Conclusion: These results suggest that dose escalation to the PLN+P+SV using IMRT is feasible, with acceptable rates of acute toxicity.

  6. Do We Need Daily Image-Guided Radiotherapy by Megavoltage Computed Tomography in Head and Neck Helical Tomotherapy? The Actual Delivered Dose to the Spinal Cord

    SciTech Connect

    Duma, Marciana Nona; Kampfer, Severin; Schuster, Tibor; Aswathanarayana, Nandana; Fromm, Laura-Sophie; Molls, Michael; Andratschke, Nicolaus; Geinitz, Hans

    2012-09-01

    Purpose: To quantify the actual delivered dose to the cervical spinal cord with different image-guided radiotherapy (IGRT) approaches during head and neck (HN) cancer helical tomotherapy. Methods and Materials: Twenty HN patients (HNpts) treated with bilateral nodal irradiation were analyzed. Daily megavoltage computed tomography MVCT) scans were performed for setup purposes. The maximum dose on the planning CT scan (plan-Dmax) and the magnitude and localization of the actual delivered Dmax (a-Dmax) were analyzed for four scenarios: daily image-guided radiotherapy (dIGRT), twice weekly IGRT (2 Multiplication-Sign WkIGRT), once weekly IGRT (1 Multiplication-Sign WkIGRT), and no IGRT at all (non-IGRT). The spinal cord was recontoured on 236 MVCTs for each scenario (total, 944 fractions), and the delivered dose was recalculated for each fraction (fx) separately. Results: Fifty-one percent of the analyzed fx for dIGRT, 56% of the analyzed fx for the 2 Multiplication-Sign WkIGRT, 62% of the analyzed fx for the 1 Multiplication-Sign WkIGRT, and 63% of the analyzed fx for the non-IGRT scenarios received a higher a-Dmax than the plan-Dmax. The median increase of dose in these fx was 3.3% more for dIGRT, 5.8% more for 2 Multiplication-Sign WkIGRT, 10.0% more for 1 Multiplication-Sign WkIGRT, and 9.5% more for non-IGRT than the plan-Dmax. The median spinal cord volumes receiving a higher dose than the plan-Dmax were 0.02 cm{sup 3} for dIGRT, 0.11 cm{sup 3} for 2 Multiplication-Sign WkIGRT, 0.31 cm{sup 3} for 1 Multiplication-Sign WkIGRT, and 0.22 cm{sup 3} for non-IGRT. Differences between the dIGRT and all other scenarios were statistically significant (p < 0.05). Conclusions: Compared to the Dmax of the initial plan, daily IGRT had the smallest increase in dose. Furthermore, daily IGRT had the lowest proportion of fractions and the smallest volumes affected by a dose that was higher than the planned dose. For patients treated with doses close to the tolerance dose of the

  7. Improved Clinical Outcomes With High-Dose Image Guided Radiotherapy Compared With Non-IGRT for the Treatment of Clinically Localized Prostate Cancer

    SciTech Connect

    Zelefsky, Michael J.; Kollmeier, Marisa; Cox, Brett; Fidaleo, Anthony; Sperling, Dahlia; Pei, Xin; Carver, Brett; Coleman, Jonathan; Lovelock, Michael; Hunt, Margie

    2012-09-01

    Purpose: To compare toxicity profiles and biochemical tumor control outcomes between patients treated with high-dose image-guided radiotherapy (IGRT) and high-dose intensity-modulated radiotherapy (IMRT) for clinically localized prostate cancer. Materials and Methods: Between 2008 and 2009, 186 patients with prostate cancer were treated with IGRT to a dose of 86.4 Gy with daily correction of the target position based on kilovoltage imaging of implanted prostatic fiducial markers. This group of patients was retrospectively compared with a similar cohort of 190 patients who were treated between 2006 and 2007 with IMRT to the same prescription dose without, however, implanted fiducial markers in place (non-IGRT). The median follow-up time was 2.8 years (range, 2-6 years). Results: A significant reduction in late urinary toxicity was observed for IGRT patients compared with the non-IGRT patients. The 3-year likelihood of grade 2 and higher urinary toxicity for the IGRT and non-IGRT cohorts were 10.4% and 20.0%, respectively (p = 0.02). Multivariate analysis identifying predictors for grade 2 or higher late urinary toxicity demonstrated that, in addition to the baseline Internatinoal Prostate Symptom Score, IGRT was associated with significantly less late urinary toxicity compared with non-IGRT. The incidence of grade 2 and higher rectal toxicity was low for both treatment groups (1.0% and 1.6%, respectively; p = 0.81). No differences in prostate-specific antigen relapse-free survival outcomes were observed for low- and intermediate-risk patients when treated with IGRT and non-IGRT. For high-risk patients, a significant improvement was observed at 3 years for patients treated with IGRT compared with non-IGRT. Conclusions: IGRT is associated with an improvement in biochemical tumor control among high-risk patients and a lower rate of late urinary toxicity compared with high-dose IMRT. These data suggest that, for definitive radiotherapy, the placement of fiducial markers

  8. A Study on Target Positioning Error and Its Impact on Dose Variation in Image-Guided Stereotactic Body Radiotherapy for the Spine

    SciTech Connect

    Kim, Siyong Jin, Hosang; Yang, Huey; Amdur, Robert J.

    2009-04-01

    Purpose: To investigate the amount of target positioning error and evaluate its dosimetric impact during image-guided stereotactic body radiotherapy for single-fraction spine treatment. Methods and Materials: A prescription dose of 15 Gy and five to nine coplanar intensity-modulated beams were used. The patient was immobilized with a custom-fit vacuum mold, and the target was localized with a volumetric cone-beam CT image. A robotic couch with six degrees of freedom was used for target adjustment. For evaluation a cone-beam CT image was obtained at the end of treatment. Both target positioning error and its dosimetric impact were investigated for the first 9 cases. Results: For cases studied, translational errors were 0.9 {+-} 0.5 mm (lateral), 1.2 {+-} 0.9 mm (longitudinal), 0.7 {+-} 0.6 mm (vertical), and 1.8 {+-} 1.0 mm (vector), and rotational errors were 1.6 deg. {+-} 1.3 deg. (pitch), 0.8 deg. {+-} 0.9 deg. (roll), and 0.8 deg. {+-} 0.4{sup o} (yaw). For the clinical target volume, D{sub 95} (dose to 95% of target volume), D{sub 90}, D{sub max}, and D{sub mean} were evaluated. Only 1 case showed significant dose variations, reaching up to 18% in D{sub 95}. The spinal cord dose was evaluated by observing D{sub 0.1} (dose to 0.1 cm{sup 3}), D{sub 0.5}, D{sub 1.0}, and D{sub max}. Although 1 case showed a dose change reaching up to 30% in D{sub max}, cord dose was within the planning tolerance limit in all but 2 cases (3% higher in one and 0.4% higher in the other). Conclusion: The implemented image-guided stereotactic body radiotherapy provides precise target localization. However, despite reasonably precise spatial precision, dosimetric perturbation can be significant because of both extremely steep dose gradients and close distances between the target and the spinal cord.

  9. Long-term outcomes from dose-escalated image-guided intensity-modulated radiotherapy with androgen deprivation: encouraging results for intermediate- and high-risk prostate cancer

    PubMed Central

    Wilcox, Shea W; Aherne, Noel J; Benjamin, Linus C; Wu, Bosco; de Campos Silva, Thomaz; McLachlan, Craig S; McKay, Michael J; Last, Andrew J; Shakespeare, Thomas P

    2014-01-01

    Purpose Dose-escalated (DE) radiotherapy in the setting of localized prostate cancer has been shown to improve biochemical disease-free survival (bDFS) in several studies. In the same group of patients, androgen deprivation therapy (ADT) has been shown to confer a survival benefit when combined with radiotherapy doses of up to 70 Gy; however, there is currently little long-term data on patients who have received high-dose intensity-modulated radiotherapy (IMRT) with ADT. We report the long-term outcomes in a large cohort of patients treated with the combination of DE image-guided IMRT (IG-IMRT) and ADT. Methods and materials Patients with localized prostate cancer were identified from a centralized database across an integrated cancer center. All patients received DE IG-IMRT, combined with ADT, and had a minimum follow up of 12 months post-radiotherapy. All relapse and toxicity data were collected prospectively. Actuarial bDFS, metastasis-free survival, prostate cancer-specific survival, and multivariate analyses were calculated using the SPSS v20.0 statistical package. Results Seven hundred and eighty-two eligible patients were identified with a median follow up of 46 months. Overall, 4.3% of patients relapsed, 2.0% developed distant metastases, and 0.6% died from metastatic prostate cancer. At 5-years, bDFS was 88%, metastasis-free survival was 95%, and prostate cancer-specific survival was 98%. Five-year grade 2 genitourinary and gastrointestinal toxicity was 2.1% and 3.4%, respectively. No grade 3 or 4 late toxicities were reported. Pretreatment prostate specific antigen (P=0.001) and Gleason score (P=0.03) were significant in predicting biochemical failure on multivariate analysis. Conclusion There is a high probability of tumor control with DE IG-IMRT combined with androgen deprivation, and this is a technique with a low probability of significant late toxicity. Our long term results corroborate the safety and efficacy of treating with IG-IMRT to high doses

  10. Image-guided intensity-modulated radiotherapy for prostate cancer: Dose constraints for the anterior rectal wall to minimize rectal toxicity

    SciTech Connect

    Peterson, Jennifer L.; Buskirk, Steven J.; Heckman, Michael G.; Diehl, Nancy N.; Bernard, Johnny R.; Tzou, Katherine S.; Casale, Henry E.; Bellefontaine, Louis P.; Serago, Christopher; Kim, Siyong; Vallow, Laura A.; Daugherty, Larry C.; Ko, Stephen J.

    2014-04-01

    Rectal adverse events (AEs) are a major concern with definitive radiotherapy (RT) treatment for prostate cancer. The anterior rectal wall is at the greatest risk of injury as it lies closest to the target volume and receives the highest dose of RT. This study evaluated the absolute volume of anterior rectal wall receiving a high dose to identify potential ideal dose constraints that can minimize rectal AEs. A total of 111 consecutive patients with Stage T1c to T3a N0 M0 prostate cancer who underwent image-guided intensity-modulated RT at our institution were included. AEs were graded according to the Common Terminology Criteria for Adverse Events, version 4.0. The volume of anterior rectal wall receiving 5 to 80 Gy in 2.5-Gy increments was determined. Multivariable Cox regression models were used to identify cut points in these volumes that led to an increased risk of early and late rectal AEs. Early AEs occurred in most patients (88%); however, relatively few of them (13%) were grade ≥2. At 5 years, the cumulative incidence of late rectal AEs was 37%, with only 5% being grade ≥2. For almost all RT doses, we identified a threshold of irradiated absolute volume of anterior rectal wall above which there was at least a trend toward a significantly higher rate of AEs. Most strikingly, patients with more than 1.29, 0.73, or 0.45 cm{sup 3} of anterior rectal wall exposed to radiation doses of 67.5, 70, or 72.5 Gy, respectively, had a significantly increased risk of late AEs (relative risks [RR]: 2.18 to 2.72; p ≤ 0.041) and of grade ≥ 2 early AEs (RR: 6.36 to 6.48; p = 0.004). Our study provides evidence that definitive image-guided intensity-modulated radiotherapy (IG-IMRT) for prostate cancer is well tolerated and also identifies dose thresholds for the absolute volume of anterior rectal wall above which patients are at greater risk of early and late complications.

  11. Phase II dose escalation study of image-guided adaptive radiotherapy for prostate cancer: Use of dose-volume constraints to achieve rectal isotoxicity

    SciTech Connect

    Vargas, Carlos; Yan Di; Kestin, Larry L.; Krauss, Daniel; Lockman, David M.; Brabbins, Donald S.; Martinez, Alvaro A. . E-mail: amartinez@beaumont.edu

    2005-09-01

    significant difference by dose level was seen in the 2-year rate of Grade 2 or higher chronic rectal toxicity. These rates were 27%, 15%, 14%, 17%, and 24% for dose levels equal to or less than 72, 73.8, 75.6, 77.4, and 79.2 Gy, respectively (p = 0.3). Grade 2 or higher chronic rectal bleeding was significantly greater for Group 2 than for Group 1, 17% vs. 8% (p = 0.035). Conclusions: High doses (79.2 Gy) were safely delivered in selected patients by our adaptive radiotherapy process. Under the rectal dose-volume histogram constraints for the dose level selection, the risk of chronic rectal toxicity is similar among patients treated to different dose levels. Therefore, rectal chronic toxicity rates reflect the dose-volume cutoff used and are independent of the actual dose levels. On the other hand, a larger PTV will increase the rectal wall dose and chronic rectal toxicity rates. PTV volume and dose constraints should be defined, considering their potential benefit.

  12. Integral dose conservation in radiotherapy.

    PubMed

    Reese, Adam S; Das, Shiva K; Curie, Charles; Marks, Lawrence B

    2009-03-01

    Treatment planners frequently modify beam arrangements and use IMRT to improve target dose coverage while satisfying dose constraints on normal tissues. The authors herein analyze the limitations of these strategies and quantitatively assess the extent to which dose can be redistributed within the patient volume. Specifically, the authors hypothesize that (1) the normalized integral dose is constant across concentric shells of normal tissue surrounding the target (normalized to the average integral shell dose), (2) the normalized integral shell dose is constant across plans with different numbers and orientations of beams, and (3) the normalized integral shell dose is constant across plans when reducing the dose to a critical structure. Using the images of seven patients previously irradiated for cancer of brain or prostate cancer and one idealized scenario, competing three-dimensional conformal and IMRT plans were generated using different beam configurations. Within a given plan and for competing plans with a constant mean target dose, the normalized integral doses within concentric "shells" of surrounding normal tissue were quantitatively compared. Within each patient, the normalized integral dose to shells of normal tissue surrounding the target was relatively constant (1). Similarly, for each clinical scenario, the normalized integral dose for a given shell was also relatively constant regardless of the number and orientation of beams (2) or degree of sparing of a critical structure (3). 3D and IMRT planning tools can redistribute, rather than eliminate dose to the surrounding normal tissues (intuitively known by planners). More specifically, dose cannot be moved between shells surrounding the target but only within a shell. This implies that there are limitations in the extent to which a critical structure can be spared based on the location and geometry of the critical structure relative to the target. PMID:19378734

  13. Gold Nanoparticle Hyperthermia Reduces Radiotherapy Dose

    PubMed Central

    Lin, Lynn; Slatkin, Daniel N.; Dilmanian, F. Avraham; Vadas, Timothy M.; Smilowitz, Henry M.

    2014-01-01

    Gold nanoparticles can absorb near infrared light, resulting in heating and ablation of tumors. Gold nanoparticles have also been used for enhancing the dose of X-rays in tumors during radiotherapy. The combination of hyperthermia and radiotherapy is synergistic, importantly allowing a reduction in X-ray dose with improved therapeutic results. Here we intratumorally infused small 15 nm gold nanoparticles engineered to be transformed from infrared-transparent to infrared-absorptive by the tumor, which were then heated by infrared followed by X-ray treatment. Synergy was studied using a very radioresistant subcutaneous squamous cell carcinoma (SCCVII) in mice. It was found that the dose required to control 50% of the tumors, normally 55 Gy, could be reduced to <15 Gy (a factor of >3.7). Gold nanoparticles therefore provide a method to combine hyperthermia and radiotherapy to drastically reduce the X-ray radiation needed, thus sparing normal tissue, reducing the side effects, and making radiotherapy more effective. PMID:24990355

  14. Volumetric-modulated arc therapy (RapidArc) vs. conventional fixed-field intensity-modulated radiotherapy for {sup 18}F-FDG-PET-guided dose escalation in oropharyngeal cancer: A planning study

    SciTech Connect

    Teoh, May; Beveridge, Sabeena; Wood, Katie; Whitaker, Stephen; Adams, Elizabeth; Rickard, Donna; Jordan, Tom; Nisbet, Andrew; Clark, Catharine H.

    2013-04-01

    Fluorine-18-fluorodeoxyglucose-positron emission tomography ({sup 18}F-FDG-PET)–guided focal dose escalation in oropharyngeal cancer may potentially improve local control. We evaluated the feasibility of this approach using volumetric-modulated arc therapy (RapidArc) and compared these plans with fixed-field intensity-modulated radiotherapy (IMRT) focal dose escalation plans. Materials and methods: An initial study of 20 patients compared RapidArc with fixed-field IMRT using standard dose prescriptions. From this cohort, 10 were included in a dose escalation planning study. Dose escalation was applied to {sup 18}F-FDG-PET–positive regions in the primary tumor at dose levels of 5% (DL1), 10% (DL2), and 15% (DL3) above standard radical dose (65 Gy in 30 fractions). Fixed-field IMRT and double-arc RapidArc plans were generated for each dataset. Dose-volume histograms were used for plan evaluation and comparison. The Paddick conformity index (CI{sub Paddick}) and monitor units (MU) for each plan were recorded and compared. Both IMRT and RapidArc produced clinically acceptable plans and achieved planning objectives for target volumes. Dose conformity was significantly better in the RapidArc plans, with lower CI{sub Paddick} scores in both primary (PTV1) and elective (PTV2) planning target volumes (largest difference in PTV1 at DL3; 0.81 ± 0.03 [RapidArc] vs. 0.77 ± 0.07 [IMRT], p = 0.04). Maximum dose constraints for spinal cord and brainstem were not exceeded in both RapidArc and IMRT plans, but mean doses were higher with RapidArc (by 2.7 ± 1 Gy for spinal cord and 1.9 ± 1 Gy for brainstem). Contralateral parotid mean dose was lower with RapidArc, which was statistically significant at DL1 (29.0 vs. 29.9 Gy, p = 0.01) and DL2 (29.3 vs. 30.3 Gy, p = 0.03). MU were reduced by 39.8–49.2% with RapidArc (largest difference at DL3, 641 ± 94 vs. 1261 ± 118, p < 0.01). {sup 18}F-FDG-PET–guided focal dose escalation in oropharyngeal cancer is feasible with Rapid

  15. Low-Dose Radiotherapy in Indolent Lymphoma

    SciTech Connect

    Rossier, Christine; Schick, Ulrike; Miralbell, Raymond; Mirimanoff, Rene O.; Weber, Damien C.; Ozsahin, Mahmut

    2011-11-01

    Purpose: To assess the response rate, duration of response, and overall survival after low-dose involved-field radiotherapy in patients with recurrent low-grade lymphoma or chronic lymphocytic leukemia (CLL). Methods and Materials: Forty-three (24 women, 19 men) consecutive patients with indolent lymphoma or CLL were treated with a total dose of 4 Gy (2 x 2 Gy) using 6- 18-MV photons. The median age was 73 years (range, 39-88). Radiotherapy was given either after (n = 32; 75%) or before (n = 11; 25%) chemotherapy. The median time from diagnosis was 48 months (range, 1-249). The median follow-up period was 20 months (range, 1-56). Results: The overall response rate was 90%. Twelve patients (28%) had a complete response, 15 (35%) had a partial response, 11 (26%) had stable disease, and 5 (11%) had progressive disease. The median overall survival for patients with a positive response (complete response/partial response/stable disease) was 41 months; for patients with progressive disease it was 6 months (p = 0.001). The median time to in-field progression was 21 months (range, 0-24), and the median time to out-field progression was 8 months (range, 0-40). The 3-year in-field control was 92% in patients with complete response (median was not reached). The median time to in-field progression was 9 months (range, 0.5-24) in patients with partial response and 6 months (range, 0.6-6) in those with stable disease (p < 0.05). Younger age, positive response to radiotherapy, and no previous chemotherapy were the best factors influencing the outcome. Conclusions: Low-dose involved-field radiotherapy is an effective treatment in the management of patients with recurrent low-grade lymphoma or CLL.

  16. Online image-guided intensity-modulated radiotherapy for prostate cancer: How much improvement can we expect? A theoretical assessment of clinical benefits and potential dose escalation by improving precision and accuracy of radiation delivery

    SciTech Connect

    Ghilezan, Michel; Yan Di . E-mail: dyan@beaumont.edu; Liang Jian; Jaffray, David; Wong, John; Martinez, Alvaro

    2004-12-01

    Purpose: To quantify the theoretical benefit, in terms of improvement in precision and accuracy of treatment delivery and in dose increase, of using online image-guided intensity-modulated radiotherapy (IG-IMRT) performed with onboard cone-beam computed tomography (CT), in an ideal setting of no intrafraction motion/deformation, in the treatment of prostate cancer. Methods and materials: Twenty-two prostate cancer patients treated with conventional radiotherapy underwent multiple serial CT scans (median 18 scans per patient) during their treatment. We assumed that these data sets were equivalent to image sets obtainable by an onboard cone-beam CT. Each patient treatment was simulated with conventional IMRT and online IG-IMRT separately. The conventional IMRT plan was generated on the basis of pretreatment CT, with a clinical target volume to planning target volume (CTV-to-PTV) margin of 1 cm, and the online IG-IMRT plan was created before each treatment fraction on the basis of the CT scan of the day, without CTV-to-PTV margin. The inverse planning process was similar for both conventional IMRT and online IG-IMRT. Treatment dose for each organ of interest was quantified, including patient daily setup error and internal organ motion/deformation. We used generalized equivalent uniform dose (EUD) to compare the two approaches. The generalized EUD (percentage) of each organ of interest was scaled relative to the prescription dose at treatment isocenter for evaluation and comparison. On the basis of bladder wall and rectal wall EUD, a dose-escalation coefficient was calculated, representing the potential increment of the treatment dose achievable with online IG-IMRT as compared with conventional IMRT. Results: With respect to radiosensitive tumor, the average EUD for the target (prostate plus seminal vesicles) was 96.8% for conventional IMRT and 98.9% for online IG-IMRT, with standard deviations (SDs) of 5.6% and 0.7%, respectively (p < 0.0001). The average EUDs of

  17. High Dose-Per-Fraction Irradiation of Limited Lung Volumes Using an Image-Guided, Highly Focused Irradiator: Simulating Stereotactic Body Radiotherapy Regimens in a Small-Animal Model

    SciTech Connect

    Cho, Jaeho; Kodym, Reinhard; Seliounine, Serguei

    2010-07-01

    Purpose: To investigate the underlying biology associated with stereotactic body radiotherapy (SBRT), both in vivo models and image-guided, highly focal irradiation systems are necessary. Here, we describe such an irradiation system and use it to examine normal tissue toxicity in a small-animal model at lung volumes similar to those associated with human therapy. Methods and Materials: High-dose radiation was delivered to a small volume of the left lung of C3H/HeJCr mice using a small-animal stereotactic irradiator. The irradiator has a collimation mechanism to produce focal radiation beams, an imaging subsystem consisting of a fluorescent screen coupled to a charge-coupled device camera, and a manual positioning stage. Histopathologic examination and micro-CT were used to evaluate the radiation response. Results: Focal obliteration of the alveoli by fibrous connective tissue, hyperplasia of the bronchiolar epithelium, and presence of a small number of inflammatory cells are the main reactions to low-volume/high-dose irradiation of the mouse lung. The tissue response suggested a radiation dose threshold for early phase fibrosis lying between 40 and 100 Gy. The irradiation system satisfied our requirements of high-dose-rate, small beam diameter, and precise localization and verification. Conclusions: We have established an experimental model and image-guided animal irradiation system for the study of high dose per fraction irradiations such as those used with SBRT at volumes analogous to those used in human beings. It will also allow the targeting of specific anatomical structures of the thorax or ultimately, orthotopic tumors of the lung.

  18. Radiotherapy Dose Fractionation under Parameter Uncertainty

    NASA Astrophysics Data System (ADS)

    Davison, Matt; Kim, Daero; Keller, Harald

    2011-11-01

    In radiotherapy, radiation is directed to damage a tumor while avoiding surrounding healthy tissue. Tradeoffs ensue because dose cannot be exactly shaped to the tumor. It is particularly important to ensure that sensitive biological structures near the tumor are not damaged more than a certain amount. Biological tissue is known to have a nonlinear response to incident radiation. The linear quadratic dose response model, which requires the specification of two clinically and experimentally observed response coefficients, is commonly used to model this effect. This model yields an optimization problem giving two different types of optimal dose sequences (fractionation schedules). Which fractionation schedule is preferred depends on the response coefficients. These coefficients are uncertainly known and may differ from patient to patient. Because of this not only the expected outcomes but also the uncertainty around these outcomes are important, and it might not be prudent to select the strategy with the best expected outcome.

  19. Radiotherapy Dose Fractionation under Parameter Uncertainty

    SciTech Connect

    Davison, Matt; Kim, Daero; Keller, Harald

    2011-11-30

    In radiotherapy, radiation is directed to damage a tumor while avoiding surrounding healthy tissue. Tradeoffs ensue because dose cannot be exactly shaped to the tumor. It is particularly important to ensure that sensitive biological structures near the tumor are not damaged more than a certain amount. Biological tissue is known to have a nonlinear response to incident radiation. The linear quadratic dose response model, which requires the specification of two clinically and experimentally observed response coefficients, is commonly used to model this effect. This model yields an optimization problem giving two different types of optimal dose sequences (fractionation schedules). Which fractionation schedule is preferred depends on the response coefficients. These coefficients are uncertainly known and may differ from patient to patient. Because of this not only the expected outcomes but also the uncertainty around these outcomes are important, and it might not be prudent to select the strategy with the best expected outcome.

  20. Dose masking feature for BNCT radiotherapy planning

    DOEpatents

    Cook, Jeremy L.; Wessol, Daniel E.; Wheeler, Floyd J.

    2000-01-01

    A system for displaying an accurate model of isodoses to be used in radiotherapy so that appropriate planning can be performed prior to actual treatment on a patient. The nature of the simulation of the radiotherapy planning for BNCT and Fast Neutron Therapy, etc., requires that the doses be computed in the entire volume. The "entire volume" includes the patient and beam geometries as well as the air spaces in between. Isodoses derived from the computed doses will therefore extend into the air regions between the patient and beam geometries and thus depict the unrealistic possibility that radiation deposition occurs in regions containing no physical media. This problem is solved by computing the doses for the entire geometry and then masking the physical and air regions along with the isodose contours superimposed over the patient image at the corresponding plane. The user is thus able to mask out (remove) the contour lines from the unwanted areas of the image by selecting the appropriate contour masking region from the raster image.

  1. Dynamic targeting image-guided radiotherapy

    SciTech Connect

    Huntzinger, Calvin; Munro, Peter; Johnson, Scott; Miettinen, Mika; Zankowski, Corey; Ahlstrom, Greg; Glettig, Reto; Filliberti, Reto; Kaissl, Wolfgang; Kamber, Martin; Amstutz, Martin; Bouchet, Lionel; Klebanov, Dan; Mostafavi, Hassan; Stark, Richard

    2006-07-01

    Volumetric imaging and planning for 3-dimensional (3D) conformal radiotherapy and intensity-modulated radiotherapy (IMRT) have highlighted the need to the oncology community to better understand the geometric uncertainties inherent in the radiotherapy delivery process, including setup error (interfraction) as well as organ motion during treatment (intrafraction). This has ushered in the development of emerging technologies and clinical processes, collectively referred to as image-guided radiotherapy (IGRT). The goal of IGRT is to provide the tools needed to manage both inter- and intrafraction motion to improve the accuracy of treatment delivery. Like IMRT, IGRT is a process involving all steps in the radiotherapy treatment process, including patient immobilization, computed tomogaphy (CT) simulation, treatment planning, plan verification, patient setup verification and correction, delivery, and quality assurance. The technology and capability of the Dynamic Targeting{sup TM} IGRT system developed by Varian Medical Systems is presented. The core of this system is a Clinac (registered) or Trilogy{sup TM} accelerator equipped with a gantry-mounted imaging system known as the On-Board Imager{sup TM} (OBI). This includes a kilovoltage (kV) x-ray source, an amorphous silicon kV digital image detector, and 2 robotic arms that independently position the kV source and imager orthogonal to the treatment beam. A similar robotic arm positions the PortalVision{sup TM} megavoltage (MV) portal digital image detector, allowing both to be used in concert. The system is designed to support a variety of imaging modalities. The following applications and how they fit in the overall clinical process are described: kV and MV planar radiographic imaging for patient repositioning, kV volumetric cone beam CT imaging for patient repositioning, and kV planar fluoroscopic imaging for gating verification. Achieving image-guided motion management throughout the radiation oncology process

  2. MRI-guided prostate adaptive radiotherapy - A systematic review.

    PubMed

    McPartlin, A J; Li, X A; Kershaw, L E; Heide, U; Kerkmeijer, L; Lawton, C; Mahmood, U; Pos, F; van As, N; van Herk, M; Vesprini, D; van der Voort van Zyp, J; Tree, A; Choudhury, A

    2016-06-01

    Dose escalated radiotherapy improves outcomes for men with prostate cancer. A plateau for benefit from dose escalation using EBRT may not have been reached for some patients with higher risk disease. The use of increasingly conformal techniques, such as step and shoot IMRT or more recently VMAT, has allowed treatment intensification to be achieved whilst minimising associated increases in toxicity to surrounding normal structures. To support further safe dose escalation, the uncertainties in the treatment target position will need be minimised using optimal planning and image-guided radiotherapy (IGRT). In particular the increasing usage of profoundly hypo-fractionated stereotactic therapy is predicated on the ability to confidently direct treatment precisely to the intended target for the duration of each treatment. This article reviews published studies on the influences of varies types of motion on daily prostate position and how these may be mitigated to improve IGRT in future. In particular the role that MRI has played in the generation of data is discussed and the potential role of the MR-Linac in next-generation IGRT is discussed. PMID:27162159

  3. Rationale and development of image-guided intensity-modulated radiotherapy post-prostatectomy: the present standard of care?

    PubMed Central

    Murray, Julia R; McNair, Helen A; Dearnaley, David P

    2015-01-01

    The indications for post-prostatectomy radiotherapy have evolved over the last decade, although the optimal timing, dose, and target volume remain to be well defined. The target volume is susceptible to anatomical variations with its borders interfacing with the rectum and bladder. Image-guided intensity-modulated radiotherapy has become the gold standard for radical prostate radiotherapy. Here we review the current evidence for image-guided techniques with intensity-modulated radiotherapy to the prostate bed and describe current strategies to reduce or account for interfraction and intrafraction motion. PMID:26635484

  4. Image-Guided Radiotherapy and -Brachytherapy for Cervical Cancer

    PubMed Central

    Dutta, Suresh; Nguyen, Nam Phong; Vock, Jacqueline; Kerr, Christine; Godinez, Juan; Bose, Satya; Jang, Siyoung; Chi, Alexander; Almeida, Fabio; Woods, William; Desai, Anand; David, Rick; Karlsson, Ulf Lennart; Altdorfer, Gabor

    2015-01-01

    Conventional radiotherapy for cervical cancer relies on clinical examination, 3-dimensional conformal radiotherapy (3D-CRT), and 2-dimensional intracavitary brachytherapy. Excellent local control and survival have been obtained for small early stage cervical cancer with definitive radiotherapy. For bulky and locally advanced disease, the addition of chemotherapy has improved the prognosis but toxicity remains significant. New imaging technology such as positron-emission tomography and magnetic resonance imaging has improved tumor delineation for radiotherapy planning. Image-guided radiotherapy (IGRT) may decrease treatment toxicity of whole pelvic radiation because of its potential for bone marrow, bowel, and bladder sparring. Tumor shrinkage during whole pelvic IGRT may optimize image-guided brachytherapy (IGBT), allowing for better local control and reduced toxicity for patients with cervical cancer. IGRT and IGBT should be integrated in future prospective studies for cervical cancer. PMID:25853092

  5. Image-guided radiotherapy and -brachytherapy for cervical cancer.

    PubMed

    Dutta, Suresh; Nguyen, Nam Phong; Vock, Jacqueline; Kerr, Christine; Godinez, Juan; Bose, Satya; Jang, Siyoung; Chi, Alexander; Almeida, Fabio; Woods, William; Desai, Anand; David, Rick; Karlsson, Ulf Lennart; Altdorfer, Gabor

    2015-01-01

    Conventional radiotherapy for cervical cancer relies on clinical examination, 3-dimensional conformal radiotherapy (3D-CRT), and 2-dimensional intracavitary brachytherapy. Excellent local control and survival have been obtained for small early stage cervical cancer with definitive radiotherapy. For bulky and locally advanced disease, the addition of chemotherapy has improved the prognosis but toxicity remains significant. New imaging technology such as positron-emission tomography and magnetic resonance imaging has improved tumor delineation for radiotherapy planning. Image-guided radiotherapy (IGRT) may decrease treatment toxicity of whole pelvic radiation because of its potential for bone marrow, bowel, and bladder sparring. Tumor shrinkage during whole pelvic IGRT may optimize image-guided brachytherapy (IGBT), allowing for better local control and reduced toxicity for patients with cervical cancer. IGRT and IGBT should be integrated in future prospective studies for cervical cancer. PMID:25853092

  6. A dose comparison of proton radiotherapy and photon radiotherapy for pediatric brain tumor

    NASA Astrophysics Data System (ADS)

    Kim, S. Y.; Cho, J. H.

    2014-12-01

    The purpose of this study was to investigate the effectiveness of photon radiotherapy and to compare the dose of treatment planning between proton radiotherapy and 3D conformal radiation therapy (3D-CRT) for pediatric brain tumor patients. This study was conducted in five pediatric brain tumor patients who underwent craniospinal irradiation treatment from October 2013 to April 2014 in the hospital. The study compared organs at risk (OARs) by assessing the dose distribution of normal tissue from the proton plan and 3D-CRT. Furthermore, this study assessed the treatment plans by looking at the homogeneity index (HI) and conformity index (CI). As a result, the study revealed OARs due to the small volume proton radiotherapy dose distribution in the normal tissue. Also, by comparing HI and CI between the 3D-CRT and proton radiotherapy plan, the study found that the dose of proton radiotherapy plan was homogenized. When conducting 3D-CRT and proton radiotherapy in a dose-volume histogram comparison, the dose of distribution turned out to be low. Consequently, proton radiotherapy is used for protecting the normal tissue, and is used in tumor tissue as a homogenized dose for effective treatment.

  7. Incidence of Secondary Cancer Development After High-Dose Intensity-Modulated Radiotherapy and Image-Guided Brachytherapy for the Treatment of Localized Prostate Cancer

    SciTech Connect

    Zelefsky, Michael J.; Housman, Douglas M.; Pei Xin; Alicikus, Zumre; Magsanoc, Juan Martin; Dauer, Lawrence T.; St Germain, Jean; Yamada, Yoshiya; Kollmeier, Marisa; Cox, Brett; Zhang Zhigang

    2012-07-01

    Purpose: To report the incidence and excess risk of second malignancy (SM) development compared with the general population after external beam radiotherapy (EBRT) and brachytherapy to treat prostate cancer. Methods and Materials: Between 1998 and 2001, 1,310 patients with localized prostate cancer were treated with EBRT (n = 897) or brachytherapy (n = 413). We compared the incidence of SMs in our patients with that of the general population extracted from the National Cancer Institute's Surveillance, Epidemiology, and End Results data set combined with the 2000 census data. Results: The 10-year likelihood of SM development was 25% after EBRT and 15% after brachytherapy (p = .02). The corresponding 10-year likelihood for in-field SM development in these groups was 4.9% and 1.6% (p = .24). Multivariate analysis showed that EBRT vs. brachytherapy and older age were the only significant predictors for the development of all SMs (p = .037 and p = .030), with a trend for older patients to develop a SM. The increased incidence of SM for EBRT patients was explained by the greater incidence of skin cancer outside the radiation field compared with that after brachytherapy (10.6% and 3.3%, respectively, p = .004). For the EBRT group, the 5- and 10-year mortality rate was 1.96% and 5.1% from out-of field cancer, respectively; for in-field SM, the corresponding mortality rates were 0.1% and 0.7%. Among the brachytherapy group, the 5- and 10-year mortality rate related to out-of field SM was 0.8% and 2.7%, respectively. Our observed SM rates after prostate RT were not significantly different from the cancer incidence rates in the general population. Conclusions: Using modern sophisticated treatment techniques, we report low rates of in-field bladder and rectal SM risks after prostate cancer RT. Furthermore, the likelihood of mortality secondary to a SM was unusual. The greater rate of SM observed with EBRT vs. brachytherapy was related to a small, but significantly increased

  8. Effect of image-guided hypofractionated stereotactic radiotherapy on peripheral non-small-cell lung cancer

    PubMed Central

    Wang, Shu-wen; Ren, Juan; Yan, Yan-li; Xue, Chao-fan; Tan, Li; Ma, Xiao-wei

    2016-01-01

    The objective of this study was to compare the effects of image-guided hypofractionated radiotherapy and conventional fractionated radiotherapy on non-small-cell lung cancer (NSCLC). Fifty stage- and age-matched cases with NSCLC were randomly divided into two groups (A and B). There were 23 cases in group A and 27 cases in group B. Image-guided radiotherapy (IGRT) and stereotactic radiotherapy were conjugately applied to the patients in group A. Group A patients underwent hypofractionated radiotherapy (6–8 Gy/time) three times per week, with a total dose of 64–66 Gy; group B received conventional fractionated radiotherapy, with a total dose of 68–70 Gy five times per week. In group A, 1-year and 2-year local failure survival rate and 1-year local failure-free survival rate were significantly higher than in group B (P<0.05). The local failure rate (P<0.05) and distant metastasis rate (P>0.05) were lower in group A than in group B. The overall survival rate of group A was significantly higher than that of group B (P=0.03), and the survival rate at 1 year was 87% vs 63%, (P<0.05). The median survival time of group A was longer than that of group B. There was no significant difference in the incidence of complications between the two groups (P>0.05). Compared with conventional fractionated radiation therapy, image-guided hypofractionated stereotactic radiotherapy in NSCLC received better treatment efficacy and showed good tolerability. PMID:27574441

  9. Clinical Experience With Image-Guided Radiotherapy in an Accelerated Partial Breast Intensity-Modulated Radiotherapy Protocol

    SciTech Connect

    Leonard, Charles E.; Tallhamer, Michael M.S.; Johnson, Tim; Hunter, Kari C.M.D.; Howell, Kathryn; Kercher, Jane; Widener, Jodi; Kaske, Terese; Paul, Devchand; Sedlacek, Scot; Carter, Dennis L.

    2010-02-01

    Purpose: To explore the feasibility of fiducial markers for the use of image-guided radiotherapy (IGRT) in an accelerated partial breast intensity modulated radiotherapy protocol. Methods and Materials: Nineteen patients consented to an institutional review board approved protocol of accelerated partial breast intensity-modulated radiotherapy with fiducial marker placement and treatment with IGRT. Patients (1 patient with bilateral breast cancer; 20 total breasts) underwent ultrasound guided implantation of three 1.2- x 3-mm gold markers placed around the surgical cavity. For each patient, table shifts (inferior/superior, right/left lateral, and anterior/posterior) and minimum, maximum, mean error with standard deviation were recorded for each of the 10 BID treatments. The dose contribution of daily orthogonal films was also examined. Results: All IGRT patients underwent successful marker placement. In all, 200 IGRT treatment sessions were performed. The average vector displacement was 4 mm (range, 2-7 mm). The average superior/inferior shift was 2 mm (range, 0-5 mm), the average lateral shift was 2 mm (range, 1-4 mm), and the average anterior/posterior shift was 3 mm (range, 1 5 mm). Conclusions: This study shows that the use of IGRT can be successfully used in an accelerated partial breast intensity-modulated radiotherapy protocol. The authors believe that this technique has increased daily treatment accuracy and permitted reduction in the margin added to the clinical target volume to form the planning target volume.

  10. Low-dose prophylactic craniospinal radiotherapy for intracranial germinoma

    SciTech Connect

    Schoenfeld, Gordon O.; Amdur, Robert J. . E-mail: amdurrj@ufl.edu; Schmalfuss, Ilona M.; Morris, Christopher G.; Keole, Sameer R.; Mendenhall, William M.; Marcus, Robert B.

    2006-06-01

    Purpose: To report outcomes of patients with localized intracranial germinoma treated with low-dose craniospinal irradiation (CSI) followed by a boost to the ventricular system and primary site. Methods and Materials: Thirty-one patients had pathologically confirmed intracranial germinoma and no spine metastases. Low-dose CSI was administered in 29 patients: usually 21 Gy of CSI, 9.0 Gy of ventricular boost, and a 19.5-Gy tumor boost, all at 1.5 Gy per fraction. Our neuroradiologist recorded three-dimensional tumor size on magnetic resonance images before, during, and after radiotherapy. Results: With a median follow-up of 7.0 years, 29 of 31 patients (94%) are disease free. One failure had nongerminomatous histology; the initial diagnosis was a sampling error. Of 3 patients who did not receive CSI, 1 died. No patient developed myelopathy, visual deficits, dementia, or skeletal growth problems. In locally controlled patients, tumor response according to magnetic resonance scan was nearly complete within 6 months after radiotherapy. Conclusions: Radiotherapy alone with low-dose prophylactic CSI cures almost all patients with localized intracranial germinoma. Complications are rare when the daily dose of radiotherapy is limited to 1.5 Gy and the total CSI dose to 21 Gy. Patients without a near-complete response to radiotherapy should undergo resection to rule out a nongerminomatous element.

  11. Organ doses can be estimated from the computed tomography (CT) dose index for cone-beam CT on radiotherapy equipment.

    PubMed

    Martin, Colin J; Abuhaimed, Abdullah; Sankaralingam, Marimuthu; Metwaly, Mohamed; Gentle, David J

    2016-06-01

    Cone beam computed tomography (CBCT) systems are fitted to radiotherapy linear accelerators and used for patient positioning prior to treatment by image guided radiotherapy (IGRT). Radiotherapists' and radiographers' knowledge of doses to organs from CBCT imaging is limited. The weighted CT dose index for a reference beam of width 20 mm (CTDIw,ref) is displayed on Varian CBCT imaging equipment known as an On-Board Imager (OBI) linked to the Truebeam linear accelerator. This has the potential to provide an indication of organ doses. This knowledge would be helpful for guidance of radiotherapy clinicians preparing treatments. Monte Carlo simulations of imaging protocols for head, thorax and pelvic scans have been performed using EGSnrc/BEAMnrc, EGSnrc/DOSXYZnrc, and ICRP reference computational male and female phantoms to derive the mean absorbed doses to organs and tissues, which have been compared with values for the CTDIw,ref displayed on the CBCT scanner console. Substantial variations in dose were observed between male and female phantoms. Nevertheless, the CTDIw,ref gave doses within  ±21% for the stomach and liver in thorax scans and 2  ×  CTDIw,ref can be used as a measure of doses to breast, lung and oesophagus. The CTDIw,ref could provide indications of doses to the brain for head scans, and the colon for pelvic scans. It is proposed that knowledge of the link between CTDIw for CBCT should be promoted and included in the training of radiotherapy staff. PMID:26975735

  12. Clinical Results of a Pilot Study on Stereovision-Guided Stereotactic Radiotherapy and Intensity Modulated Radiotherapy

    PubMed Central

    Li, Shidong; Kleinberg, Lawrence R.; Rigamonti, Daniele; Wharam, Moody D.; Rashid, Abdul; Jackson, Juan; Djajaputra, David; He, Shenjen; Creasey, Tunisia; DeWeese, Theodore L.

    2011-01-01

    Real-time stereovision-guidance has been introduced for efficient and convenient fractionated stereotactic radiotherapy (FSR) and image-guided intensity-modulated radiation therapy (IMRT). This first pilot study is to clinically evaluate its accuracy and precision as well as impact on treatment doses. Sixty-one FSR patients wearing stereotactic masks (SMs) and nine IMRT patients wearing flexible masks (FMs), were accrued. Daily target reposition was initially based-on biplane-radiographs and then adjusted in six degrees of freedom under real-time stereovision guidance. Mean and standard deviation of the head displacements measured the accuracy and precision. Head positions during beam-on times were measured with real-time stereovisions and used for determination of delivered doses. Accuracy ± precision in direction with the largest errors shows improvement from 0.4 ± 2.3 mm to 0.0 ± 1.0 mm in the inferior-to-superior direction for patients wearing SM or from 0.8 ± 4.3 mm to 0.4 ± 1.7 mm in the posterior-to-anterior direction for patients wearing FM. The image-guidance increases target volume coverage by >30% for small lesions. Over half of head position errors could be removed from the stereovision-guidance. Importantly, the technique allows us to check head position during beam-on time and makes it possible for having frameless head refixation without tight masks. PMID:21070083

  13. Radiotherapy Dose-Volume Effects on Salivary Gland Function

    SciTech Connect

    Deasy, Joseph O.; Moiseenko, Vitali; Marks, Lawrence; Chao, K.S. Clifford; Nam, Jiho; Eisbruch, Avraham

    2010-03-01

    Publications relating parotid dose-volume characteristics to radiotherapy-induced salivary toxicity were reviewed. Late salivary dysfunction has been correlated to the mean parotid gland dose, with recovery occurring with time. Severe xerostomia (defined as long-term salivary function of <25% of baseline) is usually avoided if at least one parotid gland is spared to a mean dose of less than {approx}20 Gy or if both glands are spared to less than {approx}25 Gy (mean dose). For complex, partial-volume RT patterns (e.g., intensity-modulated radiotherapy), each parotid mean dose should be kept as low as possible, consistent with the desired clinical target volume coverage. A lower parotid mean dose usually results in better function. Submandibular gland sparing also significantly decreases the risk of xerostomia. The currently available predictive models are imprecise, and additional study is required to identify more accurate models of xerostomia risk.

  14. Radiotherapy Dose-Volume Effects on Salivary Gland Function

    PubMed Central

    Deasy, Joseph O.; Moiseenko, Vitali; Marks, Lawrence; Chao, K. S. Clifford; Nam, Jiho; Eilsbruch, Avraham

    2013-01-01

    Publications relating parotid dose-volume characteristics to radiotherapy-induced salivary toxicity were reviewed. Late salivary dysfunction has been correlated to the mean parotid gland dose, with recovery occurring with time. Severe xerostomia (defined as long-term salivary function of <25% of baseline) is usually avoided if at least one parotid gland is spared to a mean dose of less than ≈20 Gy or if both glands are spared to less than ≈25 Gy (mean dose). For complex, partial-volume RT patterns (e.g., intensity-modulated radiotherapy), each parotid mean dose should be kept as low as possible, consistent with the desired clinical target volume coverage. A lower parotid mean dose usually results in better function. Submandibular gland sparing also significantly decreases the risk of xerostomia. The currently available predictive models are imprecise, and additional study is required to identify more accurate models of xerostomia risk. PMID:20171519

  15. Monte Carlo modeling of ultrasound probes for image guided radiotherapy

    SciTech Connect

    Bazalova-Carter, Magdalena; Schlosser, Jeffrey; Chen, Josephine; Hristov, Dimitre

    2015-10-15

    X6-1 probe in vertical orientation caused the highest attenuation of the 6 and 15 MV beams, which at 10 cm depth accounted for 33% and 43% decrease compared to the respective (15 × 15) cm{sup 2} open fields. The C5-2 probe in horizontal orientation, on the other hand, caused a dose increase of 10% and 53% for the 6 and 15 MV beams, respectively, in the buildup region at 0.5 cm depth. For the X6-1 probe in vertical orientation, the dose at 5 cm depth for the 3-cm diameter 6 MV and 5-cm diameter 15 MV beams was attenuated compared to the corresponding open fields to a greater degree by 65% and 43%, respectively. Conclusions: MC models of two US probes used for real-time image guidance during radiotherapy have been built. Due to the high beam attenuation of the US probes, the authors generally recommend avoiding delivery of treatment beams that intersect the probe. However, the presented MC models can be effectively integrated into US-guided radiotherapy treatment planning in cases for which beam avoidance is not practical due to anatomy geometry.

  16. In vivo skin dose measurement in breast conformal radiotherapy

    PubMed Central

    Soleymanifard, Shokouhozaman; Noghreiyan, Atefeh Vejdani; Ghorbani, Mahdi; Jamali, Farideh; Davenport, David

    2016-01-01

    Aim of the study Accurate skin dose assessment is necessary during breast radiotherapy to assure that the skin dose is below the tolerance level and is sufficient to prevent tumour recurrence. The aim of the current study is to measure the skin dose and to evaluate the geometrical/anatomical parameters that affect it. Material and methods Forty patients were simulated by TIGRT treatment planning system and treated with two tangential fields of 6 MV photon beam. Wedge filters were used to homogenise dose distribution for 11 patients. Skin dose was measured by thermoluminescent dosimeters (TLD-100) and the effects of beam incident angle, thickness of irradiated region, and beam entry separation on the skin dose were analysed. Results Average skin dose in treatment course of 50 Gy to the clinical target volume (CTV) was 36.65 Gy. The corresponding dose values for patients who were treated with and without wedge filter were 35.65 and 37.20 Gy, respectively. It was determined that the beam angle affected the average skin dose while the thickness of the irradiated region and the beam entry separation did not affect dose. Since the skin dose measured in this study was lower than the amount required to prevent tumour recurrence, application of bolus material in part of the treatment course is suggested for post-mastectomy advanced breast radiotherapy. It is more important when wedge filters are applied to homogenize dose distribution. PMID:27358592

  17. Actual Dose Variation of Parotid Glands and Spinal Cord for Nasopharyngeal Cancer Patients During Radiotherapy

    SciTech Connect

    Han Chunhui Chen Yijen; Liu An; Schultheiss, Timothy E.; Wong, Jeffrey Y.C.

    2008-03-15

    Purpose: For intensity-modulated radiotherapy of nasopharyngeal cancer, accurate dose delivery is crucial to the success of treatment. This study aimed to evaluate the significance of daily image-guided patient setup corrections and to quantify the parotid gland volume and dose variations for nasopharyngeal cancer patients using helical tomotherapy megavoltage computed tomography (CT). Methods and Materials: Five nasopharyngeal cancer patients who underwent helical tomotherapy were selected retrospectively. Each patient had received 70 Gy in 35 fractions. Daily megavoltage CT scans were registered with the planning CT images to correct the patient setup errors. Contours of the spinal cord and parotid glands were drawn on the megavoltage CT images at fixed treatment intervals. The actual doses delivered to the critical structures were calculated using the helical tomotherapy Planned Adaptive application. Results: The maximal dose to the spinal cord showed a significant increase and greater variation without daily setup corrections. The significant decrease in the parotid gland volume led to a greater median dose in the later phase of treatment. The average parotid gland volume had decreased from 20.5 to 13.2 cm{sup 3} by the end of treatment. On average, the median dose to the parotid glands was 83 cGy and 145 cGy for the first and the last treatment fractions, respectively. Conclusions: Daily image-guided setup corrections can eliminate significant dose variations to critical structures. Constant monitoring of patient anatomic changes and selective replanning should be used during radiotherapy to avoid critical structure complications.

  18. [Image-guided radiotherapy and partial delegation to radiotherapy technicians: Clermont-Ferrand experience].

    PubMed

    Loos, G; Moreau, J; Miroir, J; Benhaïm, C; Biau, J; Caillé, C; Bellière, A; Lapeyre, M

    2013-10-01

    The various image-guided radiotherapy techniques raise the question of how to achieve the control of patient positioning before irradiation session and sharing of tasks between radiation oncologists and radiotherapy technicians. We have put in place procedures and operating methods to make a partial delegation of tasks to radiotherapy technicians and secure the process in three situations: control by orthogonal kV imaging (kV-kV) of bony landmarks, control by kV-kV imaging of intraprostatic fiducial goldmarkers and control by cone beam CT (CBCT) imaging for prostate cancer. Significant medical overtime is required to control these three IGRT techniques. Because of their competence in imaging, these daily controls can be delegated to radiotherapy technicians. However, to secure the process, initial training and regular evaluation are essential. The analysis of the comparison of the use of kV/kV on bone structures allowed us to achieve a partial delegation of control to radiotherapy technicians. Controlling the positioning of the prostate through the use and automatic registration of fiducial goldmarkers allows better tracking of the prostate and can be easily delegated to radiotherapy technicians. The analysis of the use of daily cone beam CT for patients treated with intensity modulated irradiation is underway, and a comparison of practices between radiotherapy technicians and radiation oncologists is ongoing to know if a partial delegation of this control is possible. PMID:24011600

  19. Challenges of Using High-Dose Fractionation Radiotherapy in Combination Therapy

    PubMed Central

    Yang, Ying-Chieh; Chiang, Chi-Shiun

    2016-01-01

    Radiotherapy is crucial and substantially contributes to multimodal cancer treatment. The combination of conventional fractionation radiotherapy (CFRT) and systemic therapy has been established as the standard treatment for many cancer types. With advances in linear accelerators and image-guided techniques, high-dose fractionation radiotherapy (HFRT) is increasingly introduced in cancer centers. Clinicians are currently integrating HFRT into multimodality treatment. The shift from CFRT to HFRT reveals different effects on the tumor microenvironment and responses, particularly the immune response. Furthermore, the combination of HFRT and drugs yields different results in different types of tumors or using different treatment schemes. We have reviewed clinical trials and preclinical evidence on the combination of HFRT with drugs, such as chemotherapy, targeted therapy, and immune therapy. Notably, HFRT apparently enhances tumor cell killing and antigen presentation, thus providing opportunities and challenges in treating cancer. PMID:27446811

  20. Dose factor entry and display tool for BNCT radiotherapy

    DOEpatents

    Wessol, Daniel E.; Wheeler, Floyd J.; Cook, Jeremy L.

    1999-01-01

    A system for use in Boron Neutron Capture Therapy (BNCT) radiotherapy planning where a biological distribution is calculated using a combination of conversion factors and a previously calculated physical distribution. Conversion factors are presented in a graphical spreadsheet so that a planner can easily view and modify the conversion factors. For radiotherapy in multi-component modalities, such as Fast-Neutron and BNCT, it is necessary to combine each conversion factor component to form an effective dose which is used in radiotherapy planning and evaluation. The Dose Factor Entry and Display System is designed to facilitate planner entry of appropriate conversion factors in a straightforward manner for each component. The effective isodose is then immediately computed and displayed over the appropriate background (e.g. digitized image).

  1. Implementation of an analytical model for leakage neutron equivalent dose in a proton radiotherapy planning system.

    PubMed

    Eley, John; Newhauser, Wayne; Homann, Kenneth; Howell, Rebecca; Schneider, Christopher; Durante, Marco; Bert, Christoph

    2015-01-01

    Equivalent dose from neutrons produced during proton radiotherapy increases the predicted risk of radiogenic late effects. However, out-of-field neutron dose is not taken into account by commercial proton radiotherapy treatment planning systems. The purpose of this study was to demonstrate the feasibility of implementing an analytical model to calculate leakage neutron equivalent dose in a treatment planning system. Passive scattering proton treatment plans were created for a water phantom and for a patient. For both the phantom and patient, the neutron equivalent doses were small but non-negligible and extended far beyond the therapeutic field. The time required for neutron equivalent dose calculation was 1.6 times longer than that required for proton dose calculation, with a total calculation time of less than 1 h on one processor for both treatment plans. Our results demonstrate that it is feasible to predict neutron equivalent dose distributions using an analytical dose algorithm for individual patients with irregular surfaces and internal tissue heterogeneities. Eventually, personalized estimates of neutron equivalent dose to organs far from the treatment field may guide clinicians to create treatment plans that reduce the risk of late effects. PMID:25768061

  2. Implementation of an Analytical Model for Leakage Neutron Equivalent Dose in a Proton Radiotherapy Planning System

    PubMed Central

    Eley, John; Newhauser, Wayne; Homann, Kenneth; Howell, Rebecca; Schneider, Christopher; Durante, Marco; Bert, Christoph

    2015-01-01

    Equivalent dose from neutrons produced during proton radiotherapy increases the predicted risk of radiogenic late effects. However, out-of-field neutron dose is not taken into account by commercial proton radiotherapy treatment planning systems. The purpose of this study was to demonstrate the feasibility of implementing an analytical model to calculate leakage neutron equivalent dose in a treatment planning system. Passive scattering proton treatment plans were created for a water phantom and for a patient. For both the phantom and patient, the neutron equivalent doses were small but non-negligible and extended far beyond the therapeutic field. The time required for neutron equivalent dose calculation was 1.6 times longer than that required for proton dose calculation, with a total calculation time of less than 1 h on one processor for both treatment plans. Our results demonstrate that it is feasible to predict neutron equivalent dose distributions using an analytical dose algorithm for individual patients with irregular surfaces and internal tissue heterogeneities. Eventually, personalized estimates of neutron equivalent dose to organs far from the treatment field may guide clinicians to create treatment plans that reduce the risk of late effects. PMID:25768061

  3. Data required for testicular dose calculation during radiotherapy of seminoma

    SciTech Connect

    Mazonakis, Michalis; Kokona, Georgiana; Varveris, Haralambos; Damilakis, John; Gourtsoyiannis, Nicholas

    2006-07-15

    The purpose of this study was to provide the required data for the direct calculation of testicular dose resulting from radiotherapy in patients with seminoma. Paraortic (PA) treatment fields and dog-leg (DL) portals including paraortic and ipsilateral pelvic nodes were simulated on a male anthropomorphic phantom equipped with an artificial testicle. Anterior and posterior irradiations were performed for five different PA and DL field dimensions. Dose measurements were carried out using a calibrated ionization chamber. The dependence of testicular dose upon the distance separating the testicle from the treatment volume and upon the tissue thickness at the entrance point of the beam was investigated. A clamshell lead shield was used to reduce testicular dose. The scattered dose to testicle was measured in nine patients using thermoluminescent dosimeters. Phantom and patient exposures were generated with a 6 MV x-ray beam. Linear and nonlinear regression analysis was employed to obtain formulas describing the relation between the radiation dose to an unshielded and/or shielded testicle with the field size and the distance from the inferior field edge. Correction factors showing the variation of testicular dose with the patient thickness along beam axis were found. Bland-Altman statistical analysis showed that testicular dose obtained by the proposed calculation method may differ from the measured dose value by less than 25%. The current study presents a method providing reasonable estimations of testicular dose for individual patients undergoing PA or DL radiotherapy.

  4. Image-guided high-dose-rate brachytherapy in inoperable endometrial cancer

    PubMed Central

    Petsuksiri, J; Chansilpa, Y; Hoskin, P J

    2014-01-01

    Inoperable endometrial cancer may be treated with curative aim using radical radiotherapy alone. The radiation techniques are external beam radiotherapy (EBRT) alone, EBRT plus brachytherapy and brachytherapy alone. Recently, high-dose-rate brachytherapy has been used instead of low-dose-rate brachytherapy. Image-guided brachytherapy enables sufficient coverage of tumour and reduction of dose to the organs at risk, thus increasing the therapeutic ratio of treatment. Local control rates with three-dimensional brachytherapy appear better than with conventional techniques (about 90–100% and 70–90%, respectively). PMID:24807067

  5. Optimum dose of radiotherapy for chemodectomas of the middle ear

    SciTech Connect

    Kim, J.A.; Elkon, D.; Lim, M.L.; Constable, W.C.

    1980-07-01

    Forty patients with chemodectomas of the middle ear were seen at the University of Virginia Hospital from 1932 to 1978. Surgery, post-operative radiotherapy or radiotherapy alone were the treatment modalities employed depending on the extent of the disease. These have been reviewed with regard to the clinical presentation and results of treatment with long term follow-up of 1 to 30 years. An attempt was made to determine the optimum dose of radiotherapy based on our data and reported cases in the literature. The majority of patients complaining of tinnitus, otalgia and pulsation obtained significant if not complete relief of symptoms. Cranial nerve defects, however, ofter persisted after therapy. Tumor was considered to be controlled if there was no increase in its size or progression of symptoms. Tumor control was obtained in eight of 10 early patients but only in two of seven more patients with advanced disease with total resection. Control rate with post-operative radiotherapy after subtotal resection was 85%. Radiotherapy alone was used for inoperable or recurrent tumors and control was obtained in 88% of them. In addition to our data, the radiation dose used in over 200 patients reported in the literature was analyzed. There was only a 2% recurrence rate in patients who received 4000 rad/4 weeks or higher. Twenty-two percent of patients treated with less than 4000 rad developed recurrence. The tendency is to use a lower dose of postoperative treatment and a higher dose for gross inoperable tumors. 4000 rad/4 weeks seems to be adequate for control of postoperative residual disease and no more than 5000 rad/5 weeks are required even for advanced inoperable cases. By keeping the dose below 5000 rad/5 weeks, the incidence of complications such as brain necrosis is greatly decreased.

  6. Radiotherapy for Graves' disease. The possible role of low-dose radiotherapy.

    PubMed

    Arenas, Meritxell; Sabater, Sebastià; Jiménez, Pedro Lara; Rovirosa, Àngels; Biete, Albert; Linares, Victoria; Belles, Montse; Panés, Julià

    2016-01-01

    Immunomodulatory effects of low-dose radiotherapy (LD-RT) have been used for the treatment of several benign diseases, including arthrodegenerative and inflammatory pathologies. Graves' disease is an autoimmune disease and radiotherapy (RT) is a therapeutic option for ocular complications. The dose recommended in the clinical practice is 20 Gy (2 Gy/day). We hypothesized that lower doses (<10 Gy total dose, <1 Gy/day) could results in higher efficacy if we achieved anti-inflammatory and immunomodulatory effects of LD-RT. We review current evidence on the effects of RT in the treatment of Graves' disease and the possible use of LD-RT treatment strategy. PMID:27601953

  7. Low Dose, Low Energy 3d Image Guidance during Radiotherapy

    NASA Astrophysics Data System (ADS)

    Moore, C. J.; Marchant, T.; Amer, A.; Sharrock, P.; Price, P.; Burton, D.

    2006-04-01

    Patient kilo-voltage X-ray cone beam volumetric imaging for radiotherapy was first demonstrated on an Elekta Synergy mega-voltage X-ray linear accelerator. Subsequently low dose, reduced profile reconstruction imaging was shown to be practical for 3D geometric setup registration to pre-treatment planning images without compromising registration accuracy. Reconstruction from X-ray profiles gathered between treatment beam deliveries was also introduced. The innovation of zonal cone beam imaging promises significantly reduced doses to patients and improved soft tissue contrast in the tumour target zone. These developments coincided with the first dynamic 3D monitoring of continuous body topology changes in patients, at the moment of irradiation, using a laser interferometer. They signal the arrival of low dose, low energy 3D image guidance during radiotherapy itself.

  8. Integral dose: Comparison between four techniques for prostate radiotherapy

    PubMed Central

    Ślosarek, Krzysztof; Osewski, Wojciech; Grządziel, Aleksandra; Radwan, Michał; Dolla, Łukasz; Szlag, Marta; Stąpór-Fudzińska, Małgorzata

    2014-01-01

    Aim Comparisons of integral dose delivered to the treatment planning volume and to the whole patient body during stereotactic, helical and intensity modulated radiotherapy of prostate. Background Multifield techniques produce large volumes of low dose inside the patient body. Delivered dose could be the result of the cytotoxic injuries of the cells even away from the treatment field. We calculated the total dose absorbed in the patient body for four radiotherapy techniques to investigate whether some methods have a potential to reduce the exposure to the patient. Materials and methods We analyzed CyberKnife plans for 10 patients with localized prostate cancer. Five alternative plans for each patient were calculated with the VMAT, IMRT and TomoTherapy techniques. Alternative dose distributions were calculated to achieve the same coverage for PTV. Integral Dose formula was used to calculate the total dose delivered to the PTV and whole patient body. Results Analysis showed that the same amount of dose was deposited to the treated volume despite different methods of treatment delivery. The mean values of total dose delivered to the whole patient body differed significantly for each treatment technique. The highest integral dose in the patient's body was at the TomoTherapy and CyberKnife treatment session. VMAT was characterized by the lowest integral dose deposited in the patient body. Conclusions The highest total dose absorbed in normal tissue was observed with the use of a robotic radiosurgery system and TomoTherapy. These results demonstrate that the exposure of healthy tissue is a dosimetric factor which differentiates the dose delivery methods. PMID:25859398

  9. Computed tomography imaging-guided radiotherapy by targeting upconversion nanocubes with significant imaging and radiosensitization enhancements

    PubMed Central

    Xing, Huaiyong; Zheng, Xiangpeng; Ren, Qingguo; Bu, Wenbo; Ge, Weiqiang; Xiao, Qingfeng; Zhang, Shengjian; Wei, Chenyang; Qu, Haiyun; Wang, Zheng; Hua, Yanqing; Zhou, Liangping; Peng, Weijun; Zhao, Kuaile; Shi, Jianlin

    2013-01-01

    The clinical potentials of radiotherapy could not be achieved completely because of the inaccurate positioning and inherent radioresistance of tumours. In this study, a novel active-targeting upconversion theranostic agent (arginine-glycine-aspartic acid-labelled BaYbF5: 2% Er3+ nanocube) was developed for the first time to address these clinical demands. Heavy metal-based nanocubes (~10 nm) are potential theranostic agents with bifunctional features: computed tomography (CT) contrast agents for targeted tumour imaging and irradiation dose enhancers in tumours during radiotherapy. Remarkably, they showed low toxicity and excellent performance in active-targeting CT imaging and CT imaging-guided radiosensitizing therapy, which could greatly concentrate and enlarge the irradiation dose deposition in tumours to enhance therapeutic efficacy and minimize the damage to surrounding tissues. PMID:23624542

  10. On effective dose for radiotherapy based on doses to nontarget organs and tissues

    SciTech Connect

    Uselmann, Adam J. Thomadsen, Bruce R.

    2015-02-15

    Purpose: The National Council for Radiation Protection and Measurement (NCRP) published estimates for the collective population dose and the mean effective dose to the population of the United States from medical imaging procedures for 1980/1982 and for 2006. The earlier report ignored the effective dose from radiotherapy and the latter gave a cursory discussion of the topic but again did not include it in the population exposure for various reasons. This paper explains the methodology used to calculate the effective dose in due to radiotherapy procedures in the latter NCRP report and revises the values based on more detailed modeling. Methods: This study calculated the dose to nontarget organs from radiotherapy for reference populations using CT images and published peripheral dose data. Results: Using International Commission on Radiological Protection (ICRP) 60 weighting factors, the total effective dose to nontarget organs in radiotherapy patients is estimated as 298 ± 194 mSv per patient, while the U.S. population effective dose is 0.939 ± 0.610 mSv per person, with a collective dose of 283 000 ± 184 000 person Sv per year. Using ICRP 103 weighting factors, the effective dose is 281 ± 183 mSv per patient, 0.887 ± 0.577 mSv per person in the U.S., and 268 000 ± 174 000 person Sv per year. The uncertainty in the calculations is largely governed by variations in patient size, which was accounted for by considering a range of patient sizes and taking the average treatment site to nontarget organ distance. Conclusions: The methods used to estimate the effective doses from radiotherapy used in NCRP Report No. 160 have been explained and the values updated.

  11. Personalized estimation of dose to red bone marrow and the associated leukaemia risk attributable to pelvic kilo-voltage cone beam computed tomography scans in image-guided radiotherapy

    NASA Astrophysics Data System (ADS)

    Zhang, Yibao; Yan, Yulong; Nath, Ravinder; Bao, Shanglian; Deng, Jun

    2012-07-01

    The aim of this study is to investigate the imaging dose to red bone marrow (RBM) and the associated leukaemia risks attributable to pelvic kilo-voltage cone beam computed tomography (kVCBCT) scans in image-guided radiation therapy (IGRT). The RBM doses of 42 patients (age 2.7-86.4 years) were calculated using Monte Carlo simulations. The trabecular spongiosa was segmented to substitute RBM rather than the whole bone. Quantitative correlations between anthropometric variables such as age, physical bone density (PBD) and RBM dose were established. Personalized leukaemia risk was evaluated using an improved Boice model which included the age-associated RBM involvement. An incremental leukaemia risk of 29%-82% (mean = 45%) was found to be associated with 40 pelvic kVCBCT scans in the subject group used in a typical external beam radiation therapy course. Higher risks were observed in children. Due to the enhanced photoelectric effect in high atomic number materials, PBD was observed to strongly affect the RBM dose. Considerable overestimations (9%-42%, mean = 28%) were observed if the whole bone doses were used as surrogates of RBM doses. The personalized estimation of RBM dose and associated leukaemia risk caused by pelvic kVCBCT scans is clinically feasible with the proposed empirical models. Higher radiogenic cancer risks are associated with repeated kVCBCT scans in IGRT of cancer patients, especially children.

  12. Optimal radiotherapy dose schedules under parametric uncertainty

    NASA Astrophysics Data System (ADS)

    Badri, Hamidreza; Watanabe, Yoichi; Leder, Kevin

    2016-01-01

    We consider the effects of parameter uncertainty on the optimal radiation schedule in the context of the linear-quadratic model. Our interest arises from the observation that if inter-patient variability in normal and tumor tissue radiosensitivity or sparing factor of the organs-at-risk (OAR) are not accounted for during radiation scheduling, the performance of the therapy may be strongly degraded or the OAR may receive a substantially larger dose than the allowable threshold. This paper proposes a stochastic radiation scheduling concept to incorporate inter-patient variability into the scheduling optimization problem. Our method is based on a probabilistic approach, where the model parameters are given by a set of random variables. Our probabilistic formulation ensures that our constraints are satisfied with a given probability, and that our objective function achieves a desired level with a stated probability. We used a variable transformation to reduce the resulting optimization problem to two dimensions. We showed that the optimal solution lies on the boundary of the feasible region and we implemented a branch and bound algorithm to find the global optimal solution. We demonstrated how the configuration of optimal schedules in the presence of uncertainty compares to optimal schedules in the absence of uncertainty (conventional schedule). We observed that in order to protect against the possibility of the model parameters falling into a region where the conventional schedule is no longer feasible, it is required to avoid extremal solutions, i.e. a single large dose or very large total dose delivered over a long period. Finally, we performed numerical experiments in the setting of head and neck tumors including several normal tissues to reveal the effect of parameter uncertainty on optimal schedules and to evaluate the sensitivity of the solutions to the choice of key model parameters.

  13. Human Collagen Injections to Reduce Rectal Dose During Radiotherapy

    SciTech Connect

    Noyes, William R.; Hosford, Charles C.; Schultz, Steven E.

    2012-04-01

    Objectives: The continuing search for interventions, which address the incidence and grade of rectal toxicities associated with radiation treatment of prostate cancer, is a major concern. We are reporting an investigational trial using human collagen to increase the distance between the prostate and anterior rectal wall, thereby decreasing the radiation dose to the rectum. Methods: This is a pilot study evaluating the use of human collagen as a displacing agent for the rectal wall injected before starting a course of intensity-modulated radiotherapy (IMRT) for prostate cancer. Using a transperineal approach, 20 mL of human collagen was injected into the perirectal space in an outpatient setting. Computerized IMRT plans were performed pre- and postcollagen injection, and after a patient completed their radiotherapy, to determine radiation dose reduction to the rectum associated with the collagen injection. Computed tomography scans were performed 6 months and 12 months after completing their radiotherapy to evaluate absorption rate of the collagen. All patients were treated with IMRT to a dose of 75.6 Gy to the prostate. Results: Eleven patients were enrolled into the study. The injection of human collagen in the outpatient setting was well tolerated. The mean separation between the prostate and anterior rectum was 12.7 mm. The mean reduction in dose to the anterior rectal wall was 50%. All men denied any rectal symptoms during the study. Conclusions: The transperineal injection of human collagen for the purpose of tissue displacement is well tolerated in the outpatient setting. The increased separation between the prostate and rectum resulted in a significant decrease in radiation dose to the rectum while receiving IMRT and was associated with no rectal toxicities.

  14. Selecting radiotherapy dose distributions by means of constrained optimization problems.

    PubMed

    Alfonso, J C L; Buttazzo, G; García-Archilla, B; Herrero, M A; Núñez, L

    2014-05-01

    The main steps in planning radiotherapy consist in selecting for any patient diagnosed with a solid tumor (i) a prescribed radiation dose on the tumor, (ii) bounds on the radiation side effects on nearby organs at risk and (iii) a fractionation scheme specifying the number and frequency of therapeutic sessions during treatment. The goal of any radiotherapy treatment is to deliver on the tumor a radiation dose as close as possible to that selected in (i), while at the same time conforming to the constraints prescribed in (ii). To this day, considerable uncertainties remain concerning the best manner in which such issues should be addressed. In particular, the choice of a prescription radiation dose is mostly based on clinical experience accumulated on the particular type of tumor considered, without any direct reference to quantitative radiobiological assessment. Interestingly, mathematical models for the effect of radiation on biological matter have existed for quite some time, and are widely acknowledged by clinicians. However, the difficulty to obtain accurate in vivo measurements of the radiobiological parameters involved has severely restricted their direct application in current clinical practice.In this work, we first propose a mathematical model to select radiation dose distributions as solutions (minimizers) of suitable variational problems, under the assumption that key radiobiological parameters for tumors and organs at risk involved are known. Second, by analyzing the dependence of such solutions on the parameters involved, we then discuss the manner in which the use of those minimizers can improve current decision-making processes to select clinical dosimetries when (as is generally the case) only partial information on model radiosensitivity parameters is available. A comparison of the proposed radiation dose distributions with those actually delivered in a number of clinical cases strongly suggests that solutions of our mathematical model can be

  15. Absorbed dose behind eye shields during kilovoltage photon radiotherapy.

    PubMed

    Baker, C R; Luhana, F; Thomas, S J

    2002-08-01

    The absorbed dose at the position of the lens of the eye under lead or tungsten eye shields during kilovoltage photon radiotherapy is critically dependent not so much on the thickness of the eye shield itself as on the size of the treatment field and the diameter of the shield used. Whilst dose from primary photons is easily attenuated to relatively insignificant levels by a few millimetres of lead or tungsten, scattered photons from outside the shielded area can provide over 25% of the prescribed dose. Since backscatter factors do not increase monotonically with photon energy, it is not safe to assume that the highest photon energy used will provide the highest dose. A simple method to estimate the dose under an eye shield based on tabulated backscatter factors is shown. Measurements under commercially available eye shields were made to verify the expression and to determine the attenuation of primary photons. Predicted and measured absorbed dose under the eye shields were found to agree to within 1% of the prescribed dose. The relative dose due to primary photons beneath the eye shields was found to be less than 0.1% and 0.5 (+/-0.1)% for the 150 kV and 260 kV beams, respectively. This is considerably less than the dose from backscattered radiation. PMID:12153943

  16. Tomotherapy – a different way of dose delivery in radiotherapy

    PubMed Central

    Skórska, Małgorzata; Jodda, Agata; Ryczkowski, Adam; Kaźmierska, Joanna; Adamska, Krystyna; Karczewska-Dzionk, Aldona; Żmijewska-Tomczak, Małgorzata; Włodarczyk, Hanna

    2012-01-01

    Aim of the study Helical tomotherapy is one of the methods of radiotherapy. This method enables treatment implementation for a wide spectrum of clinical cases. The vast array of therapeutic uses of helical tomotherapy results directly from the method of dose delivery, which is significantly different from the classic method developed for conventional linear accelerators. The paper discusses the method of dose delivery by a tomotherapy machine. Moreover, an analysis and presentation of treatment plans was performed in order to show the therapeutic possibilities of the applied technology. Dose distributions were obtained for anaplastic medulloblastoma, multifocal metastases to brain, vulva cancer, tongue cancer, metastases to bones, and advanced skin cancer. Tomotherapy treatment plans were compared with conventional linear accelerator plans. Results Following the comparative analysis of tomotherapy and conventional linear accelerator plans, in each case we obtained the increase in dose distribution conformity manifested in greater homogeneity of doses in the radiation target area for anaplastic medulloblastoma, multifocal metastases to brain, vulva cancer, metastases to bones, and advanced skin cancer, and the reduction of doses in organs at risk (OAR) for anaplastic medulloblastoma, vulva cancer, tongue cancer, and advanced skin cancer. The time of treatment delivery in the case of a tomotherapy machine is comparable to the implementation of the plan prepared in intensity-modulated radiotherapy (IMRT) technique for a conventional linear accelerator. In the case of tomotherapy the application of a fractional dose was carried out in each case during one working period of the machine. For a conventional linear accelerator the total value of the fractional dose in the case of anaplastic medulloblastoma and metastases to bones was delivered using several treatment plans, for which a change of set-up was necessary during a fraction. Conclusion The obtained results

  17. Health technology assessment of image-guided radiotherapy (IGRT): A systematic review of current evidence

    PubMed Central

    Arabloo, Jalal; Hamouzadeh, Pejman; Mousavinezhad, Seyedeh Maryam; Mobinizadeh, Mohammadreza; Olyaeemanesh, Alireza; Pooyandjoo, Morvarid

    2016-01-01

    Background: Image-guided radiotherapy used multiple imaging during the radiation therapy course to improve the precision and accuracy of health care provider's treatment. Objectives: This study aims to assess the safety, effectiveness and economic aspects of image-guided radiation therapy for decision-making about this technology in Iran. Methods: In this study, the most important medical databases such as PubMed and Cochrane Library were searched until November 2014. The systematic reviews, health technology assessment reports and economic evaluation studies were included. The results of included studies were analyzed via the thematic synthesis. Results: Seven articles were included in the study. The results showed that image-guided radiation therapy, regardless of the imaging technique used in it, is associated with no major toxicity and has the potential to reduce the symptoms of poisoning. Using image-guided radiation therapy for prostate cancer resulted in substantial improvement in the quality of the received dose and optimal therapeutic dose of radiation to the targeted tumor while the radiation dose to the surrounding healthy tissues was minimal. Additionally, image-guided radiation therapy facilitated the diagnosis and management of exception deviations, including immediate changes and gross errors, weight loss, significant limbs deformity, systematic changes in the internal organs and changes in respiratory movements. Usage of image-guided radiation therapy for prostate cancer was associated with increased costs. Conclusion: Current available evidence suggests that the image-guided radiation therapy can reduce the amount of radiation to healthy tissue around the tumor and the toxicity associated with it. This can enhance the safe dose of radiation to the tumor and increase the likelihood of destruction of tumor. The current level of evidence required conducting further studies on the costs and effectiveness of this technology compared with conventional

  18. Feasibility of intensity-modulated and image-guided radiotherapy for locally advanced esophageal cancer

    PubMed Central

    2014-01-01

    Background In this study the feasibility of intensity-modulated radiotherapy (IMRT) and tomotherapy-based image-guided radiotherapy (IGRT) for locally advanced esophageal cancer was assessed. Methods A retrospective study of ten patients with locally advanced esophageal cancer who underwent concurrent chemotherapy with IMRT (1) and IGRT (9) was conducted. The gross tumor volume was treated to a median dose of 70 Gy (62.4-75 Gy). Results At a median follow-up of 14 months (1-39 months), three patients developed local failures, six patients developed distant metastases, and complications occurred in two patients (1 tracheoesophageal fistula, 1 esophageal stricture requiring repeated dilatations). No patients developed grade 3-4 pneumonitis or cardiac complications. Conclusions IMRT and IGRT may be effective for the treatment of locally advanced esophageal cancer with acceptable complications. PMID:24742268

  19. ORANGE: a Monte Carlo dose engine for radiotherapy.

    PubMed

    van der Zee, W; Hogenbirk, A; van der Marck, S C

    2005-02-21

    This study presents data for the verification of ORANGE, a fast MCNP-based dose engine for radiotherapy treatment planning. In order to verify the new algorithm, it has been benchmarked against DOSXYZ and against measurements. For the benchmarking, first calculations have been done using the ICCR-XIII benchmark. Next, calculations have been done with DOSXYZ and ORANGE in five different phantoms (one homogeneous, two with bone equivalent inserts and two with lung equivalent inserts). The calculations have been done with two mono-energetic photon beams (2 MeV and 6 MeV) and two mono-energetic electron beams (10 MeV and 20 MeV). Comparison of the calculated data (from DOSXYZ and ORANGE) against measurements was possible for a realistic 10 MV photon beam and a realistic 15 MeV electron beam in a homogeneous phantom only. For the comparison of the calculated dose distributions and dose distributions against measurements, the concept of the confidence limit (CL) has been used. This concept reduces the difference between two data sets to a single number, which gives the deviation for 90% of the dose distributions. Using this concept, it was found that ORANGE was always within the statistical bandwidth with DOSXYZ and the measurements. The ICCR-XIII benchmark showed that ORANGE is seven times faster than DOSXYZ, a result comparable with other accelerated Monte Carlo dose systems when no variance reduction is used. As shown for XVMC, using variance reduction techniques has the potential for further acceleration. Using modern computer hardware, this brings the total calculation time for a dose distribution with 1.5% (statistical) accuracy within the clinical range (less then 10 min). This means that ORANGE can be a candidate for a dose engine in radiotherapy treatment planning. PMID:15773624

  20. ORANGE: a Monte Carlo dose engine for radiotherapy

    NASA Astrophysics Data System (ADS)

    van der Zee, W.; Hogenbirk, A.; van der Marck, S. C.

    2005-02-01

    This study presents data for the verification of ORANGE, a fast MCNP-based dose engine for radiotherapy treatment planning. In order to verify the new algorithm, it has been benchmarked against DOSXYZ and against measurements. For the benchmarking, first calculations have been done using the ICCR-XIII benchmark. Next, calculations have been done with DOSXYZ and ORANGE in five different phantoms (one homogeneous, two with bone equivalent inserts and two with lung equivalent inserts). The calculations have been done with two mono-energetic photon beams (2 MeV and 6 MeV) and two mono-energetic electron beams (10 MeV and 20 MeV). Comparison of the calculated data (from DOSXYZ and ORANGE) against measurements was possible for a realistic 10 MV photon beam and a realistic 15 MeV electron beam in a homogeneous phantom only. For the comparison of the calculated dose distributions and dose distributions against measurements, the concept of the confidence limit (CL) has been used. This concept reduces the difference between two data sets to a single number, which gives the deviation for 90% of the dose distributions. Using this concept, it was found that ORANGE was always within the statistical bandwidth with DOSXYZ and the measurements. The ICCR-XIII benchmark showed that ORANGE is seven times faster than DOSXYZ, a result comparable with other accelerated Monte Carlo dose systems when no variance reduction is used. As shown for XVMC, using variance reduction techniques has the potential for further acceleration. Using modern computer hardware, this brings the total calculation time for a dose distribution with 1.5% (statistical) accuracy within the clinical range (less then 10 min). This means that ORANGE can be a candidate for a dose engine in radiotherapy treatment planning.

  1. Biological dose volume histograms during conformal hypofractionated accelerated radiotherapy for prostate cancer

    SciTech Connect

    Koukourakis, Michael I.; Abatzoglou, Ioannis; Touloupidis, Stavros; Manavis, Ioannis

    2007-01-15

    Radiobiological data suggest that prostate cancer has a low {alpha}/{beta} ratio. Large radiotherapy fractions may, therefore, prove more efficacious than standard radiotherapy, while radiotherapy acceleration should further improve control rates. This study describes the radiobiology of a conformal hypofractionated accelerated radiotherapy scheme for the treatment of high risk prostate cancer. Anteroposterior fields to the pelvis deliver a daily dose of 2.7 Gy, while lateral fields confined to the prostate and seminal vesicles deliver an additional daily dose of 0.7 Gy. Radiotherapy is accomplished within 19 days (15 fractions). Dose volume histograms, calculated for tissue specific {alpha}/{beta} ratios and time factors, predict a high biological dose to the prostate and seminal vesicles (77-93 Gy). The biological dose to normal pelvic tissues is maintained at standard levels. Radiobiological dosimetry suggests that, using hypofractionated and accelerated radiotherapy, high biological radiation dose can be given to the prostate without overdosing normal tissues.

  2. A Monte Carlo dose calculation tool for radiotherapy treatment planning

    NASA Astrophysics Data System (ADS)

    Ma, C.-M.; Li, J. S.; Pawlicki, T.; Jiang, S. B.; Deng, J.; Lee, M. C.; Koumrian, T.; Luxton, M.; Brain, S.

    2002-05-01

    A Monte Carlo user code, MCDOSE, has been developed for radiotherapy treatment planning (RTP) dose calculations. MCDOSE is designed as a dose calculation module suitable for adaptation to host RTP systems. MCDOSE can be used for both conventional photon/electron beam calculation and intensity modulated radiotherapy (IMRT) treatment planning. MCDOSE uses a multiple-source model to reconstruct the treatment beam phase space. Based on Monte Carlo simulated or measured beam data acquired during commissioning, source-model parameters are adjusted through an automated procedure. Beam modifiers such as jaws, physical and dynamic wedges, compensators, blocks, electron cut-outs and bolus are simulated by MCDOSE together with a 3D rectilinear patient geometry model built from CT data. Dose distributions calculated using MCDOSE agreed well with those calculated by the EGS4/DOSXYZ code using different beam set-ups and beam modifiers. Heterogeneity correction factors for layered-lung or layered-bone phantoms as calculated by both codes were consistent with measured data to within 1%. The effect of energy cut-offs for particle transport was investigated. Variance reduction techniques were implemented in MCDOSE to achieve a speedup factor of 10-30 compared to DOSXYZ.

  3. Single-Dose Versus Fractionated Stereotactic Radiotherapy for Brain Metastases

    SciTech Connect

    Kim, Yeon-Joo; Cho, Kwan Ho; Kim, Joo-Young; Lim, Young Kyung; Min, Hye Sook; Lee, Sang Hyun; Kim, Ho Jin; Gwak, Ho Shin; Yoo, Heon; Lee, Seung Hoon

    2011-10-01

    Purpose: To evaluate the efficacy of stereotactic radiotherapy in patients with brain metastases by comparing two different treatment regimens, single-dose radiosurgery (SRS) and fractionated stereotactic radiotherapy (FSRT). Methods and Materials: Between November 2003 and December 2008, 98 patients with brain metastases were included. Fifty-eight patients were treated with SRS, and forty were treated with FSRT. Fractionated stereotactic radiotherapy was used for large lesions or lesions located near critical structures. The median doses were 20 Gy for the SRS group and 36 Gy in 6 fractions for the FSRT group. Results: With a median follow-up period of 7 months, the median survival was 7 months for all patients, with a median of 6 months for the SRS group and 8 months for the FSRT group (p = 0.89). Local progression-free survival (LPFS) rates at 6 months and 1 year were 81% and 71%, respectively, for the SRS group and 97% and 69%, respectively, for the FSRT group (p = 0.31). Despite the fact that FSRT was used for large lesions and lesions in adverse locations, LPFS was not inferior to SRS. Toxicity was more frequently observed in the SRS group than in the FSRT group (17% vs. 5%, p = 0.05). Conclusions: Because patients treated with FSRT exhibited similar survival times and LPFS rates with a lower risk of toxicity in comparison to those treated with SRS, despite the fact that FSRT was used for large lesions and lesions in adverse locations, we find that FSRT can particularly be beneficial for patients with large lesions or lesions located near critical structures. Further investigation is warranted to determine the optimal dose/fractionation.

  4. Tissue doses from radiotherapy of cancer of the uterine cervix

    SciTech Connect

    Stovall, M.; Smith, S.A. ); Rosenstein, M.

    1989-09-01

    For use in an epidemiologic study of subsequent tumors, absorbed doses from brachytherapy and external beam radiotherapy were measured and calculated for various tissues of patients treated for cancer of the uterine cervix. External beams included orthovoltage x rays (1.9 and 3.0 mm Cu half-value layer), cobalt-60 gamma rays, 2 MV x rays, and 25 MV x rays. The brachytherapy sources were encapsulated radium. Measurements were made in an Alderson anthropomorphic phantom and a water phantom; calculations were made using a Monte Carlo technique or standard radiotherapy methods. Depending upon stage of disease and radiation energy, the absorbed doses (cGy) from typical treatment regimes to tissues of interest were: ovaries, 1400--5200; stomach, 130--320; kidneys, 120--310; pancreas, 100--260; lungs, 22--48; breasts, 19--52; thyroid, 6--17; salivary glands, 4--11; brain, 2--7, and total active bone marrow, 320--1100. The lower values of each range were for stage I of the disease.

  5. Measurement of neutron ambient dose equivalent in passive carbon-ion and proton radiotherapies

    SciTech Connect

    Yonai, Shunsuke; Matsufuji, Naruhiro; Kanai, Tatsuaki; Matsui, Yuki; Matsushita, Kaoru; Yamashita, Haruo; Numano, Masumi; Sakae, Takeji; Terunuma, Toshiyuki; Nishio, Teiji; Kohno, Ryosuke; Akagi, Takashi

    2008-11-15

    Secondary neutron ambient dose equivalents per the treatment absorbed dose in passive carbon-ion and proton radiotherapies were measured using a rem meter, WENDI-II at two carbon-ion radiotherapy facilities and four proton radiotherapy facilities in Japan. Our measured results showed that (1) neutron ambient dose equivalent in carbon-ion radiotherapy is lower than that in proton radiotherapy, and (2) the difference to the measured neutron ambient dose equivalents among the facilities is within a factor of 3 depending on the operational beam setting used at the facility and the arrangement of the beam line, regardless of the method for making a laterally uniform irradiation field: the double scattering method or the single-ring wobbling method. The reoptimization of the beam line in passive particle radiotherapy is an effective way to reduce the risk of secondary cancer because installing an adjustable precollimator and designing the beam line devices with consideration of their material, thickness and location, etc., can significantly reduce the neutron exposure. It was also found that the neutron ambient dose equivalent in passive particle radiotherapy is equal to or less than that in the photon radiotherapy. This result means that not only scanning particle radiotherapy but also passive particle radiotherapy can provide reduced exposure to normal tissues around the target volume without an accompanied increase in total body dose.

  6. Two non-parametric methods for derivation of constraints from radiotherapy dose-histogram data

    NASA Astrophysics Data System (ADS)

    Ebert, M. A.; Gulliford, S. L.; Buettner, F.; Foo, K.; Haworth, A.; Kennedy, A.; Joseph, D. J.; Denham, J. W.

    2014-07-01

    Dose constraints based on histograms provide a convenient and widely-used method for informing and guiding radiotherapy treatment planning. Methods of derivation of such constraints are often poorly described. Two non-parametric methods for derivation of constraints are described and investigated in the context of determination of dose-specific cut-points—values of the free parameter (e.g., percentage volume of the irradiated organ) which best reflect resulting changes in complication incidence. A method based on receiver operating characteristic (ROC) analysis and one based on a maximally-selected standardized rank sum are described and compared using rectal toxicity data from a prostate radiotherapy trial. Multiple test corrections are applied using a free step-down resampling algorithm, which accounts for the large number of tests undertaken to search for optimal cut-points and the inherent correlation between dose-histogram points. Both methods provide consistent significant cut-point values, with the rank sum method displaying some sensitivity to the underlying data. The ROC method is simple to implement and can utilize a complication atlas, though an advantage of the rank sum method is the ability to incorporate all complication grades without the need for grade dichotomization.

  7. Image-Guided Intensity-Modulated Photon Radiotherapy Using Multifractionated Regimen to Paraspinal Chordomas and Rare Sarcomas

    SciTech Connect

    Terezakis, Stephanie A. Lovelock, D. Michael; Bilsky, Mark H.; Hunt, Margaret A.; Zatcky, Joan N.P.; Yamada, Yoshiya

    2007-12-01

    Purpose: Image-guided intensity-modulated radiotherapy enables delivery of high-dose radiation to tumors close to the spinal cord. We report our experience with multifractionated regimens using image-guided intensity-modulated radiotherapy to treat gross paraspinal disease to doses beyond cord tolerance. Methods and Materials: We performed a retrospective review of 27 consecutive patients with partially resected or unresectable paraspinal tumors irradiated to >5,300 cGy in standard fractionation. Results: The median follow-up was 17.4 months (range, 2.1-47.3). Eighteen sarcomas, seven chordomas, and two ependymomas were treated. The median dose to the planning target volume was 6,600 cGy (range, 5,396-7,080) in 180- or 200-cGy fractions. The median planning target volume was 164 cm{sup 3} (range, 29-1,116). Seven patients developed recurrence at the treatment site (26%), and 6 of these patients had high-grade tumors. Three patients with recurrence had metastatic disease at the time of radiotherapy. The 2-year local control rate was 65%, and the 2-year overall survival rate was 79%. Of the 5 patients who died, 4 had metastatic disease at death. Twenty-three patients (84%) reported either no pain or improved pain at the last follow-up visit. Sixteen patients discontinued narcotic use after treatment (62.5%). Twenty-three patients (89%) had a stable or improved American Spine Injury Association score at the last follow-up visit. No patient experienced radiation-induced myelopathy. Conclusions: The dose to paraspinal tumors has traditionally been limited to respect cord tolerance. With image-guided intensity-modulated radiotherapy, greater doses of radiation delivered in multiple fractions can be prescribed with excellent target coverage, effective palliation, and acceptable toxicity and local control.

  8. Precision, high dose radiotherapy: helium ion treatment of uveal melanoma

    SciTech Connect

    Saunders, W.M.; Char, D.H.; Quivey, J.M.; Castro, J.R.; Chen, G.T.Y.; Collier, J.M.; Cartigny, A.; Blakely, E.A.; Lyman, J.T.; Zink, S.R.

    1985-02-01

    The authors report on 75 patients with uveal melanoma who were treated by placing the Bragg peak of a helium ion beam over the tumor volume. The technique localizes the high dose region very tightly around the tumor volume. This allows critical structures, such as the optic disc and the macula, to be excluded from the high dose region as long as they are 3 to 4 mm away from the edge of the tumor. Careful attention to tumor localization, treatment planning, patient immobilization and treatment verification is required. With a mean follow-up of 22 months (3 to 60 months) the authors have had only five patients with a local recurrence, all of whom were salvaged with another treatment. Pretreatment visual acuity has generally been preserved as long as the tumor edge is at least 4 mm away from the macula and optic disc. The only serious complication to date has been an 18% incidence of neovascular glaucoma in the patients treated at our highest dose level. Clinical results and details of the technique are presented to illustrate potential clinical precision in administering high dose radiotherapy with charged particles such as helium ions or protons.

  9. Kilovoltage Imaging Doses in the Radiotherapy of Pediatric Cancer Patients

    SciTech Connect

    Deng Jun; Chen Zhe; Roberts, Kenneth B.; Nath, Ravinder

    2012-04-01

    Purpose: To investigate doses induced by kilovoltage cone-beam computed tomography (kVCBCT) to pediatric cancer patients undergoing radiotherapy, as well as strategies for dose reduction. Methods and Materials: An EGS4 Monte Carlo code was used to calculate three-dimensional dose deposition due to kVCBCT on 4 pediatric cancer patients. Absorbed doses to various organs were analyzed for both half-fan and full-fan modes. Clinical conditions, such as distance from organ at risk (OAR) to CBCT field border, kV peak energy, and testicular shielding, were studied. Results: The mean doses induced by one CBCT scan operated at 125 kV in half-fan mode to testes, liver, kidneys, femoral heads, spinal cord, brain, eyes, lens, and optical nerves were 2.9, 4.7, 7.7, 10.5, 8.8, 7.6, 7.7, 7.8, and 7.2 cGy, respectively. Increasing the distances from OARs to CBCT field border greatly reduced the doses to OARs, ranging from 33% reduction for spinal cord to 2300% reduction for testes. As photon beam energy increased from 60 to 125 kV, the dose increase due to kVCBCT ranged from 170% for lens to 460% for brain and spinal cord. A testicular shielding made of 1-cm cerrobend could reduce CBCT doses down to 31%, 51%, 68%, and 82%, respectively, for 60, 80, 100, and 125 kV when the testes lay within the CBCT field. Conclusions: Generally speaking, kVCBCT deposits much larger doses to critical structures in children than in adults, usually by a factor of 2 to 3. Increasing the distances from OARs to CBCT field border greatly reduces doses to OARs. Depending on OARs, kVCBCT-induced doses increase linearly or exponentially with photon beam energy. Testicular shielding works more efficiently at lower kV energies. On the basis of our study, it is essential to choose an appropriate scanning protocol when kVCBCT is applied to pediatric cancer patients routinely.

  10. Recent Advances in Image-Guided Radiotherapy for Head and Neck Carcinoma

    PubMed Central

    Nath, Sameer K.; Simpson, Daniel R.; Rose, Brent S.; Sandhu, Ajay P.

    2009-01-01

    Radiotherapy has a well-established role in the management of head and neck cancers. Over the past decade, a variety of new imaging modalities have been incorporated into the radiotherapy planning and delivery process. These technologies are collectively referred to as image-guided radiotherapy and may lead to significant gains in tumor control and radiation side effect profiles. In the following review, these techniques as they are applied to head and neck cancer patients are described, and clinical studies analyzing their use in target delineation, patient positioning, and adaptive radiotherapy are highlighted. Finally, we conclude with a brief discussion of potential areas of further radiotherapy advancement. PMID:19644564

  11. [Prostate cancer external beam radiotherapy].

    PubMed

    de Crevoisier, R; Pommier, P; Latorzeff, I; Chapet, O; Chauvet, B; Hennequin, C

    2016-09-01

    The prostate external beam radiotherapy techniques are described, when irradiating the prostate or after prostatectomy, with and without pelvic lymph nodes. The following parts are presented: indications of radiotherapy, total dose and fractionation, planning CT image acquisition, volume of interest delineation (target volumes and organs at risk) and margins, Intensity modulated radiotherapy planning and corresponding dose-volume constraints, and finally Image guided radiotherapy. PMID:27516051

  12. Monte Carlo Study of Radiation Dose Enhancement by Gadolinium in Megavoltage and High Dose Rate Radiotherapy

    PubMed Central

    Zhang, Daniel G.; Feygelman, Vladimir; Moros, Eduardo G.; Latifi, Kujtim; Zhang, Geoffrey G.

    2014-01-01

    MRI is often used in tumor localization for radiotherapy treatment planning, with gadolinium (Gd)-containing materials often introduced as a contrast agent. Motexafin gadolinium is a novel radiosensitizer currently being studied in clinical trials. The nanoparticle technologies can target tumors with high concentration of high-Z materials. This Monte Carlo study is the first detailed quantitative investigation of high-Z material Gd-induced dose enhancement in megavoltage external beam photon therapy. BEAMnrc, a radiotherapy Monte Carlo simulation package, was used to calculate dose enhancement as a function of Gd concentration. Published phase space files for the TrueBeam flattening filter free (FFF) and conventional flattened 6MV photon beams were used. High dose rate (HDR) brachytherapy with Ir-192 source was also investigated as a reference. The energy spectra difference caused a dose enhancement difference between the two beams. Since the Ir-192 photons have lower energy yet, the photoelectric effect in the presence of Gd leads to even higher dose enhancement in HDR. At depth of 1.8 cm, the percent mean dose enhancement for the FFF beam was 0.38±0.12, 1.39±0.21, 2.51±0.34, 3.59±0.26, and 4.59±0.34 for Gd concentrations of 1, 5, 10, 15, and 20 mg/mL, respectively. The corresponding values for the flattened beam were 0.09±0.14, 0.50±0.28, 1.19±0.29, 1.68±0.39, and 2.34±0.24. For Ir-192 with direct contact, the enhanced were 0.50±0.14, 2.79±0.17, 5.49±0.12, 8.19±0.14, and 10.80±0.13. Gd-containing materials used in MRI as contrast agents can also potentially serve as radiosensitizers in radiotherapy. This study demonstrates that Gd can be used to enhance radiation dose in target volumes not only in HDR brachytherapy, but also in 6 MV FFF external beam radiotherapy, but higher than the currently used clinical concentration (>5 mg/mL) would be needed. PMID:25275550

  13. Equivalent dose and effective dose from stray radiation during passively scattered proton radiotherapy for prostate cancer

    NASA Astrophysics Data System (ADS)

    Fontenot, Jonas; Taddei, Phillip; Zheng, Yuanshui; Mirkovic, Dragan; Jordan, Thomas; Newhauser, Wayne

    2008-03-01

    Proton therapy reduces the integral therapeutic dose required for local control in prostate patients compared to intensity-modulated radiotherapy. One proposed benefit of this reduction is an associated decrease in the incidence of radiogenic secondary cancers. However, patients are also exposed to stray radiation during the course of treatment. The purpose of this study was to quantify the stray radiation dose received by patients during proton therapy for prostate cancer. Using a Monte Carlo model of a proton therapy nozzle and a computerized anthropomorphic phantom, we determined that the effective dose from stray radiation per therapeutic dose (E/D) for a typical prostate patient was approximately 5.5 mSv Gy-1. Sensitivity analysis revealed that E/D varied by ±30% over the interval of treatment parameter values used for proton therapy of the prostate. Equivalent doses per therapeutic dose (HT/D) in specific organs at risk were found to decrease with distance from the isocenter, with a maximum of 12 mSv Gy-1 in the organ closest to the treatment volume (bladder) and 1.9 mSv Gy-1 in the furthest (esophagus). Neutrons created in the nozzle predominated effective dose, though neutrons created in the patient contributed substantially to the equivalent dose in organs near the proton field. Photons contributed less than 15% to equivalent doses.

  14. Large Cohort Dose-Volume Response Analysis of Parotid Gland Function After Radiotherapy: Intensity-Modulated Versus Conventional Radiotherapy

    SciTech Connect

    Dijkema, Tim Terhaard, Chris H.J.; Roesink, Judith M.; Braam, Petra M.; Gils, Carla H. van; Moerland, Marinus A.; Raaijmakers, Cornelis P.J.

    2008-11-15

    Purpose: To compare parotid gland dose-volume response relationships in a large cohort of patients treated with intensity-modulated (IMRT) and conventional radiotherapy (CRT). Methods and materials: A total of 221 patients (64 treated with IMRT, 157 with CRT) with various head-and-neck malignancies were prospectively evaluated. The distribution of tumor subsites in both groups was unbalanced. Stimulated parotid flow rates were measured before and 6 weeks, 6 months, and 1 year after radiotherapy. Parotid gland dose-volume histograms were derived from computed tomography-based treatment planning. The normal tissue complication probability (NTCP) model proposed by Lyman was fit to the data. A complication was defined as stimulated parotid flow ratio <25% of the pretreatment flow rate. The relative risk of complications was determined for IMRT vs. CRT and adjusted for the mean parotid gland dose using Poisson regression modeling. Results: One year after radiotherapy, NTCP curves for IMRT and CRT were comparable with a TD{sub 50} (uniform dose leading to a 50% complication probability) of 38 and 40 Gy, respectively. Until 6 months after RT, corrected for mean dose, different complication probabilities existed for IMRT vs. CRT. The relative risk of a complication for IMRT vs. CRT after 6 weeks was 1.42 (95% CI 1.21-1.67), after 6 months 1.41 (95% CI; 1.12-1.77), and at 1 year 1.21 (95% CI 0.87-1.68), after correcting for mean dose. Conclusions: One year after radiotherapy, no difference existed in the mean dose-based NTCP curves for IMRT and CRT. Early after radiotherapy (up to 6 months) mean dose based (Lyman) models failed to fully describe the effects of radiotherapy on the parotid glands.

  15. Surface and superficial dose dosimetric verification for postmastectomy radiotherapy

    SciTech Connect

    Shiau, An-Cheng; Chiu, Min-Chi; Chen, Tung-Ho; Chiou, Jeng-Fong; Shueng, Pei-Wei; Chen, Shang-Wen; Chen, Wei-Li; Kuan, Wei-Peng

    2012-01-01

    In patients given postmastectomy radiotherapy (PMRT), the chest wall is a very thin layer of soft tissue with a low-density lung tissue behind. Chest wall treated in this situation with a high-energy photon beam presents a high dosimetric uncertainty region for both calculation and measurement. The purpose of this study was to measure and to evaluate the surface and superficial doses for patients requiring PMRT with different treatment techniques. An elliptic cylinder cork and superflab boluses were used to simulate the lung and the chest wall, respectively. Sets of computed tomography (CT) images with different chest wall thicknesses were acquired for the study phantom. Hypothetical clinical target volumes (CTVs) were outlined and modified to fit a margin of 1-3 mm, depending on the chest wall thickness, away from the surface for the sets of CT images. The planning target volume (PTV) was initially created by expanding an isotropic 3-mm margin from the CTV, and then a margin of 3 mm was shrunk from the phantom surface to avoid artifact-driven results in the beam-let intensity. Treatment techniques using a pair of tangential wedged fields (TWFs) and 4-field intensity-modulated radiation therapy (IMRT) were designed with a prescribed fraction dose (D{sub p}) of 180 cGy. Superficial dose profiles around the phantom circumference at depths of 0, 1, 2, 3, and 5 mm were obtained for each treatment technique using radiochromic external beam therapy (EBT) films. EBT film exhibits good characteristics for dose measurements in the buildup region. Underdoses at the median and lateral regions of the TWF plans were shown. The dose profiles at shallow depths for the TWF plans show a dose buildup about 3 mm at the median and lateral tangential incident regions with a surface dose of about 52% of D{sub p}. The dose was gradually increased toward the most obliquely tangential angle with a maximum dose of about 118% of D{sub p.} Dose profiles were more uniform in the PTV region for

  16. A Software App for Radiotherapy with In-situ Dose-painting using high Z nanoparticles

    PubMed Central

    Jermoumi, M; Yucel, A; Hao, Y; Cifter, G; Sajo, E; Ngwa, W

    2016-01-01

    The purpose of this work is to develop an user friendly and free-to-download application software that can be employed for modeling Radiotherapy with In-situ Dose-painting (RAID) using high-Z nanoparticles (HZNPs). The RAID APP is software program written in Matlab (Mathworks, Natick, MA, USA) based on deterministic code developed to simulate the space-time intra-tumor HZNPs biodistribution within the tumor, and the corresponding dose enhancement in response to low dose rate (LDR) brachytherapy of I-125, Pd-102, Cs-131 and kilovoltage x-rays such as 50 keV and 100 keV. Through the GUI of RAID APP, the user will be directed to different features to compute various parameters related to the dose enhancement and the biodistribution of NPs within high risk tumor sub-volumes. The software was developed as tool for research purposes with potential for subsequent development to guide dose-painting treatment planning using radiosensitizers such as gold (Au) and platinum (Pt).

  17. An image guided small animal stereotactic radiotherapy system.

    PubMed

    Sha, Hao; Udayakumar, Thirupandiyur S; Johnson, Perry B; Dogan, Nesrin; Pollack, Alan; Yang, Yidong

    2016-04-01

    Small animal radiotherapy studies should be performed preferably on irradiators capable of focal tumor irradiation and healthy tissue sparing. In this study, an image guided small animal arc radiation treatment system (iSMAART) was developed which can achieve highly precise radiation targeting through the utilization of onboard cone beam computed tomography (CBCT) guidance. The iSMAART employs a unique imaging and radiation geometry where animals are positioned upright. It consists of a stationary x-ray tube, a stationary flat panel detector, and a rotatable and translational animal stage. System performance was evaluated in regards to imaging, image guidance, animal positioning, and radiation targeting using phantoms and tumor bearing animals. The onboard CBCT achieved good signal, contrast, and sub-millimeter spatial resolution. The iodine contrast CBCT accurately delineated orthotopic prostate tumors. Animal positioning was evaluated with ~0.3 mm vertical displacement along superior-inferior direction. The overall targeting precision was within 0.4 mm. Stereotactic radiation beams conformal to tumor targets can be precisely delivered from multiple angles surrounding the animal. The iSMAART allows radiobiology labs to utilize an image guided precision radiation technique that can focally irradiate tumors while sparing healthy tissues at an affordable cost. PMID:26958942

  18. An image guided small animal stereotactic radiotherapy system

    PubMed Central

    Sha, Hao; Udayakumar, Thirupandiyur S.; Johnson, Perry B.; Dogan, Nesrin; Pollack, Alan; Yang, Yidong

    2016-01-01

    Small animal radiotherapy studies should be performed preferably on irradiators capable of focal tumor irradiation and healthy tissue sparing. In this study, an image guided small animal arc radiation treatment system (iSMAART) was developed which can achieve highly precise radiation targeting through the utilization of onboard cone beam computed tomography (CBCT) guidance. The iSMAART employs a unique imaging and radiation geometry where animals are positioned upright. It consists of a stationary x-ray tube, a stationary flat panel detector, and a rotatable and translational animal stage. System performance was evaluated in regards to imaging, image guidance, animal positioning, and radiation targeting using phantoms and tumor bearing animals. The onboard CBCT achieved good signal, contrast, and sub-millimeter spatial resolution. The iodine contrast CBCT accurately delineated orthotopic prostate tumors. Animal positioning was evaluated with ∼0.3 mm vertical displacement along superior-inferior direction. The overall targeting precision was within 0.4 mm. Stereotactic radiation beams conformal to tumor targets can be precisely delivered from multiple angles surrounding the animal. The iSMAART allows radiobiology labs to utilize an image guided precision radiation technique that can focally irradiate tumors while sparing healthy tissues at an affordable cost. PMID:26958942

  19. The CNAO dose delivery system for modulated scanning ion beam radiotherapy

    SciTech Connect

    Giordanengo, S.; Marchetto, F.; Garella, M. A.; Donetti, M.; Bourhaleb, F.; Monaco, V.; Hosseini, M. A.; Peroni, C.; Sacchi, R.; Cirio, R.; Ciocca, M.; Mirandola, A.

    2015-01-15

    Purpose: This paper describes the system for the dose delivery currently used at the Centro Nazionale di Adroterapia Oncologica (CNAO) for ion beam modulated scanning radiotherapy. Methods: CNAO Foundation, Istituto Nazionale di Fisica Nucleare and University of Torino have designed, built, and commissioned a dose delivery system (DDS) to monitor and guide ion beams accelerated by a dedicated synchrotron and to distribute the dose with a full 3D scanning technique. Protons and carbon ions are provided for a wide range of energies in order to cover a sizable span of treatment depths. The target volume, segmented in several layers orthogonally to the beam direction, is irradiated by thousands of pencil beams which must be steered and held to the prescribed positions until the prescribed number of particles has been delivered. For the CNAO beam lines, these operations are performed by the DDS. The main components of this system are two independent beam monitoring detectors, called BOX1 and BOX2, interfaced with two control systems performing the tasks of real-time fast and slow control, and connected to the scanning magnets and the beam chopper. As a reaction to any condition leading to a potential hazard, a DDS interlock signal is sent to the patient interlock system which immediately stops the irradiation. The essential tasks and operations performed by the DDS are described following the data flow from the treatment planning system through the end of the treatment delivery. Results: The ability of the DDS to guarantee a safe and accurate treatment was validated during the commissioning phase by means of checks of the charge collection efficiency, gain uniformity of the chambers, and 2D dose distribution homogeneity and stability. A high level of reliability and robustness has been proven by three years of system activity needing rarely more than regular maintenance and working with 100% uptime. Four identical and independent DDS devices have been tested showing

  20. Evaluation of volume change in rectum and bladder during application of image-guided radiotherapy for prostate carcinoma

    NASA Astrophysics Data System (ADS)

    Luna, J. A.; Rojas, J. I.

    2016-07-01

    All prostate cancer patients from Centro Médico Radioterapia Siglo XXI receive Volumetric Modulated Arc Therapy (VMAT). This therapy uses image-guided radiotherapy (IGRT) with the Cone Beam Computed Tomography (CBCT). This study compares the planned dose in the reference CT image against the delivered dose recalculate in the CBCT image. The purpose of this study is to evaluate the anatomic changes and related dosimetric effect based on weekly CBCT directly for patients with prostate cancer undergoing volumetric modulated arc therapy (VMAT) treatment. The collected data were analyzed using one-way ANOVA.

  1. Efficacy of Dose-Escalated Radiotherapy for Recurrent Colorectal Cancer

    PubMed Central

    Jo, Sunmi; Park, Sung-Kwang; Kim, Jin-Young; Kim, Hyun Jung; Lee, Yun-Han; Oh, Won Yong; Cho, Heunglae; Ahn, Ki Jung

    2016-01-01

    Purpose This study aimed to evaluate the effects of radiotherapy (RT) on progression-free survival (PFS) for patients with recurrent colorectal cancer. Methods We reviewed the records of 22 patients with recurrent colorectal cancer treated with RT between 2008 and 2014. The median radiation dose for recurrent disease was 57.6 Gy (range, 45–75.6 Gy). Patients were divided into 2 groups according to the type of RT: patients underwent RT without previous history of irradiation (n = 14) and those treated with secondary RT (reirradiation: n = 8) at the time of recurrence. Results The median follow-up period was 24.9 months (range, 4.5–66.6 months). Progression was observed in 14 patients (including 8 with loco-regional failure and 9 with distant metastases). Distant metastases were related to the RT dose (<70 Gy, P = 0.031). The 2-year loco-regional control (LRC), PFS, and overall survival (OS) rates were 74.6%, 45.1%, and 82.0%, respectively. The LRC rate was not different between the patients treated with RT for the first time and those treated with reirradiation (P = 0.101, 2-year LRC 79.5% vs. 41.7%). However, reirradiation was related to poor PFS (P = 0.022) and OS (P = 0.002). An escalated RT dose (≥70 Gy) was associated with a higher PFS (P = 0.014, 2-year PFS 63.5% vs. 20.8%). Conclusion Salvage RT for locally recurrent colorectal cancer can be offered when surgery is impossible. Dose-escalated RT shows a possible benefit in reducing the risk of progression. PMID:27218097

  2. Image-Guided Radiotherapy in Near Real Time With Intensity-Modulated Radiotherapy Megavoltage Treatment Beam Imaging

    SciTech Connect

    Mao Weihua Hsu, Annie; Riaz, Nadeem; Lee, Louis; Wiersma, Rodney; Luxton, Gary; King, Christopher; Xing Lei; Solberg, Timothy

    2009-10-01

    Purpose: To utilize image-guided radiotherapy (IGRT) in near real time by obtaining and evaluating the online positions of implanted fiducials from continuous electronic portal imaging device (EPID) imaging of prostate intensity-modulated radiotherapy (IMRT) delivery. Methods and Materials: Upon initial setup using two orthogonal images, the three-dimensional (3D) positions of all implanted fiducial markers are obtained, and their expected two-dimensional (2D) locations in the beam's-eye-view (BEV) projection are calculated for each treatment field. During IMRT beam delivery, EPID images of the megavoltage treatment beam are acquired in cine mode and subsequently analyzed to locate 2D locations of fiducials in the BEV. Simultaneously, 3D positions are estimated according to the current EPID image, information from the setup portal images, and images acquired at other gantry angles (the completed treatment fields). The measured 2D and 3D positions of each fiducial are compared with their expected 2D and 3D setup positions, respectively. Any displacements larger than a predefined tolerance may cause the treatment system to suspend the beam delivery and direct the therapists to reposition the patient. Results: Phantom studies indicate that the accuracy of 2D BEV and 3D tracking are better than 1 mm and 1.4 mm, respectively. A total of 7330 images from prostate treatments were acquired and analyzed, showing a maximum 2D displacement of 6.7 mm and a maximum 3D displacement of 6.9 mm over 34 fractions. Conclusions: This EPID-based, real-time IGRT method can be implemented on any external beam machine with portal imaging capabilities without purchasing any additional equipment, and there is no extra dose delivered to the patient.

  3. Magnetic Resonance Lymphography-Guided Selective High-Dose Lymph Node Irradiation in Prostate Cancer

    SciTech Connect

    Meijer, Hanneke J.M.; Debats, Oscar A.; Kunze-Busch, Martina; Kollenburg, Peter van; Leer, Jan Willem; Witjes, J. Alfred; Kaanders, Johannes H.A.M.; Barentsz, Jelle O.; Lin, Emile N.J.Th. van

    2012-01-01

    Purpose: To demonstrate the feasibility of magnetic resonance lymphography (MRL) -guided delineation of a boost volume and an elective target volume for pelvic lymph node irradiation in patients with prostate cancer. The feasibility of irradiating these volumes with a high-dose boost to the MRL-positive lymph nodes in conjunction with irradiation of the prostate using intensity-modulated radiotherapy (IMRT) was also investigated. Methods and Materials: In 4 prostate cancer patients with a high risk of lymph node involvement but no enlarged lymph nodes on CT and/or MRI, MRL detected pathological lymph nodes in the pelvis. These lymph nodes were identified and delineated on a radiotherapy planning CT to create a boost volume. Based on the location of the MRL-positive lymph nodes, the standard elective pelvic target volume was individualized. An IMRT plan with a simultaneous integrated boost (SIB) was created with dose prescriptions of 42 Gy to the pelvic target volume, a boost to 60 Gy to the MRL-positive lymph nodes, and 72 Gy to the prostate. Results: All MRL-positive lymph nodes could be identified on the planning CT. This information could be used to delineate a boost volume and to individualize the pelvic target volume for elective irradiation. IMRT planning delivered highly acceptable radiotherapy plans with regard to the prescribed dose levels and the dose to the organs at risk (OARs). Conclusion: MRL can be used to select patients with limited lymph node involvement for pelvic radiotherapy. MRL-guided delineation of a boost volume and an elective pelvic target volume for selective high-dose lymph node irradiation with IMRT is feasible. Whether this approach will result in improved outcome for these patients needs to be investigated in further clinical studies.

  4. Absolute dose calculations for Monte Carlo simulations of radiotherapy beams.

    PubMed

    Popescu, I A; Shaw, C P; Zavgorodni, S F; Beckham, W A

    2005-07-21

    Monte Carlo (MC) simulations have traditionally been used for single field relative comparisons with experimental data or commercial treatment planning systems (TPS). However, clinical treatment plans commonly involve more than one field. Since the contribution of each field must be accurately quantified, multiple field MC simulations are only possible by employing absolute dosimetry. Therefore, we have developed a rigorous calibration method that allows the incorporation of monitor units (MU) in MC simulations. This absolute dosimetry formalism can be easily implemented by any BEAMnrc/DOSXYZnrc user, and applies to any configuration of open and blocked fields, including intensity-modulated radiation therapy (IMRT) plans. Our approach involves the relationship between the dose scored in the monitor ionization chamber of a radiotherapy linear accelerator (linac), the number of initial particles incident on the target, and the field size. We found that for a 10 x 10 cm2 field of a 6 MV photon beam, 1 MU corresponds, in our model, to 8.129 x 10(13) +/- 1.0% electrons incident on the target and a total dose of 20.87 cGy +/- 1.0% in the monitor chambers of the virtual linac. We present an extensive experimental verification of our MC results for open and intensity-modulated fields, including a dynamic 7-field IMRT plan simulated on the CT data sets of a cylindrical phantom and of a Rando anthropomorphic phantom, which were validated by measurements using ionization chambers and thermoluminescent dosimeters (TLD). Our simulation results are in excellent agreement with experiment, with percentage differences of less than 2%, in general, demonstrating the accuracy of our Monte Carlo absolute dose calculations. PMID:16177516

  5. Absolute dose calculations for Monte Carlo simulations of radiotherapy beams

    NASA Astrophysics Data System (ADS)

    Popescu, I. A.; Shaw, C. P.; Zavgorodni, S. F.; Beckham, W. A.

    2005-07-01

    Monte Carlo (MC) simulations have traditionally been used for single field relative comparisons with experimental data or commercial treatment planning systems (TPS). However, clinical treatment plans commonly involve more than one field. Since the contribution of each field must be accurately quantified, multiple field MC simulations are only possible by employing absolute dosimetry. Therefore, we have developed a rigorous calibration method that allows the incorporation of monitor units (MU) in MC simulations. This absolute dosimetry formalism can be easily implemented by any BEAMnrc/DOSXYZnrc user, and applies to any configuration of open and blocked fields, including intensity-modulated radiation therapy (IMRT) plans. Our approach involves the relationship between the dose scored in the monitor ionization chamber of a radiotherapy linear accelerator (linac), the number of initial particles incident on the target, and the field size. We found that for a 10 × 10 cm2 field of a 6 MV photon beam, 1 MU corresponds, in our model, to 8.129 × 1013 ± 1.0% electrons incident on the target and a total dose of 20.87 cGy ± 1.0% in the monitor chambers of the virtual linac. We present an extensive experimental verification of our MC results for open and intensity-modulated fields, including a dynamic 7-field IMRT plan simulated on the CT data sets of a cylindrical phantom and of a Rando anthropomorphic phantom, which were validated by measurements using ionization chambers and thermoluminescent dosimeters (TLD). Our simulation results are in excellent agreement with experiment, with percentage differences of less than 2%, in general, demonstrating the accuracy of our Monte Carlo absolute dose calculations.

  6. Daily variations in delivered doses in patients treated with radiotherapy for localized prostate cancer

    SciTech Connect

    Kupelian, Patrick A. . E-mail: patrick.kupelian@orhs.org; Langen, Katja M.; Zeidan, Omar A.; Meeks, Sanford L.; Willoughby, Twyla R.; Wagner, Thomas H.; Jeswani, Sam; Ruchala, Kenneth J.; Haimerl, Jason; Olivera, Gustavo H.

    2006-11-01

    Purpose: The aim of this work was to study the variations in delivered doses to the prostate, rectum, and bladder during a full course of image-guided external beam radiotherapy. Methods and Materials: Ten patients with localized prostate cancer were treated with helical tomotherapy to 78 Gy at 2 Gy per fraction in 39 fractions. Daily target localization was performed using intraprostatic fiducials and daily megavoltage pelvic computed tomography (CT) scans, resulting in a total of 390 CT scans. The prostate, rectum, and bladder were manually contoured on each CT by a single physician. Daily dosimetric analysis was performed with dose recalculation. The study endpoints were D95 (dose to 95% of the prostate), rV2 (absolute rectal volume receiving 2 Gy), and bV2 (absolute bladder volume receiving 2 Gy). Results: For the entire cohort, the average D95 ({+-}SD) was 2.02 {+-} 0.04 Gy (range, 1.79-2.20 Gy). The average rV2 ({+-}SD) was 7.0 {+-} 8.1 cc (range, 0.1-67.3 cc). The average bV2 ({+-}SD) was 8.7 {+-} 6.8 cc (range, 0.3-36.8 cc). Unlike doses for the prostate, there was significant daily variation in rectal and bladder doses, mostly because of variations in volume and shape of these organs. Conclusion: Large variations in delivered doses to the rectum and bladder can be documented with daily megavoltage CT scans. Image guidance for the targeting of the prostate, even with intraprostatic fiducials, does not take into account the variation in actual rectal and bladder doses. The clinical impact of techniques that take into account such dosimetric parameters in daily patient set-ups should be investigated.

  7. Fluoroscopic tumor tracking for image-guided lung cancer radiotherapy

    NASA Astrophysics Data System (ADS)

    Lin, Tong; Cerviño, Laura I.; Tang, Xiaoli; Vasconcelos, Nuno; Jiang, Steve B.

    2009-02-01

    Accurate lung tumor tracking in real time is a keystone to image-guided radiotherapy of lung cancers. Existing lung tumor tracking approaches can be roughly grouped into three categories: (1) deriving tumor position from external surrogates; (2) tracking implanted fiducial markers fluoroscopically or electromagnetically; (3) fluoroscopically tracking lung tumor without implanted fiducial markers. The first approach suffers from insufficient accuracy, while the second may not be widely accepted due to the risk of pneumothorax. Previous studies in fluoroscopic markerless tracking are mainly based on template matching methods, which may fail when the tumor boundary is unclear in fluoroscopic images. In this paper we propose a novel markerless tumor tracking algorithm, which employs the correlation between the tumor position and surrogate anatomic features in the image. The positions of the surrogate features are not directly tracked; instead, we use principal component analysis of regions of interest containing them to obtain parametric representations of their motion patterns. Then, the tumor position can be predicted from the parametric representations of surrogates through regression. Four regression methods were tested in this study: linear and two-degree polynomial regression, artificial neural network (ANN) and support vector machine (SVM). The experimental results based on fluoroscopic sequences of ten lung cancer patients demonstrate a mean tracking error of 2.1 pixels and a maximum error at a 95% confidence level of 4.6 pixels (pixel size is about 0.5 mm) for the proposed tracking algorithm.

  8. A Study of Image-Guided Intensity-Modulated Radiotherapy With Fiducials for Localized Prostate Cancer Including Pelvic Lymph Nodes

    SciTech Connect

    Hsu, Annie; Pawlicki, Todd; Luxton, Gary; Hara, Wendy; King, Christopher R. . E-mail: crking@stanford.edu

    2007-07-01

    Purpose: To study the impact on nodal coverage and dose to fixed organs at risk when using daily fiducial localization of the prostate to deliver intensity-modulated radiotherapy (IMRT). Methods and Materials: Five patients with prostate cancer in whom prostate and pelvic nodes were irradiated with IMRT were studied. Dose was prescribed such that 95% of the prostate planning target volume (PTV) and 90% of the nodal PTV were covered. Random and systematic prostate displacements in the anterior-posterior, superior-inferior, and left-right directions were simulated to shift the original isocenter of the IMRT plan. The composite dose during the course of treatment was calculated. Results: Compared with a static setup, simulating random shifts reduced dose by less than 1.5% for nodal hotspot (i.e., dose to 1 cm{sup 3}), by less than 1% for the 90% nodal PTV coverage, and by less than 0.5% for the nodal mean dose. Bowel and femoral head hotspots were reduced by less than 1.5% and 2%, respectively. A 10-mm systematic offset reduced nodal coverage by up to 10%. Conclusion: The use of prostate fiducials for daily localization during IMRT treatment results in negligible changes in dose coverage of pelvic nodes or normal tissue sparing in the absence of a significant systematic offset. This offers a simple and practical solution to the problem of image-guided radiotherapy for prostate cancer when including pelvic nodes.

  9. Phase II Trial of Concurrent Sunitinib and Image-Guided Radiotherapy for Oligometastases

    PubMed Central

    Tong, Charles C. L.; Ko, Eric C.; Sung, Max W.; Cesaretti, Jamie A.; Stock, Richard G.; Packer, Stuart H.; Forsythe, Kevin; Genden, Eric M.; Schwartz, Myron; Lau, K. H. Vincent; Galsky, Matthew; Ozao-Choy, Junko; Chen, Shu-hsia; Kao, Johnny

    2012-01-01

    Background Preclinical data suggest that sunitinib enhances the efficacy of radiotherapy. We tested the combination of sunitinib and hypofractionated image-guided radiotherapy (IGRT) in a cohort of patients with historically incurable distant metastases. Methods Twenty five patients with oligometastases, defined as 1–5 sites of active disease on whole body imaging, were enrolled in a phase II trial from 2/08 to 9/10. The most common tumor types treated were head and neck, liver, lung, kidney and prostate cancers. Patients were treated with the recommended phase II dose of 37.5 mg daily sunitinib (days 1–28) and IGRT 50 Gy (days 8–12 and 15–19). Maintenance sunitinib was used in 33% of patients. Median follow up was 17.5 months (range, 0.7 to 37.4 months). Results The 18-month local control, distant control, progression-free survival (PFS) and overall survival (OS) were 75%, 52%, 56% and 71%, respectively. At last follow-up, 11 (44%) patients were alive without evidence of disease, 7 (28%) were alive with distant metastases, 3 (12%) were dead from distant metastases, 3 (12%) were dead from comorbid illness, and 1 (4%) was dead from treatment-related toxicities. The incidence of acute grade ≥ 3 toxicities was 28%, most commonly myelosuppression, bleeding and abnormal liver function tests. Conclusions Concurrent sunitinib and IGRT achieves major clinical responses in a subset of patients with oligometastases. Trial Registration ClinicalTrials.gov NCT00463060 PMID:22761653

  10. Calcifications Are Potential Surrogates for Prostate Localization in Image-Guided Radiotherapy

    SciTech Connect

    Zeng, Grace G. McGowan, Tom S.; Larsen, Tessa M.; Bruce, Lisa M.; Moran, Natasha K.; Tsao, Jonathan R.; MacPherson, Miller S.

    2008-11-15

    Purpose: To investigate the feasibility of using calcifications as surrogates for the prostate position during cone-beam computed tomography (CBCT) image-guided radiotherapy. Methods and Materials: The twice-weekly CBCT images taken during the treatment course of 4 patients were retrospectively studied for the stability of the calcifications. The geometric center of three fiducial markers was used as the reference. The planning CT images of 131 prostate patients recently treated with external beam radiotherapy at our center were reviewed to estimate the calcification occurrence rate. Analysis was conducted using the Varian Eclipse treatment planning system. Two patients were treated using prostate calcifications as the landmark in on-line registration. Both the Varian standard and the low-dose CBCT modes were used for imaging. Results: The calcifications were found to be stable during the treatment course. At the 95% confidence interval, the difference between the distance from an identified calcification to the fiducial markers on CBCT and the distance on the planning CT scans was 0.2 {+-} 2.0 mm, 0.8 {+-} 2.2 mm, and 0.4 {+-} 2.4 mm in the left-right, anteroposterior, and superoinferior direction, respectively. Of the 131 patients, 46 (35%) had well-defined calcifications either inside the prostate or near the borders. Our experience in treating the first 2 patients demonstrated that the calcifications are easily distinguished on low-dose scans and that calcification registration can be precisely performed. Conclusion: The results of our study have shown that calcifications can be reliable markers of prostate position and allow for precise image guidance with a low-imaging dose. With this approach, potentially about one-third of prostate patients could benefit from precise image guidance without the invasive use of markers.

  11. Use of image guided radiation therapy techniques and imaging dose measurement at Indian hospitals: A survey

    PubMed Central

    Deshpande, Sudesh; Dhote, D. S.; Kumar, Rajesh; Naidu, Suresh; Sutar, A.; Kannan, V.

    2015-01-01

    A national survey was conducted to obtain information about the use of image-guided radiotherapy (IGRT) techniques and IGRT dose measurement methods being followed at Indian radiotherapy centers. A questionnaire containing parameters relevant to use of IGRT was prepared to collect the information pertaining to (i) availability and type of IGRT delivery system, (ii) frequency of image acquisition protocol and utilization of these images for different purpose, and (iii) imaging dose measurement. The questionnaire was circulated to 75 hospitals in the country having IGRT facility, and responses of 51 centers were received. Survey results showed that among surveyed hospitals, 86% centers have IGRT facility, 78% centers have kilo voltage three-dimensional volumetric imaging. 75% of hospitals in our study do not perform computed tomography dose index measurements and 89% of centers do not perform patient dose measurements. Moreover, only 29% physicists believe IGRT dose is additional radiation burden to patient. This study has brought into focus the need to design a national protocol for IGRT dose measurement and development of indigenous tools to perform IGRT dose measurements. PMID:26865758

  12. Use of image guided radiation therapy techniques and imaging dose measurement at Indian hospitals: A survey.

    PubMed

    Deshpande, Sudesh; Dhote, D S; Kumar, Rajesh; Naidu, Suresh; Sutar, A; Kannan, V

    2015-01-01

    A national survey was conducted to obtain information about the use of image-guided radiotherapy (IGRT) techniques and IGRT dose measurement methods being followed at Indian radiotherapy centers. A questionnaire containing parameters relevant to use of IGRT was prepared to collect the information pertaining to (i) availability and type of IGRT delivery system, (ii) frequency of image acquisition protocol and utilization of these images for different purpose, and (iii) imaging dose measurement. The questionnaire was circulated to 75 hospitals in the country having IGRT facility, and responses of 51 centers were received. Survey results showed that among surveyed hospitals, 86% centers have IGRT facility, 78% centers have kilo voltage three-dimensional volumetric imaging. 75% of hospitals in our study do not perform computed tomography dose index measurements and 89% of centers do not perform patient dose measurements. Moreover, only 29% physicists believe IGRT dose is additional radiation burden to patient. This study has brought into focus the need to design a national protocol for IGRT dose measurement and development of indigenous tools to perform IGRT dose measurements. PMID:26865758

  13. [Which rules apply to hypofractionated radiotherapy?].

    PubMed

    Supiot, S; Clément-Colmou, K; Paris, F; Corre, I; Chiavassa, S; Delpon, G

    2015-10-01

    Hypofractionated radiotherapy is now more widely prescribed due to improved targeting techniques (intensity modulated radiotherapy, image-guided radiotherapy and stereotactic radiotherapy). Low dose hypofractionated radiotherapy is routinely administered mostly for palliative purposes. High or very high dose hypofractionated irradiation must be delivered according to very strict procedures since every minor deviation can lead to major changes in dose delivery to the tumor volume and organs at risk. Thus, each stage of the processing must be carefully monitored starting from the limitations and the choice of the hypofractionation technique, tumour contouring and dose constraints prescription, planning and finally dose calculation and patient positioning verification. PMID:26321647

  14. Parotid Gland Dose in Intensity-Modulated Radiotherapy for Head and Neck Cancer: Is What You Plan What You Get?

    SciTech Connect

    O'Daniel, Jennifer C.; Garden, Adam S.; Schwartz, David L.; Wang He; Ang, Kian K.; Ahamad, Anesa; Rosenthal, David I.; Morrison, William H.; Asper, Joshua A.; Zhang Lifei; Tung Shihming; Mohan, Radhe; Dong Lei

    2007-11-15

    Purpose: To quantify the differences between planned and delivered parotid gland and target doses, and to assess the benefits of daily bone alignment for head and neck cancer patients treated with intensity-modulated radiotherapy (IMRT). Methods and Materials: Eleven head and neck cancer patients received two CT scans per week with an in-room CT scanner over the course of their radiotherapy. The clinical IMRT plans, designed with 3-mm to 4-mm planning margins, were recalculated on the repeat CT images. The plans were aligned using the actual treatment isocenter marked with radiopaque markers (BB) and bone alignment to the cervical vertebrae to simulate image-guided setup. In-house deformable image registration software was used to map daily dose distributions to the original treatment plan and to calculate a cumulative delivered dose distribution for each patient. Results: Using conventional BB alignment led to increases in the parotid gland mean dose above the planned dose by 5 to 7 Gy in 45% of the patients (median, 3.0 Gy ipsilateral, p = 0.026; median, 1.0 Gy contralateral, p = 0.016). Use of bone alignment led to reductions relative to BB alignment in 91% of patients (median, 2 Gy; range, 0.3-8.3 Gy; 15 of 22 parotids improved). However, the parotid dose from bone alignment was still greater than planned (median, 1.0 Gy, p = 0.007). Neither approach affected tumor dose coverage. Conclusions: With conventional BB alignment, the parotid gland mean dose was significantly increased above the planned mean dose. Using daily bone alignment reduced the parotid dose compared with BB alignment in almost all patients. A 3- to 4-mm planning margin was adequate for tumor dose coverage.

  15. SU-E-J-97: Pretreatment Test and Post-Treatment Evaluation for Iso-NTCP Dose Guided Adapive Radiotherapy (DGART), Experience with Prostate Cancer Patients Treated with Rectal Balloons

    SciTech Connect

    Yu, J; Hardcastle, N; Bender, E; Jeong, K; Tome', M

    2014-06-01

    Purpose: To explore the feasibility of pretreatment test for iso-NTCP DGART and to compare the pretreatment test results with post-treatment evaluations. Methods: NTCP here refers to late rectal wall toxicity only and is calculated with the ring rectal wall DVH. Simulation for one time iso- NTCP DGART starts after half of the total dose was done for 10 patients to investigate if TCP gains could be achieved. Six patients were treated using a 12-fraction 4.3Gy technique and four using 16-fraction 3.63Gy technique. For each of the 12-fraction cases a VMAT plan was generated in Pinnacle3™ using the daily CT obtained prior to the 6th fraction. A pretreatment simulation was performed using only the first 6 daily CTs. The idea is to add the 6 original plan delivered doses with 6 DGART plan delivered doses by deformable dose accumulation (DDA) on each of the first 6 CTs, resulting in 6 rectal wall doses (RWDs) and NTCPs. The 95% confidence interval (95%CI) for the 6 NTCPs were computed.The posttreatment evaluation was done by: a) copy the DGART plan to 6 CTs for fraction 7–12 and calculate the 6 actual DGART delivered fractional doses; b) sum the 6 actual DGART doses with the 6 original plan delivered doses by DDA on each of the 12 CTs resulting in 12 post-treatment RWDs and NTCPs; c) boxplot the 12 post-treatment NTCPs. Results: Target dose gain is 0.76–1.93 Gy. The 95%CI widths of the pretreatment tests NTCPs were 1.1–2.7%. For 5 patients, the planned NTCP fell within the 95%CI. For 4 patients, the planned NTCP was lower than the 95%CI lines. Post-treatment results show that for 7 patients, the upper quartile was within the 95%CI; for 2 patients, the upper quartile were higher than the 95%CI. Conclusion: The pretreatment test yields conservative prediction of the actual delivered NTCP.

  16. Analysis of Electronic Densities and Integrated Doses in Multiform Glioblastomas Stereotactic Radiotherapy

    NASA Astrophysics Data System (ADS)

    Barón-Aznar, C.; Moreno-Jiménez, S.; Celis, M. A.; Lárraga-Gutiérrez, J. M.; Ballesteros-Zebadúa, P.

    2008-08-01

    Integrated dose is the total energy delivered in a radiotherapy target. This physical parameter could be a predictor for complications such as brain edema and radionecrosis after stereotactic radiotherapy treatments for brain tumors. Integrated Dose depends on the tissue density and volume. Using CT patients images from the National Institute of Neurology and Neurosurgery and BrainScansoftware, this work presents the mean density of 21 multiform glioblastomas, comparative results for normal tissue and estimated integrated dose for each case. The relationship between integrated dose and the probability of complications is discussed.

  17. Analysis of Electronic Densities and Integrated Doses in Multiform Glioblastomas Stereotactic Radiotherapy

    SciTech Connect

    Baron-Aznar, C.; Moreno-Jimenez, S.; Celis, M. A.; Ballesteros-Zebadua, P.; Larraga-Gutierrez, J. M.

    2008-08-11

    Integrated dose is the total energy delivered in a radiotherapy target. This physical parameter could be a predictor for complications such as brain edema and radionecrosis after stereotactic radiotherapy treatments for brain tumors. Integrated Dose depends on the tissue density and volume. Using CT patients images from the National Institute of Neurology and Neurosurgery and BrainScan(c) software, this work presents the mean density of 21 multiform glioblastomas, comparative results for normal tissue and estimated integrated dose for each case. The relationship between integrated dose and the probability of complications is discussed.

  18. Temporary organ displacement coupled with image-guided, intensity-modulated radiotherapy for paraspinal tumors

    PubMed Central

    2013-01-01

    Background To investigate the feasibility and dosimetric improvements of a novel technique to temporarily displace critical structures in the pelvis and abdomen from tumor during high-dose radiotherapy. Methods Between 2010 and 2012, 11 patients received high-dose image-guided intensity-modulated radiotherapy with temporary organ displacement (TOD) at our institution. In all cases, imaging revealed tumor abutting critical structures. An all-purpose drainage catheter was introduced between the gross tumor volume (GTV) and critical organs at risk (OAR) and infused with normal saline (NS) containing 5-10% iohexol. Radiation planning was performed with the displaced OARs and positional reproducibility was confirmed with cone-beam CT (CBCT). Patients were treated within 36 hours of catheter placement. Radiation plans were re-optimized using pre-TOD OARs to the same prescription and dosimetrically compared with post-TOD plans. A two-tailed permutation test was performed on each dosimetric measure. Results The bowel/rectum was displaced in six patients and kidney in four patients. One patient was excluded due to poor visualization of the OAR; thus 10 patients were analyzed. A mean of 229 ml (range, 80–1000) of NS 5-10% iohexol infusion resulted in OAR mean displacement of 17.5 mm (range, 7–32). The median dose prescribed was 2400 cGy in one fraction (range, 2100–3000 in 3 fractions). The mean GTV Dmin and PTV Dmin pre- and post-bowel TOD IG-IMRT dosimetry significantly increased from 1473 cGy to 2086 cGy (p=0.015) and 714 cGy to 1214 cGy (p=0.021), respectively. TOD increased mean PTV D95 by 27.14% of prescription (p=0.014) while the PTV D05 decreased by 9.2% (p=0.011). TOD of the bowel resulted in a 39% decrease in mean bowel Dmax (p=0.008) confirmed by CBCT. TOD of the kidney significantly decreased mean kidney dose and Dmax by 25% (0.022). Conclusions TOD was well tolerated, reproducible, and facilitated dose escalation to previously radioresistant tumors

  19. Assessment and Minimization of Contralateral Breast Dose for Conventional and Intensity Modulated Breast Radiotherapy

    SciTech Connect

    Burmeister, Jay Alvarado, Nicole; Way, Sarah; McDermott, Patrick; Bossenberger, Todd; Jaenisch, Harriett; Patel, Rajiv; Washington, Tara

    2008-04-01

    Breast radiotherapy is associated with an increased risk of contralateral breast cancer (CBC) in women under age 45 at the time of treatment. This risk increases with increasing absorbed dose to the contralateral breast. The use of intensity modulated radiotherapy (IMRT) is expected to substantially reduce the dose to the contralateral breast by eliminating scattered radiation from physical beam modifiers. The absorbed dose to the contralateral breast was measured for 5 common radiotherapy techniques, including paired 15 deg. wedges, lateral 30 deg. wedge only, custom-designed physical compensators, aperture based (field-within-field) IMRT with segments chosen by the planner, and inverse planned IMRT with segments chosen by a leaf sequencing algorithm after dose volume histogram (DVH)-based fluence map optimization. Further reduction in contralateral breast dose through the use of lead shielding was also investigated. While shielding was observed to have the most profound impact on surface dose, the radiotherapy technique proved to be most important in determining internal dose. Paired wedges or compensators result in the highest contralateral breast doses (nearly 10% of the prescription dose on the medial surface), while use of IMRT or removal of the medial wedge results in significantly lower doses. Aperture-based IMRT results in the lowest internal doses, primarily due to the decrease in the number of monitor units required and the associated reduction in leakage dose. The use of aperture-based IMRT reduced the average dose to the contralateral breast by greater than 50% in comparison to wedges or compensators. Combined use of IMRT and 1/8-inch-thick lead shielding reduced the dose to the interior and surface of the contralateral breast by roughly 60% and 85%, respectively. This reduction may warrant the use of IMRT for younger patients who have a statistically significant risk of contralateral breast cancer associated with breast radiotherapy.

  20. Radiotherapy of Cervical Cancer.

    PubMed

    Vordermark, Dirk

    2016-01-01

    Curative-intent radical radiotherapy of cervical cancer consists of external-beam radiotherapy, brachytherapy, and concomitant chemotherapy with cisplatin. For each element, new developments aim to improve tumor control rates or treatment tolerance. Intensity-modulated radiotherapy (IMRT) has been shown to reduce gastrointestinal toxicity and can be used to selectively increase the radiotherapy dose. Individualized, image-guided brachytherapy enables better adaptation of high-dose volumes to the tumor extension. Intensification of concomitant or sequential systemic therapy is under evaluation. PMID:27614991

  1. Dose calculation accuracies in whole breast radiotherapy treatment planning: a multi-institutional study.

    PubMed

    Hatanaka, Shogo; Miyabe, Yuki; Tohyama, Naoki; Kumazaki, Yu; Kurooka, Masahiko; Okamoto, Hiroyuki; Tachibana, Hidenobu; Kito, Satoshi; Wakita, Akihisa; Ohotomo, Yuko; Ikagawa, Hiroyuki; Ishikura, Satoshi; Nozaki, Miwako; Kagami, Yoshikazu; Hiraoka, Masahiro; Nishio, Teiji

    2015-07-01

    Our objective in this study was to evaluate the variation in the doses delivered among institutions due to dose calculation inaccuracies in whole breast radiotherapy. We have developed practical procedures for quality assurance (QA) of radiation treatment planning systems. These QA procedures are designed to be performed easily at any institution and to permit comparisons of results across institutions. The dose calculation accuracy was evaluated across seven institutions using various irradiation conditions. In some conditions, there was a >3 % difference between the calculated dose and the measured dose. The dose calculation accuracy differs among institutions because it is dependent on both the dose calculation algorithm and beam modeling. The QA procedures in this study are useful for verifying the accuracy of the dose calculation algorithm and of the beam model before clinical use for whole breast radiotherapy. PMID:25646770

  2. Brain dose-sparing radiotherapy techniques for localized intracranial germinoma: Case report and literature review of modern irradiation.

    PubMed

    Leung, H W C; Chan, A L F; Chang, M B

    2016-05-01

    We examined the effects of intensity-modulated radiation therapy with dose-sparing and avoidance technique on a pediatric patient with localized intracranial germinoma. We also reviewed the literature regarding modern irradiation techniques in relation to late neurocognitive sequelae. A patient with a localized intracranial germinoma in the third ventricle anterior to the pineal gland received a dose-sparing intensity-modulated radiation therapy. The planning was compared to the radiation oncologist's guide of organs at risk and dose constraints for dosimetric analyses. The patient received radiation therapy alone. The total dose was 54Gy delivered in 2.0Gy fractions to the primary tumour and 37Gy in 1.4Gy fractions to whole ventricles using a dose-sculpting plan. Dosimetry analyses showed that dose-sparing intensity-modulated radiation therapy delivered reduced doses to the whole brain, temporal lobes, hippocampi, cochleae, and optic nerves. With a follow-up of 22 months, failure-free survival was 100% for the patient and no adverse events during radiation treatment process. Intensity-modulated radiation therapy with dose sparing and avoidance technique can spare the limbic circuit, central nervous system, and hippocampus for pineal germ cell tumours. This technique reduces the integral dose delivered to the uninvolved normal brain tissues and may reduce late neurocognitive sequelae caused by cranial radiotherapy. PMID:27080575

  3. Image-guided radiotherapy platform using single nodule conditional lung cancer mouse models

    PubMed Central

    Herter-Sprie, Grit S.; Korideck, Houari; Christensen, Camilla L.; Herter, Jan M.; Rhee, Kevin; Berbeco, Ross I.; Bennett, David G.; Akbay, Esra A.; Kozono, David; Mak, Raymond H.; Makrigiorgos, G. Mike; Kimmelman, Alec C.; Wong, Kwok-Kin

    2014-01-01

    Close resemblance of murine and human trials is essential to achieve the best predictive value of animal-based translational cancer research. Kras-driven genetically engineered mouse models of non-small cell lung cancer faithfully predict the response of human lung cancers to systemic chemotherapy. Due to development of multifocal disease, however, these models have not been usable in studies of outcomes following focal radiotherapy (RT). We report the development of a preclinical platform to deliver state-of-the-art image-guided RT in these models. Presence of a single tumour as usually diagnosed in patients is modelled by confined injection of adenoviral Cre recombinase. Furthermore, three-dimensional conformal planning and state-of-the-art image-guided dose delivery are performed as in humans. We evaluate treatment efficacies of two different radiation regimens and find that Kras-driven tumours can temporarily be stabilized upon RT, whereas additional loss of either Lkb1 or p53 renders these lesions less responsive to RT. PMID:25519892

  4. Improvement in toxicity in high risk prostate cancer patients treated with image-guided intensity-modulated radiotherapy compared to 3D conformal radiotherapy without daily image guidance

    PubMed Central

    2014-01-01

    Background Image-guided radiotherapy (IGRT) facilitates the delivery of a very precise radiation dose. In this study we compare the toxicity and biochemical progression-free survival between patients treated with daily image-guided intensity-modulated radiotherapy (IG-IMRT) and 3D conformal radiotherapy (3DCRT) without daily image guidance for high risk prostate cancer (PCa). Methods A total of 503 high risk PCa patients treated with radiotherapy (RT) and endocrine treatment between 2000 and 2010 were retrospectively reviewed. 115 patients were treated with 3DCRT, and 388 patients were treated with IG-IMRT. 3DCRT patients were treated to 76 Gy and without daily image guidance and with 1–2 cm PTV margins. IG-IMRT patients were treated to 78 Gy based on daily image guidance of fiducial markers, and the PTV margins were 5–7 mm. Furthermore, the dose-volume constraints to both the rectum and bladder were changed with the introduction of IG-IMRT. Results The 2-year actuarial likelihood of developing grade > = 2 GI toxicity following RT was 57.3% in 3DCRT patients and 5.8% in IG-IMRT patients (p < 0.001). For GU toxicity the numbers were 41.8% and 29.7%, respectively (p = 0.011). On multivariate analysis, 3DCRT was associated with a significantly increased risk of developing grade > = 2 GI toxicity compared to IG-IMRT (p < 0.001, HR = 11.59 [CI: 6.67-20.14]). 3DCRT was also associated with an increased risk of developing GU toxicity compared to IG-IMRT. The 3-year actuarial biochemical progression-free survival probability was 86.0% for 3DCRT and 90.3% for IG-IMRT (p = 0.386). On multivariate analysis there was no difference in biochemical progression-free survival between 3DCRT and IG-IMRT. Conclusion The difference in toxicity can be attributed to the combination of the IMRT technique with reduced dose to organs-at-risk, daily image guidance and margin reduction. PMID:24495815

  5. Available evidence on re-irradiation with stereotactic ablative radiotherapy following high-dose previous thoracic radiotherapy for lung malignancies.

    PubMed

    De Bari, Berardino; Filippi, Andrea Riccardo; Mazzola, Rosario; Bonomo, Pierluigi; Trovò, Marco; Livi, Lorenzo; Alongi, Filippo

    2015-06-01

    Patients affected with intra-thoracic recurrences of primary or secondary lung malignancies after a first course of definitive radiotherapy have limited therapeutic options, and they are often treated with a palliative intent. Re-irradiation with stereotactic ablative radiotherapy (SABR) represents an appealing approach, due to the optimized dose distribution that allows for high-dose delivery with better sparing of organs at risk. This strategy has the goal of long-term control and even cure. Aim of this review is to report and discuss published data on re-irradiation with SABR in terms of efficacy and toxicity. Results indicate that thoracic re-irradiation may offer satisfactory disease control, however the data on outcome and toxicity are derived from low quality retrospective studies, and results should be cautiously interpreted. As SABR may be associated with serious toxicity, attention should be paid for an accurate patients' selection. PMID:25913714

  6. Inverse Relationship Between Biochemical Outcome and Acute Toxicity After Image-Guided Radiotherapy for Prostate Cancer

    SciTech Connect

    Vesprini, Danny; Catton, Charles; Jacks, Lindsay; Lockwood, Gina; Rosewall, Tara; Bayley, Andrew; Chung, Peter; Gospodarowicz, Mary; Menard, Cynthia; Milosevic, Michael; Nichol, Alan; Skala, Marketa; Warde, Padraig; Bristow, Robert G.

    2012-06-01

    Purpose: Prostate cancer patients exhibit variability in normal tissue reactions and biochemical failure. With the use of image-guided radiotherapy (IGRT), there is a greater likelihood that the differences in normal tissue and tumor response are due to biological rather than physical factors. We tested the hypothesis that prospectively scored acute toxicity is associated with biochemical failure-free rate (BFFR) in prostate cancer patients treated with IGRT. Methods and Materials: We retrospectively analyzed BFFR in 362 patients with localized prostate cancer treated with IGRT. We compared BFFR with prospectively collected Radiation Therapy Oncology Group (RTOG) maximum acute gastrointestinal (GI) and genitourinary (GU) toxicity scores. Median follow-up for all patients was 58.3 months after total radiotherapy doses of 75.6-79.8 Gy. Results: Patients reporting RTOG acute GU or GI toxicity scores of {>=}2 were considered 'sensitive' (n = 141, 39%) and patients reporting scores <2 were considered 'nonsensitive' (n = 221, 61%). When calculating biochemical failure (BF) using the American Society for Therapeutic Radiology and Oncology definition at 5 years, 76% (CI 70-82%) of the 'nonsensitive' patients were failure free, compared with only 53% (CI 43-62%) of the 'sensitive' patients (log-rank test, p < 0.0001). This difference was also observed using the Phoenix definition; 'nonsensitive' 5-year BFFR was 81% (CI 74-86%) vs. 'sensitive' BFFR was 68% (CI 58-76%; log-rank test p = 0.0012). The difference in BF between cohorts remained significant when controlled for radiation dose (75.6 vs. 79.8 Gy), prognostic stratification (T category, prostate-specific antigen, and Gleason score), and prostate volume. Conclusions: This study unexpectedly shows that prostate cancer patients who develop {>=}Grade 2 RTOG acute toxicity during radiotherapy are less likely to remain BFF at 5 years. These results deserve further study and, if validated in other large IGRT cohorts

  7. Estimation of effective imaging dose for kilovoltage intratreatment monitoring of the prostate position during cancer radiotherapy

    NASA Astrophysics Data System (ADS)

    Ng, J. A.; Booth, J.; Poulsen, P.; Kuncic, Z.; Keall, P. J.

    2013-09-01

    Kilovoltage intratreatment monitoring (KIM) is a novel real-time localization modality where the tumor position is continuously measured during intensity modulated radiation therapy (IMRT) or intensity modulated arc therapy (IMAT) by a kilovoltage (kV) x-ray imager. Adding kV imaging during therapy adds radiation dose. The additional effective dose is quantified for prostate radiotherapy and compared to dose from other localization modalities. The software PCXMC 2.0 was used to calculate the effective dose delivered to a phantom as a function of imager angle and field size for a Varian On-Board Imager. The average angular effective dose was calculated for a field size of 6 cm × 6 cm. The average angular effective dose was used in calculations for different treatment scenarios. Treatment scenarios considered were treatment type and fractionation. For all treatment scenarios, (i.e. conventionally fractionated and stereotactic body radiotherapy (SBRT), IMRT and IMAT), the total KIM dose at 1 Hz ranged from 2-10 mSv. This imaging dose is less than the Navotek radioactive implant dose (64 mSv) and a standard SBRT cone beam computed tomography pretreatment scan dose (22 mSv) over an entire treatment regime. KIM delivers an acceptably low effective dose for daily use as a real-time image-guidance method for prostate radiotherapy.

  8. Reconstruction of Organ Dose for External Radiotherapy Patients in Retrospective Epidemiologic Studies

    PubMed Central

    Lee, Choonik; Jung, Jae Won; Pelletier, Christopher; Pyakuryal, Anil; Lamart, Stephanie; Kim, Jongoh; Lee, Choonsik

    2015-01-01

    Organ dose estimation for retrospective epidemiological studies of late effects in radiotherapy patients involves two challenges: radiological images to represent patient anatomy are not usually available for patient cohorts who were treated years ago, and efficient dose reconstruction methods for large-scale patient cohorts are not well established. In the current study, we developed methods to reconstruct organ doses for radiotherapy patients by using a series of computational human phantoms coupled with a commercial treatment planning system (TPS) and a radiotherapy-dedicated Monte Carlo transport code, and performed illustrative dose calculations. First, we developed methods to convert the anatomy and organ contours of the pediatric and adult hybrid computational phantom series to Digital Imaging and Communications in Medicine (DICOM)-image and DICOM-structure files, respectively. The resulting DICOM files were imported to a commercial TPS for simulating radiotherapy and dose calculation for in-field organs. The conversion process was validated by comparing electron densities relative to water and organ volumes between the hybrid phantoms and the DICOM files imported in TPS, which showed agreements within 0.1% and 2%, respectively. Second, we developed a procedure to transfer DICOM-RT files generated from the Eclipse system directly to a Monte Carlo transport code, X-ray Voxel Monte Carlo (XVMC) for more accurate dose calculations. Third, to illustrate the performance of the established methods, we simulated a whole brain treatment for the 10-year-old male phantom and a prostate treatment for the adult male phantom. Radiation doses to selected organs were calculated using the Eclipse and XVMC, and compared to each other. Organ average doses from the two methods matched within 7%, whereas maximum and minimum point doses differed up to 45%. The dosimetry methods and procedures established in this study will be useful for the reconstruction of organ dose to

  9. Reconstruction of organ dose for external radiotherapy patients in retrospective epidemiologic studies.

    PubMed

    Lee, Choonik; Jung, Jae Won; Pelletier, Christopher; Pyakuryal, Anil; Lamart, Stephanie; Kim, Jong Oh; Lee, Choonsik

    2015-03-21

    Organ dose estimation for retrospective epidemiological studies of late effects in radiotherapy patients involves two challenges: radiological images to represent patient anatomy are not usually available for patient cohorts who were treated years ago, and efficient dose reconstruction methods for large-scale patient cohorts are not well established. In the current study, we developed methods to reconstruct organ doses for radiotherapy patients by using a series of computational human phantoms coupled with a commercial treatment planning system (TPS) and a radiotherapy-dedicated Monte Carlo transport code, and performed illustrative dose calculations. First, we developed methods to convert the anatomy and organ contours of the pediatric and adult hybrid computational phantom series to Digital Imaging and Communications in Medicine (DICOM)-image and DICOM-structure files, respectively. The resulting DICOM files were imported to a commercial TPS for simulating radiotherapy and dose calculation for in-field organs. The conversion process was validated by comparing electron densities relative to water and organ volumes between the hybrid phantoms and the DICOM files imported in TPS, which showed agreements within 0.1 and 2%, respectively. Second, we developed a procedure to transfer DICOM-RT files generated from the TPS directly to a Monte Carlo transport code, x-ray Voxel Monte Carlo (XVMC) for more accurate dose calculations. Third, to illustrate the performance of the established methods, we simulated a whole brain treatment for the 10 year-old male phantom and a prostate treatment for the adult male phantom. Radiation doses to selected organs were calculated using the TPS and XVMC, and compared to each other. Organ average doses from the two methods matched within 7%, whereas maximum and minimum point doses differed up to 45%. The dosimetry methods and procedures established in this study will be useful for the reconstruction of organ dose to support

  10. Reconstruction of organ dose for external radiotherapy patients in retrospective epidemiologic studies

    NASA Astrophysics Data System (ADS)

    Lee, Choonik; Jung, Jae Won; Pelletier, Christopher; Pyakuryal, Anil; Lamart, Stephanie; Kim, Jong Oh; Lee, Choonsik

    2015-03-01

    Organ dose estimation for retrospective epidemiological studies of late effects in radiotherapy patients involves two challenges: radiological images to represent patient anatomy are not usually available for patient cohorts who were treated years ago, and efficient dose reconstruction methods for large-scale patient cohorts are not well established. In the current study, we developed methods to reconstruct organ doses for radiotherapy patients by using a series of computational human phantoms coupled with a commercial treatment planning system (TPS) and a radiotherapy-dedicated Monte Carlo transport code, and performed illustrative dose calculations. First, we developed methods to convert the anatomy and organ contours of the pediatric and adult hybrid computational phantom series to Digital Imaging and Communications in Medicine (DICOM)-image and DICOM-structure files, respectively. The resulting DICOM files were imported to a commercial TPS for simulating radiotherapy and dose calculation for in-field organs. The conversion process was validated by comparing electron densities relative to water and organ volumes between the hybrid phantoms and the DICOM files imported in TPS, which showed agreements within 0.1 and 2%, respectively. Second, we developed a procedure to transfer DICOM-RT files generated from the TPS directly to a Monte Carlo transport code, x-ray Voxel Monte Carlo (XVMC) for more accurate dose calculations. Third, to illustrate the performance of the established methods, we simulated a whole brain treatment for the 10 year-old male phantom and a prostate treatment for the adult male phantom. Radiation doses to selected organs were calculated using the TPS and XVMC, and compared to each other. Organ average doses from the two methods matched within 7%, whereas maximum and minimum point doses differed up to 45%. The dosimetry methods and procedures established in this study will be useful for the reconstruction of organ dose to support

  11. Integral test phantom for dosimetric quality assurance of image guided and intensity modulated stereotactic radiotherapy

    SciTech Connect

    Letourneau, Daniel; Keller, Harald; Sharpe, Michael B.; Jaffray, David A.

    2007-05-15

    The objective of this work is to develop a dosimetric phantom quality assurance (QA) of linear accelerators capable of cone-beam CT (CBCT) image guided and intensity-modulated radiotherapy (IG-IMRT). This phantom is to be used in an integral test to quantify in real-time both the performance of the image guidance and the dose delivery systems in terms of dose localization. The prototype IG-IMRT QA phantom consisted of a cylindrical imaging phantom (CatPhan) combined with an array of 11 radiation diodes mounted on a 10 cm diameter disk, oriented perpendicular to the phantom axis. Basic diode response characterization was performed for 6 and 18 MV photons. The diode response was compared to planning system calculations in the open and penumbrae regions of simple and complex beam arrangements. The clinical use of the QA phantom was illustrated in an integral test of an IG-IMRT treatment designed for a clinical spinal radiosurgery case. The sensitivity of the phantom to multileaf collimator (MLC) calibration and setup errors in the clinical setting was assessed by introducing errors in the IMRT plan or by displacing the phantom. The diodes offered good response linearity and long-term reproducibility for both 6 and 18 MV. Axial dosimetry of coplanar beams (in a plane containing the beam axes) was made possible with the nearly isoplanatic response of the diodes over 360 deg. of gantry (usually within {+-}1%). For single beam geometry, errors in phantom placement as small as 0.5 mm could be accurately detected (in gradient {>=}1%/mm). In clinical setting, MLC systematic errors of 1 mm on a single MLC bank introduced in the IMRT plan were easily detectable with the QA phantom. The QA phantom demonstrated also sufficient sensitivity for the detection of setup errors as small as 1 mm for the IMRT delivery. These results demonstrated that the prototype can accurately and efficiently verify the entire IG-IMRT process. This tool, in conjunction with image guidance capabilities

  12. Increasing the Therapeutic Ratio of Stereotactic Ablative Radiotherapy by Individualized Isotoxic Dose Prescription.

    PubMed

    Zindler, Jaap D; Thomas, Charles R; Hahn, Stephen M; Hoffmann, Aswin L; Troost, Esther G C; Lambin, Philippe

    2016-02-01

    To obtain a favorable tradeoff between treatment benefits and morbidity ("therapeutic ratio"), radiotherapy (RT) dose is prescribed according to the tumor volume, with the goal of controlling the disease while respecting normal tissue tolerance levels. We propose a new paradigm for tumor dose prescription in stereotactic ablative radiotherapy (SABR) based on organ-at-risk (OAR) tolerance levels called isotoxic dose prescription (IDP), which is derived from experiences and limitations of conventionally fractionated radiotherapy. With IDP, the radiation dose is prescribed based on the predefined level of normal tissue complication probability of a nearby dose-limiting OAR at a prespecified dose-volume constraint. Simultaneously, the prescribed total tumor dose (TTD) is maximized to the technically highest achievable level in order to increase the local tumor control probability (TCP). IDP is especially relevant for tumors located at eloquent locations or for large tumors in which severe toxicity has been described. IDP will result in a lower RT dose or a treatment scheduled with more fractions if the OAR tolerance level is exceeded, and potential dose escalation occurs when the OAR tolerance level allows it and when it is expected to be beneficial (if TCP < 90%). For patients with small tumors at noneloquent sites, the current SABR dose prescription already results in high rates of local control at low toxicity rates. In this review, the concept of IDP is described in the context of SABR. PMID:26476075

  13. DOSE TO RADIOLOGICAL TECHNOLOGISTS FROM INDUCED RADIONUCLIDES IN CARBON ION RADIOTHERAPY.

    PubMed

    Yonai, S; Spano, V

    2016-09-01

    Radioactive nuclides are induced in irradiation devices and patients during high-energy photon and ion beam radiotherapies. These nuclides potentially become sources of exposure to radiation workers. Radiological technologists (RTs) are often required to enter an irradiation room and approach activated devices and patients. In this study, annual doses to RTs working in a carbon ion radiotherapy facility were estimated based on measurements with the Si-semiconductor personal dosemeter. In addition, the time decay of dose around a patient couch after irradiation was obtained by phantom experiments. The annual Hp(10) values for passive and scanned beams were estimated to be 61 and 2 μSv, respectively, when assuming the number of treatments in 2013. These are much lower than the ICRP recommended dose limit for radiation workers. The time-series data of dose to RTs during their work and the time decay of the dose should be helpful for reducing their dose further. PMID:27179122

  14. Dose response explorer: an integrated open-source tool for exploring and modelling radiotherapy dose volume outcome relationships

    NASA Astrophysics Data System (ADS)

    El Naqa, I.; Suneja, G.; Lindsay, P. E.; Hope, A. J.; Alaly, J. R.; Vicic, M.; Bradley, J. D.; Apte, A.; Deasy, J. O.

    2006-11-01

    Radiotherapy treatment outcome models are a complicated function of treatment, clinical and biological factors. Our objective is to provide clinicians and scientists with an accurate, flexible and user-friendly software tool to explore radiotherapy outcomes data and build statistical tumour control or normal tissue complications models. The software tool, called the dose response explorer system (DREES), is based on Matlab, and uses a named-field structure array data type. DREES/Matlab in combination with another open-source tool (CERR) provides an environment for analysing treatment outcomes. DREES provides many radiotherapy outcome modelling features, including (1) fitting of analytical normal tissue complication probability (NTCP) and tumour control probability (TCP) models, (2) combined modelling of multiple dose-volume variables (e.g., mean dose, max dose, etc) and clinical factors (age, gender, stage, etc) using multi-term regression modelling, (3) manual or automated selection of logistic or actuarial model variables using bootstrap statistical resampling, (4) estimation of uncertainty in model parameters, (5) performance assessment of univariate and multivariate analyses using Spearman's rank correlation and chi-square statistics, boxplots, nomograms, Kaplan-Meier survival plots, and receiver operating characteristics curves, and (6) graphical capabilities to visualize NTCP or TCP prediction versus selected variable models using various plots. DREES provides clinical researchers with a tool customized for radiotherapy outcome modelling. DREES is freely distributed. We expect to continue developing DREES based on user feedback.

  15. Intensity-Modulated Radiotherapy Might Increase Pneumonitis Risk Relative to Three-Dimensional Conformal Radiotherapy in Patients Receiving Combined Chemotherapy and Radiotherapy: A Modeling Study of Dose Dumping

    SciTech Connect

    Vogelius, Ivan S.; Westerly, David C.; Cannon, George M.; Mackie, Thomas R.; Mehta, Minesh P.; Sugie, Chikao; Bentzen, Soren M.

    2011-07-01

    Purpose: To model the possible interaction between cytotoxic chemotherapy and the radiation dose distribution with respect to the risk of radiation pneumonitis. Methods and Materials: A total of 18 non-small-cell lung cancer patients previously treated with helical tomotherapy at the University of Wisconsin were selected for the present modeling study. Three treatment plans were considered: the delivered tomotherapy plans; a three-dimensional conformal radiotherapy (3D-CRT) plan; and a fixed-field intensity-modulated radiotherapy (IMRT) plan. The IMRT and 3D-CRT plans were generated specifically for the present study. The plans were optimized without adjusting for the chemotherapy effect. The effect of chemotherapy was modeled as an independent cell killing process by considering a uniform chemotherapy equivalent radiation dose added to all voxels of the organ at risk. The risk of radiation pneumonitis was estimated for all plans using the Lyman and the critical volume models. Results: For radiotherapy alone, the critical volume model predicts that the two IMRT plans are associated with a lower risk of radiation pneumonitis than the 3D-CRT plan. However, when the chemotherapy equivalent radiation dose exceeds a certain threshold, the radiation pneumonitis risk after IMRT is greater than after 3D-CRT. This threshold dose is in the range estimated from clinical chemoradiotherapy data sets. Conclusions: Cytotoxic chemotherapy might affect the relative merit of competing radiotherapy plans. More work is needed to improve our understanding of the interaction between chemotherapy and the radiation dose distribution in clinical settings.

  16. Dosimetry of dose distributions in radiotherapy of patients with surgical implants

    NASA Astrophysics Data System (ADS)

    Brożyna, Bogusław; Chełmiński, Krzysztof; Bulski, Wojciech; Giżyńska, Marta; Grochowska, Paulina; Walewska, Agnieszka; Zalewska, Marta; Kawecki, Andrzej; Krajewski, Romuald

    2014-11-01

    The investigation was performed in order to evaluate the use of Gafchromic EBT films for measurements of dose distributions created during radiotherapy in tissues surrounding titanium or resorbable implants used for joining and consolidating facial bones. Inhomogeneous dose distributions at implant-tissue interfaces can be the reason of normal tissue complications observed in radiotherapy patients after surgery with implants. The dose measured at a depth of 2.5 cm on contact surfaces, proximal and distal to the beam source, between the titanium implant and the phantom material was 109% and 92% respectively of the reference dose measured in a homogeneous phantom. For the resorbable implants the doses measured on the proximal and the distal contact surfaces were 102% and 101% respectively of the reference dose. The resorbable implants affect the homogeneity of dose distribution at a significantly lesser degree than the titanium implants. Gafchromic EBT films allowed for precise dose distribution measurements at the contact surfaces between tissue equivalent materials and implants. We measured doses at contact surfaces between titanium implants and RW3 phantom. We measured doses at contact surfaces between resorbable implants and RW3 phantom. We compared doses measured on contact surfaces and doses in homogeneous phantom. Doses at contact surfaces between RW3 phantom and titanium were distorted about 8-9%. Doses at RW3 phantom and resorbable implant contact surfaces were distorted about 2%.

  17. Image-driven, model-based 3D abdominal motion estimation for MR-guided radiotherapy

    NASA Astrophysics Data System (ADS)

    Stemkens, Bjorn; Tijssen, Rob H. N.; de Senneville, Baudouin Denis; Lagendijk, Jan J. W.; van den Berg, Cornelis A. T.

    2016-07-01

    Respiratory motion introduces substantial uncertainties in abdominal radiotherapy for which traditionally large margins are used. The MR-Linac will open up the opportunity to acquire high resolution MR images just prior to radiation and during treatment. However, volumetric MRI time series are not able to characterize 3D tumor and organ-at-risk motion with sufficient temporal resolution. In this study we propose a method to estimate 3D deformation vector fields (DVFs) with high spatial and temporal resolution based on fast 2D imaging and a subject-specific motion model based on respiratory correlated MRI. In a pre-beam phase, a retrospectively sorted 4D-MRI is acquired, from which the motion is parameterized using a principal component analysis. This motion model is used in combination with fast 2D cine-MR images, which are acquired during radiation, to generate full field-of-view 3D DVFs with a temporal resolution of 476 ms. The geometrical accuracies of the input data (4D-MRI and 2D multi-slice acquisitions) and the fitting procedure were determined using an MR-compatible motion phantom and found to be 1.0–1.5 mm on average. The framework was tested on seven healthy volunteers for both the pancreas and the kidney. The calculated motion was independently validated using one of the 2D slices, with an average error of 1.45 mm. The calculated 3D DVFs can be used retrospectively for treatment simulations, plan evaluations, or to determine the accumulated dose for both the tumor and organs-at-risk on a subject-specific basis in MR-guided radiotherapy.

  18. Image-driven, model-based 3D abdominal motion estimation for MR-guided radiotherapy.

    PubMed

    Stemkens, Bjorn; Tijssen, Rob H N; de Senneville, Baudouin Denis; Lagendijk, Jan J W; van den Berg, Cornelis A T

    2016-07-21

    Respiratory motion introduces substantial uncertainties in abdominal radiotherapy for which traditionally large margins are used. The MR-Linac will open up the opportunity to acquire high resolution MR images just prior to radiation and during treatment. However, volumetric MRI time series are not able to characterize 3D tumor and organ-at-risk motion with sufficient temporal resolution. In this study we propose a method to estimate 3D deformation vector fields (DVFs) with high spatial and temporal resolution based on fast 2D imaging and a subject-specific motion model based on respiratory correlated MRI. In a pre-beam phase, a retrospectively sorted 4D-MRI is acquired, from which the motion is parameterized using a principal component analysis. This motion model is used in combination with fast 2D cine-MR images, which are acquired during radiation, to generate full field-of-view 3D DVFs with a temporal resolution of 476 ms. The geometrical accuracies of the input data (4D-MRI and 2D multi-slice acquisitions) and the fitting procedure were determined using an MR-compatible motion phantom and found to be 1.0-1.5 mm on average. The framework was tested on seven healthy volunteers for both the pancreas and the kidney. The calculated motion was independently validated using one of the 2D slices, with an average error of 1.45 mm. The calculated 3D DVFs can be used retrospectively for treatment simulations, plan evaluations, or to determine the accumulated dose for both the tumor and organs-at-risk on a subject-specific basis in MR-guided radiotherapy. PMID:27362636

  19. Automatic block-matching registration to improve lung tumor localization during image-guided radiotherapy

    NASA Astrophysics Data System (ADS)

    Robertson, Scott Patrick

    To improve relatively poor outcomes for locally-advanced lung cancer patients, many current efforts are dedicated to minimizing uncertainties in radiotherapy. This enables the isotoxic delivery of escalated tumor doses, leading to better local tumor control. The current dissertation specifically addresses inter-fractional uncertainties resulting from patient setup variability. An automatic block-matching registration (BMR) algorithm is implemented and evaluated for the purpose of directly localizing advanced-stage lung tumors during image-guided radiation therapy. In this algorithm, small image sub-volumes, termed "blocks", are automatically identified on the tumor surface in an initial planning computed tomography (CT) image. Each block is independently and automatically registered to daily images acquired immediately prior to each treatment fraction. To improve the accuracy and robustness of BMR, this algorithm incorporates multi-resolution pyramid registration, regularization with a median filter, and a new multiple-candidate-registrations technique. The result of block-matching is a sparse displacement vector field that models local tissue deformations near the tumor surface. The distribution of displacement vectors is aggregated to obtain the final tumor registration, corresponding to the treatment couch shift for patient setup correction. Compared to existing rigid and deformable registration algorithms, the final BMR algorithm significantly improves the overlap between target volumes from the planning CT and registered daily images. Furthermore, BMR results in the smallest treatment margins for the given study population. However, despite these improvements, large residual target localization errors were noted, indicating that purely rigid couch shifts cannot correct for all sources of inter-fractional variability. Further reductions in treatment uncertainties may require the combination of high-quality target localization and adaptive radiotherapy.

  20. Inter- and Intrafraction Uncertainty in Prostate Bed Image-Guided Radiotherapy

    SciTech Connect

    Huang, Kitty; Palma, David A.; Scott, Danielle; McGregor, Danielle; Gaede, Stewart; Yartsev, Slav; Bauman, Glenn; Louie, Alexander V.; Rodrigues, George

    2012-10-01

    Purpose: The goals of this study were to measure inter- and intrafraction setup error and prostate bed motion (PBM) in patients undergoing post-prostatectomy image-guided radiotherapy (IGRT) and to propose appropriate population-based three-dimensional clinical target volume to planning target volume (CTV-PTV) margins in both non-IGRT and IGRT scenarios. Methods and Materials: In this prospective study, 14 patients underwent adjuvant or salvage radiotherapy to the prostate bed under image guidance using linac-based kilovoltage cone-beam CT (kV-CBCT). Inter- and intrafraction uncertainty/motion was assessed by offline analysis of three consecutive daily kV-CBCT images of each patient: (1) after initial setup to skin marks, (2) after correction for positional error/immediately before radiation treatment, and (3) immediately after treatment. Results: The magnitude of interfraction PBM was 2.1 mm, and intrafraction PBM was 0.4 mm. The maximum inter- and intrafraction prostate bed motion was primarily in the anterior-posterior direction. Margins of at least 3-5 mm with IGRT and 4-7 mm without IGRT (aligning to skin marks) will ensure 95% of the prescribed dose to the clinical target volume in 90% of patients. Conclusions: PBM is a predominant source of intrafraction error compared with setup error and has implications for appropriate PTV margins. Based on inter- and estimated intrafraction motion of the prostate bed using pre- and post-kV-CBCT images, CBCT IGRT to correct for day-to-day variances can potentially reduce CTV-PTV margins by 1-2 mm. CTV-PTV margins for prostate bed treatment in the IGRT and non-IGRT scenarios are proposed; however, in cases with more uncertainty of target delineation and image guidance accuracy, larger margins are recommended.

  1. Determination of subcellular compartment sizes for estimating dose variations in radiotherapy.

    PubMed

    Poole, Christopher M; Ahnesjö, Anders; Enger, Shirin A

    2015-09-01

    The variation in specific energy absorbed to different cell compartments caused by variations in size and chemical composition is poorly investigated in radiotherapy. The aim of this study was to develop an algorithm to derive cell and cell nuclei size distributions from 2D histology samples, and build 3D cellular geometries to provide Monte Carlo (MC)-based dose calculation engines with a morphologically relevant input geometry. Stained and unstained regions of the histology samples are segmented using a Gaussian mixture model, and individual cell nuclei are identified via thresholding. Delaunay triangulation is applied to determine the distribution of distances between the centroids of nearest neighbour cells. A pouring simulation is used to build a 3D virtual tissue sample, with cell radii randomised according to the cell size distribution determined from the histology samples. A slice with the same thickness as the histology sample is cut through the 3D data and characterised in the same way as the measured histology. The comparison between this virtual slice and the measured histology is used to adjust the initial cell size distribution into the pouring simulation. This iterative approach of a pouring simulation with adjustments guided by comparison is continued until an input cell size distribution is found that yields a distribution in the sliced geometry that agrees with the measured histology samples. The thus obtained morphologically realistic 3D cellular geometry can be used as input to MC-based dose calculation programs for studies of dose response due to variations in morphology and size of tumour/healthy tissue cells/nuclei, and extracellular material. PMID:25969521

  2. Low-Dose Palliative Radiotherapy for Cutaneous B- and T-Cell Lymphomas

    SciTech Connect

    Neelis, Karen J. Schimmel, Erik C.; Vermeer, Maarten H.; Senff, Nancy J.; Willemze, Rein; Noordijk, Evert M.

    2009-05-01

    Purpose: To determine the efficacy of low-dose palliative radiotherapy for both low-grade malignant cutaneous B-cell lymphomas (CBCLs) and cutaneous T-cell lymphomas (mycosis fungoides). Methods and Materials: A total of 18 patients with low-grade CBCL (10 primary cutaneous marginal zone B-cell and 8 primary cutaneous follicle center lymphomas) with 44 symptomatic plaques and tumors underwent low-dose (4 Gy in two fractions) local radiotherapy. A total of 31 patients with mycosis fungoides were treated at 82 symptomatic sites, initially with 4 Gy and later with 8 Gy in two fractions. Results: The complete response rate for CBCL lesions was 72%. Of the 44 B-cell lymphoma lesions, 13 were re-treated to the same site after a median of 6.3 months because of persistent (n = 8) or recurrent (n = 5) symptomatic disease. Of the mycosis fungoides patients treated with 4 Gy in two fractions (17 lesions), 70% failed to respond. Increasing the dose to 8 Gy in two fractions yielded a complete response rate of 92% (60 of 65 lesions). The patients in whom low-dose radiotherapy failed were retreated with 20 Gy in eight fractions. Conclusion: Our results have demonstrated that low-dose involved-field radiotherapy induces a high response rate in both CBCL and cutaneous T-cell lymphoma lesions without any toxicity. Therefore, this treatment is now our standard palliative treatment. At progression, it is safe and feasible to apply greater radiation doses.

  3. Specific recommendations for accurate and direct use of PET-CT in PET guided radiotherapy for head and neck sites

    SciTech Connect

    Thomas, C. M. Convery, D. J.; Greener, A. G.; Pike, L. C.; Baker, S.; Woods, E.; Hartill, C. E.

    2014-04-15

    Purpose: To provide specific experience-based guidance and recommendations for centers wishing to develop, validate, and implement an accurate and efficient process for directly using positron emission tomography-computed tomography (PET-CT) for the radiotherapy planning of head and neck cancer patients. Methods: A PET-CT system was modified with hard-top couch, external lasers and radiotherapy immobilization and indexing devices and was subject to a commissioning and quality assurance program. PET-CT imaging protocols were developed specifically for radiotherapy planning and the image quality and pathway tested using phantoms and five patients recruited into an in-house study. Security and accuracy of data transfer was tested throughout the whole data pathway. The patient pathway was fully established and tested ready for implementation in a PET-guided dose-escalation trial for head and neck cancer patients. Results: Couch deflection was greater than for departmental CT simulator machines. An area of high attenuation in the couch generated image artifacts and adjustments were made accordingly. Using newly developed protocols CT image quality was suitable to maintain delineation and treatment accuracy. Upon transfer of data to the treatment planning system a half pixel offset between PET and CT was observed and corrected. By taking this into account, PET to CT alignment accuracy was maintained below 1 mm in all systems in the data pathway. Transfer of structures delineated in the PET fusion software to the radiotherapy treatment planning system was validated. Conclusions: A method to perform direct PET-guided radiotherapy planning was successfully validated and specific recommendations were developed to assist other centers. Of major concern is ensuring that the quality of PET and CT data is appropriate for radiotherapy treatment planning and on-treatment verification. Couch movements can be compromised, bore-size can be a limitation for certain immobilization

  4. Single high-dose vs. fractionated radiotherapy: Effects on plant growth rates

    PubMed Central

    Guedea, Marc; Castel, Antoni; Arnalte, Marc; Mollera, Alex; Muñoz, Victor; Guedea, Ferran

    2013-01-01

    Aim To evaluate the differential effects of fractionated vs. high-dose radiotherapy on plant growth. Background Interest in hypofractionated radiotherapy has increased substantially in recent years as tumours (especially of the lung, prostate, and liver) can be irradiated with ever greater accuracy due to technological improvements. The effects of low-dose ionizing radiation on plant growth have been studied extensively, yet few studies have investigated the effect of high-dose, hypofractionated radiotherapy on plant growth development. Materials and methods A total of 150 plants from the genus Capsicum annuum were randomized to receive fractionated radiotherapy (5 doses of 10 Gy each), single high-dose (SHD) radiotherapy (single 50 Gy dose), or no radiotherapy (control group). Irradiation was delivered via linear accelerator and all samples were followed daily for 26 days to assess and compare daily growth. Results On day 26, plants in the control, fractionated, and SHD groups had grown to a mean height of 7.55 cm, 4.32 cm, and 2.94 cm, respectively. These differences in overall growth were highly significant (P = 0.005). The SHD group showed the least amount of growth. Conclusions SHD effectively stunts plant growth and development. Despite the evident differences between plant and animal cells, ionizing radiation is believed to work in a similar manner in all biological cells. These findings highlight the need to continue investigating the use of hypofractionated schemes in humans to improve cancer treatment outcomes. PMID:24416565

  5. Skin dose mapping for fluoroscopically guided interventions

    PubMed Central

    Johnson, Perry B.; Borrego, David; Balter, Stephen; Johnson, Kevin; Siragusa, Daniel; Bolch, Wesley E.

    2011-01-01

    Purpose: To introduce a new skin dose mapping software system for interventional fluoroscopy dose assessment and to analyze the benefits and limitations of patient-phantom matching. Methods: In this study, a new software system was developed for visualizing patient skin dose during interventional fluoroscopy procedures. The system works by translating the reference point air kerma to the location of the patient’s skin, which is represented by a computational model. In order to orient the model with the x-ray source, geometric parameters found within the radiation dose structured report (RDSR) are used along with a limited number of in-clinic measurements. The output of the system is a visual indication of skin dose mapped onto an anthropomorphic model at a resolution of 5 mm. In order to determine if patient-dependent and patient-sculpted models increase accuracy, peak skin dose was calculated for each of 26 patient-specific models and compared with doses calculated using an elliptical stylized model, a reference hybrid model, a matched patient-dependent model and one patient-sculpted model. Results were analyzed in terms of a percent difference using the doses calculated using the patient-specific model as the true standard. Results: Anthropometric matching, including the use of both patient-dependent and patient-sculpted phantoms, was shown most beneficial for left lateral and anterior–posterior projections. In these cases, the percent difference using a reference model was between 8 and 20%, using a patient-dependent model between 7 and 15%, and using a patient-sculpted model between 3 and 7%. Under the table tube configurations produced errors less than 5% in most situations due to the flattening affects of the table and pad, and the fact that table height is the main determination of source-to-skin distance for these configurations. In addition to these results, several skin dose maps were produced and a prototype display system was placed on the in

  6. Skin dose mapping for fluoroscopically guided interventions

    SciTech Connect

    Johnson, Perry B.; Borrego, David; Balter, Stephen; Johnson, Kevin; Siragusa, Daniel; Bolch, Wesley E.

    2011-10-15

    Purpose: To introduce a new skin dose mapping software system for interventional fluoroscopy dose assessment and to analyze the benefits and limitations of patient-phantom matching. Methods: In this study, a new software system was developed for visualizing patient skin dose during interventional fluoroscopy procedures. The system works by translating the reference point air kerma to the location of the patient's skin, which is represented by a computational model. In order to orient the model with the x-ray source, geometric parameters found within the radiation dose structured report (RDSR) are used along with a limited number of in-clinic measurements. The output of the system is a visual indication of skin dose mapped onto an anthropomorphic model at a resolution of 5 mm. In order to determine if patient-dependent and patient-sculpted models increase accuracy, peak skin dose was calculated for each of 26 patient-specific models and compared with doses calculated using an elliptical stylized model, a reference hybrid model, a matched patient-dependent model and one patient-sculpted model. Results were analyzed in terms of a percent difference using the doses calculated using the patient-specific model as the true standard. Results: Anthropometric matching, including the use of both patient-dependent and patient-sculpted phantoms, was shown most beneficial for left lateral and anterior-posterior projections. In these cases, the percent difference using a reference model was between 8 and 20%, using a patient-dependent model between 7 and 15%, and using a patient-sculpted model between 3 and 7%. Under the table tube configurations produced errors less than 5% in most situations due to the flattening affects of the table and pad, and the fact that table height is the main determination of source-to-skin distance for these configurations. In addition to these results, several skin dose maps were produced and a prototype display system was placed on the in

  7. Dose-Volume Comparison of Proton Radiotherapy and Stereotactic Body Radiotherapy for Non-Small-Cell Lung Cancer

    SciTech Connect

    Kadoya, Noriyuki; Obata, Yasunori; Kato, Takahiro; Kagiya, Masaru; Nakamura, Tatsuya; Tomoda, Takuya; Takada, Akinori; Takayama, Kanako; Fuwa, Nobukazu

    2011-03-15

    Purpose: This study designed photon and proton treatment plans for patients treated with hypofractionated proton radiotherapy (PT) at the Southern Tohoku Proton Therapy Center (STPTC). We then calculated dosimetric parameters and compared results with simulated treatment plans for stereotactic body radiotherapy (SBRT), using dose--volume histograms to clearly explain differences in dose distributions between PT and SBRT. Methods and Materials: Twenty-one patients with stage I non-small-cell lung cancer (stage IA, n = 15 patients; stage IB, n = 6 patients) were studied. All tumors were located in the peripheral lung, and total dose was 66 Gray equivalents (GyE) (6.6 GyE/fraction). For treatment planning, beam incidence for proton beam technique was restricted to two to three directions for PT, and seven or eight noncoplanar beams were manually selected for SBRT to achieve optimal planning target volume (PTV) coverage and minimal dose to organs at risk. Results: Regarding lung tissues, mean dose, V5, V10, V13, V15, and V20 values were 4.6 Gy, 13.2%, 11.4%, 10.6%, 10.1%, and 9.1%, respectively, for PT, whereas those values were 7.8 Gy, 32.0%, 21.8%, 17.4%, 15.3%, and 11.4%, respectively, for SBRT with a prescribed dose of 66 Gy. Pearson product moment correlation coefficients between PTV and dose--volume parameters of V5, V10, V15, and V20 were 0.45, 0.52, 0.58, and 0.63, respectively, for PT, compared to 0.52, 0.45, 0.71, and 0.74, respectively, for SBRT. Conclusions: Correlations between dose--volume parameters of the lung and PTV were observed and may indicate that PT is more advantageous than SBRT when treating a tumor with a relatively large PTV or several tumors.

  8. Deformable Dose Reconstruction to Optimize the Planning and Delivery of Liver Cancer Radiotherapy

    NASA Astrophysics Data System (ADS)

    Velec, Michael

    The precise delivery of radiation to liver cancer patients results in improved control with higher tumor doses and minimized normal tissues doses. A margin of normal tissue around the tumor requires irradiation however to account for treatment delivery uncertainties. Daily image-guidance allows targeting of the liver, a surrogate for the tumor, to reduce geometric errors. However poor direct tumor visualization, anatomical deformation and breathing motion introduce uncertainties between the planned dose, calculated on a single pre-treatment computed tomography image, and the dose that is delivered. A novel deformable image registration algorithm based on tissue biomechanics was applied to previous liver cancer patients to track targets and surrounding organs during radiotherapy. Modeling these daily anatomic variations permitted dose accumulation, thereby improving calculations of the delivered doses. The accuracy of the algorithm to track dose was validated using imaging from a deformable, 3-dimensional dosimeter able to optically track absorbed dose. Reconstructing the delivered dose revealed that 70% of patients had substantial deviations from the initial planned dose. An alternative image-guidance technique using respiratory-correlated imaging was simulated, which reduced both the residual tumor targeting errors and the magnitude of the delivered dose deviations. A planning and delivery strategy for liver radiotherapy was then developed that minimizes the impact of breathing motion, and applied a margin to account for the impact of liver deformation during treatment. This margin is 38% smaller on average than the margin used clinically, and permitted an average dose-escalation to liver tumors of 9% for the same risk of toxicity. Simulating the delivered dose with deformable dose reconstruction demonstrated the plans with smaller margins were robust as 90% of patients' tumors received the intended dose. This strategy can be readily implemented with widely

  9. Investigation of Linac-Based Image-Guided Hypofractionated Prostate Radiotherapy

    SciTech Connect

    Pawlicki, Todd . E-mail: tpaw@stanford.edu; Kim, Gwe-Ya; Hsu, Annie; Cotrutz, Cristian; Boyer, Arthur L.; Xing Lei; King, Christopher R.; Luxton, Gary

    2007-07-01

    A hypofractionation treatment protocol for prostate cancer was initiated in our department in December 2003. The treatment regimen consists of a total dose of 36.25 Gy delivered at 7.25 Gy per fraction over 10 days. We discuss the rationale for such a prostate hypofractionation protocol and the need for frequent prostate imaging during treatment. The CyberKnife (Accuray Inc., Sunnyvale, CA), a linear accelerator mounted on a robotic arm, is currently being used as the radiation delivery device for this protocol, due to its incorporation of near real-time kV imaging of the prostate via 3 gold fiducial seeds. Recently introduced conventional linac kV imaging with intensity modulated planning and delivery may add a new option for these hypofractionated treatments. The purpose of this work is to investigate the use of intensity modulated radiotherapy (IMRT) and the Varian Trilogy Accelerator with on-board kV imaging (Varian Medical Systems Inc., Palo Alto, CA) for treatment of our hypofractionated prostate patients. The dose-volume histograms and dose statistics of 2 patients previously treated on the CyberKnife were compared to 7-field IMRT plans. A process of acquiring images to observe intrafraction prostate motion was achieved in an average time of about 1 minute and 40 seconds, and IMRT beam delivery takes about 40 seconds per field. A complete 7-field IMRT plan can therefore be imaged and delivered in 10 to 17 minutes. The Varian Trilogy Accelerator with on-board imaging and IMRT is well suited for image-guided hypofractionated prostate treatments. During this study, we have also uncovered opportunities for improvement of the on-board imaging hardware/software implementation that would further enhance performance in this regard.

  10. Biologically Effective Dose-Response Relationship for Breast Cancer Treated by Conservative Surgery and Postoperative Radiotherapy

    SciTech Connect

    Plataniotis, George A. Dale, Roger G.

    2009-10-01

    Purpose: To find a biologically effective dose (BED) response for adjuvant breast radiotherapy (RT) for initial-stage breast cancer. Methods and Materials: Results of randomized trials of RT vs. non-RT were reviewed and the tumor control probability (TCP) after RT was calculated for each of them. Using the linear-quadratic formula and Poisson statistics of cell-kill, the average initial number of clonogens per tumor before RT and the average tumor cell radiosensitivity (alpha-value) were calculated. An {alpha}/{beta} ratio of 4 Gy was assumed for these calculations. Results: A linear regression equation linking BED to TCP was derived: -ln[-ln(TCP)] = -ln(No) + {alpha}{sup *} BED = -4.08 + 0.07 * BED, suggesting a rather low radiosensitivity of breast cancer cells (alpha = 0.07 Gy{sup -1}), which probably reflects population heterogeneity. From the linear relationship a sigmoid BED-response curve was constructed. Conclusion: For BED values higher than about 90 Gy{sub 4} the radiation-induced TCP is essentially maximizing at 90-100%. The relationship presented here could be an approximate guide in the design and reporting of clinical trials of adjuvant breast RT.

  11. Radiotherapy.

    PubMed

    Adamietz, Irenaus A

    2010-01-01

    The intrathoracic growth of the tumor causes several severe symptoms as cough, dyspnea, chest pain, hemoptysis, hoarseness, anorexia/nausea, and dysphagia. In patients with manifest or threatening symptoms radiotherapy (RT) as an effective measure should be implemented into the management concept. Palliative RT radiotherapy prefers short hypofractionated schemas (e.g. 10 x 3 Gy, 4 x 5 Gy, 2 x 8 Gy, 1 x 10 Gy). Careful radiation planning supports the precision of palliative RT and reduces significantly the complication rate. A good response and prolonged palliation effects (6-12 months) can be achieved in many cases. However, the minimum biologically equivalent dose should not be less than 35 Gy. RT produces a good outcome in all types of metastases of lung carcinoma. In emergencies like VCSS or spinal cord compression RT should be initiated immediately. The selection of the optimal therapy for locally advanced lung carcinoma with malignant airway obstruction is difficult. Both brachytherapy and percutaneous irradiation are effective, however published results including local a sum of response, functionality and life quality demonstrates more benefit by percutaneous RT. Due to different physical properties of these two methods the combination of brachytherapy and external beam irradiation may be advantageous. PMID:19955803

  12. [Postoperative radiotherapy for non-small cell lung cancer: Efficacy, target volume, dose].

    PubMed

    Dupic, G; Bellière-Calandry, A

    2016-04-01

    The rate of local failure of stage IIIA-N2 non-small cell lung cancer is 20 to 40%, even if they are managed with surgery and adjuvant chemotherapy. Postoperative radiotherapy improves local control, but its benefit on global survival remains to be demonstrated. Considered for many years as an adjuvant treatment option for pN2 cancers, it continues nevertheless to be deemed too toxic. What is the current status of postoperative radiotherapy? The Lung Adjuvant Radiotherapy Trial (Lung ART) phase III trial should give us a definitive, objective response on global survival, but inclusion of patients is difficult. The results are consequently delayed. The aim of this review is to show all the results about efficacy and tolerance of postoperative radiotherapy and to define the target volume and dose to prescribe. PMID:26996789

  13. Threshold dose for peripheral neuropathy following intraoperative radiotherapy (IORT) in a large animal model

    SciTech Connect

    Kinsella, T.J.; DeLuca, A.M.; Barnes, M.; Anderson, W.; Terrill, R.; Sindelar, W.F. )

    1991-04-01

    Radiation injury to peripheral nerve is a dose-limiting toxicity in the clinical application of intraoperative radiotherapy, particularly for pelvic and retroperitoneal tumors. Intraoperative radiotherapy-related peripheral neuropathy in humans receiving doses of 20-25 Gy is manifested as a mixed motor-sensory deficit beginning 6-9 months following treatment. In a previous experimental study of intraoperative radiotherapy-related neuropathy of the lumbro-sacral plexus, an approximate inverse linear relationship was reported between the intraoperative dose (20-75 Gy range) and the time to onset of hind limb paresis (1-12 mos following intraoperative radiotherapy). The principal histological lesion in irradiated nerve was loss of large nerve fibers and perineural fibrosis without significant vascular injury. Similar histological changes in irradiated nerves were found in humans. To assess peripheral nerve injury to lower doses of intraoperative radiotherapy in this same large animal model, groups of four adult American Foxhounds received doses of 10, 15, or 20 Gy to the right lumbro-sacral plexus and sciatic nerve using 9 MeV electrons. The left lumbro-sacral plexus and sciatic nerve were excluded from the intraoperative field to allow each animal to serve as its own control. Following treatment, a complete neurological exam, electromyogram, and nerve conduction studies were performed monthly for 1 year. Monthly neurological exams were performed in years 2 and 3 whereas electromyogram and nerve conduction studies were performed every 3 months during this follow-up period. With follow-up of greater than or equal to 42 months, no dog receiving 10 or 15 Gy IORT shows any clinical or laboratory evidence of peripheral nerve injury. However, all four dogs receiving 20 Gy developed right hind limb paresis at 8, 9, 9, and 12 mos following intraoperative radiotherapy.

  14. Image-guided radiotherapy and motion management in lung cancer

    PubMed Central

    2015-01-01

    In this review, image guidance and motion management in radiotherapy for lung cancer is discussed. Motion characteristics of lung tumours and image guidance techniques to obtain motion information are elaborated. Possibilities for management of image guidance and motion in the various steps of the treatment chain are explained, including imaging techniques and beam delivery techniques. Clinical studies using different motion management techniques are reviewed, and finally future directions for image guidance and motion management are outlined. PMID:25955231

  15. High-Dose Conformal Radiotherapy for Patients With Stage III Non-Small-Cell Lung Carcinoma

    SciTech Connect

    Nakayama, Hidetsugu; Satoh, Hiroaki; Kurishima, Koichi; Ishikawa, Hiroichi; Tokuuye, Koichi

    2010-11-01

    Purpose: To determine the effectiveness of high-dose conformal radiotherapy to the involved field for patients with Stage III non-small-cell lung cancer (NSCLC). Methods and Materials: Between May 1999 and April 2006, a total of 100 consecutive patients with inoperable Stage IIIA or IIIB NSCLC with a performance score of 0 to 2 and treatment by radical radiotherapy combined with chemotherapy were included. Up to August 2002, 33 patients underwent conventional radiotherapy of 56 Gy to 66 Gy using anteroposterior opposite ports to the primary tumor and elective lymph nodes (conventional group). After September 2002, the remaining 67 patients underwent high-dose radiotherapy of 66 Gy to 84 Gy to the involved volume with three-dimensional (3-D) conformal radiotherapy (conformal group). Results: The median survival was 13.2 months (95% confidence interval [CI], 7.5-18.5 months) in the conventional group and 17.3 months (95% CI, 10.7- 24.0 months) in the conformal group. The overall survival at 3 years were 9.1% (95% CI, -0.7-18.9%) in the conventional group and 31.0% (95% CI, 18.9-43.1%) in the conformal group; the conformal group had a significantly better overall survival (p < 0.05). The radiotherapy method (hazard ratio = 0.55, p < 0.05) and performance status (hazard ratio = 1.48, p < 0.05) were shown to be statistically significant independent prognostic factors. Conclusions: Based on the practical experience reported here, 3-D conformal radiotherapy allowed dose escalation without excessive toxicity, and may improve overall survival rates for patients with Stage III NSCLC.

  16. Effect of beam arrangement on oral cavity dose in external beam radiotherapy of nasopharyngeal carcinoma

    SciTech Connect

    Wu, Vincent W.C.; Yang Zhining; Zhang Wuzhe; Wu Lili; Lin Zhixiong

    2012-07-01

    This study compared the oral cavity dose between the routine 7-beam intensity-modulated radiotherapy (IMRT) beam arrangement and 2 other 7-beam IMRT with the conventional radiotherapy beam arrangements in the treatment of nasopharyngeal carcinoma (NPC). Ten NPC patients treated by the 7-beam routine IMRT technique (IMRT-7R) between April 2009 and June 2009 were recruited. Using the same computed tomography data, target information, and dose constraints for all the contoured structures, 2 IMRT plans with alternative beam arrangements (IMRT-7M and IMRT-7P) by avoiding the anterior facial beam and 1 conventional radiotherapy plan (CONRT) were computed using the Pinnacle treatment planning system. Dose-volume histograms were generated for the planning target volumes (PTVs) and oral cavity from which the dose parameters and the conformity index of the PTV were recorded for dosimetric comparisons among the plans with different beam arrangements. The dose distributions to the PTVs were similar among the 3 IMRT beam arrangements, whereas the differences were significant between IMRT-7R and CONRT plans. For the oral cavity dose, the 3 IMRT beam arrangements did not show significant difference. Compared with IMRT-7R, CONRT plan showed a significantly lower mean dose, V30 and V-40, whereas the V-60 was significantly higher. The 2 suggested alternative beam arrangements did not significantly reduce the oral cavity dose. The impact of varying the beam angles in IMRT of NPC did not give noticeable effect on the target and oral cavity. Compared with IMRT, the 2-D conventional radiotherapy irradiated a greater high-dose volume in the oral cavity.

  17. Pain and Mean Absorbed Dose to the Pubic Bone After Radiotherapy Among Gynecological Cancer Survivors

    SciTech Connect

    Waldenstroem, Ann-Charlotte; Olsson, Caroline; Wilderaeng, Ulrica; Dunberger, Gail; Lind, Helena; Al-Abany, Massoud; Palm, Asa; Avall-Lundqvist, Elisabeth; Johansson, Karl-Axel; Steineck, Gunnar

    2011-07-15

    Purpose: To analyze the relationship between mean absorbed dose to the pubic bone after pelvic radiotherapy for gynecological cancer and occurrence of pubic bone pain among long-term survivors. Methods and Materials: In an unselected, population-based study, we identified 823 long-term gynecological cancer survivors treated with pelvic radiotherapy during 1991-2003. For comparison, we used a non-radiation-treated control population of 478 matched women from the Swedish Population Register. Pain, intensity of pain, and functional impairment due to pain in the pubic bone were assessed with a study-specific postal questionnaire. Results: We analyzed data from 650 survivors (participation rate 79%) with median follow-up of 6.3 years (range, 2.3-15.0 years) along with 344 control women (participation rate, 72 %). Ten percent of the survivors were treated with radiotherapy; ninety percent with surgery plus radiotherapy. Brachytherapy was added in 81%. Complete treatment records were recovered for 538/650 survivors, with dose distribution data including dose-volume histograms over the pubic bone. Pubic bone pain was reported by 73 survivors (11%); 59/517 (11%) had been exposed to mean absorbed external beam doses <52.5 Gy to the pubic bone and 5/12 (42%) to mean absorbed external beam doses {>=}52.5 Gy. Thirty-three survivors reported pain affecting sleep, a 13-fold increased prevalence compared with control women. Forty-nine survivors reported functional impairment measured as pain walking indoors, a 10-fold increased prevalence. Conclusions: Mean absorbed external beam dose above 52.5 Gy to the pubic bone increases the occurrence of pain in the pubic bone and may affect daily life of long-term survivors treated with radiotherapy for gynecological cancer.

  18. Consideration of the radiation dose delivered away from the treatment field to patients in radiotherapy

    PubMed Central

    Taylor, Michael L.; Kron, Tomas

    2011-01-01

    Radiation delivery to cancer patients for radiotherapy is invariably accompanied by unwanted radiation to other parts of the patient’s body. Traditionally, considerable effort has been made to calculate and measure the radiation dose to the target as well as to nearby critical structures. Only recently has attention been focused also on the relatively low doses that exist far from the primary radiation beams. In several clinical scenarios, such doses have been associated with cardiac toxicity as well as an increased risk of secondary cancer induction. Out-of-field dose is a result of leakage and scatter and generally difficult to predict accurately. The present review aims to present existing data, from measurements and calculations, and discuss its implications for radiotherapy. PMID:21731221

  19. Dose profile measurements during respiratory-gated lung stereotactic radiotherapy: A phantom study

    NASA Astrophysics Data System (ADS)

    Jong, W. L.; Wong, J. H. D.; Ng, K. H.; Ung, N. M.

    2016-03-01

    During stereotactic body radiotherapy, high radiation dose (∼60 Gy) is delivered to the tumour in small fractionation regime. In this study, the dosimetric characteristics were studied using radiochromic film during respiratory-gated and non-gated lung stereotactic body radiotherapy (SBRT). Specifically, the effect of respiratory cycle and amplitude, as well as gating window on the dosimetry were studied. In this study, the dose profiles along the irradiated area were measured. The dose profiles for respiratory-gated radiation delivery with different respiratory or tumour motion amplitudes, gating windows and respiratory time per cycle were in agreement with static radiation delivery. The respiratory gating system was able to deliver the radiation dose accurately (±1.05 mm) in the longitudinal direction. Although the treatment time for respiratory-gated SBRT was prolonged, this approach can potentially reduce the margin for internal tumour volume without compromising the tumour coverage. In addition, the normal tissue sparing effect can be improved.

  20. A strategy to objectively evaluate the necessity of correcting detected target deviations in image guided radiotherapy

    SciTech Connect

    Yue, Ning J.; Kim, Sung; Jabbour, Salma; Narra, Venkat; Haffty, Bruce G.

    2007-11-15

    Image guided radiotherapy technologies are being increasingly utilized in the treatment of various cancers. These technologies have enhanced the ability to detect temporal and spatial deviations of the target volume relative to planned radiation beams. Correcting these detected deviations may, in principle, improve the accuracy of dose delivery to the target. However, in many situations, a clinical decision has to be made as to whether it is necessary to correct some of the deviations since the relevant dosimetric impact may or may not be significant, and the corresponding corrective action may be either impractical or time consuming. Ideally this decision should be based on objective and reproducible criteria rather than subjective judgment. In this study, a strategy is proposed for the objective evaluation of the necessity of deviation correction during the treatment verification process. At the treatment stage, without any alteration from the planned beams, the treatment beams should provide the desired dose coverage to the geometric volume identical to the planning target volume (PTV). Given this fact, the planned dose distribution and PTV geometry were used to compute the dose coverage and PTV enclosure of the clinical target volume (CTV) that was detected from imaging during the treatment setup verification. The spatial differences between the detected CTV and the planning CTV are essentially the target deviations. The extent of the PTV enclosure of the detected CTV as well as its dose coverage were used as criteria to evaluate the necessity of correcting any of the target deviations. This strategy, in principle, should be applicable to any type of target deviations, including both target deformable and positional changes and should be independent of how the deviations are detected. The proposed strategy was used on two clinical prostate cancer cases. In both cases, gold markers were implanted inside the prostate for the purpose of treatment setup

  1. Effect of Breathing Motion on Radiotherapy Dose Accumulation in the Abdomen Using Deformable Registration

    SciTech Connect

    Velec, Michael; Moseley, Joanne L.; Eccles, Cynthia L.; Craig, Tim; Sharpe, Michael B.; Dawson, Laura A.; Brock, Kristy K.

    2011-05-01

    Purpose: To investigate the effect of breathing motion and dose accumulation on the planned radiotherapy dose to liver tumors and normal tissues using deformable image registration. Methods and Materials: Twenty-one free-breathing stereotactic liver cancer radiotherapy patients, planned on static exhale computed tomography (CT) for 27-60 Gy in six fractions, were included. A biomechanical model-based deformable image registration algorithm retrospectively deformed each exhale CT to inhale CT. This deformation map was combined with exhale and inhale dose grids from the treatment planning system to accumulate dose over the breathing cycle. Accumulation was also investigated using a simple rigid liver-to-liver registration. Changes to tumor and normal tissue dose were quantified. Results: Relative to static plans, mean dose change (range) after deformable dose accumulation (as % of prescription dose) was -1 (-14 to 8) to minimum tumor, -4 (-15 to 0) to maximum bowel, -4 (-25 to 1) to maximum duodenum, 2 (-1 to 9) to maximum esophagus, -2 (-13 to 4) to maximum stomach, 0 (-3 to 4) to mean liver, and -1 (-5 to 1) and -2 (-7 to 1) to mean left and right kidneys. Compared to deformable registration, rigid modeling had changes up to 8% to minimum tumor and 7% to maximum normal tissues. Conclusion: Deformable registration and dose accumulation revealed potentially significant dose changes to either a tumor or normal tissue in the majority of cases as a result of breathing motion. These changes may not be accurately accounted for with rigid motion.

  2. Measurement of dose given by Co-60 in radiotherapy with TLD-500

    NASA Astrophysics Data System (ADS)

    Tanır, Güneş; Cengiz, Ferhat; Hicabi Bölükdemir, M.

    2012-04-01

    The uses of dosimeters based on optically stimulated luminescence technique have become widespread in clinical applications. In the present study, the dose values given by Cobalt-60 radiotherapy machine were measured with optically stimulated luminescence (OSL) technique using TLD-500 and compared with those of commonly used ionization chamber dosimeter system. The percentage depth dose (DD%) values and graphs were formed. OSL system with TLD-500 can be reliably used as medical and personal dosimeter.

  3. Evaluation of Organs at Risk’s Dose in External Radiotherapy of Brain Tumors

    PubMed Central

    Nazemi-Gelyan, Hamideh; Hasanzadeh, Hadi; Makhdumi, Yasha; Abdollahi, Sara; Akbari, Fatemeh; Varshoee-Tabrizi, Fatemeh; Almasrou, Hamzeh; Nikoofar, Alireza; Rezaei-Tavirani, Mostafa

    2015-01-01

    Background Radiotherapy plays an important role in the management of most malignant and many benign primary central nervous system (CNS) tumors. Radiotherapy affects both tumor cells and uninvolved normal cells; so, it is important to estimate absorbed dose to organs at risk in this kind of treatment. The aim of this study was to determine the absorbed dose to chiasma, lens, optic nerve, retina, parotid, thyroid and submandibular gland in frontal lobe brain tumors radiotherapy based on treatment planning system (TPS) calculation and direct measurement on the phantom. Methods A head and neck phantom was constructed using natural human bone and combination of paraffin wax and Sodium Chloride (NaCl) as tissue-equivalent material. Six cylinders were made of phantom material which had cavities to insert Thermoluminescent Dosimeters (TLDs) at several depths in order to measure absorbed dose to chiasma, lens, optic nerve, retina, parotid, thyroid and submandibular gland. Three routine conventional plans associated with tumors of this region and a new purposed technique were performed on the phantom and dose distribution and absorbed dose to critical organs were compared using treatment planning system (TPS) calculation and direct measurement on the phantom. Results Absorbed doses were measured with calibrated TLDs and are expressed in centigray (cGy). In all techniques absorbed dose to all organs except the lenses were at their tolerance dose levels and in the new purposed technique, absorbed dose to chiasma was significantly reduced. Conclusion Our findings showed differences in the range of 1-5% in all techniques between TPS calculation and direct measurements for all organs except submandibular glands and thyroid. Because submandibular glands and thyroid are far from primary radiation field, TLD reading in these regions although small but differs from TPS calculation which shows very smaller doses. This might be due to scattered radiation which is not well considered

  4. Cardiac Dose From Tangential Breast Cancer Radiotherapy in the Year 2006

    SciTech Connect

    Taylor, Carolyn W. Povall, Julie M.; McGale, Paul; Nisbet, Andrew; Dodwell, David; Smith, Jonathan T.; Darby, Sarah C.

    2008-10-01

    Purpose: To quantify the radiation doses received by the heart and coronary arteries from contemporary tangential breast or chest wall radiotherapy. Methods and Materials: Fifty consecutive patients with left-sided breast cancer and 5 consecutive patients with right-sided breast cancer treated at a large United Kingdom radiotherapy center during the year 2006 were selected. All patients were irradiated with 6- or 8-MV tangential beams to the breast or chest wall. For each dose plan, dose-volume histograms for the heart and left anterior descending (LAD) coronary artery were calculated. For 5 of the left-sided and all 5 right-sided patients, dose-volume histograms for the right and circumflex coronary arteries were also calculated. Detailed spatial assessment of dose to the LAD coronary artery was performed for 3 left-sided patients. Results: For the 50 patients given left-sided irradiation, the average mean (SD) dose was 2.3 (0.7) Gy to the heart and 7.6 (4.5) Gy to the LAD coronary artery, with the distal LAD receiving the highest doses. The right and circumflex coronary arteries received approximately 2 Gy mean dose. Part of the heart received >20 Gy in 22 left-sided patients (44%). For the 5 patients given right-sided irradiation, average mean doses to all cardiac structures were in the range 1.2 to 2 Gy. Conclusions: Heart dose from left-tangential radiotherapy has decreased considerably over the past 40 years, but part of the heart still receives >20 Gy for approximately half of left-sided patients. Cardiac dose for right-sided patients was generally from scattered irradiation alone.

  5. The feasibility of using a conventional flexible RF coil for an online MR-guided radiotherapy treatment

    NASA Astrophysics Data System (ADS)

    Hoogcarspel, Stan J.; Crijns, Sjoerd P. M.; Lagendijk, Jan J. W.; van Vulpen, Marco; Raaymakers, Bas W.

    2013-03-01

    The purpose of this paper is to evaluate the impact of a flexible radiofrequency coil on the treatment delivery of an online MR-guided radiotherapy treatment. For this study, we used a Synergy MR body coil (Philips, Best) in combination with the current MRL prototype of the UMC Utrecht. The compatibility of the coil is evaluated in two steps. First, we evaluated the dosimetric impact of the MR coil on both a simple and a complex irradiation strategy for treating spinal bone metastases. This tumor site will likely be chosen for the first in-man treatments with the UMC Utrecht MRL system. Second, we investigated the impact of the treatment beam on the MRI performance of the body coil. In case a single posterior-anterior rectangular field was applied, dose to the target volume was underestimated up to 2.2% as a result of beam attenuation in the MR coil. This underestimation however, decreased to 1% when a stereotactic treatment strategy was employed. The presence of the MR coil in or near the distal site of the treatment beam decreased the exit dose when a magnetic field was present. The MRI performance of the coil was unaffected as the result of the radiation. It is feasible to use the Synergy MR body coil for an online MR-guided radiotherapy treatment without any modification to the coil or attenuation correction methods in the planning stage. The effect of the MRI coil on the dose delivery is minimal and there is no effect of the treatment beam on the SNR of the acquired MRI data.

  6. An assessment of PTV margin based on actual accumulated dose for prostate cancer radiotherapy

    PubMed Central

    Wen, Ning; Kumarasiri, Akila; Nurushev, Teamour; Burmeister, Jay; Xing, Lei; Liu, Dezhi; Glide-Hurst, Carri; Kim, Jinkoo; Zhong, Hualiang; Movsas, Benjamin; Chetty, Indrin J

    2014-01-01

    The purpose of this work is to present the results of a margin reduction study involving dosimetric and radiobiologic assessment of cumulative dose distributions, computed using an image guided adaptive radiotherapy based framework. Eight prostate cancer patients, treated with 7–9, 6 MV, intensity modulated radiation therapy (IMRT) fields, were included in this study. The workflow consists of cone beam CT (CBCT) based localization, deformable image registration of the CBCT to simulation CT image datasets (SIMCT), dose reconstruction and dose accumulation on the SIM-CT, and plan evaluation using radiobiological models. For each patient, three IMRT plans were generated with different margins applied to the CTV. The PTV margin for the original plan was 10 mm and 6 mm at the prostate/anterior rectal wall interface (10/6 mm) and was reduced to: (a) 5/3 mm, and (b) 3 mm uniformly. The average percent reductions in predicted tumor control probability (TCP) in the accumulated (actual) plans in comparison to the original plans over eight patients were 0.4%, 0.7% and 11.0% with 10/6 mm, 5/3 mm and 3 mm uniform margin respectively. The mean increase in predicted normal tissue complication probability (NTCP) for grades 2/3 rectal bleeding for the actual plans in comparison to the static plans with margins of 10/6, 5/3 and 3 mm uniformly was 3.5%, 2.8% and 2.4% respectively. For the actual dose distributions, predicted NTCP for late rectal bleeding was reduced by 3.6% on average when the margin was reduced from 10/6 mm to 5/3 mm, and further reduced by 1.0% on average when the margin was reduced to 3 mm. The average reduction in complication free tumor control probability (P+) in the actual plans in comparison to the original plans with margins of 10/6, 5/3 and 3 mm was 3.7%, 2.4% and 13.6% correspondingly. The significant reduction of TCP and P+ in the actual plan with 3 mm margin came from one outlier, where individualizing patient treatment plans through margin adaptation

  7. An assessment of PTV margin based on actual accumulated dose for prostate cancer radiotherapy

    NASA Astrophysics Data System (ADS)

    Wen, Ning; Kumarasiri, Akila; Nurushev, Teamour; Burmeister, Jay; Xing, Lei; Liu, Dezhi; Glide-Hurst, Carri; Kim, Jinkoo; Zhong, Hualiang; Movsas, Benjamin; Chetty, Indrin J.

    2013-11-01

    The purpose of this work is to present the results of a margin reduction study involving dosimetric and radiobiologic assessment of cumulative dose distributions, computed using an image guided adaptive radiotherapy based framework. Eight prostate cancer patients, treated with 7-9, 6 MV, intensity modulated radiation therapy (IMRT) fields, were included in this study. The workflow consists of cone beam CT (CBCT) based localization, deformable image registration of the CBCT to simulation CT image datasets (SIM-CT), dose reconstruction and dose accumulation on the SIM-CT, and plan evaluation using radiobiological models. For each patient, three IMRT plans were generated with different margins applied to the CTV. The PTV margin for the original plan was 10 mm and 6 mm at the prostate/anterior rectal wall interface (10/6 mm) and was reduced to: (a) 5/3 mm, and (b) 3 mm uniformly. The average percent reductions in predicted tumor control probability (TCP) in the accumulated (actual) plans in comparison to the original plans over eight patients were 0.4%, 0.7% and 11.0% with 10/6 mm, 5/3 mm and 3 mm uniform margin respectively. The mean increase in predicted normal tissue complication probability (NTCP) for grades 2/3 rectal bleeding for the actual plans in comparison to the static plans with margins of 10/6, 5/3 and 3 mm uniformly was 3.5%, 2.8% and 2.4% respectively. For the actual dose distributions, predicted NTCP for late rectal bleeding was reduced by 3.6% on average when the margin was reduced from 10/6 mm to 5/3 mm, and further reduced by 1.0% on average when the margin was reduced to 3 mm. The average reduction in complication free tumor control probability (P+) in the actual plans in comparison to the original plans with margins of 10/6, 5/3 and 3 mm was 3.7%, 2.4% and 13.6% correspondingly. The significant reduction of TCP and P+ in the actual plan with 3 mm margin came from one outlier, where individualizing patient treatment plans through margin adaptation

  8. Dose Imaging Detectors for Radiotherapy Based on Gas Electron Multipliers

    PubMed Central

    Klyachko, A.V.; Friesel, D.L.; Kline, C.; Liechty, J.; Nichiporov, D.F.; Solberg, K.A.

    2010-01-01

    New techniques in charged particle therapy and widespread use of modern dynamic beam delivery systems demand new beam monitoring devices as well as accurate 2D dosimetry systems to verify the delivered dose distribution. We are developing dose imaging detectors based on gas electron multipliers (GEM) with the goal of improving dose measurement linearity, position and timing resolution, and to ultimately allow pre-treatment verification of dose distributions and dose delivery monitoring employing scanning beam technology. A prototype 10×10 cm2 double-GEM detector has been tested in the 205 MeV proton beam using electronic and optical readout modes. Preliminary results with electronic cross-strip readout demonstrate fast response and single-pixel (4 mm) position resolution. In optical readout mode, the line spread function of the detector was found to have σ=0.7 mm. In both readout modes, the detector response was linear up to dose rates of 50 Gy/min, with adequate representation of the Bragg peak in depth-dose profile measurements. PMID:21528010

  9. Potential Applications of Imaging and Image-Guided Radiotherapy for Brain Metastases and Glioblastoma to Improve Patient Quality of Life

    PubMed Central

    Nguyen, Nam P.; Nguyen, Mai L.; Vock, Jacqueline; Lemanski, Claire; Kerr, Christine; Vinh-Hung, Vincent; Chi, Alexander; Khan, Rihan; Woods, William; Altdorfer, Gabor; D’Andrea, Mark; Karlsson, Ulf; Hamilton, Russ; Ampil, Fred

    2013-01-01

    Treatment of glioblastoma multiforme (GBM) and brain metastasis remains a challenge because of the poor survival and the potential for brain damage following radiation. Despite concurrent chemotherapy and radiation dose escalation, local recurrence remains the predominant pattern of failure in GBM most likely secondary to repopulation of cancer stem cells. Even though radiotherapy is highly effective for local control of radio-resistant tumors such as melanoma and renal cell cancer, systemic disease progression is the cause of death in most patients with brain metastasis. Preservation of quality of life (QOL) of cancer survivors is the main issue for patients with brain metastasis. Image-guided radiotherapy (IGRT) by virtue of precise radiation dose delivery may reduce treatment time of patients with GBM without excessive toxicity and potentially improve neurocognitive function with preservation of local control in patients with brain metastasis. Future prospective trials for primary brain tumors or brain metastasis should include IGRT to assess its efficacy to improve patient QOL. PMID:24312897

  10. Primary Cardiac Angiosarcoma Treated With Positron Emission Tomography/Magnetic Resonance Imaging-Guided Adaptive Radiotherapy.

    PubMed

    Elsayad, Khaled; Lehrich, Philipp; Yppaerilae-Wolters, Heidi; Dieckmann, Chantal; Kriz, Jan; Haverkamp, Uwe; Eich, Hans Theodor

    2016-06-01

    Radiotherapy (RT) for inoperable patients with primary cardiac sarcomas or residual tumor is often limited by the sensitivity of the heart and lung to radiation injury. We describe a novel treatment modality with adaptive radiotherapy (ART) using tumor volume tracking in a 37-year-old woman who presented with unresectable primary cardiac angiosarcoma. The patient was treated using positron emission tomography/magnetic resonance imaging-guided ART with 55.8 Gy concomitant with paclitaxel chemotherapy. In conclusion, the treatment was well tolerated, and a significant tumor volume reduction of ∼ 57% was achieved during radiotherapy, suggesting the effectiveness and tolerability of ART in combination with paclitaxel-based chemotherapy. PMID:26514752

  11. SU-E-T-238: Monte Carlo Estimation of Cerenkov Dose for Photo-Dynamic Radiotherapy

    SciTech Connect

    Chibani, O; Price, R; Ma, C; Eldib, A; Mora, G

    2014-06-01

    Purpose: Estimation of Cerenkov dose from high-energy megavoltage photon and electron beams in tissue and its impact on the radiosensitization using Protoporphyrine IX (PpIX) for tumor targeting enhancement in radiotherapy. Methods: The GEPTS Monte Carlo code is used to generate dose distributions from 18MV Varian photon beam and generic high-energy (45-MV) photon and (45-MeV) electron beams in a voxel-based tissueequivalent phantom. In addition to calculating the ionization dose, the code scores Cerenkov energy released in the wavelength range 375–425 nm corresponding to the pick of the PpIX absorption spectrum (Fig. 1) using the Frank-Tamm formula. Results: The simulations shows that the produced Cerenkov dose suitable for activating PpIX is 4000 to 5500 times lower than the overall radiation dose for all considered beams (18MV, 45 MV and 45 MeV). These results were contradictory to the recent experimental studies by Axelsson et al. (Med. Phys. 38 (2011) p 4127), where Cerenkov dose was reported to be only two orders of magnitude lower than the radiation dose. Note that our simulation results can be corroborated by a simple model where the Frank and Tamm formula is applied for electrons with 2 MeV/cm stopping power generating Cerenkov photons in the 375–425 nm range and assuming these photons have less than 1mm penetration in tissue. Conclusion: The Cerenkov dose generated by high-energy photon and electron beams may produce minimal clinical effect in comparison with the photon fluence (or dose) commonly used for photo-dynamic therapy. At the present time, it is unclear whether Cerenkov radiation is a significant contributor to the recently observed tumor regression for patients receiving radiotherapy and PpIX versus patients receiving radiotherapy only. The ongoing study will include animal experimentation and investigation of dose rate effects on PpIX response.

  12. Radiotherapy Dose Perturbation of Esophageal Stents Examined in an Experimental Model

    SciTech Connect

    Atwood, Todd F.; Hsu, Annie; Ogara, Maydeen M.; Luba, Daniel G.; Tamler, Bradley J.; DiSario, James A.; Maxim, Peter G.

    2012-04-01

    Purpose: To investigate the radiotherapy dose perturbations caused by esophageal stents in patients undergoing external beam treatments for esophageal cancer. Methods and Materials: Four esophageal stents were examined (three metallic stents: WallFlex, Ultraflex, and Alveolus; one nonmetallic stent with limited radiopaque markers for visualization: Polyflex). All experiments were performed in a liquid water phantom with a custom acrylic stent holder. Radiochromic film was used to measure the dose distributions adjacent to the stents at locations proximal and distal to the radiation source. The stents were placed in an air-filled cavity to simulate the esophagus. Treatment plans were created and delivered for photon energies of 6 and 15 MV, and data analysis was performed on uniform regions of interest, according to the size and geometric placement of the films, to quantify the dose perturbations. Results: The three metallic stents produced the largest dose perturbations with distinct patterns of 'hot' spots (increased dose) measured proximal to the radiation source (up to 15.4%) and both 'cold' (decreased dose) and hot spots measured distal to the radiation source (range, -6.1%-5.8%). The polymeric Polyflex stent produced similar dose perturbations when the radiopaque markers were examined (range, -7.6%-15.4%). However, when the radiopaque markers were excluded from the analysis, the Polyflex stent produced significantly smaller dose perturbations, with maximum hot spots of 7.3% and cold spots of -3.2%. Conclusions: The dose perturbations caused by esophageal stents during the treatment of esophageal cancer using external beam radiotherapy should be understood. These perturbations will result in hot and cold spots in the esophageal mucosa, with varying magnitudes depending on the stent. The nonmetallic Polyflex stent appears to be the most suitable for patients undergoing radiotherapy, but further studies are necessary to determine the clinical significance of the

  13. Functional Image-Guided Radiotherapy Planning in Respiratory-Gated Intensity-Modulated Radiotherapy for Lung Cancer Patients With Chronic Obstructive Pulmonary Disease

    SciTech Connect

    Kimura, Tomoki; Nishibuchi, Ikuno; Murakami, Yuji; Kenjo, Masahiro; Kaneyasu, Yuko; Nagata, Yasushi

    2012-03-15

    Purpose: To investigate the incorporation of functional lung image-derived low attenuation area (LAA) based on four-dimensional computed tomography (4D-CT) into respiratory-gated intensity-modulated radiotherapy (IMRT) or volumetric modulated arc therapy (VMAT) in treatment planning for lung cancer patients with chronic obstructive pulmonary disease (COPD). Methods and Materials: Eight lung cancer patients with COPD were the subjects of this study. LAA was generated from 4D-CT data sets according to CT values of less than than -860 Hounsfield units (HU) as a threshold. The functional lung image was defined as the area where LAA was excluded from the image of the total lung. Two respiratory-gated radiotherapy plans (70 Gy/35 fractions) were designed and compared in each patient as follows: Plan A was an anatomical IMRT or VMAT plan based on the total lung; Plan F was a functional IMRT or VMAT plan based on the functional lung. Dosimetric parameters (percentage of total lung volume irradiated with {>=}20 Gy [V20], and mean dose of total lung [MLD]) of the two plans were compared. Results: V20 was lower in Plan F than in Plan A (mean 1.5%, p = 0.025 in IMRT, mean 1.6%, p = 0.044 in VMAT) achieved by a reduction in MLD (mean 0.23 Gy, p = 0.083 in IMRT, mean 0.5 Gy, p = 0.042 in VMAT). No differences were noted in target volume coverage and organ-at-risk doses. Conclusions: Functional IGRT planning based on LAA in respiratory-guided IMRT or VMAT appears to be effective in preserving a functional lung in lung cancer patients with COPD.

  14. Effect of the bone heterogeneity on the dose prescription in orthovoltage radiotherapy: A Monte Carlo study

    PubMed Central

    Chow, James C.L.; Grigorov, Grigor N.

    2011-01-01

    Background In orthovoltage radiotherapy, since the dose prescription at the patient's surface is based on the absolute dose calibration using water phantom, deviation of delivered dose is found as the heterogeneity such as bone present under the patient's surface. Aim This study investigated the dosimetric impact due to the bone heterogeneity on the surface dose in orthovoltage radiotherapy. Materials and methods A 220 kVp photon beam with field size of 5 cm diameter, produced by a Gulmay D3225 orthovoltage X-ray machine was modeled by the BEAMnrc. Phantom containing water (thickness = 1–5 mm) on top of a bone (thickness = 1 cm) was irradiated by the 220 kVp photon beam. Percentage depth dose (PDD), surface dose and photon energy spectrum were determined using Monte Carlo simulations (the BEAMnrc code). Results PDD results showed that the maximum bone dose was about 210% higher than the surface dose in the phantoms with different thicknesses of water. Surface dose was found to be increased in the range of 2.5–3.7%, when the distance between the phantom surface and bone was increased in the range of 1–5 mm. The increase of surface dose was found not to follow the increase of water thickness, and the maximum increase of surface dose was found at the thickness of water equal to 3 mm. Conclusions For the accepted total orthovoltage radiation treatment uncertainty of 5%, a neglected consideration of the bone heterogeneity during the dose prescription in the sites of forehead, chest wall and kneecap with soft tissue thickness = 1–5 mm would cause more than two times of the bone dose, and contribute an uncertainty of about 2.5–3.7% to the total uncertainty in the dose delivery. PMID:24376995

  15. EPID-guided 3D dose verification of lung SBRT

    SciTech Connect

    Aristophanous, M.; Rottmann, J.; Court, L. E.; Berbeco, R. I.

    2011-01-15

    Purpose: To investigate the feasibility of utilizing tumor tracks from electronic portal imaging device (EPID) images taken during treatment to verify the delivered dose. Methods: The proposed method is based on a computation of the delivered fluence by utilizing the planned fluence and the tumor motion track for each field. A phantom study was designed to assess the feasibility of the method. The CIRS dynamic thorax phantom was utilized with a realistic soft resin tumor, modeled after a real patient tumor. The dose calculated with the proposed method was compared to direct measurements taken with 15 metal oxide semiconductor field effect transistors (MOSFETs) inserted in small fissures made in the tumor model. The phantom was irradiated with the tumor static and moved with different range of motions and setup errors. EPID images were recorded throughout all deliveries and the tumor model was tracked post-treatment with in-house developed software. The planned fluence for each field was convolved with the tumor motion tracks to obtain the delivered fluence. Utilizing the delivered fluence from each field, the delivered dose was calculated. The estimated delivered dose was compared to the dose directly measured with the MOSFETs. The feasibility of the proposed method was also demonstrated on a real lung cancer patient, treated with stereotactic body radiotherapy. Results: The calculation of delivered dose with the delivered fluence method was in good agreement with the MOSFET measurements, with average differences ranging from 0.8% to 8.3% depending on the proximity of a dose gradient. For the patient treatment, the planned and delivered dose volume histograms were compared and verified the overall good coverage of the target volume. Conclusions: The delivered fluence method was applied successfully on phantom and clinical data and its accuracy was evaluated. Verifying each treatment fraction may enable correction strategies that can be applied during the course of

  16. PET/CT-guided Interventions: Personnel Radiation Dose

    SciTech Connect

    Ryan, E. Ronan Thornton, Raymond; Sofocleous, Constantinos T.; Erinjeri, Joseph P.; Hsu, Meier; Quinn, Brian; Dauer, Lawrence T.; Solomon, Stephen B.

    2013-08-01

    PurposeTo quantify radiation exposure to the primary operator and staff during PET/CT-guided interventional procedures.MethodsIn this prospective study, 12 patients underwent PET/CT-guided interventions over a 6 month period. Radiation exposure was measured for the primary operator, the radiology technologist, and the nurse anesthetist by means of optically stimulated luminescence dosimeters. Radiation exposure was correlated with the procedure time and the use of in-room image guidance (CT fluoroscopy or ultrasound).ResultsThe median effective dose was 0.02 (range 0-0.13) mSv for the primary operator, 0.01 (range 0-0.05) mSv for the nurse anesthetist, and 0.02 (range 0-0.05) mSv for the radiology technologist. The median extremity dose equivalent for the operator was 0.05 (range 0-0.62) mSv. Radiation exposure correlated with procedure duration and with the use of in-room image guidance. The median operator effective dose for the procedure was 0.015 mSv when conventional biopsy mode CT was used, compared to 0.06 mSv for in-room image guidance, although this did not achieve statistical significance as a result of the small sample size (p = 0.06).ConclusionThe operator dose from PET/CT-guided procedures is not significantly different than typical doses from fluoroscopically guided procedures. The major determinant of radiation exposure to the operator from PET/CT-guided interventional procedures is time spent in close proximity to the patient.

  17. Dose to the intracranial arteries in stereotactic and intensity-modulated radiotherapy for skull base tumors

    SciTech Connect

    Nieder, Carsten . E-mail: cnied@hotmail.com; Grosu, Anca L.; Stark, Sybille; Wiedenmann, Nicole; Busch, Raymonde; Kneschaurek, Peter; Molls, Michael

    2006-03-15

    Purpose: To examine retrospectively the maximum dose to the large skull base/intracranial arteries in fractionated stereotactic radiotherapy (FSRT) and intensity-modulated radiotherapy (IMRT), because of the potential risk of perfusion disturbances. Methods and Materials: Overall, 56 patients with tumors adjacent to at least one major artery were analyzed. Our strategy was to perform FSRT with these criteria: 1.8 Gy per fraction, planning target volume (PTV) enclosed by the 95% isodose, maximum dose 107%. Dose limits were applied to established organs at risk, but not the vessels. If FSRT planning failed to meet any of these criteria, IMRT was planned with the same objectives. Results: In 31 patients (median PTV, 23 cm{sup 3}), the FSRT plan fulfilled all criteria. No artery received a dose {>=}105%. Twenty-five patients (median PTV, 39 cm{sup 3}) needed IMRT planning. In 11 of 25 patients (median PTV, 85 cm{sup 3}), no plan satisfying all our criteria could be calculated. Only in this group, moderately increased maximum vessel doses were observed (106-110%, n = 7, median PTV, 121 cm{sup 3}). The median PTV dose gradient was 29% (significantly different from the 14 patients with satisfactory IMRT plans). Three of the four patients in this group had paranasal sinus tumors. Conclusion: The doses to the major arteries should be calculated in IMRT planning for critical tumor locations if a dose gradient >13% within the PTV can not be avoided because the PTV is large or includes air cavities.

  18. Characterization of Fricke-gel layers for absolute dose measurements in radiotherapy

    SciTech Connect

    Gambarini, G.; Carrara, M.; Rrushi, B.; Guilizzoni, R.; Borroni, M.; Tomatis, S.; Pirola, L.; Battistoni, G.

    2011-07-01

    Fricke-gel layer dosimeters (FGLDs) have shown promising features for attaining absolute measurements of the spatial distribution of the absorbed dose in radiotherapy. Good precision of results (within 3%) is achieved by means of calibration of each single dosimeter before measurement. The calibration is performed irradiating the dosimeter at a uniform and precisely known dose, in order to get a calibration matrix that must be used, with pixel-to-pixel manipulation, to obtain the dose image. A study of the trend in time of dosimeter response after one or more exposures was carried out and calibration protocols were suitably established and verified. (authors)

  19. Determination of effective doses in image-guided radiation therapy system

    NASA Astrophysics Data System (ADS)

    Pyone, Y. Y.; Suriyapee, S.; Sanghangthum, T.; Oonsiri, S.; Tawonwong, T.

    2016-03-01

    The organ and effective doses in image-guided radiotherapy system are determined in this study. For 2D imaging, incident air kerma (Ki) was measured by 6cc ionization chamber with Accu-Pro dosimeter. The entrance surface air kerma (ESAK) was calculated by multiplying Ki with backscatter factor. The effective dose was calculated by multiplying ESAK with conversion coefficient. For 3D imaging, computed tomography/cone-beam dose index (CTDI/CBDI) measurements were performed by using 100mm pencil ionization chamber with Accu-Pro dosimeter. The dose index in air and in CTDI phantom from planning CT and cone- beam CT were measured. Then, effective dose was calculated by ImPACT software. The effective doses from 2D conventional simulator for anteroposterior and lateral projections were 01 and 0.02mSv for head, 0.15 and 0.16mSv for thorax, 0.22 and 0.21mSv for pelvis, respectively. The effective doses from 3D, planning CT and CBCT, were 3.3 and 0.1mSv for head, 13 and 2.4mSv for thorax and 7.2 and 4.9mSv for pelvis, respectively. Based on 30 fractions of treatment course, total effective dose (3D CT, 2D setup verification and 6 times CBCT) of head, thorax and pelvis were 3.93, 27.71 and 37.03mSv, respectively. Therefore, IGRT should be administered with significant parameters to reduce the dose.

  20. Evaluation of different fiducial markers for image-guided radiotherapy and particle therapy.

    PubMed

    Habermehl, Daniel; Henkner, Katrin; Ecker, Swantje; Jäkel, Oliver; Debus, Jürgen; Combs, Stephanie E

    2013-07-01

    Modern radiotherapy (RT) techniques are widely used in the irradiation of moving organs. A crucial step in ensuring the correct position of a target structure directly before or during treatment is daily image guidance by computed tomography (CT) or X-ray radiography (image-guided radiotherapy, IGRT). Therefore, combinations of modern irradiation devices and imaging, such as on-board imaging (OBI) with X-rays, or in-room CT such as the tomotherapy system, have been developed. Moreover, combinations of linear accelerators and in-room CT-scanners have been designed. IGRT is of special interest in hypofractionated and radiosurgical treatments where high single doses are applied in the proximity of critical organs at risk. Radiographically visible markers in or in close proximity to the target structure may help to reproduce the position during RT and could therefore be used as external surrogates for motion monitoring. Criteria sought for fiducial markers are (i) visibility in the radiologic modalities involved in radiotherapeutic treatment planning and image guidance, such as CT and kilovoltage (kV) OBI), (ii) low production of imaging artifacts, and (iii) low perturbation of the therapeutic dose to the target volume. Photon interaction with interstitial markers has been shown to be not as important as in particle therapy, where interaction of the particle beam, especially with metal markers, can have a significant impact on treatment. This applies especially with a scanned ion beam. Recently we commenced patient recruitment at our institution within the PROMETHEUS trial, which evaluates a hypofractionation regime, starting with 4 x 10 Gy (RBE), for patients with hepatocellular carcinoma. The aim of this work is, therefore, to evaluate potential implantable fiducial markers for enabling precise patient and thus organ positioning in scanned ion beams. To transfer existing knowledge of marker application from photon to particle therapy, we used a range of commercially

  1. An automatic dose verification system for adaptive radiotherapy for helical tomotherapy

    NASA Astrophysics Data System (ADS)

    Mo, Xiaohu; Chen, Mingli; Parnell, Donald; Olivera, Gustavo; Galmarini, Daniel; Lu, Weiguo

    2014-03-01

    Purpose: During a typical 5-7 week treatment of external beam radiotherapy, there are potential differences between planned patient's anatomy and positioning, such as patient weight loss, or treatment setup. The discrepancies between planned and delivered doses resulting from these differences could be significant, especially in IMRT where dose distributions tightly conforms to target volumes while avoiding organs-at-risk. We developed an automatic system to monitor delivered dose using daily imaging. Methods: For each treatment, a merged image is generated by registering the daily pre-treatment setup image and planning CT using treatment position information extracted from the Tomotherapy archive. The treatment dose is then computed on this merged image using our in-house convolution-superposition based dose calculator implemented on GPU. The deformation field between merged and planning CT is computed using the Morphon algorithm. The planning structures and treatment doses are subsequently warped for analysis and dose accumulation. All results are saved in DICOM format with private tags and organized in a database. Due to the overwhelming amount of information generated, a customizable tolerance system is used to flag potential treatment errors or significant anatomical changes. A web-based system and a DICOM-RT viewer were developed for reporting and reviewing the results. Results: More than 30 patients were analysed retrospectively. Our in-house dose calculator passed 97% gamma test evaluated with 2% dose difference and 2mm distance-to-agreement compared with Tomotherapy calculated dose, which is considered sufficient for adaptive radiotherapy purposes. Evaluation of the deformable registration through visual inspection showed acceptable and consistent results, except for cases with large or unrealistic deformation. Our automatic flagging system was able to catch significant patient setup errors or anatomical changes. Conclusions: We developed an automatic dose

  2. Normal tissue complication probability (NTCP) modelling using spatial dose metrics and machine learning methods for severe acute oral mucositis resulting from head and neck radiotherapy

    PubMed Central

    Dean, Jamie A; Wong, Kee H; Welsh, Liam C; Jones, Ann-Britt; Schick, Ulrike; Newbold, Kate L; Bhide, Shreerang A; Harrington, Kevin J; Nutting, Christopher M; Gulliford, Sarah L

    2016-01-01

    Background and Purpose Severe acute mucositis commonly results from head and neck (chemo)radiotherapy. A predictive model of mucositis could guide clinical decision-making and inform treatment planning. We aimed to generate such a model using spatial dose metrics and machine learning. Material and Methods Predictive models of severe acute mucositis were generated using radiotherapy dose (dose-volume and spatial dose metrics) and clinical data. Penalised logistic regression, support vector classification and random forest classification (RFC) models were generated and compared. Internal validation was performed (with 100-iteration cross-validation), using multiple metrics, including area under the receiver operating characteristic curve (AUC) and calibration slope, to assess performance. Associations between covariates and severe mucositis were explored using the models. Results The dose-volume-based models (standard) performed equally to those incorporating spatial information. Discrimination was similar between models, but the RFCstandard had the best calibration. The mean AUC and calibration slope for this model were 0.71 (s.d.=0.09) and 3.9 (s.d.=2.2), respectively. The volumes of oral cavity receiving intermediate and high doses were associated with severe mucositis. Conclusions The RFCstandard model performance is modest-to-good, but should be improved, and requires external validation. Reducing the volumes of oral cavity receiving intermediate and high doses may reduce mucositis incidence. PMID:27240717

  3. Efficacy of low-dose radiotherapy in painful gonarthritis: experiences from a retrospective East German bicenter study

    PubMed Central

    2013-01-01

    Purpose To evaluate the efficacy of low-dose radiotherapy in painful gonarthritis. Methods We assessed the medical records of 1037 patients with painful gonarthritis who had undergone low-dose radiotherapy between 1981 and 2008. The subjective patient perception of the response to irradiation as graded immediately or up to two months after the completion of a radiotherapy series was evaluated and correlated with age, gender, radiological grading and the duration of symptoms before radiotherapy. Moreover, we performed a mail survey to obtain additional long-term follow-up information and received one hundred and six evaluable questionnaires. Results We assessed 1659 series of radiotherapy in 1037 patients. In 79.3% of the cases the patients experienced a slight, marked or complete pain relief immediately or up to two months after the completion of radiotherapy. Gender, age and the duration of pain before radiotherapy did not have a significant influence on the response to irradiation. In contrast, severe signs of osteoarthritis were associated with more effective pain relief. In more than 50% of the patients who reported a positive response to irradiation a sustained period of symptomatic improvement was observed. Conclusions Our results confirm that low-dose radiotherapy is an effective treatment for painful osteoarthritis of the knee. In contrast to an earlier retrospective study, severe signs of osteoarthritis constituted a positive prognostic factor for the response to irradiation. A randomized trial is urgently required to compare radiotherapy with other treatment modalities. PMID:23369282

  4. Development of an alanine dosimetry system for radiation dose measurements in the radiotherapy range

    NASA Astrophysics Data System (ADS)

    Gago-Arias, A.; González-Castaño, D. M.; Gómez, F.; Peteiro, E.; Lodeiro, C.; Pardo-Montero, J.

    2015-08-01

    Alanine/ESR systems provide an interesting alternative to standard dosimetry systems like solid state or gas ionization chambers for dosimetry in radiotherapy. This is primarily due to the negligible energy dependence, high stability, and the possibility of using small pellets that are especially suitable for the dosimetry of small fields. In order to obtain acceptable dose uncertainties in the radiotherapy dose range, the setup, operational parameters and quantification methods need to be carefully investigated and optimized. In this work we present the development of an alanine/ESR dosimetry system, traced to the secondary standard laboratory of absorbed dose to water at the Radiation Physics Laboratory of the Universidade de Santiago de Compostela (Spain). We focus on the setup, the optimization of the operational parameters of the ESR spectrometer, the quantification of the readout signal and the construction of a calibration curve. The evaluation of the uncertainty budget is also a key component of an alanine/ESR system for radiotherapy dosimetry, and is presented in detail.After the optimization of the procedures, we have achieved a relative uncertainty of 1.7% (k=2) for an absorbed dose of 10 Gy, decreasing to 0.9% for 50 Gy.

  5. Assessment of skin dose for breast chest wall radiotherapy as a function of bolus material

    NASA Astrophysics Data System (ADS)

    Hsu, Shu-Hui; Roberson, Peter L.; Chen, Yu; Marsh, Robin B.; Pierce, Lori J.; Moran, Jean M.

    2008-05-01

    Skin dose assessment for chest wall radiotherapy is important to ensure sufficient dose to the surface target volume without excessive skin reaction. This study quantified changes to the surface doses as a function of bolus material for conventional and intensity modulated radiation therapy (IMRT) tangential fields. Three types of bolus materials (2 mm solid, 2 mm fine mesh and 3.2 mm large mesh Aquaplast) were compared with Superflab. Surface dose measurements were performed using an Attix parallel plate chamber in a flat solid water phantom at 0°, 45° and 70° incident angles. Over-response correction factors were applied to the Attix chamber results for different incident angles. Surface dose measurements on an anthropomorphic phantom were done using a thermoluminescent dosimeter extrapolation method. Dose characteristics of Superflab and solid Aquaplast were within 2% of solid water material. No significant differences (within 3%) in the surface dose were found between conventional and IMRT tangential techniques. The bolus effect was large for chest wall tangential radiotherapy, with up to an 82% increase using 2 mm fine mesh Aquaplast. The dosimetric effect of different Aquaplast materials has been quantified in this work. These materials can be used to create a custom bolus with potentially better reproducibility of placement.

  6. Whole brain radiotherapy plus simultaneous in-field boost with image guided intensity-modulated radiotherapy for brain metastases of non-small cell lung cancer

    PubMed Central

    2014-01-01

    Background Whole brain radiotherapy (WBRT) plus sequential focal radiation boost is a commonly used therapeutic strategy for patients with brain metastases. However, recent reports on WBRT plus simultaneous in-field boost (SIB) also showed promising outcomes. The objective of present study is to retrospectively evaluate the efficacy and toxicities of WBRT plus SIB with image guided intensity-modulated radiotherapy (IG-IMRT) for inoperable brain metastases of NSCLC. Methods Twenty-nine NSCLC patients with 87 inoperable brain metastases were included in this retrospective study. All patients received WBRT at a dose of 40 Gy/20 f, and SIB boost with IG-IMRT at a dose of 20 Gy/5 f concurrent with WBRT in the fourth week. Prior to each fraction of IG-IMRT boost, on-line positioning verification and correction were used to ensure that the set-up errors were within 2 mm by cone beam computed tomography in all patients. Results The one-year intracranial control rate, local brain failure rate, and distant brain failure rate were 62.9%, 13.8%, and 19.2%, respectively. The two-year intracranial control rate, local brain failure rate, and distant brain failure rate were 42.5%, 30.9%, and 36.4%, respectively. Both median intracranial progression-free survival and median survival were 10 months. Six-month, one-year, and two-year survival rates were 65.5%, 41.4%, and 13.8%, corresponding to 62.1%, 41.4%, and 10.3% of intracranial progression-free survival rates. Patients with Score Index for Radiosurgery in Brain Metastases (SIR) >5, number of intracranial lesions <3, and history of EGFR-TKI treatment had better survival. Three lesions (3.45%) demonstrated radiation necrosis after radiotherapy. Grades 2 and 3 cognitive impairment with grade 2 radiation leukoencephalopathy were observed in 4 (13.8%) and 4 (13.8%) patients. No dosimetric parameters were found to be associated with these late toxicities. Patients received EGFR-TKI treatment had higher incidence of grades 2–3

  7. A DVH-guided IMRT optimization algorithm for automatic treatment planning and adaptive radiotherapy replanning

    SciTech Connect

    Zarepisheh, Masoud; Li, Nan; Long, Troy; Romeijn, H. Edwin; Tian, Zhen; Jia, Xun; Jiang, Steve B.

    2014-06-15

    Purpose: To develop a novel algorithm that incorporates prior treatment knowledge into intensity modulated radiation therapy optimization to facilitate automatic treatment planning and adaptive radiotherapy (ART) replanning. Methods: The algorithm automatically creates a treatment plan guided by the DVH curves of a reference plan that contains information on the clinician-approved dose-volume trade-offs among different targets/organs and among different portions of a DVH curve for an organ. In ART, the reference plan is the initial plan for the same patient, while for automatic treatment planning the reference plan is selected from a library of clinically approved and delivered plans of previously treated patients with similar medical conditions and geometry. The proposed algorithm employs a voxel-based optimization model and navigates the large voxel-based Pareto surface. The voxel weights are iteratively adjusted to approach a plan that is similar to the reference plan in terms of the DVHs. If the reference plan is feasible but not Pareto optimal, the algorithm generates a Pareto optimal plan with the DVHs better than the reference ones. If the reference plan is too restricting for the new geometry, the algorithm generates a Pareto plan with DVHs close to the reference ones. In both cases, the new plans have similar DVH trade-offs as the reference plans. Results: The algorithm was tested using three patient cases and found to be able to automatically adjust the voxel-weighting factors in order to generate a Pareto plan with similar DVH trade-offs as the reference plan. The algorithm has also been implemented on a GPU for high efficiency. Conclusions: A novel prior-knowledge-based optimization algorithm has been developed that automatically adjust the voxel weights and generate a clinical optimal plan at high efficiency. It is found that the new algorithm can significantly improve the plan quality and planning efficiency in ART replanning and automatic treatment

  8. Kidney motion during free breathing and breath hold for MR-guided radiotherapy

    NASA Astrophysics Data System (ADS)

    Stam, Mette K.; van Vulpen, Marco; Barendrecht, Maurits M.; Zonnenberg, Bernard A.; Intven, Martijn; Crijns, Sjoerd P. M.; Lagendijk, Jan J. W.; Raaymakers, Bas W.

    2013-04-01

    Current treatments for renal cell carcinoma have a high complication rate due to the invasiveness of the treatment. With the MRI-linac it may be possible to treat renal tumours non-invasively with high-precision radiotherapy. This is expected to reduce complications. To deliver a static dose distribution, radiation gating will be used. In this study the reproducibility and efficiency of free breathing gating and a breath hold treatment of the kidney was investigated. For 15 patients with a renal lesion the kidney motion during 2 min of free breathing and 10 consecutive expiration breath holds was studied with 2D cine MRI. The variability in kidney expiration position and treatment efficiency for gating windows of 1 to 20 mm was measured for both breathing patterns. Additionally the time trend in free breathing and the variation in expiration breath hold kidney position with baseline shift correction was determined. In 80% of the patients the variation in expiration position during free breathing is smaller than 2 mm. No clinically relevant time trends were detected. The variation in expiration breath hold is for all patients larger than the free breathing expiration variation. Gating on free breathing is, for gating windows of 1 to 5 mm more efficient than breath hold without baseline correction. When applying a baseline correction to the breath hold it increases the treatment efficiency. The kidney position is more reproducible in expiration free breathing than non-guided expiration breath hold. For small gating windows it is also more time efficient. Since free breathing also seems more comfortable for the patients it is the preferred breathing pattern for MRI-Linac treatments of the kidney.

  9. Is internal target volume accurate for dose evaluation in lung cancer stereotactic body radiotherapy?

    PubMed Central

    Peng, Jiayuan; Zhang, Zhen; Wang, Jiazhou; Xie, Jiang; Hu, Weigang

    2016-01-01

    Purpose 4DCT delineated internal target volume (ITV) was applied to determine the tumor motion and used as planning target in treatment planning in lung cancer stereotactic body radiotherapy (SBRT). This work is to study the accuracy of using ITV to predict the real target dose in lung cancer SBRT. Materials and methods Both for phantom and patient cases, the ITV and gross tumor volumes (GTVs) were contoured on the maximum intensity projection (MIP) CT and ten CT phases, respectively. A SBRT plan was designed using ITV as the planning target on average projection (AVG) CT. This plan was copied to each CT phase and the dose distribution was recalculated. The GTV_4D dose was acquired through accumulating the GTV doses over all ten phases and regarded as the real target dose. To analyze the ITV dose error, the ITV dose was compared to the real target dose by endpoints of D99, D95, D1 (doses received by the 99%, 95% and 1% of the target volume), and dose coverage endpoint of V100(relative volume receiving at least the prescription dose). Results The phantom study shows that the ITV underestimates the real target dose by 9.47%∼19.8% in D99, 4.43%∼15.99% in D95, and underestimates the dose coverage by 5% in V100. The patient cases show that the ITV underestimates the real target dose and dose coverage by 3.8%∼10.7% in D99, 4.7%∼7.2% in D95, and 3.96%∼6.59% in V100 in motion target cases. Conclusions Cautions should be taken that ITV is not accurate enough to predict the real target dose in lung cancer SBRT with large tumor motions. Restricting the target motion or reducing the target dose heterogeneity could reduce the ITV dose underestimation effect in lung SBRT. PMID:26968812

  10. Automated Extraction of Dose/Volume Statistics for Radiotherapy-Treatment-Plan Evaluation in Clinical-Trial Quality Assurance

    PubMed Central

    Gong, Yutao U. T.; Yu, Jialu; Pang, Dalong; Zhen, Heming; Galvin, James; Xiao, Ying

    2016-01-01

    Radiotherapy clinical-trial quality assurance is a crucial yet challenging process. This note presents a tool that automatically extracts dose/volume statistics for determining dosimetry compliance review with improved efficiency and accuracy. A major objective of this study is to develop an automated solution for clinical-trial radiotherapy dosimetry review. PMID:26973814

  11. On the Use of Optically Stimulated Luminescent Dosimeter for Surface Dose Measurement during Radiotherapy.

    PubMed

    Yusof, Fasihah Hanum; Ung, Ngie Min; Wong, Jeannie Hsiu Ding; Jong, Wei Loong; Ath, Vannyat; Phua, Vincent Chee Ee; Heng, Siew Ping; Ng, Kwan Hoong

    2015-01-01

    This study was carried out to investigate the suitability of using the optically stimulated luminescence dosimeter (OSLD) in measuring surface dose during radiotherapy. The water equivalent depth (WED) of the OSLD was first determined by comparing the surface dose measured using the OSLD with the percentage depth dose at the buildup region measured using a Markus ionization chamber. Surface doses were measured on a solid water phantom using the OSLD and compared against the Markus ionization chamber and Gafchromic EBT3 film measurements. The effect of incident beam angles on surface dose was also studied. The OSLD was subsequently used to measure surface dose during tangential breast radiotherapy treatments in a phantom study and in the clinical measurement of 10 patients. Surface dose to the treated breast or chest wall, and on the contralateral breast were measured. The WED of the OSLD was found to be at 0.4 mm. For surface dose measurement on a solid water phantom, the Markus ionization chamber measured 15.95% for 6 MV photon beam and 12.64% for 10 MV photon beam followed by EBT3 film (23.79% and 17.14%) and OSLD (37.77% and 25.38%). Surface dose increased with the increase of the incident beam angle. For phantom and patient breast surface dose measurement, the response of the OSLD was higher than EBT3 film. The in-vivo measurements were also compared with the treatment planning system predicted dose. The OSLD measured higher dose values compared to dose at the surface (Hp(0.0)) by a factor of 2.37 for 6 MV and 2.01 for 10 MV photon beams, respectively. The measurement of absorbed dose at the skin depth of 0.4 mm by the OSLD can still be a useful tool to assess radiation effects on the skin dermis layer. This knowledge can be used to prevent and manage potential acute skin reaction and late skin toxicity from radiotherapy treatments. PMID:26052690

  12. On the Use of Optically Stimulated Luminescent Dosimeter for Surface Dose Measurement during Radiotherapy

    PubMed Central

    Yusof, Fasihah Hanum; Ung, Ngie Min; Wong, Jeannie Hsiu Ding; Jong, Wei Loong; Ath, Vannyat; Phua, Vincent Chee Ee; Heng, Siew Ping; Ng, Kwan Hoong

    2015-01-01

    This study was carried out to investigate the suitability of using the optically stimulated luminescence dosimeter (OSLD) in measuring surface dose during radiotherapy. The water equivalent depth (WED) of the OSLD was first determined by comparing the surface dose measured using the OSLD with the percentage depth dose at the buildup region measured using a Markus ionization chamber. Surface doses were measured on a solid water phantom using the OSLD and compared against the Markus ionization chamber and Gafchromic EBT3 film measurements. The effect of incident beam angles on surface dose was also studied. The OSLD was subsequently used to measure surface dose during tangential breast radiotherapy treatments in a phantom study and in the clinical measurement of 10 patients. Surface dose to the treated breast or chest wall, and on the contralateral breast were measured. The WED of the OSLD was found to be at 0.4 mm. For surface dose measurement on a solid water phantom, the Markus ionization chamber measured 15.95% for 6 MV photon beam and 12.64% for 10 MV photon beam followed by EBT3 film (23.79% and 17.14%) and OSLD (37.77% and 25.38%). Surface dose increased with the increase of the incident beam angle. For phantom and patient breast surface dose measurement, the response of the OSLD was higher than EBT3 film. The in-vivo measurements were also compared with the treatment planning system predicted dose. The OSLD measured higher dose values compared to dose at the surface (Hp(0.0)) by a factor of 2.37 for 6 MV and 2.01 for 10 MV photon beams, respectively. The measurement of absorbed dose at the skin depth of 0.4 mm by the OSLD can still be a useful tool to assess radiation effects on the skin dermis layer. This knowledge can be used to prevent and manage potential acute skin reaction and late skin toxicity from radiotherapy treatments. PMID:26052690

  13. Progressive cone beam CT dose control in image-guided radiation therapy

    SciTech Connect

    Yan Hao; Cervino, Laura; Jiang, Steve B.; Jia Xun; Zhen Xin

    2013-06-15

    Purpose: Cone beam CT (CBCT) in image-guided radiotherapy (IGRT) offers a tremendous advantage for treatment guidance. The associated imaging dose is a clinical concern. One unique feature of CBCT-based IGRT is that the same patient is repeatedly scanned during a treatment course, and the contents of CBCT images at different fractions are similar. The authors propose a progressive dose control (PDC) scheme to utilize this temporal correlation for imaging dose reduction. Methods: A dynamic CBCT scan protocol, as opposed to the static one in the current clinical practice, is proposed to gradually reduce the imaging dose in each treatment fraction. The CBCT image from each fraction is processed by a prior-image based nonlocal means (PINLM) module to enhance its quality. The increasing amount of prior information from previous CBCT images prevents degradation of image quality due to the reduced imaging dose. Two proof-of-principle experiments have been conducted using measured phantom data and Monte Carlo simulated patient data with deformation. Results: In the measured phantom case, utilizing a prior image acquired at 0.4 mAs, PINLM is able to improve the image quality of a CBCT acquired at 0.2 mAs by reducing the noise level from 34.95 to 12.45 HU. In the synthetic patient case, acceptable image quality is maintained at four consecutive fractions with gradually decreasing exposure levels of 0.4, 0.1, 0.07, and 0.05 mAs. When compared with the standard low-dose protocol of 0.4 mAs for each fraction, an overall imaging dose reduction of more than 60% is achieved. Conclusions: PINLM-PDC is able to reduce CBCT imaging dose in IGRT utilizing the temporal correlations among the sequence of CBCT images while maintaining the quality.

  14. Low-Dose Involved-Field Radiotherapy as Alternative Treatment of Nodular Lymphocyte Predominance Hodgkin's Lymphoma

    SciTech Connect

    Haas, Rick L.M. Girinsky, Theo; Aleman, Berthe; Henry-Amar, Michel; Boer, Jan-Paul de; Jong, Daphne de

    2009-07-15

    Purpose: Nodular lymphocyte predominance Hodgkin's lymphoma is a very rare disease, characterized by an indolent clinical course, with sometimes very late relapses occurring in a minority of all patients. Considerable discussion is ongoing on the treatment of primary and relapsed disease. Patients and Methods: A group of 9 patients were irradiated to a dose of 4 Gy on involved areas only. Results: After a median follow-up of 37 months (range, 6-66), the overall response rate was 89%. Six patients had complete remission (67%), two had partial remission (22%), and one had stable disease (11%). Of 8 patients, 5 developed local relapse 9-57 months after radiotherapy. No toxicity was noted. Conclusion: In nodular lymphocyte predominance Hodgkin's lymphoma, low-dose radiotherapy provided excellent response rates and lasting remissions without significant toxicity.

  15. Feasibility of normal tissue dose reduction in radiotherapy using low strength magnetic field

    PubMed Central

    Shin, Youngseob; Jung, In-Hye; Kwak, Jungwon

    2015-01-01

    Purpose Toxicity of mucosa is one of the major concerns of radiotherapy (RT), when a target tumor is located near a mucosal lined organ. Energy of photon RT is transferred primarily by secondary electrons. If these secondary electrons could be removed in an internal cavity of mucosal lined organ, the mucosa will be spared without compromising the target tumor dose. The purpose of this study was to present a RT dose reduction in near target inner-surface (NTIS) of internal cavity, using Lorentz force of magnetic field. Materials and Methods Tissue equivalent phantoms, composed with a cylinder shaped internal cavity, and adjacent a target tumor part, were developed. The phantoms were irradiated using 6 MV photon beam, with or without 0.3 T of perpendicular magnetic field. Two experimental models were developed: single beam model (SBM) to analyze central axis dose distributions and multiple beam model (MBM) to simulate a clinical case of prostate cancer with rectum. RT dose of NTIS of internal cavity and target tumor area (TTA) were measured. Results With magnetic field applied, bending effect of dose distribution was visualized. The depth dose distribution of SBM showed 28.1% dose reduction of NTIS and little difference in dose of TTA with magnetic field. In MBM, cross-sectional dose of NTIS was reduced by 33.1% with magnetic field, while TTA dose were the same, irrespective of magnetic field. Conclusion RT dose of mucosal lined organ, located near treatment target, could be modulated by perpendicular magnetic field. PMID:26484306

  16. Development of a MicroCT-Based Image-Guided Conformal Radiotherapy System for Small Animals

    PubMed Central

    Zhou, Hu; Rodriguez, Manuel; van den Haak, Fred; Nelson, Geoffrey; Jogani, Rahil; Xu, Jiali; Zhu, Xinzhi; Xian, Yongjiang; Tran, Phuoc T.; Felsher, Dean W.; Keall, Paul J.; Graves, Edward E.

    2009-01-01

    Purpose The need for clinically-relevant radiation therapy technology for the treatment of preclinical models of disease has spurred the development of a variety of dedicated platforms for small animal irradiation. Our group has taken the approach of adding the ability to deliver conformal radiotherapy to an existing 120 kVp micro-computed tomography (microCT) scanner. Methods A GE eXplore RS120 microCT scanner was modified by the addition of a two-dimensional subject translation stage and a variable aperture collimator. Quality assurance protocols for these devices, including measurement of translation stage positioning accuracy, collimator aperture accuracy, and collimator alignment with the x-ray beam, were devised. Use of this system for image-guided radiotherapy was assessed by irradiation of a solid water phantom as well as of two mice bearing spontaneous MYC-induced lung tumors. Radiation damage was assessed ex vivo by immunohistochemical detection of γH2AX foci. Results The positioning error of the translation stage was found to be less than 0.05 mm, while after alignment of the collimator with the x-ray axis through adjustment of its displacement and rotation, the collimator aperture error was less than 0.1 mm measured at isocenter. CT image-guided treatment of a solid water phantom demonstrated target localization accuracy to within 0.1 mm. γH2AX foci were detected within irradiated lung tumors in mice, with contralateral lung tissue displaying background staining. Conclusions Addition of radiotherapy functionality to a microCT scanner is an effective means of introducing image-guided radiation treatments into the preclinical setting. This approach has been shown to facilitate small animal conformal radiotherapy while leveraging existing technology. PMID:20395069

  17. Measurement of radiation dose with BeO dosimeters using optically stimulated luminescence technique in radiotherapy applications.

    PubMed

    Şahin, Serdar; Güneş Tanır, A; Meriç, Niyazi; Aydınkarahaliloğlu, Ercan

    2015-09-01

    The radiation dose delivered to the target by using different radiotherapy applications has been measured with the help of beryllium oxide (BeO) dosimeters to be placed inside the rando phantom. Three-Dimensional Conformal Radiotherapy (3DCRT), Intensity-Modulated Radiotherapy (IMRT) and Intensity-Modulated Arc Therapy (IMAT) have been used as radiotherapy application. Individual treatment plans have been made for the three radiotherapy applications of rando phantom. The section 4 on the phantom was selected as target and 200 cGy doses were delivered. After the dosimeters placed on section 4 (target) and the sections 2 and 6 (non-target) were irradiated, the result was read through the OSL technique on the Risø TL/OSL system. This procedure was repeated three times for each radiotherapy application. The doses delivered to the target and the non-target sections as a result of the 3DCRT, IMRT and IMAT plans were analyzed. The doses received by the target were measured as 204.71 cGy, 204.76 cGy and 205.65 cGy, respectively. The dose values obtained from treatment planning system (TPS) were compared to the dose values obtained using the OSL technique. It has been concluded that, the radiation dose can be measured with the OSL technique by using BeO dosimeters in medical practices. PMID:26046521

  18. Phantom validation of coregistration of PET and CT for image-guided radiotherapy.

    PubMed

    Lavely, William C; Scarfone, Christopher; Cevikalp, Hakan; Li, Rui; Byrne, Daniel W; Cmelak, Anthony J; Dawant, Benoit; Price, Ronald R; Hallahan, Dennis E; Fitzpatrick, J Michael

    2004-05-01

    /PET Fusion = 1.66 +/- 0.53 mm, AMIR = 1.15 +/- 0.48 mm. Precision (repeatability by a single user) measured for CT/PET Fusion: IAEA phantom = 1.59 +/- 0.67 mm and anthropomorphic head phantom = 1.63 +/- 0.52 mm. (AMIR has exact precision and so no measurements are necessary.) One sample patient demonstrated the following accuracy results: CT/PET Fusion = 3.89 +/- 1.61 mm, AMIR = 2.86 +/- 0.60 mm. Semi-automatic and automatic image registration methods may be used to facilitate incorporation of PET data into radiotherapy treatment planning in relatively rigid anatomic sites, such as head and neck. The overall accuracies in phantom and patient images are < 2 mm and < 4 mm, respectively, using either registration algorithm. Registration accuracy may decrease, however, as distance from the initial registration points (CT/PET fusion) or center of the image (AMIR) increases. Additional information provided by PET may improve dose coverage to active tumor subregions and hence tumor control. This study shows that the accuracy obtained by image registration with these two methods is well suited for image-guided radiotherapy. PMID:15191296

  19. Derivation and representation of dose-volume response from large clinical trial data sets: an example from the RADAR prostate radiotherapy trial

    NASA Astrophysics Data System (ADS)

    Ebert, M. A.; Foo, K.; Haworth, A.; Gulliford, S. L.; Kearvall, R.; Kennedy, A.; Richardson, S.; Krawiec, M.; Stewart, N.; Joseph, D. J.; Denham, J. W.

    2014-03-01

    Large multicentre radiotherapy trials incorporating assessment of multiple outcomes at multiple timepoints can generate extensive datasets. We have investigated graphical techniques for presentation of this data and the associated underlying dose-volume response information, necessary for guiding statistical analyses and translating outcomes to future patient treatments. A relational database was used to archive reviewed plan data for patients accrued to the TROG 03.04 RADAR trial. Viewing software was used to clean and enhance the data. Scripts were developed to export arbitrary dose-histogram data which was combined with clinical toxicity data with a median follow-up of 72 months. Graphical representations of dose-volume response developed include prevalence atlasing, univariate logistic regression and dose-volume-point odds ratios, and continuous cut-point derivation via ROC analysis. These representations indicate variable association of toxicities across structures and time-points.

  20. Radiation Pneumonitis After Hypofractionated Radiotherapy: Evaluation of the LQ(L) Model and Different Dose Parameters

    SciTech Connect

    Borst, Gerben R.; Ishikawa, Masayori; Nijkamp, Jasper

    2010-08-01

    Purpose: To evaluate the linear quadratic (LQ) model for hypofractionated radiotherapy within the context of predicting radiation pneumonitis (RP) and to investigate the effect if a linear (L) model in the high region (LQL model) is used. Methods and Materials: The radiation doses used for 128 patients treated with hypofractionated radiotherapy were converted to the equivalent doses given in fractions of 2 Gy for a range of {alpha}/{beta} ratios (1 Gy to infinity) according to the LQ(L) model. For the LQL model, different cut-off values between the LQ model and the linear component were used. The Lyman model parameters were fitted to the events of RP grade 2 or higher to derive the normal tissue complication probability (NTCP). The lung dose was calculated as the mean lung dose and the percentage of lung volume (V) receiving doses higher than a threshold dose of xGy (V{sub x}). Results: The best NTCP fit was found if the mean lung dose, or V{sub x}, was calculated with an {alpha}/{beta} ratio of 3 Gy. The NTCP fit of other {alpha}/{beta} ratios and the LQL model were worse but within the 95% confidence interval of the NTCP fit of the LQ model with an {alpha}/{beta} ratio of 3 Gy. The V{sub 50} NTCP fit was better than the NTCP fit of lower threshold doses. Conclusions: For high fraction doses, the LQ model with an {alpha}/{beta} ratio of 3 Gy was the best method for converting the physical lung dose to predict RP.

  1. Dose characteristics of in-house-built collimators for stereotactic radiotherapy with a linear accelerator

    NASA Astrophysics Data System (ADS)

    Norrgård, F. Stefan E.; Sipilä, Petri M.; Kulmala, Jarmo A. J.; Minn, Heikki R. I.

    1998-06-01

    Dose characteristics of a stereotactic radiotherapy unit based on a standard Varian Clinac 4/100 4 MV linear accelerator, in-house-built Lipowitz collimators and the SMART stereotactic radiotherapy treatment planning software have been determined. Beam collimation is constituted from the standard collimators of the linear accelerator and a tertiary collimation consisting of a replaceable divergent Lipowitz collimator. Four collimators with isocentre diameters of 15, 25, 35 and 45 mm, respectively, were constructed. Beam characteristics were measured in air, acrylic or water with ionization chamber, photon diode, electron diode, diamond detector and film. Monte Carlo simulation was also applied. The radiation leakage under the collimators was less than 1% at 50 mm depth in water. Specific beam characteristics for each collimator were imported to SMART and dose planning with five non-coplanar converging arcs separated by angles was performed for treatment of a RANDO phantom. Dose verification was made with TLD and radiochromic film. The in-house-built collimators were found to be suitable for stereotactic radiotherapy and patient treatments with this system are in progress.

  2. External beam radiotherapy for palliation of painful bone metastases: pooled data bioeffect dose response analysis of dose fractionation

    NASA Astrophysics Data System (ADS)

    Naveen, T.; Supe, Sanjay S.; Ganesh, K. M.; Samuel, Jacob

    2009-01-01

    Bone metastases develop in up to 70% of newly diagnosed cancer patients and result in immobility, anxiety, and depression, severely diminishing the patients quality of life. Radiotherapy is a frequently used modality for bone metastasis and has been shown to be effective in reducing metastatic bone pain and in some instances, causing tumor shrinkage or growth inhibition. There is controversy surrounding the optimal fractionation schedule and total dose of external beam radiotherapy, despite many randomized trials and overviews addressing the issue. This study was undertaken to apply BED to clinical fractionation data of radiotherapeutic management of bone metastases in order to arrive at optimum BED values for acceptable level of response rate. A computerised literature search was conducted to identify all prospective clinical studies that addressed the issue of fractionation for the treatment of bone metastasis. The results of these studies were pooled together to form the database for the analysis. A total of 4111 number of patients received radiation dose ranging from 4 to 40.5 Gy in 1 to 15 fractions with dose per fraction ranging from 2 to 10 Gy. Single fraction treatments were delivered in 2013 patients and the dose varied from 4 to 10 Gy. Multifraction treatments were delivered in 2098 patients and the dose varied from 15 to 40.5 Gy. The biological effective dose (BED) was evaluated for each fractionation schedule using the linear quadratic model and an α/β value of 10 Gy. Response rate increased significantly beyond a BED value of 14.4 Gy (p < 0.01). Based on our analysis and indications from the literature about higher retreatment and fracture rate of single fraction treatments, minimum BED value of 14.4 Gy is recommended.

  3. Measuring radiation dose to patients undergoing fluoroscopically-guided interventions

    NASA Astrophysics Data System (ADS)

    Lubis, L. E.; Badawy, M. K.

    2016-03-01

    The increasing prevalence and complexity of fluoroscopically guided interventions (FGI) raises concern regarding radiation dose to patients subjected to the procedure. Despite current evidence showing the risk to patients from the deterministic effects of radiation (e.g. skin burns), radiation induced injuries remain commonplace. This review aims to increase the awareness surrounding radiation dose measurement for patients undergoing FGI. A review of the literature was conducted alongside previous researches from the authors’ department. Studies pertaining to patient dose measurement, its formalism along with current advances and present challenges were reviewed. Current patient monitoring techniques (using available radiation dosimeters), as well as the inadequacy of accepting displayed dose as patient radiation dose is discussed. Furthermore, advances in real-time patient radiation dose estimation during FGI are considered. Patient dosimetry in FGI, particularly in real time, remains an ongoing challenge. The increasing occurrence and sophistication of these procedures calls for further advances in the field of patient radiation dose monitoring. Improved measuring techniques will aid clinicians in better predicting and managing radiation induced injury following FGI, thus improving patient care.

  4. A magnetic vehicle realized tumor cell-targeted radiotherapy using low-dose radiation.

    PubMed

    Chen, Hsiao-Ping; Tung, Fu-I; Chen, Ming-Hong; Liu, Tse-Ying

    2016-03-28

    Radiotherapy, a common cancer treatment, often adversely affects the surrounding healthy tissue and/or cells. Some tumor tissue-focused radiation therapies have been developed to lower radiation-induced lesion formation; however, achieving tumor cell-targeted radiotherapy (i.e., precisely focusing the radiation efficacy to tumor cells) remains a challenge. In the present study, we developed a novel tumor cell-targeted radiotherapy, named targeted sensitization-enhanced radiotherapy (TSER), that exploits tumor-specific folic acid-conjugated carboxymethyl lauryl chitosan/superparamagnetic iron oxide (FA-CLC/SPIO) micelles to effectively deliver chlorin e6 (Ce6, a sonosensitizer) to mitochondria of HeLa cells under magnetic guidance. For the in vitro tests, the sensitization of Ce6 induced by ultrasound, that could weaken the radiation resistant ability of tumor cells, occurred only in Ce6-internalizing tumor cells. Therefore, low-dose X-ray irradiation, that was not harmful to normal cells, could exert high tumor cell-specific killing ability. The ratio of viable normal cells to tumor cells was increased considerably, from 7.8 (at 24h) to 97.1 (at 72h), after they had received TSER treatment. Our data suggest that TSER treatment significantly weakens tumor cells, resulting in decreased viability in vitro as well as decreased in vivo subcutaneous tumor growth in nude mice, while the adverse effects were minimal. Taken together, TSER treatment appears to be an effective, clinically feasible tumor cell-targeted radiotherapy that can solve the problems of traditional radiotherapy and photodynamic therapy. PMID:26892750

  5. Dose-distance metric that predicts late rectal bleeding in patients receiving radical prostate external-beam radiotherapy

    NASA Astrophysics Data System (ADS)

    Lee, Richard; Chan, Elisa K.; Kosztyla, Robert; Liu, Mitchell; Moiseenko, Vitali

    2012-12-01

    The relationship between rectal dose distribution and the incidence of late rectal complications following external-beam radiotherapy has been previously studied using dose-volume histograms or dose-surface histograms. However, they do not account for the spatial dose distribution. This study proposes a metric based on both surface dose and distance that can predict the incidence of rectal bleeding in prostate cancer patients treated with radical radiotherapy. One hundred and forty-four patients treated with radical radiotherapy for prostate cancer were prospectively followed to record the incidence of grade ≥2 rectal bleeding. Radiotherapy plans were used to evaluate a dose-distance metric that accounts for the dose and its spatial distribution on the rectal surface, characterized by a logistic weighting function with slope a and inflection point d0. This was compared to the effective dose obtained from dose-surface histograms, characterized by the parameter n which describes sensitivity to hot spots. The log-rank test was used to determine statistically significant (p < 0.05) cut-off values for the dose-distance metric and effective dose that predict for the occurrence of rectal bleeding. For the dose-distance metric, only d0 = 25 and 30 mm combined with a > 5 led to statistical significant cut-offs. For the effective dose metric, only values of n in the range 0.07-0.35 led to statistically significant cut-offs. The proposed dose-distance metric is a predictor of rectal bleeding in prostate cancer patients treated with radiotherapy. Both the dose-distance metric and the effective dose metric indicate that the incidence of grade ≥2 rectal bleeding is sensitive to localized damage to the rectal surface.

  6. Mutant frequency of radiotherapy technicians appears to be associated with recent dose of ionizing radiation

    SciTech Connect

    Messing, K.; Ferraris, J.; Bradley, W.E.; Swartz, J.; Seifert, A.M. )

    1989-10-01

    The frequency of hypoxanthine phosphoribosyl transferase (HPRT) mutants among peripheral T-lymphocytes of radiotherapy technicians primarily exposed to 60Co was measured by the T-cell cloning method. Mutant frequencies of these technicians in 1984 and 1986 were significantly higher than those of physiotherapy technicians who worked in a neighboring service, and correlated significantly with thermoluminescence dosimeter readings recorded during the 6 mo preceding mutant frequency determination. Correlations decreased when related to dose recorded over longer time intervals. HPRT mutant frequency determination in peripheral lymphocytes is a good measure of recently received biologically effective radiation dose in an occupationally exposed population.

  7. Verification of dose volume histograms in stereotactic radiosurgery and radiotherapy using polymer gel and MRI

    NASA Astrophysics Data System (ADS)

    Šemnická, Jitka; Novotný, Josef, Jr.; Spěváček, Václav; Garčic, Jirí; Steiner, Martin; Judas, Libor

    2006-12-01

    In this work we focus on dose volume histograms (DVHs) measurement in stereotactic radiosurgery (SR) performed with the Leksell gamma knife (ELEKTA Instrument AB, Stockholm, Sweden) and stereotactic radiotherapy (SRT) performed with linear accelerator 6 MV Varian Clinac 2100 C/D (Varian Medical Systems, Palo Alto, USA) in conjunction with BrainLAB stereotactic system (BrainLAB, Germany) using modified BANG gel and magnetic resonance imaging (MRI). The aim of the experiments was to investigate a method for acquiring entire dose volume information from irradiated gel dosimeter and calculate DVHs.

  8. Measurement of neutron ambient dose equivalent in carbon-ion radiotherapy with an active scanned delivery system.

    PubMed

    Yonai, S; Furukawa, T; Inaniwa, T

    2014-10-01

    In ion beam radiotherapy, secondary neutrons contribute to an undesired dose outside the target volume, and consequently the increase of secondary cancer risk is a growing concern. In this study, neutron ambient dose equivalents in carbon-ion radiotherapy (CIRT) with an active beam delivery system were measured with a rem meter, WENDI-II, at National Institute of Radiological Sciences. When the same irradiation target was assumed, the measured neutron dose with an active beam was at most ∼15 % of that with a passive beam. This percentage became smaller as larger distances from the iso-centre. Also, when using an active beam delivery system, the neutron dose per treatment dose in CIRT was comparable with that in proton radiotherapy. Finally, it was experimentally demonstrated that the use of an active scanned beam in CIRT can greatly reduce the secondary neutron dose. PMID:24126486

  9. Personnel radiation dose considerations in the use of an integrated PET-CT scanner for radiotherapy treatment planning.

    PubMed

    Carson, K J; Young, V A L; Cosgrove, V P; Jarritt, P H; Hounsell, A R

    2009-11-01

    The acquisition of radiotherapy planning scans on positron emission tomography (PET)-CT scanners requires the involvement of radiotherapy radiographers. This study assessed the radiation dose received by these radiographers during this process. Radiotherapy planning (18)F-fluorodeoxyglucose ((18)F-FDG) PET-CT scans were acquired for 28 non-small cell lung cancer patients. In order to minimise the radiation dose received, a two-stage process was used in which the most time-consuming part of the set-up was performed before the patient received their (18)F-FDG injection. Throughout this process, the radiographers wore electronic personal dosemeters and recorded the doses received at different stages of the process. The mean total radiation dose received by a radiotherapy radiographer was 5.1+/-2.6 microSv per patient. The use of the two-stage process reduced the time spent in close proximity to the patient by approximately a factor of four. The two-stage process was effective in keeping radiation dose to a minimum. The use of a pre-injection set-up session reduces the radiation dose to the radiotherapy radiographers because of their involvement in PET-CT radiotherapy treatment planning scans by approximately a factor of three. PMID:19332513

  10. Comparison of selected dose calculation algorithms in radiotherapy treatment planning for tissues with inhomogeneities

    NASA Astrophysics Data System (ADS)

    Woon, Y. L.; Heng, S. P.; Wong, J. H. D.; Ung, N. M.

    2016-03-01

    Inhomogeneity correction is recommended for accurate dose calculation in radiotherapy treatment planning since human body are highly inhomogeneous with the presence of bones and air cavities. However, each dose calculation algorithm has its own limitations. This study is to assess the accuracy of five algorithms that are currently implemented for treatment planning, including pencil beam convolution (PBC), superposition (SP), anisotropic analytical algorithm (AAA), Monte Carlo (MC) and Acuros XB (AXB). The calculated dose was compared with the measured dose using radiochromic film (Gafchromic EBT2) in inhomogeneous phantoms. In addition, the dosimetric impact of different algorithms on intensity modulated radiotherapy (IMRT) was studied for head and neck region. MC had the best agreement with the measured percentage depth dose (PDD) within the inhomogeneous region. This was followed by AXB, AAA, SP and PBC. For IMRT planning, MC algorithm is recommended for treatment planning in preference to PBC and SP. The MC and AXB algorithms were found to have better accuracy in terms of inhomogeneity correction and should be used for tumour volume within the proximity of inhomogeneous structures.

  11. Dose-Volume Histogram Analysis of Stereotactic Body Radiotherapy Treatment of Pancreatic Cancer: A Focus on Duodenal Dose Constraints.

    PubMed

    Goldsmith, Christy; Price, Patricia; Cross, Timothy; Loughlin, Sheila; Cowley, Ian; Plowman, Nicholas

    2016-04-01

    Pancreatic carcinoma is an aggressive disease and radiotherapy treatment delivery to the primary tumor is constrained by the anatomical close location of the duodenum, stomach, and small bowel. Duodenal dose tolerance for radiosurgery in 2-5 fractions has been largely unknown. The literature was surveyed for quantitative models of risk in 1-5 fractions and we analyzed our own patient population of 44 patients with unresectable pancreatic tumors who received 3 or 5 fractions of stereotactic body radiotherapy (SBRT) between March 2009 and March 2013. A logistic model was constructed in the dose-volume histogram (DVH) Evaluator software for the duodenal D50%, D30cc, D5cc, D1cc, and maximum point dose D0.035cc. Dose tolerance limits from the literature were overlaid onto the clinical duodenal data in the form of a DVH Risk Map, with risk levels of the published limits estimated from the model of clinical data. In 3 fractions, Kopek 2010 found a statistically significant difference in D1cc of patients with no common terminology criteria for adverse events (CTCAE) v3 grade 2 or higher duodenal complications (mean D1cc = 25.3Gy) as compared with patients with grade 2 or higher toxicity (mean D1cc = 37.4Gy). From the logistic model of our duodenal data in 3 fractions, D1cc = 25.3Gy had 4.7% risk of grade 3-4 hemorrhage or stricture and D1cc = 37.4Gy had 20% risk. The 10% risk level was D1cc = 31.4Gy and we were able to keep duodenum dose for all our patients later this level. PMID:27000512

  12. Dose-Effect Relationships for Individual Pelvic Floor Muscles and Anorectal Complaints After Prostate Radiotherapy

    SciTech Connect

    Smeenk, Robert Jan; Hoffmann, Aswin L.; Hopman, Wim P.M.; Lin, Emile N.J. Th. van; Kaanders, Johannes H.A.M.

    2012-06-01

    Purpose: To delineate the individual pelvic floor muscles considered to be involved in anorectal toxicity and to investigate dose-effect relationships for fecal incontinence-related complaints after prostate radiotherapy (RT). Methods and Materials: In 48 patients treated for localized prostate cancer, the internal anal sphincter (IAS) muscle, the external anal sphincter (EAS) muscle, the puborectalis muscle (PRM), and the levator ani muscles (LAM) in addition to the anal wall (Awall) and rectal wall (Rwall) were retrospectively delineated on planning computed tomography scans. Dose parameters were obtained and compared between patients with and without fecal urgency, incontinence, and frequency. Dose-effect curves were constructed. Finally, the effect of an endorectal balloon, which was applied in 28 patients, was investigated. Results: The total volume of the pelvic floor muscles together was about three times that of the Awall. The PRM was exposed to the highest RT dose, whereas the EAS received the lowest dose. Several anal and rectal dose parameters, as well as doses to all separate pelvic floor muscles, were associated with urgency, while incontinence was associated mainly with doses to the EAS and PRM. Based on the dose-effect curves, the following constraints regarding mean doses could be deduced to reduce the risk of urgency: {<=}30 Gy to the IAS; {<=}10 Gy to the EAS; {<=}50 Gy to the PRM; and {<=}40 Gy to the LAM. No dose-effect relationships for frequency were observed. Patients treated with an endorectal balloon reported significantly less urgency and incontinence, while their treatment plans showed significantly lower doses to the Awall, Rwall, and all pelvic floor muscles. Conclusions: Incontinence-related complaints show specific dose-effect relationships to individual pelvic floor muscles. Dose constraints for each muscle can be identified for RT planning. When only the Awall is delineated, substantial components of the continence apparatus are

  13. Stereotactic Image-Guided Intensity Modulated Radiotherapy Using the HI-ART II Helical Tomotherapy System

    SciTech Connect

    Holmes, Timothy W. Hudes, Richard; Dziuba, Sylwester; Kazi, Abdul; Hall, Mark; Dawson, Dana

    2008-07-01

    The highly integrated adaptive radiation therapy (HI-ART II) helical tomotherapy unit is a new radiotherapy machine designed to achieve highly precise and accurate treatments at all body sites. The precision and accuracy of the HI-ART II is similar to that provided by stereotactic radiosurgery systems, hence the historical distinction between external beam radiotherapy and stereotactic procedures based on differing precision requirements is removed for this device. The objectives of this work are: (1) to describe stereotactic helical tomotherapy processes (SRS, SBRT); (2) to show that the precision and accuracy of the HI-ART meet the requirements defined for SRS and SBRT; and (3) to describe the clinical implementation of a stereotactic image-guided intensity modulated radiation therapy (IG-IMRT) system that incorporates optical motion management.

  14. [Single-dose palliative radiotherapy in inoperable non-small-cell lung carcinoma].

    PubMed

    Scolaro, T; Bacigalupo, A; Giudici, S; Guenzi, M; Vitale, V

    1995-12-01

    The treatment of choice for advanced inoperable non-small cell lung cancer (NSCLC) is radiation therapy. Palliative radiotherapy schedules vary considerably in different centers, but a 30-Gy dose given in ten fractions over two weeks is a typical standard schedule. Our study was aimed at investigating whether a shorter course of only one 10-Gy fraction allows good palliation in the treatment of inoperable NSCLC patients whose main symptoms are related to an intrathoracic lesion. Patients of both sexes and any age, untreated with radiotherapy, with inoperable and histologically or cytologically proved NSCLC were examined. Seventeen patients, too advanced for radical "curative" radiotherapy and whose main symptoms were related to primary intrathoracic lesions, entered the study even though they had metastases. On admission, 76% (13/17) of patients had cough 76% (13/17) dyspnea, 70.7% (12/17) chest pain and 23.6% (4/17) hemoptysis. They received a single dose of 10 Gy, delivered with an 18-Mv linear accelerator via anteroposteriorly opposing portals without spinal cord shielding. Treatment volume usually included the macroscopically detected lesion identified with a CT simulator. Palliation of symptoms was achieved in high rates of patients: 46% for cough, 69% for dyspnea, 83% for pain and 75% for hemoptysis. These results were obtained within one month of treatment. Unfortunately, palliation of symptoms did not last long, decreasing to 42% within two months of the end of treatment and to 32% at three months. Four patients were retreated, one patient three months and three patients two months after the end of radiotherapy. Ten Gy to the target volume were administered as retreatment with spinal cord shielding. Side-effects were mild: nausea in 3 patients (17%), vomiting in one patient (5%) and grade-II dysphagia in two patients were observed and classified according to WHO criteria. Pain increased 24 hours after radiotherapy in five patients. We can conclude that

  15. Measurement of radiotherapy superficial X-ray dose under eye shields with radiochromic film.

    PubMed

    Butson, Martin J; Cheung, Tsang; Yu, Peter K N; Price, Sian; Bailey, Michael

    2008-03-01

    Accurate measurement and knowledge of dose delivered under eye shield during superficial X-ray radiotherapy is required for patient peripheral dose assessment. Critical structures can include the cornea, lens and retina. Measurement of dose under eye shields has been historically performed with Thermoluminescent Dosimeters (TLD's) due to their small size and design. Restrictions include the energy dependence and the fact that they only provide a point dose assessment. This note investigates the use of a low energy dependence radiochromic thin film for measurement of dose under eye shields in a phantom and compares results to theoretical calculation of dose. Results have shown a good match between predicted and experimentally measured results at the centre of an eye shield irradiated with 50kVp and 150kVp beams. The added advantage of radiochromic film compared to TLD measurements is the two dimensional dose map which is recorded for the assessment of dose providing not only an assessment at the site of the cornea, lens and retina in a phantom but in other areas as well. Radiochromic film has been found to accurately measure dose under eye shield in phantom treatments. PMID:18162428

  16. MRI-guided tumor tracking in lung cancer radiotherapy

    NASA Astrophysics Data System (ADS)

    Cerviño, Laura I.; Du, Jiang; Jiang, Steve B.

    2011-07-01

    Precise tracking of lung tumor motion during treatment delivery still represents a challenge in radiation therapy. Prototypes of MRI-linac hybrid systems are being created which have the potential of ionization-free real-time imaging of the tumor. This study evaluates the performance of lung tumor tracking algorithms in cine-MRI sagittal images from five healthy volunteers. Visible vascular structures were used as targets. Volunteers performed several series of regular and irregular breathing. Two tracking algorithms were implemented and evaluated: a template matching (TM) algorithm in combination with surrogate tracking using the diaphragm (surrogate was used when the maximum correlation between the template and the image in the search window was less than specified), and an artificial neural network (ANN) model based on the principal components of a region of interest that encompasses the target motion. The mean tracking error ē and the error at 95% confidence level e95 were evaluated for each model. The ANN model led to ē = 1.5 mm and e95 = 4.2 mm, while TM led to ē = 0.6 mm and e95 = 1.0 mm. An extra series was considered separately to evaluate the benefit of using surrogate tracking in combination with TM when target out-of-plane motion occurs. For this series, the mean error was 7.2 mm using only TM and 1.7 mm when the surrogate was used in combination with TM. Results show that, as opposed to tracking with other imaging modalities, ANN does not perform well in MR-guided tracking. TM, however, leads to highly accurate tracking. Out-of-plane motion could be addressed by surrogate tracking using the diaphragm, which can be easily identified in the images.

  17. Low-Dose-Rate Californium-252 Neutron Intracavitary Afterloading Radiotherapy Combined With Conformal Radiotherapy for Treatment of Cervical Cancer

    SciTech Connect

    Zhang Min; Xu Hongde; Pan Songdan; Lin Shan; Yue Jianhua; Liu Jianren

    2012-07-01

    Purpose: To study the efficacy of low-dose-rate californium-252 ({sup 252}Cf) neutron intracavitary afterloading radiotherapy (RT) combined with external pelvic RT for treatment of cervical cancer. Methods and Materials: The records of 96 patients treated for cervical cancer from 2006 to 2010 were retrospectively reviewed. For patients with tumors {<=}4 cm in diameter, external beam radiation was performed (1.8 Gy/day, five times/week) until the dose reached 20 Gy, and then {sup 252}Cf neutron intracavitary afterloading RT (once/week) was begun, and the frequency of external beam radiation was changed to four times/week. For patients with tumors >4 cm, {sup 252}Cf RT was performed one to two times before whole-pelvis external beam radiation. The tumor-eliminating dose was determined by using the depth limit of 5 mm below the mucosa as the reference point. In all patients, the total dose of the external beam radiation ranged from 46.8 to 50 Gy. For {sup 252}Cf RT, the dose delivered to point A was 6 Gy/fraction, once per week, for a total of seven times, and the total dose was 42 Gy. Results: The mean {+-} SD patient age was 54.7 {+-} 13.7 years. Six patients had disease assessed at stage IB, 13 patients had stage IIA, 49 patients had stage IIB, 3 patients had stage IIIA, 24 patients had stage IIIB, and 1 patient had stage IVA. All patients obtained complete tumor regression (CR). The mean {+-} SD time to CR was 23.5 {+-} 3.4 days. Vaginal bleeding was fully controlled in 80 patients within 1 to 8 days. The mean {+-} SD follow-up period was 27.6 {+-} 12.7 months (range, 6-48 months). Five patients died due to recurrence or metastasis. The 3-year survival and disease-free recurrence rates were 89.6% and 87.5 %, respectively. Nine patients experienced mild radiation proctitis, and 4 patients developed radiocystitis. Conclusions: Low-dose-rate {sup 252}Cf neutron RT combined with external pelvic RT is effective for treating cervical cancer, with a low incidence of

  18. Clinical Outcomes of Patients Receiving Integrated PET/CT-Guided Radiotherapy for Head and Neck Carcinoma

    SciTech Connect

    Vernon, Matthew R.; Maheshwari, Mohit; Schultz, Christopher J.; Michel, Michelle A.; Wong, Stuart J.; Campbell, Bruce H.; Massey, Becky L.; Wilson, J. Frank; Wang Dian

    2008-03-01

    Purpose: We previously reported the advantages of {sup 18}F-fluorodeoxyglucose-positron emission tomography (PET) fused with CT for radiotherapy planning over CT alone in head and neck carcinoma (HNC). The purpose of this study was to evaluate clinical outcomes and the predictive value of PET for patients receiving PET/CT-guided definitive radiotherapy with or without chemotherapy. Methods and Materials: From December 2002 to August 2006, 42 patients received PET/CT imaging as part of staging and radiotherapy planning. Clinical outcomes including locoregional recurrence, distant metastasis, death, and treatment-related toxicities were collected retrospectively and analyzed for disease-free and overall survival and cumulative incidence of recurrence. Results: Median follow-up from initiation of treatment was 32 months. Overall survival and disease-free survival were 82.8% and 71.0%, respectively, at 2 years, and 74.1% and 66.9% at 3 years. Of the 42 patients, seven recurrences were identified (three LR, one DM, three both LR and DM). Mean time to recurrence was 9.4 months. Cumulative risk of recurrence was 18.7%. The maximum standard uptake volume (SUV) of primary tumor, adenopathy, or both on PET did not correlate with recurrence, with mean values of 12.0 for treatment failures vs. 11.7 for all patients. Toxicities identified in those patients receiving intensity modulated radiation therapy were also evaluated. Conclusions: A high level of disease control combined with favorable toxicity profiles was achieved in a cohort of HNC patients receiving PET/CT fusion guided radiotherapy plus/minus chemotherapy. Maximum SUV of primary tumor and/or adenopathy was not predictive of risk of disease recurrence.

  19. Lung dose analysis in loco-regional hypofractionated radiotherapy of breast cancer

    PubMed Central

    Attar, Mohammad A.; Bahadur, Yasir A.; Constantinescu, Camelia T.; Eltaher, Maha M.

    2016-01-01

    Objectives: To report the ipsilateral lung dosimetry data of breast cancer (BC) patients treated with loco-regional hypofractionated radiotherapy (HFRT). Methods: Treatment plans of 150 patients treated in the Radiotherapy Unit, King Abdulaziz University Hospital, Jeddah, Kingdom of Saudi Arabia between January 2012 and March 2015 by HFRT for BC were retrospectively reviewed. All patients received 42.4 Gy in 16 fractions by tangential and supra-clavicular fields with 6 MV, 18 MV, or mixed energies. Ipsilateral lung dosimetric data V20Gy and mean lung dose (MLD) were recorded. Correlations between lung dose, patient characteristics, and treatment delivery parameters were assessed by a logistic regression test. Results: The mean ipsilateral lung V20Gy was 24.6% and mean MLD was 11.9 Gy. A weak, but statistically significant correlation was found between lung dose and lung volume (p=0.043). The lung dose was significantly decreasing with patient separation and depth of axillary lymph node (ALN) and supra-claviculary lymph nodes (SCLN) (p<0.0001), and increasing with ALN (p=0.001) and SCLN (p=0.003) dose coverage. Lung dose significantly decreased with beam energy (p<0.0001): mean V20Gy was 27.8%, 25.4% for 6 MV, mixed energy, and 21.2% for 18 MV. The use of a low breast-board angle correlates with low lung dose. Conclusion: Our data suggest that the use of high energy photon beams and low breast-board angulation can reduce the lung dose. PMID:27279508

  20. Prospective Trial of High-Dose Reirradiation Using Daily Image Guidance With Intensity-Modulated Radiotherapy for Recurrent and Second Primary Head-and-Neck Cancer

    SciTech Connect

    Chen, Allen M.; Farwell, D. Gregory; Luu, Quang; Cheng, Suzan; Donald, Paul J.; Purdy, James A.

    2011-07-01

    Purpose: To report a single-institutional experience using intensity-modulated radiotherapy with daily image-guided radiotherapy for the reirradiation of recurrent and second cancers of the head and neck. Methods and Materials: Twenty-one consecutive patients were prospectively treated with intensity-modulated radiotherapy from February 2006 to March 2009 to a median dose of 66 Gy (range, 60-70 Gy). None of these patients received concurrent chemotherapy. Daily helical megavoltage CT scans were obtained before each fraction as part of an image-guided radiotherapy registration protocol for patient alignment. Results: The 1- and 2-year estimates of in-field control were 72% and 65%, respectively. A total of 651 daily megavoltage CT scans were obtained. The mean systematic shift to account for interfraction motion was 1.38 {+-} 1.25 mm, 1.79 {+-} 1.45 mm, and 1.98 {+-} 1.75 mm for the medial-lateral, superior-inferior, and anterior-posterior directions, respectively. Pretreatment shifts of >3 mm occurred in 19% of setups in the medial-lateral, 27% in the superior-inferior, and 33% in the anterior-posterior directions, respectively. There were no treatment-related fatalities or hospitalizations. Complications included skin desquamation, odynophagia, otitis externa, keratitis, naso-lacrimal duct stenosis, and brachial plexopathy. Conclusions: Intensity-modulated radiotherapy with daily image guidance results in effective disease control with relatively low morbidity and should be considered for selected patients with recurrent and second primary cancers of the head and neck.

  1. Assessment of contralateral mammary gland dose in the treatment of breast cancer using accelerated hypofractionated radiotherapy

    PubMed Central

    Tolia, Maria; Platoni, Kalliopi; Foteineas, Andreas; Kalogeridi, Maria-Aggeliki; Zygogianni, Anna; Tsoukalas, Nikolaos; Caimi, Mariangela; Margari, Niki; Dilvoi, Maria; Pantelakos, Panagiotis; Kouvaris, John; Kouloulias, Vassilis

    2011-01-01

    AIM: To measure the dose distribution, related to the treatment planning calculations, in the contralateral mammary gland of breast cancer patients treated with accelerated hypofractionated 3-dimensional conformal radiotherapy. METHODS: Thirty-four prospectively selected female patients with right breast cancer (pN0, negative surgical margins) were treated with breast-conserving surgery. A total dose of 42.5 Gy (2.66 Gy/fraction) was prescribed; it was requested that planning target volumes be covered by the 95% isodose line. The contralateral mammary gland was defined on CT simulation. The dose received was evaluated by dose volume histograms. RESULTS: The measured contralateral breast doses were: (1) Dose maximum: 290-448 cGy [Equivalent (Eq) 337-522 cGy]; (2) Mean dose: 45-70 cGy (Eq 524-815 cGy); and (3) Median dose: 29-47 cGy (337-547 cGy) for total primary breast dose of 42.5 Gy in 16 equal fractions. The spearman rho correlation showed statistical significance between the contralateral breast volume and maximum dose (P = 0.0292), as well as mean dose (P = 0.0025) and median dose (P = 0.046) to the breast. CONCLUSION: Minimizing the dose to the contralateral breast has to be one of the priorities of the radiation oncologist when using short schedules because of the radiosensitivity of this organ at risk. Further study is necessary to assess the long-term clinical impact of this schedule. PMID:22013502

  2. Dosimetric characteristics of fabricated silica fibre for postal radiotherapy dose audits

    NASA Astrophysics Data System (ADS)

    Fadzil, M. S. Ahmad; Ramli, N. N. H.; Jusoh, M. A.; Kadni, T.; Bradley, D. A.; Ung, N. M.; Suhairul, H.; Mohd Noor, N.

    2014-11-01

    Present investigation aims to establish the dosimetric characteristics of a novel fabricated flat fibre TLD system for postal radiotherapy dose audits. Various thermoluminescence (TL) properties have been investigated for five sizes of 6 mol% Ge-doped optical fibres. Key dosimetric characteristics including reproducibility, linearity, fading and energy dependence have been established. Irradiations were carried out using a linear accelerator (linac) and a Cobalt-60 machine. For doses from 0.5 Gy up to 10 Gy, Ge-doped flat fibres exhibit linearity between TL yield and dose, reproducible to better than 8% standard deviation (SD) following repeat measurements (n = 3). For photons generated at potentials from 1.25 MeV to 10 MV an energy-dependent response is noted, with a coefficient of variation (CV) of less than 40% over the range of energies investigated. For 6.0 mm length flat fibres 100 μm thick × 350 pm wide, the TL fading loss following 30 days of storage at room temperature was < 8%. The Ge-doped flat fibre system represents a viable basis for use in postal radiotherapy dose audits, corrections being made for the various factors influencing the TL yield.

  3. Enhanced epidermal dose caused by localized electron contamination from lead cutouts used in kilovoltage radiotherapy

    SciTech Connect

    Lye, J. E.; Butler, D. J.; Webb, D. V.

    2010-08-15

    Purpose: To investigate and quantify electron contamination from the lead cutouts used in kilovoltage x-ray radiotherapy. Methods: The lead cutouts were modeled with the Monte Carlo EGSnrc user codes DOSXYZnrc and DOSRZnrc for x-ray beams ranging from 50 to 300 kV{sub p}. The results from the model were confirmed with Gafchromic film measurements. The model and measurements investigated the dose distribution with and without gladwrap shielding under the lead, and dose distributions with round, square, and serrated edge cutouts. Results: Large dose enhancement near the edges of the lead was observed due to electron contamination. At the epidermal/dermal border, there is double the dose at the edge of the lead compared to the central dose due to electron contamination for a 150 kV{sub p} beam and three times the dose for a 300 kV{sub p} beam. gladwrap shielding effectively removes the contaminant dose enhancement using ten and four layers for 300 and 150 kV{sub p} beams, respectively. Conclusions: The contaminant dose enhancement is undesirable as it could cause unnecessary erythema and hyperpigmentation at the border of the treated and untreated skin and lead to a poorer cosmetic outcome. The contamination is easily removed by gladwrap shielding placed under or around the lead cutout.

  4. Estimation of Delivered Dose in Radiotherapy: The Influence of Registration Uncertainty

    PubMed Central

    Risholm, Petter; Balter, James; Wells, William M.

    2012-01-01

    We present a probabilistic framework to estimate the accumulated radiation dose and the corresponding dose uncertainty that is delivered to important anatomical structures, e.g. the primary tumor and healthy surrounding organs, during radiotherapy. The dose uncertainty we report is a direct result of uncertainties in the estimates of the deformation which aligns the daily cone-beam CT images with the planning CT. The accumulated radiation dose is an important measure to monitor during treatment, in particular to see if it significantly deviates from the planned dose which might indicate that either the patient was not properly positioned before treatment or that the anatomy has changed due to the treatment. In the case of the latter, the treatment plan should be adaptively changed to align with the current patient anatomy. We estimate the accumulated dose distribution, and its uncertainty, retrospectively on a dataset acquired during treatment of cancer in the neck and show the dose distributions in the form of dose volume histograms. PMID:22003661

  5. Dosimetric impact of setup errors in head and neck cancer patients treated by image-guided radiotherapy

    PubMed Central

    Kaur, Inderjit; Rawat, Sheh; Ahlawat, Parveen; Kakria, Anjali; Gupta, Gourav; Saxena, Upasna; Mishra, Manindra Bhushan

    2016-01-01

    To assess and analyze the impact of setup uncertainties on target volume coverage and doses to organs at risk (OAR) in head and neck cancer (HNC) patients treated by image-guided radiotherapy (IGRT). Translational setup errors in 25 HNC patients were observed by kilovoltage cone beam computed tomography (kV CBCT). Two plans were generated. Plan one – the original plan which was the initially optimized and approved plan of the patient. All patients were treated according to their respective approved plans at a defined isocenter. Plan two – the plan sum which was the sum of all plans recalculated at a different isocenter according to setup errors in x, y, and z-direction. Plan sum was created to evaluate doses that would have been received by planning target volume (PTV) and OARs if setup errors were not corrected. These 2 plans were analyzed and compared in terms of target volume coverage and doses to OARs. A total 503 kV CBCT images were acquired for evaluation of setup errors in 25 HNC patients. The systematic (mean) and random errors (standard deviation) combined for 25 patients in x, y, and z directions were 0.15 cm, 0.21 cm, and 0.19 cm and 0.09 cm, 0.12 cm, and 0.09 cm, respectively. The study showed that there was a significant difference in PTV coverage between 2 plans. The doses to various OARs showed a nonsignificant increase in the plan sum. The correction of translational setup errors is essential for IGRT treatment in terms of delivery of planned optimal doses to target volume. PMID:27217627

  6. The Impact of Dose Escalation on Secondary Cancer Risk After Radiotherapy of Prostate Cancer

    SciTech Connect

    Schneider, Uwe . E-mail: uwe.schneider@psi.ch; Lomax, Antony; Besserer, Juergen; Pemler, Peter; Lombriser, Norbert; Kaser-Hotz, Barbara D.V.M.

    2007-07-01

    Purpose: To estimate secondary cancer risk due to dose escalation in patients treated for prostatic carcinoma with three-dimensional conformal radiotherapy (3D-CRT), intensity-modulated RT (IMRT), and spot-scanned proton RT. Methods and Materials: The organ equivalent dose (OED) concept with a linear-exponential, a plateau, and a linear dose-response curve was applied to dose distributions of 23 patients who received RT of prostate cancer. Conformal RT was used in 7 patients, 8 patients received IMRT with 6- and 15-MV photons, and 8 patients were treated with spot-scanned protons. We applied target doses ranging from 70 Gy to 100 Gy. Cancer risk was estimated as a function of target dose and tumor control probability. Results: At a 100-Gy target dose the secondary cancer risk relative to the 3D treatment plan at 70 Gy was +18.4% (15.0% for a plateau model, 22.3% for a linear model) for the 6-MV IMRT plan, +25.3% (17.0%, 14.1%) for the 15-MV IMRT plan, and -40.7% (-41.3%, -40.0%) for the spot-scanned protons. The increasing risk of developing a radiation-associated malignancy after RT with increasing dose was balanced by the enhanced cure rates at a larger dose. Conclusions: Cancer risk after dose escalation for prostate RT is expected to be equal to or lower than for conventional 3D treatment at 70 Gy, independent of treatment modality or dose-response model. Spot-scanned protons are the treatment of choice for dose escalation because this therapy can halve the risk of secondary cancers.

  7. Radiotherapy planning for glioblastoma based on a tumor growth model: implications for spatial dose redistribution

    NASA Astrophysics Data System (ADS)

    Unkelbach, Jan; Menze, Bjoern H.; Konukoglu, Ender; Dittmann, Florian; Ayache, Nicholas; Shih, Helen A.

    2014-02-01

    Gliomas differ from many other tumors as they grow infiltratively into the brain parenchyma rather than forming a solid tumor mass with a well-defined boundary. Tumor cells can be found several centimeters away from the central tumor mass that is visible using current imaging techniques. The infiltrative growth characteristics of gliomas question the concept of a radiotherapy target volume that is irradiated to a homogeneous dose—the standard in current clinical practice. We discuss the use of the Fisher-Kolmogorov glioma growth model in radiotherapy treatment planning. The phenomenological tumor growth model assumes that tumor cells proliferate locally and migrate into neighboring brain tissue, which is mathematically described via a partial differential equation for the spatio-temporal evolution of the tumor cell density. In this model, the tumor cell density drops approximately exponentially with distance from the visible gross tumor volume, which is quantified by the infiltration length, a parameter describing the distance at which the tumor cell density drops by a factor of e. This paper discusses the implications for the prescribed dose distribution in the periphery of the tumor. In the context of the exponential cell kill model, an exponential fall-off of the cell density suggests a linear fall-off of the prescription dose with distance. We introduce the dose fall-off rate, which quantifies the steepness of the prescription dose fall-off in units of Gy mm-1. It is shown that the dose fall-off rate is given by the inverse of the product of radiosensitivity and infiltration length. For an infiltration length of 3 mm and a surviving fraction of 50% at 2 Gy, this suggests a dose fall-off of approximately 1 Gy mm-1. The concept is illustrated for two glioblastoma patients by optimizing intensity-modulated radiotherapy plans. The dose fall-off rate concept reflects the idea that infiltrating gliomas lack a defined boundary and are characterized by a continuous

  8. SU-E-J-14: A Novel Approach to Evaluate the Dosimetric Effect of Rectal Variation During Image Guided Prostate Radiotherapy

    SciTech Connect

    Murray, J; McQuaid, D; Dunlop, A; Nill, S; Gulliford, S; Buettner, F; Hall, E; Dearnaley, D

    2014-06-01

    Purpose: Deformable registration establishes the spatial correspondence back to the reference image in order to accumulate dose. However, in prostate radiotherapy the changing shape and volume of the rectum present a challenge to accurate deformable registration and consequently calculation of delivered dose. We explored an alternative approach to calculating accumulated dose to the rectum, independent of deformable registration. Methods: This study was performed on three patients who received online image-guided radiotherapy (IGRT) with daily CBCT (XVI-system,Elekta) and target localization using intraprostatic fiducials. On each CBCT, the rectum was manually contoured and bulk density assignments were made allowing dose to be calculated for each fraction. Dose-surface maps (DSM) were generated (MATLAB,Mathworks,Natick,MA) by considering the rectum as a cylinder and sampling the dose at 21-equispaced points on each CT slice. The cylinder was “cut” at the posterior-most position on each CT and unfolded to generate a DSM. These were normalised in the longitudinal direction by interpolation creating maps of 21×21 pixels. A DSM was produced for each CBCT and the dose was accumulated. Results: The mean accumulated delivered rectal surface dose was on average 7.5(+/−3.5)% lower than the planned dose. The dose difference maps consistently show that the greatest variation in dose between planned and delivered dose is away from where the rectal surface is adjacent to the prostate. Conclusion: Estimation of dose accumulation using DSM provides an alternative method for determining actual delivered dose to the rectum. The dose difference is greatest in areas away from the region where the rectal surface abuts the prostate, the region where set-up is verified. The change in size and shape of the rectum was shown to resultin a change in the accumulated dose compared to the planned dose and this will have an impact on determining the relationships between dose delivered

  9. Dose verification of radiotherapy for lung cancer by using plastic scintillator dosimetry and a heterogeneous phantom

    NASA Astrophysics Data System (ADS)

    Ottosson, W.; Behrens, C. F.; Andersen, C. E.

    2015-01-01

    Bone, air passages, cavities, and lung are elements present in patients, but challenging to properly correct for in treatment planning dose calculations. Plastic scintillator detectors (PSDs) have proven to be well suited for dosimetry in non-reference conditions such as small fields. The objective of this study was to investigate the performance of a commercial treatment planning system (TPS) using a PSD and a specially designed thorax phantom with lung tumor inserts. 10 treatment plans of different complexity and phantom configurations were evaluated. Although the TPS agreed well with the measurements for the least complex tests, deviations of tumor dose > 4% were observed for some cases. This study underpins the dosimetric challenge in TPS calculations for clinically relevant heterogeneous geometries. The scintillator system, together with the special phantom, provides a promising tool for evaluation of complex radiotherapy dose calculations and delivery.

  10. Evaluation of doses in radiotherapy using solid-state composites based on natural colourless topaz.

    PubMed

    Souza, Divanizia N; Meira, Reges A; Lima, José F; Valerio, Mário Ernesto G; Caldas, Linda V E

    2003-04-01

    The thermoluminescent properties of composites containing powdered topaz embedded in Teflon or glass were studied and compared with the corresponding properties of the well known TLD-100 commercial dosimeters. Relative sensitivity, TL fading, reproducibility of the sample preparation process, and possibility of re-utilisation of the dosimeters were investigated. Measurements of absorbed doses in simulated radiotherapy treatments were also taken. The irradiations were performed using gamma rays from a 60Co source in the dose range from 1cGy to 2Gy. The dosimeters were installed in badges and attached inside acrylic plates of various thicknesses in the radiation fields. The dose profiles obtained with this procedure are very similar to the ones obtained with equivalent tissues. It is concluded that these composites of natural colourless topaz crystals can be efficiently used as TL dosimeters. PMID:12672629

  11. Evaluation of nonrigid registration models for interfraction dose accumulation in radiotherapy

    SciTech Connect

    Janssens, Guillaume; Orban de Xivry, Jonathan; Fekkes, Stein; Dekker, Andre; Macq, Benoit; Lambin, Philippe; Elmpt, Wouter van

    2009-09-15

    and an overdosed bladder volume due to anatomical deformations. Conclusions: Dose accumulation using nonrigid registration methods is possible using repeated CT imaging. This opens possibilities for interfraction dose accumulation and adaptive radiotherapy to incorporate possible differences in dose delivered to the target volume and organs at risk due to anatomical deformations.

  12. Fast dose algorithm for generation of dose coverage probability for robustness analysis of fractionated radiotherapy

    NASA Astrophysics Data System (ADS)

    Tilly, David; Ahnesjö, Anders

    2015-07-01

    A fast algorithm is constructed to facilitate dose calculation for a large number of randomly sampled treatment scenarios, each representing a possible realisation of a full treatment with geometric, fraction specific displacements for an arbitrary number of fractions. The algorithm is applied to construct a dose volume coverage probability map (DVCM) based on dose calculated for several hundred treatment scenarios to enable the probabilistic evaluation of a treatment plan. For each treatment scenario, the algorithm calculates the total dose by perturbing a pre-calculated dose, separately for the primary and scatter dose components, for the nominal conditions. The ratio of the scenario specific accumulated fluence, and the average fluence for an infinite number of fractions is used to perturb the pre-calculated dose. Irregularities in the accumulated fluence may cause numerical instabilities in the ratio, which is mitigated by regularisation through convolution with a dose pencil kernel. Compared to full dose calculations the algorithm demonstrates a speedup factor of ~1000. The comparisons to full calculations show a 99% gamma index (2%/2 mm) pass rate for a single highly modulated beam in a virtual water phantom subject to setup errors during five fractions. The gamma comparison shows a 100% pass rate in a moving tumour irradiated by a single beam in a lung-like virtual phantom. DVCM iso-probability lines computed with the fast algorithm, and with full dose calculation for each of the fractions, for a hypo-fractionated prostate case treated with rotational arc therapy treatment were almost indistinguishable.

  13. Fast dose algorithm for generation of dose coverage probability for robustness analysis of fractionated radiotherapy.

    PubMed

    Tilly, David; Ahnesjö, Anders

    2015-07-21

    A fast algorithm is constructed to facilitate dose calculation for a large number of randomly sampled treatment scenarios, each representing a possible realisation of a full treatment with geometric, fraction specific displacements for an arbitrary number of fractions. The algorithm is applied to construct a dose volume coverage probability map (DVCM) based on dose calculated for several hundred treatment scenarios to enable the probabilistic evaluation of a treatment plan.For each treatment scenario, the algorithm calculates the total dose by perturbing a pre-calculated dose, separately for the primary and scatter dose components, for the nominal conditions. The ratio of the scenario specific accumulated fluence, and the average fluence for an infinite number of fractions is used to perturb the pre-calculated dose. Irregularities in the accumulated fluence may cause numerical instabilities in the ratio, which is mitigated by regularisation through convolution with a dose pencil kernel.Compared to full dose calculations the algorithm demonstrates a speedup factor of ~1000. The comparisons to full calculations show a 99% gamma index (2%/2 mm) pass rate for a single highly modulated beam in a virtual water phantom subject to setup errors during five fractions. The gamma comparison shows a 100% pass rate in a moving tumour irradiated by a single beam in a lung-like virtual phantom. DVCM iso-probability lines computed with the fast algorithm, and with full dose calculation for each of the fractions, for a hypo-fractionated prostate case treated with rotational arc therapy treatment were almost indistinguishable. PMID:26118844

  14. On-line MR imaging for dose validation of abdominal radiotherapy.

    PubMed

    Glitzner, M; Crijns, S P M; de Senneville, B Denis; Kontaxis, C; Prins, F M; Lagendijk, J J W; Raaymakers, B W

    2015-11-21

    For quality assurance and adaptive radiotherapy, validation of the actual delivered dose is crucial.Intrafractional anatomy changes cannot be captured satisfactorily during treatment with hitherto available imaging modalitites. Consequently, dose calculations are based on the assumption of static anatomy throughout the treatment. However, intra- and interfraction anatomy is dynamic and changes can be significant.In this paper, we investigate the use of an MR-linac as a dose tracking modality for the validation of treatments in abdominal targets where both respiratory and long-term peristaltic and drift motion occur.The on-line MR imaging capability of the modality provides the means to perform respiratory gating of both delivery and acquisition yielding a model-free respiratory motion management under free breathing conditions.In parallel to the treatment, the volumetric patient anatomy was captured and used to calculate the applied dose. Subsequently, the individual doses were warped back to the planning grid to obtain the actual dose accumulated over the entire treatment duration. Ultimately, the planned dose was validated by comparison with the accumulated dose.Representative for a site subject to breathing modulation, two kidney cases (25 Gy target dose) demonstrated the working principle on volunteer data and simulated delivery. The proposed workflow successfully showed its ability to track local dosimetric changes. Integration of the on-line anatomy information could reveal local dose variations  -2.3-1.5 Gy in the target volume of a volunteer dataset. In the adjacent organs at risk, high local dose errors ranging from  -2.5 to 1.9 Gy could be traced back. PMID:26531846

  15. Patient doses in {gamma}-intracoronary radiotherapy: The Radiation Burden Assessment Study

    SciTech Connect

    Thierens, Hubert . E-mail: hubert.thierens@Ughent.be; Reynaert, Nick; Bacher, Klaus; Eijkeren, Marc van; Taeymans, Yves

    2004-10-01

    Purpose: To determine accurately the radiation burden of both patients and staff from intracoronary radiotherapy (IRT) with {sup 192}Ir and to investigate the importance of IRT in the patient dose compared with interventional X-rays. Methods and materials: The Radiation Burden Assessment Study (RABAS) population consisted of 9 patients undergoing {gamma}-IRT after percutaneous transluminal coronary angioplasty and 14 patients undergoing percutaneous transluminal coronary angioplasty only as the control group. For each patient, the dose to the organs and tissues from the internal and external exposure was determined in detail by Monte Carlo N-particle simulations. Patient skin dose measurements with thermoluminescence dosimeters served as verification. Staff dosimetry was performed with electronic dosimeters, thermoluminescence dosimeters, and double film badge dosimetry. Results: With respect to the patient dose from IRT, the critical organs are the thymus (58 mGy), lungs (31 mGy), and esophagus (27 mGy). The mean effective dose from IRT was 8 mSv. The effective dose values from interventional X-rays showed a broad range (2-28 mSv), with mean values of 8 mSv for the IRT patients and 13 mSv for the control group. The mean dose received by the radiotherapist from IRT was 4 {mu}Sv/treatment. The doses to the other staff members were completely negligible. Conclusion: Our results have shown that the patient and personnel doses in {gamma}-IRT remain at an acceptable level. The patient dose from IRT was within the variations in dose from the accompanying interventional X-rays.

  16. On-line MR imaging for dose validation of abdominal radiotherapy

    NASA Astrophysics Data System (ADS)

    Glitzner, M.; Crijns, S. P. M.; de Senneville, B. Denis; Kontaxis, C.; Prins, F. M.; Lagendijk, J. J. W.; Raaymakers, B. W.

    2015-11-01

    For quality assurance and adaptive radiotherapy, validation of the actual delivered dose is crucial. Intrafractional anatomy changes cannot be captured satisfactorily during treatment with hitherto available imaging modalitites. Consequently, dose calculations are based on the assumption of static anatomy throughout the treatment. However, intra- and interfraction anatomy is dynamic and changes can be significant. In this paper, we investigate the use of an MR-linac as a dose tracking modality for the validation of treatments in abdominal targets where both respiratory and long-term peristaltic and drift motion occur. The on-line MR imaging capability of the modality provides the means to perform respiratory gating of both delivery and acquisition yielding a model-free respiratory motion management under free breathing conditions. In parallel to the treatment, the volumetric patient anatomy was captured and used to calculate the applied dose. Subsequently, the individual doses were warped back to the planning grid to obtain the actual dose accumulated over the entire treatment duration. Ultimately, the planned dose was validated by comparison with the accumulated dose. Representative for a site subject to breathing modulation, two kidney cases (25 Gy target dose) demonstrated the working principle on volunteer data and simulated delivery. The proposed workflow successfully showed its ability to track local dosimetric changes. Integration of the on-line anatomy information could reveal local dose variations  -2.3-1.5 Gy in the target volume of a volunteer dataset. In the adjacent organs at risk, high local dose errors ranging from  -2.5 to 1.9 Gy could be traced back.

  17. Megavoltage cone beam CT near surface dose measurements: potential implications for breast radiotherapy

    SciTech Connect

    Quinn, Alexandra; Holloway, Lois; Cutajar, Dean; Hardcastle, Nicholas; Rosenfeld, Anatoly; Metcalfe, Peter

    2011-11-15

    Purpose: Cone beam computed tomography (CBCT) is fast becoming standard on modern linear accelerators. CBCT increases the dose to regions within and outside the treatment field, potentially increasing secondary cancer induction and toxicity. This study quantified megavoltage (MV) CBCT skin dose and compared it to skin dose delivered during standard tangential breast radiotherapy.Method: Dosimetry was performed both in- and out-of-field using thermoluminescent dosimeters (TLDs) and a metal-oxide-semiconductor-field-effect-transistor (MOSFET) detector specifically designed for skin dosimetry; these were placed superficially on a female anthropomorphic phantom. Results: The skin dose from a single treatment fraction ranged from 0.5 to 1.4 Gy on the ipsilateral breast, 0.031-0.18 Gy on the contralateral breast, and 0-0.02 Gy in the head and pelvic region. An 8 MU MV CBCT delivered a skin dose that ranged from 0.02 to 0.05 Gy in the chest region and was less than 0.01 Gy in the head and pelvis regions. One MV CBCT per fraction was found to increase the out-of-field skin dose from both the CBCT and the treatment fields by approximately 20%. The imaging dose as a percentage of treatment doses in the ipsilateral breast region was 3% for both dosimeters.Conclusion: Imaging increases the skin dose to regions outside the treatment field particularly regions immediately adjacent the target volume. This small extra dose to the breasts should be considered when developing clinical protocols and assessing dose for clinical trials.

  18. Quality assurance for radiotherapy in prostate cancer: Point dose measurements in intensity modulated fields with large dose gradients

    SciTech Connect

    Escude, Lluis . E-mail: lluis.escude@gmx.net; Linero, Dolors; Molla, Meritxell; Miralbell, Raymond

    2006-11-15

    Purpose: We aimed to evaluate an optimization algorithm designed to find the most favorable points to position an ionization chamber (IC) for quality assurance dose measurements of patients treated for prostate cancer with intensity-modulated radiotherapy (IMRT) and fields up to 10 cm x 10 cm. Methods and Materials: Three cylindrical ICs (PTW, Freiburg, Germany) were used with volumes of 0.6 cc, 0.125 cc, and 0.015 cc. Dose measurements were made in a plastic phantom (PMMA) at 287 optimized points. An algorithm was designed to search for points with the lowest dose gradient. Measurements were made also at 39 nonoptimized points. Results were normalized to a reference homogeneous field introducing a dose ratio factor, which allowed us to compare measured vs. calculated values as percentile dose ratio factor deviations {delta}F (%). A tolerance range of {delta}F (%) of {+-}3% was considered. Results: Half of the {delta}F (%) values obtained at nonoptimized points were outside the acceptable range. Values at optimized points were widely spread for the largest IC (i.e., 60% of the results outside the tolerance range), whereas for the two small-volume ICs, only 14.6% of the results were outside the tolerance interval. No differences were observed when comparing the two small ICs. Conclusions: The presented optimization algorithm is a useful tool to determine the best IC in-field position for optimal dose measurement conditions. A good agreement between calculated and measured doses can be obtained by positioning small volume chambers at carefully selected points in the field. Large chambers may be unreliable even in optimized points for IMRT fields {<=}10 cm x 10 cm.

  19. Validation of fast Monte Carlo dose calculation in small animal radiotherapy with EBT3 radiochromic films.

    PubMed

    Noblet, C; Chiavassa, S; Smekens, F; Sarrut, D; Passal, V; Suhard, J; Lisbona, A; Paris, F; Delpon, G

    2016-05-01

    In preclinical studies, the absorbed dose calculation accuracy in small animals is fundamental to reliably investigate and understand observed biological effects. This work investigated the use of the split exponential track length estimator (seTLE), a new kerma based Monte Carlo dose calculation method for preclinical radiotherapy using a small animal precision micro irradiator, the X-RAD 225Cx. Monte Carlo modelling of the irradiator with GATE/GEANT4 was extensively evaluated by comparing measurements and simulations for half-value layer, percent depth dose, off-axis profiles and output factors in water and water-equivalent material for seven circular fields, from 20 mm down to 1 mm in diameter. Simulated and measured dose distributions in cylinders of water obtained for a 360° arc were also compared using dose, distance-to-agreement and gamma-index maps. Simulations and measurements agreed within 3% for all static beam configurations, with uncertainties estimated to 1% for the simulation and 3% for the measurements. Distance-to-agreement accuracy was better to 0.14 mm. For the arc irradiations, gamma-index maps of 2D dose distributions showed that the success rate was higher than 98%, except for the 0.1 cm collimator (92%). Using the seTLE method, MC simulations compute 3D dose distributions within minutes for realistic beam configurations with a clinically acceptable accuracy for beam diameter as small as 1 mm. PMID:27055114

  20. Evaluation of target dose based on water-equivalent thickness in external beam radiotherapy

    PubMed Central

    Moghaddam, Behnaz Ghanbar; Vahabi-Moghaddam, Masoud; Sadremomtaz, Alireza

    2013-01-01

    In vivo dosimetry was carried out for 152 patients receiving external beam radiotherapy and the treatment sites were divided into two main groups: Thorax, Abdomen, and Pelvic (120 fields) and Head and Neck (52 fields). Combined entrance and exit dose measurements were performed using LiF: Mg, Cu, P thermoluminescent dosimeters (TLDs). Water-equivalent (effective) thicknesses and target dose were evaluated using dose transmission data. The ratio of measured to expected value for each quantity was considered as an indicator for the accuracy of the parameter. The average ratio of the entrance dose was evaluated as 1.01 ± 0.07. In the diameter measurement, the mean ratio of effective depth divided by the contour depth is 1.00 ± 0.13 that shows a wide distribution which reflects the influence of contour inaccuracies as well as tissue inhomogeneities. At the target level, the mean ratio of measured to the prescribed dose is 1.00 ± 0.07. According to our findings, the difference between effective depth and patient depth has a direct relation to target dose discrepancies. There are some inevitable sources which may cause the difference. Evaluation and application of effective diameter in treatment calculations would lead to a more reliable target dose, especially for fields which involve Thorax, Abdomen, and Pelvic. PMID:23532059

  1. Validation of fast Monte Carlo dose calculation in small animal radiotherapy with EBT3 radiochromic films

    NASA Astrophysics Data System (ADS)

    Noblet, C.; Chiavassa, S.; Smekens, F.; Sarrut, D.; Passal, V.; Suhard, J.; Lisbona, A.; Paris, F.; Delpon, G.

    2016-05-01

    In preclinical studies, the absorbed dose calculation accuracy in small animals is fundamental to reliably investigate and understand observed biological effects. This work investigated the use of the split exponential track length estimator (seTLE), a new kerma based Monte Carlo dose calculation method for preclinical radiotherapy using a small animal precision micro irradiator, the X-RAD 225Cx. Monte Carlo modelling of the irradiator with GATE/GEANT4 was extensively evaluated by comparing measurements and simulations for half-value layer, percent depth dose, off-axis profiles and output factors in water and water-equivalent material for seven circular fields, from 20 mm down to 1 mm in diameter. Simulated and measured dose distributions in cylinders of water obtained for a 360° arc were also compared using dose, distance-to-agreement and gamma-index maps. Simulations and measurements agreed within 3% for all static beam configurations, with uncertainties estimated to 1% for the simulation and 3% for the measurements. Distance-to-agreement accuracy was better to 0.14 mm. For the arc irradiations, gamma-index maps of 2D dose distributions showed that the success rate was higher than 98%, except for the 0.1 cm collimator (92%). Using the seTLE method, MC simulations compute 3D dose distributions within minutes for realistic beam configurations with a clinically acceptable accuracy for beam diameter as small as 1 mm.

  2. Effect of Tissue Composition on Dose Distribution in Electron Beam Radiotherapy

    PubMed Central

    Ghorbani, M.; Tabatabaei, Z. S.; Vejdani Noghreiyan, A.; Vosoughi, H.; Knaup, C.

    2015-01-01

    Objective The aim of this study is to evaluate the effect of tissue composition on dose distribution in electron beam radiotherapy. Methods A Siemens Primus linear accelerator and a phantom were simulated using MCNPX Monte Carlo code. In a homogeneous cylindrical phantom, six types of soft tissue and three types of tissue-equivalent materials were investigated. The tissues included muscle (skeletal), adipose tissue, blood (whole), breast tissue, soft tissue (9-components) and soft tissue (4-component). The tissue-equivalent materials were water, A-150 tissue-equivalent plastic and perspex. Electron dose relative to dose in 9-component soft tissue at various depths on the beam’s central axis was determined for 8, 12, and 14 MeV electron energies. Results The results of relative electron dose in various materials relative to dose in 9-component soft tissue were reported for 8, 12 and 14 MeV electron beams as tabulated data. While differences were observed between dose distributions in various soft tissues and tissue-equivalent materials, which vary with the composition of material, electron energy and depth in phantom, they can be ignored due to the incorporated uncertainties in Monte Carlo calculations. Conclusion Based on the calculations performed, differences in dose distributions in various soft tissues and tissue-equivalent materials are not significant. However, due to the difference in composition of various materials, further research in this field with lower uncertainties is recommended. PMID:25973407

  3. Intensity-Modulated Radiotherapy for Craniospinal Irradiation: Target Volume Considerations, Dose Constraints, and Competing Risks

    SciTech Connect

    Parker, William Filion, Edith; Roberge, David; Freeman, Carolyn R.

    2007-09-01

    Purpose: To report the results of an analysis of dose received to tissues and organs outside the target volume, in the setting of spinal axis irradiation for the treatment of medulloblastoma, using three treatment techniques. Methods and Materials: Treatment plans (total dose, 23.4 Gy) for a standard two-dimensional (2D) technique, a three-dimensional (3D) technique using a 3D imaging-based target volume, and an intensity-modulated radiotherapy (IMRT) technique, were compared for 3 patients in terms of dose-volume statistics for target coverage, as well as organ at risk (OAR) and overall tissue sparing. Results: Planning target volume coverage and dose homogeneity was superior for the IMRT plans for V{sub 95%} (IMRT, 100%; 3D, 96%; 2D, 98%) and V{sub 107%} (IMRT, 3%; 3D, 38%; 2D, 37%). In terms of OAR sparing, the IMRT plan was better for all organs and whole-body contour when comparing V{sub 10Gy}, V{sub 15Gy}, and V{sub 20Gy}. The 3D plan was superior for V{sub 5Gy} and below. For the heart and liver in particular, the IMRT plans provided considerable sparing in terms of V{sub 10Gy} and above. In terms of the integral dose, the IMRT plans were superior for liver (IMRT, 21.9 J; 3D, 28.6 J; 2D, 38.6 J) and heart (IMRT, 9 J; 3D, 14.1J; 2D, 19.4 J), the 3D plan for the body contour (IMRT, 349 J; 3D, 337 J; 2D, 555 J). Conclusions: Intensity-modulated radiotherapy is a valid treatment option for spinal axis irradiation. We have shown that IMRT results in sparing of organs at risk without a significant increase in integral dose.

  4. Impact of Dose on Local Failure Rates After Image-Guided Reirradiation of Recurrent Paraspinal Metastases

    SciTech Connect

    Damast, Shari; Wright, Jean; Bilsky, Mark; Hsu, Meier; Zhang Zhigang; Lovelock, Michael; Cox, Brett; Zatcky, Joan; Yamada, Yoshiya

    2011-11-01

    Purpose: To examine the impact of dose on local failure (LF) rates in the re-treatment of recurrent paraspinal metastases with image-guided intensity-modulated radiotherapy (IG-IMRT). Methods and Materials: The records of patients with in-field recurrence after previous spine radiation (median dose, 30 Gy) who received salvage IG-IMRT with either five 4-Gy (20-Gy group, n = 42) or five 6-Gy (30-Gy group, n = 55) daily fractions between January 2003 and August 2008 were reviewed. Institutional practice was 20 Gy before April 2006, when it changed to 30 Gy. A total of 47 cases (48%) were treated adjuvantly, after surgery to decompress epidural disease. LF after IG-IMRT was defined radiographically. Results: The median follow-up was 12.1 months (range, 0.2-63.6 months). The 1-year cumulative incidences of LF after 20 Gy and 30 Gy IG-IMRT were 45% and 26%, respectively (p = 0.04). Of all treatment characteristics examined (20-Gy vs. 30-Gy dose group, dose to 95% of the planned and gross target volume, tumor size, histology, receipt of surgery, and interval between first and second radiation), only dose group had a significant impact on actuarial LF incidence (p = 0.04; unadjusted HR, 0.51; 95% CI, 0.27-0.96). There was no incidence of myelopathy. Conclusions: A significant decrease in LF after IG-IMRT with five 6-Gy fractions compared with five 4-Gy fractions was observed without increased risk of myelopathy. Until prospective data comparing stereotactic hypofractionated and single-fraction regimens become available, when reirradiating recurrent paraspinal metastases with IG-IMRT, administration of five 6-Gy daily fractions is reasonable.

  5. A trichrome beam model for biological dose calculation in scanned carbon-ion radiotherapy treatment planning

    NASA Astrophysics Data System (ADS)

    Inaniwa, T.; Kanematsu, N.

    2015-01-01

    In scanned carbon-ion (C-ion) radiotherapy, some primary C-ions undergo nuclear reactions before reaching the target and the resulting particles deliver doses to regions at a significant distance from the central axis of the beam. The effects of these particles on physical dose distribution are accounted for in treatment planning by representing the transverse profile of the scanned C-ion beam as the superposition of three Gaussian distributions. In the calculation of biological dose distribution, however, the radiation quality of the scanned C-ion beam has been assumed to be uniform over its cross-section, taking the average value over the plane at a given depth (monochrome model). Since these particles, which have relatively low radiation quality, spread widely compared to the primary C-ions, the radiation quality of the beam should vary with radial distance from the central beam axis. To represent its transverse distribution, we propose a trichrome beam model in which primary C-ions, heavy fragments with atomic number Z ≥ 3, and light fragments with Z ≤ 2 are assigned to the first, second, and third Gaussian components, respectively. Assuming a realistic beam-delivery system, we performed computer simulations using Geant4 Monte Carlo code for analytical beam modeling of the monochrome and trichrome models. The analytical beam models were integrated into a treatment planning system for scanned C-ion radiotherapy. A target volume of 20  ×  20  ×  40 mm3 was defined within a water phantom. A uniform biological dose of 2.65 Gy (RBE) was planned for the target with the two beam models based on the microdosimetric kinetic model (MKM). The plans were recalculated with Geant4, and the recalculated biological dose distributions were compared with the planned distributions. The mean target dose of the recalculated distribution with the monochrome model was 2.72 Gy (RBE), while the dose with the trichrome model was 2.64 Gy (RBE). The monochrome model

  6. Optimization and quality assurance of an image-guided radiation therapy system for intensity-modulated radiation therapy radiotherapy

    SciTech Connect

    Tsai, Jen-San; Micaily, Bizhan; Miyamoto, Curtis

    2012-10-01

    To develop a quality assurance (QA) of XVI cone beam system (XVIcbs) for its optimal imaging-guided radiotherapy (IGRT) implementation, and to construe prostate tumor margin required for intensity-modulated radiation therapy (IMRT) if IGRT is unavailable. XVIcbs spatial accuracy was explored with a humanoid phantom; isodose conformity to lesion target with a rice phantom housing a soap as target; image resolution with a diagnostic phantom; and exposure validation with a Radcal ion chamber. To optimize XVIcbs, rotation flexmap on coincidency between gantry rotational axis and that of XVI cone beam scan was investigated. Theoretic correlation to image quality of XVIcbs rotational axis stability was elaborately studied. Comprehensive QA of IGRT using XVIcbs has initially been explored and then implemented on our general IMRT treatments, and on special IMRT radiotherapies such as head and neck (H and N), stereotactic radiation therapy (SRT), stereotactic radiosurgery (SRS), and stereotactic body radiotherapy (SBRT). Fifteen examples of prostate setup accounted for 350 IGRT cone beam system were analyzed. IGRT accuracy results were in agreement {+-} 1 mm. Flexmap 0.25 mm met the manufacturer's specification. Films confirmed isodose coincidence with target (soap) via XVIcbs, otherwise not. Superficial doses were measured from 7.2-2.5 cGy for anatomic diameters 15-33 cm, respectively. Image quality was susceptible to rotational stability or patient movement. IGRT using XVIcbs on general IMRT treatments such as prostate, SRT, SRS, and SBRT for setup accuracy were verified; and subsequently coordinate shifts corrections were recorded. The 350 prostate IGRT coordinate shifts modeled to Gaussian distributions show central peaks deviated off the isocenter by 0.6 {+-} 3.0 mm, 0.5 {+-} 4.5 mm in the X(RL)- and Z(SI)-coordinates, respectively; and 2.0 {+-} 3.0 mm in the Y(AP)-coordinate as a result of belly and bladder capacity variations. Sixty-eight percent of confidence was

  7. SU-E-J-205: Monte Carlo Modeling of Ultrasound Probes for Real-Time Ultrasound Image-Guided Radiotherapy

    SciTech Connect

    Hristov, D; Schlosser, J; Bazalova, M; Chen, J

    2014-06-01

    Purpose: To quantify the effect of ultrasound (US) probe beam attenuation for radiation therapy delivered under real-time US image guidance by means of Monte Carlo (MC) simulations. Methods: MC models of two Philips US probes, an X6-1 matrix-array transducer and a C5-2 curved-array transducer, were built based on their CT images in the EGSnrc BEAMnrc and DOSXYZnrc codes. Due to the metal parts, the probes were scanned in a Tomotherapy machine with a 3.5 MV beam. Mass densities in the probes were assigned based on an electron density calibration phantom consisting of cylinders with mass densities between 0.2–8.0 g/cm{sup 3}. Beam attenuation due to the probes was measured in a solid water phantom for a 6 MV and 15 MV 15x15 cm{sup 2} beam delivered on a Varian Trilogy linear accelerator. The dose was measured with the PTW-729 ionization chamber array at two depths and compared to MC simulations. The extreme case beam attenuation expected in robotic US image guided radiotherapy for probes in upright position was quantified by means of MC simulations. Results: The 3.5 MV CT number to mass density calibration curve was found to be linear with R{sup 2} > 0.99. The maximum mass densities were 4.6 and 4.2 g/cm{sup 3} in the C5-2 and X6-1 probe, respectively. Gamma analysis of the simulated and measured doses revealed that over 98% of measurement points passed the 3%/3mm criteria for both probes and measurement depths. The extreme attenuation for probes in upright position was found to be 25% and 31% for the C5-2 and X6-1 probe, respectively, for both 6 and 15 MV beams at 10 cm depth. Conclusion: MC models of two US probes used for real-time image guidance during radiotherapy have been built. As a Result, radiotherapy treatment planning with the imaging probes in place can now be performed. J Schlosser is an employee of SoniTrack Systems, Inc. D Hristov has financial interest in SoniTrack Systems, Inc.

  8. High-dose simultaneously integrated breast boost using intensity-modulated radiotherapy and inverse optimization

    SciTech Connect

    Hurkmans, Coen W. . E-mail: coen.hurkmans@cze.nl; Meijer, Gert J.; Vliet-Vroegindeweij, Corine van; Cassee, Jorien

    2006-11-01

    Purpose: Recently a Phase III randomized trial has started comparing a boost of 16 Gy as part of whole-breast irradiation to a high boost of 26 Gy in young women. Our main aim was to develop an efficient simultaneously integrated boost (SIB) technique for the high-dose arm of the trial. Methods and Materials: Treatment planning was performed for 5 left-sided and 5 right-sided tumors. A tangential field intensity-modulated radiotherapy technique added to a sequentially planned 3-field boost (SEQ) was compared with a simultaneously planned technique (SIB) using inverse optimization. Normalized total dose (NTD)-corrected dose volume histogram parameters were calculated and compared. Results: The intended NTD was produced by 31 fractions of 1.66 Gy to the whole breast and 2.38 Gy to the boost volume. The average volume of the PTV-breast and PTV-boost receiving more than 95% of the prescribed dose was 97% or more for both techniques. Also, the mean lung dose and mean heart dose did not differ much between the techniques, with on average 3.5 Gy and 2.6 Gy for the SEQ and 3.8 Gy and 2.6 Gy for the SIB, respectively. However, the SIB resulted in a significantly more conformal irradiation of the PTV-boost. The volume of the PTV-breast, excluding the PTV-boost, receiving a dose higher than 95% of the boost dose could be reduced considerably using the SIB as compared with the SEQ from 129 cc (range, 48-262 cc) to 58 cc (range, 30-102 cc). Conclusions: A high-dose simultaneously integrated breast boost technique has been developed. The unwanted excessive dose to the breast was significantly reduced.

  9. Pharmacodynamic imaging guides dosing of a selective estrogen receptor degrader

    PubMed Central

    Heidari, Pedram; Deng, Francis; Esfahani, Shadi A.; Leece, Alicia K.; Shoup, Timothy M.; Vasdev, Neil; Mahmood, Umar

    2015-01-01

    Purpose Estrogen receptor (ER) targeting is key in management of receptor-positive breast cancer (BrCa). Currently, there are no methods to optimize anti-ER therapy dosing. This study assesses the utility of 16α-18F-fluoroestradiol (18F-FES) PET for fulvestrant dose optimization in a preclinical ER+ BrCa model. Experimental Design In vitro, 18F-FES retention was compared to ERα protein expression (ELISA) and ESR1 mRNA transcription (qPCR) in MCF7 cells (ER+) after treatment with different fulvestrant doses. MCF7 xenografts were grown in ovariectomized nude mice and assigned to vehicle, low- (0.05mg), medium- (0.5mg) or high-dose (5mg) fulvestrant treatment groups (5–7 per group). Two and three days after fulvestrant treatment, PET/CT was performed using 18F-FES and 18F-FDG, respectively. ER expression was assessed by immunohistochemistry, ELISA, and qPCR on xenografts. Tumor proliferation was assessed using Ki-67 immunohistochemistry. Results In vitro, we observed a parallel graded reduction in 18F-FES uptake and ER expression with increased fulvestrant doses, despite enhancement of ER mRNA transcription. In xenografts, ER expression significantly decreased with increased fulvestrant dose, despite similar mRNA expression and Ki-67 staining among the treatment groups. We observed a significant dose-dependent reduction of 18F-FES PET mean standardized uptake value (SUVmean) with fulvestrant treatment, but no significant difference among the treatment groups in 18F-FDG PET SUVmean.. Conclusion We demonstrated that 18F-FES uptake mirrors the dose-dependent changes in functional ER expression with fulvestrant resulting in ER degradation and/or blockade; these precede changes in tumor metabolism and proliferation. Quantitative 18F-FES PET may be useful for tracking early efficacy of ER blockade/degradation and guiding ER-targeted therapy dosing in BrCa patients. PMID:25609068

  10. Accurate calibration of a stereo-vision system in image-guided radiotherapy.

    PubMed

    Liu, Dezhi; Li, Shidong

    2006-11-01

    Image-guided radiotherapy using a three-dimensional (3D) camera as the on-board surface imaging system requires precise and accurate registration of the 3D surface images in the treatment machine coordinate system. Two simple calibration methods, an analytical solution as three-point matching and a least-squares estimation method as multipoint registration, were introduced to correlate the stereo-vision surface imaging frame with the machine coordinate system. Both types of calibrations utilized 3D surface images of a calibration template placed on the top of the treatment couch. Image transformational parameters were derived from corresponding 3D marked points on the surface images to their given coordinates in the treatment room coordinate system. Our experimental results demonstrated that both methods had provided the desired calibration accuracy of 0.5 mm. The multipoint registration method is more robust particularly for noisy 3D surface images. Both calibration methods have been used as our weekly QA tools for a 3D image-guided radiotherapy system. PMID:17153416

  11. Accurate calibration of a stereo-vision system in image-guided radiotherapy

    SciTech Connect

    Liu Dezhi; Li Shidong

    2006-11-15

    Image-guided radiotherapy using a three-dimensional (3D) camera as the on-board surface imaging system requires precise and accurate registration of the 3D surface images in the treatment machine coordinate system. Two simple calibration methods, an analytical solution as three-point matching and a least-squares estimation method as multipoint registration, were introduced to correlate the stereo-vision surface imaging frame with the machine coordinate system. Both types of calibrations utilized 3D surface images of a calibration template placed on the top of the treatment couch. Image transformational parameters were derived from corresponding 3D marked points on the surface images to their given coordinates in the treatment room coordinate system. Our experimental results demonstrated that both methods had provided the desired calibration accuracy of 0.5 mm. The multipoint registration method is more robust particularly for noisy 3D surface images. Both calibration methods have been used as our weekly QA tools for a 3D image-guided radiotherapy system.

  12. Radiation dose verification using real tissue phantom in modern radiotherapy techniques

    PubMed Central

    Gurjar, Om Prakash; Mishra, S. P.; Bhandari, Virendra; Pathak, Pankaj; Patel, Prapti; Shrivastav, Garima

    2014-01-01

    In vitro dosimetric verification prior to patient treatment has a key role in accurate and precision radiotherapy treatment delivery. Most of commercially available dosimetric phantoms have almost homogeneous density throughout their volume, while real interior of patient body has variable and varying densities inside. In this study an attempt has been made to verify the physical dosimetry in actual human body scenario by using goat head as “head phantom” and goat meat as “tissue phantom”. The mean percentage variation between planned and measured doses was found to be 2.48 (standard deviation (SD): 0.74), 2.36 (SD: 0.77), 3.62 (SD: 1.05), and 3.31 (SD: 0.78) for three-dimensional conformal radiotherapy (3DCRT) (head phantom), intensity modulated radiotherapy (IMRT; head phantom), 3DCRT (tissue phantom), and IMRT (tissue phantom), respectively. Although percentage variations in case of head phantom were within tolerance limit (< ± 3%), but still it is higher than the results obtained by using commercially available phantoms. And the percentage variations in most of cases of tissue phantom were out of tolerance limit. On the basis of these preliminary results it is logical and rational to develop radiation dosimetry methods based on real human body and also to develop an artificial phantom which should truly represent the interior of human body. PMID:24600172

  13. Standard-Fractionated Radiotherapy for Optic Nerve Sheath Meningioma: Visual Outcome Is Predicted by Mean Eye Dose

    SciTech Connect

    Abouaf, Lucie; Girard, Nicolas; Lefort, Thibaud; D'hombres, Anne; Tilikete, Caroline; Vighetto, Alain; Mornex, Francoise

    2012-03-01

    Purpose: Radiotherapy has shown its efficacy in controlling optic nerve sheath meningiomas (ONSM) tumor growth while allowing visual acuity to improve or stabilize. However, radiation-induced toxicity may ultimately jeopardize the functional benefit. The purpose of this study was to identify predictive factors of poor visual outcome in patients receiving radiotherapy for ONSM. Methods and Materials: We conducted an extensive analysis of 10 patients with ONSM with regard to clinical, radiologic, and dosimetric aspects. All patients were treated with conformal radiotherapy and subsequently underwent biannual neuroophthalmologic and imaging assessments. Pretreatment and posttreatment values of visual acuity and visual field were compared with Wilcoxon's signed rank test. Results: Visual acuity values significantly improved after radiotherapy. After a median follow-up time of 51 months, 6 patients had improved visual acuity, 4 patients had improved visual field, 1 patient was in stable condition, and 1 patient had deteriorated visual acuity and visual field. Tumor control rate was 100% at magnetic resonance imaging assessment. Visual acuity deterioration after radiotherapy was related to radiation-induced retinopathy in 2 patients and radiation-induced mature cataract in 1 patient. Study of radiotherapy parameters showed that the mean eye dose was significantly higher in those 3 patients who had deteriorated vision. Conclusions: Our study confirms that radiotherapy is efficient in treating ONSM. Long-term visual outcome may be compromised by radiation-induced side effects. Mean eye dose has to be considered as a limiting constraint in treatment planning.

  14. Quantitative comparison of dose distribution in radiotherapy plans using 2D gamma maps and X-ray computed tomography

    PubMed Central

    Balosso, Jacques

    2016-01-01

    Background The advanced dose calculation algorithms implemented in treatment planning system (TPS) have remarkably improved the accuracy of dose calculation especially the modeling of electrons transport in the low density medium. The purpose of this study is to evaluate the use of 2D gamma (γ) index to quantify and evaluate the impact of the calculation of electrons transport on dose distribution for lung radiotherapy. Methods X-ray computed tomography images were used to calculate the dose for twelve radiotherapy treatment plans. The doses were originally calculated with Modified Batho (MB) 1D density correction method, and recalculated with anisotropic analytical algorithm (AAA), using the same prescribed dose. Dose parameters derived from dose volume histograms (DVH) and target coverage indices were compared. To compare dose distribution, 2D γ-index was applied, ranging from 1%/1 mm to 6%/6 mm. The results were displayed using γ-maps in 2D. Correlation between DVH metrics and γ passing rates was tested using Spearman’s rank test and Wilcoxon paired test to calculate P values. Results the plans generated with AAA predicted more heterogeneous dose distribution inside the target, with P<0.05. However, MB overestimated the dose predicting more coverage of the target by the prescribed dose. The γ analysis showed that the difference between MB and AAA could reach up to ±10%. The 2D γ-maps illustrated that AAA predicted more dose to organs at risks, as well as lower dose to the target compared to MB. Conclusions Taking into account of the electrons transport on radiotherapy plans showed a significant impact on delivered dose and dose distribution. When considering the AAA represent the true cumulative dose, a readjusting of the prescribed dose and an optimization to protect the organs at risks should be taken in consideration in order to obtain the better clinical outcome. PMID:27429908

  15. In vivo verification of radiation dose delivered to healthy tissue during radiotherapy for breast cancer

    NASA Astrophysics Data System (ADS)

    Lonski, P.; Taylor, M. L.; Hackworth, W.; Phipps, A.; Franich, R. D.; Kron, T.

    2014-03-01

    Different treatment planning system (TPS) algorithms calculate radiation dose in different ways. This work compares measurements made in vivo to the dose calculated at out-of-field locations using three different commercially available algorithms in the Eclipse treatment planning system. LiF: Mg, Cu, P thermoluminescent dosimeter (TLD) chips were placed with 1 cm build-up at six locations on the contralateral side of 5 patients undergoing radiotherapy for breast cancer. TLD readings were compared to calculations of Pencil Beam Convolution (PBC), Anisotropic Analytical Algorithm (AAA) and Acuros XB (XB). AAA predicted zero dose at points beyond 16 cm from the field edge. In the same region PBC returned an unrealistically constant result independent of distance and XB showed good agreement to measured data although consistently underestimated by ~0.1 % of the prescription dose. At points closer to the field edge XB was the superior algorithm, exhibiting agreement with TLD results to within 15 % of measured dose. Both AAA and PBC showed mixed agreement, with overall discrepancies considerably greater than XB. While XB is certainly the preferable algorithm, it should be noted that TPS algorithms in general are not designed to calculate dose at peripheral locations and calculation results in such regions should be treated with caution.

  16. Evaluation of Patient Residual Deviation and Its Impact on Dose Distribution for Proton Radiotherapy

    SciTech Connect

    Arjomandy, Bijan

    2011-10-01

    The residual deviations after final patient repositioning based on bony anatomy and the impact of such deviations on the proton dose distributions was investigated. Digitally reconstructed radiographs (DRRs) and kilovoltage (kV) 'portal verification' images from 10 patients treated with passively scattered proton radiotherapy was used to estimate the residual deviation. These changes were then applied to the location of isocenter points that, in effect, moved the isocenter relative to the apertures and compensators. A composite verification plan was obtained and compared with the original clinical treatment plan to evaluate any changes in dose distributions. The residual deviations were fitted to a Gaussian distribution with {mu} = -0.9 {+-} 0.1 mm and {sigma} = 2.55 {+-} 0.07 mm. The dose distribution showed under- and overcovered dose spots with complex dose distributions both in the target volumes and in the organs at risk. In some cases, this amounts to 63.5% above the intended clinical plan. Although patient positioning is carefully verified before treatment delivery and setup uncertainties are accounted for by using compensator smearing and aperture margins, a residual shift in a patient's position can considerably affect the dose distribution.

  17. Monte Carlo calculation of dose distributions in oligometastatic patients planned for spine stereotactic ablative radiotherapy

    NASA Astrophysics Data System (ADS)

    Moiseenko, V.; Liu, M.; Loewen, S.; Kosztyla, R.; Vollans, E.; Lucido, J.; Fong, M.; Vellani, R.; Popescu, I. A.

    2013-10-01

    Dosimetric consequences of plans optimized using the analytical anisotropic algorithm (AAA) implemented in the Varian Eclipse treatment planning system for spine stereotactic body radiotherapy were evaluated by re-calculating with BEAMnrc/DOSXYZnrc Monte Carlo. Six patients with spinal vertebral metastases were planned using volumetric modulated arc therapy. The planning goal was to cover at least 80% of the planning target volume with a prescribed dose of 35 Gy in five fractions. Tissue heterogeneity-corrected AAA dose distributions for the planning target volume and spinal canal planning organ-at-risk volume were compared against those obtained from Monte Carlo. The results showed that the AAA overestimated planning target volume coverage with the prescribed dose by up to 13.5% (mean 8.3% +/- 3.2%) when compared to Monte Carlo simulations. Maximum dose to spinal canal planning organ-at-risk volume calculated with Monte Carlo was consistently smaller than calculated with the treatment planning system and remained under spinal cord dose tolerance. Differences in dose distribution appear to be related to the dosimetric effects of accounting for body composition in Monte Carlo simulations. In contrast, the treatment planning system assumes that all tissues are water-equivalent in their composition and only differ in their electron density.

  18. Voxel-based population analysis for correlating local dose and rectal toxicity in prostate cancer radiotherapy

    PubMed Central

    Acosta, Oscar; Drean, Gael; Ospina, Juan David; Simon, Antoine; Haigron, Pascal; Lafond, Caroline; De Crevoisier, Renaud

    2013-01-01

    The majority of current models utilized for predicting toxicity in prostate cancer radiotherapy are based on dose-volume histograms. One of their main drawbacks is the lack of spatial accuracy, since they consider the organs as a whole volume and thus ignore the heterogeneous intra-organ radio-sensitivity. In this paper, we propose a dose-image-based framework to reveal the relationships between local dose and toxicity. In this approach, the three-dimensional (3D) planned dose distributions across a population are non-rigidly registered into a common coordinate system and compared at a voxel level, therefore enabling the identification of 3D anatomical patterns, which may be responsible for toxicity, at least to some extent. Additionally, different metrics were employed in order to assess the quality of the dose mapping. The value of this approach was demonstrated by prospectively analyzing rectal bleeding (≥Grade 1 at 2 years) according to the CTCAE v3.0 classification in a series of 105 patients receiving 80Gy to the prostate by IMRT. Within the patients presenting bleeding, a significant dose excess (6Gy on average, p<0.01) was found in a region of the anterior rectal wall. This region, close to the prostate (1cm), represented less than 10% of the rectum. This promising voxel-wise approach allowed subregions to be defined within the organ that may be involved in toxicity and, as such, must be considered during the inverse IMRT planning step. PMID:23528429

  19. Impact of Intrafractional Bowel Gas Movement on Carbon Ion Beam Dose Distribution in Pancreatic Radiotherapy

    SciTech Connect

    Kumagai, Motoki; Hara, Ryusuke; Mori, Shinichiro Yanagi, Takeshi; Asakura, Hiroshi; Kishimoto, Riwa; Kato, Hirotoshi; Yamada, Shigeru; Kandatsu, Susumu; Kamada, Tadashi

    2009-03-15

    Purpose: To assess carbon ion beam dose variation due to bowel gas movement in pancreatic radiotherapy. Methods and Materials: Ten pancreatic cancer inpatients were subject to diagnostic contrast-enhanced dynamic helical CT examination under breath-holding conditions, which included multiple-phase dynamic CT with arterial, venous, and delayed phases. The arterial-venous phase and arterial-delayed phase intervals were 35 and 145 s, respectively. A compensating bolus was designed to cover the target obtained at the arterial phase. Carbon ion dose distribution was calculated by applying the bolus to the CT data sets at the other two phases. Results: Dose conformation to the clinical target volume was degraded by beam overshoot/undershoot due to bowel gas movement. The D95 for clinical target volume was degraded from 98.2% (range, 98.0-99.1%) of the prescribed dose to 94.7% (range, 88.0-99.0%) at 145 s. Excessive dosing to normal tissues varied among tissues and was, for example, 12.2 GyE/13.1 GyE (0 s/145 s) for the cord and 38.8 GyE/39.8 GyE (0 s/145 s) for the duodenum. The magnitude of beam overshoot/undershoot was particularly exacerbated from the anterior and left directions. Conclusions: Bowel gas movement causes dosimetric variation to the target during treatment for radiotherapy. The effect of bowel gas movement varies with beam angle, with greatest influence on the anterior-posterior and left-right beams.

  20. Impact of dose size in single fraction spatially fractionated (grid) radiotherapy for melanoma

    SciTech Connect

    Zhang, Hualin E-mail: hualinzhang@yahoo.com; Zhong, Hualiang; Barth, Rolf F.; Cao, Minsong; Das, Indra J.

    2014-02-15

    Purpose: To evaluate the impact of dose size in single fraction, spatially fractionated (grid) radiotherapy for selectively killing infiltrated melanoma cancer cells of different tumor sizes, using different radiobiological models. Methods: A Monte Carlo technique was employed to calculate the 3D dose distribution of a commercially available megavoltage grid collimator in a 6 MV beam. The linear-quadratic (LQ) and modified linear quadratic (MLQ) models were used separately to evaluate the therapeutic outcome of a series of single fraction regimens that employed grid therapy to treat both acute and late responding melanomas of varying sizes. The dose prescription point was at the center of the tumor volume. Dose sizes ranging from 1 to 30 Gy at 100% dose line were modeled. Tumors were either touching the skin surface or having their centers at a depth of 3 cm. The equivalent uniform dose (EUD) to the melanoma cells and the therapeutic ratio (TR) were defined by comparing grid therapy with the traditional open debulking field. The clinical outcomes from recent reports were used to verify the authors’ model. Results: Dose profiles at different depths and 3D dose distributions in a series of 3D melanomas treated with grid therapy were obtained. The EUDs and TRs for all sizes of 3D tumors involved at different doses were derived through the LQ and MLQ models, and a practical equation was derived. The EUD was only one fifth of the prescribed dose. The TR was dependent on the prescribed dose and on the LQ parameters of both the interspersed cancer and normal tissue cells. The results from the LQ model were consistent with those of the MLQ model. At 20 Gy, the EUD and TR by the LQ model were 2.8% higher and 1% lower than by the MLQ, while at 10 Gy, the EUD and TR as defined by the LQ model were only 1.4% higher and 0.8% lower, respectively. The dose volume histograms of grid therapy for a 10 cm tumor showed different dosimetric characteristics from those of conventional

  1. Reductions in the variations of respiration signals for respiratory-gated radiotherapy when using the video-coaching respiration guiding system

    NASA Astrophysics Data System (ADS)

    Lee, Hyun Jeong; Yea, Ji Woon; Oh, Se An

    2015-07-01

    Respiratory-gated radiation therapy (RGRT) has been used to minimize the dose to normal tissue in lung-cancer radiotherapy. The present research aims to improve the regularity of respiration in RGRT by using a video-coached respiration guiding system. In the study, 16 patients with lung cancer were evaluated. The respiration signals of the patients were measured by using a realtime position management (RPM) respiratory gating system (Varian, USA), and the patients were trained using the video-coaching respiration guiding system. The patients performed free breathing and guided breathing, and the respiratory cycles were acquired for ~5 min. Then, Microsoft Excel 2010 software was used to calculate the mean and the standard deviation for each phase. The standard deviation was computed in order to analyze the improvement in the respiratory regularity with respect to the period and the displacement. The standard deviation of the guided breathing decreased to 48.8% in the inhale peak and 24.2% in the exhale peak compared with the values for the free breathing of patient 6. The standard deviation of the respiratory cycle was found to be decreased when using the respiratory guiding system. The respiratory regularity was significantly improved when using the video-coaching respiration guiding system. Therefore, the system is useful for improving the accuracy and the efficiency of RGRT.

  2. Influence of nuclear interactions in body tissues on tumor dose in carbon-ion radiotherapy

    SciTech Connect

    Inaniwa, T. Kanematsu, N.; Tsuji, H.; Kamada, T.

    2015-12-15

    Purpose: In carbon-ion radiotherapy treatment planning, the planar integrated dose (PID) measured in water is applied to the patient dose calculation with density scaling using the stopping power ratio. Since body tissues are chemically different from water, this dose calculation can be subject to errors, particularly due to differences in inelastic nuclear interactions. In recent studies, the authors proposed and validated a PID correction method for these errors. In the present study, the authors used this correction method to assess the influence of these nuclear interactions in body tissues on tumor dose in various clinical cases. Methods: Using 10–20 cases each of prostate, head and neck (HN), bone and soft tissue (BS), lung, liver, pancreas, and uterine neoplasms, the authors first used treatment plans for carbon-ion radiotherapy without nuclear interaction correction to derive uncorrected dose distributions. The authors then compared these distributions with recalculated distributions using the nuclear interaction correction (corrected dose distributions). Results: Median (25%/75% quartiles) differences between the target mean uncorrected doses and corrected doses were 0.2% (0.1%/0.2%), 0.0% (0.0%/0.0%), −0.3% (−0.4%/−0.2%), −0.1% (−0.2%/−0.1%), −0.1% (−0.2%/0.0%), −0.4% (−0.5%/−0.1%), and −0.3% (−0.4%/0.0%) for the prostate, HN, BS, lung, liver, pancreas, and uterine cases, respectively. The largest difference of −1.6% in target mean and −2.5% at maximum were observed in a uterine case. Conclusions: For most clinical cases, dose calculation errors due to the water nonequivalence of the tissues in nuclear interactions would be marginal compared to intrinsic uncertainties in treatment planning, patient setup, beam delivery, and clinical response. In some extreme cases, however, these errors can be substantial. Accordingly, this correction method should be routinely applied to treatment planning in clinical practice.

  3. Influence of image slice thickness on rectal dose-response relationships following radiotherapy of prostate cancer

    NASA Astrophysics Data System (ADS)

    Olsson, C.; Thor, M.; Liu, M.; Moissenko, V.; Petersen, S. E.; Høyer, M.; Apte, A.; Deasy, J. O.

    2014-07-01

    When pooling retrospective data from different cohorts, slice thicknesses of acquired computed tomography (CT) images used for treatment planning may vary between cohorts. It is, however, not known if varying slice thickness influences derived dose-response relationships. We investigated this for rectal bleeding using dose-volume histograms (DVHs) of the rectum and rectal wall for dose distributions superimposed on images with varying CT slice thicknesses. We used dose and endpoint data from two prostate cancer cohorts treated with three-dimensional conformal radiotherapy to either 74 Gy (N = 159) or 78 Gy (N = 159) at 2 Gy per fraction. The rectum was defined as the whole organ with content, and the morbidity cut-off was Grade ≥2 late rectal bleeding. Rectal walls were defined as 3 mm inner margins added to the rectum. DVHs for simulated slice thicknesses from 3 to 13 mm were compared to DVHs for the originally acquired slice thicknesses at 3 and 5 mm. Volumes, mean, and maximum doses were assessed from the DVHs, and generalized equivalent uniform dose (gEUD) values were calculated. For each organ and each of the simulated slice thicknesses, we performed predictive modeling of late rectal bleeding using the Lyman-Kutcher-Burman (LKB) model. For the most coarse slice thickness, rectal volumes increased (≤18%), whereas maximum and mean doses decreased (≤0.8 and ≤4.2 Gy, respectively). For all a values, the gEUD for the simulated DVHs were ≤1.9 Gy different than the gEUD for the original DVHs. The best-fitting LKB model parameter values with 95% CIs were consistent between all DVHs. In conclusion, we found that the investigated slice thickness variations had minimal impact on rectal dose-response estimations. From the perspective of predictive modeling, our results suggest that variations within 10 mm in slice thickness between cohorts are unlikely to be a limiting factor when pooling multi-institutional rectal dose data that include slice thickness

  4. Influence of Rotations on Dose Distributions in Spinal Stereotactic Body Radiotherapy (SBRT)

    PubMed Central

    Gutfeld, Orit; Kretzler, Annette E; Kashani, Rojano; Tatro, Daniel; Balter, James M

    2009-01-01

    Purpose To evaluate the impact of rotational setup errors on dose distribution in spinal stereotactic body radiotherapy (SBRT). Methods and Materials 39 Cone Beam CT (CBCT) scans from 16 SBRT treatment courses were analyzed. Alignment (including rotation) to the treatment planning CT was performed, followed by translational alignment that reproduced the actual positioning. The planned fluence was then applied to determine the delivered dose to the targets and organs at risk. Results The mean PTV volume was 71.01 mL (SD ± 60.05, range 22.62 – 250.65 mL). Prescribed dose (to the 62 – 82% isodose) was 14 – 30 Gy in one to six fractions. The average rotational displacements were 0.38 ± 1.21, 1.12 ± 1.82 and −0.51 ± 2.0 degrees with maximal rotations of −4.29, 5.76 and −6.64 degrees along the x (pitch), y (yaw), and z (roll) axes, respectively. PTV coverage changed by an average of −0.07 Gy (SD ± 0.20 Gy) between the rotated and the original plan, representing 0.92% of prescription dose (SD ± 2.65%). For the spinal cord, planned with 2 mm expansion to create a planning organ at risk volume (PRV), the difference in minimum dose to the upper 10% of the PRV volume was 0.03 ± 0.3 Gy (maximum 0.9 Gy). Other organs at risk saw insignificant changes in dose. Conclusions PRV expansion generally assures safe treatment delivery in the face of typically encountered rotations. Given the variability of delivered dose within this expansion for certain cases, caution should be taken to properly interpret doses to the cord when considering clinical dose limits. PMID:19306757

  5. Effect of Radiotherapy Volume and Dose on Secondary Cancer Risk in Stage I Testicular Seminoma

    SciTech Connect

    Zwahlen, Daniel R. Martin, Jarad M.; Millar, Jeremy L.; Schneider, Uwe

    2008-03-01

    Purpose: To estimate and compare the secondary cancer risk (SCR) due to para-aortic (PA), dogleg field (DLF), or extensive field (EF) radiotherapy (RT) at different dose levels for Stage I testicular seminoma. Methods and Materials: The organ equivalent dose concept with a linear, plateau, and linear-exponential dose-response model was applied to the dose distributions to estimate the SCR. The dose distributions were calculated in a voxel-based anthropomorphic phantom. Three different three-dimensional plans were computed: PA, DLF, and EF. The plans were calculated with 6-MV photons and two opposed fields, using 20 Gy in 10 fractions. Results: The estimated cumulative SCR for a 75-year-old patient treated with PA-RT at age 35 was 23.3% (linear model), 20.9% (plateau model), and 20.8% (linear-exponential model) compared with 19.8% for the general population. Dependent on the model, PA-RT compared with DLF-RT reduced the SCR by 48-63% or 64-69% when normalized to EF-RT. For PA-RT, the linear dose-response model predicted a decrease of 45% in the SCR, using 20 Gy instead of 30 Gy; the linear-exponential dose-response model predicted no change in SCR. Conclusion: Our model suggested that the SCR after PA-RT for Stage I testicular seminoma is reduced by approximately one-half to two-thirds compared with DLF-RT, independent of the dose-response model. The SCR is expected to be equal or lower with 20 Gy than with 30 Gy. In the absence of mature patient data, the organ equivalent dose concept offers the best potential method of estimating the SCR when discussing treatment options with patients.

  6. Kilovoltage beam Monte Carlo dose calculations in submillimeter voxels for small animal radiotherapy

    PubMed Central

    Bazalova, Magdalena; Zhou, Hu; Keall, Paul J.; Graves, Edward E.

    2009-01-01

    Purpose: Small animal conformal radiotherapy (RT) is essential for preclinical cancer research studies and therefore various microRT systems have been recently designed. The aim of this paper is to efficiently calculate the dose delivered using our microRT system based on a microCT scanner with the Monte Carlo (MC) method and to compare the MC calculations to film measurements. Methods: Doses from 2–30 mm diameter 120 kVp photon beams deposited in a solid water phantom with 0.2×0.2×0.2 mm3 voxels are calculated using the latest versions of the EGSnrc codes BEAMNRC and DOSXYZNRC. Two dose calculation approaches are studied: a two-step approach using phase-space files and direct dose calculation with BEAMNRC simulation sources. Due to the small beam size and submillimeter voxel size resulting in long calculation times, variance reduction techniques are studied. The optimum bremsstrahlung splitting number (NBRSPL in BEAMNRC) and the optimum DOSXYZNRC photon splitting (Nsplit) number are examined for both calculation approaches and various beam sizes. The dose calculation efficiencies and the required number of histories to achieve 1% statistical uncertainty—with no particle recycling—are evaluated for 2–30 mm beams. As a final step, film dose measurements are compared to MC calculated dose distributions. Results: The optimum NBRSPL is approximately 1×106 for both dose calculation approaches. For the dose calculations with phase-space files, Nsplit varies only slightly for 2–30 mm beams and is established to be 300. Nsplit for the DOSXYZNRC calculation with the BEAMNRC source ranges from 300 for the 30 mm beam to 4000 for the 2 mm beam. The calculation time significantly increases for small beam sizes when the BEAMNRC simulation source is used compared to the simulations with phase-space files. For the 2 and 30 mm beams, the dose calculations with phase-space files are more efficient than the dose calculations with BEAMNRC sources by factors of 54 and 1

  7. Image-guided radiotherapy of the prostate using daily CBCT: the feasibility and likely benefit of implementing a margin reduction

    PubMed Central

    Benson, R J; Fairfoul, J; Cook, J; Huddart, R; Poynter, A

    2014-01-01

    Objective: To investigate whether planning target volume (PTV) margins may be safely reduced in radiotherapy of localized prostate cancer incorporating daily online tube potential-cone beam CT (CBCT) image guidance and the anticipated benefit in predicted rectal toxicity. Methods: The prostate-only clinical target volume (CTV2) and rectum were delineated on 1 pre-treatment CBCT each week in 18 randomly selected patients. By transposing these contours onto the original plan, dose–volume histograms (DVHs) for CTV2 and the rectum were each calculated and combined, for each patient, to produce a single mean DVH representative of the dose delivered over the treatment course. Plans were reoptimized using reduced CTV2 to PTV2 margins and the consequent radiobiological impact modelled by the tumour control probability (TCP) and normal tissue complication probability (NTCP) of the rectum. Results: All CBCT images were deemed of sufficient quality to identify the CTV and rectum. No loss of TCP was observed when plans using the standard 5-mm CTV2 to PTV2 margin of the centre were reoptimized with a 4- or 3-mm margin. Margin reduction was associated with a significant decrease in rectal NTCP (5–4 mm; p < 0.05 and 5–3 mm; p < 0.01). Conclusion: Using daily online image guidance with CBCT, a reduction in CTV2 to PTV2 margins to 3 mm is achievable without compromising tumour control. The consequent sparing of surrounding normal tissues is associated with reduced anticipated rectal toxicity. Advances in knowledge: Margin reduction is feasible and potentially beneficial. Centres with image-guided radiotherapy capability should consider assessing whether margin reduction is possible within their institutes. PMID:25354015

  8. SU-E-J-116: Uncertainties Associated with Dose Summation of High-Dose Rate Brachytherapy and Intensity Modulated Radiotherapy for Gynecological Cases

    SciTech Connect

    Kauweloa, K; Bergamo, A; Gutierrez, A; Stathakis, S; Papanikolaou, N; Kirby, N; Mavroidis, P

    2015-06-15

    Purpose: Determining the cumulative dose distribution (CDD) for gynecological patients treated with both high-dose rate (HDR) brachytherapy and intensity-modulated radiotherapy (IMRT) is challenging. The purpose of this work is to study the uncertainty of performing this with a structure-guided deformable (SGD) approach in Velocity. Methods: For SGD, the Hounsfield units inside specified contours are overridden to set uniform values. Deformable image registration (DIR) is the run on these process images, which forces the DIR to focus on these contour boundaries. 18 gynecological cancer patients were used in this study. The original bladder and rectum planning contours for these patients were used to drive the SGD. A second set of contours were made of the bladder by the same person with the intent of carefully making them completely consistent with each other. This second set was utilized to evaluate the spatial accuracy of the SGD. The determined spatial accuracy was then multiplied by the local dose gradient to determine a dose uncertainty associated with the SGD dose warping. The normal tissue complication probability (NTCP) was then calculated for each dose volume histogram (DVH) that included four different probabilistic uncertainties associated with the spatial errors (e.g., 68.3% and 95.4%). Results: The NTCPs for each DVH (e.g., NTCP-−95.4%, NTCP-−68.3%, NTCP-68.3%, NTCP-95.4%) differed amongst patients. All patients had an NTCP-−95.4% close to 0%, while NTCP-95.4% ranged from 0.67% to 100%. Nine patients had an NTCP-−95.4% less than 50% while the remaining nine patients had NTCP-95.4% greater than 50%. Conclusion: The uncertainty associated with this CDD technique renders a large NTCP uncertainty. Thus, it is currently not practical for clinical use. The two ways to improve this would be to use more precise contours to drive the SGD and to use a more accurate DIR algorithm.

  9. Sensitivity analysis for dose deposition in radiotherapy via a Fokker–Planck model

    DOE PAGESBeta

    Barnard, Richard C.; Frank, Martin; Krycki, Kai

    2016-02-09

    In this paper, we study the sensitivities of electron dose calculations with respect to stopping power and transport coefficients. We focus on the application to radiotherapy simulations. We use a Fokker–Planck approximation to the Boltzmann transport equation. Equations for the sensitivities are derived by the adjoint method. The Fokker–Planck equation and its adjoint are solved numerically in slab geometry using the spherical harmonics expansion (PN) and an Harten-Lax-van Leer finite volume method. Our method is verified by comparison to finite difference approximations of the sensitivities. Finally, we present numerical results of the sensitivities for the normalized average dose deposition depthmore » with respect to the stopping power and the transport coefficients, demonstrating the increase in relative sensitivities as beam energy decreases. In conclusion, this in turn gives estimates on the uncertainty in the normalized average deposition depth, which we present.« less

  10. A matheuristic for the selection of beam directions and dose distribution in Radiotherapy Planning

    NASA Astrophysics Data System (ADS)

    Obal, T. M.; Florentino, H. O.; Gevert, V. G.; Jones, D. F.; Ouelhadj, D.; Volpi, N. M. P.; Wilhelm, V. E.

    2015-05-01

    In this paper a matheuristic using a combined Genetic Algorithm (GA) and exact method approach is proposed for selecting the position of the beams and dose distribution in Intensity Modulated Radiotherapy Planning (IMRT). GA selects a set of beams, for which the dose distribution is determined in the process of the GA's evaluation, using an optimisation model that is solved by an Interior Point method. Two instances are used to evaluate the performance of the matheuristic, comparing to the optimum solution, in terms of solution and computation time, found using the exact methodology of Branch and Bound. The results show that the matheuristic is appropriate to this problem in the case study proposed, as it is extremely faster than the exact method and also have reached the optimum solution in several experiments done.

  11. Equivalence of Gyn GEC-ESTRO guidelines for image guided cervical brachytherapy with EUD-based dose prescription

    PubMed Central

    2013-01-01

    Background To establish a generalized equivalent uniform dose (gEUD) -based prescription method for Image Guided Brachytherapy (IGBT) that reproduces the Gyn GEC-ESTRO WG (GGE) prescription for cervix carcinoma patients on CT images with limited soft tissue resolution. Methods The equivalence of two IGBT planning approaches was investigated in 20 patients who received external beam radiotherapy (EBT) and 5 concomitant high dose rate IGBT treatments. The GGE planning strategy based on dose to the most exposed 2 cm3 (D2cc) was used to derive criteria for the gEUD-based planning of the bladder and rectum. The safety of gEUD constraints in terms of GGE criteria was tested by maximizing dose to the gEUD constraints for individual fractions. Results The gEUD constraints of 3.55 Gy for the rectum and 5.19 Gy for the bladder were derived. Rectum and bladder gEUD-maximized plans resulted in D2cc averages very similar to the initial GGE criteria. Average D2ccs and EUDs from the full treatment course were comparable for the two techniques within both sets of normal tissue constraints. The same was found for the tumor doses. Conclusions The derived gEUD criteria for normal organs result in GGE-equivalent IGBT treatment plans. The gEUD-based planning considers the entire dose distribution of organs in contrast to a single dose-volume-histogram point. PMID:24225184

  12. A comparison of Monte Carlo and model-based dose calculations in radiotherapy using MCNPTV

    NASA Astrophysics Data System (ADS)

    Wyatt, Mark S.; Miller, Laurence F.

    2006-06-01

    Monte Carlo calculations for megavoltage radiotherapy beams represent the next generation of dose calculation in the clinical environment. In this paper, calculations obtained by the MCNP code based on CT data from a human pelvis are compared against those obtained by a commercial radiotherapy treatment system (CMS XiO). The MCNP calculations are automated by the use of MCNPTV (MCNP Treatment Verification), an integrated application developed in Visual Basic that runs on a Windows-based PC. The linear accelerator beam is modeled as a finite point source, and validated by comparing depth dose curves and lateral profiles in a water phantom to measured data. Calculated water phantom PDDs are within 1% of measured data, but the lateral profiles exhibit differences of 2.4, 5.5, and 5.7 mm at the 60%, 40%, and 20% isodose lines, respectively. A MCNP calculation is performed using the CT data and 15 points are selected for comparison with XiO. Results are generally within the uncertainty of the MCNP calculation, although differences up to 13.2% are seen in the presence of large heterogeneities.

  13. The Radiobiological Basis for Improvements in Radiotherapy and Low Dose Risk Assessment

    SciTech Connect

    Hei, Tom K

    2009-12-09

    Overall Goal: This conference grant was proposed to organize and host an international conference at Columbia University in New York to critically assess the cellular and molecular signaling events and tissue response following radiation damage. The conference would also serve as a venue to play tribute to the more than forty years contributions made by Professor Eric J. Hall to the radiation biology field. The goals of the meeting were to examine tumor hypoxia and sensitizer development; recent advances made in clinical radiotherapy; addressed several low dose phenomena, including genomic instability and bystander effects that are important in radiation risk assessment. Study and Results: The symposium was held on October 13th and 14th, 2008 at the Alfred Lerner Hall in the Morningside campus of Columbia University. The symposium, entitled “From Beans to Genes: A Forty Year Odyssey in Radiation Biology” was attended by more than 120 faculty, scientists, clinicians, fellows and students. The symposium, spanned over a day and a half, covered four scientific themes. These included tumor hypoxia and radiosensitizers; low dose radiation response; radiation biology in the practice of radiotherapy, and radiation hazard in space and genetic predisposition to cancer. The program of the symposium is as follow:

  14. Effective Doses in Four-Dimensional Computed Tomography for Lung Radiotherapy Planning

    SciTech Connect

    Mori, Shinichiro Ko, Susumu; Ishii, Takayoshi; Nishizawa, Kanae

    2009-04-01

    The recent broad adoption of 4-D computed tomography (4DCT) scanning in radiotherapy has allowed the accurate determination of the target volume of tumors by minimizing image degradation caused by respiratory motion. Although the radiation exposure of the treatment beam is significantly greater than that of CT scans used for treatment planning, it is important to recognize and optimize the radiation exposure in 4DCT from the radiological protection point of view. Here, radiation exposure in 4DCT was measured with a 16 multidetector CT. Organ doses were measured using thermoluminescence radiation dosimeter chips inserted at respective anatomical sites of an anthropomorphic phantom. Results were compared with those with the helical CT scan mode. The effective dose measured for 4DCT was 24.7 mSv, approximately four times higher than that for helical CT. However, the increase in treatment accuracy afforded by 4DCT means its use in radiotherapy is inevitable. The patient exposure in the 4DCT could be of value by clarifying the advantage of the treatment planning using 4DCT.

  15. High-dose radiotherapy in inoperable nonsmall cell lung cancer: comparison of volumetric modulated arc therapy, dynamic IMRT and 3D conformal radiotherapy.

    PubMed

    Bree, Ingrid de; van Hinsberg, Mariëlle G E; van Veelen, Lieneke R

    2012-01-01

    Conformal 3D radiotherapy (3D-CRT) combined with chemotherapy for inoperable non-small cell lung cancer (NSCLC) to the preferable high dose is often not achievable because of dose-limiting organs. This reduces the probability of regional tumor control. Therefore, the surplus value of using intensity-modulated radiation therapy (IMRT) techniques, specifically volumetric modulated arc therapy (RapidArc [RA]) and dynamic IMRT (d-IMRT) has been investigated. RA and d-IMRT plans were compared with 3D-CRT treatment plans for 20 patients eligible for concurrent high-dose chemoradiotherapy, in whom a dose of 60 Gy was not achievable. Comparison of dose delivery in the target volume and organs at risk was carried out by evaluating 3D dose distributions and dose-volume histograms. Quality of the dose distribution was assessed using the inhomogeneity and conformity index. For most patients, a higher dose to the target volume can be delivered using RA or d-IMRT; in 15% of the patients a dose ≥60 Gy was possible. Both IMRT techniques result in a better conformity of the dose (p < 0.001). There are no significant differences in homogeneity of dose in the target volume. IMRT techniques for NSCLC patients allow higher dose to the target volume, thus improving regional tumor control. PMID:22459649

  16. The influence of patient positioning uncertainties in proton radiotherapy on proton range and dose distributions

    SciTech Connect

    Liebl, Jakob; Paganetti, Harald; Zhu, Mingyao; Winey, Brian A.

    2014-09-15

    Purpose: Proton radiotherapy allows radiation treatment delivery with high dose gradients. The nature of such dose distributions increases the influence of patient positioning uncertainties on their fidelity when compared to photon radiotherapy. The present work quantitatively analyzes the influence of setup uncertainties on proton range and dose distributions. Methods: Thirty-eight clinical passive scattering treatment fields for small lesions in the head were studied. Dose distributions for shifted and rotated patient positions were Monte Carlo-simulated. Proton range uncertainties at the 50%- and 90%-dose falloff position were calculated considering 18 arbitrary combinations of maximal patient position shifts and rotations for two patient positioning methods. Normal tissue complication probabilities (NTCPs), equivalent uniform doses (EUDs), and tumor control probabilities (TCPs) were studied for organs at risk (OARs) and target volumes of eight patients. Results: The authors identified a median 1σ proton range uncertainty at the 50%-dose falloff of 2.8 mm for anatomy-based patient positioning and 1.6 mm for fiducial-based patient positioning as well as 7.2 and 5.8 mm for the 90%-dose falloff position, respectively. These range uncertainties were correlated to heterogeneity indices (HIs) calculated for each treatment field (38% < R{sup 2} < 50%). A NTCP increase of more than 10% (absolute) was observed for less than 2.9% (anatomy-based positioning) and 1.2% (fiducial-based positioning) of the studied OARs and patient shifts. For target volumes TCP decreases by more than 10% (absolute) occurred in less than 2.2% of the considered treatment scenarios for anatomy-based patient positioning and were nonexistent for fiducial-based patient positioning. EUD changes for target volumes were up to 35% (anatomy-based positioning) and 16% (fiducial-based positioning). Conclusions: The influence of patient positioning uncertainties on proton range in therapy of small lesions

  17. A dosimetry technique for measuring kilovoltage cone-beam CT dose on a linear accelerator using radiotherapy equipment.

    PubMed

    Scandurra, Daniel; Lawford, Catherine E

    2014-01-01

    This work develops a technique for kilovoltage cone-beam CT (CBCT) dosimetry that incorporates both point dose and integral dose in the form of dose length product, and uses readily available radiotherapy equipment. The dose from imaging protocols for a range of imaging parameters and treatment sites was evaluated. Conventional CT dosimetry using 100 mm long pencil chambers has been shown to be inadequate for the large fields in CBCT and has been replaced in this work by a combination of point dose and integral dose. Absolute dose measurements were made with a small volume ion chamber at the central slice of a radiotherapy phantom. Beam profiles were measured using a linear diode array large enough to capture the entire imaging field. These profiles were normalized to absolute dose to form dose line integrals, which were then weighted with radial depth to form the DLPCBCT. This metric is analogous to the standard dose length product (DLP), but derived differently to suit the unique properties of CBCT. Imaging protocols for head and neck, chest, and prostate sites delivered absolute doses of 0.9, 2.2, and 2.9 cGy to the center of the phantom, and DLPCBCT of 28.2, 665.1, and 565.3mGy.cm, respectively. Results are displayed as dose per 100 mAs and as a function of key imaging parameters such as kVp, mAs, and collimator selection in a summary table. DLPCBCT was found to correlate closely with the dimension of the imaging region and provided a good indication of integral dose. It is important to assess integral dose when determining radiation doses to patients using CBCT. By incorporating measured beam profiles and DLP, this technique provides a CBCT dosimetry in radiotherapy phantoms and allows the prediction of imaging dose for new CBCT protocols. PMID:25207398

  18. Predictors of Mastoiditis after Intensity-Modulated Radiotherapy in Nasopharyngeal Carcinoma: A Dose-Volume Analysis

    PubMed Central

    Yao, Ji-Jin; Zhou, Guan-Qun; Jin, Ya-Nan; Zhang, Wang-Jian; Lin, Li; Yu, Xiao-Li; Shao, Jian-Yong; Ma, Jun; Sun, Ying

    2016-01-01

    Background: To identify predictors for development of mastoiditis after intensity-modulated radiation therapy (IMRT) in nasopharyngeal carcinoma (NPC). Methods: Data for 146 NPC patients treated with IMRT was retrospectively reviewed under institutional ethics committee approval. Clinical factors associated with mastoiditis were analyzed. Dose-volume histogram analysis was performed for the Eustachian tube, tympanic cavity, mastoid air cells, cochlea, internal auditory canal and vestibular apparatus to relate doses to radiographic changes in the mastoid. Mastoiditis was assessed using magnetic resonance imaging and was classified as Grade 0 (none), 1 (mild), 2 (moderate) or 3 (severe); Grade 3 mastoiditis was the study end-point. Results: Eighty-eight ears (36%) had radiation-induced mastoiditis: 38/244 (15.6%) mastoid complexes had Grade 1-2 mastoiditis and 50/244 (20.5%) mastoid complexes had Grade 3 mastoiditis. Multivariate analysis revealed a mastoid mean dose > 35.93 Gy (odds ratio [OR]=4.22, P=.003), Eustachian tube mean dose > 53.43 Gy (OR=2.16, P=.034) and advanced T category (T3 and T4; OR=10.33, P=.032) were negative prognostic factors for Grade 3 mastoiditis. Conclusions: Radiation-induced mastoiditis remains a common late toxicity in NPC after radiotherapy. The mean dose to the mastoid air cells and Eustachian tube should be limited to reduce the risk of radiation-induced mastoiditis. PMID:26918040

  19. A self-adaptive case-based reasoning system for dose planning in prostate cancer radiotherapy

    SciTech Connect

    Mishra, Nishikant; Petrovic, Sanja; Sundar, Santhanam

    2011-12-15

    Purpose: Prostate cancer is the most common cancer in the male population. Radiotherapy is often used in the treatment for prostate cancer. In radiotherapy treatment, the oncologist makes a trade-off between the risk and benefit of the radiation, i.e., the task is to deliver a high dose to the prostate cancer cells and minimize side effects of the treatment. The aim of our research is to develop a software system that will assist the oncologist in planning new treatments. Methods: A nonlinear case-based reasoning system is developed to capture the expertise and experience of oncologists in treating previous patients. Importance (weights) of different clinical parameters in the dose planning is determined by the oncologist based on their past experience, and is highly subjective. The weights are usually fixed in the system. In this research, the weights are updated automatically each time after generating a treatment plan for a new patient using a group based simulated annealing approach. Results: The developed approach is analyzed on the real data set collected from the Nottingham University Hospitals NHS Trust, City Hospital Campus, UK. Extensive experiments show that the dose plan suggested by the proposed method is coherent with the dose plan prescribed by an experienced oncologist or even better. Conclusions: The developed case-based reasoning system enables the use of knowledge and experience gained by the oncologist in treating new patients. This system may play a vital role to assist the oncologist in making a better decision in less computational time; it utilizes the success rate of the previously treated patients and it can also be used in teaching and training processes.

  20. Delay differential equations and the dose-time dependence of early radiotherapy reactions

    SciTech Connect

    Fenwick, John D.

    2006-09-15

    The dose-time dependence of early radiotherapy reactions impacts on the design of accelerated fractionation schedules--oral mucositis, for example, can be dose limiting for short treatments designed to avoid tumor repopulation. In this paper a framework for modeling early reaction dose-time dependence is developed. Variation of stem cell number with time after the start of a radiation schedule is modeled using a first-order delay differential equation (DDE), motivated by experimental observations linking the speed of compensatory proliferation in early reacting tissues to the degree of tissue damage. The modeling suggests that two types of early reaction radiation response are possible, stem cell numbers either monotonically approaching equilibrium plateau levels or overshooting before returning to equilibrium. Several formulas have been derived from the delay differential equation, predicting changes in isoeffective total radiation dose with schedule duration for different types of fractionation scheme. The formulas have been fitted to a wide range of published animal early reaction data, the fits all implying a degree of overshoot. Results are presented illustrating the scope of the delay differential model: most of the data are fitted well, although the model struggles with a few datasets measured for schedules with distinctive dose-time patterns. Ways of extending the current model to cope with these particular dose-time patterns are briefly discussed. The DDE approach is conceptually more complex than earlier descriptive dose-time models but potentially more powerful. It can be used to study issues not addressed by simpler models, such as the likely effects of increasing or decreasing the dose-per-day over time, or of splitting radiation courses into intense segments separated by gaps. It may also prove useful for modeling the effects of chemoirradiation.

  1. Dosimetric verification of stereotactic radiosurgery/stereotactic radiotherapy dose distributions using Gafchromic EBT3

    SciTech Connect

    Cusumano, Davide; Fumagalli, Maria L.; Marchetti, Marcello; Fariselli, Laura; De Martin, Elena

    2015-10-01

    Aim of this study is to examine the feasibility of using the new Gafchromic EBT3 film in a high-dose stereotactic radiosurgery and radiotherapy quality assurance procedure. Owing to the reduced dimensions of the involved lesions, the feasibility of scanning plan verification films on the scanner plate area with the best uniformity rather than using a correction mask was evaluated. For this purpose, signal values dispersion and reproducibility of film scans were investigated. Uniformity was then quantified in the selected area and was found to be within 1.5% for doses up to 8 Gy. A high-dose threshold level for analyses using this procedure was established evaluating the sensitivity of the irradiated films. Sensitivity was found to be of the order of centiGray for doses up to 6.2 Gy and decreasing for higher doses. The obtained results were used to implement a procedure comparing dose distributions delivered with a CyberKnife system to planned ones. The procedure was validated through single beam irradiation on a Gafchromic film. The agreement between dose distributions was then evaluated for 13 patients (brain lesions, 5 Gy/die prescription isodose ~80%) using gamma analysis. Results obtained using Gamma test criteria of 5%/1 mm show a pass rate of 94.3%. Gamma frequency parameters calculation for EBT3 films showed to strongly depend on subtraction of unexposed film pixel values from irradiated ones. In the framework of the described dosimetric procedure, EBT3 films proved to be effective in the verification of high doses delivered to lesions with complex shapes and adjacent to organs at risk.

  2. [Evaluation of absorbed dose from kilovoltage cone-beam computed tomography by radiotherapy planning system: influence on the radiation therapy for prostate cancer].

    PubMed

    Kawamura, Tetsuro; Murakami, Naoki; Okamura, Yoshiaki; Nishimura, Hideki; Miyawaki, Daisuke; Kimura, Kunihiko; Hase, Mamoru; Sasaki, Ryohei

    2013-05-01

    Image-guided radiation therapy (IGRT) is increasingly being used in modern radiation therapy, and it is now possible to verify a patient's position using kilo-voltage cone-beam computed tomography (kV-CBCT). However, if kV-CBCT is used frequently, the dose absorbed by the body cannot be disregarded. A number of studies have been made on the absorbed dose of kV-CBCT, in which absorbed dose measurements were made using a computed tomography dose index (CTDI) or a thermoluminescent dosimeter (TLD). Other methods include comparison of the absorbed dose between a kV-CBCT and other modalities. These techniques are now in common use. However, dose distribution within the patient varies with the patient's size, posture and the part of the body to which radiation therapy is applied. The chief purpose of this study was to evaluate the dose distribution of kV-CBCT by employing a radiotherapy planning system (RTPS); a secondary aim was to examine the influence of a dose of kV-CBCT radiation when used to treat prostate cancer. The beam data of an on-board imager (OBI) was registered in the RTPS, after which modeling was performed. The radiation dosimetry was arranged by the dosimeter in an elliptical phantom. Rotational radiation treatment was used to obtain the dose distribution of the kV-CBCT within the patient, and the patient dose was evaluated based on the simulation of the dose distribution. In radiation therapy for prostate cancer, if kV-CBCT was applied daily, the dose increment within the planning target volume (PTV) and the organ in question was about 1 Gy. PMID:23964528

  3. Superiority of helical tomotherapy on liver sparing and dose escalation in hepatocellular carcinoma: a comparison study of three-dimensional conformal radiotherapy and intensity-modulated radiotherapy

    PubMed Central

    Zhao, Qianqian; Wang, Renben; Zhu, Jian; Jin, Linzhi; Zhu, Kunli; Xu, Xiaoqing; Feng, Rui; Jiang, Shumei; Qi, Zhonghua; Yin, Yong

    2016-01-01

    Background and purpose To compare the difference of liver sparing and dose escalation between three-dimensional conformal radiotherapy (3DCRT), intensity-modulated radiotherapy (IMRT), and helical tomotherapy (HT) for hepatocellular carcinoma. Patients and methods Sixteen unresectable HCC patients were enrolled in this study. First, some evaluation factors of 3DCRT, IMRT, and HT plans were calculated with prescription dose at 50 Gy/25 fractions. Then, the doses were increased using HT or IMRT independently until either the plans reached 70 Gy or any normal tissue reached the dose limit according to quantitative analysis of normal tissue effects in the clinic criteria. Results The conformal index of 3DCRT was lower than that of IMRT (P<0.001) or HT (P<0.001), and the homogeneity index of 3DCRT was higher than that of IMRT (P<0.001) or HT (P<0.001). HT took the longest treatment time (P<0.001). For V50% (fraction of normal liver treated to at least 50% of the isocenter dose) of the normal liver, there was a significant difference: 3DCRT > IMRT > HT (P<0.001). HT had a lower Dmean (mean dose) and V20 (Vn, the percentage of organ volume receiving ≥n Gy) of liver compared with 3DCRT (P=0.005 and P=0.005, respectively) or IMRT (P=0.508 and P=0.007, respectively). Dmean of nontarget normal liver and V30 of liver were higher for 3DCRT than IMRT (P=0.005 and P=0.005, respectively) or HT (P=0.005 and P=0.005, respectively). Seven patients in IMRT (43.75%) and nine patients in HT (56.25%) reached the isodose 70 Gy, meeting the dose limit of the organs at risk. Conclusion HT may provide significantly better liver sparing and allow more patients to achieve higher prescription dose in HCC radiotherapy. PMID:27445485

  4. TU-F-17A-08: The Relative Accuracy of 4D Dose Accumulation for Lung Radiotherapy Using Rigid Dose Projection Versus Dose Recalculation On Every Breathing Phase

    SciTech Connect

    Lamb, J; Lee, C; Tee, S; Lee, P; Iwamoto, K; Low, D; Valdes, G; Robinson, C

    2014-06-15

    Purpose: To investigate the accuracy of 4D dose accumulation using projection of dose calculated on the end-exhalation, mid-ventilation, or average intensity breathing phase CT scan, versus dose accumulation performed using full Monte Carlo dose recalculation on every breathing phase. Methods: Radiotherapy plans were analyzed for 10 patients with stage I-II lung cancer planned using 4D-CT. SBRT plans were optimized using the dose calculated by a commercially-available Monte Carlo algorithm on the end-exhalation 4D-CT phase. 4D dose accumulations using deformable registration were performed with a commercially available tool that projected the planned dose onto every breathing phase without recalculation, as well as with a Monte Carlo recalculation of the dose on all breathing phases. The 3D planned dose (3D-EX), the 3D dose calculated on the average intensity image (3D-AVE), and the 4D accumulations of the dose calculated on the end-exhalation phase CT (4D-PR-EX), the mid-ventilation phase CT (4D-PR-MID), and the average intensity image (4D-PR-AVE), respectively, were compared against the accumulation of the Monte Carlo dose recalculated on every phase. Plan evaluation metrics relating to target volumes and critical structures relevant for lung SBRT were analyzed. Results: Plan evaluation metrics tabulated using 4D-PR-EX, 4D-PR-MID, and 4D-PR-AVE differed from those tabulated using Monte Carlo recalculation on every phase by an average of 0.14±0.70 Gy, - 0.11±0.51 Gy, and 0.00±0.62 Gy, respectively. Deviations of between 8 and 13 Gy were observed between the 4D-MC calculations and both 3D methods for the proximal bronchial trees of 3 patients. Conclusions: 4D dose accumulation using projection without re-calculation may be sufficiently accurate compared to 4D dose accumulated from Monte Carlo recalculation on every phase, depending on institutional protocols. Use of 4D dose accumulation should be considered when evaluating normal tissue complication

  5. Patient doses from fluoroscopically guided cardiac procedures in pediatrics

    NASA Astrophysics Data System (ADS)

    Martinez, L. C.; Vano, E.; Gutierrez, F.; Rodriguez, C.; Gilarranz, R.; Manzanas, M. J.

    2007-08-01

    Infants and children are a higher risk population for radiation cancer induction compared to adults. Although some values on pediatric patient doses for cardiac procedures have been reported, data to determine reference levels are scarce, especially when compared to those available for adults in diagnostic and therapeutic procedures. The aim of this study is to make a new contribution to the scarce published data in pediatric cardiac procedures and help in the determination of future dose reference levels. This paper presents a set of patient dose values, in terms of air kerma area product (KAP) and entrance surface air kerma (ESAK), measured in a pediatric cardiac catheterization laboratory equipped with a biplane x-ray system with dynamic flat panel detectors. Cardiologists were properly trained in radiation protection. The study includes 137 patients aged between 10 days and 16 years who underwent diagnostic catheterizations or therapeutic procedures. Demographic data and technical details of the procedures were also gathered. The x-ray system was submitted to a quality control programme, including the calibration of the transmission ionization chamber. The age distribution of the patients was 47 for <1 year; 52 for 1-<5 years; 25 for 5-<10 years and 13 for 10-<16 years. Median values of KAP were 1.9, 2.9, 4.5 and 15.4 Gy cm2 respectively for the four age bands. These KAP values increase by a factor of 8 when moving through the four age bands. The probability of a fatal cancer per fluoroscopically guided cardiac procedure is about 0.07%. Median values of ESAK for the four age bands were 46, 50, 56 and 163 mGy, which lie far below the threshold for deterministic effects on the skin. These dose values are lower than those published in previous papers.

  6. An analytic model of neutron ambient dose equivalent and equivalent dose for proton radiotherapy

    PubMed Central

    Zhang, Rui; Pérez-Andújar, Angélica; Fontenot, Jonas D; Taddei, Phillip J; Newhauser, Wayne D

    2010-01-01

    Stray neutrons generated in passively scattered proton therapy are of concern because they increase the risk that a patient will develop a second cancer. Several investigations characterized stray neutrons in proton therapy using experimental measurements and Monte Carlo simulations, but capabilities of analytical methods to predict neutron exposures are less well developed. The goal of this study was to develop a new analytical model to calculate neutron ambient dose equivalent in air and equivalent dose in phantom based on Monte Carlo modeling of a passively scattered proton therapy unit. The accuracy of the new analytical model is superior to a previous analytical model and comparable to the accuracy of typical Monte Carlo simulations and measurements. Predictions from the new analytical model agreed reasonably well with corresponding values predicted by a Monte Carlo code using an anthropomorphic phantom. PMID:21076197

  7. Dose to Larynx Predicts for Swallowing Complications After Intensity-Modulated Radiotherapy

    SciTech Connect

    Caglar, Hale B.; Tishler, Roy B.; Burke, Elaine; Li Yi; Goguen, Laura; Norris, Carl M.; Allen, Aaron M.

    2008-11-15

    Purpose: To evaluate early swallowing after intensity-modulated radiotherapy for head and neck squamous cell carcinoma and determine factors correlating with aspiration and/or stricture. Methods and Materials: Consecutive patients treated with intensity-modulated radiotherapy with or without chemotherapy between September 2004 and August 2006 at the Dana Farber Cancer Institute/Brigham and Women's Hospital were evaluated with institutional review board approval. Patients underwent swallowing evaluation after completion of therapy; including video swallow studies. The clinical- and treatment-related variables were examined for correlation with aspiration or strictures, as well as doses to the larynx, pharyngeal constrictor muscles, and cervical esophagus. The correlation was assessed with logistic regression analysis. Results: A total of 96 patients were evaluated. Their median age was 55 years, and 79 (82%) were men. The primary site of cancer was the oropharynx in 43, hypopharynx/larynx in 17, oral cavity in 13, nasopharynx in 11, maxillary sinus in 2, and unknown primary in 10. Of the 96 patients, 85% underwent definitive RT and 15% postoperative RT. Also, 28 patients underwent induction chemotherapy followed by concurrent chemotherapy, 59 received concurrent chemotherapy, and 9 patients underwent RT alone. The median follow-up was 10 months. Of the 96 patients, 31 (32%) had clinically significant aspiration and 36 (37%) developed a stricture. The radiation dose-volume metrics, including the volume of the larynx receiving {>=}50 Gy (p = 0.04 and p = 0.03, respectively) and volume of the inferior constrictor receiving {>=}50 Gy (p = 0.05 and p = 0.02, respectively) were significantly associated with both aspiration and stricture. The mean larynx dose correlated with aspiration (p = 0.003). Smoking history was the only clinical factor to correlate with stricture (p = 0.05) but not aspiration. Conclusion: Aspiration and stricture are common side effects after

  8. Re-irradiation of unresectable recurrent head and neck cancer: using Helical Tomotherapy as image-guided intensity-modulated radiotherapy

    PubMed Central

    Jeong, Songmi; Yoo, Eun Jung; Kim, Ji Yoon; Han, Chi Wha; Kim, Ki Jun

    2013-01-01

    Purpose Re-irradiation (re-RT) is considered a treatment option for inoperable locoregionally recurrent head and neck cancer (HNC) after prior radiotherapy. We evaluated the efficacy and safety of re-RT using Helical Tomotherapy as image-guided intensity-modulated radiotherapy in recurrent HNC. Materials and Methods Patients diagnosed with recurrent HNC and received re-RT were retrospectively reviewed. Primary endpoint was overall survival (OS) and secondary endpoints were locoregional control and toxicities. Results The median follow-up period of total 9 patients was 18.7 months (range, 4.1 to 76 months) and that of 3 alive patients was 49 months (range, 47 to 76 months). Median dose of first radiotherapy and re-RT was 64.8 and 47.5 Gy10. Median cumulative dose of the two courses of radiotherapy was 116.3 Gy10 (range, 91.8 to 128.9 Gy10) while the median interval between the two courses of radiation was 25 months (range, 4 to 137 months). The response rate after re-RT of the evaluated 8 patients was 75% (complete response, 4; partial response, 2). Median locoregional relapse-free survival after re-RT was 11.9 months (range, 3.4 to 75.1 months) and 5 patients eventually presented with treatment failure (in-field failure, 2; in- and out-field failure, 2; out-field failure, 1). Median OS of the 8 patients was 20.3 months (range, 4.1 to 75.1 months). One- and two-year OS rates were 62.5% and 50%, respectively. Grade 3 leucopenia developed in one patient as acute toxicity, and grade 2 osteonecrosis and trismus as chronic toxicity in another patient. Conclusion Re-RT using Helical Tomotherapy for previously irradiated patients with unresectable locoregionally recurrent HNC may be a feasible treatment option with long-term survival and acceptable toxicities. PMID:24501708

  9. Patient radiation dose audits for fluoroscopically guided interventional procedures

    SciTech Connect

    Balter, Stephen; Rosenstein, Marvin; Miller, Donald L.; Schueler, Beth; Spelic, David

    2011-03-15

    Purpose: Quality management for any use of medical x-ray imaging should include monitoring of radiation dose. Fluoroscopically guided interventional (FGI) procedures are inherently clinically variable and have the potential for inducing deterministic injuries in patients. The use of a conventional diagnostic reference level is not appropriate for FGI procedures. A similar but more detailed quality process for management of radiation dose in FGI procedures is described. Methods: A method that takes into account both the inherent variability of FGI procedures and the risk of deterministic injuries from these procedures is suggested. The substantial radiation dose level (SRDL) is an absolute action level (with regard to patient follow-up) below which skin injury is highly unlikely and above which skin injury is possible. The quality process for FGI procedures collects data from all instances of a given procedure from a number of facilities into an advisory data set (ADS). An individual facility collects a facility data set (FDS) comprised of all instances of the same procedure at that facility. The individual FDS is then compared to the multifacility ADS with regard to the overall shape of the dose distributions and the percent of instances in both the ADS and the FDS that exceed the SRDL. Results: Samples of an ADS and FDS for percutaneous coronary intervention, using the dose metric of reference air kerma (K{sub a,r}) (i.e., the cumulative air kerma at the reference point), are used to illustrate the proposed quality process for FGI procedures. Investigation is warranted whenever the FDS is noticeably different from the ADS for the specific FGI procedure and particularly in two circumstances: (1) When the facility's local median K{sub a,r} exceeds the 75th percentile of the ADS and (2) when the percent of instances where K{sub a,r} exceeds the facility-selected SRDL is greater for the FDS than for the ADS. Conclusions: Analysis of the two data sets (ADS and FDS) and

  10. Development of a deformable dosimetric phantom to verify dose accumulation algorithms for adaptive radiotherapy.

    PubMed

    Zhong, Hualiang; Adams, Jeffrey; Glide-Hurst, Carri; Zhang, Hualin; Li, Haisen; Chetty, Indrin J

    2016-01-01

    Adaptive radiotherapy may improve treatment outcomes for lung cancer patients. Because of the lack of an effective tool for quality assurance, this therapeutic modality is not yet accepted in clinic. The purpose of this study is to develop a deformable physical phantom for validation of dose accumulation algorithms in regions with heterogeneous mass. A three-dimensional (3D) deformable phantom was developed containing a tissue-equivalent tumor and heterogeneous sponge inserts. Thermoluminescent dosimeters (TLDs) were placed at multiple locations in the phantom each time before dose measurement. Doses were measured with the phantom in both the static and deformed cases. The deformation of the phantom was actuated by a motor driven piston. 4D computed tomography images were acquired to calculate 3D doses at each phase using Pinnacle and EGSnrc/DOSXYZnrc. These images were registered using two registration software packages: VelocityAI and Elastix. With the resultant displacement vector fields (DVFs), the calculated 3D doses were accumulated using a mass-and energy congruent mapping method and compared to those measured by the TLDs at four typical locations. In the static case, TLD measurements agreed with all the algorithms by 1.8% at the center of the tumor volume and by 4.0% in the penumbra. In the deformable case, the phantom's deformation was reproduced within 1.1 mm. For the 3D dose calculated by Pinnacle, the total dose accumulated with the Elastix DVF agreed well to the TLD measurements with their differences <2.5% at four measured locations. When the VelocityAI DVF was used, their difference increased up to 11.8%. For the 3D dose calculated by EGSnrc/DOSXYZnrc, the total doses accumulated with the two DVFs were within 5.7% of the TLD measurements which are slightly over the rate of 5% for clinical acceptance. The detector-embedded deformable phantom allows radiation dose to be measured in a dynamic environment, similar to deforming lung tissues, supporting

  11. Development of a deformable dosimetric phantom to verify dose accumulation algorithms for adaptive radiotherapy

    PubMed Central

    Zhong, Hualiang; Adams, Jeffrey; Glide-Hurst, Carri; Zhang, Hualin; Li, Haisen; Chetty, Indrin J.

    2016-01-01

    Adaptive radiotherapy may improve treatment outcomes for lung cancer patients. Because of the lack of an effective tool for quality assurance, this therapeutic modality is not yet accepted in clinic. The purpose of this study is to develop a deformable physical phantom for validation of dose accumulation algorithms in regions with heterogeneous mass. A three-dimensional (3D) deformable phantom was developed containing a tissue-equivalent tumor and heterogeneous sponge inserts. Thermoluminescent dosimeters (TLDs) were placed at multiple locations in the phantom each time before dose measurement. Doses were measured with the phantom in both the static and deformed cases. The deformation of the phantom was actuated by a motor driven piston. 4D computed tomography images were acquired to calculate 3D doses at each phase using Pinnacle and EGSnrc/DOSXYZnrc. These images were registered using two registration software packages: VelocityAI and Elastix. With the resultant displacement vector fields (DVFs), the calculated 3D doses were accumulated using a mass-and energy congruent mapping method and compared to those measured by the TLDs at four typical locations. In the static case, TLD measurements agreed with all the algorithms by 1.8% at the center of the tumor volume and by 4.0% in the penumbra. In the deformable case, the phantom's deformation was reproduced within 1.1 mm. For the 3D dose calculated by Pinnacle, the total dose accumulated with the Elastix DVF agreed well to the TLD measurements with their differences <2.5% at four measured locations. When the VelocityAI DVF was used, their difference increased up to 11.8%. For the 3D dose calculated by EGSnrc/DOSXYZnrc, the total doses accumulated with the two DVFs were within 5.7% of the TLD measurements which are slightly over the rate of 5% for clinical acceptance. The detector-embedded deformable phantom allows radiation dose to be measured in a dynamic environment, similar to deforming lung tissues, supporting

  12. Investigation of pulsed low dose rate radiotherapy using dynamic arc delivery techniques

    NASA Astrophysics Data System (ADS)

    Ma, C.-M.; Lin, M. H.; Dai, X. F.; Koren, Sion; Klayton, T.; Wang, L.; Li, J. S.; Chen, L.; Price, R. A.

    2012-07-01

    There has been no consensus standard of care to treat recurrent cancer patients who have previously been irradiated. Pulsed low dose rate (PLDR) external beam radiotherapy has the potential to reduce normal tissue toxicities while still providing significant tumor control for recurrent cancers. This work investigates the dosimetry feasibility of PLDR treatment using dynamic arc delivery techniques. Five treatment sites were investigated in this study including breast, pancreas, prostate, head and neck, and lung. Dynamic arc plans were generated using the Varian Eclipse system and the RapidArc delivery technique with 6 and 10 MV photon beams. Each RapidArc plan consisted of two full arcs and the plan was delivered five times to achieve a daily dose of 200 cGy. The dosimetry requirement was to deliver approximately 20 cGy/arc with a 3 min interval to achieve an effective dose rate of 6.7 cGy min-1. Monte Carlo simulations were performed to calculate the actual dose delivered to the planning target volume (PTV) per arc taking into account beam attenuation/scattering and intensity modulation. The maximum, minimum and mean doses to the PTV were analyzed together with the dose volume histograms and isodose distributions. The dose delivery for the five plans was validated using solid water phantoms inserted with an ionization chamber and film, and a cylindrical detector array. Two intensity-modulated arcs were used to efficiently deliver the PLDR plans that provided conformal dose distributions for treating complex recurrent cancers. For the five treatment sites, the mean PTV dose ranged from 18.9 to 22.6 cGy/arc. For breast, the minimum and maximum PTV dose was 8.3 and 35.2 cGy/arc, respectively. The PTV dose varied between 12.9 and 27.5 cGy/arc for pancreas, 12.6 and 28.3 cGy/arc for prostate, 12.1 and 30.4 cGy/arc for H&N, and 16.2 and 27.6 cGy/arc for lung. Advanced radiation therapy can provide superior target coverage and normal tissue sparing for PLDR

  13. Image-Guided Robotic Stereotactic Body Radiation Therapy for Liver Metastases: Is There a Dose Response Relationship?

    SciTech Connect

    Vautravers-Dewas, Claire; Dewas, Sylvain; Bonodeau, Francois; Adenis, Antoine; Lacornerie, Thomas; Penel, Nicolas; Lartigau, Eric; Mirabel, Xavier

    2011-11-01

    Purpose: To evaluate the outcome, tolerance, and toxicity of stereotactic body radiotherapy, using image-guided robotic radiation delivery, for the treatment of patients with unresectable liver metastases. Methods and Material: Patients were treated with real-time respiratory tracking between July 2007 and April 2009. Their records were retrospectively reviewed. Metastases from colorectal carcinoma and other primaries were not necessarily confined to liver. Toxicity was evaluated using National Cancer Institute Common Criteria for Adverse Events version 3.0. Results: Forty-two patients with 62 metastases were treated with two dose levels of 40 Gy in four Dose per Fraction (23) and 45 Gy in three Dose per Fraction (13). Median follow-up was 14.3 months (range, 3-23 months). Actuarial local control for 1 and 2 years was 90% and 86%, respectively. At last follow-up, 41 (66%) complete responses and eight (13%) partial responses were observed. Five lesions were stable. Nine lesions (13%) were locally progressed. Overall survival was 94% at 1 year and 48% at 2 years. The most common toxicity was Grade 1 or 2 nausea. One patient experienced Grade 3 epidermitis. The dose level did not significantly contribute to the outcome, toxicity, or survival. Conclusion: Image-guided robotic stereotactic body radiation therapy is feasible, safe, and effective, with encouraging local control. It provides a strong alternative for patients who cannot undergo surgery.

  14. GPU-based fast Monte Carlo simulation for radiotherapy dose calculation.

    PubMed

    Jia, Xun; Gu, Xuejun; Graves, Yan Jiang; Folkerts, Michael; Jiang, Steve B

    2011-11-21

    Monte Carlo (MC) simulation is commonly considered to be the most accurate dose calculation method in radiotherapy. However, its efficiency still requires improvement for many routine clinical applications. In this paper, we present our recent progress toward the development of a graphics processing unit (GPU)-based MC dose calculation package, gDPM v2.0. It utilizes the parallel computation ability of a GPU to achieve high efficiency, while maintaining the same particle transport physics as in the original dose planning method (DPM) code and hence the same level of simulation accuracy. In GPU computing, divergence of execution paths between threads can considerably reduce the efficiency. Since photons and electrons undergo different physics and hence attain different execution paths, we use a simulation scheme where photon transport and electron transport are separated to partially relieve the thread divergence issue. A high-performance random number generator and a hardware linear interpolation are also utilized. We have also developed various components to handle the fluence map and linac geometry, so that gDPM can be used to compute dose distributions for realistic IMRT or VMAT treatment plans. Our gDPM package is tested for its accuracy and efficiency in both phantoms and realistic patient cases. In all cases, the average relative uncertainties are less than 1%. A statistical t-test is performed and the dose difference between the CPU and the GPU results is not found to be statistically significant in over 96% of the high dose region and over 97% of the entire region. Speed-up factors of 69.1 ∼ 87.2 have been observed using an NVIDIA Tesla C2050 GPU card against a 2.27 GHz Intel Xeon CPU processor. For realistic IMRT and VMAT plans, MC dose calculation can be completed with less than 1% standard deviation in 36.1 ∼ 39.6 s using gDPM. PMID:22016026

  15. Dose Escalation of Whole-Brain Radiotherapy for Brain Metastases From Melanoma

    SciTech Connect

    Rades, Dirk; Heisterkamp, Christine; Huttenlocher, Stefan; Bohlen, Guenther; Dunst, Juergen; Haatanen, Tiina; Schild, Steven E.

    2010-06-01

    Purpose: The majority of patients with brain metastases from melanoma receive whole-brain radiotherapy (WBRT). However, the results are poor. Hypofractionation regimens failed to improve the outcome of these patients. This study investigates a potential benefit from escalation of the WBRT dose beyond the 'standard' regimen 30 Gy in 10 fractions (10x3 Gy). Methods and Materials: Data from 51 melanoma patients receiving WBRT alone were retrospectively analyzed. A dosage of 10x3 Gy (n = 33) was compared with higher doses including 40 Gy/20 fractions (n = 11) and 45 Gy/15 fractions (n = 7) for survival (OS) and local (intracerebral) control (LC). Additional potential prognostic factors were evaluated: age, gender, performance status, number of metastases, extracerebral metastases, and recursive partitioning analysis (RPA) class. Results: At 6 months, OS rates were 27% after 10x3 Gy and 50% after higher doses (p = 0.009). The OS rates at 12 months were 4% and 20%. On multivariate analysis, higher WBRT doses (p = 0.010), fewer than four brain metastases (p = 0.012), no extracerebral metastases (p = 0.006), and RPA class 1 (p = 0.005) were associated with improved OS. The LC rates at 6 months were 23% after 10x3 Gy and 50% after higher doses (p = 0.021). The LC rates at 12 months were 0% and 13%. On multivariate analysis, higher WBRT doses (p = 0.020) and fewer than brain metastases (p = 0.002) were associated with better LC. Conclusions: Given the limitations of a retrospective study, the findings suggest that patients with brain metastases from melanoma receiving WBRT alone may benefit from dose escalation beyond 10x3 Gy. The hypothesis generated by this study must be confirmed in a randomized trial stratifying for significant prognostic factors.

  16. Pre-treatment radiotherapy dose verification using Monte Carlo doselet modulation in a spherical phantom

    NASA Astrophysics Data System (ADS)

    Townson, Reid W.; Zavgorodni, Sergei

    2014-04-01

    Due to the increasing complexity of radiotherapy delivery, accurate dose verification has become an essential part of the clinical treatment process. The purpose of this work was to develop a pre-treatment verification technique capable of quickly reconstructing 3D dose distributions from both coplanar and non-coplanar treatments. For each treatment field, electronic portal images were taken in non-transmission mode (with no patient in the beam) allowing the derivation of the delivered fluence maps. The dose reconstruction was then performed in a spherical water phantom by modulating and summing the Monte Carlo (MC) doselets, defined on a spherical co-ordinate system, and pre-calculated from azimuthally symmetric fluence above the jaws. The technique, called the spherical doselet modulation (SDM) method, essentially eliminates the statistical uncertainty of the MC dose calculations by exploiting the azimuthal symmetry in both a patient-independent phase-space and in a virtual spherical water phantom. For example, this symmetry allowed the number of doselets necessary for dose reconstruction to be reduced by a factor of ˜250. In this work, only 51 radially binned doselets were used (each generated from all particles in a given annulus of the phase-space, azimuthally redistributed into a small cylindrical sector). The SDM method mitigates the most computationally intensive part of this type of dose reconstruction--reading, weighting and summing dose matrices. The accuracy of the system was tested against MC calculations as well as our previously reported phase-space modulation method, using a series of open field and IMRT cases. The mean chi- and gamma-test 3%/3 mm success rates of the SDM method were 98.6% and 99.5%, respectively, when compared to full MC simulation. The total calculation time was 96 s per treatment field on a single processor core.

  17. Low or High Fractionation Dose {beta}-Radiotherapy for Pterygium? A Randomized Clinical Trial

    SciTech Connect

    Viani, Gustavo Arruda; De Fendi, Ligia Issa; Fonseca, Ellen Carrara; Stefano, Eduardo Jose

    2012-02-01

    Purpose: Postoperative adjuvant treatment using {beta}-radiotherapy (RT) is a proven technique for reducing the recurrence of pterygium. A randomized trial was conducted to determine whether a low fractionation dose of 2 Gy within 10 fractions would provide local control similar to that after a high fractionation dose of 5 Gy within 7 fractions for surgically resected pterygium. Methods: A randomized trial was conducted in 200 patients (216 pterygia) between February 2006 and July 2007. Only patients with fresh pterygium resected using a bare sclera method and given RT within 3 days were included. Postoperative RT was delivered using a strontium-90 eye applicator. The pterygia were randomly treated using either 5 Gy within 7 fractions (Group 1) or 2 Gy within 10 fractions (Group 2). The local control rate was calculated from the date of surgery. Results: Of the 216 pterygia included, 112 were allocated to Group 1 and 104 to Group 2. The 3-year local control rate for Groups 1 and 2 was 93.8% and 92.3%, respectively (p = .616). A statistically significant difference for cosmetic effect (p = .034), photophobia (p = .02), irritation (p = .001), and scleromalacia (p = .017) was noted in favor of Group 2. Conclusions: No better local control rate for postoperative pterygium was obtained using high-dose fractionation vs. low-dose fractionation. However, a low-dose fractionation schedule produced better cosmetic effects and resulted in fewer symptoms than high-dose fractionation. Moreover, pterygia can be safely treated in terms of local recurrence using RT schedules with a biologic effective dose of 24-52.5 Gy{sub 10.}.

  18. SU-E-J-83: CBCT Based Rectum and Bladder Dose Tracking in the Prostate Radiotherapy

    SciTech Connect

    Chen, Z; Wang, J; Yang, Z; Hu, W

    2015-06-15

    Purpose: The aim of this study is to monitor the volume changes of bladder and rectum and evaluate the dosimetric changes of bladder and rectum using daily cone-beam CT for prostate radiotherapy. Methods: The data of this study were obtained from 12 patients, totally 222 CBCTs. All the volume of the bladder and the rectum on the CBCT were normalized to the bladder and the rectum on their own original CT to monitory the volume changes. To evaluate dose delivered to the OARs, volumes that receive 70Gy (V70Gy), 60Gy, 50Gy, 40Gy and 30Gy are calculated for the bladder and the rectum, V20Gy and V10Gy for rectum additionally. And the deviation of the mean dose to the bladder and the rectum are also chosen as the evaluation parameter. Linear regression analysis was performed to identify the mean dose change of the volume change using SPSS 19. Results: The results show that the variances of the normalize volume of the bladder and the rectum are 0.15–0.58 and 0.13–0.50. The variances of V70Gy, V60Gy, V50Gy, V40Gy and V30Gy of bladder are bigger than rectum for 11 patients. The linear regression analysis indicated a negative correlation between the volume and the mean dose of the bladder (p < 0.05). A 10% increase in bladder volume will cause 5.1% (±4.3%) reduction in mean dose. Conclusion: The bladder volume change is more significant than that for rectum for the prostate cancer patient. The volume changes of rectum are not significant except air gap in the rectum. Bladder volume varies will cause significant dose change. The bladder volume monitoring before fractional treatment delivery would be crucial for accuracy dose delivery.

  19. Tumor Volume-Adapted Dosing in Stereotactic Ablative Radiotherapy of Lung Tumors

    SciTech Connect

    Trakul, Nicholas; Chang, Christine N.; Harris, Jeremy; Chapman, Christopher; Rao, Aarti; Shen, John; Quinlan-Davidson, Sean; Filion, Edith J.; Wakelee, Heather A.; Colevas, A. Dimitrios; Whyte, Richard I.; and others

    2012-09-01

    Purpose: Current stereotactic ablative radiotherapy (SABR) protocols for lung tumors prescribe a uniform dose regimen irrespective of tumor size. We report the outcomes of a lung tumor volume-adapted SABR dosing strategy. Methods and Materials: We retrospectively reviewed the outcomes in 111 patients with a total of 138 primary or metastatic lung tumors treated by SABR, including local control, regional control, distant metastasis, overall survival, and treatment toxicity. We also performed subset analysis on 83 patients with 97 tumors treated with a volume-adapted dosing strategy in which small tumors (gross tumor volume <12 mL) received single-fraction regimens with biologically effective doses (BED) <100 Gy (total dose, 18-25 Gy) (Group 1), and larger tumors (gross tumor volume {>=}12 mL) received multifraction regimens with BED {>=}100 Gy (total dose, 50-60 Gy in three to four fractions) (Group 2). Results: The median follow-up time was 13.5 months. Local control for Groups 1 and 2 was 91.4% and 92.5%, respectively (p = 0.24) at 12 months. For primary lung tumors only (excluding metastases), local control was 92.6% and 91.7%, respectively (p = 0.58). Regional control, freedom from distant metastasis, and overall survival did not differ significantly between Groups 1 and 2. Rates of radiation pneumonitis, chest wall toxicity, and esophagitis were low in both groups, but all Grade 3 toxicities developed in Group 2 (p = 0.02). Conclusion: A volume-adapted dosing approach for SABR of lung tumors seems to provide excellent local control for both small- and large-volume tumors and may reduce toxicity.

  20. Dosimetric characteristics of the Leipzig surface applicators used in the high dose rate brachy radiotherapy

    SciTech Connect

    Niu Hongquan; Hsi, Wen C.; Chu, James C.H.; Kirk, Michael C.; Kouwenhoven, Erik

    2004-12-01

    The nucletron Leipzig applicator is designed for (HDR) {sup 192}Ir brachy radiotherapy of surface lesions. The dosimetric characteristics of this applicator were investigated using simulation method based on Monte Carlo N-particle (MCNP) code and phantom measurements. The simulation method was validated by comparing calculated dose rate distributions of nucletron microSelectron HDR {sup 192}Ir source against published data. Radiochromic films and metal-oxide-semiconductor field-effect transistor (MOSFET) detectors were used for phantom measurements. The double exposure technique, correcting the nonuniform film sensitivity, was applied in the film dosimetry. The linear fit of multiple readings with different irradiation times performed for each MOSFET detector measurement was used to obtain the dose rate of each measurement and to correct the source transit-time error. The film and MOSFET measurements have uncertainties of 3%-7% and 3%-5%, respectively. The dose rate distributions of the Leipzig applicator with 30 mm opening calculated by the validated MC method were verified by measurements of film and MOSFET detectors. Calculated two-dimensional planar dose rate distributions show similar patterns as the film measurement. MC calculated dose rate at a reference point defined at depth 5 mm on the applicator's central axis is 7% lower than the film and 3% higher than the MOSFET measurements. The dose rate of a Leipzig applicator with 30 mm opening at reference point is 0.241{+-}3% cGy h{sup -1} U{sup -1}. The MC calculated depth dose rates and profiles were tabulated for clinic use.

  1. High-dose-rate Three-dimensional Conformal Radiotherapy Combined with Active Breathing Control for Stereotactic Body Radiotherapy of Early-stage Non-small-cell Lung Cancer.

    PubMed

    Wang, Ruozheng; Yin, Yong; Qin, Yonghui; Yu, Jinming

    2015-12-01

    The purpose of this study was to evaluate the feasibility and benefits of using high-dose-rate three-dimensional conformal radiotherapy (3D-CRT) combined with active breathing control (ABC) for stereotactic body radiotherapy (SBRT) of patients with early-stage non-small-cell lung cancer (NSCLC). Eight patients with early-stage NSCLC underwent CT scans under standard free-breathing (FB) and moderately deep inspiration breath-hold (mDIBH) with ABC. Two high-dose-rate 3D-CRT plans (1000 Mu/min) were designed based on the CT scans with FB and mDIBH. The maximal dose (D1%), minimal dose (D99%), conformity index (CI), and homogeneity index (HI) of the planning target volume (PTV), and dose-volume indices of the organs at risk between each plan were compared. The mean PTV volume decreased from 158.04 cm(3) with FB to 76.90 cm(3) with mDIBH (p < 0.05). When mDIBH was used, increases in the affected lung volume (by 47%), contralateral lung volume (by 55%), and total lung volume (by 50%) were observed compared to FB (p < 0.05). The V5-V40 of the affected lung (Vx represented the percentage volume of organs receiving at least the x Gy), V5-V40 and the mean dose for the total lung, V5-V40 and mean dose of the chest wall, and the maximum dose of the spinal cord were less for mDIBH than FB (p < 0.05). There were no significant differences in CI, HI, D1%, or D99% for the PTV between the plans. In conclusion, high-dose-rate 3D-CRT combined with ABC reduced the radiation dose to the lungs and chest wall without affecting the dose distribution in SBRT of early-stage NSCLC patients. PMID:24988055

  2. Fast CPU-based Monte Carlo simulation for radiotherapy dose calculation

    NASA Astrophysics Data System (ADS)

    Ziegenhein, Peter; Pirner, Sven; Kamerling, Cornelis Ph; Oelfke, Uwe

    2015-08-01

    Monte-Carlo (MC) simulations are considered to be the most accurate method for calculating dose distributions in radiotherapy. Its clinical application, however, still is limited by the long runtimes conventional implementations of MC algorithms require to deliver sufficiently accurate results on high resolution imaging data. In order to overcome this obstacle we developed the software-package PhiMC, which is capable of computing precise dose distributions in a sub-minute time-frame by leveraging the potential of modern many- and multi-core CPU-based computers. PhiMC is based on the well verified dose planning method (DPM). We could demonstrate that PhiMC delivers dose distributions which are in excellent agreement to DPM. The multi-core implementation of PhiMC scales well between different computer architectures and achieves a speed-up of up to 37× compared to the original DPM code executed on a modern system. Furthermore, we could show that our CPU-based implementation on a modern workstation is between 1.25× and 1.95× faster than a well-known GPU implementation of the same simulation method on a NVIDIA Tesla C2050. Since CPUs work on several hundreds of GB RAM the typical GPU memory limitation does not apply for our implementation and high resolution clinical plans can be calculated.

  3. Prognostic factors of inoperable localized lung cancer treated by high dose radiotherapy

    SciTech Connect

    Schaake-Koning, C.S.; Schuster-Uitterhoeve, L.; Hart, G.; Gonzalez, D.G.

    1983-07-01

    A retrospective study was made of the results of high dose radiotherapy (greater than or equal to 50 Gy) given to 171 patients with inoperable, intrathoracic non small cell lung cancer from January 1971-April 1973. Local control was dependent on the total tumor dose: after one year local control was 63% for patients treated with >65 Gy, the two year local control was 35%. If treated with <65 Gy the one year local control was less than or equal to 40%. Tumor doses correlated with the size of the booster field. If the size of the booster field was <100 cm/sup 2/, the one year local control was 72%; the two year local control was 44%. Local control was also influenced by the performance status, by the localization of the primary tumor in the left upper lobe and in the periphery of the lung. Local control for tumors in the left upper lobe and in the periphery of the lung was about 70% after one year, and about 40% after two years. The one and two years survival results were correlated with the factors influencing local control. The dose factor, the localization factors and the performance influenced local control independently. Tumors localized in the left upper lobe did metastasize less than tumors in the lower lobe, or in a combination of the two. This was not true for the right upper lobe. No correlation between the TNM system, pathology and the prognosis was found.

  4. Full-Dose Gemcitabine and Concurrent Radiotherapy for Unresectable Pancreatic Cancer

    SciTech Connect

    Murphy, James D.; Adusumilli, Saroja; Griffith, Kent A.; Ray, Michael E.; Zalupski, Mark M.; Lawrence, Theodore S.; Ben-Josef, Edgar . E-mail: edgarb@med.umich.edu

    2007-07-01

    Purpose: Full-dose gemcitabine and concurrent radiotherapy is a promising treatment approach in unresectable pancreatic cancer. This study was conducted to assess the pattern of failure and toxicity associated with the use of conformal treatment volumes, omitting prophylactic lymph node irradiation. Methods and Materials: Seventy-four patients with locally advanced pancreatic cancer were treated between 1997 and 2005 with full-dose (1000 mg/m{sup 2}, Days 1, 8, and 15) gemcitabine and concurrent radiotherapy (36 Gy [median] in 15 daily fractions). The planning target volume (PTV) was limited to the gross tumor volume (GTV) plus 1-cm margin. Patient computed tomography (CT) scans were systematically reviewed to determine the pattern of failure. Kaplan-Meier and Cox-regression models were used to analyze freedom from local progression (FFLP), distant failure, overall survival (OS), and toxicity. Results: With a median follow-up of 10.6 months (20.6 months in living patients), the 1-year and 2-year FFLP rates were 64% and 38%, respectively. Four patients (5%) failed in the peripancreatic lymph nodes (3 in-field and 1 marginal failure). Median OS was 11.2 months. Analyzed as a time-dependent covariate, local failure was a significant predictor of OS (p = 0.0074). Sixteen patients (22%) had significant gastrointestinal (GI) toxicity ({>=} Grade 3). PTV correlated with significant GI toxicity (p = 0.007). Conclusions: Freedom from local progression in unresectable pancreatic cancer is suboptimal. In conjunction with full-dose gemcitabine, the use of conformal fields encompassing only the GTV helps reduce toxicity and does not result in marginal failures. Our findings provide rationale for intensification of local therapy in conjunction with more effective systemic therapy.

  5. Comprehensive analysis of electron beam central axis dose for a radiotherapy linear accelerator.

    PubMed

    Shiu, A S; Tung, S S; Nyerick, C E; Ochran, T G; Otte, V A; Boyer, A L; Hogstrom, K R

    1994-04-01

    This work evaluates the application of AAPM task group 25 (TG25) methodology for determination of central axis depth dose for a radiotherapy linear accelerator, whose dual scattering foil system and applicators were recently modified. The percent depth dose (%DD) and the dose output factor have been measured for square and rectangular fields at 100- and 110-cm source-to-surface distance (SSDs). At 100-cm SSD, results showed that %DD for a specific energy and field size can vary with applicator, the largest variation being for the 20-MeV, 10 x 10-cm field where a spread of +/- 2.5% or +/- 3 mm about the mean %DD is observed. The square-root method determines rectangular field %DD within 1%. Output factors for rectangular fields are calculated from square field values more accurately using a square-root method than the equivalent-square method recommended by TG25. At 110-cm SSD, the %DD calculated from that at 100-cm SSD using an inverse square factor does not agree with measured values for all fields. The maximum difference observed for the 20-MeV, 6 x 6-cm field was 5.5% or 10 mm. Output data at the 110-cm SSD show that the square-root method is suitable for determination of the air-gap correction factors of rectangular fields. In summary, the recommendations of TG25 work reasonably well for central axis electron beam dosimetry for this version of a radiotherapy linear accelerator, except in limited cases where applicator-scattered electrons apparently cause minor but clinically significant discrepancies. PMID:8058023

  6. NBN gain is predictive for adverse outcome following image-guided radiotherapy for localized prostate cancer.

    PubMed

    Berlin, Alejandro; Lalonde, Emilie; Sykes, Jenna; Zafarana, Gaetano; Chu, Kenneth C; Ramnarine, Varune R; Ishkanian, Adrian; Sendorek, Dorota H S; Pasic, Ivan; Lam, Wan L; Jurisica, Igor; van der Kwast, Theo; Milosevic, Michael; Boutros, Paul C; Bristow, Robert G

    2014-11-30

    Despite the use of clinical prognostic factors (PSA, T-category and Gleason score), 20-60% of localized prostate cancers (PCa) fail primary local treatment. Herein, we determined the prognostic importance of main sensors of the DNA damage response (DDR): MRE11A, RAD50, NBN, ATM, ATR and PRKDC. We studied copy number alterations in DDR genes in localized PCa treated with image-guided radiotherapy (IGRT; n=139) versus radical prostatectomy (RadP; n=154). In both cohorts, NBN gains were the most frequent genomic alteration (14.4 and 11% of cases, respectively), and were associated with overall tumour genomic instability (p<0.0001). NBN gains were the only significant predictor of 5yrs biochemical relapse-free rate (bRFR) following IGRT (46% versus 77%; p=0.00067). On multivariate analysis, NBN gain remained a significant independent predictor of bRFR after adjusting for known clinical prognostic variables (HR=3.28, 95% CI 1.56-6.89, Wald p-value=0.0017). No DDR-sensing gene was prognostic in the RadP cohort. In vitro studies correlated NBN gene overexpression with PCa cells radioresistance. In conclusion, NBN gain predicts for decreased bRFR in IGRT, but not in RadP patients. If validated independently, Nibrin gains may be the first PCa predictive biomarker to facilitate local treatment decisions using precision medicine approaches with surgery or radiotherapy. PMID:25415046

  7. Four-dimensional dose evaluation using deformable image registration in radiotherapy for liver cancer

    SciTech Connect

    Hoon Jung, Sang; Min Yoon, Sang; Ho Park, Sung; Cho, Byungchul; Won Park, Jae; Jung, Jinhong; Park, Jin-hong; Hoon Kim, Jong; Do Ahn, Seung

    2013-01-15

    Purpose: In order to evaluate the dosimetric impact of respiratory motion on the dose delivered to the target volume and critical organs during free-breathing radiotherapy, a four-dimensional dose was evaluated using deformable image registration (DIR). Methods: Four-dimensional computed tomography (4DCT) images were acquired for 11 patients who were treated for liver cancer. Internal target volume-based treatment planning and dose calculation (3D dose) were performed using the end-exhalation phase images. The four-dimensional dose (4D dose) was calculated based on DIR of all phase images from 4DCT to the planned image. Dosimetric parameters from the 4D dose, were calculated and compared with those from the 3D dose. Results: There was no significant change of the dosimetric parameters for gross tumor volume (p > 0.05). The increase D{sub mean} and generalized equivalent uniform dose (gEUD) for liver were by 3.1%{+-} 3.3% (p= 0.003) and 2.8%{+-} 3.3% (p= 0.008), respectively, and for duodenum, they were decreased by 15.7%{+-} 11.2% (p= 0.003) and 15.1%{+-} 11.0% (p= 0.003), respectively. The D{sub max} and gEUD for stomach was decreased by 5.3%{+-} 5.8% (p= 0.003) and 9.7%{+-} 8.7% (p= 0.003), respectively. The D{sub max} and gEUD for right kidney was decreased by 11.2%{+-} 16.2% (p= 0.003) and 14.9%{+-} 16.8% (p= 0.005), respectively. For left kidney, D{sub max} and gEUD were decreased by 11.4%{+-} 11.0% (p= 0.003) and 12.8%{+-} 12.1% (p= 0.005), respectively. The NTCP values for duodenum and stomach were decreased by 8.4%{+-} 5.8% (p= 0.003) and 17.2%{+-} 13.7% (p= 0.003), respectively. Conclusions: The four-dimensional dose with a more realistic dose calculation accounting for respiratory motion revealed no significant difference in target coverage and potentially significant change in the physical and biological dosimetric parameters in normal organs during free-breathing treatment.

  8. SU-E-T-43: Analytical Model for Photon Peripheral Dose in Radiotherapy Treatments

    SciTech Connect

    Nieto, B Sanchez; El far, R; Romero-Exposito, M; Lagares, J; Mateo, JC; Terron, JA; Irazola, L; Sanchez-Doblado, F

    2014-06-01

    Purpose: The higher survival rate of radiotherapy patients entails a growing concern on second cancers associated to peripheral doses. Currently, dosimetry of out-of field doses is still under development. Our group has developed a methodology to estimate neutron equivalent dose in organs (1,2). We aimed to propose a model to estimate out-of-field photon doses in isocentric treatments from basic clinical data. Methods: The proposed function models the dose as the sum of leakage and scatter terms. The latter is modeled as a virtual source at the collimator, which suffers from attenuation in air and tissue, corrected by the inverse-square-law. The model was parameterized using experimental measurements with TLD700 chips placed inside an anthropomorphic phantom (6–18MV) irradiated with conformal and modulated techniques in Elekta, Siemens and Varian linacs. This model provides photon dose at a point as a function of clinical parameters as prescription dose/UM, PTV volume, distance to the field edge, height of the MLC leaves and distance from the the MLC to the isocenter. Model was tested against independent measurements (TLD100) for a VMAT treatment on a Elekta. Dose to organs is modeled from dose to points along the head-to-feet axis of the organ of a “standard man” escalated by patient height. Results: Our semi-empirical model depends on 3 given parameters (leakage parameter can be individualized). A novelty of our model, over other models (e.g., PERIDOSE), arises from its applicability to any technique (independently of the number of MU needed to deliver a dose). Differences between predictions and measurements were < 0.005mSv/UM. Conclusion: We have proposed a unique model which successfully account for photon peripheral organ dose. This model can be applied in the day-to-day clinic as it only needs a few basic parameters which are readily accessible.1. Radiother. Oncol. 107:234–243, 2013. 2. Phys. Med. Biol. 57:6167–6191, 2012.

  9. Dose variations caused by setup errors in intracranial stereotactic radiotherapy: a PRESAGE study.

    PubMed

    Teng, Kieyin; Gagliardi, Frank; Alqathami, Mamdooh; Ackerly, Trevor; Geso, Moshi

    2014-01-01

    Stereotactic radiotherapy (SRT) requires tight margins around the tumor, thus producing a steep dose gradient between the tumor and the surrounding healthy tissue. Any setup errors might become clinically significant. To date, no study has been performed to evaluate the dosimetric variations caused by setup errors with a 3-dimensional dosimeter, the PRESAGE. This research aimed to evaluate the potential effect that setup errors have on the dose distribution of intracranial SRT. Computed tomography (CT) simulation of a CIRS radiosurgery head phantom was performed with 1.25-mm slice thickness. An ideal treatment plan was generated using Brainlab iPlan. A PRESAGE was made for every treatment with and without errors. A prescan using the optical CT scanner was carried out. Before treatment, the phantom was imaged using Brainlab ExacTrac. Actual radiotherapy treatments with and without errors were carried out with the Novalis treatment machine. Postscan was performed with an optical CT scanner to analyze the dose irradiation. The dose variation between treatments with and without errors was determined using a 3-dimensional gamma analysis. Errors are clinically insignificant when the passing ratio of the gamma analysis is 95% and above. Errors were clinically significant when the setup errors exceeded a 0.7-mm translation and a 0.5° rotation. The results showed that a 3-mm translation shift in the superior-inferior (SI), right-left (RL), and anterior-posterior (AP) directions and 2° couch rotation produced a passing ratio of 53.1%. Translational and rotational errors of 1.5mm and 1°, respectively, generated a passing ratio of 62.2%. Translation shift of 0.7mm in the directions of SI, RL, and AP and a 0.5° couch rotation produced a passing ratio of 96.2%. Preventing the occurrences of setup errors in intracranial SRT treatment is extremely important as errors greater than 0.7mm and 0.5° alter the dose distribution. The geometrical displacements affect dose delivery to

  10. Dose variations caused by setup errors in intracranial stereotactic radiotherapy: A PRESAGE study

    SciTech Connect

    Teng, Kieyin; Gagliardi, Frank; Alqathami, Mamdooh; Ackerly, Trevor; Geso, Moshi

    2014-01-01

    Stereotactic radiotherapy (SRT) requires tight margins around the tumor, thus producing a steep dose gradient between the tumor and the surrounding healthy tissue. Any setup errors might become clinically significant. To date, no study has been performed to evaluate the dosimetric variations caused by setup errors with a 3-dimensional dosimeter, the PRESAGE. This research aimed to evaluate the potential effect that setup errors have on the dose distribution of intracranial SRT. Computed tomography (CT) simulation of a CIRS radiosurgery head phantom was performed with 1.25-mm slice thickness. An ideal treatment plan was generated using Brainlab iPlan. A PRESAGE was made for every treatment with and without errors. A prescan using the optical CT scanner was carried out. Before treatment, the phantom was imaged using Brainlab ExacTrac. Actual radiotherapy treatments with and without errors were carried out with the Novalis treatment machine. Postscan was performed with an optical CT scanner to analyze the dose irradiation. The dose variation between treatments with and without errors was determined using a 3-dimensional gamma analysis. Errors are clinically insignificant when the passing ratio of the gamma analysis is 95% and above. Errors were clinically significant when the setup errors exceeded a 0.7-mm translation and a 0.5° rotation. The results showed that a 3-mm translation shift in the superior-inferior (SI), right-left (RL), and anterior-posterior (AP) directions and 2° couch rotation produced a passing ratio of 53.1%. Translational and rotational errors of 1.5 mm and 1°, respectively, generated a passing ratio of 62.2%. Translation shift of 0.7 mm in the directions of SI, RL, and AP and a 0.5° couch rotation produced a passing ratio of 96.2%. Preventing the occurrences of setup errors in intracranial SRT treatment is extremely important as errors greater than 0.7 mm and 0.5° alter the dose distribution. The geometrical displacements affect dose delivery

  11. SU-E-T-501: Normal Tissue Toxicities of Pulsed Low Dose Rate Radiotherapy and Conventional Radiotherapy: An in Vivo Total Body Irradiation Study

    SciTech Connect

    Cvetkovic, D; Zhang, P; Wang, B; Chen, L; Ma, C

    2014-06-01

    Purpose: Pulsed low dose rate radiotherapy (PLDR) is a re-irradiation technique for therapy of recurrent cancers. We have previously shown a significant difference in the weight and survival time between the mice treated with conventional radiotherapy (CRT) and PLDR using total body irradiation (TBI). The purpose of this study was to investigate the in vivo effects of PLDR on normal mouse tissues.Materials and Methods: Twenty two male BALB/c nude mice, 4 months of age, were randomly assigned into a PLDR group (n=10), a CRT group (n=10), and a non-irradiated control group (n=2). The Siemens Artiste accelerator with 6 MV photon beams was used. The mice received a total of 18Gy in 3 fractions with a 20day interval. The CRT group received the 6Gy dose continuously at a dose rate of 300 MU/min. The PLDR group was irradiated with 0.2Gyx20 pulses with a 3min interval between the pulses. The mice were weighed thrice weekly and sacrificed 2 weeks after the last treatment. Brain, heart, lung, liver, spleen, gastrointestinal, urinary and reproductive organs, and sternal bone marrow were removed, formalin-fixed, paraffin-embedded and stained with H and E. Morphological changes were observed under a microscope. Results: Histopathological examination revealed atrophy in several irradiated organs. The degree of atrophy was mild to moderate in the PLDR group, but severe in the CRT group. The most pronounced morphological abnormalities were in the immune and hematopoietic systems, namely spleen and bone marrow. Brain hemorrhage was seen in the CRT group, but not in the PLDR group. Conclusions: Our results showed that PLDR induced less toxicity in the normal mouse tissues than conventional radiotherapy for the same dose and regimen. Considering that PLDR produces equivalent tumor control as conventional radiotherapy, it would be a good modality for treatment of recurrent cancers.

  12. Incremental Learning With Selective Memory (ILSM): Towards Fast Prostate Localization for Image Guided Radiotherapy

    PubMed Central

    Gao, Yaozong; Zhan, Yiqiang

    2015-01-01

    Image-guided radiotherapy (IGRT) requires fast and accurate localization of the prostate in 3-D treatment-guided radiotherapy, which is challenging due to low tissue contrast and large anatomical variation across patients. On the other hand, the IGRT workflow involves collecting a series of computed tomography (CT) images from the same patient under treatment. These images contain valuable patient-specific information yet are often neglected by previous works. In this paper, we propose a novel learning framework, namely incremental learning with selective memory (ILSM), to effectively learn the patient-specific appearance characteristics from these patient-specific images. Specifically, starting with a population-based discriminative appearance model, ILSM aims to “personalize” the model to fit patient-specific appearance characteristics. The model is personalized with two steps: backward pruning that discards obsolete population-based knowledge and forward learning that incorporates patient-specific characteristics. By effectively combining the patient-specific characteristics with the general population statistics, the incrementally learned appearance model can localize the prostate of a specific patient much more accurately. This work has three contributions: 1) the proposed incremental learning framework can capture patient-specific characteristics more effectively, compared to traditional learning schemes, such as pure patient-specific learning, population-based learning, and mixture learning with patient-specific and population data; 2) this learning framework does not have any parametric model assumption, hence, allowing the adoption of any discriminative classifier; and 3) using ILSM, we can localize the prostate in treatment CTs accurately (DSC ∼0.89) and fast (∼4 s), which satisfies the real-world clinical requirements of IGRT. PMID:24495983

  13. SU-E-J-191: Motion Prediction Using Extreme Learning Machine in Image Guided Radiotherapy

    SciTech Connect

    Jia, J; Cao, R; Pei, X; Wang, H; Hu, L

    2015-06-15

    Purpose: Real-time motion tracking is a critical issue in image guided radiotherapy due to the time latency caused by image processing and system response. It is of great necessity to fast and accurately predict the future position of the respiratory motion and the tumor location. Methods: The prediction of respiratory position was done based on the positioning and tracking module in ARTS-IGRT system which was developed by FDS Team (www.fds.org.cn). An approach involving with the extreme learning machine (ELM) was adopted to predict the future respiratory position as well as the tumor’s location by training the past trajectories. For the training process, a feed-forward neural network with one single hidden layer was used for the learning. First, the number of hidden nodes was figured out for the single layered feed forward network (SLFN). Then the input weights and hidden layer biases of the SLFN were randomly assigned to calculate the hidden neuron output matrix. Finally, the predicted movement were obtained by applying the output weights and compared with the actual movement. Breathing movement acquired from the external infrared markers was used to test the prediction accuracy. And the implanted marker movement for the prostate cancer was used to test the implementation of the tumor motion prediction. Results: The accuracy of the predicted motion and the actual motion was tested. Five volunteers with different breathing patterns were tested. The average prediction time was 0.281s. And the standard deviation of prediction accuracy was 0.002 for the respiratory motion and 0.001 for the tumor motion. Conclusion: The extreme learning machine method can provide an accurate and fast prediction of the respiratory motion and the tumor location and therefore can meet the requirements of real-time tumor-tracking in image guided radiotherapy.

  14. Voxel-based population analysis for correlating local dose and rectal toxicity in prostate cancer radiotherapy

    NASA Astrophysics Data System (ADS)

    Acosta, Oscar; Drean, Gael; Ospina, Juan D.; Simon, Antoine; Haigron, Pascal; Lafond, Caroline; de Crevoisier, Renaud

    2013-04-01

    The majority of current models utilized for predicting toxicity in prostate cancer radiotherapy are based on dose-volume histograms. One of their main drawbacks is the lack of spatial accuracy, since they consider the organs as a whole volume and thus ignore the heterogeneous intra-organ radio-sensitivity. In this paper, we propose a dose-image-based framework to reveal the relationships between local dose and toxicity. In this approach, the three-dimensional (3D) planned dose distributions across a population are non-rigidly registered into a common coordinate system and compared at a voxel level, therefore enabling the identification of 3D anatomical patterns, which may be responsible for toxicity, at least to some extent. Additionally, different metrics were employed in order to assess the quality of the dose mapping. The value of this approach was demonstrated by prospectively analyzing rectal bleeding (⩾Grade 1 at 2 years) according to the CTCAE v3.0 classification in a series of 105 patients receiving 80 Gy to the prostate by intensity modulated radiation therapy (IMRT). Within the patients presenting bleeding, a significant dose excess (6 Gy on average, p < 0.01) was found in a region of the anterior rectal wall. This region, close to the prostate (1 cm), represented less than 10% of the rectum. This promising voxel-wise approach allowed subregions to be defined within the organ that may be involved in toxicity and, as such, must be considered during the inverse IMRT planning step.

  15. Neutron scattered dose equivalent to a fetus from proton radiotherapy of the mother.

    PubMed

    Mesoloras, Geraldine; Sandison, George A; Stewart, Robert D; Farr, Jonathan B; Hsi, Wen C

    2006-07-01

    Scattered neutron dose equivalent to a representative point for a fetus is evaluated in an anthropomorphic phantom of the mother undergoing proton radiotherapy. The effect on scattered neutron dose equivalent to the fetus of changing the incident proton beam energy, aperture size, beam location, and air gap between the beam delivery snout and skin was studied for both a small field snout and a large field snout. Measurements of the fetus scattered neutron dose equivalent were made by placing a neutron bubble detector 10 cm below the umbilicus of an anthropomorphic Rando phantom enhanced by a wax bolus to simulate a second trimester pregnancy. The neutron dose equivalent in milliSieverts (mSv) per proton treatment Gray increased with incident proton energy and decreased with aperture size, distance of the fetus representative point from the field edge, and increasing air gap. Neutron dose equivalent to the fetus varied from 0.025 to 0.450 mSv per proton Gray for the small field snout and from 0.097 to 0.871 mSv per proton Gray for the large field snout. There is likely to be no excess risk to the fetus of severe mental retardation for a typical proton treatment of 80 Gray to the mother since the scattered neutron dose to the fetus of 69.7 mSv is well below the lower confidence limit for the threshold of 300 mGy observed for the occurrence of severe mental retardation in prenatally exposed Japanese atomic bomb survivors. However, based on the linear no threshold hypothesis, and this same typical treatment for the mother, the excess risk to the fetus of radiation induced cancer death in the first 10 years of life is 17.4 per 10,000 children. PMID:16898451

  16. Voxel-based population analysis for correlating local dose and rectal toxicity in prostate cancer radiotherapy.

    PubMed

    Acosta, Oscar; Drean, Gael; Ospina, Juan D; Simon, Antoine; Haigron, Pascal; Lafond, Caroline; de Crevoisier, Renaud

    2013-04-21

    The majority of current models utilized for predicting toxicity in prostate cancer radiotherapy are based on dose-volume histograms. One of their main drawbacks is the lack of spatial accuracy, since they consider the organs as a whole volume and thus ignore the heterogeneous intra-organ radio-sensitivity. In this paper, we propose a dose-image-based framework to reveal the relationships between local dose and toxicity. In this approach, the three-dimensional (3D) planned dose distributions across a population are non-rigidly registered into a common coordinate system and compared at a voxel level, therefore enabling the identification of 3D anatomical patterns, which may be responsible for toxicity, at least to some extent. Additionally, different metrics were employed in order to assess the quality of the dose mapping. The value of this approach was demonstrated by prospectively analyzing rectal bleeding (≥Grade 1 at 2 years) according to the CTCAE v3.0 classification in a series of 105 patients receiving 80 Gy to the prostate by intensity modulated radiation therapy (IMRT). Within the patients presenting bleeding, a significant dose excess (6 Gy on average, p < 0.01) was found in a region of the anterior rectal wall. This region, close to the prostate (1 cm), represented less than 10% of the rectum. This promising voxel-wise approach allowed subregions to be defined within the organ that may be involved in toxicity and, as such, must be considered during the inverse IMRT planning step. PMID:23528429

  17. Neutron scattered dose equivalent to a fetus from proton radiotherapy of the mother

    SciTech Connect

    Mesoloras, Geraldine; Sandison, George A.; Stewart, Robert D.; Farr, Jonathan B.; Hsi, Wen C.

    2006-07-15

    Scattered neutron dose equivalent to a representative point for a fetus is evaluated in an anthropomorphic phantom of the mother undergoing proton radiotherapy. The effect on scattered neutron dose equivalent to the fetus of changing the incident proton beam energy, aperture size, beam location, and air gap between the beam delivery snout and skin was studied for both a small field snout and a large field snout. Measurements of the fetus scattered neutron dose equivalent were made by placing a neutron bubble detector 10 cm below the umbilicus of an anthropomorphic Rando[reg] phantom enhanced by a wax bolus to simulate a second trimester pregnancy. The neutron dose equivalent in milliSieverts (mSv) per proton treatment Gray increased with incident proton energy and decreased with aperture size, distance of the fetus representative point from the field edge, and increasing air gap. Neutron dose equivalent to the fetus varied from 0.025 to 0.450 mSv per proton Gray for the small field snout and from 0.097 to 0.871 mSv per proton Gray for the large field snout. There is likely to be no excess risk to the fetus of severe mental retardation for a typical proton treatment of 80 Gray to the mother since the scattered neutron dose to the fetus of 69.7 mSv is well below the lower confidence limit for the threshold of 300 mGy observed for the occurrence of severe mental retardation in prenatally exposed Japanese atomic bomb survivors. However, based on the linear no threshold hypothesis, and this same typical treatment for the mother, the excess risk to the fetus of radiation induced cancer death in the first 10 years of life is 17.4 per 10 000 children.

  18. Individualized Dose Prescription for Hypofractionation in Advanced Non-Small-Cell Lung Cancer Radiotherapy: An in silico Trial

    SciTech Connect

    Hoffmann, Aswin L.; Troost, Esther G.C.; Huizenga, Henk; Kaanders, Johannes H.A.M.; Bussink, Johan

    2012-08-01

    Purpose: Local tumor control and outcome remain poor in patients with advanced non-small-cell lung cancer (NSCLC) treated by external beam radiotherapy. We investigated the therapeutic gain of individualized dose prescription with dose escalation based on normal tissue dose constraints for various hypofractionation schemes delivered with intensity-modulated radiation therapy. Methods and Materials: For 38 Stage III NSCLC patients, the dose level of an existing curative treatment plan with standard fractionation (66 Gy) was rescaled based on dose constraints for the lung, spinal cord, esophagus, brachial plexus, and heart. The effect on tumor total dose (TTD) and biologic tumor effective dose in 2-Gy fractions (TED) corrected for overall treatment time (OTT) was compared for isotoxic and maximally tolerable schemes given in 15, 20, and 33 fractions. Rescaling was accomplished by altering the dose per fraction and/or the number of fractions while keeping the relative dose distribution of the original treatment plan. Results: For 30 of the 38 patients, dose escalation by individualized hypofractionation yielded therapeutic gain. For the maximally tolerable dose scheme in 33 fractions (MTD{sub 33}), individualized dose escalation resulted in a 2.5-21% gain in TTD. In the isotoxic schemes, the number of fractions could be reduced with a marginal increase in TED. For the maximally tolerable dose schemes, the TED could be escalated up to 36.6%, and for all patients beyond the level of the isotoxic and the MTD{sub 33} schemes (range, 3.3-36.6%). Reduction of the OTT contributed to the therapeutic gain of the shortened schemes. For the maximally tolerable schemes, the maximum esophageal dose was the dominant dose-limiting constraint in most patients. Conclusions: This modeling study showed that individualized dose prescription for hypofractionation in NSCLC radiotherapy, based on scaling of existing treatment plans up to normal tissue dose constraints, enables dose

  19. Interfractional Dose Variations in Intensity-Modulated Radiotherapy With Breath-Hold for Pancreatic Cancer

    SciTech Connect

    Nakamura, Mitsuhiro; Shibuya, Keiko; Nakamura, Akira; Shiinoki, Takehiro; Matsuo, Yukinori; Nakata, Manabu; Sawada, Akira; Mizowaki, Takashi; Hiraoka, Masahiro

    2012-04-01

    Purpose: To investigate the interfractional dose variations for intensity-modulated radiotherapy (RT) combined with breath-hold (BH) at end-exhalation (EE) for pancreatic cancer. Methods and Materials: A total of 10 consecutive patients with pancreatic cancer were enrolled. Each patient was fixed in the supine position on an individualized vacuum pillow with both arms raised. Computed tomography (CT) scans were performed before RT, and three additional scans were performed during the course of chemoradiotherapy using a conventional RT technique. The CT data were acquired under EE-BH conditions (BH-CT) using a visual feedback technique. The intensity-modulated RT plan, which used five 15-MV coplanar ports, was designed on the initial BH-CT set with a prescription dose of 39 Gy at 2.6 Gy/fraction. After rigid image registration between the initial and subsequent BH-CT scans, the dose distributions were recalculated on the subsequent BH-CT images under the same conditions as in planning. Changes in the dose-volume metrics of the gross tumor volume (GTV), clinical target volume (CTV = GTV + 5 mm), stomach, and duodenum were evaluated. Results: For the GTV and clinical target volume (CTV), the 95th percentile of the interfractional variations in the maximal dose, mean dose, dose covering 95% volume of the region of structure, and percentage of the volume covered by the 90% isodose line were within {+-}3%. Although the volume covered by the 39 Gy isodose line for the stomach and duodenum did not exceed 0.1 mL at planning, the volume covered by the 39 Gy isodose line for these structures was up to 11.4 cm{sup 3} and 1.8 cm{sup 3}, respectively. Conclusions: Despite variations in the gastrointestinal state and abdominal wall position at EE, the GTV and CTV were mostly ensured at the planned dose, with the exception of 1 patient. Compared with the duodenum, large variations in the stomach volume receiving high-dose radiation were observed, which might be beyond the

  20. Dose escalation in brachytherapy for cervical cancer: impact on (or increased need for) MRI-guided plan optimisation

    PubMed Central

    Paton, A M; Chalmers, K E; Coomber, H; Cameron, A L

    2012-01-01

    Objective The aim of this study was to assess the impact of dose escalation on the proportion of patients requiring MR image-guided optimisation rather than standard Manchester-based CT-guided planning, and the level of escalation achievable. Methods 30 patients with cervical cancer treated with external beam radiotherapy and image-guided brachytherapy (IGBT) had MR images acquired at the first fraction of IGBT. Gross tumour volume and high-risk clinical target volume (HR CTV) were contoured and treatment plans retrospectively produced for a range of total 2-Gy equivalent (EQD2) prescription doses from 66 Gyα/β=10 to 90 Gyα/β=10 (HR CTV D90). Standard Manchester system-style plans were produced, prescribed to point A and then optimised where necessary with the aim of delivering at least the prescription dose to the HR CTV D90 while respecting organ-at-risk (OAR) tolerances. Results Increasing the total EQD2 from 66 Gyα/β=10 to 90 Gyα/β=10 increased the number of plans requiring optimisation from 13.3% to 90%. After optimisation, the number of plans achieving the prescription dose ranged from 93.3% (66 Gyα/β=10) to 63.3% (90 Gyα/β=10) with the mean±standard deviation for HR CTV D90 EQD2 from 78.4±12.4 Gyα/β=10 (66 Gyα/β=10) to 94.1±19.9 Gyα/β=10 (90 Gyα/β=10). Conclusion As doses are escalated, the need for non-standard optimised planning increases, while benefits in terms of increased target doses actually achieved diminish. The maximum achievable target dose is ultimately limited by proximity of OARs. Advances in knowledge This work represents a guide for other centres in determining the highest practicable prescription doses while considering patient throughput and maintaining acceptable OAR doses. PMID:23175490

  1. Proton radiotherapy dose perturbations caused by esophageal stents of varying material composition are negligible in an experimental model

    PubMed Central

    Jalaj, Sujai; Lee, Sang Yeob; McGaw, Camille; John, Bijo K; Li, Zuofeng; Awad, Ziad T; Scolapio, James S; Munoz, Juan C

    2015-01-01

    Background: Self-expanding metal and plastic esophageal stents (SEMS and SEPS, respectively) are used in conjunction with chemoradiation for palliation of malignant dysphagia. To date, the dosimetric effects of stents undergoing proton radiotherapy are not known. Study aim: To investigate the proton radiotherapy dose perturbations caused by esophageal stents of varying designs and materials undergoing external beam treatment for esophageal cancer. Patients and methods: Simulated clinical protocol. Solid acrylic phantom was used to mimic the esophageal tissue environment. Stents made of nitinol, stainless steel and polyester were tested. Proton beam dose of 2 Gy-E was delivered to each stent in a single anterior to posterior field. Film and image based evidence of dose perturbation were main outcomes measured. Results: Only the stainless steel and plastic stents demonstrated slight overall dose attenuations (– 0.5 % and – 0.4 %, respectively). All the nitinol-based stents demonstrated minimal overall dose perturbations ranging from 0.0 % to 1.2 %. Negligible dose perturbations were observed on each of the stent surfaces proximal to the radiation source, ranging from – 0.8 % (stainless steel stent) to 1.0 % (nitinol stent). Negligible dose effects were also observed on the distal surfaces of each stent ranging from – 0.5 % (plastic and stainless steel stents) to 1.0 % (nitinol stent). Conclusion: Proton radiotherapy dose perturbations caused by stents of varying designs and material composition are negligible. Negligible dose perturbation is in keeping with the inherent advantage of proton therapy over traditional radiotherapy composed of photons – given its relative large mass, protons have little side scatter. PMID:26134771

  2. Imaging dose in breast radiotherapy: does breast size affect the dose to the organs at risk and the risk of secondary cancer to the contralateral breast?

    SciTech Connect

    Batumalai, Vikneswary; Quinn, Alexandra; Jameson, Michael; Delaney, Geoff; Holloway, Lois

    2015-03-15

    Correct target positioning is crucial for accurate dose delivery in breast radiotherapy resulting in utilisation of daily imaging. However, the radiation dose from daily imaging is associated with increased probability of secondary induced cancer. The aim of this study was to quantify doses associated with three imaging modalities and investigate the correlation of dose and varying breast size in breast radiotherapy. Planning computed tomography (CT) data sets of 30 breast cancer patients were utilised to simulate the dose received by various organs from a megavoltage computed tomography (MV-CT), megavoltage electronic portal image (MV-EPI) and megavoltage cone-beam computed tomography (MV-CBCT). The mean dose to organs adjacent to the target volume (contralateral breast, lungs, spinal cord and heart) were analysed. Pearson correlation analysis was performed to determine the relationship between imaging dose and primary breast volume and the lifetime attributable risk (LAR) of induced secondary cancer was calculated for the contralateral breast. The highest contralateral breast mean dose was from the MV-CBCT (1.79 Gy), followed by MV-EPI (0.22 Gy) and MV-CT (0.11 Gy). A similar trend was found for all organs at risk (OAR) analysed. The primary breast volume inversely correlated with the contralateral breast dose for all three imaging modalities. As the primary breast volume increases, the likelihood of a patient developing a radiation-induced secondary cancer to the contralateral breast decreases. MV-CBCT showed a stronger relationship between breast size and LAR of developing a radiation-induced contralateral breast cancer in comparison with the MV-CT and MV-EPI. For breast patients, imaging dose to OAR depends on imaging modality and treated breast size. When considering the use of imaging during breast radiotherapy, the patient's breast size and contralateral breast dose should be taken into account.

  3. Integral dose investigation of non-coplanar treatment beam geometries in radiotherapy

    SciTech Connect

    Nguyen, Dan; Dong, Peng; Ruan, Dan; Low, Daniel A.; Sheng, Ke; Long, Troy; Romeijn, Edwin

    2014-01-15

    Purpose: Automated planning and delivery of non-coplanar plans such as 4π radiotherapy involving a large number of fields have been developed to take advantage of the newly available automated couch and gantry on C-arm gantry linacs. However, there is an increasing concern regarding the potential changes in the integral dose that needs to be investigated. Methods: A digital torso phantom and 22 lung and liver stereotactic body radiation therapy (SBRT) patients were included in the study. The digital phantom was constructed as a water equivalent elliptical cylinder with a major axis length of 35.4 cm and minor axis of 23.6 cm. A 4.5 cm diameter target was positioned at varying depths along the major axis. Integral doses from intensity modulated, non-coplanar beams forming a conical pattern were compared against the equally spaced coplanar beam plans. Integral dose dependence on the phantom geometry and the beam number was also quantified. For the patient plans, the non-coplanar and coplanar beams and fluences were optimized using a column generation and pricing approach and compared against clinical VMAT plans using two full (lung) or partial coplanar arcs (liver) entering at the side proximal to the tumor. Both the average dose to the normal tissue volume and the total volumes receiving greater than 2 Gy (V2) and 5 Gy (V5) were evaluated and compared. Results: The ratio of integral dose from the non-coplanar and coplanar plans depended on the tumor depth for the phantom; for tumors shallower than 10 cm, the non-coplanar integral doses were lower than coplanar integral doses for non-coplanar angles less than 60°. Similar patterns were observed in the patient plans. The smallest non-coplanar integral doses were observed for tumor 6–8 cm deep. For the phantom, the integral dose was independent of the number of beams, consistent with the liver SBRT patients but the lung SBRT patients showed slight increase in the integral dose when more beams were used. Larger

  4. Reirradiation of Large-Volume Recurrent Glioma With Pulsed Reduced-Dose-Rate Radiotherapy

    SciTech Connect

    Adkison, Jarrod B.; Tome, Wolfgang; Seo, Songwon; Richards, Gregory M.; Robins, H. Ian; Rassmussen, Karl; Welsh, James S.; Mahler, Peter A.; Howard, Steven P.

    2011-03-01

    Purpose: Pulsed reduced-dose-rate radiotherapy (PRDR) is a reirradiation technique that reduces the effective dose rate and increases the treatment time, allowing sublethal damage repair during irradiation. Patients and Methods: A total of 103 patients with recurrent glioma underwent reirradiation using PRDR (86 considered to have Grade 4 at PRDR). PRDR was delivered using a series of 0.2-Gy pulses at 3-min intervals, creating an apparent dose rate of 0.0667 Gy/min to a median dose of 50 Gy (range, 20-60) delivered in 1.8-2.0-Gy fractions. The mean treatment volume was 403.5 {+-} 189.4 cm{sup 3} according to T{sub 2}-weighted magnetic resonance imaging and a 2-cm margin. Results: For the initial or upgraded Grade 4 cohort (n = 86), the median interval from the first irradiation to PRDR was 14 months. Patients undergoing PRDR within 14 months of the first irradiation (n = 43) had a median survival of 21 weeks. Those treated {>=}14 months after radiotherapy had a median survival of 28 weeks (n = 43; p = 0.004 and HR = 1.82 with a 95% CI ranging from 1.25 to 3.10). These data compared favorably to historical data sets, because only 16% of the patients were treated at first relapse (with 46% treated at the second relapse, 32% at the third or fourth relapse, and 4% at the fourth or fifth relapse). The median survival since diagnosis and retreatment was 6.3 years and 11.4 months for low-grade, 4.1 years and 5.6 months for Grade 3, and 1.6 years and 5.1 months for Grade 4 tumors, respectively, according to the initial histologic findings. Multivariate analysis revealed age at the initial diagnosis, initial low-grade disease, and Karnofsky performance score of {>=}80 to be significant predictors of survival after initiation of PRDR. Conclusion: PRDR allowed for safe retreatment of larger volumes to high doses with palliative benefit.

  5. Dose-volume delivery guided proton therapy using beam on-line PET system

    SciTech Connect

    Nishio, Teiji; Ogino, Takashi; Nomura, Kazuhiro; Uchida, Hiroshi

    2006-11-15

    Proton therapy is one form of radiotherapy in which the irradiation can be concentrated on a tumor using a scanned or modulated Bragg peak. Therefore, it is very important to evaluate the proton-irradiated volume accurately. The proton-irradiated volume can be confirmed by detection of pair annihilation gamma rays from positron emitter nuclei generated by the target nuclear fragment reaction of irradiated proton nuclei and nuclei in the irradiation target using a positron emission tomography (PET) apparatus, and dose-volume delivery guided proton therapy (DGPT) can thereby be achieved using PET images. In the proton treatment room, a beam ON-LINE PET system (BOLPs) was constructed so that a PET apparatus of the planar-type with a high spatial resolution of about 2 mm was mounted with the field of view covering the isocenter of the beam irradiation system. The position and intensity of activity were measured using the BOLPs immediately after the proton irradiation of a gelatinous water target containing {sup 16}O nuclei at different proton irradiation energy levels. The change of the activity-distribution range against the change of the physical range was observed within 2 mm. The experiments of proton irradiation to a rabbit and the imaging of the activity were performed. In addition, the proton beam energy used to irradiate the rabbit was changed. When the beam condition was changed, the difference between the two images acquired from the measurement of the BOLPs was confirmed to clearly identify the proton-irradiated volume.

  6. Comparison of Heart and Coronary Artery Doses Associated With Intensity-Modulated Radiotherapy Versus Three-Dimensional Conformal Radiotherapy for Distal Esophageal Cancer

    SciTech Connect

    Kole, Thomas P.; Aghayere, Osarhieme; Kwah, Jason; Yorke, Ellen D.; Goodman, Karyn A.

    2012-08-01

    Purpose: To compare heart and coronary artery radiation exposure using intensity-modulated radiotherapy (IMRT) vs. four-field three-dimensional conformal radiotherapy (3D-CRT) treatment plans for patients with distal esophageal cancer undergoing chemoradiation. Methods and Materials: Nineteen patients with distal esophageal cancers treated with IMRT from March 2007 to May 2008 were identified. All patients were treated to 50.4 Gy with five-field IMRT plans. Theoretical 3D-CRT plans with four-field beam arrangements were generated. Dose-volume histograms of the planning target volume, heart, right coronary artery, left coronary artery, and other critical normal tissues were compared between the IMRT and 3D-CRT plans, and selected parameters were statistically evaluated using the Wilcoxon rank-sum test. Results: Intensity-modulated radiotherapy treatment planning showed significant reduction (p < 0.05) in heart dose over 3D-CRT as assessed by average mean dose (22.9 vs. 28.2 Gy) and V30 (24.8% vs. 61.0%). There was also significant sparing of the right coronary artery (average mean dose, 23.8 Gy vs. 35.5 Gy), whereas the left coronary artery showed no significant improvement (mean dose, 11.2 Gy vs. 9.2 Gy), p = 0.11. There was no significant difference in percentage of total lung volume receiving at least 10, 15, or 20 Gy or in the mean lung dose between the planning methods. There were also no significant differences observed for the kidneys, liver, stomach, or spinal cord. Intensity-modulated radiotherapy achieved a significant improvement in target conformity as measured by the conformality index (ratio of total volume receiving 95% of prescription dose to planning target volume receiving 95% of prescription dose), with the mean conformality index reduced from 1.56 to 1.30 using IMRT. Conclusions: Treatment of patients with distal esophageal cancer using IMRT significantly decreases the exposure of the heart and right coronary artery when compared with 3D

  7. Reducing stray radiation dose to patients receiving passively scattered proton radiotherapy for prostate cancer

    PubMed Central

    Taddei, Phillip J; Fontenot, Jonas D; Zheng, Yuanshui; Mirkovic, Dragan; Lee, Andrew K; Titt, Uwe; Newhauser, Wayne D

    2014-01-01

    Proton beam radiotherapy exposes healthy tissue to stray radiation emanating from the treatment unit and secondary radiation produced within the patient. These exposures provide no known benefit and may increase a patient's risk of developing a radiogenic second cancer. The aim of this study was to explore strategies to reduce stray radiation dose to a patient receiving a 76 Gy proton beam treatment for cancer of the prostate. The whole-body effective dose from stray radiation, E, was estimated using detailed Monte Carlo simulations of a passively scattered proton treatment unit and an anthropomorphic phantom. The predicted value of E was 567 mSv, of which 320 mSv was attributed to leakage from the treatment unit; the remainder arose from scattered radiation that originated within the patient. Modest modifications of the treatment unit reduced E by 212 mSv. Surprisingly, E from a modified passive-scattering device was only slightly higher (109 mSv) than from a nozzle with no leakage, e.g., that which may be approached with a spot-scanning technique. These results add to the body of evidence supporting the suitability of passively scattered proton beams for the treatment of prostate cancer, confirm that the effective dose from stray radiation was not excessive, and, importantly, show that it can be substantially reduced by modest enhancements to the treatment unit. PMID:18369278

  8. Reducing stray radiation dose to patients receiving passively scattered proton radiotherapy for prostate cancer

    NASA Astrophysics Data System (ADS)

    Taddei, Phillip J.; Fontenot, Jonas D.; Zheng, Yuanshui; Mirkovic, Dragan; Lee, Andrew K.; Titt, Uwe; Newhauser, Wayne D.

    2008-04-01

    Proton beam radiotherapy exposes healthy tissue to stray radiation emanating from the treatment unit and secondary radiation produced within the patient. These exposures provide no known benefit and may increase a patient's risk of developing a radiogenic second cancer. The aim of this study was to explore strategies to reduce stray radiation dose to a patient receiving a 76 Gy proton beam treatment for cancer of the prostate. The whole-body effective dose from stray radiation, E, was estimated using detailed Monte Carlo simulations of a passively scattered proton treatment unit and an anthropomorphic phantom. The predicted value of E was 567 mSv, of which 320 mSv was attributed to leakage from the treatment unit; the remainder arose from scattered radiation that originated within the patient. Modest modifications of the treatment unit reduced E by 212 mSv. Surprisingly, E from a modified passive-scattering device was only slightly higher (109 mSv) than from a nozzle with no leakage, e.g., that which may be approached with a spot-scanning technique. These results add to the body of evidence supporting the suitability of passively scattered proton beams for the treatment of prostate cancer, confirm that the effective dose from stray radiation was not excessive, and, importantly, show that it can be substantially reduced by modest enhancements to the treatment unit.

  9. Impact of beam quality on megavoltage radiotherapy treatment techniques utilizing gold nanoparticles for dose enhancement

    NASA Astrophysics Data System (ADS)

    Tsiamas, Panagiotis; Liu, Bo; Cifter, Fulya; Ngwa, Wilfred F.; Berbeco, Ross I.; Kappas, Constantin; Theodorou, Kiriaki; Marcus, Karen; Makrigiorgos, Mike G.; Sajo, Erno; Zygmanski, Piotr

    2013-02-01

    This study determines the optimal clinical scenarios for gold nanoparticle dose enhancement as a function of irradiation conditions and potential biological targets using megavoltage x-ray beams. Four hundred and eighty clinical beams were studied for different potential cellular or sub-cellular targets. Beam quality was determined based on a 6 MV linac with and without a flattening filter for various delivery conditions. Dose enhancement ratios DER = DGNP/Dwater were calculated for all cases using the GEANT4 Monte Carlo code and the CEPXS/ONEDANT radiation transport deterministic code. Dose enhancement using GEANT4 agreed with CEPXS/ONEDANT. DER for unflattened beams is ∼2 times larger than for flattened beams. The maximum DER values were calculated for split-IMRT fields (∼6) and for out-of-field areas of an unflattened linac (∼17). In-field DER values, at the surface of gold nanoparticles, ranged from 2.2 to 4.2 (flattened beam) and from 3 to 4.7 (unflattened beams). For a GNP cluster with thicknesses of 10 and 100 nm, the DER ranges from 14% to 287%. DER is the greatest for split-IMRT, larger depths, out-of-field areas and/or unflattened linac. Mapping of a GNP location in tumor and normal tissue is essential for efficient and safe delivery of nanoparticle-enhanced radiotherapy.

  10. A motorized solid-state phantom for patient-specific dose verification in ion beam radiotherapy

    NASA Astrophysics Data System (ADS)

    Henkner, K.; Winter, M.; Echner, G.; Ackermann, B.; Brons, S.; Horn, J.; Jäkel, O.; Karger, C. P.

    2015-09-01

    For regular quality assurance and patient-specific dosimetric verification under non-horizontal gantry angles in ion beam radiotherapy, we developed and commissioned a motorized solid state phantom. The phantom is set up under the selected gantry angle and moves an array of 24 ionization chambers to the measurement position by means of three eccentrically-mounted cylinders. Hence, the phantom allows 3D dosimetry at oblique gantry angles. To achieve the high standards in dosimetry, the mechanical and dosimetric accuracy of the phantom was investigated and corrections for residual uncertainties were derived. Furthermore, the exact geometry as well as a coordinate transformation from cylindrical into Cartesian coordinates was determined. The developed phantom proved to be suitable for quality assurance and 3D-dose verifications for proton- and carbon ion treatment plans at oblique gantry angles. Comparing dose measurements with the new phantom under oblique gantry angles with those in a water phantom and horizontal beams, the dose deviations averaged over the 24 ionization chambers were within 1.5%. Integrating the phantom into the HIT treatment plan verification environment, allows the use of established workflow for verification measurements. Application of the phantom increases the safety of patient plan application at gantry beam lines.

  11. Role of Intensity-Modulated Radiotherapy in Reducing Toxicity in Dose Escalation for Localized Prostate Cancer

    SciTech Connect

    Al-Mamgani, Abrahim Heemsbergen, Wilma D.; Peeters, Stephanie T.H.; Lebesque, Joos V.

    2009-03-01

    Purpose: To compare the acute and late gastrointestinal (GI) and genitourinary (GU) toxicity in prostate cancer patients treated to a total dose of 78 Gy with either a three-conformal radiotherapy technique with a sequential boost (SEQ) or a simultaneous integrated boost using intensity-modulated radiotherapy (SIB-IMRT). Patients and Methods: A total of 78 prostate cancer patients participating in the randomized Dutch trial comparing 68 Gy and 78 Gy were the subject of this analysis. They were all treated at the same institution to a total dose of 78 Gy. The median follow-up was 76 and 56 months for the SEQ and SIB-IMRT groups, respectively. The primary endpoints were acute and late GI and GU toxicity. Results: A significantly lower incidence of acute Grade 2 or greater GI toxicity occurred in patients treated with SIB-IMRT compared with SEQ (20% vs. 61%, p = 0.001). For acute GU toxicity and late GI and GU toxicity, the incidence was lower after SIB-IMRT, but these differences were not statistically significant. No statistically significant difference were found in the 5-year freedom from biochemical failure rate (Phoenix definition) between the two groups (70% for the SIB-IMRT group vs. 61% for the SEQ group, p = 0.3). The same was true for the 5-year freedom from clinical failure rate (90% vs. 72%, p = 0.07). Conclusion: The results of our study have shown that SIB-IMRT reduced the toxicity without compromising the outcome in patients with localized prostate cancer treated to 78 Gy radiation.

  12. Reliability of the Bony Anatomy in Image-Guided Stereotactic Radiotherapy of Brain Metastases

    SciTech Connect

    Guckenberger, Matthias Baier, Kurt; Guenther, Iris; Richter, Anne; Wilbert, Juergen; Sauer, Otto; Vordermark, Dirk; Flentje, Michael

    2007-09-01

    Purpose: To evaluate whether the position of brain metastases remains stable between planning and treatment in cranial stereotactic radiotherapy (SRT). Methods and Materials: Eighteen patients with 20 brain metastases were treated with single-fraction (17 lesions) or hypofractionated (3 lesions) image-guided SRT. Median time interval between planning and treatment was 8 days. Before treatment a cone-beam CT (CBCT) and a conventional CT after application of i.v. contrast were acquired. Setup errors using automatic bone registration (CBCT) and manual soft-tissue registration of the brain metastases (conventional CT) were compared. Results: Tumor size was not significantly different between planning and treatment. The three-dimensional setup error (mean {+-} SD) was 4.0 {+-} 2.1 mm and 3.5 {+-} 2.2 mm according to the bony anatomy and the lesion itself, respectively. A highly significant correlation between automatic bone match and soft-tissue registration was seen in all three directions (r {>=} 0.88). The three-dimensional distance between the isocenter according to bone match and soft-tissue registration was 1.7 {+-} 0.7 mm, maximum 2.8 mm. Treatment of intracranial pressure with steroids did not influence the position of the lesion relative to the bony anatomy. Conclusion: With a time interval of approximately 1 week between planning and treatment, the bony anatomy of the skull proved to be an excellent surrogate for the target position in image-guided SRT.

  13. Intensity-Modulated Radiotherapy for Locally Advanced Non-Small-Cell Lung Cancer: A Dose-Escalation Planning Study

    SciTech Connect

    Lievens, Yolande; Nulens, An; Gaber, Mousa Amr; Defraene, Gilles; De Wever, Walter; Stroobants, Sigrid; Van den Heuvel, Frank

    2011-05-01

    Purpose: To evaluate the potential for dose escalation with intensity-modulated radiotherapy (IMRT) in positron emission tomography-based radiotherapy planning for locally advanced non-small-cell lung cancer (LA-NSCLC). Methods and Materials: For 35 LA-NSCLC patients, three-dimensional conformal radiotherapy and IMRT plans were made to a prescription dose (PD) of 66 Gy in 2-Gy fractions. Dose escalation was performed toward the maximal PD using secondary endpoint constraints for the lung, spinal cord, and heart, with de-escalation according to defined esophageal tolerance. Dose calculation was performed using the Eclipse pencil beam algorithm, and all plans were recalculated using a collapsed cone algorithm. The normal tissue complication probabilities were calculated for the lung (Grade 2 pneumonitis) and esophagus (acute toxicity, grade 2 or greater, and late toxicity). Results: IMRT resulted in statistically significant decreases in the mean lung (p <.0001) and maximal spinal cord (p = .002 and 0005) doses, allowing an average increase in the PD of 8.6-14.2 Gy (p {<=}.0001). This advantage was lost after de-escalation within the defined esophageal dose limits. The lung normal tissue complication probabilities were significantly lower for IMRT (p <.0001), even after dose escalation. For esophageal toxicity, IMRT significantly decreased the acute NTCP values at the low dose levels (p = .0009 and p <.0001). After maximal dose escalation, late esophageal tolerance became critical (p <.0001), especially when using IMRT, owing to the parallel increases in the esophageal dose and PD. Conclusion: In LA-NSCLC, IMRT offers the potential to significantly escalate the PD, dependent on the lung and spinal cord tolerance. However, parallel increases in the esophageal dose abolished the advantage, even when using collapsed cone algorithms. This is important to consider in the context of concomitant chemoradiotherapy schedules using IMRT.

  14. Statistical Determination of the Gating Windows for Respiratory-Gated Radiotherapy Using a Visible Guiding System.

    PubMed

    Oh, Se An; Yea, Ji Woon; Kim, Sung Kyu

    2016-01-01

    Respiratory-gated radiation therapy (RGRT) is used to minimize the radiation dose to normal tissue in lung-cancer patients. Although determining the gating window in the respiratory phase of patients is important in RGRT, it is not easy. Our aim was to determine the optimal gating window when using a visible guiding system for RGRT. Between April and October 2014, the breathing signals of 23 lung-cancer patients were recorded with a real-time position management (RPM) respiratory gating system (Varian, USA). We performed statistical analysis with breathing signals to find the optimal gating window for guided breathing in RGRT. When we compared breathing signals before and after the breathing training, 19 of the 23 patients showed statistically significant differences (p < 0.05). The standard deviation of the respiration signals after breathing training was lowest for phases of 30%-70%. The results showed that the optimal gating window in RGRT is 40% (30%-70%) with respect to repeatability for breathing after respiration training with the visible guiding system. RGRT was performed with the RPM system to confirm the usefulness of the visible guiding system. The RPM system and our visible guiding system improve the respiratory regularity, which in turn should improve the accuracy and efficiency of RGRT. PMID:27228097

  15. Statistical Determination of the Gating Windows for Respiratory-Gated Radiotherapy Using a Visible Guiding System

    PubMed Central

    Oh, Se An; Yea, Ji Woon

    2016-01-01

    Respiratory-gated radiation therapy (RGRT) is used to minimize the radiation dose to normal tissue in lung-cancer patients. Although determining the gating window in the respiratory phase of patients is important in RGRT, it is not easy. Our aim was to determine the optimal gating window when using a visible guiding system for RGRT. Between April and October 2014, the breathing signals of 23 lung-cancer patients were recorded with a real-time position management (RPM) respiratory gating system (Varian, USA). We performed statistical analysis with breathing signals to find the optimal gating window for guided breathing in RGRT. When we compared breathing signals before and after the breathing training, 19 of the 23 patients showed statistically significant differences (p < 0.05). The standard deviation of the respiration signals after breathing training was lowest for phases of 30%–70%. The results showed that the optimal gating window in RGRT is 40% (30%–70%) with respect to repeatability for breathing after respiration training with the visible guiding system. RGRT was performed with the RPM system to confirm the usefulness of the visible guiding system. The RPM system and our visible guiding system improve the respiratory regularity, which in turn should improve the accuracy and efficiency of RGRT. PMID:27228097

  16. Evaluation of Gafchromic EBT-XD film, with comparison to EBT3 film, and application in high dose radiotherapy verification.

    PubMed

    Palmer, Antony L; Dimitriadis, Alexis; Nisbet, Andrew; Clark, Catharine H

    2015-11-21

    There is renewed interest in film dosimetry for the verification of dose delivery of complex treatments, particularly small fields, compared to treatment planning system calculations. A new radiochromic film, Gafchromic EBT-XD, is available for high-dose treatment verification and we present the first published evaluation of its use. We evaluate the new film for MV photon dosimetry, including calibration curves, performance with single- and triple-channel dosimetry, and comparison to existing EBT3 film. In the verification of a typical 25 Gy stereotactic radiotherapy (SRS) treatment, compared to TPS planned dose distribution, excellent agreement was seen with EBT-XD using triple-channel dosimetry, in isodose overlay, maximum 1.0 mm difference over 200-2400 cGy, and gamma evaluation, mean passing rate 97% at 3% locally-normalised, 1.5 mm criteria. In comparison to EBT3, EBT-XD gave improved evaluation results for the SRS-plan, had improved calibration curve gradients at high doses, and had reduced lateral scanner effect. The dimensions of the two films are identical. The optical density of EBT-XD is lower than EBT3 for the same dose. The effective atomic number for both may be considered water-equivalent in MV radiotherapy. We have validated the use of EBT-XD for high-dose, small-field radiotherapy, for routine QC and a forthcoming multi-centre SRS dosimetry intercomparison. PMID:26512917

  17. Evaluation of Gafchromic EBT-XD film, with comparison to EBT3 film, and application in high dose radiotherapy verification

    NASA Astrophysics Data System (ADS)

    Palmer, Antony L.; Dimitriadis, Alexis; Nisbet, Andrew; Clark, Catharine H.

    2015-11-01

    There is renewed interest in film dosimetry for the verification of dose delivery of complex treatments, particularly small fields, compared to treatment planning system calculations. A new radiochromic film, Gafchromic EBT-XD, is available for high-dose treatment verification and we present the first published evaluation of its use. We evaluate the new film for MV photon dosimetry, including calibration curves, performance with single- and triple-channel dosimetry, and comparison to existing EBT3 film. In the verification of a typical 25 Gy stereotactic radiotherapy (SRS) treatment, compared to TPS planned dose distribution, excellent agreement was seen with EBT-XD using triple-channel dosimetry, in isodose overlay, maximum 1.0 mm difference over 200-2400 cGy, and gamma evaluation, mean passing rate 97% at 3% locally-normalised, 1.5 mm criteria. In comparison to EBT3, EBT-XD gave improved evaluation results for the SRS-plan, had improved calibration curve gradients at high doses, and had reduced lateral scanner effect. The dimensions of the two films are identical. The optical density of EBT-XD is lower than EBT3 for the same dose. The effective atomic number for both may be considered water-equivalent in MV radiotherapy. We have validated the use of EBT-XD for high-dose, small-field radiotherapy, for routine QC and a forthcoming multi-centre SRS dosimetry intercomparison.

  18. SU-E-T-500: Dose Escalation Strategy for Lung Cancer Patients Using a Biologically- Guided Target Definition

    SciTech Connect

    Shusharina, N; Khan, F; Choi, N; Sharp, G

    2014-06-01

    Purpose: Dose escalation strategy for lung cancer patients can lead to late symptoms such as pneumonitis and cardiac injury. We propose a strategy to increase radiation dose for improving local tumor control while simultaneously striving to minimize the injury of organs at risk (OAR). Our strategy is based on defining a small, biologically-guided target volume for receiving additional radiation dose. Methods: 106 patients with lung cancer treated with radiotherapy were selected for patients diagnosed with stage II and III disease. Previous research has shown that 50% of the maximum SUV threshold in FDG-PET imaging is appropriate for delineation of the most aggressive part of a tumor. After PET- and CT-derived targets were contoured, an IMRT treatment plan was designed to deliver 60 Gy to the GTV as delineated on a 4D CT (Plan 1). A second plan was designed with additional dose of 18 Gy to the PET-derived volume (Plan 2). A composite plan was generated by the addition of Plan 1 and Plan 2. Results: Plan 1 was compared to the composite plan and increases in OAR dose were assessed. For seven patients on average, lung V5 was increased by 1.4% and V20 by 4.2% for ipsilateral lung and by 13.5% and 7% for contralateral lung. For total lung, V5 and V20 were increased by 4.5% and 4.8% respectively. Mean lung dose was increased by 9.7% for the total lung. The maximum dose to the spinal cord increased by 16% on average. For the heart, V20 increased by 4.2% and V40 by 5.2%. Conclusion: It seems feasible that an additional 18 Gy of radiation dose can be delivered to FDG PET-derived subvolume of the CT-based GTV of the primary tumor without significant increase in total dose to the critical organs such as lungs, spinal cord and heart.

  19. Patient Selection and Activity Planning Guide for Selective Internal Radiotherapy With Yttrium-90 Resin Microspheres

    SciTech Connect

    Lau, Wan-Yee; Kennedy, Andrew S.; Kim, Yun Hwan; Lai, Hee Kit; Lee, Rheun-Chuan; Leung, Thomas W.T.; Liu, Ching-Sheng; Salem, Riad; Sangro, Bruno; Shuter, Borys; Wang, Shih-Chang

    2012-01-01

    Purpose: Selective internal radiotherapy (SIRT) with yttrium-90 ({sup 90}Y) resin microspheres can improve the clinical outcomes for selected patients with inoperable liver cancer. This technique involves intra-arterial delivery of {beta}-emitting microspheres into hepatocellular carcinomas or liver metastases while sparing uninvolved structures. Its unique mode of action, including both {sup 90}Y brachytherapy and embolization of neoplastic microvasculature, necessitates activity planning methods specific to SIRT. Methods and Materials: A panel of clinicians experienced in {sup 90}Y resin microsphere SIRT was convened to integrate clinical experience with the published data to propose an activity planning pathway for radioembolization. Results: Accurate planning is essential to minimize potentially fatal sequelae such as radiation-induced liver disease while delivering tumoricidal {sup 90}Y activity. Planning methods have included empiric dosing according to degree of tumor involvement, empiric dosing adjusted for the body surface area, and partition model calculations using Medical Internal Radiation Dose principles. It has been recommended that at least two of these methods be compared when calculating the microsphere activity for each patient. Conclusions: Many factors inform {sup 90}Y resin microsphere SIRT activity planning, including the therapeutic intent, tissue and vasculature imaging, tumor and uninvolved liver characteristics, previous therapies, and localization of the microsphere infusion. The influence of each of these factors has been discussed.

  20. Measurement of radiotherapy x-ray skin dose on a chest wall phantom.

    PubMed

    Quach, K Y; Morales, J; Butson, M J; Rosenfeld, A B; Metcalfe, P E

    2000-07-01

    Sufficient skin dose needs to be delivered by a radiotherapy chest wall treatment regimen to ensure the probability of a near surface tumor recurrence is minimized. To simulate a chest wall treatment a hemicylindrical solid water phantom of 7.5 cm radius was irradiated with 6 MV x-rays using 20x20 cm2 and 10x20 cm2 fields at 100 cm source surface distance (SSD) to the base of the phantom. A surface dose profile was obtained from 0 to 180 degrees, in 10 degrees increments around the circumference of the phantom. Dosimetry results obtained from radiochromic film (effective depth of 0.17 mm) were used in the investigation, the superficial doses were found to be 28% (of Dmax) at the 0 degrees beam entry position and 58% at the 90 degrees oblique beam position. Superficial dose results were also obtained using extra thin thermoluminescent dosimeters (TLD) (effective depth 0.14 mm) of 30% at 0 degrees, 57% at 90 degrees, and a metal oxide semiconductor field effect transistor (MOSFET) detector (effective depth 0.5 mm) of 43% at 0 degrees, 62% at 90 degrees. Because the differences in measured superficial doses were significant and beyond those related to experimental error, these differences are assumed to be mostly attributable to the effective depth of measurement of each detector. We numerically simulated a bolus on/bolus off technique and found we could increase the coverage to the skin. Using an alternate "bolus on," "bolus off" regimen, the skin would receive 36.8 Gy at 0 degrees incidence and 46.4 Gy at 90 degrees incidence for a prescribed midpoint dose of 50 Gy. From this work it is evident that, as the circumference of the phantom is traversed the SSD increases and hence there is an inverse square fluence fall-off, this is more than offset by the increase in skin dose due to surface curvature to a plateau at about 90 degrees. Beyond this angle it is assumed that beam attenuation through the phantom and inverse square fall-off is causing the surface dose to

  1. Characterization of a novel EPID designed for simultaneous imaging and dose verification in radiotherapy

    SciTech Connect

    Blake, Samuel J.; McNamara, Aimee L.; Deshpande, Shrikant; Holloway, Lois; Greer, Peter B.; Kuncic, Zdenka; Vial, Philip

    2013-09-15

    Purpose: Standard amorphous silicon electronic portal imaging devices (a-Si EPIDs) are x-ray imagers used frequently in radiotherapy that indirectly detect incident x-rays using a metal plate and phosphor screen. These detectors may also be used as two-dimensional dosimeters; however, they have a well-characterized nonwater-equivalent dosimetric response. Plastic scintillating (PS) fibers, on the other hand, have been shown to respond in a water-equivalent manner to x-rays in the energy range typically encountered during radiotherapy. In this study, the authors report on the first experimental measurements taken with a novel prototype PS a-Si EPID developed for the purpose of performing simultaneous imaging and dosimetry in radiotherapy. This prototype employs an array of PS fibers in place of the standard metal plate and phosphor screen. The imaging performance and dosimetric response of the prototype EPID were evaluated experimentally and compared to that of the standard EPID.Methods: Clinical 6 MV photon beams were used to first measure the detector sensitivity, linearity of dose response, and pixel noise characteristics of the prototype and standard EPIDs. Second, the dosimetric response of each EPID was evaluated relative to a reference water-equivalent dosimeter by measuring the off-axis and field size response in a nontransit configuration, along with the off-axis, field size, and transmission response in a transit configuration using solid water blocks. Finally, the imaging performance of the prototype and standard EPIDs was evaluated quantitatively by using an image quality phantom to measure the contrast to noise ratio (CNR) and spatial resolution of images acquired with each detector, and qualitatively by using an anthropomorphic phantom to acquire images representative of human anatomy.Results: The prototype EPID's sensitivity was 0.37 times that of the standard EPID. Both EPIDs exhibited responses that were linear with delivered dose over a range of 1

  2. Cancer risk estimates from the combined Japanese A-bomb and Hodgkin cohorts for doses relevant to radiotherapy.

    PubMed

    Schneider, Uwe; Walsh, Linda

    2008-04-01

    Most information on the dose-response of radiation-induced cancer is derived from data on the A-bomb survivors who were exposed to gamma-rays and neutrons. Since, for radiation protection purposes, the dose span of main interest is between 0 and 1 Gy, the analysis of the A-bomb survivors is usually focused on this range. However, estimates of cancer risk for doses above 1 Gy are becoming more important for radiotherapy patients and for long-term manned missions in space research. Therefore in this work, emphasis is placed on doses relevant for radiotherapy with respect to radiation-induced solid cancer. The analysis of the A-bomb survivor's data was extended by including two extra high-dose categories (4-6 Sv and 6-13 Sv) and by an attempted combination with cancer data on patients receiving radiotherapy for Hodgkin's disease. In addition, since there are some recent indications for a high neutron dose contribution, the data were fitted separately for three different values for the relative biological effectiveness (RBE) of the neutrons (10, 35 and 100) and a variable RBE as a function of dose. The data were fitted using a linear, a linear-exponential and a plateau-dose-response relationship. Best agreement was found for the plateau model with a dose-varying RBE. It can be concluded that for doses above 1 Gy there is a tendency for a nonlinear dose-response curve. In addition, there is evidence of a neutron RBE greater than 10 for the A-bomb survivor data. Many problems and uncertainties are involved in combing these two datasets. However, since very little is currently known about the shape of dose-response relationships for radiation-induced cancer in the radiotherapy dose range, this approach could be regarded as a first attempt to acquire more information on this area. The work presented here also provides the first direct evidence that the bending over of the solid cancer excess risk dose response curve for the A-bomb survivors, generally observed above 2 Gy

  3. Feasibility of a Multigroup Deterministic Solution Method for 3D Radiotherapy Dose Calculations

    PubMed Central

    Vassiliev, Oleg N.; Wareing, Todd A.; Davis, Ian M.; McGhee, John; Barnett, Douglas; Horton, John L.; Gifford, Kent; Failla, Gregory; Titt, Uwe; Mourtada, Firas

    2008-01-01

    Purpose To investigate the potential of a novel deterministic solver, Attila, for external photon beam radiotherapy dose calculations. Methods and Materials Two hypothetical cases for prostate and head and neck cancer photon beam treatment plans were calculated using Attila and EGSnrc Monte Carlo simulations. Open beams were modeled as isotropic photon point sources collimated to specified field sizes (100 cm SSD). The sources had a realistic energy spectrum calculated by Monte Carlo for a Varian Clinac 2100 operated in a 6MV photon mode. The Attila computational grids consisted of 106,000 elements, or 424,000 spatial degrees of freedom, for the prostate case, and 123,000 tetrahedral elements, or 492,000 spatial degrees of freedom, for the head and neck cases. Results For both cases, results demonstrate excellent agreement between Attila and EGSnrc in all areas, including the build-up regions, near heterogeneities, and at the beam penumbra. Dose agreement for 99% of the voxels was within 3% (relative point-wise difference) or 3mm distance-to-agreement criterion. Localized differences between the Attila and EGSnrc results were observed at bone and soft tissue interfaces, and are attributable to the effect of voxel material homogenization in calculating dose-to-medium in EGSnrc. For both cases, Attila calculation times were under 20 CPU minutes on a single 2.2 GHz AMD Opteron processor. Conclusions The methods in Attila have the potential to be the basis for an efficient dose engine for patient specific treatment planning, providing accuracy similar to that obtained by Monte Carlo. PMID:18722273

  4. Feasibility of a Multigroup Deterministic Solution Method for Three-Dimensional Radiotherapy Dose Calculations

    SciTech Connect

    Vassiliev, Oleg N.; Wareing, Todd A.; Davis, Ian M; McGhee, John; Barnett, Douglas; Horton, John L.; Gifford, Kent; Failla, Gregory; Titt, Uwe; Mourtada, Firas

    2008-09-01

    Purpose: To investigate the potential of a novel deterministic solver, Attila, for external photon beam radiotherapy dose calculations. Methods and Materials: Two hypothetical cases for prostate and head-and-neck cancer photon beam treatment plans were calculated using Attila and EGSnrc Monte Carlo simulations. Open beams were modeled as isotropic photon point sources collimated to specified field sizes. The sources had a realistic energy spectrum calculated by Monte Carlo for a Varian Clinac 2100 operated in a 6-MV photon mode. The Attila computational grids consisted of 106,000 elements, or 424,000 spatial degrees of freedom, for the prostate case, and 123,000 tetrahedral elements, or 492,000 spatial degrees of freedom, for the head-and-neck cases. Results: For both cases, results demonstrate excellent agreement between Attila and EGSnrc in all areas, including the build-up regions, near heterogeneities, and at the beam penumbra. Dose agreement for 99% of the voxels was within the 3% (relative point-wise difference) or 3-mm distance-to-agreement criterion. Localized differences between the Attila and EGSnrc results were observed at bone and soft-tissue interfaces and are attributable to the effect of voxel material homogenization in calculating dose-to-medium in EGSnrc. For both cases, Attila calculation times were <20 central processing unit minutes on a single 2.2-GHz AMD Opteron processor. Conclusions: The methods in Attila have the potential to be the basis for an efficient dose engine for patient-specific treatment planning, providing accuracy similar to that obtained by Monte Carlo.

  5. Evaluating Proton Stereotactic Body Radiotherapy to Reduce Chest Wall Dose in the Treatment of Lung Cancer

    PubMed Central

    Welsh, James; Nguyen, Ngoc; Palmer, Matt; Allen, Pamela K.; Paolini, Michael; Liao, Zhongxing; Bluett, Jaques; Mohan, Radhe; Gomez, Daniel; Cox, James D.; Komaki, Ritsuko; Chang, Joe Y.

    2014-01-01

    Purpose Stereotactic body radiotherapy (SBRT) can produce excellent local control of several types of solid tumor; however, toxicity to nearby critical structures is a concern. We found previously that in SBRT for lung cancer, the chest wall (CW) volume receiving 20, 30, or 40 Gy (V20, V30, or V40) was linked with the development of neuropathy. Here we sought to determine whether the dosimetric advantages of protons could produce lower CW doses than traditional photon-based SBRT. Methods We searched an institutional database to identify patients treated with photon SBRT for lung cancer with tumors within <2.5 cm of the CW. We found 260 cases; of these chronic grade ≥2 CW pain was identified in 23 patients. We then selected 10 representative patients from this group and generated proton SBRT treatment plans, using the identical dose of 50 Gy in 4 fractions, and assessed potential differences in CW dose between the two plans. Results The proton SBRT plans reduced the CW doses at all dose levels measured. The median CW V was 364.0 cm320 for photons and 160.0 cm3 for protons (P<0.0001); V30 was 144.6 cm3 for photons vs. 77.0 cm3 for protons (P=0.0012); V was 93.9 cm335 for photons vs. 57.9 cm3 for protons (P=0.005); V40 was 66.5 cm3 for photons vs. 45.4 cm3 for protons (P=0.0112); and mean lung dose was 5.9 Gy for photons vs. 3.8 Gy for protons (P=0.0001). Coverage of the planning target volume was comparable between the two sets of plans (96.4% for photons and 97% for protons). Conclusions From a dosimetric standpoint, proton SBRT can achieve the same coverage of the PTV while significantly reducing the dose to the CW and lung relative to photon SBRT and therefore may be beneficial for the treatment of lesions close to critical structures. PMID:24200220

  6. Evaluating proton stereotactic body radiotherapy to reduce chest wall dose in the treatment of lung cancer

    SciTech Connect

    Welsh, James; Amini, Arya; Ciura, Katherine; Nguyen, Ngoc; Palmer, Matt; Soh, Hendrick; Allen, Pamela K.; Paolini, Michael; Liao, Zhongxing; Bluett, Jaques; Mohan, Radhe; Gomez, Daniel; Cox, James D.; Komaki, Ritsuko; Chang, Joe Y.

    2013-01-01

    Stereotactic body radiotherapy (SBRT) can produce excellent local control of several types of solid tumor; however, toxicity to nearby critical structures is a concern. We found previously that in SBRT for lung cancer, the chest wall (CW) volume receiving 20, 30, or 40 Gy (V{sub 20}, V{sub 30}, or V{sub 40}) was linked with the development of neuropathy. Here we sought to determine whether the dosimetric advantages of protons could produce lower CW doses than traditional photon-based SBRT. We searched an institutional database to identify patients treated with photon SBRT for lung cancer with tumors within < 2.5 cm of the CW. We found 260 cases; of these, chronic grade ≥ 2 CW pain was identified in 23 patients. We then selected 10 representative patients from this group and generated proton SBRT treatment plans, using the identical dose of 50 Gy in 4 fractions, and assessed potential differences in CW dose between the 2 plans. The proton SBRT plans reduced the CW doses at all dose levels measured. The median CW V{sub 20} was 364.0 cm{sup 3} and 160.0 cm{sup 3} (p < 0.0001), V{sub 30} was 144.6 cm{sup 3}vs 77.0 cm{sup 3} (p = 0.0012), V{sub 35} was 93.9 cm{sup 3}vs 57.9 cm{sup 3} (p = 0.005), V{sub 40} was 66.5 cm{sup 3}vs 45.4 cm{sup 3} (p = 0.0112), and mean lung dose was 5.9 Gy vs 3.8 Gy (p = 0.0001) for photons and protons, respectively. Coverage of the planning target volume (PTV) was comparable between the 2 sets of plans (96.4% for photons and 97% for protons). From a dosimetric standpoint, proton SBRT can achieve the same coverage of the PTV while significantly reducing the dose to the CW and lung relative to photon SBRT and therefore may be beneficial for the treatment of lesions closer to critical structures.

  7. Recommendations for dose calculations of lung cancer treatment plans treated with stereotactic ablative body radiotherapy (SABR)

    NASA Astrophysics Data System (ADS)

    Devpura, S.; Siddiqui, M. S.; Chen, D.; Liu, D.; Li, H.; Kumar, S.; Gordon, J.; Ajlouni, M.; Movsas, B.; Chetty, I. J.

    2014-03-01

    The purpose of this study was to systematically evaluate dose distributions computed with 5 different dose algorithms for patients with lung cancers treated using stereotactic ablative body radiotherapy (SABR). Treatment plans for 133 lung cancer patients, initially computed with a 1D-pencil beam (equivalent-path-length, EPL-1D) algorithm, were recalculated with 4 other algorithms commissioned for treatment planning, including 3-D pencil-beam (EPL-3D), anisotropic analytical algorithm (AAA), collapsed cone convolution superposition (CCC), and Monte Carlo (MC). The plan prescription dose was 48 Gy in 4 fractions normalized to the 95% isodose line. Tumors were classified according to location: peripheral tumors surrounded by lung (lung-island, N=39), peripheral tumors attached to the rib-cage or chest wall (lung-wall, N=44), and centrally-located tumors (lung-central, N=50). Relative to the EPL-1D algorithm, PTV D95 and mean dose values computed with the other 4 algorithms were lowest for "lung-island" tumors with smallest field sizes (3-5 cm). On the other hand, the smallest differences were noted for lung-central tumors treated with largest field widths (7-10 cm). Amongst all locations, dose distribution differences were most strongly correlated with tumor size for lung-island tumors. For most cases, convolution/superposition and MC algorithms were in good agreement. Mean lung dose (MLD) values computed with the EPL-1D algorithm were highly correlated with that of the other algorithms (correlation coefficient =0.99). The MLD values were found to be ~10% lower for small lung-island tumors with the model-based (conv/superposition and MC) vs. the correction-based (pencil-beam) algorithms with the model-based algorithms predicting greater low dose spread within the lungs. This study suggests that pencil beam algorithms should be avoided for lung SABR planning. For the most challenging cases, small tumors surrounded entirely by lung tissue (lung-island type), a Monte

  8. Biological Image-Guided Radiotherapy in Rectal Cancer: Challenges and Pitfalls

    SciTech Connect

    Roels, Sarah; Slagmolen, Pieter; Lee, John A.; Loeckx, Dirk; Maes, Frederik; Stroobants, Sigrid; Ectors, Nadine; Penninckx, Freddy; Haustermans, Karin

    2009-11-01

    Purpose: To investigate the feasibility of integrating multiple imaging modalities for image-guided radiotherapy in rectal cancer. Patients and Methods: Magnetic resonance imaging (MRI) and fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) were performed before, during, and after preoperative chemoradiotherapy (CRT) in patients with resectable rectal cancer. The FDG-PET signals were segmented with an adaptive threshold-based and a gradient-based method. Magnetic resonance tumor volumes (TVs) were manually delineated. A nonrigid registration algorithm was applied to register the images, and mismatch analyses were carried out between MR and FDG-PET TVs and between TVs over time. Tumor volumes delineated on the images after CRT were compared with the pathologic TV. Results: Forty-five FDG-PET/CT and 45 MR images were analyzed from 15 patients. The mean MRI and FDG-PET TVs showed a tendency to shrink during and after CRT. In general, MRI showed larger TVs than FDG-PET. There was an approximately 50% mismatch between the FDG-PET TV and the MRI TV at baseline and during CRT. Sixty-one percent of the FDG-PET TV and 76% of the MRI TV obtained after 10 fractions of CRT remained inside the corresponding baseline TV. On MRI, residual tumor was still suspected in all 6 patients with a pathologic complete response, whereas FDG-PET showed a metabolic complete response in 3 of them. The FDG-PET TVs delineated with the gradient-based method matched closest with pathologic findings. Conclusions: Integration of MRI and FDG-PET into radiotherapy seems feasible. Gradient-based segmentation is recommended for FDG-PET. Spatial variance between MRI and FDG-PET TVs should be taken into account for target definition.

  9. Magnetization curves of sintered heavy tungsten alloys for applications in MRI-guided radiotherapy

    SciTech Connect

    Kolling, Stefan; Oborn, Bradley M.; Keall, Paul J.; Horvat, Joseph

    2014-06-15

    Purpose: Due to the current interest in MRI-guided radiotherapy, the magnetic properties of the materials commonly used in radiotherapy are becoming increasingly important. In this paper, measurement results for the magnetization (BH) curves of a range of sintered heavy tungsten alloys used in radiation shielding and collimation are presented. Methods: Sintered heavy tungsten alloys typically contain >90 % tungsten and <10 % of a combination of iron, nickel, and copper binders. Samples of eight different grades of sintered heavy tungsten alloys with varying binder content were investigated. Using a superconducting quantum interference detector magnetometer, the induced magnetic momentm was measured for each sample as a function of applied external field H{sub 0} and the BH curve derived. Results: The iron content of the alloys was found to play a dominant role, directly influencing the magnetizationM and thus the nonlinearity of the BH curve. Generally, the saturation magnetization increased with increasing iron content of the alloy. Furthermore, no measurable magnetization was found for all alloys without iron content, despite containing up to 6% of nickel. For two samples from different manufacturers but with identical quoted nominal elemental composition (95% W, 3.5% Ni, 1.5% Fe), a relative difference in the magnetization of 11%–16% was measured. Conclusions: The measured curves show that the magnetic properties of sintered heavy tungsten alloys strongly depend on the iron content, whereas the addition of nickel in the absence of iron led to no measurable effect. Since a difference in the BH curves for two samples with identical quoted nominal composition from different manufacturers was observed, measuring of the BH curve for each individual batch of heavy tungsten alloys is advisable whenever accurate knowledge of the magnetic properties is crucial. The obtained BH curves can be used in FEM simulations to predict the magnetic impact of sintered heavy

  10. Dual source and dual detector arrays tetrahedron beam computed tomography for image guided radiotherapy

    NASA Astrophysics Data System (ADS)

    Kim, Joshua; Lu, Weiguo; Zhang, Tiezhi

    2014-02-01

    Cone-beam computed tomography (CBCT) is an important online imaging modality for image guided radiotherapy. But suboptimal image quality and the lack of a real-time stereoscopic imaging function limit its implementation in advanced treatment techniques, such as online adaptive and 4D radiotherapy. Tetrahedron beam computed tomography (TBCT) is a novel online imaging modality designed to improve on the image quality provided by CBCT. TBCT geometry is flexible, and multiple detector and source arrays can be used for different applications. In this paper, we describe a novel dual source-dual detector TBCT system that is specially designed for LINAC radiation treatment machines. The imaging system is positioned in-line with the MV beam and is composed of two linear array x-ray sources mounted aside the electrical portal imaging device and two linear arrays of x-ray detectors mounted below the machine head. The detector and x-ray source arrays are orthogonal to each other, and each pair of source and detector arrays forms a tetrahedral volume. Four planer images can be obtained from different view angles at each gantry position at a frame rate as high as 20 frames per second. The overlapped regions provide a stereoscopic field of view of approximately 10-15 cm. With a half gantry rotation, a volumetric CT image can be reconstructed having a 45 cm field of view. Due to the scatter rejecting design of the TBCT geometry, the system can potentially produce high quality 2D and 3D images with less radiation exposure. The design of the dual source-dual detector system is described, and preliminary results of studies performed on numerical phantoms and simulated patient data are presented.

  11. Dose differences in intensity-modulated radiotherapy plans calculated with pencil beam and Monte Carlo for lung SBRT.

    PubMed

    Liu, Han; Zhuang, Tingliang; Stephans, Kevin; Videtic, Gregory; Raithel, Stephen; Djemil, Toufik; Xia, Ping

    2015-01-01

    For patients with medically inoperable early-stage non-small cell lung cancer (NSCLC) treated with stereotactic body radiation therapy, early treatment plans were based on a simpler dose calculation algorithm, the pencil beam (PB) calculation. Because these patients had the longest treatment follow-up, identifying dose differences between the PB calculated dose and Monte Carlo calculated dose is clinically important for understanding of treatment outcomes. Previous studies found significant dose differences between the PB dose calculation and more accurate dose calculation algorithms, such as convolution-based or Monte Carlo (MC), mostly for three-dimensional conformal radiotherapy (3D CRT) plans. The aim of this study is to investigate whether these observed dose differences also exist for intensity-modulated radiotherapy (IMRT) plans for both centrally and peripherally located tumors. Seventy patients (35 central and 35 peripheral) were retrospectively selected for this study. The clinical IMRT plans that were initially calculated with the PB algorithm were recalculated with the MC algorithm. Among these paired plans, dosimetric parameters were compared for the targets and critical organs. When compared to MC calculation, PB calculation overestimated doses to the planning target volumes (PTVs) of central and peripheral tumors with different magnitudes. The doses to 95% of the central and peripheral PTVs were overestimated by 9.7% ± 5.6% and 12.0% ± 7.3%, respectively. This dose overestimation did not affect doses to the critical organs, such as the spinal cord and lung. In conclusion, for NSCLC treated with IMRT, dose differences between the PB and MC calculations were different from that of 3D CRT. No significant dose differences in critical organs were observed between the two calculations. PMID:26699560

  12. Megavoltage Cone Beam Computed Tomography Dose and the Necessity of Reoptimization for Imaging Dose-Integrated Intensity-Modulated Radiotherapy for Prostate Cancer

    SciTech Connect

    Akino, Yuichi; Koizumi, Masahiko; Sumida, Iori; Takahashi, Yutaka; Ogata, Toshiyuki; Ota, Seiichi; Isohashi, Fumiaki; Konishi, Koji; Yoshioka, Yasuo

    2012-04-01

    Purpose: Megavoltage cone beam computed tomography (MV-CBCT) dose can be integrated with the patient's prescription. Here, we investigated the effects of imaging dose and the necessity for additional optimization when using intensity-modulated radiotherapy (IMRT) to treat prostate cancer. Methods and Materials: An arc beam mimicking MV-CBCT was generated using XiO (version 4.50; Elekta, Stockholm, Sweden). The monitor units (MU) for dose calculation were determined by conforming the calculated dose to the dose measured using an ionization chamber. IMRT treatment plans of 22 patients with prostate cancer were retrospectively analyzed. Arc beams of 3, 5, 8, and 15 MU were added to the IMRT plans, and the dose covering 95% of the planning target volume (PTV) was normalized to the prescribed dose with (reoptimization) or without optimization (compensation). Results: PTV homogeneity and conformality changed negligibly with MV-CBCT integration. For critical organs, an imaging dose-dependent increase was observed for the mean rectal/bladder dose (D{sub mean}), and reoptimization effectively suppressed the D{sub mean} elevations. The bladder generalized equivalent uniform dose (gEUD) increased with imaging dose, and reoptimization suppressed the gEUD elevation when 5- to 15-MU CBCT were added, although rectal gEUD changed negligibly with any imaging dose. Whereas the dose elevation from the simple addition of the imaging dose uniformly increased rectal and bladder dose, the rectal D{sub mean} increase of compensation plans was due mainly to low-dose volumes. In contrast, bladder high-dose volumes were increased by integrating the CBCT dose, and reoptimization reduced them when 5- to 15-MU CBCT were added. Conclusion: Reoptimization is clearly beneficial for reducing dose to critical organs, elevated by addition of high-MU CBCT, especially for the bladder. For low-MU CBCT aimed at bony structure visualization, compensation is sufficient.

  13. AFM and uni-axial testing of pericardium exposed to radiotherapy doses

    NASA Astrophysics Data System (ADS)

    Daar, Eman; Kaabar, W.; Lei, C.; Keddie, J. L.; Nisbet, A.; Bradley, D. A.

    2011-10-01

    The pericardium, a double-layered sac that encloses the heart, is made up of collagen and elastin fibres embedded in an amorphous matrix (forming the extracellular matrix). Collagen fibres are aligned in multidirectional orientation layers. This free arrangement of fibres gives the pericardium its viscoelastic properties and the ability to deform in all directions. This is an important mechanical property for the heart to perform its physiological functions, acknowledging the fact that the heart is attached to different ligaments and muscles in all directions. The present study aims to investigate the effect of penetrating photon ionising radiation on bovine pericardium tissue. This links to an interest in seeking to understand possible mechanisms underlying cardiac complications following treatment of the left breast in radiotherapy regimes. Pericardium samples were subjected to doses in the range 0-80 Gy. Atomic force microscopy (AFM) has been applied in characterising changes in the infrastructural and mechanical properties of the tissues. Preliminary data for doses of 80 Gy shows there was no significant change in the D-spacing period of the banded structure collagen type I but a significant increase is observed in the FWHM of the fibril widths (by between 25% and 27%) over that of unirradiated pericardium tissue.

  14. Peregrine monte carlo dose calculations for radiotherapy using clinically realistic neutron and proton beams

    SciTech Connect

    Cox, L. J., LLNL

    1997-06-16

    Lawrence Livermore National Laboratory (LLNL) has developed an all-particle Monte Carlo radiotherapy dose calculation code--PEREGRINE--for use in clinical radiation oncology. For PEREGRINE, we have assembled high-energy evaluated nuclear databases; created radiation source characterization and sampling algorithms; and simulated and characterized clinical beams for treatment with photons, neutrons and protons. Spectra are available for the Harper Hospital (Detroit, U.S.A.) Be(d,n) neutron therapy beam, the National Accelerator Centre (NAC, Faure, S.A.) Be(p,n) neutron therapy beam and many of the operating modes of the Loma Linda University Medical Center (LLUMC, Loma Linda, USA) proton treatment center. These beam descriptions are being used in PEREGRINE for Monte Carlo dose calculations on clinical configurations for comparisons to measurements. The methods of defining and sampling the beam phase space characterizations are discussed. We show calculations using these clinical beams compared to measurements in homogeneous water phantoms. The state of PEREGRINE's high energy neutron and proton transport database, PCSL, is reviewed and the remaining issues involving nuclear data needs for PEREGRINE are addressed.

  15. Critical dose and toxicity index of organs at risk in radiotherapy: Analyzing the calculated effects of modified dose fractionation in non–small cell lung cancer

    SciTech Connect

    Pedicini, Piernicola; Strigari, Lidia; Benassi, Marcello; Caivano, Rocchina; Fiorentino, Alba; Nappi, Antonio; Salvatore, Marco; Storto, Giovanni

    2014-04-01

    To increase the efficacy of radiotherapy for non–small cell lung cancer (NSCLC), many schemes of dose fractionation were assessed by a new “toxicity index” (I), which allows one to choose the fractionation schedules that produce less toxic treatments. Thirty-two patients affected by non resectable NSCLC were treated by standard 3-dimensional conformal radiotherapy (3DCRT) with a strategy of limited treated volume. Computed tomography datasets were employed to re plan by simultaneous integrated boost intensity-modulated radiotherapy (IMRT). The dose distributions from plans were used to test various schemes of dose fractionation, in 3DCRT as well as in IMRT, by transforming the dose-volume histogram (DVH) into a biological equivalent DVH (BDVH) and by varying the overall treatment time. The BDVHs were obtained through the toxicity index, which was defined for each of the organs at risk (OAR) by a linear quadratic model keeping an equivalent radiobiological effect on the target volume. The less toxic fractionation consisted in a severe/moderate hyper fractionation for the volume including the primary tumor and lymph nodes, followed by a hypofractionation for the reduced volume of the primary tumor. The 3DCRT and IMRT resulted, respectively, in 4.7% and 4.3% of dose sparing for the spinal cord, without significant changes for the combined-lungs toxicity (p < 0.001). Schedules with reduced overall treatment time (accelerated fractionations) led to a 12.5% dose sparing for the spinal cord (7.5% in IMRT), 8.3% dose sparing for V{sub 20} in the combined lungs (5.5% in IMRT), and also significant dose sparing for all the other OARs (p < 0.001). The toxicity index allows to choose fractionation schedules with reduced toxicity for all the OARs and equivalent radiobiological effect for the tumor in 3DCRT, as well as in IMRT, treatments of NSCLC.

  16. Consolidation Radiotherapy in Primary Central Nervous System Lymphomas: Impact on Outcome of Different Fields and Doses in Patients in Complete Remission After Upfront Chemotherapy

    SciTech Connect

    Ferreri, Andres Jose Maria; Verona, Chiara; Politi, Letterio Salvatore; Chiara, Anna; Perna, Lucia; Villa, Eugenio; Reni, Michele

    2011-05-01

    Purpose: Avoidance radiotherapy or reduction of irradiation doses in patients with primary central nervous system lymphoma (PCNSL) in complete remission (CR) after high-dose methotrexate (HD-MTX)-based chemotherapy has been proposed to minimize the neurotoxicity risk. Nevertheless, no study has focused on the survival impact of radiation parameters, as far as we know, and the optimal radiation schedule remains to be defined. Methods and Materials: The impact on outcome and neurologic performance of different radiation fields and doses was assessed in 33 patients with PCNSL who achieved CR after MTX-containing chemotherapy and were referred to consolidation whole-brain irradiation (WBRT). Patterns of relapse were analyzed on computed tomography-guided treatment planning, and neurologic impairment was assessed by the Mini Mental Status Examination. Results: At a median follow-up of 50 months, 21 patients are relapse-free (5-year failure-free survival [FFS], 51%). WBRT doses {>=}40 Gy were not associated with improved disease control in comparison with a WBRT dose of 30 to 36 Gy (relapse rate, 46% vs. 30%; 5-year FFS, 51% vs. 50%; p = 0.26). Disease control was not significantly different between patients irradiated to the tumor bed with 45 to 54 Gy or with 36 to 44 Gy, with a 5-year FFS of 35% and 44% (p = 0.43), respectively. Twenty patients are alive (5-year overall survival, 54%); WB and tumor bed doses did not have an impact on survival. Impairment as assessed by the Mini Mental Status Examination was significantly more common in patients treated with a WBRT dose {>=}40 Gy. Conclusion: Consolidation with WBRT 36 Gy is advisable in patients with PCNSL in CR after HD-MTX-based chemotherapy. Higher doses do not change the outcome and could increase the risk of neurotoxicity.

  17. Results of the Phase I Dose-Escalating Study of Motexafin Gadolinium With Standard Radiotherapy in Patients With Glioblastoma Multiforme

    SciTech Connect

    Ford, Judith M. Seiferheld, Wendy; Alger, Jeffrey R.; Wu, Genevieve; Endicott, Thyra J.; Mehta, Minesh; Curran, Walter; Phan, See-Chun

    2007-11-01

    Purpose: Motexafin gadolinium (MGd) is a putative radiation enhancer initially evaluated in patients with brain metastases. This Phase I trial studied the safety and tolerability of a 2-6-week course (10-22 doses) of MGd with radiotherapy for glioblastoma multiforme. Methods and Materials: A total of 33 glioblastoma multiforme patients received one of seven MGd regimens starting at 10 doses of 4 mg/kg/d MGd and escalating to 22 doses of 5.3 mg/kg/d MGd (5 or 10 daily doses then three times per week). The National Cancer Institute Cancer Therapy Evaluation Program toxicity and stopping rules were applied. Results: The maximal tolerated dose was 5.0 mg/kg/d MGd (5 d/wk for 2 weeks, then three times per week) for 22 doses. The dose-limiting toxicity was reversible transaminase elevation. Adverse reactions included rash/pruritus (45%), chills/fever (30%), and self-limiting vesiculobullous rash of the thumb and fingers (42%). The median survival of 17.6 months prompted a case-matched analysis. In the case-matched analysis, the MGd patients had a median survival of 16.1 months (n = 31) compared with the matched Radiation Therapy Oncology Group database patients with a median survival of 11.8 months (hazard ratio, 0.43; 95% confidence interval, 0.20-0.94). Conclusion: The maximal tolerated dose of MGd with radiotherapy for glioblastoma multiforme in this study was 5 mg/kg/d for 22 doses (daily for 2 weeks, then three times weekly). The baseline survival calculations suggest progression to Phase II trials is appropriate, with the addition of MGd to radiotherapy with concurrent and adjuvant temozolomide.

  18. Measurement of skin and target dose in post-mastectomy radiotherapy using 4 and 6 MV photon beams

    PubMed Central

    2013-01-01

    Background For patients with high risk breast cancer and mastectomy, radiotherapy is the treatment of choice to improve survival and local control. Target dose is mainly limited due to skin reactions. The feasibility of using 4 MV beams for chest wall treatment was studied and compared to standard 6 MV bolus radiotherapy. Methods Post-mastectomy IMRT was planned on an Alderson-phantom using 4 and 6 MV photon beams without/with a 0.5 cm thick bolus. Dose was measured using TLDs placed at 8 locations in 1 and 3 mm depth to represent skin and superficial target dose, respectively. Results 4 MV and 6 MV beams with bolus perform equally regarding target coverage. The minimum and mean superficial target dose for the 6 MV and 4 MV were 93.0% and 94.7%, and 93.1% and 94.4%, respectively. Regarding skin dose the 4 MV photon beam was advantageous. The minimum and mean skin dose for the 6 MV and 4 MV was 76.7% and 81.6%, and 69.4% and 72.9%, respectively. The TPS was able to predict dose in the build-up region with a precision of around 5%. Conclusions The use of 4 MV photon beams are a good alternative for treating the thoracic wall without the need to place a bolus on the patient. The main limitation of 4 MV beams is the limited dose rate. PMID:24238366

  19. Red bone marrow dose calculations in radiotherapy of prostate cancer based on the updated VCH adult male phantom

    NASA Astrophysics Data System (ADS)

    Ai, Jinqin; Xie, Tianwu; Sun, Wenjuan; Liu, Qian

    2014-04-01

    Red bone marrow (RBM) is an important dose-limiting tissue that has high radiosensitivity but is difficult to identify on clinical medical images. In this study, we investigated dose distribution in RBM for prostate cancer radiotherapy. Four suborgans were identified in the skeleton of the visible Chinese human phantom: cortical bone (CB), trabecular bone (TB), RBM, and yellow bone marrow (YBM). Dose distributions in the phantom were evaluated by the Monte Carlo method. When the left os coxae was taken as the organ-at-risk (OAR), the difference in absorbed dose between RBM and each CB and TB was up to 20%, but was much less (≤3.1%) between RBM and YBM. When the left os coxae and entire bone were both taken as OARs, RBM dose also increased with increasing planning target volume size. The results indicate the validity of using dose to homogeneous bone marrow mixture for estimating dose to RBM when RBM is not available in computational phantoms. In addition, the human skeletal system developed in this study provides a model for considering RBM dose in radiotherapy planning.

  20. Outcomes of visual acuity in carbon ion radiotherapy: Analysis of dose-volume histograms and prognostic factors

    SciTech Connect

    Hasegawa, Azusa . E-mail: azusa@nirs.go.jp; Mizoe, Jun-etsu; Mizota, Atsushi; Tsujii, Hirohiko

    2006-02-01

    Purpose: To analyze the tolerance dose for retention of visual acuity in patients with head-and-neck tumors treated with carbon ion radiotherapy. Methods and Materials: From June 1994 to March 2000, 163 patients with tumors in the head and neck or skull base region were treated with carbon ion radiotherapy. Analysis was performed on 54 optic nerves (ONs) corresponding to 30 patients whose ONs had been included in the irradiated volume. These patients showed no evidence of visual impairment due to other factors and had a follow-up period of >4 years. All patients had been informed of the possibility of visual impairment before treatment. We evaluated the dose-complication probability and the prognostic factors for the retention of visual acuity in carbon ion radiotherapy, using dose-volume histograms and multivariate analysis. Results: The median age of 30 patients (14 men, 16 women) was 57.2 years. Median prescribed total dose was 56.0 gray equivalents (GyE) at 3.0-4.0 GyE per fraction per day (range, 48-64 GyE; 16-18 fractions; 4-6 weeks). Of 54 ONs that were analyzed, 35 had been irradiated with <57 GyE (maximum dose [D{sub max}]) resulting in no visual loss. Conversely, 11 of the 19 ONs (58%) irradiated with >57 GyE (D{sub max}) suffered a decrease of visual acuity. In all of these cases, the ONs had been involved in the tumor before carbon ion radiotherapy. In the multivariate analysis, a dose of 20% of the volume of the ON (D{sub 2}) was significantly associated with visual loss. Conclusions: The occurrence of visual loss seems to be correlated with a delivery of >60 GyE to 20% of the volume of the ON.

  1. Dose-Dependent Pulmonary Toxicity After Postoperative Intensity-Modulated Radiotherapy for Malignant Pleural Mesothelioma

    SciTech Connect

    Rice, David C. Smythe, W. Roy; Liao Zhongxing; Guerrero, Thomas; Chang, Joe Y.; McAleer, Mary F.; Jeter, Melenda D.; Correa, Arlene Ph.D.; Vaporciyan, Ara A.; Liu, H. Helen; Komaki, Ritsuko; Forster, Kenneth M.; Stevens, Craig W.

    2007-10-01

    Purpose: To determine the incidence of fatal pulmonary events after extrapleural pneumonectomy and hemithoracic intensity-modulated radiotherapy (IMRT) for malignant pleural mesothelioma. Methods and Materials: We retrospectively reviewed the records of 63 consecutive patients with malignant pleural mesothelioma who underwent extrapleural pneumonectomy and IMRT at University of Texas M. D. Anderson Cancer Center. The endpoints studied were pulmonary-related death (PRD) and non-cancer-related death within 6 months of IMRT. Results: Of the 63 patients, 23 (37%) had died within 6 months of IMRT (10 of recurrent cancer, 6 of pulmonary causes [pneumonia in 4 and pneumonitis in 2], and 7 of other noncancer causes [pulmonary embolus in 2, sepsis after bronchopleural fistula in 1, and cause unknown but without pulmonary symptoms or recurrent disease in 4]). On univariate analysis, the factors that predicted for PRD were a lower preoperative ejection fraction (p = 0.021), absolute volume of lung spared at 10 Gy (p = 0.025), percentage of lung volume receiving {>=}20 Gy (V{sub 20}; p 0.002), and mean lung dose (p = 0.013). On multivariate analysis, only V{sub 20} was predictive of PRD (p = 0.017; odds ratio, 1.50; 95% confidence interval, 1.08-2.08) or non-cancer-related death (p = 0.033; odds ratio, 1.21; 95% confidence interval, 1.02-1.45). Conclusion: The results of our study have shown that fatal pulmonary toxicities were associated with radiation to the contralateral lung. V{sub 20} was the only independent determinant for risk of PRD or non-cancer-related death. The mean V{sub 20} of the non-PRD patients was considerably lower than that accepted during standard thoracic radiotherapy, implying that the V{sub 20} should be kept as low as possible after extrapleural pneumonectomy.

  2. Image-guided adaptive gating of lung cancer radiotherapy: a computer simulation study

    NASA Astrophysics Data System (ADS)

    Aristophanous, Michalis; Rottmann, Joerg; Park, Sang-June; Nishioka, Seiko; Shirato, Hiroki; Berbeco, Ross I.

    2010-08-01

    The purpose of this study is to investigate the effect that image-guided adaptation of the gating window during treatment could have on the residual tumor motion, by simulating different gated radiotherapy techniques. There are three separate components of this simulation: (1) the 'Hokkaido Data', which are previously measured 3D data of lung tumor motion tracks and the corresponding 1D respiratory signals obtained during the entire ungated radiotherapy treatments of eight patients, (2) the respiratory gating protocol at our institution and the imaging performed under that protocol and (3) the actual simulation in which the Hokkaido Data are used to select tumor position information that could have been collected based on the imaging performed under our gating protocol. We simulated treatments with a fixed gating window and a gating window that is updated during treatment. The patient data were divided into different fractions, each with continuous acquisitions longer than 2 min. In accordance to the imaging performed under our gating protocol, we assume that we have tumor position information for the first 15 s of treatment, obtained from kV fluoroscopy, and for the rest of the fractions the tumor position is only available during the beam-on time from MV imaging. The gating window was set according to the information obtained from the first 15 s such that the residual motion was less than 3 mm. For the fixed gating window technique the gate remained the same for the entire treatment, while for the adaptive technique the range of the tumor motion during beam-on time was measured and used to adapt the gating window to keep the residual motion below 3 mm. The algorithm used to adapt the gating window is described. The residual tumor motion inside the gating window was reduced on average by 24% for the patients with regular breathing patterns and the difference was statistically significant (p-value = 0.01). The magnitude of the residual tumor motion depended on the

  3. Dose-Effect Relationships for the Submandibular Salivary Glands and Implications for Their Sparing by Intensity Modulated Radiotherapy

    PubMed Central

    Murdoch-Kinch, Carol-Anne; Kim, Hyugnjin M.; Vineberg, Karen A; Ship, Jonathan A.; Eisbruch, Avraham

    2012-01-01

    Purpose Submandibular salivary glands (SMGs) dysfunction contributes to xerostomia after radiotherapy (RT) of head and neck (HN) cancer. We assessed SMG dose-response relationships and their implications for sparing these glands by intensity modulated radiotherapy (IMRT). Patients and Methods 148 HN cancer patients underwent unstimulated and stimulated SMG salivary flow rate measurements selectively from Wharton’s duct orifices, before RT and periodically through 24 months after RT. Correlations of flow rates and mean SMG doses were modeled throughout all time points. IMRT re-planning in eight patients whose contralateral level I was not a target incorporated the results in a new cost function aiming to spare contralateral SMGs. Results Stimulated SMG flow rates decreased exponentially by (1.2%)Gy as mean doses increased up to 39 Gy threshold, and then plateaued near zero. At mean doses ≤39 Gy, but not higher, flow rates recovered over time at 2.2%/month. Similarly, the unstimulated salivary flow rates decreased exponentially by (3%)Gy as mean dose increased and recovered over time if mean dose was <39 Gy. IMRT re-planning reduced mean contralateral SMG dose by average 12 Gy, achieving ≤39 Gy in 5/8 patients, without target under-dosing, increasing the mean doses to the parotid glands and swallowing structures by average 2–3 Gy. Conclusions SMG salivary flow rates depended on mean dose with recovery over time up to a threshold of 39 Gy. Substantial SMG dose reduction to below this threshold and without target under-dosing is feasible in some patients, at the expense of modestly higher doses to some other organs. PMID:18337023

  4. A comparison between anisotropic analytical and multigrid superposition dose calculation algorithms in radiotherapy treatment planning.

    PubMed

    Wu, Vincent W C; Tse, Teddy K H; Ho, Cola L M; Yeung, Eric C Y

    2013-01-01

    Monte Carlo (MC) simulation is currently the most accurate dose calculation algorithm in radiotherapy planning but requires relatively long processing time. Faster model-based algorithms such as the anisotropic analytical algorithm (AAA) by the Eclipse treatment planning system and multigrid superposition (MGS) by the XiO treatment planning system are 2 commonly used algorithms. This study compared AAA and MGS against MC, as the gold standard, on brain, nasopharynx, lung, and prostate cancer patients. Computed tomography of 6 patients of each cancer type was used. The same hypothetical treatment plan using the same machine and treatment prescription was computed for each case by each planning system using their respective dose calculation algorithm. The doses at reference points including (1) soft tissues only, (2) bones only, (3) air cavities only, (4) soft tissue-bone boundary (Soft/Bone), (5) soft tissue-air boundary (Soft/Air), and (6) bone-air boundary (Bone/Air), were measured and compared using the mean absolute percentage error (MAPE), which was a function of the percentage dose deviations from MC. Besides, the computation time of each treatment plan was recorded and compared. The MAPEs of MGS were significantly lower than AAA in all types of cancers (p<0.001). With regards to body density combinations, the MAPE of AAA ranged from 1.8% (soft tissue) to 4.9% (Bone/Air), whereas that of MGS from 1.6% (air cavities) to 2.9% (Soft/Bone). The MAPEs of MGS (2.6%±2.1) were significantly lower than that of AAA (3.7%±2.5) in all tissue density combinations (p<0.001). The mean computation time of AAA for all treatment plans was significantly lower than that of the MGS (p<0.001). Both AAA and MGS algorithms demonstrated dose deviations of less than 4.0% in most clinical cases and their performance was better in homogeneous tissues than at tissue boundaries. In general, MGS demonstrated relatively smaller dose deviations than AAA but required longer computation time

  5. GPU-based Monte Carlo radiotherapy dose calculation using phase-space sources

    NASA Astrophysics Data System (ADS)

    Townson, Reid W.; Jia, Xun; Tian, Zhen; Jiang Graves, Yan; Zavgorodni, Sergei; Jiang, Steve B.

    2013-06-01

    A novel phase-space source implementation has been designed for graphics processing unit (GPU)-based Monte Carlo dose calculation engines. Short of full simulation of the linac head, using a phase-space source is the most accurate method to model a clinical radiation beam in dose calculations. However, in GPU-based Monte Carlo dose calculations where the computation efficiency is very high, the time required to read and process a large phase-space file becomes comparable to the particle transport time. Moreover, due to the parallelized nature of GPU hardware, it is essential to simultaneously transport particles of the same type and similar energies but separated spatially to yield a high efficiency. We present three methods for phase-space implementation that have been integrated into the most recent version of the GPU-based Monte Carlo radiotherapy dose calculation package gDPM v3.0. The first method is to sequentially read particles from a patient-dependent phase-space and sort them on-the-fly based on particle type and energy. The second method supplements this with a simple secondary collimator model and fluence map implementation so that patient-independent phase-space sources can be used. Finally, as the third method (called the phase-space-let, or PSL, method) we introduce a novel source implementation utilizing pre-processed patient-independent phase-spaces that are sorted by particle type, energy and position. Position bins located outside a rectangular region of interest enclosing the treatment field are ignored, substantially decreasing simulation time with little effect on the final dose distribution. The three methods were validated in absolute dose against BEAMnrc/DOSXYZnrc and compared using gamma-index tests (2%/2 mm above the 10% isodose). It was found that the PSL method has the optimal balance between accuracy and efficiency and thus is used as the default method in gDPM v3.0. Using the PSL method, open fields of 4 × 4, 10 × 10 and 30 × 30 cm

  6. GPU-based Monte Carlo radiotherapy dose calculation using phase-space sources.

    PubMed

    Townson, Reid W; Jia, Xun; Tian, Zhen; Graves, Yan Jiang; Zavgorodni, Sergei; Jiang, Steve B

    2013-06-21

    A novel phase-space source implementation has been designed for graphics processing unit (GPU)-based Monte Carlo dose calculation engines. Short of full simulation of the linac head, using a phase-space source is the most accurate method to model a clinical radiation beam in dose calculations. However, in GPU-based Monte Carlo dose calculations where the computation efficiency is very high, the time required to read and process a large phase-space file becomes comparable to the particle transport time. Moreover, due to the parallelized nature of GPU hardware, it is essential to simultaneously transport particles of the same type and similar energies but separated spatially to yield a high efficiency. We present three methods for phase-space implementation that have been integrated into the most recent version of the GPU-based Monte Carlo radiotherapy dose calculation package gDPM v3.0. The first method is to sequentially read particles from a patient-dependent phase-space and sort them on-the-fly based on particle type and energy. The second method supplements this with a simple secondary collimator model and fluence map implementation so that patient-independent phase-space sources can be used. Finally, as the third method (called the phase-space-let, or PSL, method) we introduce a novel source implementation utilizing pre-processed patient-independent phase-spaces that are sorted by particle type, energy and position. Position bins located outside a rectangular region of interest enclosing the treatment field are ignored, substantially decreasing simulation time with little effect on the final dose distribution. The three methods were validated in absolute dose against BEAMnrc/DOSXYZnrc and compared using gamma-index tests (2%/2 mm above the 10% isodose). It was found that the PSL method has the optimal balance between accuracy and efficiency and thus is used as the default method in gDPM v3.0. Using the PSL method, open fields of 4 × 4, 10 × 10 and 30 × 30 cm

  7. A comparison between anisotropic analytical and multigrid superposition dose calculation algorithms in radiotherapy treatment planning

    SciTech Connect

    Wu, Vincent W.C.; Tse, Teddy K.H.; Ho, Cola L.M.; Yeung, Eric C.Y.

    2013-07-01

    Monte Carlo (MC) simulation is currently the most accurate dose calculation algorithm in radiotherapy planning but requires relatively long processing time. Faster model-based algorithms such as the anisotropic analytical algorithm (AAA) by the Eclipse treatment planning system and multigrid superposition (MGS) by the XiO treatment planning system are 2 commonly used algorithms. This study compared AAA and MGS against MC, as the gold standard, on brain, nasopharynx, lung, and prostate cancer patients. Computed tomography of 6 patients of each cancer type was used. The same hypothetical treatment plan using the same machine and treatment prescription was computed for each case by each planning system using their respective dose calculation algorithm. The doses at reference points including (1) soft tissues only, (2) bones only, (3) air cavities only, (4) soft tissue-bone boundary (Soft/Bone), (5) soft tissue-air boundary (Soft/Air), and (6) bone-air boundary (Bone/Air), were measured and compared using the mean absolute percentage error (MAPE), which was a function of the percentage dose deviations from MC. Besides, the computation time of each treatment plan was recorded and compared. The MAPEs of MGS were significantly lower than AAA in all types of cancers (p<0.001). With regards to body density combinations, the MAPE of AAA ranged from 1.8% (soft tissue) to 4.9% (Bone/Air), whereas that of MGS from 1.6% (air cavities) to 2.9% (Soft/Bone). The MAPEs of MGS (2.6%±2.1) were significantly lower than that of AAA (3.7%±2.5) in all tissue density combinations (p<0.001). The mean computation time of AAA for all treatment plans was significantly lower than that of the MGS (p<0.001). Both AAA and MGS algorithms demonstrated dose deviations of less than 4.0% in most clinical cases and their performance was better in homogeneous tissues than at tissue boundaries. In general, MGS demonstrated relatively smaller dose deviations than AAA but required longer computation time.

  8. Site-specific dose-response relationships for cancer induction from the combined Japanese A-bomb and Hodgkin cohorts for doses relevant to radiotherapy

    PubMed Central

    2011-01-01

    Background and Purpose Most information on the dose-response of radiation-induced cancer is derived from data on the A-bomb survivors. Since, for radiation protection purposes, the dose span of main interest is between zero and one Gy, the analysis of the A-bomb survivors is usually focused on this range. However, estimates of cancer risk for doses larger than one Gy are becoming more important for radiotherapy patients. Therefore in this work, emphasis is placed on doses relevant for radiotherapy with respect to radiation induced solid cancer. Materials and methods For various organs and tissues the analysis of cancer induction was extended by an attempted combination of the linear-no-threshold model from the A-bomb survivors in the low dose range and the cancer risk data of patients receiving radiotherapy for Hodgkin's disease in the high dose range. The data were fitted using organ equivalent dose (OED) calculated for a group of different dose-response models including a linear model, a model including fractionation, a bell-shaped model and a plateau-dose-response relationship. Results The quality of the applied fits shows that the linear model fits best colon, cervix and skin. All other organs are best fitted by the model including fractionation indicating that the repopulation/repair ability of tissue is neither 0 nor 100% but somewhere in between. Bone and soft tissue sarcoma were fitted well by all the models. In the low dose range beyond 1 Gy sarcoma risk is negligible. For increasing dose, sarcoma risk increases rapidly and reaches a plateau at around 30 Gy. Conclusions In this work OED for various organs was calculated for a linear, a bell-shaped, a plateau and a mixture between a bell-shaped and plateau dose-response relationship for typical treatment plans of Hodgkin's disease patients. The model parameters (α and R) were obtained by a fit of the dose-response relationships to these OED data and to the A-bomb survivors. For any three

  9. Early-onset dropped head syndrome after radiotherapy for head and neck cancer: dose constraints for neck extensor muscles

    PubMed Central

    Inaba, Koji; Nakamura, Satoshi; Okamoto, Hiroyuki; Kashihara, Tairo; Kobayashi, Kazuma; Harada, Ken; Kitaguchi, Mayuka; Sekii, Shuhei; Takahashi, Kana; Murakami, Naoya; Ito, Yoshinori; Igaki, Hiroshi; Uno, Takashi; Itami, Jun

    2016-01-01

    Dropped head syndrome (DHS) is a famous but unusual late complication of multimodality treatment for head and neck carcinoma. We reported this early-onset complication and analyzed the dose to the neck extensor muscles. We examined the records of three patients with DHS after radiotherapy. The doses to the neck extensor muscles were compared between three patients with DHS and nine patients without DHS. The mean dose to the neck extensor muscles of the three patients with DHS were 58.5 Gy, 42.3 Gy and 60.9 Gy, while the dose was <50 Gy in all nine patients in the control group. The onset of this syndrome was 5 months, 6 months and 15 months. The early-onset DHS may have something to do with dose to the neck extensor muscles. The proposed dose to the neck extensor muscles might be <46 Gy (or at least <50 Gy). PMID:26684338

  10. The Effect of Changing Technique, Dose, and PTV Margin on Therapeutic Ratio During Prostate Radiotherapy

    SciTech Connect

    Huang Shaohui; Catton, Charles; Jezioranski, John M.Math.; Bayley, Andrew; Rose, Stuart; Rosewall, Tara

    2008-07-15

    Purpose: To quantify the dosimetric and radiobiological changes seen when using intensity-modulated radiation therapy (IMRT) or planning target volume (PTV) margin reduction with consistent planning parameters in a representative sample of localized prostate cancer patients. Methods and Materials: Twenty patients were randomly selected from a cohort that received 79.8 Gy using six-field conformal radiotherapy. Using the clinical contours, PTV margin, planning system, and dose constraints, five-field IMRT plans were generated for 79.8, 83.8, and 88.0 Gy. The 88.0-Gy IMRT plan was then reoptimized with a PTV margin reduced to 3 mm. These plans were then compared using various dosimetric and radiobiological endpoints calculated for various {alpha}/{beta}. Results: Intensity-modulated RT resulted in greater conformity to the PTV (p < 0.001). No improvement in mean normal tissue complication probabilities in the rectal wall (NTCPrw) was seen, and the modified therapeutic ratio (TR{sub mod}) was largely unchanged between six-field conformal and IMRT for the majority of the patients. When IMRT was used to escalate dose, NTCPrw increased by 9% at each 5% prescription increase (p < 0.001). Reducing the posterior PTV margin from 7 mm to 3 mm for an IMRT plan reduced the mean NTCPrw by 12% (p < 0.001) and resulted in a trend toward increased TR{sub mod}(p = 0.005). Changes in TR{sub mod} between conformal and IMRT planning or PTV reduction showed large interpatient variability. Conclusions: Changing from conformal to IMRT, or from PTV{sub 10-7} to PTV{sub 3}, did not produce a uniform interpatient increase in TR{sub mod}when the CTV contained the prostate alone. Radiobiological benefits of these two methods seem to be dependent on the particular anatomy of individual patients, supporting the use of patient-specific margin, planning, and dose prescription strategies.

  11. Brain Magnetic Resonance Imaging After High-Dose Chemotherapy and Radiotherapy for Childhood Brain Tumors

    SciTech Connect

    Spreafico, Filippo Gandola, Lorenza; Marchiano, Alfonso; Simonetti, Fabio; Poggi, Geraldina; Adduci, Anna; Clerici, Carlo Alfredo; Luksch, Roberto; Biassoni, Veronica; Meazza, Cristina; Catania, Serena; Terenziani, Monica; Musumeci, Renato; Fossati-Bellani, Franca; Massimino, Maura

    2008-03-15

    Purpose: Brain necrosis or other subacute iatrogenic reactions has been recognized as a potential complication of radiotherapy (RT), although the possible synergistic effects of high-dose chemotherapy and RT might have been underestimated. Methods and Materials: We reviewed the clinical and radiologic data of 49 consecutive children with malignant brain tumors treated with high-dose thiotepa and autologous hematopoietic stem cell rescue, preceded or followed by RT. The patients were assessed for neurocognitive tests to identify any correlation with magnetic resonance imaging (MRI) anomalies. Results: Of the 49 children, 18 (6 of 25 with high-grade gliomas and 12 of 24 with primitive neuroectodermal tumors) had abnormal brain MRI findings occurring a median of 8 months (range, 2-39 months) after RT and beginning to regress a median of 13 months (range, 2-26 months) after onset. The most common lesion pattern involved multiple pseudonodular, millimeter-size, T{sub 1}-weighted unevenly enhancing, and T{sub 2}-weighted hyperintense foci. Four patients with primitive neuroectodermal tumors also had subdural fluid leaks, with meningeal enhancement over the effusion. One-half of the patients had symptoms relating to the new radiographic findings. The MRI lesion-free survival rate was 74% {+-} 6% at 1 year and 57% {+-} 8% at 2 years. The number of marrow ablative courses correlated significantly to the incidence of radiographic anomalies. No significant difference was found in intelligent quotient scores between children with and without radiographic changes. Conclusion: Multiple enhancing cerebral lesions were frequently seen on MRI scans soon after high-dose chemotherapy and RT. Such findings pose a major diagnostic challenge in terms of their differential diagnosis vis-a-vis recurrent tumor. Their correlation with neurocognitive results deserves further investigation.

  12. Robotic Image-Guided Stereotactic Radiotherapy, for Isolated Recurrent Primary, Lymph Node or Metastatic Prostate Cancer

    SciTech Connect

    Jereczek-Fossa, Barbara Alicja; Beltramo, Giancarlo; Fariselli, Laura; Fodor, Cristiana; Santoro, Luigi; Vavassori, Andrea; Zerini, Dario; Gherardi, Federica; Ascione, Carmen; Bossi-Zanetti, Isa; Mauro, Roberta; Bregantin, Achille; Bianchi, Livia Corinna; De Cobelli, Ottavio; Orecchia, Roberto

    2012-02-01

    Purpose: To evaluate the outcome of robotic CyberKnife (Accuray, Sunnyvale, CA)-based stereotactic radiotherapy (CBK-SRT) for isolated recurrent primary, lymph node, or metastatic prostate cancer. Methods and Materials: Between May 2007 and December 2009, 34 consecutive patients/38 lesions were treated (15 patients reirradiated for local recurrence [P], 4 patients reirradiated for anastomosis recurrence [A], 16 patients treated for single lymph node recurrence [LN], and 3 patients treated for single metastasis [M]). In all but 4 patients, [{sup 11}C]choline positron emission tomography/computed tomography was performed. CBK-SRT consisted of reirradiation and first radiotherapy in 27 and 11 lesions, respectively. The median CBK-SRT dose was 30 Gy in 4.5 fractions (P, 30 Gy in 5 fractions; A, 30 Gy in 5 fractions; LN, 33 Gy in 3 fractions; and M, 36 Gy in 3 fractions). In 18 patients (21 lesions) androgen deprivation was added to CBK-SRT (median duration, 16.6 months). Results: The median follow-up was 16.9 months. Acute toxicity included urinary events (3 Grade 1, 2 Grade 2, and 2 Grade 3 events) and rectal events (1 Grade 1 event). Late toxicity included urinary events (3 Grade 1, 2 Grade 2, and 2 Grade 3 events) and rectal events (1 Grade 1 event and 1 Grade 2 event). Biochemical response was observed in 32 of 38 evaluable lesions. Prostate-specific antigen stabilization was seen for 4 lesions, and in 2 cases prostate-specific antigen progression was reported. The 30-month progression-free survival rate was 42.6%. Disease progression was observed for 14 lesions (5, 2, 5, and 2 in Groups P, A, LN, and M respectively). In only 3 cases, in-field progression was seen. At the time of analysis (May 2010), 19 patients are alive with no evidence of disease and 15 are alive with disease. Conclusions: CyberKnife-based stereotactic radiotherapy is a feasible approach for isolated recurrent primary, lymph node, or metastatic prostate cancer, offering excellent in-field tumor

  13. Three-dimensional conformal versus intensity-modulated radiotherapy dose planning in stereotactic radiotherapy: Application of standard quality parameters for plan evaluation

    SciTech Connect

    Grzadziel, Aleksandra; Grosu, Anca-Ligia . E-mail: anca-ligia.grosu@lrz.tum.de; Kneschaurek, Peter

    2006-11-15

    Purpose: The implementation of intensity-modulated radiotherapy (IMRT) technique into clinical practice is becoming routine, but still lacks a generally accepted method for plan evaluation. We present a comparison of the dose distribution of conformal three-dimensional radiotherapy plans with IMRT plans for cranial lesions in stereotactic radiotherapy. The primary aim of this study was to judge the quality of the treatment plans. The next purpose was to assess the usefulness of several quality factors for plan evaluation. Methods and Materials: Five patients, who were treated in our department, were analyzed. Four had meningioma and one had pituitary adenoma. For each case, 10 different plans were created and analyzed: 2 conventional conformal three-dimensional plans and 8 IMRT plans, using the 'step and shoot' delivery method. The first conventional plan was an individually designed beam arrangement and was used for patient treatment. The second plan was a standard plan with the same beam arrangement for all patients. Beam arrangements from the conformal plans were the base for the inversely planned IMRT. To evaluate the plans, the following factors were investigated: minimal and maximal dose to the planning target volume, homogeneity index, coverage index, conformity index, and tumor control probabilities and normal tissue complication probabilities. These quantities were incorporated into scoring factors and assigned to each plan. Results: The greatest homogeneity was reached in the conformal plans and IMRT plans with high planning target volume priority in the optimization process. This consequently led to a better probability of tumor control. Better protection of organs at risk and thereby lower normal tissue complication probabilities were achieved in the IMRT plans with increased weighting of the organs at risk. Conclusion: These results show the efficiency, as well as some limitations, of the IMRT techniques. The use of different quality factors allowed us

  14. SU-E-T-306: Study of the Reduction Technique for the Secondary Cancer Risk Due to Cone Beam CT in Image Guided Radiotherapy

    SciTech Connect

    Sung, J; Kim, D; Kim, D; Chung, W; Baek, T; Lee, H; Yoon, M

    2014-06-01

    Purpose: This study evaluated the effectiveness of a thin lead sheet based simple shielding method for imaging doses from cone beam computed tomography (CBCT) in image-guided radiotherapy (IGRT). Methods: The entire body, except for the region scanned by CBCT, was shielded by wrapping in a 2 mm lead sheet. Reduction of secondary doses from CBCT was measured using a radio-photoluminescence glass dosimeter (RPLGD) placed inside an anthropomorphic phantom and changes in secondary cancer risk due to the shielding effect were estimated using BEIR VII model. Results: Doses to out-of-field organs for head-and-neck, chest, and pelvis scans were decreased 15∼100 %, 23∼90 %, and 23∼98 %, respectively, and the average reductions in lifetime secondary cancer risk due to the 2 mm lead shielding were 1.61, 10.4, and 12.8 persons per 100,000, respectively. Conclusion: This study suggests that a simple thin lead sheet based shielding method results in a non-negligible reduction of secondary doses to out-of-field regions for CBCT.

  15. Target Coverage in Image-Guided Stereotactic Body Radiotherapy of Liver Tumors

    SciTech Connect

    Wunderink, Wouter . E-mail: w.wunderink@erasmusmc.nl; Romero, Alejandra Mendez; Osorio, Eliana M. Vasquez; Boer, Hans C.J. de; Brandwijk, Rene P.; Levendag, Peter C.; Heijmen, Ben

    2007-05-01

    Purpose: To determine the effect of image-guided procedures (with computed tomography [CT] and electronic portal images before each treatment fraction) on target coverage in stereotactic body radiotherapy for liver patients using a stereotactic body frame (SBF) and abdominal compression. CT guidance was used to correct for day-to-day variations in the tumor's mean position in the SBF. Methods and Materials: By retrospectively evaluating 57 treatment sessions, tumor coverage, as obtained with the clinically applied CT-guided protocol, was compared with that of alternative procedures. The internal target volume-plus (ITV{sup +}) was introduced to explicitly include uncertainties in tumor delineations resulting from CT-imaging artifacts caused by residual respiratory motion. Tumor coverage was defined as the volume overlap of the ITV{sup +}, derived from a tumor delineated in a treatment CT scan, and the planning target volume. Patient stability in the SBF, after acquisition of the treatment CT scan, was evaluated by measuring the displacement of the bony anatomy in the electronic portal images relative to CT. Results: Application of our clinical protocol (with setup corrections following from manual measurements of the distances between the contours of the planning target volume and the daily clinical target volume in three orthogonal planes, multiple two-dimensional) increased the frequency of nearly full ({>=}99%) ITV{sup +} coverage to 77% compared with 63% without setup correction. An automated three-dimensional method further improved the frequency to 96%. Patient displacements in the SBF were generally small ({<=}2 mm, 1 standard deviation), but large craniocaudal displacements (maximal 7.2 mm) were occasionally observed. Conclusion: Daily, CT-assisted patient setup may substantially improve tumor coverage, especially with the automated three-dimensional procedure. In the present treatment design, patient stability in the SBF should be verified with portal

  16. Development and application of a random lung model for dose calculations in radiotherapy

    NASA Astrophysics Data System (ADS)

    Liang, Liang

    Radiotherapy requires accurate dose calculations in the human body, especially in disease sites with large variations of electron density in neighboring tissues, such as the lung. Currently, the lung is modeled by a voxelized geometry interpolated from computed tomography (CT) scans to various resolutions. The simplest such voxelized lung, the atomic mix model, is a homogenized whole lung with a volume-averaged bulk density. However, according traditional transport theory, even the relatively fine CT voxelization of the lung is not valid, due to the extremely small mean free path (MFP) of the electrons. The purpose of this thesis is to study the impact of the lung's heterogeneities on dose calculations in lung treatment planning. We first extend the traditional atomic mix theory for charged particles by approximating the Boltzmann equation for electrons to its Fokker-Planck (FP) limit, and then applying a formal asymptotic analysis to the BFP equation. This analysis raises the length scale for homogenizing a heterogeneous medium from the electron mean free path (MFP) to the much larger electron transport MFP. Then, using the lung's anatomical data and our new atomic mix theory, we build a realistic 2 1/2-D random lung model. The dose distributions for representative realizations of the random lung model are compared to those from the atomic mix approximation of the random lung model, showing that significant perturbations may occur with small field sizes and large lung structures. We also apply our random lung model to a more realistic lung phantom and investigate the effect of CT resolutions on lung treatment planning. We show that, compared to the reference 1 x 1 mm2 CT resolution, a 2 x 2 mm2 CT resolution is sufficient to voxelize the lung, while significant deviations in dose can be observed with a larger 4 x 4 mm 2 CT resolution. We use the Monte Carlo method extensively in this thesis, to avoid systematic errors caused by inaccurate heterogeneity corrections

  17. Real-time 3D-surface-guided head refixation useful for fractionated stereotactic radiotherapy

    SciTech Connect

    Li Shidong; Liu Dezhi; Yin Gongjie; Zhuang Ping; Geng, Jason

    2006-02-15

    Accurate and precise head refixation in fractionated stereotactic radiotherapy has been achieved through alignment of real-time 3D-surface images with a reference surface image. The reference surface image is either a 3D optical surface image taken at simulation with the desired treatment position, or a CT/MRI-surface rendering in the treatment plan with corrections for patient motion during CT/MRI scans and partial volume effects. The real-time 3D surface images are rapidly captured by using a 3D video camera mounted on the ceiling of the treatment vault. Any facial expression such as mouth opening that affects surface shape and location can be avoided using a new facial monitoring technique. The image artifacts on the real-time surface can generally be removed by setting a threshold of jumps at the neighboring points while preserving detailed features of the surface of interest. Such a real-time surface image, registered in the treatment machine coordinate system, provides a reliable representation of the patient head position during the treatment. A fast automatic alignment between the real-time surface and the reference surface using a modified iterative-closest-point method leads to an efficient and robust surface-guided target refixation. Experimental and clinical results demonstrate the excellent efficacy of <2 min set-up time, the desired accuracy and precision of <1 mm in isocenter shifts, and <1 deg. in rotation.

  18. Real-time 3D surface-image-guided beam setup in radiotherapy of breast cancer

    SciTech Connect

    Djajaputra, David; Li Shidong

    2005-01-01

    We describe an approach for external beam radiotherapy of breast cancer that utilizes the three-dimensional (3D) surface information of the breast. The surface data of the breast are obtained from a 3D optical camera that is rigidly mounted on the ceiling of the treatment vault. This 3D camera utilizes light in the visible range therefore it introduces no ionization radiation to the patient. In addition to the surface topographical information of the treated area, the camera also captures gray-scale information that is overlaid on the 3D surface image. This allows us to visualize the skin markers and automatically determine the isocenter position and the beam angles in the breast tangential fields. The field sizes and shapes of the tangential, supraclavicular, and internal mammary gland fields can all be determined according to the 3D surface image of the target. A least-squares method is first introduced for the tangential-field setup that is useful for compensation of the target shape changes. The entire process of capturing the 3D surface data and subsequent calculation of beam parameters typically requires less than 1 min. Our tests on phantom experiments and patient images have achieved the accuracy of 1 mm in shift and 0.5 deg. in rotation. Importantly, the target shape and position changes in each treatment session can both be corrected through this real-time image-guided system.

  19. Pharmacogenetic-guided Warfarin Dosing Algorithm in African-Americans.

    PubMed

    Alzubiedi, Sameh; Saleh, Mohammad I

    2016-01-01

    We aim to develop warfarin dosing algorithm for African-Americans. We explored demographic, clinical, and genetic data from a previously collected cohort of 163 African-American patients with a stable warfarin dose. We explored 2 approaches to develop the algorithm: multiple linear regression and artificial neural network (ANN). The clinical significance of the 2 dosing algorithms was evaluated by calculating the percentage of patients whose predicted dose of warfarin was within 20% of the actual dose. Linear regression model and ANN model predicted the ideal dose in 52% and 48% of the patients, respectively. The mean absolute error using linear regression model was estimated to be 10.8 mg compared with 10.9 mg using ANN. Linear regression and ANN models identified several predictors of warfarin dose including age, weight, CYP2C9 genotype *1/*1, VKORC1 genotype, rs12777823 genotype, rs2108622 genotype, congestive heart failure, and amiodarone use. In conclusion, we developed a warfarin dosing algorithm for African-Americans. The proposed dosing algorithm has the potential to recommend warfarin doses that are close to the appropriate doses. The use of more sophisticated ANN approach did not result in improved predictive performance of the dosing algorithm except for patients of a dose of ≥49 mg/wk. PMID:26355760

  20. Nuclear-interaction correction of integrated depth dose in carbon-ion radiotherapy treatment planning.

    PubMed

    Inaniwa, T; Kanematsu, N; Hara, Y; Furukawa, T

    2015-01-01

    1% for all materials and combinations of them. In scanned beams, the dose estimation error in target dose amounted to 4% for a 150 mm-thick layer of 40% K2HPO4. The error is significantly reduced with the correction method. The planned dose distributions with the method agreed with the measurements within ±1.5% of target dose for all materials not only in the target region but also in the plateau and fragment-tail regions. We tested the correction method of IDD in some non-water materials to verify that this method would offer the accuracy and simplicity required in carbon-ion radiotherapy treatment planning. PMID:25658006

  1. Phase I Study of Conformal Radiotherapy and Concurrent Full-Dose Gemcitabine With Erlotinib for Unresected Pancreatic Cancer

    SciTech Connect

    Robertson, John M.; Margolis, Jeffrey; Jury, Robert P.; Balaraman, Savitha; Cotant, Matthew B.; Ballouz, Samer; Boxwala, Iqbal G.; Jaiyesimi, Ishmael A.; Nadeau, Laura; Hardy-Carlson, Maria; Marvin, Kimberly S.; Wallace, Michelle; Ye Hong

    2012-02-01

    Purpose: To determine the recommended dose of radiotherapy when combined with full-dose gemcitabine and erlotinib for unresected pancreas cancer. Methods and Materials: Patients with unresected pancreatic cancer (Zubrod performance status 0-2) were eligible for the present study. Gemcitabine was given weekly for 7 weeks (1,000 mg/m{sup 2}) with erlotinib daily for 8 weeks (100 mg). A final toxicity assessment was performed in Week 9. Radiotherapy (starting at 30 Gy in 2-Gy fractions, 5 d/wk) was given to the gross tumor plus a 1-cm margin starting with the first dose of gemcitabine. A standard 3 plus 3 dose escalation (an additional 4 Gy within 2 days for each dose level) was used, except for the starting dose level, which was scheduled to contain 6 patients. In general, Grade 3 or greater gastrointestinal toxicity was considered a dose-limiting toxicity, except for Grade 3 anorexia or Grade 3 fatigue alone. Results: A total of 20 patients were treated (10 men and 10 women). Nausea, vomiting, and infection were significantly associated with the radiation dose (p = .01, p = .03, and p = .03, respectively). Of the 20 patients, 5 did not complete treatment and were not evaluable for dose-escalation purposes (3 who developed progressive disease during treatment and 2 who electively discontinued it). Dose-limiting toxicity occurred in none of 6 patients at 30 Gy, 2 of 6 at 34 Gy, and 1 of 3 patients at 38 Gy. Conclusion: The results of the present study have indicated that the recommended Phase II dose is 30 Gy in 15 fractions.

  2. Dose-Effect Relationships for the Submandibular Salivary Glands and Implications for Their Sparing by Intensity Modulated Radiotherapy

    SciTech Connect

    Murdoch-Kinch, Carol-Anne; Vineberg, Karen A.; Ship, Jonathan

    2008-10-01

    Purpose: Submandibular salivary glands (SMGs) dysfunction contributes to xerostomia after radiotherapy (RT) of head-and-neck (HN) cancer. We assessed SMG dose-response relationships and their implications for sparing these glands by intensity-modulated radiotherapy (IMRT). Methods and Materials: A total of 148 HN cancer patients underwent unstimulated and stimulated SMG salivary flow rate measurements selectively from Wharton's duct orifices, before RT and periodically through 24 months after RT. Correlations of flow rates and mean SMG doses were modeled throughout all time points. IMRT replanning in 8 patients whose contralateral level I was not a target incorporated the results in a new cost function aiming to spare contralateral SMGs. Results: Stimulated SMG flow rates decreased exponentially by (1.2%){sup Gy} as mean doses increased up to 39 Gy threshold, and then plateaued near zero. At mean doses {<=}39 Gy, but not higher, flow rates recovered over time at 2.2%/month. Similarly, the unstimulated salivary flow rates decreased exponentially by (3%){sup Gy} as mean dose increased and recovered over time if mean dose was <39 Gy. IMRT replanning reduced mean contralateral SMG dose by average 12 Gy, achieving {<=}39 Gy in 5 of 8 patients, without target underdosing, increasing the mean doses to the parotid glands and swallowing structures by average 2-3 Gy. Conclusions: SMG salivary flow rates depended on mean dose with recovery over time up to a threshold of 39 Gy. Substantial SMG dose reduction to below this threshold and without target underdosing is feasible in some patients, at the expense of modestly higher doses to some other organs.

  3. Image-guided brachytherapy (IGBT) combined with whole pelvic intensity-modulated radiotherapy (WP-IMRT) for locally advanced cervical cancer: a prospective study from Chiang Mai University Hospital, Thailand

    PubMed Central

    Wanwilairat, Somsak; Chakrabandhu, Somvilai; Klunklin, Pitchayaponne; Onchan, Wimrak; Tippanya, Damrongsak; Nopnop, Wannapa; Galalae, Razvan; Chitapanarux, Imjai

    2013-01-01

    Purpose A report of preliminary results and toxicity profiles using image-guided brachytherapy (IGBT) combined with whole pelvic intensity-modulated radiation therapy (WP-IMRT) for locally advanced cervical cancer. Material and methods Fifteen patients with locally advanced cervical cancer were enrolled into the study. WP-IMRT was used to treat the Clinical Target Volume (CTV) with a dose of 45 Gy in 25 fractions. Concurrent cisplatin (40 mg/m2) was prescribed during radiotherapy (RT) on weekly basis. IGBT using computed tomography was performed at the dose of 7 Gy × 4 fractions to the High-Risk Clinical Target Volume (HR-CTV). Results The mean cumulative doses – in terms of equivalent dose of 2 Gy (EQD2) – of IGBT plus WP-IMRT to HR-CTV, bladder, rectum, and sigmoid colon were 88.3, 85.0, 68.2 and 73.6 Gy, respectively. In comparison with standard (point A prescription) dose-volume histograms, volume-based image-guided brachytherapy improved the cumulative doses for bladder of 67%, rectum of 47% and sigmoid of 46%. At the median follow-up time of 14 months, the local control, metastasis-free survival and overall survival rates were 93%, 100% and 93%, respectively. No grade 3-4 acute and late toxicities were observed. Conclusion The combination of image-guided brachytherapy and intensity-modulated radiotherapy improved the dose distribution to tumor volumes and avoided overdose in OARs which could be converted in excellent local control and toxicity profiles. PMID:23634150

  4. A Novel Dose Constraint to Reduce Xerostomia in Head-and-Neck Cancer Patients Treated With Intensity-Modulated Radiotherapy

    SciTech Connect

    Strigari, Lidia; Benassi, Marcello; Arcangeli, Giorgio; Bruzzaniti, Vicente; Giovinazzo, Giuseppe; Marucci, Laura

    2010-05-01

    Purpose: To investigate the predictors of incidence and duration of xerostomia (XT) based on parotid glands (PG), submandibular glands (SMG), and both glands taken as a whole organ (TG) in head-and-neck cancer patients treated with intensity-modulated radiotherapy. Methods and Materials: A prospective study was initiated in May 2003. Sixty-three head-and-neck patients (44 with nasopharynx cancer) were included in the analysis. Using the dose-volume histogram the PG, SMG, and TG mean doses were calculated. Unstimulated and stimulated salivary flow were measured and XT-related questionnaires were compiled before and at 3, 6, 12, 18, and 24 months after radiotherapy. Salivary gland toxicity was evaluated using the Radiation Therapy Oncology Group scale, and Grade >=3 toxicity was used as the endpoint. The XT incidence was investigated according to descriptive statistics and univariate and multivariate analysis. The Bonferroni method was used for multiple comparison adjustment. Results: After a reduced flow at 3 months after radiotherapy, recovery of salivary flow was observed over time. Primary site and salivary gland mean doses and volumes were identified in univariate analysis as prognostic factors. Multivariate analysis confirmed that TG mean dose (p = 0.00066) and pretreatment stimulated salivary flow (p = 0.00420) are independent factors for predicting XT. Conclusion: The TG mean dose correlates with XT as assessed by Radiation Therapy Oncology Group criteria, salivary output, and XT-related questionnaires. Our results suggest that TG mean dose is a candidate dose constraint for reducing XT, requiring considerably more validation in non-nasopharyngeal cancer patients.

  5. Development of a Micro-Computed Tomography-Based Image-Guided Conformal Radiotherapy System for Small Animals

    SciTech Connect

    Zhou Hu; Rodriguez, Manuel; Haak, Fred van den; Nelson, Geoffrey; Jogani, Rahil

    2010-09-01

    Purpose: To report on the physical aspects of a system in which radiotherapy functionality was added to a micro-computed tomography (microCT) scanner, to evaluate the accuracy of this instrument, and to and demonstrate the application of this technology for irradiating tumors growing within the lungs of mice. Methods and Materials: A GE eXplore RS120 microCT scanner was modified by the addition of a two-dimensional subject translation stage and a variable aperture collimator. Quality assurance protocols for these devices, including measurement of translation stage positioning accuracy, collimator aperture accuracy, and collimator alignment with the X-ray beam, were devised. Use of this system for image-guided radiotherapy was assessed by irradiation of a solid water phantom as well as of two mice bearing spontaneous MYC-induced lung tumors. Radiation damage was assessed ex vivo by immunohistochemical detection of {gamma}H2AX foci. Results: The positioning error of the translation stage was found to be <0.05 mm, whereas after alignment of the collimator with the X-ray axis through adjustment of its displacement and rotation, the collimator aperture error was <0.1 mm measured at isocenter. Computed tomography image-guided treatment of a solid water phantom demonstrated target localization accuracy to within 0.1 mm. Gamma-H2AX foci were detected within irradiated lung tumors in mice, with contralateral lung tissue displaying background staining. Conclusions: Addition of radiotherapy functionality to a microCT scanner is an effective means of introducing image-guided radiation treatments into the preclinical setting. This approach has been shown to facilitate small-animal conformal radiotherapy while leveraging existing technology.

  6. Feasibility of dose escalation using intensity-modulated radiotherapy in posthysterectomy cervical carcinoma

    SciTech Connect

    D'Souza, Warren D. . E-mail: wdsou001@umaryland.edu; Ahamad, Anesa A.; Iyer, Revathy B.; Salehpour, Mohammad R.; Jhingran, Anuja; Eifel, Patricia J.

    2005-03-15

    Purpose: To evaluate retrospectively the utility of intensity-modulated radiotherapy (IMRT) in reducing the volume of normal tissues receiving radiation at varying dose levels when the female pelvis after hysterectomy is treated to doses of 50.4 Gy and 54 Gy. Methods and materials: Computed tomography scans from 10 patients who had previously undergone conventional postoperative RT were selected. The clinical tumor volume (vaginal apex and iliac nodes) and organs at risk were contoured. Margins were added to generate the planning tumor volume. The Pinnacle and Corvus planning systems were used to develop conventional and IMRT plans, respectively. Conventional four-field plans were prescribed to deliver 45 Gy (4F{sub 45Gy}) or 50.4 Gy; eight-field IMRT plans were prescribed to deliver 50.4 Gy (IMRT{sub 50.4Gy}) or 54 Gy (IMRT{sub 54Gy}) to the planning tumor volume. All plans were normalized so that {>=}97% of the planning tumor volume received the prescribed dose. Student's t test was used to compare the volumes of organs at risk receiving the same doses with different plans. Results: The mean volume of bowel receiving {>=}45 Gy was lower with the IMRT{sub 50.4Gy} (33% lower) and IMRT{sub 54Gy} (18% lower) plans than with the 4F{sub 45Gy} plan. The mean volume of rectum receiving {>=}45 Gy or {>=}50 Gy was also significantly reduced with the IMRT plans despite an escalation of the prescribed dose from 45 Gy with the conventional plans to 54 Gy with IMRT. The mean volume of bladder treated to 45 Gy was the same or slightly lower with the IMRT{sub 50.4Gy} and IMRT{sub 54Gy} plans compared with the 4F{sub 45Gy} plan. Compared with the 4F{sub 45Gy} plan, the IMRT{sub 50.4Gy} plan resulted in a smaller volume of bowel receiving 35-45 Gy and a larger volume of bowel receiving 50-55 Gy. Compared with the 4F{sub 45Gy} plan, the IMRT{sub 54Gy} plan resulted in smaller volumes of bowel receiving 45-50 Gy; however, small volumes of bowel received 55-60 Gy with the IMRT plan

  7. A Phase I Trial of Preoperative Partial Breast Radiotherapy: Patient Selection, Target Delineation, and Dose Delivery

    PubMed Central

    Blitzblau, Rachel C.; Arya, Ritu; Yoo, Sua; Baker, Jay A.; Chang, Zheng; Palta, Manisha; Duffy, Eileen; Horton, Janet K.

    2015-01-01

    Purpose Diffusion of accelerated partial breast irradiation (APBI) into clinical practice is limited by the need for specialized equipment and training. The accessible external beam technique yields unacceptable complication rates, likely due to large post-operative target volumes. We designed a phase I trial evaluating preoperative radiotherapy to the intact tumor utilizing widely available technology. Methods Patients received 15, 18, or 21Gy in a single fraction to the breast tumor plus margin. Magnetic resonance imaging (MRI) was used in conjunction with standard computed tomography (CT)-based planning to identify contrast enhancing tumor. Skin markers and an intra-tumor biopsy marker were utilized for verification during treatment. Results MRI imaging was critical for target delineation as not all breast tumors were reliably identified on CT scan. Breast shape differences were consistently seen between CT and MRI but did not impede image registration or tumor identification. Target volumes were markedly smaller than historical post-operative volumes and normal tissue constraints were easily met. A biopsy marker within the breast proved sufficient for set up localization. Conclusions This single fraction linear-accelerator based ABPI approach can be easily incorporated at most treatment centers. In vivo targeting may improve accuracy and can reduce the dose to normal tissues. PMID:25834942

  8. Incorporating system latency associated with real-time target tracking radiotherapy in the dose prediction step

    NASA Astrophysics Data System (ADS)

    Roland, Teboh; Mavroidis, Panayiotis; Shi, Chengyu; Papanikolaou, Nikos

    2010-05-01

    System latency introduces geometric errors in the course of real-time target tracking radiotherapy. This effect can be minimized, for example by the use of predictive filters, but cannot be completely avoided. In this work, we present a convolution technique that can incorporate the effect as part of the treatment planning process. The method can be applied independently or in conjunction with the predictive filters to compensate for residual latency effects. The implementation was performed on TrackBeam (Initia Ltd, Israel), a prototype real-time target tracking system assembled and evaluated at our Cancer Institute. For the experimental system settings examined, a Gaussian distribution attributable to the TrackBeam latency was derived with σ = 3.7 mm. The TrackBeam latency, expressed as an average response time, was deduced to be 172 ms. Phantom investigations were further performed to verify the convolution technique. In addition, patient studies involving 4DCT volumes of previously treated lung cancer patients were performed to incorporate the latency effect in the dose prediction step. This also enabled us to effectively quantify the dosimetric and radiobiological impact of the TrackBeam and other higher latency effects on the clinical outcome of a real-time target tracking delivery.

  9. Accuracy of dose planning for prostate radiotherapy in the presence of metallic implants evaluated by electron spin resonance dosimetry

    PubMed Central

    Alves, G.G.; Kinoshita, A.; de Oliveira, H.F.; Guimarães, F.S.; Amaral, L.L.; Baffa, O.

    2015-01-01

    Radiotherapy is one of the main approaches to cure prostate cancer, and its success depends on the accuracy of dose planning. A complicating factor is the presence of a metallic prosthesis in the femur and pelvis, which is becoming more common in elderly populations. The goal of this work was to perform dose measurements to check the accuracy of radiotherapy treatment planning under these complicated conditions. To accomplish this, a scale phantom of an adult pelvic region was used with alanine dosimeters inserted in the prostate region. This phantom was irradiated according to the planned treatment under the following three conditions: with two metallic prostheses in the region of the femur head, with only one prosthesis, and without any prostheses. The combined relative standard uncertainty of dose measurement by electron spin resonance (ESR)/alanine was 5.05%, whereas the combined relative standard uncertainty of the applied dose was 3.35%, resulting in a combined relative standard uncertainty of the whole process of 6.06%. The ESR dosimetry indicated that there was no difference (P>0.05, ANOVA) in dosage between the planned dose and treatments. The results are in the range of the planned dose, within the combined relative uncertainty, demonstrating that the treatment-planning system compensates for the effects caused by the presence of femur and hip metal prostheses. PMID:26017344

  10. Localized Low-Dose Radiotherapy for Follicular Lymphoma: History, Clinical Results, Mechanisms of Action, and Future Outlooks

    SciTech Connect

    Ganem, Gerard; Cartron, Guillaume; Girinsky, Theodore; Haas, Rick L.M.; Cosset, Jean Marc; Solal-Celigny, Philippe

    2010-11-15

    The extreme radiosensitivity of indolent lymphomas was reported in the early years of radiotherapy (RT). The efficacy of low-dose total body irradiation (1.5-2 Gy) was particularly demonstrative. Higher doses were considered appropriate for localized disease. The optimal (or conventional) dose of curative RT derived from the early studies was determined to be 30-35 Gy. Nevertheless, in older series addressing the tumoricidal radiation dose in non-Hodgkin's lymphomas, investigators noted that a significant number of 'nodular' lymphomas were controlled with a dose of <22 Gy for >3 years. The idea of reintroducing localized low-dose radiotherapy (LDRT) for indolent non-Hodgkin's lymphomas came from a clinical observation. The first study showing the high efficacy of LDRT (4 Gy in two fractions of 2 Gy within 3 days) in selected patients with chemoresistant, indolent, non-Hodgkin's lymphomas was published in 1994. Since this first report, at least eight series of patients treated with localized LDRT have been published, showing a 55% complete response rate in irradiated sites, with a median duration of 15-42 months. How LDRT induces lymphoma cell death remains partly unknown. However, some important advances have recently been reported. Localized LDRT induces an apoptosis of follicular lymphoma cells. This apoptotic cell death elicits an immune response mediated by macrophages and dendritic cells. Follicular lymphoma is probably an ideal model to explore these mechanisms. This review also discusses the future of LDRT for follicular lymphoma.

  11. Unified registration framework for cumulative dose assessment in cervical cancer across external beam radiotherapy and brachytherapy

    NASA Astrophysics Data System (ADS)

    Roy, Sharmili; Totman, John J.; Choo, Bok A.

    2016-03-01

    Dose accumulation across External Beam Radiotherapy (EBRT) and Brachytherapy (BT) treatment fractions in cervical cancer is extremely challenging due to structural dissimilarities and large inter-fractional anatomic deformations between the EBRT and BT images. The brachytherapy applicator and the bladder balloon, present only in the BT images, introduce missing structural correspondences for the underlying registration problem. Complex anatomical deformations caused by the applicator and the balloon, different rectum and bladder filling and tumor shrinkage compound the registration difficulties. Conventional free-form registration methods struggle to handle such topological differences. In this paper, we propose a registration pipeline that first transforms the original images to their distance maps based on segmentations of critical organs and then performs non-linear registration of the distance maps. The resulting dense deformation field is then used to transform the original anatomical image. The registration accuracy is evaluated on 27 image pairs from stage 2B-4A cervical cancer patients. The algorithm reaches a Hausdorff distance of close to 0:5 mm for the uterus, 2:2 mm for the bladder and 1:7 mm for the rectum when applied to (EBRT,BT) pairs, taken at time points more than three months apart. This generalized model-free framework can be used to register any combination of EBRT and BT images as opposed to methods in the literature that are tuned for either only (BT,BT) pair, or only (EBRT,EBRT) pair or only (BT,EBRT) pair. A unified framework for 3D dose accumulation across multiple EBRT and BT fractions is proposed to facilitate adaptive personalized radiation therapy.

  12. Dose calculation accuracy using cone-beam CT (CBCT) for pelvic adaptive radiotherapy

    NASA Astrophysics Data System (ADS)

    Guan, Huaiqun; Dong, Hang

    2009-10-01

    This study is to evaluate the dose calculation accuracy using Varian's cone-beam CT (CBCT) for pelvic adaptive radiotherapy. We first calibrated the Hounsfield Unit (HU) to electron density (ED) for CBCT using a mini CT QC phantom embedded into an IMRT QA phantom. We then used a Catphan 500 with an annulus around it to check the calibration. The combined CT QC and IMRT phantom provided correct HU calibration, but not Catphan with an annulus. For the latter, not only was the Teflon an incorrect substitute for bone, but the inserts were also too small to provide correct HUs for air and bone. For the former, three different scan ranges (6 cm, 12 cm and 20.8 cm) were used to investigate the HU dependence on the amount of scatter. To evaluate the dose calculation accuracy, CBCT and plan-CT for a pelvic phantom were acquired and registered. The single field plan, 3D conformal and IMRT plans were created on both CT sets. Without inhomogeneity correction, the two CT generated nearly the same plan. With inhomogeneity correction, the dosimetric difference between the two CT was mainly from the HU calibration difference. The dosimetric difference for 6 MV was found to be the largest for the single lateral field plan (maximum 6.7%), less for the 3D conformal plan (maximum 3.3%) and the least for the IMRT plan (maximum 2.5%). Differences for 18 MV were generally 1-2% less. For a single lateral field, calibration with 20.8 cm achieved the minimum dosimetric difference. For 3D and IMRT plans, calibration with a 12 cm range resulted in better accuracy. Because Catphan is the standard QA phantom for the on-board imager (OBI) device, we specifically recommend not using it for the HU calibration of CBCT.

  13. Prospective Study of Cone-Beam Computed Tomography Image-Guided Radiotherapy for Prone Accelerated Partial Breast Irradiation

    SciTech Connect

    Jozsef, Gabor; DeWyngaert, J. Keith; Becker, Stewart J.; Lymberis, Stella; Formenti, Silvia C.

    2011-10-01

    Purpose: To report setup variations during prone accelerated partial breast irradiation (APBI). Methods: New York University (NYU) 07-582 is an institutional review board-approved protocol of cone-beam computed tomography (CBCT) to deliver image-guided ABPI in the prone position. Eligible are postmenopausal women with pT1 breast cancer excised with negative margins and no nodal involvement. A total dose of 30 Gy in five daily fractions of 6 Gy are delivered to the planning target volume (the tumor cavity with 1.5-cm margin) by image-guided radiotherapy. Patients are set up prone, on a dedicated mattress, used for both simulation and treatment. After positioning with skin marks and lasers, CBCTs are performed and the images are registered to the planning CT. The resulting shifts (setup corrections) are recorded in the three principal directions and applied. Portal images are taken for verification. If they differ from the planning digital reconstructed radiographs, the patient is reset, and a new CBCT is taken. Results: 70 consecutive patients have undergone a total of 343 CBCTs: 7 patients had four of five planned CBCTs performed. Seven CBCTs (2%) required to be repeated because of misalignment in the comparison between portal and digital reconstructed radiograph image after the first CBCT. The mean shifts and standard deviations in the anterior-posterior (AP), superior-inferior (SI), and medial-lateral (ML) directions were -0.19 (0.54), -0.02 (0.33), and -0.02 (0.43) cm, respectively. The average root mean squares of the daily shifts were 0.50 (0.28), 0.29 (0.17), and 0.38 (0.20). A conservative margin formula resulted in a recommended margin of 1.26, 0.73, 0.96 cm in the AP, SI, and ML directions. Conclusion: CBCTs confirmed that the NYU prone APBI setup and treatment technique are reproducible, with interfraction variation comparable to those reported for supine setup. The currently applied margin (1.5 cm) adequately compensates for the setup variation detected.

  14. Image-guided radiotherapy using a mobile kilovoltage x-ray device

    SciTech Connect

    Sorensen, Stephen P. . E-mail: tsolberg@unmc.edu; Chow, Phillip E.; Kriminski, Sergey; Medin, Paul M.; Solberg, Timothy D.

    2006-04-01

    Abstract-: A mobile isocentric C-arm kilovoltage imager has been evaluated as a potential tool for image-guided radiotherapy. The C-arm is equipped with an amorphous silicon flat panel for high-quality image acquisition. Additionally, the device is capable of cone beam computed tomography (CT) and volumetric reconstruction. This is achieved through the application of a modified Feldkamp algorithm with acquisition over a 180 deg. scan arc. The number of projections can be varied from 100 to 1000, resulting in a reconstructed volume 20 cm in diameter by 15-cm long. While acquisition time depends upon number of projections, acceptable quality images can be obtained in less than 60 seconds. Image resolution and contrast of cone-beam phantom images have been compared with images from a conventional CT scanner. The system has a spatial resolution of {>=} 10 lp/cm and resolution is approximately equal in all 3 dimensions. Conversely, subject contrast is poorer than conventional CT, compromised by the increased scatter and underlying noise inherent in cone beam reconstruction, as well as the absence of filtering prior to reconstruction. The mobility of the C-arm makes it necessary to determine the C-arm position relative to the linear accelerator isocenter. Two solutions have been investigated: (1) the use of fiducial markers, embedded in the linac couch, that can subsequently be registered in the image sets; and (2), a navigation approach for infrared tracking of the C-arm relative to the linac isocenter. Observed accuracy in phantom positioning ranged from 1.0 to 1.5 mm using the navigation approach and 1.5 to 2.5 mm using the fiducial-based approach. As part of this work, the impact of respiratory motion on cone-beam image quality was evaluated, and a scheme for retrospective gating was devised. Results demonstrated that kilovoltage cone beam CT provides spatial integrity and resolution comparable to conventional CT. Cone-beam CT studies of patients undergoing

  15. Image-guided adaptive radiotherapy for prostate and head-and-neck cancers

    NASA Astrophysics Data System (ADS)

    O'Daniel, Jennifer C.

    In the current practice of radiation therapy, daily patient alignments have been based on external skin marks or on bone. However, internal organ variation (both motion and volumetric changes) between treatment fractions can displace the treatment target, causing target underdosage and normal tissue overdosage. In order to deliver the radiation treatment as planned, more accurate knowledge of the daily internal anatomy was needed. Additionally, treatments needed to adapt to these variations by either shifting the patient to account for the daily target position or by altering the treatment plan. In this dissertation, the question of whether inter-fractional variations in internal patient anatomy combined with external set-up uncertainties produced measurable differences between planned and delivered doses for prostate and head-and-neck cancer patients was investigated. Image-guided adaptive treatment strategies to improve tumor coverage and/or reduce normal tissue dose were examined. Treatment deliveries utilizing various alignment procedures for ten prostate cancer patients and eleven head-and-neck cancer patients, each of whom received multiple CT scans over the course of treatment, were simulated. The largest prostate dose losses between planning and delivery were correlated with anterior/posterior and superior/inferior prostate displacement. Daily bone alignment sufficiently maintained target coverage for 70% of patients, ultrasound for 90%, and CT for 100%. A no-action-level correction protocol, which corrected the daily bone alignment for the systematic internal displacement of the prostate based on a pre-determined number of CT image sets, successfully improved the prostate and seminal vesicle dosimetric coverage. Three CT image sets were sufficient to accurately correct the bone alignment scheme for the prostate internal systematic shifts. For head-and-neck cancer patient treatment, setup uncertainties and internal organ variations did not greatly affect

  16. SU-E-J-68: Adaptive Radiotherapy of Head and Neck Cancer: Re-Planning Based On Prior Dose

    SciTech Connect

    Dogan, N; Padgett, K; Evans, J; Sleeman, W; Song, S; Fatyga, M

    2015-06-15

    Purpose: Adaptive Radiotherapy (ART) with frequent CT imaging has been used to improve dosimetric accuracy by accounting for anatomical variations, such as primary tumor shrinkage and/or body weight loss, in Head and Neck (H&N) patients. In most ART strategies, the difference between the planned and the delivered dose is estimated by generating new plans on repeated CT scans using dose-volume constraints used with the initial planning CT without considering already delivered dose. The aim of this study was to assess the dosimetric gains achieved by re-planning based on prior dose by comparing them to re-planning not based-on prior dose for H&N patients. Methods: Ten locally-advanced H&N cancer patients were selected for this study. For each patient, six weekly CT imaging were acquired during the course of radiotherapy. PTVs, parotids, cord, brainstem, and esophagus were contoured on both planning and six weekly CT images. ART with weekly re-plans were done by two strategies: 1) Generating a new optimized IMRT plan without including prior dose from previous fractions (NoPriorDose) and 2) Generating a new optimized IMRT plan based on the prior dose given from previous fractions (PriorDose). Deformable image registration was used to accumulate the dose distributions between planning and six weekly CT scans. The differences in accumulated doses for both strategies were evaluated using the DVH constraints for all structures. Results: On average, the differences in accumulated doses for PTV1, PTV2 and PTV3 for NoPriorDose and PriorDose strategies were <2%. The differences in Dmean to the cord and brainstem were within 3%. The esophagus Dmean was reduced by 2% using PriorDose. PriorDose strategy, however, reduced the left parotid D50 and Dmean by 15% and 14% respectively. Conclusion: This study demonstrated significant parotid sparing, potentially reducing xerostomia, by using ART with IMRT optimization based on prior dose for weekly re-planning of H&N cancer patients.

  17. Palliative radiotherapy for advanced malignancies in a changing oncologic landscape: guiding principles and practice implementation.

    PubMed

    Jones, Joshua A; Simone, Charles B

    2014-07-01

    Radiotherapy can provide safe, cost-effective, efficient palliation of various symptoms of advanced cancer with minimal side effects. Radiotherapy can palliate pain related to bone metastases and growing visceral metastases or primary cancers, neurologic symptoms related to brain and spine metastases, other symptoms including cough and dyspnea from advanced cancers in the lung, bleeding from various internal and external tumors, and obstructive symptoms. Palliative radiotherapy should be offered in the context of a multidisciplinary oncology team including medical oncologists, palliative care clinicians and various surgical and interventional subspecialists. The prescription of radiotherapy should balance the convenience and fewer side effects associated with short, hypofractionated courses of radiotherapy with the potential greater durability associated with longer courses of radiotherapy in patients with more prolonged life expectancies. The judicious use of advanced techniques in radiotherapy, including intensity-modulated radiotherapy and stereotactic radiotherapy (SRT), may be warranted in select patients, and they can potentially improve symptom control and durability but are associated with increased technical and economic costs. PMID:25841695

  18. Radiotherapy for Head and Neck Cancer

    PubMed Central

    Yeh, Shyh-An

    2010-01-01

    Treatment for patients with head and neck cancer requires a multidisciplinary approach. Radiotherapy is employed as a primary treatment or as an adjuvant to surgery. Each specific subsite dictates the appropriate radiotherapy techniques, fields, dose, and fractionation scheme. Quality of life is also an important issue in the management of head and neck cancer. The radiation-related complications have a tremendous impact on the quality of life. Modern radiotherapy techniques, such as intensity-modulated radiotherapy and image-guided radiotherapy, can offer precise radiation delivery and reduce the dose to the surrounding normal tissues without compromise of target coverage. In the future, efforts should be made in the exploration of novel strategies to improve treatment outcome in patients with head and neck cancer. PMID:22550433

  19. Peripheral dose measurement in high-energy photon radiotherapy with the implementation of MOSFET

    PubMed Central

    Vlachopoulou, Vassiliki; Malatara, Georgia; Delis, Harry; Theodorou, Kiki; Kardamakis, Dimitrios; Panayiotakis, George

    2010-01-01

    AIM: To study the peripheral dose (PD) from high-energy photon beams in radiotherapy using the metal oxide semiconductor field effect transistor (MOSFET) dose verification system. METHODS: The radiation dose absorbed by the MOSFET detector was calculated taking into account the manufacturer’s Correction Factor, the Calibration Factor and the threshold voltage shift. PD measurements were carried out for three different field sizes (5 cm × 5 cm, 10 cm × 10 cm and 15 cm × 15 cm) and for various depths with the source to surface distance set at 100 cm. Dose measurements were realized on the central axis and then at distances (1 to 18 cm) parallel to the edge of the field, and were expressed as the percentage PD (% PD) with respect to the maximum dose (dmax). The accuracy of the results was evaluated with respect to a calibrated 0.3 cm3 ionization chamber. The reproducibility was expressed in terms of standard deviation (s) and coefficient of variation. RESULTS: % PD is higher near the phantom surface and drops to a minimum at the depth of dmax, and then tends to become constant with depth. Internal scatter radiation is the predominant source of PD and the depth dependence is determined by the attenuation of the primary photons. Closer to the field edge, where internal scatter from the phantom dominates, the % PD increases with depth because the ratio of the scatter to primary increases with depth. A few centimeters away from the field, where collimator scatter and leakage dominate, the % PD decreases with depth, due to attenuation by the water. The % PD decreases almost exponentially with the increase of distance from the field edge. The decrease of the % PD is more than 60% and can reach up to 90% as the measurement point departs from the edge of the field. For a given distance, the % PD is significantly higher for larger field sizes, due to the increase of the scattering volume. Finally, the measured PD obtained with MOSFET is higher than that obtained with an

  20. Motion prediction in MRI-guided radiotherapy based on interleaved orthogonal cine-MRI

    NASA Astrophysics Data System (ADS)

    Seregni, M.; Paganelli, C.; Lee, D.; Greer, P. B.; Baroni, G.; Keall, P. J.; Riboldi, M.

    2016-01-01

    In-room cine-MRI guidance can provide non-invasive target localization during radiotherapy treatment. However, in order to cope with finite imaging frequency and system latencies between target localization and dose delivery, tumour motion prediction is required. This work proposes a framework for motion prediction dedicated to cine-MRI guidance, aiming at quantifying the geometric uncertainties introduced by this process for both tumour tracking and beam gating. The tumour position, identified through scale invariant features detected in cine-MRI slices, is estimated at high-frequency (25 Hz) using three independent predictors, one for each anatomical coordinate. Linear extrapolation, auto-regressive and support vector machine algorithms are compared against systems that use no prediction or surrogate-based motion estimation. Geometric uncertainties are reported as a function of image acquisition period and system latency. Average results show that the tracking error RMS can be decreased down to a [0.2; 1.2] mm range, for acquisition periods between 250 and 750 ms and system latencies between 50 and 300 ms. Except for the linear extrapolator, tracking and gating prediction errors were, on average, lower than those measured for surrogate-based motion estimation. This finding suggests that cine-MRI guidance, combined with appropriate prediction algorithms, could relevantly decrease geometric uncertainties in motion compensated treatments.

  1. [Small animal image-guided radiotherapy: A new era for preclinical studies].

    PubMed

    Delpon, G; Frelin-Labalme, A-M; Heinrich, S; Beaudouin, V; Noblet, C; Begue, M; Le Deroff, C; Pouzoulet, F; Chiavassa, S

    2016-02-01

    Preclinical external beam radiotherapy irradiations used to be delivered with a static broad beam. To promote the transfer from animal to man, the preclinical treatment techniques dedicated to the animal have been optimized to be similar to those delivered to patients in clinical practice. In this context, preclinical irradiators have been developed. Due to the small sizes of the animals, and the irradiation beams, the scaling to the small animal dimensions involves specific problems. Reducing the size and energy of the irradiation beams require very high technical performance, especially for the mechanical stability of the irradiator and the spatial resolution of the imaging system. In addition, the determination of the reference absorbed dose rate must be conducted with a specific methodology and suitable detectors. To date, three systems are used for preclinical studies in France. The aim of this article is to present these new irradiators dedicated to small animals from a physicist point of view, including the commissioning and the quality control. PMID:26856635

  2. Stereotactic Body Radiotherapy for Oligometastasis: Opportunities for Biology to Guide Clinical Management.

    PubMed

    Correa, Rohann J M; Salama, Joseph K; Milano, Michael T; Palma, David A

    2016-01-01

    Oligometastasis refers to a state of limited metastatic disease burden, in which surgical or ablative treatment to all known visible metastases holds promise to extend survival or even effect cure. Stereotactic body radiotherapy is a form of radiation treatment capable of delivering a high biologically effective dose of radiation in a highly conformal manner, with a favorable toxicity profile. Enthusiasm for oligometastasis ablation, however, should be counterbalanced against the limited supporting evidence. It remains unknown to what extent (if any) ablation influences survival or quality of life. Rising clinical equipoise necessitates the completion of randomized controlled trials to assess this, several of which are underway. However, a lack of clear identification criteria or biomarkers to define the oligometastatic state hampers optimal patient selection.This narrative review explores the evolutionary origins of oligometastasis, the steps of the metastatic process at which oligometastases may arise, and the biomolecular mediators of this state. It discusses clinical outcomes with treatment of oligometastases, ongoing trials, and areas of basic and translational research that may lead to novel biomarkers. These efforts should provide a clearer, biomolecular definition of oligometastatic disease and aid in the accurate selection of patients for ablative therapies. PMID:27441744

  3. Radiation dose escalation by simultaneous modulated accelerated radiotherapy combined with chemotherapy for esophageal cancer: a phase II study

    PubMed Central

    Zhai, Tiantian; Chang, Daniel; Chen, Zhijian; Huang, Ruihong; Zhang, Wuzhe; Lin, Kun; Guo, Longjia; Zhou, Mingzhen; Li, Dongsheng; Li, Derui; Chen, Chuangzhen

    2016-01-01

    The outcomes for patients with esophageal cancer (EC) underwent standard-dose radical radiotherapy were still disappointing. This phase II study investigated the feasibility, safety and efficacy of radiation dose escalation using simultaneous modulated accelerated radiotherapy (SMART) combined with chemotherapy in 60 EC patients. Radiotherapy consisted of 66Gy at 2.2 Gy/fraction to the gross tumor and 54Gy at 1.8 Gy/fraction to subclinical diseases simultaneously. Chemotherapy including cisplatin and 5fluorouracil were administered to all patients during and after radiotherapy. The data showed that the majority of patients (98.3%) completed the whole course of radiotherapy and concurrent chemotherapy. The most common ≥ grade 3 acute toxicities were neutropenia (16.7%), followed by esophagitis (6.7%) and thrombopenia (5.0%). With a median follow-up of 24 months (5-38) for all patients and 30 months (18-38) for those still alive, 11 patients (18.3%) developed ≥ Grade 3 late toxicities and 2 (3.3%) of them died subsequently due to esophageal hemorrhage. The 1- and 2-year local-regional control, distant metastasis-free survival, disease-free survival and overall survival rates were 87.6% and 78.6%, 86.0% and 80.5%, 75.6% and 64.4%, 86.7% and 72.7%, respectively. SMART combined with concurrent chemotherapy is feasible in EC patients with tolerable acute toxicities. They showed a trend of significant improvements in local-regional control and overall survival. Further follow-up is needed to evaluate the late toxicities. PMID:26992206

  4. Improving anatomical mapping of complexly deformed anatomy for external beam radiotherapy and brachytherapy dose accumulation in cervical cancer

    SciTech Connect

    Vásquez Osorio, Eliana M. Kolkman-Deurloo, Inger-Karine K.; Schuring-Pereira, Monica; Zolnay, András; Heijmen, Ben J. M.; Hoogeman, Mischa S.

    2015-01-15

    Purpose: In the treatment of cervical cancer, large anatomical deformations, caused by, e.g., tumor shrinkage, bladder and rectum filling changes, organ sliding, and the presence of the brachytherapy (BT) applicator, prohibit the accumulation of external beam radiotherapy (EBRT) and BT dose distributions. This work proposes a structure-wise registration with vector field integration (SW+VF) to map the largely deformed anatomies between EBRT and BT, paving the way for 3D dose accumulation between EBRT and BT. Methods: T2w-MRIs acquired before EBRT and as a part of the MRI-guided BT procedure for 12 cervical cancer patients, along with the manual delineations of the bladder, cervix-uterus, and rectum-sigmoid, were used for this study. A rigid transformation was used to align the bony anatomy in the MRIs. The proposed SW+VF method starts by automatically segmenting features in the area surrounding the delineated organs. Then, each organ and feature pair is registered independently using a feature-based nonrigid registration algorithm developed in-house. Additionally, a background transformation is calculated to account for areas far from all organs and features. In order to obtain one transformation that can be used for dose accumulation, the organ-based, feature-based, and the background transformations are combined into one vector field using a weighted sum, where the contribution of each transformation can be directly controlled by its extent of influence (scope size). The optimal scope sizes for organ-based and feature-based transformations were found by an exhaustive analysis. The anatomical correctness of the mapping was independently validated by measuring the residual distances after transformation for delineated structures inside the cervix-uterus (inner anatomical correctness), and for anatomical landmarks outside the organs in the surrounding region (outer anatomical correctness). The results of the proposed method were compared with the results of the

  5. Clinical-dosimetric relationship between lacrimal gland dose and ocular toxicity after intensity-modulated radiotherapy for sinonasal tumours

    PubMed Central

    Batth, S S; Sreeraman, R; Dienes, E; Beckett, L A; Daly, M E; Cui, J; Mathai, M; Purdy, J A

    2013-01-01

    Objective: To characterise the relationship between lacrimal gland dose and ocular toxicity among patients treated by intensity-modulated radiotherapy (IMRT) for sinonasal tumours. Methods: 40 patients with cancers involving the nasal cavity and paranasal sinuses were treated with IMRT to a median dose of 66.0 Gy. Toxicity was scored using the Radiation Therapy Oncology Group morbidity criteria based on conjunctivitis, corneal ulceration and keratitis. The paired lacrimal glands were contoured as organs at risk, and the mean dose, maximum dose, V10, V20 and V30 were determined. Statistical analysis was performed using logistic regression and the Akaike information criterion (AIC). Results: The maximum and mean dose to the ipsilateral lacrimal gland were 19.2 Gy (range, 1.4–75.4 Gy) and 14.5 Gy (range, 11.1–67.8 Gy), respectively. The mean V10, V20 and V30 values were 50%, 25% and 17%, respectively. The incidence of acute and late Grade 3+ toxicities was 23% and 19%, respectively. Based on logistic regression and AIC, the maximum dose to the ipsilateral lacrimal gland was identified as a more significant predictor of acute toxicity (AIC, 53.89) and late toxicity (AIC, 32.94) than the mean dose (AIC, 56.13 and 33.83, respectively). The V20 was identified as the most significant predictor of late toxicity (AIC, 26.81). Conclusion: A dose–response relationship between maximum dose to the lacrimal gland and ocular toxicity was established. Our data suggesting a threshold relationship may be useful in establishing dosimetric guidelines for IMRT planning that may decrease the risk of acute and late lacrimal toxicities in the future. Advances in knowledge: A threshold relationship between radiation dose to the lacrimal gland and ocular toxicity was demonstrated, which may aid in treatment planning and reducing the morbidity of radiotherapy for sinonasal tumours. PMID:24167183

  6. Analysis of Dose at the Site of Second Tumor Formation After Radiotherapy to the Central Nervous System

    SciTech Connect

    Galloway, Thomas J.; Indelicato, Daniel J.; Amdur, Robert J.; Morris, Christopher G.; Swanson, Erika L.; Marcus, Robert B.

    2012-01-01

    Purpose: Second tumors are an uncommon complication of multimodality treatment of childhood cancer. The present analysis attempted to correlate the dose received as a component of primary treatment and the site of the eventual development of a second tumor. Methods and Materials: We retrospectively identified 16 patients who had received radiotherapy to sites in the craniospinal axis and subsequently developed a second tumor. We compared the historical fields and port films of the primary treatment with the modern imaging of the second tumor locations. We classified the location of the second tumors as follows: in the boost field; marginal to the boost field, but in a whole-brain field; in a whole-brain field; marginal to the whole brain/primary treatment field; and distant to the field. We divided the dose received into 3 broad categories: high dose (>45 Gy), moderate dose (20-36 Gy), and low dose (<20 Gy). Results: The most common location of the second tumor was in the whole brain field (57%) and in the moderate-dose range (81%). Conclusions: Our data contradict previous publications that suggested that most second tumors develop in tissues that receive a low radiation dose. Almost all the second tumors in our series occurred in tissue within a target volume in the cranium that had received a moderate dose (20-36 Gy). These findings suggest that a major decrease in the brain volume that receives a moderate radiation dose is the only way to substantially decrease the second tumor rate after central nervous system radiotherapy.

  7. Dose verification in carcinoma of uterine cervix patients undergoing 3D conformal radiotherapy with Farmer type ion chamber

    PubMed Central

    Srinivas, Challapalli; Kumar, P Suman; Ravichandran, Ramamoorthy; Banerjee, S; Saxena, P.U; Kumar, E.S Arun; Pai, Dinesh K.

    2014-01-01

    External beam radiotherapy (EBRT) for carcinoma of uterine cervix is a basic line of treatment with three dimensional conformal radiotherapy (3DCRT) in large number of patients. There is need for an established method for verification dosimetry. We tried to document absorbed doses in a group of carcinoma cervix patients by inserting a 0.6 cc Farmer type ion chamber in the vaginal cavity. A special long perspex sleeve cap is designed to cover the chamber for using in the patient's body. Response of ionization chamber is checked earlier in water phantom with and without cap. Treatment planning was carried out with X-ray computed tomography (CT) scan and with the chamber along with cap in inserted position, and with the images Xio treatment planning system. Three measurements on 3 days at 5-6 fraction intervals were recorded in 12 patients. Electrometer measured charges are converted to absorbed dose at the chamber center, in vivo. Our results show good agreement with planned dose within 3% against prescribed dose. This study, is a refinement over our previous studies with transmission dosimetry and chemicals in ampules. This preliminary work shows promise that this can be followed as a routine dose check with special relevance to new protocols in the treatment of carcinoma cervix with EBRT. PMID:25525313

  8. On the significance of density-induced speed of sound variations on US-guided radiotherapy

    SciTech Connect

    Fontanarosa, Davide; Meer, Skadi van der; Verhaegen, Frank

    2012-10-15

    Purpose: To show the effect of speed of sound (SOS) aberration on ultrasound guided radiotherapy (US-gRT) as a function of implemented workflow. US systems assume that SOS is constant in human soft tissues (at a value of 1540 m/s), while its actual nonuniform distribution produces small but systematic errors of up to a few millimeters in the positions of scanned structures. When a coregistered computerized tomography (CT) scan is available, the US image can be corrected for SOS aberration. Typically, image guided radiotherapy workflows implementing US systems only provide a CT scan at the simulation (SIM) stage. If changes occur in geometry or density distribution between SIM and treatment (TX) stage, SOS aberration can change accordingly, with a final impact on the measured position of structures which is dependent on the workflow adopted. Methods: Four basic scenarios were considered of possible changes between SIM and TX: (1) No changes, (2) only patient position changes (rigid rotation-translation), (3) only US transducer position changes (constrained on patient's surface), and (4) patient tissues thickness changes. Different SOS aberrations may arise from the different scenarios, according to the specific US-gRT workflow used: intermodality (INTER) where TX US scans are compared to SIM CT scans; intramodality (INTRA) where TX US scans are compared to SIM US scans; and INTERc and INTRAc where all US images are corrected for SOS aberration (using density information provided by SIM CT). For an experimental proof of principle, the effect of tissues thickness change was simulated in the different workflows: a dual layered phantom was filled with layers of sunflower oil (SOS 1478 m/s), water (SOS 1482 m/s), and 20% saline solution (SOS 1700 m/s). The phantom was US scanned, the layer thicknesses were increased and the US scans were repeated. The errors resulting from the different workflows were compared. Results: Theoretical considerations show that workflows

  9. Full-dose capecitabine with local radiotherapy: one of the treatment options for inoperable T4 breast cancer.

    PubMed

    Hirowatari, Hisako; Karasawa, Kumiko; Izawa, Hiromi; Ito, Kana; Sasai, Keisuke; Furuya, Tomohisa; Ozawa, Shuichi; Arakawa, Atsushi; Orihata, Gotaro; Saito, Mitsue

    2011-04-01

    A 48-year-old woman presented with a 15-cm diameter tumor in her left breast with fixation to the chest wall and palpable axillary lymph nodes. Pathology study showed pure-type mucinous carcinoma. Pretreatment staging investigations showed multiple lung metastases, which resulted in the diagnosis of T4N2M1 breast cancer. Four cycles of cyclophosphamide 700 mg/m(2)/epirubicin 70 mg/m(2) (CE) were performed initially, but the tumors decreased only within the treatment response criteria of stable disease (SD). The second regimen of docetaxel could not continue due to drug allergy. Two more cycles of CE did not improve the situation. Then, treatment was continued with full-dose capecitabine with local radiotherapy. She received radiotherapy to the left breast and axillary region with 60 Gy/30 fractions/6 weeks and concomitant capecitabine 2400 mg/body twice daily for 21 days; the cycles were repeated every 28 days. After radiotherapy, tumors decreased in size, and the skin ulceration disappeared. She continued to receive capecitabine on the same schedule. She now has no palpable tumor in her left breast and no tumor in the axilla or lung on CT. She is alive and well 6 years after radiotherapy. PMID:21519998

  10. Toward efficient biomechanical-based deformable image registration of lungs for image-guided radiotherapy

    NASA Astrophysics Data System (ADS)

    Al-Mayah, Adil; Moseley, Joanne; Velec, Mike; Brock, Kristy

    2011-08-01

    Both accuracy and efficiency are critical for the implementation of biomechanical model-based deformable registration in clinical practice. The focus of this investigation is to evaluate the potential of improving the efficiency of the deformable image registration of the human lungs without loss of accuracy. Three-dimensional finite element models have been developed using image data of 14 lung cancer patients. Each model consists of two lungs, tumor and external body. Sliding of the lungs inside the chest cavity is modeled using a frictionless surface-based contact model. The effect of the type of element, finite deformation and elasticity on the accuracy and computing time is investigated. Linear and quadrilateral tetrahedral elements are used with linear and nonlinear geometric analysis. Two types of material properties are applied namely: elastic and hyperelastic. The accuracy of each of the four models is examined using a number of anatomical landmarks representing the vessels bifurcation points distributed across the lungs. The registration error is not significantly affected by the element type or linearity of analysis, with an average vector error of around 2.8 mm. The displacement differences between linear and nonlinear analysis methods are calculated for all lungs nodes and a maximum value of 3.6 mm is found in one of the nodes near the entrance of the bronchial tree into the lungs. The 95 percentile of displacement difference ranges between 0.4 and 0.8 mm. However, the time required for the analysis is reduced from 95 min in the quadratic elements nonlinear geometry model to 3.4 min in the linear element linear geometry model. Therefore using linear tetrahedral elements with linear elastic materials and linear geometry is preferable for modeling the breathing motion of lungs for image-guided radiotherapy applications.

  11. Markerless tumor tracking using short kilovoltage imaging arcs for lung image-guided radiotherapy

    NASA Astrophysics Data System (ADS)

    Shieh, Chun-Chien; Keall, Paul J.; Kuncic, Zdenka; Huang, Chen-Yu; Feain, Ilana

    2015-12-01

    The ability to monitor tumor motion without implanted markers is clinically advantageous for lung image-guided radiotherapy (IGRT). Existing markerless tracking methods often suffer from overlapping structures and low visibility of tumors on kV projection images. We introduce the short arc tumor tracking (SATT) method to overcome these issues. The proposed method utilizes multiple kV projection images selected from a nine-degree imaging arc to improve tumor localization, and respiratory-correlated 4D cone-beam CT (CBCT) prior knowledge to minimize the effects of overlapping anatomies. The 3D tumor position is solved as an optimization problem with prior knowledge incorporated via regularization. We retrospectively validated SATT on 11 clinical scans from four patients with central tumors. These patients represent challenging scenarios for markerless tumor tracking due to the inferior adjacent contrast. The 3D trajectories of implanted fiducial markers were used as the ground truth for tracking accuracy evaluation. In all cases, the tumors were successfully tracked at all gantry angles. Compared to standard pre-treatment CBCT guidance alone, trajectory errors were significantly smaller with tracking in all cases, and the improvements were the most prominent in the superior-inferior direction. The mean 3D tracking error ranged from 2.2-9.9 mm, which was 0.4-2.6 mm smaller compared to pre-treatment CBCT. In conclusion, we were able to directly track tumors with inferior visibility on kV projection images using SATT. Tumor localization accuracies are significantly better with tracking compared to the current standard of care of lung IGRT. Future work involves the prospective evaluation and clinical implementation of SATT.

  12. Role of Intra- or Periprostatic Calcifications in Image-Guided Radiotherapy for Prostate Cancer

    SciTech Connect

    Hanna, Samir Abdallah; Neves-Junior, Wellington Furtado Pimenta; Marta, Gustavo Nader; Haddad, Cecilia Maria Kalil; Fernandes da Silva, Joao Luis

    2012-03-01

    Purpose: Image-guided radiotherapy (IGRT) allows more precise localization of the prostate, thus minimizing errors resulting from organ motion and set-up during treatment of prostate cancer. Using megavoltage cone-beam computed tomography (MVCBCT), references such as bones, the prostate itself or implanted fiducial markers can be used as surrogates to correct patient positioning immediately before each treatment fraction. However, the use of fiducials requires an invasive procedure and may increase costs. We aimed to assess whether intra- or periprostatic calcifications (IPC) could be used as natural fiducials. Methods and Materials: Data on patients treated with IGRT for prostate cancer with clearly visible IPC and implanted fiducials in both planning CT and MVCBCT images were reviewed. IPC were classified as central when inside the prostate and peripheral when within the planning target volume. Daily deviations in lateral, longitudinal, and vertical directions from baseline positioning using fiducials and using IPC were compared. Results: A total of 287 MVCBCT images were obtained and analyzed from 10 patients. The mean {+-} standard deviation daily deviation (mm) in the lateral, longitudinal, and vertical coordinates were 0.55 {+-} 3.11, 0.58 {+-} 3.45, and -0.54 {+-} 4.03, respectively, for fiducials, and 0.72 {+-} 3.22, 0.63 {+-} 3.58, and -0.69 {+-} 4.26, for IPC. The p values for comparisons (fiducials vs. IPC) were 0.003, 0.653, and 0.078 for lateral, longitudinal, and vertical coordinates, respectively. When cases with central IPC were analyzed (n = 7), no significant difference was found in such comparisons. Central IPC and fiducials exhibited a similar pattern of displacement during treatment, with equal values for daily displacements in the three directions for more than 90% of measurements. Conclusions: Our data suggest that centrally located IPC may be used as natural fiducials for treatment positioning during IGRT for prostate cancer, with potential

  13. Multi-System Verification of Registrations for Image-Guided Radiotherapy in Clinical Trials

    SciTech Connect

    Cui Yunfeng; Galvin, James M.; Straube, William L.; Bosch, Walter R.; Purdy, James A.; Li, X. Allen; Xiao Ying

    2011-09-01

    Purpose: To provide quantitative information on the image registration differences from multiple systems for image-guided radiotherapy (IGRT) credentialing and margin reduction in clinical trials. Methods and Materials: Images and IGRT shift results from three different treatment systems (Tomotherapy Hi-Art, Elekta Synergy, Varian Trilogy) have been sent from various institutions to the Image-Guided Therapy QA Center (ITC) for evaluation for the Radiation Therapy Oncology Group (RTOG) trials. Nine patient datasets (five head-and-neck and four prostate) were included in the comparison, with each patient having 1-4 daily individual IGRT studies. In all cases, daily shifts were re-calculated by re-registration of the planning CT with the daily IGRT data using three independent software systems (MIMvista, FocalSim, VelocityAI). Automatic fusion was used in all calculations. The results were compared with those submitted from institutions. Similar regions of interest (ROIs) and same initial positions were used in registrations for inter-system comparison. Different slice spacings for CBCT sampling and different ROIs for registration were used in some cases to observe the variation of registration due to these factors. Results: For the 54 comparisons with head-and-neck datasets, the absolute values of differences of the registration results between different systems were 2.6 {+-} 2.1 mm (mean {+-} SD; range 0.1-8.6 mm, left-right [LR]), 1.7 {+-} 1.3 mm (0.0-4.9 mm, superior-inferior [SI]), and 1.8 {+-} 1.1 mm (0.1-4.0 mm, anterior-posterior [AP]). For the 66 comparisons in prostate cases, the differences were 1.1 {+-} 1.0 mm (0.0-4.6 mm, LR), 2.1 {+-} 1.7 mm (0.0-6.6 mm, SI), and 2.0 {+-} 1.8 mm (0.1-6.9 mm, AP). The differences caused by the slice spacing variation were relatively small, and the different ROI selections in FocalSim and MIMvista also had limited impact. Conclusion: The extent of differences was reported when different systems were used for image

  14. Image-Guided Radiotherapy Using a Modified Industrial Micro-CT for Preclinical Applications

    PubMed Central

    Felix, Manuela C.; Fleckenstein, Jens; Kirschner, Stefanie; Hartmann, Linda; Wenz, Frederik; Brockmann, Marc A.

    2015-01-01

    Purpose/Objective Although radiotherapy is a key component of cancer treatment, its implementation into pre-clinical in vivo models with relatively smal