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Sample records for guided multibeam radiotherapy

  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. The choice of multi-beam IMRT for whole breast radiotherapy in early-stage right breast cancer.

    PubMed

    Haciislamoglu, Emel; Colak, Fatma; Canyilmaz, Emine; Zengin, Ahmet Yasar; Yilmaz, Ahmet Hakan; Yoney, Adnan; Bahat, Zumrut

    2016-01-01

    The aim of this study was to identify a rational strategy for the selection of multi-beam IMRT in patients with right breast cancer through the comparison of dosimetric parameters of the planning target volume (PTV) and organs at risk (OARs) using five different radiotherapy modalities. This was a retrospective study using computed tomography scans from ten patients with early-stage right breast cancer who had been treated previously. Three dimensional conformal radiotherapy (3DCRT), forward-planned IMRT (for-IMRT), inverse-planned IMRT (inv-IMRT), helical tomotherapy (HT), and volumetric-modulated arc therapy (VMAT) were planned for each patient. The plans were compared according to dose-volume histogram analysis. The most significant impact of inverse-planned multi-beam modalities for right breast cancer was the reduction of Dmax, Dmean, V53.5 and prescribed dose volume (cc) outside of the PTV (breast) (OB-V50) of the PTV. HT decreased the ipsilateral OAR volumes receiving higher doses. In exchange, HT also increased the volumes receiving low doses, which is known to lead to an increased rate of radiation-induced secondary malignancies. The heart, LAD, and contralateral doses for 3DCRT and for-IMRT were significantly lower than those for inv-IMRT, HT, and VMAT. In addition, inv-IMRT demonstrated an increase in exposed volume of heart, LAD, ipsilateral lung, and contralateral lung compared with those parameters for HT or VMAT. Although it is known to reduce cardiac toxicity with breath hold technique in left sided breast cancer, similarly it is possible for 3DCRT and for-IMRT techniques in right sided breast cancer even in free breathing. PMID:27350922

  3. 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

  4. 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

  5. [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

  6. Multibeam inverse intensity-modulated radiotherapy (IMRT) for whole breast irradiation: a single center experience in China

    PubMed Central

    Ma, Jinli; Mei, Xin; Chen, Jiayi; Yu, Xiaoli; Guo, Xiaomao

    2015-01-01

    Purpose To present the clinical experience in our cancer center with multibeam inverse intensity-modulated radiotherapy (IMRT) for early stage breast cancer (BC) patients with whole breast irradiation (WBI). Methods We retrospectively analyzed 622 patients with Stage 0 to III BC treated from 2008 to 2011 with wide local excision and WBI, using an inverse IMRT technique. All of the patients were prescribed a total dose of 50 Gy to the whole breast in 2-Gy fractions, followed by a tumor bed boost of 10 Gy in 5 fractions using an electron beam. Results Of all of the patients, 132 (21.2%) received whole breast plus regional lymph node (RLN) irradiation. 438 of 622 patients had records of acute skin toxicity based on common terminology criteria (CTC) for adverse events. Two hundred eighty (64%) patients had Grade 0/1 toxicity, 153 (35%) had Grade 2 and only 4 patients experienced grade 3 toxicity. Seventy patients (16%) had moist desquamation. Univariate analysis revealed that breast planning target volume was the only predictive factor for Grade ≥2 acute dermatitis (P = 0.002). After 4 years, 170 patients reported cosmetic results by self-assessment, of whom 151 (89%) patients reported good/excellent cosmetic results, and 17 (11%) patients reported fair assessments. For invasive cancer, the four-year rate of freedom from locoregional recurrence survival was 98.3%. Regarding carcinoma in situ, no patients experienced recurrence. Conclusion BC patients who underwent conservative surgery followed by inverse IMRT plan exhibited acceptable acute toxicities and clinical outcomes. Longer follow-up is needed. PMID:26393681

  7. Whole breast radiotherapy in prone and supine position: is there a place for multi-beam IMRT?

    PubMed Central

    2013-01-01

    Background Early stage breast cancer patients are long-term survivors and finding techniques that may lower acute and late radiotherapy-induced toxicity is crucial. We compared dosimetry of wedged tangential fields (W-TF), tangential field intensity-modulated radiotherapy (TF-IMRT) and multi-beam IMRT (MB-IMRT) in prone and supine positions for whole-breast irradiation (WBI). Methods MB-IMRT, TF-IMRT and W-TF treatment plans in prone and supine positions were generated for 18 unselected breast cancer patients. The median prescription dose to the optimized planning target volume (PTVoptim) was 50 Gy in 25 fractions. Dose-volume parameters and indices of conformity were calculated for the PTVoptim and organs-at-risk. Results Prone MB-IMRT achieved (p<0.01) the best dose homogeneity compared to WTF in the prone position and WTF and MB-IMRT in the supine position. Prone IMRT scored better for all dose indices. MB-IMRT lowered lung and heart dose (p<0.05) in supine position, however the lowest ipsilateral lung doses (p<0.001) were in prone position. In left-sided breast cancer patients population averages for heart sparing by radiation dose was better in prone position; though non-significant. For patients with a PTVoptim volume ≥600 cc heart dose was consistently lower in prone position; while for patients with smaller breasts heart dose metrics were comparable or worse compared to supine MB-IMRT. Doses to the contralateral breast were similar regardless of position or technique. Dosimetry of prone MB-IMRT and prone TF-IMRT differed slightly. Conclusions MB-IMRT is the treatment of choice in supine position. Prone IMRT is superior to any supine treatment for right-sided breast cancer patients and left-sided breast cancer patients with larger breasts by obtaining better conformity indices, target dose distribution and sparing of the organs-at-risk. The influence of treatment techniques in prone position is less pronounced; moreover dosimetric differences between TF

  8. Dosimetry characterization of a multibeam radiotherapy treatment for age-related macular degeneration

    SciTech Connect

    Lee, Choonsik; Chell, Erik; Gertner, Michael; Hansen, Steven; Howell, Roger W.; Hanlon, Justin; Bolch, Wesley E.

    2008-11-15

    Age-related macular degeneration (ARMD) is a major health problem worldwide. Advanced ARMD, which ultimately leads to profound vision loss, has dry and wet forms, which account for 20% and 80% of cases involving severe vision loss, respectively. A new device and approach for radiation treatment of ARMD has been recently developed by Oraya Therapeutics, Inc. (Newark, CA). The goal of the present study is to provide a initial dosimetry characterization of the proposed radiotherapy treatment via Monte Carlo radiation transport simulation. A 3D eye model including cornea, anterior chamber, lens, orbit, fat, sclera, choroid, retina, vitreous, macula, and optic nerve was carefully designed. The eye model was imported into the MCNPX2.5 Monte Carlo code and radiation transport simulations were undertaken to obtain absorbed doses and dose volume histograms (DVH) to targeted and nontargeted structures within the eye. Three different studies were undertaken to investigate (1) available beam angles that maximized the dose to the macula target tissue, simultaneously minimizing dose to normal tissues, (2) the energy dependency of the DVH for different x-ray energies (80, 100, and 120 kVp), and (3) the optimal focal spot size among options of 0.0, 0.4, 1.0, and 5.5 mm. All results were scaled to give 8 Gy to the macula volume, which is the current treatment requirement. Eight beam treatment angles are currently under investigation. In all eight beam angles, the source-to-target distance is 13 cm, and the polar angle of entry is 30 degree sign from the geometric axis of the eye. The azimuthal angle changes in eight increments of 45 degree sign in a clockwise fashion, such that an azimuthal angle of 0 degree sign corresponds to the 12 o'clock position when viewing the treated eye. Based on considerations of nontarget tissue avoidance, as well as facial-anatomical restrictions on beam delivery, treatment azimuthal angles between 135 degree sign and 225 degree sign would be available

  9. 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

  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. 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

  12. 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

  13. 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.

  14. 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.

  15. 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

  16. 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.

  17. 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.

  18. 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

  19. 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

  20. Multibeam klystron

    NASA Technical Reports Server (NTRS)

    Vancil, Bernard K. (Inventor); Wintucky, Edwin G. (Inventor)

    2006-01-01

    A multibeam, electrostatically focused klystron includes a plurality of conductive members, ones of which are recessed to provide input and output sections of microwave cavities, wherein focusing voltage is applied between those sections. The conductive members are either spaced along the path of multiple beams, or stacked in insulated relation, in either case being supported by glass rods within a glass envelope.

  1. 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

  2. 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

  3. 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

  4. 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

  5. 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.

  6. 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

  7. 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.

  8. 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.

  9. 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.

  10. 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

  11. 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

  12. 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.

  13. 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

  14. 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

  15. 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

  16. 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.

  17. 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

  18. 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

  19. 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.

  20. 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

  1. 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.

  2. 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.

  3. 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.

  4. 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

  5. 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.

  6. 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.

  7. 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.

  8. 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

  9. 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

  10. 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

  11. 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

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  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. 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

  20. 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

  1. 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

  2. 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

  3. 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

  4. 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

  5. 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

  6. 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.

  7. 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.

  8. 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

  9. 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.

  10. 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.

  11. 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.

  12. 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

  13. 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

  14. 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.

  15. 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

  16. 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

  17. Development of an ultrasmall C-band linear accelerator guide for a four-dimensional image-guided radiotherapy system with a gimbaled x-ray head.

    PubMed

    Kamino, Yuichiro; Miura, Sadao; Kokubo, Masaki; Yamashita, Ichiro; Hirai, Etsuro; Hiraoka, Masahiro; Ishikawa, Junzo

    2007-05-01

    We are developing a four-dimensional image-guided radiotherapy system with a gimbaled x-ray head. It is capable of pursuing irradiation and delivering irradiation precisely with the help of an agile moving x-ray head on the gimbals. Requirements for the accelerator guide were established, system design was developed, and detailed design was conducted. An accelerator guide was manufactured and basic beam performance and leakage radiation from the accelerator guide were evaluated at a low pulse repetition rate. The accelerator guide including the electron gun is 38 cm long and weighs about 10 kg. The length of the accelerating structure is 24.4 cm. The accelerating structure is a standing wave type and is composed of the axial-coupled injector section and the side-coupled acceleration cavity section. The injector section is composed of one prebuncher cavity, one buncher cavity, one side-coupled half cavity, and two axial coupling cavities. The acceleration cavity section is composed of eight side-coupled nose reentrant cavities and eight coupling cavities. The electron gun is a diode-type gun with a cerium hexaboride (CeB6) direct heating cathode. The accelerator guide can be operated without any magnetic focusing device. Output beam current was 75 mA with a transmission efficiency of 58%, and the average energy was 5.24 MeV. Beam energy was distributed from 4.95 to 5.6 MeV. The beam profile, measured 88 mm from the beam output hole on the axis of the accelerator guide, was 0.7 mm X 0.9 mm full width at half maximum (FWHM) width. The beam loading line was 5.925 (MeV)-Ib (mA) X 0.00808 (MeV/mA), where Ib is output beam current. The maximum radiation leakage of the accelerator guide at 100 cm from the axis of the accelerator guide was calculated as 0.33 cGy/min at the rated x-ray output of 500 cGy/min from the measured value. This leakage requires no radiation shielding for the accelerator guide itself per IEC 60601-2-1. PMID:17555261

  18. Development of an ultrasmall C-band linear accelerator guide for a four-dimensional image-guided radiotherapy system with a gimbaled x-ray head

    SciTech Connect

    Kamino, Yuichiro; Miura, Sadao; Kokubo, Masaki; Yamashita, Ichiro; Hirai, Etsuro; Hiraoka, Masahiro; Ishikawa, Junzo

    2007-05-15

    We are developing a four-dimensional image-guided radiotherapy system with a gimbaled x-ray head. It is capable of pursuing irradiation and delivering irradiation precisely with the help of an agile moving x-ray head on the gimbals. Requirements for the accelerator guide were established, system design was developed, and detailed design was conducted. An accelerator guide was manufactured and basic beam performance and leakage radiation from the accelerator guide were evaluated at a low pulse repetition rate. The accelerator guide including the electron gun is 38 cm long and weighs about 10 kg. The length of the accelerating structure is 24.4 cm. The accelerating structure is a standing wave type and is composed of the axial-coupled injector section and the side-coupled acceleration cavity section. The injector section is composed of one prebuncher cavity, one buncher cavity, one side-coupled half cavity, and two axial coupling cavities. The acceleration cavity section is composed of eight side-coupled nose reentrant cavities and eight coupling cavities. The electron gun is a diode-type gun with a cerium hexaboride (CeB{sub 6}) direct heating cathode. The accelerator guide can be operated without any magnetic focusing device. Output beam current was 75 mA with a transmission efficiency of 58%, and the average energy was 5.24 MeV. Beam energy was distributed from 4.95 to 5.6 MeV. The beam profile, measured 88 mm from the beam output hole on the axis of the accelerator guide, was 0.7 mmx0.9 mm full width at half maximum (FWHM) width. The beam loading line was 5.925 (MeV)-I{sub b} (mA)x0.00808 (MeV/mA), where I{sub b} is output beam current. The maximum radiation leakage of the accelerator guide at 100 cm from the axis of the accelerator guide was calculated as 0.33 cGy/min at the rated x-ray output of 500 cGy/min from the measured value. This leakage requires no radiation shielding for the accelerator guide itself per IEC 60601-2-1.

  19. 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.

  20. 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

  1. Evaluation of image guided motion management methods in lung cancer radiotherapy

    SciTech Connect

    Zhuang, Ling; Yan, Di; Liang, Jian; Ionascu, Dan; Mangona, Victor; Yang, Kai; Zhou, Jun

    2014-03-15

    Purpose: To evaluate the accuracy and reliability of three target localization methods for image guided motion management in lung cancer radiotherapy. Methods: Three online image localization methods, including (1) 2D method based on 2D cone beam (CB) projection images, (2) 3D method using 3D cone beam CT (CBCT) imaging, and (3) 4D method using 4D CBCT imaging, have been evaluated using a moving phantom controlled by (a) 1D theoretical breathing motion curves and (b) 3D target motion patterns obtained from daily treatment of 3 lung cancer patients. While all methods are able to provide target mean position (MP), the 2D and 4D methods can also provide target motion standard deviation (SD) and excursion (EX). For each method, the detected MP/SD/EX values are compared to the analytically calculated actual values to calculate the errors. The MP errors are compared among three methods and the SD/EX errors are compared between the 2D and 4D methods. In the theoretical motion study (a), the dependency of MP/SD/EX error on EX is investigated with EX varying from 2.0 cm to 3.0 cm with an increment step of 0.2 cm. In the patient motion study (b), the dependency of MP error on target sizes (2.0 cm and 3.0 cm), motion patterns (four motions per patient) and EX variations is investigated using multivariant linear regression analysis. Results: In the theoretical motion study (a), the MP detection errors are −0.2 ± 0.2, −1.5 ± 1.1, and −0.2 ± 0.2 mm for 2D, 3D, and 4D methods, respectively. Both the 2D and 4D methods could accurately detect motion pattern EX (error < 1.2 mm) and SD (error < 1.0 mm). In the patient motion study (b), MP detection error vector (mm) with the 2D method (0.7 ± 0.4) is found to be significantly less than with the 3D method (1.7 ± 0.8,p < 0.001) and the 4D method (1.4 ± 1.0, p < 0.001) using paired t-test. However, no significant difference is found between the 4D method and the 3D method. Based on multivariant linear regression analysis, the

  2. Image-guided stereotactic radiotherapy in 4 dogs with intracranial neoplasia.

    PubMed

    Moon, Alaina Burkard; Heller, Heidi Barnes; Forrest, Lisa

    2016-05-01

    The purpose of this study was to describe the use, and side effects, of a novel stereotactic radiotherapy protocol using TomoTherapy(®) in 4 dogs with confirmed or suspected primary extra-axial intracranial neoplasia. Three fractions of 8 Gy were prescribed. Acute side effects were noted in 1 dog; no late effects were noted. PMID:27152041

  3. 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

  4. 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.

  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. 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.

  7. Multibeam Phased Array Antennas

    NASA Technical Reports Server (NTRS)

    Popovic, Zoya; Romisch, Stefania; Rondineau, Sebastien

    2004-01-01

    In this study, a new architecture for Ka-band multi-beam arrays was developed and demonstrated experimentally. The goal of the investigation was to demonstrate a new architecture that has the potential of reducing the cost as compared to standard expensive phased array technology. The goals of this specific part of the project, as stated in the yearly statement of work in the original proposal are: 1. Investigate bounds on performance of multi-beam lens arrays in terms of beamwidths, volume (size), isolation between beams, number of simultaneous beams, etc. 2. Design a small-scale array to demonstrate the principle. The array will be designed for operation around 3OGHz (Ka-band), with two 10-degree beamwidth beams. 3. Investigate most appropriate way to accomplish fine-tuning of the beam pointing within 5 degrees around the main beam pointing angle.

  8. Medical applications of fast 3D cameras in real-time image-guided radiotherapy (IGRT) of cancer

    NASA Astrophysics Data System (ADS)

    Li, Shidong; Li, Tuotuo; Geng, Jason

    2013-03-01

    Dynamic volumetric medical imaging (4DMI) has reduced motion artifacts, increased early diagnosis of small mobile tumors, and improved target definition for treatment planning. High speed cameras for video, X-ray, or other forms of sequential imaging allow a live tracking of external or internal movement useful for real-time image-guided radiation therapy (IGRT). However, none of 4DMI can track real-time organ motion and no camera has correlated with 4DMI to show volumetric changes. With a brief review of various IGRT techniques, we propose a fast 3D camera for live-video stereovision, an automatic surface-motion identifier to classify body or respiratory motion, a mechanical model for synchronizing the external surface movement with the internal target displacement by combination use of the real-time stereovision and pre-treatment 4DMI, and dynamic multi-leaf collimation for adaptive aiming the moving target. Our preliminary results demonstrate that the technique is feasible and efficient in IGRT of mobile targets. A clinical trial has been initiated for validation of its spatial and temporal accuracies and dosimetric impact for intensity-modulated RT (IMRT), volumetric-modulated arc therapy (VMAT), and stereotactic body radiotherapy (SBRT) of any mobile tumors. The technique can be extended for surface-guided stereotactic needle insertion in biopsy of small lung nodules.

  9. Geometric-model-based segmentation of the prostate and surrounding structures for image-guided radiotherapy

    NASA Astrophysics Data System (ADS)

    Tang, Xiaoli; Jeong, Yongwon; Radke, Richard J.; Chen, George T. Y.

    2004-01-01

    We present a computer vision tool to improve the clinical outcome of patients undergoing radiation therapy for prostate cancer by improving irradiation technique. While intensity modulated radiotherapy (IMRT) allows one to irradiate a specific region in the body with high accuracy, it is still difficult to know exactly where to aim the radiation beam on every day of the 30~40 treatments that are necessary. This paper presents a geometric model-based technique to accurately segment the prostate and other surrounding structures in a daily serial CT image, compensating for daily motion and shape variation. We first acquire a collection of serial CT scans of patients undergoing external beam radiotherapy, and manual segmentation of the prostate and other nearby structures by radiation oncologists. Then we train shape and local appearance models for the structures of interest. When new images are available, an iterative algorithm is applied to locate the prostate and surrounding structures automatically. Our experimental results show that excellent matches can be given to the prostate and surrounding structure. Convergence is declared after 10 iterations. For 256 x 256 images, the mean distance between the hand-segmented contour and the automatically estimated contour is about 1.5 pixels (2.44 mm), with variance about 0.6 pixel (1.24 mm).

  10. 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

  11. 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

  12. 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.

  13. Development of a four-dimensional image-guided radiotherapy system with a gimbaled X-ray head

    SciTech Connect

    Kamino, Yuichiro . E-mail: daisaku_horiuchi@mhi.co.jp; Takayama, Kenji; Kokubo, Masaki; Narita, Yuichiro; Hirai, Etsuro; Kawawda, Noriyuki; Mizowaki, Takashi; Nagata, Yasushi; Nishidai, Takehiro; Hiraoka, Masahiro

    2006-09-01

    Purpose: To develop and evaluate a new four-dimensional image-guided radiotherapy system, which enables precise setup, real-time tumor tracking, and pursuit irradiation. Methods and Materials: The system has an innovative gimbaled X-ray head that enables small-angle ({+-}2.4{sup o}) rotations (pan and tilt) along the two orthogonal gimbals. This design provides for both accurate beam positioning at the isocenter by actively compensating for mechanical distortion and quick pursuit of the target. The X-ray head is composed of an ultralight C-band linear accelerator and a multileaf collimator. The gimbaled X-ray head is mounted on a rigid O-ring structure with an on-board imaging subsystem composed of two sets of kilovoltage X-ray tubes and flat panel detectors, which provides a pair of radiographs, cone beam computed tomography images useful for image guided setup, and real-time fluoroscopic monitoring for pursuit irradiation. Results: The root mean square accuracy of the static beam positioning was 0.1 mm for 360{sup o} of O-ring rotation. The dynamic beam response and positioning accuracy was {+-}0.6 mm for a 0.75 Hz, 40-mm stroke and {+-}0.4 mm for a 2.0 Hz, 8-mm stroke. The quality of the images was encouraging for using the tomography-based setup. Fluoroscopic images were sufficient for monitoring and tracking lung tumors. Conclusions: Key functions and capabilities of our new system are very promising for precise image-guided setup and for tracking and pursuit irradiation of a moving target.

  14. 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

  15. 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

  16. 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.

  17. 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

  18. Performance characteristics of mobile MOSFET dosimeter for kilovoltage X-rays used in image guided radiotherapy.

    PubMed

    Kumar, A Sathish; Singh, I Rabi Raja; Sharma, S D; Ravindran, B Paul

    2015-01-01

    The main objective of this study was to investigate the characteristics of metal oxide semiconductor field effect transistor (MOSFET) dosimeter for kilovoltage (kV) X-ray beams in order to perform the in vivo dosimetry during image guidance in radiotherapy. The performance characteristics of high sensitivity MOSFET dosimeters were investigated for 80, 90, 100, 110, 120, and 125 kV X-ray beams used for imaging in radiotherapy. This study was performed using Clinac 2100 C/D medical electron linear accelerator with on-board imaging and kV cone beam computed tomography system. The characteristics studied in this work include energy dependence, angular dependence, and linearity. The X-ray beam outputs were measured as per American Association of Physicists in Medicine (AAPM) TG 61 recommendations using PTW parallel plate (PP) ionization chamber, which was calibrated in terms of air kerma (Nk) by the National Standard Laboratory. The MOSFET dosimeters were calibrated against the PP ionization chamber for all the kV X-ray beams and the calibration coefficient was found to be 0.11 cGy/mV with a standard deviation of about ±1%. The response of MOSFET was found to be energy independent for the kV X-ray energies used in this study. The response of the MOSFET dosimeter was also found independent of angle of incidence for the gantry angles in the range of 0° to 360° in-air as well as at 3 cm depth in tissue equivalent phantom. PMID:26500397

  19. Phase II Trial of Hypofractionated Image-Guided Intensity-Modulated Radiotherapy for Localized Prostate Adenocarcinoma

    SciTech Connect

    Martin, Jarad M.; Rosewall, Tara; Bayley, Andrew; Bristow, Robert; Chung, Peter; Crook, Juanita; Gospodarowicz, Mary; McLean, Michael; Menard, Cynthia; Milosevic, Michael; Warde, Padraig; Catton, Charles

    2007-11-15

    Purpose: To assess in a prospective trial the feasibility and late toxicity of hypofractionated radiotherapy (RT) for prostate cancer. Methods and Materials: Eligible patients had clinical stage T1c-2cNXM0 disease. They received 60 Gy in 20 fractions over 4 weeks with intensity-modulated radiotherapy including daily on-line image guidance with intraprostatic fiducial markers. Results: Between June 2001 and March 2004, 92 patients were treated with hypofractionated RT. The cohort had a median prostate-specific antigen value of 7.06 ng/mL. The majority had Gleason grade 5-6 (38%) or 7 (59%) disease, and 82 patients had T1c-T2a clinical staging. Overall, 29 patients had low-risk, 56 intermediate-risk, and 7 high-risk disease. Severe acute toxicity (Grade 3-4) was rare, occurring in only 1 patient. Median follow-up was 38 months. According to the Phoenix definition for biochemical failure, the rate of biochemical control at 14 months was 97%. According to the previous American Society for Therapeutic Radiology and Oncology definition, biochemical control at 3 years was 76%. The incidence of late toxicity was low, with no severe (Grade {>=}3) toxicity at the most recent assessment. Conclusions: Hypofractionated RT using 60 Gy in 20 fractions over 4 weeks with image guidance is feasible and is associated with low rates of late bladder and rectal toxicity. At early follow-up, biochemical outcome is comparable to that reported for conventionally fractionated controls. The findings are being tested in an ongoing, multicenter, Phase III trial.

  20. Performance characteristics of mobile MOSFET dosimeter for kilovoltage X-rays used in image guided radiotherapy

    PubMed Central

    Kumar, A. Sathish; Singh, I. Rabi Raja; Sharma, S. D.; Ravindran, B. Paul

    2015-01-01

    The main objective of this study was to investigate the characteristics of metal oxide semiconductor field effect transistor (MOSFET) dosimeter for kilovoltage (kV) X-ray beams in order to perform the in vivo dosimetry during image guidance in radiotherapy. The performance characteristics of high sensitivity MOSFET dosimeters were investigated for 80, 90, 100, 110, 120, and 125 kV X-ray beams used for imaging in radiotherapy. This study was performed using Clinac 2100 C/D medical electron linear accelerator with on-board imaging and kV cone beam computed tomography system. The characteristics studied in this work include energy dependence, angular dependence, and linearity. The X-ray beam outputs were measured as per American Association of Physicists in Medicine (AAPM) TG 61 recommendations using PTW parallel plate (PP) ionization chamber, which was calibrated in terms of air kerma (Nk) by the National Standard Laboratory. The MOSFET dosimeters were calibrated against the PP ionization chamber for all the kV X-ray beams and the calibration coefficient was found to be 0.11 cGy/mV with a standard deviation of about ±1%. The response of MOSFET was found to be energy independent for the kV X-ray energies used in this study. The response of the MOSFET dosimeter was also found independent of angle of incidence for the gantry angles in the range of 0° to 360° in-air as well as at 3 cm depth in tissue equivalent phantom. PMID:26500397

  1. SU-E-J-144: MRI Visualization of a Metallic Fiducial Marker Used for Image Guided Prostate Radiotherapy

    SciTech Connect

    Yee, S; Krauss, D; Yan, D

    2014-06-01

    Purpose: Unlike on the daily CBCT used for the image-guided radiation therapy, the visualization of an implantable metallic fiducial marker on the planning MRI images has been a challenge due to the inherent insensitivity of metal in MRI, and very thin (∼ 1 mm or less) diameter. Here, an MRI technique to visualize a marker used for prostate cancer radiotherapy is reported. Methods: During the MRI acquisitions, a multi-shot turbo spin echo (TSE) technique (TR=3500 ms, TE=8.6 ms, ETL=17, recon voxel=0.42x0.42x3.5 mm3) was acquired in Philips 3T Ingenia together with a T2-weighted multi-shot TSE (TR=5381 ms, TE=110 ms, ETL=17, recon voxel=0.47×0.47×3 mm3) and a balanced turbo field echo (bTFE, flip angle 60, TR=2.76 ms, TE=1.3 ms, 0.85×0.85×3 mm3, NSA=4). In acquiring the MRI to visualize the fiducial marker, a particular emphasis was made to improve the spatial resolution and visibility in the generally dark, inhomogeneous prostate area by adjusting the slice profile ordering and TE values of TSE acquisition (in general, the lower value of TE in TSE acquisition generates a brighter signal but at the cost of high spatial resolution since the k-space, responsible for high spatial resolution, is filled with noisier data). Results: While clearly visible in CT, the marker was not visible in either T2-weighted TSE or bTFE, although the image qualities of both images were superior. In the new TSE acquisition (∼ a proton-density weighted image) adjusted by changing the profile ordering and the TE value, the marker was visible as a negative (but clear) contrast in the magnitude MRI, and as a positive contrast in the imaginary image of the phase-sensitive MRI. Conclusion: A metallic fiducial marker used for image guidance before prostate cancer radiotherapy can be made visible in MRI, which may facilitate more use of MRI in planning and guiding such radiation therapy.

  2. Daily targeting of liver tumors: Screening patients with a mock treatment and using a combination of internal and external fiducials for image-guided respiratory-gated radiotherapy

    SciTech Connect

    Krishnan, Sunil; Briere, Tina Marie; Dong Lei; Murthy, Ravi; Ng, Chaan; Balter, Peter; Mohan, Radhe; Gillin, Michael T.; Beddar, A. Sam

    2007-12-15

    The feasibility and accuracy of using a mock treatment to screen suitable patients for respiratory-gated image-guided radiotherapy was investigated. Radio-opaque fiducials implanted adjacent to the liver tumor were used for online positioning to minimize the systematic error in patient positioning. The consistency in the degree of correlation between the external and internal fiducials was analyzed during a mock treatment. This technique could screen patients for gated therapy, reduce setup inaccuracy, and possibly individualize treatment margins.

  3. 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.

  4. Use of the BrainLAB ExacTrac X-Ray 6D system in image-guided radiotherapy.

    PubMed

    Jin, Jian-Yue; Yin, Fang-Fang; Tenn, Stephen E; Medin, Paul M; Solberg, Timothy D

    2008-01-01

    The ExacTrac X-Ray 6D image-guided radiotherapy (IGRT) system will be described and its performance evaluated. The system is mainly an integration of 2 subsystems: (1) an infrared (IR)-based optical positioning system (ExacTrac) and (2) a radiographic kV x-ray imaging system (X-Ray 6D). The infrared system consists of 2 IR cameras, which are used to monitor reflective body markers placed on the patient's skin to assist in patient initial setup, and an IR reflective reference star, which is attached to the treatment couch and can assist in couch movement with spatial resolution to better than 0.3 mm. The radiographic kV devices consist of 2 oblique x-ray imagers to obtain high-quality radiographs for patient position verification and adjustment. The position verification is made by fusing the radiographs with the simulation CT images using either 3 degree-of-freedom (3D) or 6 degree-of-freedom (6D) fusion algorithms. The position adjustment is performed using the infrared system according to the verification results. The reliability of the fusion algorithm will be described based on phantom and patient studies. The results indicated that the 6D fusion method is better compared to the 3D method if there are rotational deviations between the simulation and setup positions. Recently, the system has been augmented with the capabilities for image-guided positioning of targets in motion due to respiration and for gated treatment of those targets. The infrared markers provide a respiratory signal for tracking and gating of the treatment beam, with the x-ray system providing periodic confirmation of patient position relative to the gating window throughout the duration of the gated delivery. PMID:18456164

  5. Use of the BrainLAB ExacTrac X-Ray 6D System in Image-Guided Radiotherapy

    SciTech Connect

    Jin, J.-Y. Yin Fangfang; Tenn, Stephen E.; Medin, Paul M.; Solberg, Timothy D.

    2008-07-01

    The ExacTrac X-Ray 6D image-guided radiotherapy (IGRT) system will be described and its performance evaluated. The system is mainly an integration of 2 subsystems: (1) an infrared (IR)-based optical positioning system (ExacTrac) and (2) a radiographic kV x-ray imaging system (X-Ray 6D). The infrared system consists of 2 IR cameras, which are used to monitor reflective body markers placed on the patient's skin to assist in patient initial setup, and an IR reflective reference star, which is attached to the treatment couch and can assist in couch movement with spatial resolution to better than 0.3 mm. The radiographic kV devices consist of 2 oblique x-ray imagers to obtain high-quality radiographs for patient position verification and adjustment. The position verification is made by fusing the radiographs with the simulation CT images using either 3 degree-of-freedom (3D) or 6 degree-of-freedom (6D) fusion algorithms. The position adjustment is performed using the infrared system according to the verification results. The reliability of the fusion algorithm will be described based on phantom and patient studies. The results indicated that the 6D fusion method is better compared to the 3D method if there are rotational deviations between the simulation and setup positions. Recently, the system has been augmented with the capabilities for image-guided positioning of targets in motion due to respiration and for gated treatment of those targets. The infrared markers provide a respiratory signal for tracking and gating of the treatment beam, with the x-ray system providing periodic confirmation of patient position relative to the gating window throughout the duration of the gated delivery.

  6. [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

  7. 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.

  8. 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

  9. 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.

  10. MR-guided pulsed high intensity focused ultrasound enhancement of docetaxel combined with radiotherapy for prostate cancer treatment

    NASA Astrophysics Data System (ADS)

    Mu, Zhaomei; Ma, C.-M.; Chen, Xiaoming; Cvetkovic, Dusica; Pollack, Alan; Chen, Lili

    2012-01-01

    The purpose of this study is to evaluate the efficacy of the enhancement of docetaxel by pulsed focused ultrasound (pFUS) in combination with radiotherapy (RT) for treatment of prostate cancer in vivo. LNCaP cells were grown in the prostates of male nude mice. When the tumors reached a designated volume by MRI, tumor bearing mice were randomly divided into seven groups (n = 5): (1) pFUS alone; (2) RT alone; (3) docetaxel alone; (4) docetaxel + pFUS (5) docetaxel + RT (6) docetaxel + pFUS + RT, and (7) control. MR-guided pFUS treatment was performed using a focused ultrasound treatment system (InSightec ExAblate 2000) with a 1.5T GE MR scanner. Animals were treated once with pFUS, docetaxel, RT or their combinations. Docetaxel was given by i.v. injection at 5 mg kg-1 before pFUS. RT was given 2 Gy after pFUS. Animals were euthanized 4 weeks after treatment. Tumor volumes were measured on MRI at 1 and 4 weeks post-treatment. Results showed that triple combination therapies of docetaxel, pFUS and RT provided the most significant tumor growth inhibition among all groups, which may have potential for the treatment of prostate cancer due to an improved therapeutic ratio.

  11. 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

  12. MR-CT registration using a Ni-Ti prostate stent in image-guided radiotherapy of prostate cancer

    SciTech Connect

    Korsager, Anne Sofie; Ostergaard, Lasse Riis; Carl, Jesper

    2013-06-15

    Purpose: In image-guided radiotherapy of prostate cancer defining the clinical target volume often relies on magnetic resonance (MR). The task of transferring the clinical target volume from MR to standard planning computed tomography (CT) is not trivial due to prostate mobility. In this paper, an automatic local registration approach is proposed based on a newly developed removable Ni-Ti prostate stent.Methods: The registration uses the voxel similarity measure mutual information in a two-step approach where the pelvic bones are used to establish an initial registration for the local registration.Results: In a phantom study, the accuracy was measured to 0.97 mm and visual inspection showed accurate registration of all 30 data sets. The consistency of the registration was examined where translation and rotation displacements yield a rotation error of 0.41 Degree-Sign {+-} 0.45 Degree-Sign and a translation error of 1.67 {+-} 2.24 mm.Conclusions: This study demonstrated the feasibility for an automatic local MR-CT registration using the prostate stent.

  13. Magnitude of speed of sound aberration corrections for ultrasound image guided radiotherapy for prostate and other anatomical sites

    SciTech Connect

    Fontanarosa, Davide; Meer, Skadi van der; Bloemen-van Gurp, Esther; Stroian, Gabriela; Verhaegen, Frank

    2012-08-15

    Purpose: The purpose of this work is to assess the magnitude of speed of sound (SOS) aberrations in three-dimensional ultrasound (US) imaging systems in image guided radiotherapy. The discrepancy between the fixed SOS value of 1540 m/s assumed by US systems in human soft tissues and its actual nonhomogeneous distribution in patients produces small but systematic errors of up to a few millimeters in the positions of scanned structures. Methods: A correction, provided by a previously published density-based algorithm, was applied to a set of five prostate, five liver, and five breast cancer patients. The shifts of the centroids of target structures and the change in shape were evaluated. Results: After the correction the prostate cases showed shifts up to 3.6 mm toward the US probe, which may explain largely the reported positioning discrepancies in the literature on US systems versus other imaging modalities. Liver cases showed the largest changes in volume of the organ, up to almost 9%, and shifts of the centroids up to more than 6 mm either away or toward the US probe. Breast images showed systematic small shifts of the centroids toward the US probe with a maximum magnitude of 1.3 mm. Conclusions: The applied correction in prostate and liver cancer patients shows positioning errors of several mm due to SOS aberration; the errors are smaller in breast cancer cases, but possibly becoming more important when breast tissue thickness increases.

  14. Localization Accuracy of the Clinical Target Volume During Image-Guided Radiotherapy of Lung Cancer

    SciTech Connect

    Hugo, Geoffrey D.; Weiss, Elisabeth; Badawi, Ahmed; Orton, Matthew

    2011-10-01

    Purpose: To evaluate the position and shape of the originally defined clinical target volume (CTV) over the treatment course, and to assess the impact of gross tumor volume (GTV)-based online computed tomography (CT) guidance on CTV localization accuracy. Methods and Materials: Weekly breath-hold CT scans were acquired in 17 patients undergoing radiotherapy. Deformable registration was used to propagate the GTV and CTV from the first weekly CT image to all other weekly CT images. The on-treatment CT scans were registered rigidly to the planning CT scan based on the GTV location to simulate online guidance, and residual error in the CTV centroids and borders was calculated. Results: The mean GTV after 5 weeks relative to volume at the beginning of treatment was 77% {+-} 20%, whereas for the prescribed CTV, it was 92% {+-} 10%. The mean absolute residual error magnitude in the CTV centroid position after a GTV-based localization was 2.9 {+-} 3.0 mm, and it varied from 0.3 to 20.0 mm over all patients. Residual error of the CTV centroid was associated with GTV regression and anisotropy of regression during treatment (p = 0.02 and p = 0.03, respectively; Spearman rank correlation). A residual error in CTV border position greater than 2 mm was present in 77% of patients and 50% of fractions. Among these fractions, residual error of the CTV borders was 3.5 {+-} 1.6 mm (left-right), 3.1 {+-} 0.9 mm (anterior-posterior), and 6.4 {+-} 7.5 mm (superior-inferior). Conclusions: Online guidance based on the visible GTV produces substantial error in CTV localization, particularly for highly regressing tumors. The results of this study will be useful in designing margins for CTV localization or for developing new online CTV localization strategies.

  15. The ACTS multibeam antenna

    NASA Technical Reports Server (NTRS)

    Regier, Frank A.

    1992-01-01

    The Advanced Communications Technology Satellite (ACTS) to be launched in 1993 is briefly introduced. Its multibeam antenna, consisting of electrically similar 30 GHz receive and 20 GHz transmit offset Cassegrain systems, both utilizing orthogonal polarizations, is described. Dual polarization is achieved by using one feed assembly for each polarization in conjunction with nested front and back subreflectors, the gridded front subreflector acting as a window for one polarization and a reflector for the other. The antennas produce spot beams with approximately 0.3 degree beamwidth and gains of approximately 50 dbi. High surface accuracy and high edge taper produce low sidelobe levels and high cross-polarization isolation. A brief description is given of several Ka-band components fabricated for ACTS. These include multiflare antenna feedhorns, beam-forming networks utilizing latching ferrite waveguide switches, a 30 GHz HEMT low-noise amplifier and a 20 GHz TWT power amplifier.

  16. The Methanol Multibeam Survey

    NASA Astrophysics Data System (ADS)

    Green, James A.; Cohen, R. J.; Caswell, J. L.; Fuller, G. A.; Brooks, K.; Burton, M. G.; Chrysostomou, A.; Diamond, P. J.; Ellingsen, S. P.; Gray, M. D.; Hoare, M. G.; Masheder, M. R. W.; McClure-Griffiths, N.; Pestalozzi, M.; Phillips, C.; Quinn, L.; Thompson, M. A.; Voronkov, M.; Walsh, A.; Ward-Thompson, D.; Wong-McSweeney, D.; Yates, J. A.; Cox, J.

    2007-03-01

    A new 7-beam methanol multibeam receiver is being used to survey the Galaxy for newly forming massive stars, that are pinpointed by strong methanol maser emission at 6.668 GHz. The receiver, jointly constructed by Jodrell Bank Observatory (JBO) and the Australia Telescope National Facility (ATNF), was successfully commissioned at Parkes in January 2006. The Parkes-Jodrell survey of the Milky Way for methanol masers is two orders of magnitude faster than previous systematic surveys using 30-m class dishes, and is the first systematic survey of the entire Galactic plane. The first 53 days of observations with the Parkes telescope have yielded 518 methanol sources, of which 218 are new discoveries. We present the survey methodology as well as preliminary results and analysis.

  17. The ACTS multibeam antenna

    NASA Astrophysics Data System (ADS)

    Regier, Frank A.

    1992-06-01

    The Advanced Communications Technology Satellite (ACTS) to be launched in 1993 is briefly introduced. Its multibeam antenna, consisting of electrically similar 30 GHz receive and 20 GHz transmit offset Cassegrain systems, both utilizing orthogonal polarizations, is described. Dual polarization is achieved by using one feed assembly for each polarization in conjunction with nested front and back subreflectors, the gridded front subreflector acting as a window for one polarization and a reflector for the other. The antennas produce spot beams with approximately 0.3 degree beamwidth and gains of approximately 50 dbi. High surface accuracy and high edge taper produce low sidelobe levels and high cross-polarization isolation. A brief description is given of several Ka-band components fabricated for ACTS. These include multiflare antenna feedhorns, beam-forming networks utilizing latching ferrite waveguide switches, a 30 GHz HEMT low-noise amplifier and a 20 GHz TWT power amplifier.

  18. 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

  19. 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.

  20. Image-Guided Radiotherapy for Left-Sided Breast Cancer Patients: Geometrical Uncertainty of the Heart

    SciTech Connect

    Topolnjak, Rajko; Borst, Gerben R.; Nijkamp, Jasper

    2012-03-15

    Purpose: To quantify the geometrical uncertainties for the heart during radiotherapy treatment of left-sided breast cancer patients and to determine and validate planning organ at risk volume (PRV) margins. Methods and Materials: Twenty-two patients treated in supine position in 28 fractions with regularly acquired cone-beam computed tomography (CBCT) scans for offline setup correction were included. Retrospectively, the CBCT scans were reconstructed into 10-phase respiration correlated four-dimensional scans. The heart was registered in each breathing phase to the planning CT scan to establish the respiratory heart motion during the CBCT scan ({sigma}{sub resp}). The average of the respiratory motion was calculated as the heart displacement error for a fraction. Subsequently, the systematic ({Sigma}), random ({sigma}), and total random ({sigma}{sub tot}={radical}({sigma}{sup 2}+{sigma}{sub resp}{sup 2})) errors of the heart position were calculated. Based on the errors a PRV margin for the heart was calculated to ensure that the maximum heart dose (D{sub max}) is not underestimated in at least 90% of the cases (M{sub heart} = 1.3{Sigma}-0.5{sigma}{sub tot}). All analysis were performed in left-right (LR), craniocaudal (CC), and anteroposterior (AP) directions with respect to both online and offline bony anatomy setup corrections. The PRV margin was validated by accumulating the dose to the heart based on the heart registrations and comparing the planned PRV D{sub max} to the accumulated heart D{sub max}. Results: For online setup correction, the cardiac geometrical uncertainties and PRV margins were N-Ary-Summation = 2.2/3.2/2.1 mm, {sigma} = 2.1/2.9/1.4 mm, and M{sub heart} = 1.6/2.3/1.3 mm for LR/CC/AP, respectively. For offline setup correction these were N-Ary-Summation = 2.4/3.7/2.2 mm, {sigma} = 2.9/4.1/2.7 mm, and M{sub heart} = 1.6/2.1/1.4 mm. Cardiac motion induced by breathing was {sigma}{sub resp} = 1.4/2.9/1.4 mm for LR/CC/AP. The PRV D{sub max

  1. TH-A-BRF-05: MRI of Individual Lymph Nodes to Guide Regional Breast Radiotherapy

    SciTech Connect

    Heijst, T van; Asselen, B van; Lagendijk, J; Bongard, D van den; Philippens, M

    2014-06-15

    Purpose: In regional radiotherapy (RT) for breast-cancer patients, direct visualization of individual lymph nodes (LNs) may reduce target volumes and Result in lower toxicity (i.e. reduced radiation pneumonitis, arm edema, arm morbidity), relative to standard CT-based delineations. To this end, newly designed magnetic resonance imaging (MRI) sequences were optimized and assessed qualitatively and quantitatively. Methods: In ten healthy female volunteers, a scanning protocol was developed and optimized. Coronal images were acquired in supine RT position positioned on a wedge board on a 1.5 T Ingenia (Philips) wide-bore MRI. In four volunteers the optimized MRI protocol was applied, including a 3-dimensional (3D) T1-weighted (T1w) fast-field-echo (FFE). T2w sequences, including 3D FFE, 3D and 2D fast spin echo (FSE), and diffusion-weighted single-shot echo-planar imaging (DWI) were also performed. Several fatsuppression techniques were used. Qualitative evaluation parameters included LN contrast, motion susceptibility, visibility of anatomical structures, and fat suppression. The number of visible axillary and supraclavicular LNs was also determined. Results: T1 FFE, insensitive to motion, lacked contrast of LNs, which often blended in with soft tissue and blood. T2 FFE showed high contrast, but some LNs were obscured due to motion. Both 2D and 3D FSE were motion-insensitive having high contrast, although some blood remained visible. 2D FSE showed more anatomical details, while in 3D FSE, some blurring occurred. DWI showed high LN contrast, but suffered from geometric distortions and low resolution. Fat suppression by mDixon was the most reliable in regions with magnetic-field inhomogeneities. The FSE sequences showed the highest sensitivity for LN detection. Conclusion: MRI of regional LNs was achieved in volunteers. The FSE techniques were robust and the most sensitive. Our optimized MRI sequences can facilitate direct delineation of individual LNs. This can Result

  2. 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 small target volumes is frequently omitted either due to technical complexity or expected side effects hampering long-term observational studies. We here demonstrate how an affordable industrial micro-CT can be converted into a small animal IGRT device at very low costs. We also demonstrate the proof of principle for the case of partial brain irradiation of mice carrying orthotopic glioblastoma implants. Methods/Materials A commercially available micro-CT originally designed for non-destructive material analysis was used. It consists of a CNC manipulator, a transmission X-ray tube (10–160 kV) and a flat-panel detector, which was used together with custom-made steel collimators (1–5 mm aperture size). For radiation field characterization, an ionization chamber, water-equivalent slab phantoms and radiochromic films were used. A treatment planning tool was implemented using a C++ application. For proof of principle, NOD/SCID/γc−/− mice were orthotopically implanted with U87MG high-grade glioma cells and irradiated using the novel setup. Results The overall symmetry of the radiation field at 150 kV was 1.04±0.02%. The flatness was 4.99±0.63% and the penumbra widths were between 0.14 mm and 0.51 mm. The full width at half maximum (FWHM) ranged from 1.97 to 9.99 mm depending on the collimator aperture size. The dose depth curve along the central axis followed a typical shape of keV photons. Dose rates measured were 10.7 mGy/s in 1 mm and 7.6 mGy/s in 5 mm depth (5 mm collimator aperture size). Treatment of mice with a single dose of 10 Gy was tolerated well and resulted in central tumor necrosis consistent with therapeutic efficacy. Conclusion A conventional industrial micro-CT can be easily modified to allow effective small animal IGRT even of critical target volumes such as the brain. PMID:25993010

  3. On-Board Imaging Validation of Optically Guided Stereotactic Radiosurgery Positioning System for Conventionally Fractionated Radiotherapy for Paranasal Sinus and Skull Base Cancer

    SciTech Connect

    Maxim, Peter G.; Loo, Billy W.; Murphy, James D.; Chu, Karen P.M.; Hsu, Annie; Le, Quynh-Thu

    2011-11-15

    Purpose: To evaluate the positioning accuracy of an optical positioning system for stereotactic radiosurgery in a pilot experience of optically guided, conventionally fractionated, radiotherapy for paranasal sinus and skull base tumors. Methods and Materials: Before each daily radiotherapy session, the positioning of 28 patients was set up using an optical positioning system. After this initial setup, the patients underwent standard on-board imaging that included daily orthogonal kilovoltage images and weekly cone beam computed tomography scans. Daily translational shifts were made after comparing the on-board images with the treatment planning computed tomography scans. These daily translational shifts represented the daily positional error in the optical tracking system and were recorded during the treatment course. For 13 patients treated with smaller fields, a three-degree of freedom (3DOF) head positioner was used for more accurate setup. Results: The mean positional error for the optically guided system in patients with and without the 3DOF head positioner was 1.4 {+-} 1.1 mm and 3.9 {+-} 1.6 mm, respectively (p <.0001). The mean positional error drifted 0.11 mm/wk upward during the treatment course for patients using the 3DOF head positioner (p = .057). No positional drift was observed in the patients without the 3DOF head positioner. Conclusion: Our initial clinical experience with optically guided head-and-neck fractionated radiotherapy was promising and demonstrated clinical feasibility. The optically guided setup was especially useful when used in conjunction with the 3DOF head positioner and when it was recalibrated to the shifts using the weekly portal images.

  4. Learning statistical correlation for fast prostate registration in image-guided radiotherapy

    SciTech Connect

    Shi Yonghong; Liao Shu; Shen Dinggang

    2011-11-15

    Purpose: In adaptive radiation therapy of prostate cancer, fast and accurate registration between the planning image and treatment images of the patient is of essential importance. With the authors' recently developed deformable surface model, prostate boundaries in each treatment image can be rapidly segmented and their correspondences (or relative deformations) to the prostate boundaries in the planning image are also established automatically. However, the dense correspondences on the nonboundary regions, which are important especially for transforming the treatment plan designed in the planning image space to each treatment image space, are remained unresolved. This paper presents a novel approach to learn the statistical correlation between deformations of prostate boundary and nonboundary regions, for rapidly estimating deformations of the nonboundary regions when given the deformations of the prostate boundary at a new treatment image. Methods: The main contributions of the proposed method lie in the following aspects. First, the statistical deformation correlation will be learned from both current patient and other training patients, and further updated adaptively during the radiotherapy. Specifically, in the initial treatment stage when the number of treatment images collected from the current patient is small, the statistical deformation correlation is mainly learned from other training patients. As more treatment images are collected from the current patient, the patient-specific information will play a more important role in learning patient-specific statistical deformation correlation to effectively reflect prostate deformation of the current patient during the treatment. Eventually, only the patient-specific statistical deformation correlation is used to estimate dense correspondences when a sufficient number of treatment images have been acquired from the current patient. Second, the statistical deformation correlation will be learned by using a

  5. Targeting accuracy of an image guided gating system for stereotactic body radiotherapy

    NASA Astrophysics Data System (ADS)

    Tenn, Stephen E.; Solberg, Timothy D.; Medin, Paul M.

    2005-12-01

    Recently, a commercial system capable of x-ray image guided patient positioning and respiratory gated delivery has become available. Here we describe the operational principles of this system and investigate its geometric targeting accuracy under controlled conditions. The system tracks breathing via infrared (IR) detection of reflective markers located on the patient's abdomen. Localization kilovoltage (kV) x-rays are triggered from within the gated delivery window portion of the breathing trace and after positioning, the tumour will cross the linac isocentre during gated delivery. We tested geometric accuracy of this system by localizing and delivering gated fields to a moving phantom. Effects of phantom speed, gating window location, timing errors and phantom rotations on positioning and gating accuracy were investigated. The system delivered gated fields to both a moving and static phantom with equal accuracy. The position of the gating window affects accuracy only to the extent that an asymmetric breathing motion could affect dose distribution within its boundaries. Positioning errors were found to be less then 0.5 ± 0.2 mm for phantom rotations up to 5°. We found and corrected a synchronization error caused by a faulty x-ray duration setting and detected a 60 ± 20 ms time delay in our linear accelerator.

  6. 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

  7. 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.

  8. 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.

  9. Image-Guided Radiotherapy for Liver Cancer Using Respiratory-Correlated Computed Tomography and Cone-Beam Computed Tomography

    SciTech Connect

    Guckenberger, Matthias Sweeney, Reinhart A.; Wilbert, Juergen; Krieger, Thomas; Richter, Anne; Baier, Kurt; Mueller, Gerd; Sauer, Otto; Flentje, Michael

    2008-05-01

    Purpose: To evaluate a novel four-dimensional (4D) image-guided radiotherapy (IGRT) technique in stereotactic body RT for liver tumors. Methods and Materials: For 11 patients with 13 intrahepatic tumors, a respiratory-correlated 4D computed tomography (CT) scan was acquired at treatment planning. The target was defined using CT series reconstructed at end-inhalation and end-exhalation. The liver was delineated on these two CT series and served as a reference for image guidance. A cone-beam CT scan was acquired after patient positioning; the blurred diaphragm dome was interpreted as a probability density function showing the motion range of the liver. Manual contour matching of the liver structures from the planning 4D CT scan with the cone-beam CT scan was performed. Inter- and intrafractional uncertainties of target position and motion range were evaluated, and interobserver variability of the 4D-IGRT technique was tested. Results: The workflow of 4D-IGRT was successfully practiced in all patients. The absolute error in the liver position and error in relation to the bony anatomy was 8 {+-} 4 mm and 5 {+-} 2 mm (three-dimensional vector), respectively. Margins of 4-6 mm were calculated for compensation of the intrafractional drifts of the liver. The motion range of the diaphragm dome was reproducible within 5 mm for 11 of 13 lesions, and the interobserver variability of the 4D-IGRT technique was small (standard deviation, 1.5 mm). In 4 patients, the position of the intrahepatic lesion was directly verified using a mobile in-room CT scanner after application of intravenous contrast. Conclusion: The results of our study have shown that 4D image guidance using liver contour matching between respiratory-correlated CT and cone-beam CT scans increased the accuracy compared with stereotactic positioning and compared with IGRT without consideration of breathing motion.

  10. 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

  11. 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.

  12. Comparison of Spine, Carina, and Tumor as Registration Landmarks for Volumetric Image-Guided Lung Radiotherapy

    SciTech Connect

    Higgins, Jane Bezjak, Andrea; Franks, Kevin; Le, Lisa W.; Cho, B.C.; Payne, David; Bissonnette, Jean-Pierre

    2009-04-01

    Purpose: To assess the feasibility, reproducibility, and accuracy of volumetric lung image guidance using different thoracic landmarks for image registration. Methods and Materials: In 30 lung patients, four independent observers conducted automated and manual image registrations on Day 1 cone-beam computed tomography data sets using the spine, carina, and tumor (720 image registrations). The image registration was timed, and the couch displacements were recorded. The intraclass correlation was used to assess reproducibility, and the Bland-Altman analysis was used to compare the automatic and manual matching methods. Tumor coverage (accuracy) was assessed through grading the tumor position after image matching against the internal target volume and planning target volume. Results: The image-guided process took an average of 1 min for all techniques, with the exception of manual tumor matching, which took 4 min. Reproducibility was greatest for automatic carina matching (intraclass correlation, 0.90-0.93) and lowest for manual tumor matching (intraclass correlation, 0.07-0.43) in the left-right, superoinferior, and anteroposterior directions, respectively. The Bland-Altman analysis showed no significant difference between the automatic and manual registration methods. The tumor was within the internal target volume 62% and 60% of the time and was outside the internal target volume, but within the planning target volume, 38% and 40% of the time after automatic spine and automatic carina matching, respectively. Conclusion: For advanced lung cancer, the spine or carina can be used equally for cone-beam computed tomography image registration without compromising target coverage. The carina was more reproducible than the spine, but additional analysis is required to confirm its validation as a tumor surrogate. Soft-tissue registration is unsuitable at present, given the limitations in contrast resolution and the high interobserver variability.

  13. 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.

  14. An adaptive MR-CT registration method for MRI-guided prostate cancer radiotherapy

    NASA Astrophysics Data System (ADS)

    Zhong, Hualiang; Wen, Ning; Gordon, James J.; Elshaikh, Mohamed A.; Movsas, Benjamin; Chetty, Indrin J.

    2015-04-01

    during the transformation between the MR and CT images and improves the accuracy of the B-spline registrations in the prostate region. The approach will be valuable for the development of high-quality MRI-guided radiation therapy.

  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. The ACTS multibeam antenna

    NASA Astrophysics Data System (ADS)

    Regier, Frank A.

    1992-04-01

    The Advanced Communications Technology Satellite (ACTS) to be launched in 1993 introduces several new technologies including a multibeam antenna (MBA) operating at Ka-band. The satellite is introduced briefly, and then the MBA, consisting of electrically similar 30 GHz received and 20 GHz transmit offset Cassegrain systems utilizing orthogonal linear polarizations, is described. Dual polarization is achieved by using one feed assembly for each polarization in conjunction with nested front and back subreflectors, the gridded front subreflector acting as a window for one polarization and a reflector for the other. The antennas produce spot beams with approximately 0.3 deg beamwidth and gains of approximately 50 dbi. High surface accuracy and high edge taper produce low sidelobe levels and high cross-polarization isolation. A brief description is given of several Ka-band components fabricated for ACTS. These include multiflare antenna feedhorns, beam-forming networks utilizing latching ferrite waveguide switches, a 30 GHz high mobility electron transmitter (HEMT) low-noise amplifier and a 20 GHz TWT power amplifier.

  17. The ACTS multibeam antenna

    NASA Technical Reports Server (NTRS)

    Regier, Frank A.

    1992-01-01

    The Advanced Communications Technology Satellite (ACTS) to be launched in 1993 introduces several new technologies including a multibeam antenna (MBA) operating at Ka-band. The satellite is introduced briefly, and then the MBA, consisting of electrically similar 30 GHz received and 20 GHz transmit offset Cassegrain systems utilizing orthogonal linear polarizations, is described. Dual polarization is achieved by using one feed assembly for each polarization in conjunction with nested front and back subreflectors, the gridded front subreflector acting as a window for one polarization and a reflector for the other. The antennas produce spot beams with approximately 0.3 deg beamwidth and gains of approximately 50 dbi. High surface accuracy and high edge taper produce low sidelobe levels and high cross-polarization isolation. A brief description is given of several Ka-band components fabricated for ACTS. These include multiflare antenna feedhorns, beam-forming networks utilizing latching ferrite waveguide switches, a 30 GHz high mobility electron transmitter (HEMT) low-noise amplifier and a 20 GHz TWT power amplifier.

  18. Multibeam antenna study, phase 1

    NASA Technical Reports Server (NTRS)

    Bellamy, J. L.

    1972-01-01

    A multibeam antenna concept was developed for providing spot beam coverage of the contiguous 48 states. The selection of a suitable antenna concept for the multibeam application and an experimental evaluation of the antenna concept selected are described. The final analysis indicates that the preferred concept is a dual-antenna, circular artificial dielectric lens. A description of the analytical methods is provided, as well as a discussion of the absolute requirements placed on the antenna concepts. Finally, a comparative analysis of reflector antenna off-axis beam performance is presented.

  19. 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

  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. Implementation of Feedback-Guided Voluntary Breath-Hold Gating for Cone Beam CT-Based Stereotactic Body Radiotherapy

    SciTech Connect

    Peng Yong; Vedam, Sastry; Chang, Joe Y.; Gao Song; Sadagopan, Ramaswamy; Bues, Martin; Balter, Peter

    2011-07-01

    Purpose: To analyze tumor position reproducibility of feedback-guided voluntary deep inspiration breath-hold (FGBH) gating for cone beam computed tomography (CBCT)-based stereotactic body radiotherapy (SBRT). Methods and materials: Thirteen early-stage lung cancer patients eligible for SBRT with tumor motion of >1cm were evaluated for FGBH-gated treatment. Multiple FGBH CTs were acquired at simulation, and single FGBH CBCTs were also acquired prior to each treatment. Simulation CTs and treatment CBCTs were analyzed to quantify reproducibility of tumor positions during FGBH. Benefits of FGBH gating compared to treatment during free breathing, as well treatment with gating at exhalation, were examined for lung sparing, motion margins, and reproducibility of gross tumor volume (GTV) position relative to nonmoving anatomy. Results: FGBH increased total lung volumes by 1.5 times compared to free breathing, resulting in a proportional drop in total lung volume receiving 10 Gy or more. Intra- and inter-FGBH reproducibility of GTV centroid positions at simulation were 1.0 {+-} 0.5 mm, 1.3 {+-} 1.0 mm, and 0.6 {+-} 0.4 mm in the anterior-posterior (AP), superior-inferior (SI), and left-right lateral (LR) directions, respectively, compared to more than 1 cm of tumor motion at free breathing. During treatment, inter-FGBH reproducibility of the GTV centroid with respect to bony anatomy was 1.2 {+-} 0.7 mm, 1.5 {+-} 0.8 mm, and 1.0 {+-} 0.4 mm in the AP, SI, and LR directions. In addition, the quality of CBCTs was improved due to elimination of motion artifacts, making this technique attractive for poorly visualized tumors, even with small motion. Conclusions: The extent of tumor motion at normal respiration does not influence the reproducibility of the tumor position under breath hold conditions. FGBH-gated SBRT with CBCT can improve the reproducibility of GTV centroids, reduce required margins, and minimize dose to normal tissues in the treatment of mobile tumors.

  2. 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.

  3. Intrafraction Variation of Mean Tumor Position During Image-Guided Hypofractionated Stereotactic Body Radiotherapy for Lung Cancer

    SciTech Connect

    Shah, Chirag; Grills, Inga S.; Kestin, Larry L.; McGrath, Samuel; Ye Hong; Martin, Shannon K.; Yan Di

    2012-04-01

    Purpose: Prolonged delivery times during daily cone-beam computed tomography (CBCT)-guided lung stereotactic body radiotherapy (SBRT) introduce concerns regarding intrafraction variation (IFV) of the mean target position (MTP). The purpose of this study was to evaluate the magnitude of the IFV-MTP and to assess target margins required to compensate for IFV and postonline CBCT correction residuals. Patient, treatment, and tumor characteristics were analyzed with respect to their impact on IFV-MTP. Methods and Materials: A total of 126 patients with 140 tumors underwent 659 fractions of lung SBRT. Dose prescribed was 48 or 60 Gy in 12 Gy fractions. Translational target position correction of the MTP was performed via onboard CBCT. IFV-MTP was measured as the difference in MTP between the postcorrection CBCT and the posttreatment CBCT excluding residual error. Results: IFV-MTP was 0.2 {+-} 1.8 mm, 0.1 {+-} 1.9 mm, and 0.01 {+-} 1.5 mm in the craniocaudal, anteroposterior, and mediolateral dimensions and the IFV-MTP vector was 2.3 {+-} 2.1 mm. Treatment time and excursion were found to be significant predictors of IFV-MTP. An IFV-MTP vector greater than 2 and 5 mm was seen in 40.8% and 7.2% of fractions, respectively. IFV-MTP greater than 2 mm was seen in heavier patients with larger excursions and longer treatment times. Significant differences in IFV-MTP were seen between immobilization devices. The stereotactic frame immobilization device was found to be significantly less likely to have an IFV-MTP vector greater than 2 mm compared with the alpha cradle, BodyFIX, and hybrid immobilization devices. Conclusions: Treatment time and respiratory excursion are significantly associated with IFV-MTP. Significant differences in IFV-MTP were found between immobilization devices. Target margins for IFV-MTP plus post-correction residuals are dependent on immobilization device with 5-mm uniform margins being acceptable for the frame immobilization device.

  4. Clinical Evaluation of Positioning Verification Using Digital Tomosynthesis and Bony Anatomy and Soft Tissues for Prostate Image-Guided Radiotherapy

    SciTech Connect

    Yoo, Sua Wu, Q. Jackie; Godfrey, Devon; Yan Hui; Ren Lei; Das, Shiva; Lee, William R.; Yin Fangfang

    2009-01-01

    Purpose: To evaluate on-board digital tomosynthesis (DTS) for patient positioning vs. two-dimensional (2D) radiography and three-dimensional cone beam (CBCT). Methods and Materials: A total of 92 image sessions from 9 prostate cancer patients were analyzed. An on-board image set was registered to a corresponding reference image set. Four pairs of image sets were used: digitally reconstructed radiographs vs. on-board orthogonal paired radiographs for the 2D method, coronal-reference DTS vs. on-board coronal DTS for the coronal-DTS method, sagittal-reference DTS vs. on-board sagittal DTS for the sagittal-DTS method, and planning CT vs. CBCT for the CBCT method. The registration results were compared. Results: The systematic errors in all methods were <1 mm/1{sup o}. When registering the bony anatomy, the mean vector difference was 0.21 {+-} 0.11 cm between 2D and CBCT, 0.11 {+-} 0.08 cm between CBCT and coronal DTS, and 0.14 {+-} 0.07 cm between CBCT and sagittal DTS. The correlation between CBCT to DTS was stronger (coefficient = 0.92-0.95) than the correlation between 2D and CBCT or DTS (coefficient = 0.81-0.83). When registering the soft tissue, the mean vector difference was 0.18 {+-} 0.11 cm between CBCT and coronal DTS and 0.29 {+-} 0.17 cm between CBCT and sagittal DTS. The correlation coefficient of CBCT to sagittal DTS and to coronal DTS was 0.84 and 0.92, respectively. Conclusion: DTS could provide equivalent results to CBCT when the bony anatomy is used as landmarks for prostate image-guided radiotherapy. For soft tissue-based positioning verification, coronal DTS produced equivalent results to CBCT, but sagittal DTS alone was insufficient. DTS could allow for comparable soft tissue-based target localization with faster scanning time and a lower imaging dose compared with CBCT.

  5. [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

  6. 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

  7. WE-G-BRF-06: Positron Emission Tomography (PET)-Guided Dynamic Lung Tumor Tracking for Cancer Radiotherapy: First Patient Simulations

    SciTech Connect

    Yang, J; Loo, B; Graves, E; Yamamoto, T; Keall, P

    2014-06-15

    Purpose: PET-guided dynamic tumor tracking is a novel concept of biologically targeted image guidance for radiotherapy. A dynamic tumor tracking algorithm based on list-mode PET data has been developed and previously tested on dynamic phantom data. In this study, we investigate if dynamic tumor tracking is clinically feasible by applying the method to lung cancer patient PET data. Methods: PET-guided tumor tracking estimates the target position of a segmented volume in PET images reconstructed continuously from accumulated coincidence events correlated with external respiratory motion, simulating real-time applications, i.e., only data up to the current time point is used to estimate the target position. A target volume is segmented with a 50% threshold, consistently, of the maximum intensity in the predetermined volume of interest. Through this algorithm, the PET-estimated trajectories are quantified from four lung cancer patients who have distinct tumor location and size. The accuracy of the PET-estimated trajectories is evaluated by comparing to external respiratory motion because the ground-truth of tumor motion is not known in patients; however, previous phantom studies demonstrated sub-2mm accuracy using clinically derived 3D tumor motion. Results: The overall similarity of motion patterns between the PET-estimated trajectories and the external respiratory traces implies that the PET-guided tracking algorithm can provide an acceptable level of targeting accuracy. However, there are variations in the tracking accuracy between tumors due to the quality of the segmentation which depends on target-to-background ratio, tumor location and size. Conclusion: For the first time, a dynamic tumor tracking algorithm has been applied to lung cancer patient PET data, demonstrating clinical feasibility of real-time tumor tracking for integrated PET-linacs. The target-to-background ratio is a significant factor determining accuracy: screening during treatment planning would

  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. Protocols for calibrating multibeam sonar.

    PubMed

    Foote, Kenneth G; Chu, Dezhang; Hammar, Terence R; Baldwin, Kenneth C; Mayer, Larry A; Hufnagle, Lawrence C; Jech, J Michael

    2005-04-01

    Development of protocols for calibrating multibeam sonar by means of the standard-target method is documented. Particular systems used in the development work included three that provide the water-column signals, namely the SIMRAD SM2000/90- and 200-kHz sonars and RESON SeaBat 8101 sonar, with operating frequency of 240 kHz. Two facilities were instrumented specifically for the work: a sea well at the Woods Hole Oceanographic Institution and a large, indoor freshwater tank at the University of New Hampshire. Methods for measuring the transfer characteristics of each sonar, with transducers attached, are described and illustrated with measurement results. The principal results, however, are the protocols themselves. These are elaborated for positioning the target, choosing the receiver gain function, quantifying the system stability, mapping the directionality in the plane of the receiving array and in the plane normal to the central axis, measuring the directionality of individual beams, and measuring the nearfield response. General preparations for calibrating multibeam sonars and a method for measuring the receiver response electronically are outlined. Advantages of multibeam sonar calibration and outstanding problems, such as that of validation of the performance of multibeam sonars as configured for use, are mentioned. PMID:15898644

  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. 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.

  12. Automatic localization of the prostate for on-line or off-line image-guided radiotherapy

    SciTech Connect

    Smitsmans, Monique H.P.; Wolthaus, Jochem W.H.; Artignan, Xavier; Bois, Josien de; Jaffray, David A.; Lebesque, Joos V.; Herk, Marcel van . E-mail: portal@nki.nl

    2004-10-01

    Purpose: With higher radiation dose, higher cure rates have been reported in prostate cancer patients. The extra margin needed to account for prostate motion, however, limits the level of dose escalation, because of the presence of surrounding organs at risk. Knowledge of the precise position of the prostate would allow significant reduction of the treatment field. Better localization of the prostate at the time of treatment is therefore needed, e.g. using a cone-beam computed tomography (CT) system integrated with the linear accelerator. Localization of the prostate relies upon manual delineation of contours in successive axial CT slices or interactive alignment and is fairly time-consuming. A faster method is required for on-line or off-line image-guided radiotherapy, because of prostate motion, for patient throughput and efficiency. Therefore, we developed an automatic method to localize the prostate, based on 3D gray value registration. Methods and materials: A study was performed on conventional repeat CT scans of 19 prostate cancer patients to develop the methodology to localize the prostate. For each patient, 8-13 repeat CT scans were made during the course of treatment. First, the planning CT scan and the repeat CT scan were registered onto the rigid bony structures. Then, the delineated prostate in the planning CT scan was enlarged by an optimum margin of 5 mm to define a region of interest in the planning CT scan that contained enough gray value information for registration. Subsequently, this region was automatically registered to a repeat CT scan using 3D gray value registration to localize the prostate. The performance of automatic prostate localization was compared to prostate localization using contours. Therefore, a reference set was generated by registering the delineated contours of the prostates in all scans of all patients. Gray value registrations that showed large differences with respect to contour registrations were detected with a {chi

  13. 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

  14. 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

  15. Image-Guided Radiotherapy (IGRT) for Prostate Cancer Comparing kV Imaging of Fiducial Markers With Cone Beam Computed Tomography (CBCT)

    SciTech Connect

    Barney, Brandon M.; Lee, R. Jeffrey; Handrahan, Diana; Welsh, Keith T.; Cook, J. Taylor; Sause, William T.

    2011-05-01

    Purpose: To present our single-institution experience with image-guided radiotherapy comparing fiducial markers and cone-beam computed tomography (CBCT) for daily localization of prostate cancer. Methods and Materials: From April 2007 to October 2008, 36 patients with prostate cancer received intensity-modulated radiotherapy with daily localization by use of implanted fiducials. Orthogonal kilovoltage (kV) portal imaging preceded all 1244 treatments. Cone-beam computed tomography images were also obtained before 286 treatments (23%). Shifts in the anterior-posterior (AP), superior-inferior (SI), and left-right (LR) dimensions were made from kV fiducial imaging. Cone-beam computed tomography shifts based on soft tissues were recorded. Shifts were compared by use of Bland-Altman limits of agreement. Mean and standard deviation of absolute differences were also compared. A difference of 5 mm or less was acceptable. Subsets including start date, body mass index, and prostate size were analyzed. Results: Of 286 treatments, 81 (28%) resulted in a greater than 5.0-mm difference in one or more dimensions. Mean differences in the AP, SI, and LR dimensions were 3.4 {+-} 2.6 mm, 3.1 {+-} 2.7 mm, and 1.3 {+-} 1.6 mm, respectively. Most deviations occurred in the posterior (fiducials, 78%; CBCT, 59%), superior (79%, 61%), and left (57%, 63%) directions. Bland-Altman 95% confidence intervals were -4.0 to 9.3 mm for AP, -9.0 to 5.3 mm for SI, and -4.1 to 3.9 mm for LR. The percentages of shift agreements within {+-}5 mm were 72.4% for AP, 72.7% for SI, and 97.2% for LR. Correlation between imaging techniques was not altered by time, body mass index, or prostate size. Conclusions: Cone-beam computed tomography and kV fiducial imaging are similar; however, more than one-fourth of CBCT and kV shifts differed enough to affect target coverage. This was even more pronounced with smaller margins (3 mm). Fiducial imaging requires less daily physician input, is less time-consuming, and is

  16. Assessment of contrast enhanced respiration managed cone-beam CT for image guided radiotherapy of intrahepatic tumors

    SciTech Connect

    Jensen, Nikolaj K. G.; Stewart, Errol; Lock, Michael; Fisher, Barbara; Kozak, Roman; Chen, Jeff; Lee, Ting-Yim; Wong, Eugene

    2014-05-15

    Purpose: Contrast enhancement and respiration management are widely used during image acquisition for radiotherapy treatment planning of liver tumors along with respiration management at the treatment unit. However, neither respiration management nor intravenous contrast is commonly used during cone-beam CT (CBCT) image acquisition for alignment prior to radiotherapy. In this study, the authors investigate the potential gains of injecting an iodinated contrast agent in combination with respiration management during CBCT acquisition for liver tumor radiotherapy. Methods: Five rabbits with implanted liver tumors were subjected to CBCT with and without motion management and contrast injection. The acquired CBCT images were registered to the planning CT to determine alignment accuracy and dosimetric impact. The authors developed a simulation tool for simulating contrast-enhanced CBCT images from dynamic contrast enhanced CT imaging (DCE-CT) to determine optimal contrast injection protocols. The tool was validated against contrast-enhanced CBCT of the rabbit subjects and was used for five human patients diagnosed with hepatocellular carcinoma. Results: In the rabbit experiment, when neither motion management nor contrast was used, tumor centroid misalignment between planning image and CBCT was 9.2 mm. This was reduced to 2.8 mm when both techniques were employed. Tumors were not visualized in clinical CBCT images of human subjects. Simulated contrast-enhanced CBCT was found to improve tumor contrast in all subjects. Different patients were found to require different contrast injections to maximize tumor contrast. Conclusions: Based on the authors’ animal study, respiration managed contrast enhanced CBCT improves IGRT significantly. Contrast enhanced CBCT benefits from patient specific tracer kinetics determined from DCE-CT.

  17. X-ray volumetric imaging in image-guided radiotherapy: The new standard in on-treatment imaging

    SciTech Connect

    McBain, Catherine A.; Henry, Ann M. . E-mail: catherine.mcbain@christie-tr.nwest.nhs.uk; Sykes, Jonathan; Amer, Ali; Marchant, Tom; Moore, Christopher M.; Davies, Julie; Stratford, Julia; McCarthy, Claire; Porritt, Bridget; Williams, Peter; Khoo, Vincent S.; Price, Pat

    2006-02-01

    Purpose: X-ray volumetric imaging (XVI) for the first time allows for the on-treatment acquisition of three-dimensional (3D) kV cone beam computed tomography (CT) images. Clinical imaging using the Synergy System (Elekta, Crawley, UK) commenced in July 2003. This study evaluated image quality and dose delivered and assessed clinical utility for treatment verification at a range of anatomic sites. Methods and Materials: Single XVIs were acquired from 30 patients undergoing radiotherapy for tumors at 10 different anatomic sites. Patients were imaged in their setup position. Radiation doses received were measured using TLDs on the skin surface. The utility of XVI in verifying target volume coverage was qualitatively assessed by experienced clinicians. Results: X-ray volumetric imaging acquisition was completed in the treatment position at all anatomic sites. At sites where a full gantry rotation was not possible, XVIs were reconstructed from projection images acquired from partial rotations. Soft-tissue definition of organ boundaries allowed direct assessment of 3D target volume coverage at all sites. Individual image quality depended on both imaging parameters and patient characteristics. Radiation dose ranged from 0.003 Gy in the head to 0.03 Gy in the pelvis. Conclusions: On-treatment XVI provided 3D verification images with soft-tissue definition at all anatomic sites at acceptably low radiation doses. This technology sets a new standard in treatment verification and will facilitate novel adaptive radiotherapy techniques.

  18. Image-guided radiotherapy for prostate cancer by CT-linear accelerator combination: Prostate movements and dosimetric considerations

    SciTech Connect

    Wong, James R.; Grimm, Lisa; Oren, Reva

    2005-02-01

    Purpose: Multiple studies have indicated that the prostate is not stationary and can move as much as 2 cm. Such prostate movements are problematic for intensity-modulated radiotherapy, with its associated tight margins and dose escalation. Because of these intrinsic daily uncertainties, a relative generous 'margin' is necessary to avoid marginal misses. Using the CT-linear accelerator combination in the treatment suite (Primatom, Siemens), we found that the daily intrinsic prostate movements can be easily corrected before each radiotherapy session. Dosimetric calculations were performed to evaluate the amount of discrepancy of dose to the target if no correction was done for prostate movement. Methods and materials: The Primatom consists of a Siemens Somatom CT scanner and a Siemens Primus linear accelerator installed in the same treatment suite and sharing a common table/couch. The patient is scanned by the CT scanner, which is movable on a pair of horizontal rails. During scanning, the couch does not move. The exact location of the prostate, seminal vesicles, and rectum are identified and localized. These positions are then compared with the planned positions. The daily movement of the prostate and rectum were corrected for and a new isocenter derived. The patient was treated immediately using the new isocenter. Results: Of the 108 patients with primary prostate cancer studied, 540 consecutive daily CT scans were performed during the last part of the cone down treatment. Of the 540 scans, 46% required no isocenter adjustments for the AP-PA direction, 54% required a shift of {>=}3 mm, 44% required a shift of >5 mm, and 15% required a shift of >10 mm. In the superoinferior direction, 27% required a shift of >3 mm, 25% required a shift of >5 mm, and 4% required a shift of >10 mm. In the right-left direction, 34% required a shift of >3 mm, 24% required a shift of >5 mm, and 5% required a shift of >10 mm. Dosimetric calculations for a typical case of prostate cancer

  19. The clinical feasibility and performance of an orthogonal X-ray imaging system for image-guided radiotherapy in nasopharyngeal cancer patients: Comparison with cone-beam CT.

    PubMed

    Zhao, Li-Rong; Zhou, Yi-Bing; Li, Guang-Hui; Li, Qi-Ming; Yang, Ding-Qiang; Li, Han-Xu; Wan, Jiu-Qing; Sun, Jian-Guo

    2016-01-01

    The demand for greater accuracy of intensity-modulated radiotherapy (IMRT) has driven the development of more advanced verification systems for image-guided radiotherapy (IGRT). The purpose of this study is to investigate setup discrepancies measured between an orthogonal X-ray guidance system (XGS-10) and cone-beam computed tomography (CBCT) of Varian in the IMRT of patients with nasopharyngeal cancer (NPC). The setup errors measured by XGS-10 and CBCT at the treatment unit with respect to the planning CTs were recorded for 30 patients with NPC. The differences in residual setup errors between XGS-10 system and CBCT were computed and quantitatively analyzed. The time of image acquisition and image registration was recorded. The radiation doses delivered by CBCT and XGS-10 were measured using PTW0.6CC ionization chambers and a water phantom. The differences between setup errors measured by the XGS-10 system and CBCT were generally <1.5 mm for translations, indicating a reasonably good agreement between the two systems for patients with NPC in the translation directions of A-P (P = 0.856), L-R (P = 0.856) and S-I (P = 0.765). Moreover, compared with CBCT, XGS-10 took much shorter image acquisition and registration time (P <0.001) and delivered only a small fraction of extra radiation dose to the patients (P <0.001). These results indicate that XGS-10 offers high localization accuracy similar to CBCT and additional benefits including prompt imaging process, low imaging radiation exposure, real time monitoring, which therefore represents a potential attractive alternative to CBCT for clinical use. PMID:26703446

  20. Image-Guided Radiotherapy for Prostate Cancer: A Prospective Trial of Concomitant Boost Using Indium-111-Capromab Pendetide (ProstaScint) Imaging

    SciTech Connect

    Wong, William W.; Schild, Steven E.; Vora, Sujay A.; Ezzell, Gary A.; Nguyen, Ba D.; Ram, Panol C.; Roarke, Michael C.

    2011-11-15

    Purpose: To evaluate, in a prospective study, the use of {sup 111}In-capromab pendetide (ProstaScint) scan to guide the delivery of a concomitant boost to intraprostatic region showing increased uptake while treating the entire gland with intensity-modulated radiotherapy for localized prostate cancer. Methods and Materials: From September 2002 to November 2005, 71 patients were enrolled. Planning pelvic CT and {sup 111}In-capromab pendetide scan images were coregistered. The entire prostate gland received 75.6 Gy/42 fractions, whereas areas of increased uptake in {sup 111}In-capromab pendetide scan received 82 Gy. For patients with T3/T4 disease, or Gleason score {>=}8, or prostate-specific antigen level >20 ng/mL, 12 months of adjuvant androgen deprivation therapy was given. In January 2005 the protocol was modified to give 6 months of androgen deprivation therapy to patients with a prostate-specific antigen level of 10-20 ng/mL or Gleason 7 disease. Results: Thirty-one patients had low-risk, 30 had intermediate-risk, and 10 had high-risk disease. With a median follow-up of 66 months, the 5-year biochemical control rates were 94% for the entire cohort and 97%, 93%, and 90% for low-, intermediate-, and high-risk groups, respectively. Maximum acute and late urinary toxicities were Grade 2 for 38 patients (54%) and 28 patients (39%) and Grade 3 for 1 and 3 patients (4%), respectively. One patient had Grade 4 hematuria. Maximum acute and late gastrointestinal toxicities were Grade 2 for 32 patients (45%) and 15 patients (21%), respectively. Most of the side effects improved with longer follow-up. Conclusion: Concomitant boost to areas showing increased uptake in {sup 111}In-capromab pendetide scan to 82 Gy using intensity-modulated radiotherapy while the entire prostate received 75.6 Gy was feasible and tolerable, with 94% biochemical control rate at 5 years.

  1. Image-guided robotic stereotactic body radiotherapy for benign spinal tumors: theUniversity of California San Francisco preliminary experience.

    PubMed

    Sahgal, A; Chou, D; Ames, C; Ma, L; Lamborn, K; Huang, K; Chuang, C; Aiken, A; Petti, P; Weinstein, P; Larson, D

    2007-12-01

    We evaluate our preliminary experience using the Cyberknife Radiosurgery System in treating benign spinal tumors. A retrospective review of 16 consecutively treated patients, comprising 19 benign spinal tumors, was performed. Histologic types included neurofibroma [11], chordoma [4], hemangioma [2], and meningioma [2]. Three patients had Neurofibromatosis Type 1 (NF1). Only one tumor, recurrent chordoma, had been previously irradiated, and as such not considered in the local failure analysis. Local failure, for the remaining 18 tumors, was based clinically on symptom progression and/or tumor enlargement based on imaging. Indications for spine stereotactic body radiotherapy (SBRT) consisted of either adjuvant to subtotal resection (5/19), primary treatment alone (12/19), boost following external beam radiotherapy (1/19), and salvage following previous radiation (1/19). Median tumor follow-up is 25 months (2-37), and one patient (with NF1) died at 12 months from a stroke. The median total dose, number of fractions, and prescription isodose was 21 Gy (10-30 Gy), 3 fx (1-5 fx), 80% (42-87%). The median tumor volume was 7.6 cc (0.2-274.1 cc). The median V100 (volume V receiving 100% of the prescribed dose) and maximum tumor dose was 95% (77-100%) and 26.7 Gy (15.4-59.7 Gy), respectively. Three tumors progressed at 2, 4, and 36 months post-SR (n=18). Two tumors were neurofibromas (both in NF1 patients), and the third was an intramedullary hemangioblastoma. Based on imaging, two tumors had MRI documented progression, three had regressed, and 13 were unchanged (n=18). With short follow-up, local control following Cyberknife spine SBRT for benign spinal tumors appear acceptable. PMID:17994789

  2. 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

  3. 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.

  4. [Use of gold radionuclide markers implanted into the prostate for image-guided radiotherapy in prostate cancer: side effects caused by the marker implantation].

    PubMed

    Kliton, Jorgo; Ágoston, Péter; Szabó, Zoltán; Major, Tibor; Polgár, Csaba

    2014-09-01

    The purpose of the study was to introduce the use of the gold radiopaque markers implanted into the prostate for image-guided radiotherapy of prostate cancer patients and to present the side effects caused by the marker implantation. Between November 2011 and November 2013, three radiopaque, gold-plated markers (Best Medical International, Springfield, VA, USA, 1.0 mm x 3.0 mm) were implanted transperineally into the prostate of 60 patients under transrectal ultrasound guidance. Local anaesthesia was performed in all patients. A week after the procedure the patients filled in a questionnaire regarding the pain, dysuria, urinary frequency, nycturia, rectal bleeding, haematuria, haematospermia or fever symptoms caused by the implantation. The pain caused by the intervention was scored on a 1-10 scale, where 1 was a very weak and 10 was an unbearable pain. Ten days after the implantation a treatment planning CT was performed and subsequently patients started intensity-modulated radiation therapy (IMRT) within one week. During the treatments markers were used for daily verification and correction of patient's setup. No patients experienced fever or infection. Based on the questionnaires nobody experienced dysuria or rectal bleeding after implantation. Among the 60 patients studied, five (8 %) had haematospermia, nine (15 %) haematuria, which lasted in average of 3.4 and 1.8 days, respectively. The average pain score on 1-10 scale was 4.2 (range: 0-9). After the marker implantation 18 patients (30%) reported less, 10 patients (17%) more, and 27 patients (45%) equal amount of pain compared to biopsy. Five patients, who had a biopsy performed under general anaesthesia, did not answer this question. None of the patients needed analgesics after implantation. The gold marker implantation implemented for image-guided radiotherapy was well tolerated under a local anaesthesia. The complications were limited, rate and frequency of perioperative pain was comparable to the pain

  5. 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.

  6. Dosimetric characterization of a multileaf collimator for a new four-dimensional image-guided radiotherapy system with a gimbaled x-ray head, MHI-TM2000

    SciTech Connect

    Nakamura, Mitsuhiro; Sawada, Akira; Ishihara, Yoshitomo; Takayama, Kenji; Mizowaki, Takashi; Kaneko, Shuji; Yamashita, Mikiko; Tanabe, Hiroaki; Kokubo, Masaki; Hiraoka, Masahiro

    2010-09-15

    Purpose: To present the dosimetric characterization of a multileaf collimator (MLC) for a new four-dimensional image-guided radiotherapy system with a gimbaled x-ray head, MHI-TM2000. Methods: MHI-TM2000 has an x-ray head composed of an ultrasmall linear accelerator guide and a system-specific MLC. The x-ray head can rotate along the two orthogonal gimbals (pan and tilt rotations) up to {+-}2.5 deg., which swings the beam up to {+-}41.9 mm in each direction from the isocenter on the isocenter plane perpendicular to the beam. The MLC design is a single-focus type, has 30 pairs of 5 mm thick leaves at the isocenter, and produces a maximum field size of 150x150 mm{sup 2}. Leaf height and length are 110 and 260 mm, respectively. Each leaf end is circular, with a radius of curvature of 370 mm. The distance that each leaf passes over the isocenter is 77.5 mm. Radiation leakage between adjacent leaves is minimized by an interlocking tongue-and-groove (T and G) arrangement with the height of the groove part 55 mm. The dosimetric characterizations including field characteristics, leaf position accuracy, leakage, and T and G effect were evaluated using a well-commissioned 6 MV photon beam, EDR2 films (Kodak, Rochester, NY), and water-equivalent phantoms. Furthermore, the field characteristics and leaf position accuracy were evaluated under conditions of pan or tilt rotation. Results: The differences between nominal and measured field sizes were within {+-}0.5 mm. Although the penumbra widths were greater with wider field size, the maximum width was <5.5 mm even for the fully opened field. Compared to the results of field characteristics without pan or tilt rotation, the variation in field size, penumbra width, flatness, and symmetry was within {+-}1 mm/1% at the maximum pan or tilt rotational angle. The leaf position accuracy was 0.0{+-}0.1 mm, ranging from -0.3 to 0.2 mm at four gantry angles of 0 deg., 90 deg., 180 deg., and 270 deg. with and without pan or tilt rotation

  7. Fluorine-18-Labeled Fluoromisonidazole Positron Emission and Computed Tomography-Guided Intensity-Modulated Radiotherapy for Head and Neck Cancer: A Feasibility Study

    PubMed Central

    Lee, Nancy Y.; Mechalakos, James G.; Nehmeh, Sadek; Lin, Zhixiong; Squire, Olivia D.; Cai, Shangde; Chan, Kelvin; Zanzonico, Pasquale B.; Greco, Carlo; Ling, Clifton C.; Humm, John L.; Schöder, Heiko

    2010-01-01

    Purpose Hypoxia renders tumor cells radioresistant, limiting locoregional control from radiotherapy (RT). Intensity-modulated RT (IMRT) allows for targeting of the gross tumor volume (GTV) and can potentially deliver a greater dose to hypoxic subvolumes (GTVh) while sparing normal tissues. A Monte Carlo model has shown that boosting the GTVh increases the tumor control probability. This study examined the feasibility of fluorine-18–labeled fluoromisonidazole positron emission tomography/computed tomography (18F-FMISO PET/CT)–guided IMRT with the goal of maximally escalating the dose to radioresistant hypoxic zones in a cohort of head and neck cancer (HNC) patients. Methods and Materials 18F-FMISO was administered intravenously for PET imaging. The CT simulation, fluorodeoxyglucose PET/CT, and 18F-FMISO PET/CT scans were co-registered using the same immobilization methods. The tumor boundaries were defined by clinical examination and available imaging studies, including fluorodeoxyglucose PET/CT. Regions of elevated 18F-FMISO uptake within the fluorodeoxyglucose PET/CT GTV were targeted for an IMRT boost. Additional targets and/or normal structures were contoured or transferred to treatment planning to generate 18F-FMISO PET/CT-guided IMRT plans. Results The heterogeneous distribution of 18F-FMISO within the GTV demonstrated variable levels of hypoxia within the tumor. Plans directed at performing 18F-FMISO PET/CT–guided IMRT for 10 HNC patients achieved 84 Gy to the GTVh and 70 Gy to the GTV, without exceeding the normal tissue tolerance. We also attempted to deliver 105 Gy to the GTVh for 2 patients and were successful in 1, with normal tissue sparing. Conclusion It was feasible to dose escalate the GTVh to 84 Gy in all 10 patients and in 1 patient to 105 Gy without exceeding the normal tissue tolerance. This information has provided important data for subsequent hypoxia-guided IMRT trials with the goal of further improving locoregional control in HNC

  8. 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.

  9. Ultrasound-Guided Transrectal Implantation of Gold Markers for Prostate Localization During External Beam Radiotherapy: Complication Rate and Risk Factors

    SciTech Connect

    Langenhuijsen, Johan F.; Lin, Emile N.J.T. van Kiemeney, Lambertus A.; Vight, Lisette P. van der; McColl, Gill; Visser, Andries G.; Witjes, J. Alfred

    2007-11-01

    Purpose: To report the complication rate and risk factors of transrectally implanted gold markers, used for prostate position verification and correction procedures. Methods and Materials: In 209 consecutive men with localized prostate cancer, four gold markers (1 x 7 mm) were inserted under ultrasound guidance in an outpatient setting, and the toxicity was analyzed. All patients received a questionnaire regarding complications after marker implantation. The complications and risk factors were further evaluated by reviewing the medical charts. Results: Of the 209 men, 13 (6.2%) had a moderate complication, consisting of pain and fever that resolved after treatment with oral medication. In 1.9% of the men, minor voiding complaints were observed. Other minor transient complications, defined as hematuria lasting >3 days, hematospermia, and rectal bleeding, occurred in 3.8%, 18.5%, and 9.1% of the patients, respectively. These complications were seen more often in patients with advanced tumor stage, younger age, and shorter duration of hormonal therapy. Conclusion: Transrectal gold marker implantation for high-precision prostate radiotherapy is a safe and well-tolerated procedure.

  10. Outcome of Elderly Patients with Meningioma after Image-Guided Stereotactic Radiotherapy: A Study of 100 Cases

    PubMed Central

    Budach, Volker; Graaf, Lukas; Gollrad, Johannes; Badakhshi, Harun

    2015-01-01

    Introduction. Incidence of meningioma increases with age. Surgery has been the mainstay treatment. Elderly patients, however, are at risk of severe morbidity. Therefore, we conducted this study to analyze long-term outcomes of linac-based fractionated stereotactic radiotherapy (FSRT) for older adults (aged ≥65 years) with meningioma and determine prognostic factors. Materials and Methods. Between October 1998 and March 2009, 100 patients (≥65, median age, 71 years) were treated with FSRT for meningioma. Two patients were lost to follow-up. Eight patients each had grade I and grade II meningiomas, and five patients had grade III meningiomas. The histology was unknown in 77 cases (grade 0). Results. The median follow-up was 37 months, and 3-year, 5-year, and 10-year progression-free survival (PFS) rates were 93.7%, 91.1%, and 82%. Patients with grade 0/I meningioma showed 3- and 5-year PFS rates of 98.4% and 95.6%. Patients with grade II or III meningiomas showed 3-year PFS rates of 36%. 93.8% of patients showed local tumor control. Multivariate analysis did not indicate any significant prognostic factors. Conclusion. FSRT may play an important role as a noninvasive and safe method in the clinical management of older patients with meningioma. PMID:26101778

  11. Clinical Feasibility of Using an EPID in cine Mode for Image-Guided Verification of Stereotactic Body Radiotherapy

    SciTech Connect

    Berbeco, Ross I.

    2007-09-01

    Purpose: To introduce a novel method for monitoring tumor location during stereotactic body radiotherapy (SBRT) while the treatment beam is on by using a conventional electronic portal imaging device (EPID). Methods and Materials: In our clinic, selected patients were treated under a phase I institutional review board-approved SBRT protocol for limited hepatic metastases from solid tumors. Before treatment planning multiple gold fiducial markers were implanted on the periphery of the tumor. During treatment the EPID was used in cine mode to collect the exit radiation and produce a sequence of images for each field. An in-house program was developed for calculating the location of the fiducials and their relative distance to the planned locations. Results: Three case studies illustrate the utility of the technique. Patient A exhibited a systematic shift of 4 mm during one of the treatment beams. Patient B showed an inferior drift of the target of approximately 1 cm from the time of setup to the end of the fraction. Patient C had a poor setup on the first day of treatment that was quantified and accounted for on subsequent treatment days. Conclusions: Target localization throughout each treatment beam can be quickly assessed with the presented technique. Treatment monitoring with an EPID in cine mode is shown to be a clinically feasible and useful tool.

  12. 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.

  13. Atlas-guided generation of pseudo-CT images for MRI-only and hybrid PET-MRI-guided radiotherapy treatment planning.

    PubMed

    Arabi, Hossein; Koutsouvelis, Nikolaos; Rouzaud, Michel; Miralbell, Raymond; Zaidi, Habib

    2016-09-01

    Magnetic resonance imaging (MRI)-guided attenuation correction (AC) of positron emission tomography (PET) data and/or radiation therapy (RT) treatment planning is challenged by the lack of a direct link between MRI voxel intensities and electron density. Therefore, even if this is not a trivial task, a pseudo-computed tomography (CT) image must be predicted from MRI alone. In this work, we propose a two-step (segmentation and fusion) atlas-based algorithm focusing on bone tissue identification to create a pseudo-CT image from conventional MRI sequences and evaluate its performance against the conventional MRI segmentation technique and a recently proposed multi-atlas approach. The clinical studies consisted of pelvic CT, PET and MRI scans of 12 patients with loco-regionally advanced rectal disease. In the first step, bone segmentation of the target image is optimized through local weighted atlas voting. The obtained bone map is then used to assess the quality of deformed atlases to perform voxel-wise weighted atlas fusion. To evaluate the performance of the method, a leave-one-out cross-validation (LOOCV) scheme was devised to find optimal parameters for the model. Geometric evaluation of the produced pseudo-CT images and quantitative analysis of the accuracy of PET AC were performed. Moreover, a dosimetric evaluation of volumetric modulated arc therapy photon treatment plans calculated using the different pseudo-CT images was carried out and compared to those produced using CT images serving as references. The pseudo-CT images produced using the proposed method exhibit bone identification accuracy of 0.89 based on the Dice similarity metric compared to 0.75 achieved by the other atlas-based method. The superior bone extraction resulted in a mean standard uptake value bias of  -1.5  ±  5.0% (mean  ±  SD) in bony structures compared to  -19.9  ±  11.8% and  -8.1  ±  8.2% achieved by MRI segmentation-based (water

  14. Definition and visualisation of regions of interest in post-prostatectomy image-guided intensity modulated radiotherapy

    SciTech Connect

    Bell, Linda J Cox, Jennifer; Eade, Thomas; Rinks, Marianne; Kneebone, Andrew

    2014-09-15

    Standard post-prostatectomy radiotherapy (PPRT) image verification uses bony anatomy alignment. However, the prostate bed (PB) moves independently of bony anatomy. Cone beam computed tomography (CBCT) can be used to soft tissue match, so radiation therapists (RTs) must understand pelvic anatomy and PPRT clinical target volumes (CTV). The aims of this study are to define regions of interest (ROI) to be used in soft tissue matching image guidance and determine their visibility on planning CT (PCT) and CBCT. Published CTV guidelines were used to select ROIs. The PCT scans (n = 23) and CBCT scans (n = 105) of 23 post-prostatectomy patients were reviewed. Details on ROI identification were recorded. Eighteen patients had surgical clips. All ROIs were identified on PCTs at least 90% of the time apart from mesorectal fascia (MF) (87%) due to superior image quality. When surgical clips are present, the seminal vesicle bed (SVB) was only seen in 2.3% of CBCTs and MF was unidentifiable. Most other structures were well identified on CBCT. The anterior rectal wall (ARW) was identified in 81.4% of images and penile bulb (PB) in 68.6%. In the absence of surgical clips, the MF and SVB were always identified; the ARW was identified in 89.5% of CBCTs and PB in 73.7%. Surgical clips should be used as ROIs when present to define SVB and MF. In the absence of clips, SVB, MF and ARW can be used. RTs must have a strong knowledge of soft tissue anatomy and PPRT CTV to ensure coverage and enable soft tissue matching.

  15. Performance of a Novel Repositioning Head Frame for Gamma Knife Perfexion and Image-Guided Linac-Based Intracranial Stereotactic Radiotherapy

    SciTech Connect

    Ruschin, Mark; Nayebi, Nazanin; Carlsson, Per; Brown, Kevin

    2010-09-01

    Purpose: To evaluate the geometric positioning and immobilization performance of a vacuum bite-block repositioning head frame (RHF) system for Perfexion (PFX-SRT) and linac-based intracranial image-guided stereotactic radiotherapy (SRT). Methods and Materials: Patients with intracranial tumors received linac-based image-guided SRT using the RHF for setup and immobilization. Three hundred thirty-three fractions of radiation were delivered in 12 patients. The accuracy of the RHF was estimated for linac-based SRT with online cone-beam CT (CBCT) and for PFX-SRT with a repositioning check tool (RCT) and offline CBCT. The RCT's ability to act as a surrogate for anatomic position was estimated through comparison to CBCT image matching. Immobilization performance was evaluated daily with pre- and postdose delivery CBCT scans and RCT measurements. Results: The correlation coefficient between RCT- and CBCT-reported displacements was 0.59, 0.75, 0.79 (Right, Superior, and Anterior, respectively). For image-guided linac-based SRT, the mean three-dimensional (3D) setup error was 0.8 mm with interpatient ({Sigma}) and interfraction ({sigma}) variations of 0.1 and 0.4 mm, respectively. For PFX-SRT, the initial, uncorrected mean 3D positioning displacement in stereotactic coordinates was 2.0 mm, with {Sigma} = 1.1 mm and {sigma} = 0.8 mm. Considering only RCT setups <1mm (PFX action level) the mean 3D positioning displacement reduced to 1.3 mm, with {Sigma} = 0.9 mm and {sigma} = 0.4 mm. The largest contributing systematic uncertainty was in the superior-inferior direction (mean displacement = -0.5 mm; {Sigma} = 0.9 mm). The largest mean rotation was 0.6{sup o} in pitch. The mean 3D intrafraction motion was 0.4 {+-} 0.3 mm. Conclusion: The RHF provides excellent immobilization for intracranial SRT and PFX-SRT. Some small systematic uncertainties in stereotactic positioning exist and must be considered when generating PFX-SRT treatment plans. The RCT provides reasonable surrogacy

  16. Imaging and dosimetric errors in 4D PET/CT-guided radiotherapy from patient-specific respiratory patterns: a dynamic motion phantom end-to-end study

    NASA Astrophysics Data System (ADS)

    Bowen, S. R.; Nyflot, M. J.; Herrmann, C.; Groh, C. M.; Meyer, J.; Wollenweber, S. D.; Stearns, C. W.; Kinahan, P. E.; Sandison, G. A.

    2015-05-01

    delivery under a dose painting paradigm is feasible within an integrated respiratory motion phantom workflow. For a limited set of cases, the magnitude of errors was comparable during PET/CT imaging and treatment delivery without motion compensation. Errors were moderately mitigated during PET/CT imaging and significantly mitigated during RT delivery with motion compensation. This dynamic motion phantom end-to-end workflow provides a method for quality assurance of 4D PET/CT-guided radiotherapy, including evaluation of respiratory motion compensation methods during imaging and treatment delivery.

  17. SU-E-J-210: Characterizing Tissue Equivalent Materials for the Development of a Dual MRI-CT Heterogeneous Anthropomorphic Phantom Designed Specifically for MRI Guided Radiotherapy Systems

    SciTech Connect

    Steinmann, A; Stafford, R; Yung, J; Followill, D

    2015-06-15

    Purpose: MRI guided radiotherapy (MRIgRT) is an emerging technology which will eventually require a proficient quality auditing system. Due to different principles in which MR and CT acquire images, there is a need for a multi-imaging-modality, end-to-end QA phantom for MRIgRT. The purpose of this study is to identify lung, soft tissue, and tumor equivalent substitutes that share similar human-like CT and MR properties (i.e. Hounsfield units and relaxation times). Methods: Materials of interested such as common CT QA phantom materials, and other proprietary gels/silicones from Polytek, SmoothOn, and CompositeOne were first scanned on a GE 1.5T Signa HDxT MR. Materials that could be seen on both T1-weighted and T2-weighted images were then scanned on a GE Lightspeed RT16 CT simulator and a GE Discovery 750HD CT scanner and their HU values were then measured. The materials with matching HU values of lung (−500 to −700HU), muscle (+40HU) and soft tissue (+100 to +300HU) were further scanned on GE 1.5T Signa HDx to measure their T1 and T2 relaxation times from varying parameters of TI and TE. Results: Materials that could be visualized on T1-weighted and T2-weighted images from a 1.5T MR unit and had an appropriate average CT number, −650, −685, 46,169, and 168 HUs were: compressed cork saturated with water, Polytek Platsil™ Gel-00 combined with mini styrofoam balls, radiotherapy bolus material, SmoothOn Dragon-Skin™ and SmoothOn Ecoflex™, respectively. Conclusion: Post processing analysis is currently being performed to accurately map T1 and T2 values for each material tested. From previous MR visualization and CT examinations it is expected that Dragon-Skin™, Ecoflex™ and bolus will have values consistent with tissue and tumor substitutes. We also expect compressed cork statured with water, and Polytek™-styrofoam combination to have approximate T1 and T2 values suitable for lung-equivalent materials.

  18. 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

  19. 11C choline PET guided salvage radiotherapy with volumetric modulation arc therapy and hypofractionation for recurrent prostate cancer after HIFU failure: preliminary results of tolerability and acute toxicity.

    PubMed

    Alongi, Filippo; Liardo, Rocco L E; Iftode, Cristina; Lopci, Egesta; Villa, Elisa; Comito, Tiziana; Tozzi, Angelo; Navarria, Pierina; Ascolese, Anna M; Mancosu, Pietro; Tomatis, Stefano; Bellorofonte, Carlo; Arturo, Chiti; Scorsetti, Marta

    2014-10-01

    The purpose of this work was to evaluate tolerance, feasibility and acute toxicity in patients undergoing salvage radiotherapy after high-intensity focused ultrasound (HIFU) failure. From 2005 to 2011 a total of 15 patients were treated with HIFU as primary radical treatment. Between July 2011 and February 2013, all 15 patients presented biochemical relapse after HIFU and 11C choline PET documenting intrapostatic-only failure. Salvage EBRT was performed with moderate hypofractionation schedule in 28 fractions with volumetric modulation arc therapy (VMAT). Genito-urinary (GU) and rectal and bowel toxicity were scored by common terminology criteria for adverse events version 4 (CTCAE V.4) scale. Biochemical response was assessed by ASTRO Phoenix criteria. Median age of patients was 67 years (range: 53-85). The median Gleason score was 7 (range: 6-9). The median prostate specific antigen (PSA) at the time of biochemical relapse after HIFU was 5.2 ng/mL (range: 2-64.2). Seven of the 15 patients received androgen deprivation therapy (ADT) started after HIFU failure, interrupted before 11C choline PET and radiotherapy. Median prescribed dose was 71.4 Gy (range: 71.4-74.2 Gy) in 28 fractions. No radiation related major upper gastrointestinal (GI), rectal and GU toxicity were experienced. GU, acute grade 1 and grade 2 toxicities were recorded in 7/15 and 4/15 respectively; bowel acute grade 1 and grade 2 toxicities in 4/15 and 1/15; rectal acute grade 1 and grade 2 toxicities in 3/15 and 2/15 respectively. No grade 3 or greater acute or late toxicities occurred. Biochemical control was assessed in 12/15 (80%) patients. With a median follow up of 12 months, three out of 15 patients, with biochemical relapse, showed lymph-nodal recurrence. Our early clinical results and biochemical data confirm the feasibility and show a good tolerance of the 11C choline PET guided salvage radiation therapy after HIFU failure. The findings of low acute toxicity is encouraging, but longer

  20. Imaging and dosimetric errors in 4D PET/CT-guided radiotherapy from patient-specific respiratory patterns: a dynamic motion phantom end-to-end study

    PubMed Central

    Bowen, S R; Nyflot, M J; Hermann, C; Groh, C; Meyer, J; Wollenweber, S D; Stearns, C W; Kinahan, P E; Sandison, G A

    2015-01-01

    planning, and RT delivery under a dose painting paradigm is feasible within an integrated respiratory motion phantom workflow. For a limited set of cases, the magnitude of errors was comparable during PET/CT imaging and treatment delivery without motion compensation. Errors were moderately mitigated during PET/CT imaging and significantly mitigated during RT delivery with motion compensation. This dynamic motion phantom end-to-end workflow provides a method for quality assurance of 4D PET/CT-guided radiotherapy, including evaluation of respiratory motion compensation methods during imaging and treatment delivery. PMID:25884892

  1. Accuracy and efficiency of an infrared based positioning and tracking system for patient set-up and monitoring in image guided radiotherapy

    NASA Astrophysics Data System (ADS)

    Jia, Jing; Xu, Gongming; Pei, Xi; Cao, Ruifen; Hu, Liqin; Wu, Yican

    2015-03-01

    monitoring during image guided radiotherapy treatments.

  2. 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.

  3. Tissue feature-based intra-fractional motion tracking for stereoscopic x-ray image guided radiotherapy

    NASA Astrophysics Data System (ADS)

    Xie, Yaoqin; Xing, Lei; Gu, Jia; Liu, Wu

    2013-06-01

    Real-time knowledge of tumor position during radiation therapy is essential to overcome the adverse effect of intra-fractional organ motion. The goal of this work is to develop a tumor tracking strategy by effectively utilizing the inherent image features of stereoscopic x-ray images acquired during dose delivery. In stereoscopic x-ray image guided radiation delivery, two orthogonal x-ray images are acquired either simultaneously or sequentially. The essence of markerless tumor tracking is the reliable identification of inherent points with distinct tissue features on each projection image and their association between two images. The identification of the feature points on a planar x-ray image is realized by searching for points with high intensity gradient. The feature points are associated by using the scale invariance features transform descriptor. The performance of the proposed technique is evaluated by using images of a motion phantom and four archived clinical cases acquired using either a CyberKnife equipped with a stereoscopic x-ray imaging system, or a LINAC equipped with an onboard kV imager and an electronic portal imaging device. In the phantom study, the results obtained using the proposed method agree with the measurements to within 2 mm in all three directions. In the clinical study, the mean error is 0.48 ± 0.46 mm for four patient data with 144 sequential images. In this work, a tissue feature-based tracking method for stereoscopic x-ray image guided radiation therapy is developed. The technique avoids the invasive procedure of fiducial implantation and may greatly facilitate the clinical workflow.

  4. Determination of action thresholds for electromagnetic tracking system-guided hypofractionated prostate radiotherapy using volumetric modulated arc therapy

    SciTech Connect

    Zhang, Pengpeng; Mah, Dennis; Happersett, Laura; Cox, Brett; Hunt, Margie; Mageras, Gig

    2011-07-15

    Purpose: Hypofractionated prostate radiotherapy may benefit from both volumetric modulated arc therapy (VMAT) due to shortened treatment time and intrafraction real-time monitoring provided by implanted radiofrequency(RF) transponders. The authors investigate dosimetrically driven action thresholds (whether treatment needs to be interrupted and patient repositioned) in VMAT treatment with electromagnetic (EM) tracking. Methods: VMAT plans for five patients are generated for prescription doses of 32.5 and 42.5 Gy in five fractions. Planning target volume (PTV) encloses the clinical target volume (CTV) with a 3 mm margin at the prostate-rectal interface and 5 mm elsewhere. The VMAT delivery is modeled using 180 equi-spaced static beams. Intrafraction prostate motion is simulated in the plan by displacing the beam isocenter at each beam assuming rigid organ motion according to a previously recorded trajectory of the transponder centroid. The cumulative dose delivered in each fraction is summed over all beams. Two sets of 57 prostate motion trajectories were randomly selected to form a learning and a testing dataset. Dosimetric end points including CTV D95%, rectum wall D1cc, bladder wall D1cc, and urethra Dmax, are analyzed against motion characteristics including the maximum amplitude of the anterior-posterior (AP), superior-inferior (SI), and left-right components. Action thresholds are triggered when intrafraction motion causes any violations of dose constraints to target and organs at risk (OAR), so that treatment is interrupted and patient is repositioned. Results: Intrafraction motion has a little effect on CTV D95%, indicating PTV margins are adequate. Tight posterior and inferior action thresholds around 1 mm need to be set in a patient specific manner to spare organs at risk, especially when the prescription dose is 42.5 Gy. Advantages of setting patient specific action thresholds are to reduce false positive alarms by 25% when prescription dose is low, and

  5. Status of Multi-Beam Long Trace- Profiler Development

    NASA Technical Reports Server (NTRS)

    Gubarev, Mikhail V.; Kilaru, Kiranmayee; Merthe, Daniel J.; Kester, Thomas; McKinney, Wayne R.; Takacs, Peter Z.; Eng, Ron; Dahir, Andrew; Yashchuk, Valeriy V.

    2013-01-01

    A multi-beam LTP is under development at MSFC in collaboration with Lawrence Berkeley National laboratory and Brookhaven National Laboratory. The Multi-beam LTP has been fully assembled. First tests of the MBLTP has demonstrated the feasibility of the multibeam approach. The calibrations are under way. The MBLTP is intended to be used for metrology support of the deterministic polishing experiments.

  6. Estimate of the shielding effect on secondary cancer risk due to cone-beam CT in image-guided radiotherapy

    NASA Astrophysics Data System (ADS)

    Sung, Jiwon; Baek, Tae Seong; Yoon, Myonggeun; Kim, Dong Wook; Kim, Dong Hyun

    2014-09-01

    This study evaluated the effect of a simple shielding method using a thin lead sheet on the imaging dose caused by cone-beam computed tomography (CBCT) in image-guided radiation therapy (IGRT). Reduction of secondary doses from CBCT was measured using a radio-photoluminescence glass dosimeter (RPLGD) placed inside an anthropomorphic phantom. The entire body, except for the region scanned by using CBCT, was shielded by wrapping it with a 2-mm lead sheet. Changes in secondary cancer risk due to shielding were calculated using BEIR VII models. 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 1.6, 11.5, and 12.7 persons per 100,000, respectively. These findings suggest that a simple, thin-lead-sheet-based shielding method can effectively decrease secondary doses to out-of-field regions for CBCT, which reduces the lifetime cancer risk on average by 9 per 100,000 patients.

  7. First Clinical Release of an Online, Adaptive, Aperture-Based Image-Guided Radiotherapy Strategy in Intensity-Modulated Radiotherapy to Correct for Inter- and Intrafractional Rotations of the Prostate

    SciTech Connect

    Deutschmann, Heinz; Kametriser, Gerhard; Steininger, Philipp; Scherer, Philipp; Schoeller, Helmut; Gaisberger, Christoph; Mooslechner, Michaela; Mitterlechner, Bernhard; Weichenberger, Harald; Fastner, Gert; Wurstbauer, Karl; Jeschke, Stephan; Forstner, Rosemarie; Sedlmayer, Felix

    2012-08-01

    Purpose: We developed and evaluated a correction strategy for prostate rotations using direct adaptation of segments in intensity-modulated radiotherapy (IMRT). Method and Materials: Implanted fiducials (four gold markers) were used to determine interfractional translations, rotations, and dilations of the prostate. We used hybrid imaging: The markers were automatically detected in two pretreatment planar X-ray projections; their actual position in three-dimensional space was reconstructed from these images at first. The structure set comprising prostate, seminal vesicles, and adjacent rectum wall was transformed accordingly in 6 degrees of freedom. Shapes of IMRT segments were geometrically adapted in a class solution forward-planning approach, derived within seconds on-site and treated immediately. Intrafractional movements were followed in MV electronic portal images captured on the fly. Results: In 31 of 39 patients, for 833 of 1013 fractions (supine, flat couch, knee support, comfortably full bladder, empty rectum, no intraprostatic marker migrations >2 mm of more than one marker), the online aperture adaptation allowed safe reduction of margins clinical target volume-planning target volume (prostate) down to 5 mm when only interfractional corrections were applied: Dominant L-R rotations were found to be 5.3 Degree-Sign (mean of means), standard deviation of means {+-}4.9 Degree-Sign , maximum at 30.7 Degree-Sign . Three-dimensional vector translations relative to skin markings were 9.3 {+-} 4.4 mm (maximum, 23.6 mm). Intrafractional movements in 7.7 {+-} 1.5 min (maximum, 15.1 min) between kV imaging and last beam's electronic portal images showed further L-R rotations of 2.5 Degree-Sign {+-} 2.3 Degree-Sign (maximum, 26.9 Degree-Sign ), and three-dimensional vector translations of 3.0 {+-}3.7 mm (maximum, 10.2 mm). Addressing intrafractional errors could further reduce margins to 3 mm. Conclusion: We demonstrated the clinical feasibility of an online

  8. Electronic portal imaging vs kilovoltage imaging in fiducial marker image-guided radiotherapy for prostate cancer: an analysis of set-up uncertainties

    PubMed Central

    Gill, S; Thomas, J; Fox, C; Kron, T; Thompson, A; Chander, S; Williams, S; Tai, K H; Duchesne, G; Foroudi, F

    2012-01-01

    Objectives The purpose of this study was to compare interfraction prostate displacement data between electronic portal imaging (EPI) and kilovoltage imaging (KVI) treatment units and discuss the impact of any difference on margin calculations for prostate cancer image-guided radiotherapy (IGRT). Methods Prostate interfraction displacement data was collected prospectively for the first 4 fractions in 333 patients treated with IGRT with daily pre-treatment EPI or KVI orthogonal imaging. Displacement was recorded in the anteroposterior (AP), left–right (LR) and superoinferior (SI) directions. The proportion of displacement <3 mm and the difference in median absolute displacements were calculated in all directions. Results 1088 image pairs were analysed in total, 448 by EPI and 640 by KVI. There were 23% (95% confidence interval [CI] 18–28%) more displacements under 3 mm for EPI than for KVI in the AP direction, 14% (95% CI 10–19%) more in the LR direction and 10% (95% CI 5–15%) more in the SI direction. The differences in absolute median displacement (KVI>EPI) were AP 1 mm, LR 1 mm and SI 0.5 mm. Wilcoxon rank-sum test showed that distributions were significantly different for all three dimensions (p<0.0001 for AP and LR and p=0.02 for SI). Conclusion EPI has a statistically significant smaller set-up error distribution than KVI. We would expect that, because fiducial marker imaging is less clear for EPI, the clinical target volume to planning target volume margin would be greater when using IGRT; however, relying wholly on displacement data gives the opposite result. We postulate that this is owing to observer bias, which is not accounted for in margin calculation formulas. PMID:21976627

  9. Interfractional Prostate Shifts: Review of 1870 Computed Tomography (CT) Scans Obtained During Image-Guided Radiotherapy Using CT-on-Rails for the Treatment of Prostate Cancer

    SciTech Connect

    Wong, James R. Gao Zhanrong; Uematsu, Minoru; Merrick, Scott; Machernis, Nolan P.; Chen, Timothy; Cheng, C.W.

    2008-12-01

    Purpose: To review 1870 CT scans of interfractional prostate shift obtained during image-guided radiotherapy. Methods and Materials: A total of 1870 pretreatment CT scans were acquired with CT-on-rails, and the corresponding shift data for 329 patients with prostate cancer were analyzed. Results: Of the 1870 scans reviewed, 44% required no setup adjustments in the anterior-posterior (AP) direction, 14% had shifts of 3-5 mm, 29% had shifts of 6-10 mm, and 13% had shifts of >10 mm. In the superior-inferior direction, 81% had no adjustments, 2% had shifts of 3-5 mm, 15% had shifts of 6-10 mm, and 2% had shifts of >10 mm. In the left-right direction, 65% had no adjustment, 13% had shifts of 3-5 mm, 17% had shifts of 6-10 mm, and 5% had shifts of >10 mm. Further analysis of the first 66 consecutive patients divided into three groups according to body mass index indicates that the shift in the AP direction for the overweight subgroup was statistically larger than those for the control and obese subgroups (p < 0.05). The interfractional shift in the lateral direction for the obese group (1 SD, 5.5 mm) was significantly larger than those for the overweight and control groups (4.1 and 2.9 mm, respectively) (p < 0.001). Conclusions: These data demonstrate that there is a significantly greater shift in the AP direction than in the lateral and superior-inferior directions for the entire patient group. Overweight and obese patient groups show a significant difference from the control group in terms of prostate shift.

  10. Does Image-Guided Radiotherapy Improve Toxicity Profile in Whole Pelvic-Treated High-Risk Prostate Cancer? Comparison Between IG-IMRT and IMRT

    SciTech Connect

    Chung, Hans T. Xia Ping; Chan, Linda W.; Park-Somers, Eileen; Roach, Mack

    2009-01-01

    Purpose: To evaluate the impact of adding image-guided (IG) technique to intensity-modulated radiotherapy (IMRT) on dosimetric avoidance of organs at risk (OAR) and acute toxicities. Methods and Materials: A total of 25 consecutively treated patients (10 from National University Hospital and 15 from University of California San Francisco) with high-risk prostate cancer formed the study cohort. All received definitive IMRT with prophylactic nodal RT. Similar IMRT contouring and planning techniques were used at both centers. At University of California, San Francisco, intraprostatic fiducial markers were used for daily pretreatment on-line corrections (IG-IMRT). In contrast, at the National University Hospital, no fiducial markers were used (IMRT). At University of California, San Francisco, the planning target volume margins to the prostate were 2-3 mm. At the National University Hospital, they were 1 cm circumferentially, except for 0.5 cm posteriorly. The acute rectal and bladder toxicities and dosimetric endpoints to the planning target volume and organs at risk were compared. Results: The planning target volume dose coverage was not significantly different between IMRT and IG-IMRT for the prostate, seminal vesicles, and lymph nodes. The volume of rectum and bladder receiving {>=}40, {>=}60, and {>=}70 Gy were all significantly less using IG-IMRT (p <0.001). IG-IMRT yielded lower acute Radiation Therapy Oncology Group Grade 2 rectal (80% vs. 13%, p = 0.004) and bladder (60% vs. 13%, p = 0.014) toxicities. Conclusions: IG-IMRT, using daily target localization with fiducial markers, permits the use of smaller margins and correspondingly lower doses to the organs at risk, such as the rectum and bladder. These tangible gains appear to translate into lower clinically significant toxicities.

  11. SU-E-J-151: Dosimetric Evaluation of DIR Mapped Contours for Image Guided Adaptive Radiotherapy with 4D Cone-Beam CT

    SciTech Connect

    Balik, S; Weiss, E; Williamson, J; Hugo, G; Jan, N; Zhang, L; Roman, N; Christensen, G

    2014-06-01

    Purpose: To estimate dosimetric errors resulting from using contours deformably mapped from planning CT to 4D cone beam CT (CBCT) images for image-guided adaptive radiotherapy of locally advanced non-small cell lung cancer (NSCLC). Methods: Ten locally advanced non-small cell lung cancer (NSCLC) patients underwent one planning 4D fan-beam CT (4DFBCT) and weekly 4DCBCT scans. Multiple physicians delineated the gross tumor volume (GTV) and normal structures in planning CT images and only GTV in CBCT images. Manual contours were mapped from planning CT to CBCTs using small deformation, inverse consistent linear elastic (SICLE) algorithm for two scans in each patient. Two physicians reviewed and rated the DIR-mapped (auto) and manual GTV contours as clinically acceptable (CA), clinically acceptable after minor modification (CAMM) and unacceptable (CU). Mapped normal structures were visually inspected and corrected if necessary, and used to override tissue density for dose calculation. CTV (6mm expansion of GTV) and PTV (5mm expansion of CTV) were created. VMAT plans were generated using the DIR-mapped contours to deliver 66 Gy in 33 fractions with 95% and 100% coverage (V66) to PTV and CTV, respectively. Plan evaluation for V66 was based on manual PTV and CTV contours. Results: Mean PTV V66 was 84% (range 75% – 95%) and mean CTV V66 was 97% (range 93% – 100%) for CAMM scored plans (12 plans); and was 90% (range 80% – 95%) and 99% (range 95% – 100%) for CA scored plans (7 plans). The difference in V66 between CAMM and CA was significant for PTV (p = 0.03) and approached significance for CTV (p = 0.07). Conclusion: The quality of DIR-mapped contours directly impacted the plan quality for 4DCBCT-based adaptation. Larger safety margins may be needed when planning with auto contours for IGART with 4DCBCT images. Reseach was supported by NIH P01CA116602.

  12. The Effect of Radiotherapy on Ultrasound-Guided Fine Needle Aspiration Biopsy and the Ultrasound Characteristics of Neck Lymph Nodes in Oral Cancer Patients after Primary Treatment

    PubMed Central

    Lo, Wu-Chia; Cheng, Po-Wen; Wang, Chi-Te; Shueng, Pei-Wei; Hsieh, Chen-Hsi; Chang, Yih-Leong; Liao, Li-Jen

    2016-01-01

    Objectives To investigate the effect of radiotherapy (RT) on ultrasound-guided fine needle aspiration (USgFNA) and sonographic characteristics in the assessment of cervical lymph nodes (LNs) in oral squamous cell carcinoma (OSCC) patients after primary treatment. Materials and Methods 88 treated OSCC patients underwent 111 USgFNAs of the neck LNs after US evaluation. Among them, 48 USgFNAs were performed on 40 patients following RT and 63 USgFNAs on 48 patients without previous RT. The results of USgFNA and the US characteristics were compared between these two groups. Results USgFNA had a sensitivity of 88.0%, specificity of 91.4%, positive predictive value (PPV) of 88.0%, negative predictive value (NPV) of 91.4% and accuracy of 90.0% in patients without previous RT, and a sensitivity of 97.1%, specificity of 83.3%, PPV of 94.3%, NPV of 90.9% and accuracy of 93.5% in those with previous neck RT. The ranges of the short-axis and long-axis length were 13.3 ± 8.0 mm (mean ± SD) versus 17.8 ± 9.1 mm, and 18.6 ± 9.0 mm versus 24.4 ± 10.9 mm for recurrent LNs from patients with, versus without, previous RT (both ps < 0.05), respectively. 76.5% (26/34) of the recurrent nodes after RT and 48% (12/25) of the recurrent nodes without previous RT exhibited an irregular margin (p < 0.05). Additionally, irradiated recurrent LNs had a significantly decreased percentage of discernable calcification compared with non-irradiated recurrent nodes (48% versus 20.6%, p < 0.05). Conclusions RT had influence on sonographic characteristics but no influence on USgFNA in diagnosing recurrent LNs in treated OSCC patients. PMID:26954569

  13. SU-E-J-47: Development of a High-Precision, Image-Guided Radiotherapy, Multi- Purpose Radiation Isocenter Quality-Assurance Calibration and Checking System

    SciTech Connect

    Liu, C; Yan, G; Helmig, R; Lebron, S; Kahler, D

    2014-06-01

    Purpose: To develop a system that can define the radiation isocenter and correlate this information with couch coordinates, laser alignment, optical distance indicator (ODI) settings, optical tracking system (OTS) calibrations, and mechanical isocenter walkout. Methods: Our team developed a multi-adapter, multi-purpose quality assurance (QA) and calibration device that uses an electronic portal imaging device (EPID) and in-house image-processing software to define the radiation isocenter, thereby allowing linear accelerator (Linac) components to be verified and calibrated. Motivated by the concept that each Linac component related to patient setup for image-guided radiotherapy based on cone-beam CT should be calibrated with respect to the radiation isocenter, we designed multiple concentric adapters of various materials and shapes to meet the needs of MV and KV radiation isocenter definition, laser alignment, and OTS calibration. The phantom's ability to accurately define the radiation isocenter was validated on 4 Elekta Linacs using a commercial ball bearing (BB) phantom as a reference. Radiation isocenter walkout and the accuracy of couch coordinates, ODI, and OTS were then quantified with the device. Results: The device was able to define the radiation isocenter within 0.3 mm. Radiation isocenter walkout was within ±1 mm at 4 cardinal angles. By switching adapters, we identified that the accuracy of the couch position digital readout, ODI, OTS, and mechanical isocenter walkout was within sub-mm. Conclusion: This multi-adapter, multi-purpose isocenter phantom can be used to accurately define the radiation isocenter and represents a potential paradigm shift in Linac QA. Moreover, multiple concentric adapters allowed for sub-mm accuracy for the other relevant components. This intuitive and user-friendly design is currently patent pending.

  14. Residual Seminal Vesicle Displacement in Marker-Based Image-Guided Radiotherapy for Prostate Cancer and the Impact on Margin Design

    SciTech Connect

    Smitsmans, Monique H.P.; Bois, Josien de; Sonke, Jan-Jakob; Catton, Charles N.; Jaffray, David A.; Lebesque, Joos V.; Herk, Marcel van

    2011-06-01

    Purpose: The objectives of this study were to quantify residual interfraction displacement of seminal vesicles (SV) and investigate the efficacy of rotation correction on SV displacement in marker-based prostate image-guided radiotherapy (IGRT). We also determined the effect of marker registration on the measured SV displacement and its impact on margin design. Methods and Materials: SV displacement was determined relative to marker registration by using 296 cone beam computed tomography scans of 13 prostate cancer patients with implanted markers. SV were individually registered in the transverse plane, based on gray-value information. The target registration error (TRE) for the SV due to marker registration inaccuracies was estimated. Correlations between prostate gland rotations and SV displacement and between individual SV displacements were determined. Results: The SV registration success rate was 99%. Displacement amounts of both SVs were comparable. Systematic and random residual SV displacements were 1.6 mm and 2.0 mm in the left-right direction, respectively, and 2.8 mm and 3.1 mm in the anteroposterior (AP) direction, respectively. Rotation correction did not reduce residual SV displacement. Prostate gland rotation around the left-right axis correlated with SV AP displacement (R{sup 2} = 42%); a correlation existed between both SVs for AP displacement (R{sup 2} = 62%); considerable correlation existed between random errors of SV displacement and TRE (R{sup 2} = 34%). Conclusions: Considerable residual SV displacement exists in marker-based IGRT. Rotation correction barely reduced SV displacement, rather, a larger SV displacement was shown relative to the prostate gland that was not captured by the marker position. Marker registration error partly explains SV displacement when correcting for rotations. Correcting for rotations, therefore, is not advisable when SV are part of the target volume. Margin design for SVs should take these uncertainties into

  15. Multi-beam laser altimeter

    NASA Technical Reports Server (NTRS)

    Bufton, Jack L.; Harding, David J.; Ramos-Izquierdo, Luis

    1993-01-01

    Laser altimetry provides a high-resolution, high-accuracy method for measurement of the elevation and horizontal variability of Earth-surface topography. The basis of the measurement is the timing of the round-trip propagation of short-duration pulses of laser radiation between a spacecraft and the Earth's surface. Vertical resolution of the altimetry measurement is determined primarily by laser pulsewidth, surface-induced spreading in time of the reflected pulse, and the timing precision of the altimeter electronics. With conventional gain-switched pulses from solid-state lasers and sub-nsec resolution electronics, sub-meter vertical range resolution is possible from orbital attitudes of several hundred kilometers. Horizontal resolution is a function of laser beam footprint size at the surface and the spacing between successive laser pulses. Laser divergence angle and altimeter platform height above the surface determine the laser footprint size at the surface, while laser pulse repetition-rate, laser transmitter beam configuration, and altimeter platform velocity determine the space between successive laser pulses. Multiple laser transitters in a singlaltimeter instrument provide across-track and along-track coverage that can be used to construct a range image of the Earth's surface. Other aspects of the multi-beam laser altimeter are discussed.

  16. SU-E-J-12: An Image-Guided Soft Robotic Patient Positioning System for Maskless Head-And-Neck Cancer Radiotherapy: A Proof-Of-Concept Study

    SciTech Connect

    Ogunmolu, O; Gans, N; Jiang, S; Gu, X

    2015-06-15

    Purpose: We propose a surface-image-guided soft robotic patient positioning system for maskless head-and-neck radiotherapy. The ultimate goal of this project is to utilize a soft robot to realize non-rigid patient positioning and real-time motion compensation. In this proof-of-concept study, we design a position-based visual servoing control system for an air-bladder-based soft robot and investigate its performance in controlling the flexion/extension cranial motion on a mannequin head phantom. Methods: The current system consists of Microsoft Kinect depth camera, an inflatable air bladder (IAB), pressured air source, pneumatic valve actuators, custom-built current regulators, and a National Instruments myRIO microcontroller. The performance of the designed system was evaluated on a mannequin head, with a ball joint fixed below its neck to simulate torso-induced head motion along flexion/extension direction. The IAB is placed beneath the mannequin head. The Kinect camera captures images of the mannequin head, extracts the face, and measures the position of the head relative to the camera. This distance is sent to the myRIO, which runs control algorithms and sends actuation commands to the valves, inflating and deflating the IAB to induce head motion. Results: For a step input, i.e. regulation of the head to a constant displacement, the maximum error was a 6% overshoot, which the system then reduces to 0% steady-state error. In this initial investigation, the settling time to reach the regulated position was approximately 8 seconds, with 2 seconds of delay between the command start of motion due to capacitance of the pneumatics, for a total of 10 seconds to regulate the error. Conclusion: The surface image-guided soft robotic patient positioning system can achieve accurate mannequin head flexion/extension motion. Given this promising initial Result, the extension of the current one-dimensional soft robot control to multiple IABs for non-rigid positioning control

  17. Dosimetric implications of residual seminal vesicle motion in fiducial-guided intensity-modulated radiotherapy for prostate cancer

    SciTech Connect

    Stenmark, Matthew H.; Vineberg, Karen; Ten Haken, Randall K.; Hamstra, Daniel A.; Feng, Mary

    2012-10-01

    To determine whether residual interfraction seminal vesicle (SV) displacement necessitates specific planning target volume (PTV) margins during fiducial-guided intensity modulated radiation therapy (IMRT) of the prostate. A planning computed tomography (CT) scan and 2 subsequent CT scans were prospectively obtained for 20 prostate cancer patients with intraprostatic fiducial markers. After CT registration, SV displacement relative to the prostate was quantified as a function of margin size for both the proximal (1 cm) SV (PSV) and the full SV (FSV). Two IMRT plans were simulated for each patient (prostate + PSV and prostate + FSV) both with a uniform 5-mm PTV margin. Minimum clinical target volume (CTV) dose (D{sub min}) and the volume of SV receiving 95% of the prescription dose (V{sub 95%}) were assessed during treatment and compared with the initial plan. In all cases, SV displacement with respect to the prostate was greater for the FSV compared with the PSV. To ensure at least 95% geometrical coverage of the CTV for 90% of patients, margins of 5 and 8 mm were required for the PSV and FSV, respectively. Dosimetrically, residual SV displacement had minimal impact on PSV coverage compared with FSV coverage. For the PSV D{sub min} was {>=}95% of the prescribed dose in 90% of patients with an overall mean V{sub 95%} of 99.6 {+-} 0.8%; for the FSV D{sub min} was {>=}95% of the prescribed dose in only 45% of patients with a mean V{sub 95%} of 97.9 {+-} 2.4%. The SVs move differentially from the prostate and exhibit greater variation with increasing distance from the prostate. For plans targeting just the prostate and PSVs, 5-mm PTV expansions are adequate. However, despite daily localization of the prostate, larger PTV margins are required for cases where the intent is to completely cover the FSV.

  18. Polymeric micelles as a diagnostic tool for image-guided drug delivery and radiotherapy of HER2 overexpressing breast cancer

    NASA Astrophysics Data System (ADS)

    Hoang, Nu Bryan

    Block copolymer micelles have emerged as a viable formulation strategy with several drugs relying on this technology in clinical evaluation. To date, information on the tumor penetration and intratumoral distribution of block copolymer micelles (BCM) has been quite limited. Thus, there is impetus to develop a radiolabeled formulation that can be used to gain invaluable insight into the intratumoral distribution of the BCMs. This information could then be used to direct formulation strategies as a means to optimize treatment outcomes. This thesis describes the synthesis and characterization of a targeted block copolymer micelle system based on poly(ethylene glycol)-block -poly(epsilon-caprolactone) labeled with the radionuclide Indium-111 (111In). The incorporation of the imageable component, 111In permits pursuit of image-guided drug delivery for real-time monitoring of tumor localization and intratumoral distribution. Intracellular trafficking of drugs and therapies such as Auger electron emitting radionuclides to perinuclear and nuclear regions of cells is critical to realizing their full therapeutic potential. HER2 specific antibodies (trastuzumab fab fragments) and nuclear localization signal peptides were conjugated to the surface of the BCMs to direct uptake in HER2 expressing cells and subsequent localization in the cell nucleus. Cell uptake was HER2 density dependent, confirming receptor-mediated internalization of the BCMs. Importantly, conjugation of NLS resulted in a significant increase in nuclear uptake of the radionuclide 111In. Successful nuclear targeting was shown to improve the antiproliferative effect of the Auger electrons. In addition, a significant radiation enhancement effect was observed by concurrent delivery of low-dose MTX and 111In in all breast cancer cell lines evaluated. Imaging enabled the accurate quantification of the specific tumor uptake of the micelles and visualization of their degree of tumor penetration in relation to

  19. [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

  20. Systematic Endobronchial Ultrasound-guided Mediastinal Staging Versus Positron Emission Tomography for Comprehensive Mediastinal Staging in NSCLC Before Radical Radiotherapy of Non-small Cell Lung Cancer: A Pilot Study.

    PubMed

    Steinfort, Daniel P; Siva, Shankar; Leong, Tracy L; Rose, Morgan; Herath, Dishan; Antippa, Phillip; Ball, David L; Irving, Louis B

    2016-02-01

    Despite known limitations of positron emission tomography (PET) for mediastinal staging of non-small cell lung cancer (NSCLC), radiation treatment fields are generally based on PET-identified disease extent. However, no studies have examined the accuracy of FDG-PET/CT on a per-node basis in patients being considered for curative-intent radiotherapy in NSCLC.In a prospective trial, patients with NSCLC being considered for definitive thoracic radiotherapy (± systemic chemotherapy) underwent minimally invasive systematic mediastinal evaluation with endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) following noninvasive staging with integrated PET-CT.Thirty patients underwent EBUS-TBNA, with TBNA performed from a mean 2.5 lymph node (LN) stations per patient (median 3, range 1-5). Discordant findings between PET-CT and EBUS-TBNA were observed in 10 patients (33%, 95% CI 19%-51%). PET-occult LN metastases were demonstrated by EBUS in 4 patients, whereas a lesser extent of mediastinal involvement, compared with FDG-PET, was demonstrated by EBUS in 6 patients, including 2 patients downstaged from cN3 to pN2. LNs upstaged by EBUS were significantly smaller than nodes downstaged by EBUS, 7.5 mm (range 7-9) versus 12 mm (range 6-21), P = 0.005.A significant proportion of patients considered for definitive radiotherapy (+/-chemotherapy) undergoing systematic mediastinal evaluation with EBUS-TBNA in this study have an extent of mediastinal NSCLC involvement discordant with that indicated by PET-CT. Systematic EBUS-TBNA may aid in defining the extent of mediastinal involvement in NSCLC patients undergoing radiotherapy. Systematic EBUS-TBNA has the potential to contribute significantly to radiotherapy planning and delivery, by either identifying occult nodal metastases, or demonstrating FDG-avid LNs to be disease-free. PMID:26937894

  1. Setup Variations in Radiotherapy of Anal Cancer: Advantages of Target Volume Reduction Using Image-Guided Radiation Treatment

    SciTech Connect

    Chen Yijen; Suh, Steve; Nelson, Rebecca A.; Liu An; Pezner, Richard D.; Wong, Jeffrey Y.C.

    2012-09-01

    Purpose: To define setup variations in the radiation treatment (RT) of anal cancer and to report the advantages of image-guided RT (IGRT) in terms of reduction of target volume and treatment-related side effects. Methods and Materials: Twelve consecutive patients with anal cancer treated by combined chemoradiation by use of helical tomotherapy from March 2007 to November 2008 were selected. With patients immobilized and positioned in place, megavoltage computed tomography (MVCT) scans were performed before each treatment and were automatically registered to planning CT scans. Patients were shifted per the registration data and treated. A total of 365 MVCT scans were analyzed. The primary site received a median dose of 55 Gy. To evaluate the potential dosimetric advantage(s) of IGRT, cases were replanned according to Radiation Therapy Oncology Group 0529, with and without adding recommended setup variations from the current study. Results: Significant setup variations were observed throughout the course of RT. The standard deviations for systematic setup correction in the anterior-posterior (AP), lateral, and superior-inferior (SI) directions and roll rotation were 1.1, 3.6, and 3.2 mm, and 0.3 Degree-Sign , respectively. The average random setup variations were 3.8, 5.5, and 2.9 mm, and 0.5 Degree-Sign , respectively. Without daily IGRT, margins of 4.9, 11.1, and 8.5 mm in the AP, lateral, and SI directions would have been needed to ensure that the planning target volume (PTV) received {>=}95% of the prescribed dose. Conversely, daily IGRT required no extra margins on PTV and resulted in a significant reduction of V15 and V45 of intestine and V10 of pelvic bone marrow. Favorable toxicities were observed, except for acute hematologic toxicity. Conclusions: Daily MVCT scans before each treatment can effectively detect setup variations and thereby reduce PTV margins in the treatment of anal cancer. The use of concurrent chemotherapy and IGRT provided favorable

  2. [Radiotherapy for brain metastases].

    PubMed

    Latorzeff, I; Antoni, D; Gaudaire-Josset, S; Feuvret, L; Tallet-Richard, A; Truc, G; Noël, G

    2016-09-01

    Radiotherapy for brain metastases has become more multifaceted. Indeed, with the improvement of the patient's life expectancy, side effects must be undeniably avoided and the retreatments or multiple treatments are common. The cognitive side effects should be warned and the most modern techniques of radiation therapy are used regularly to reach this goal. The new classifications of patients with brain metastases help guiding treatment more appropriately. Stereotactic radiotherapy has supplanted whole brain radiation therapy both for patients with metastases in place and for those who underwent surgery. Hippocampus protection is possible with intensity-modulated radiotherapy. Its relevance in terms of cognitive functioning should be more clearly demonstrated but the requirement, for using it, is increasingly strong. While addressing patients in palliative phase, the treatment of brain metastases is one of the localisations where technical thinking is the most challenging. PMID:27523410

  3. High Retention and Safety of Percutaneously Implanted Endovascular Embolization Coils as Fiducial Markers for Image-Guided Stereotactic Ablative Radiotherapy of Pulmonary Tumors

    SciTech Connect

    Hong, Julian C.; Yu Yao; Rao, Aarti K.; Dieterich, Sonja; Maxim, Peter G.; Le, Quynh-Thu; Diehn, Maximilian; Sze, Daniel Y.; Kothary, Nishita; Loo, Billy W.

    2011-09-01

    Purpose: To compare the retention rates of two types of implanted fiducial markers for stereotactic ablative radiotherapy (SABR) of pulmonary tumors, smooth cylindrical gold 'seed' markers ('seeds') and platinum endovascular embolization coils ('coils'), and to compare the complication rates associated with the respective implantation procedures. Methods and Materials: We retrospectively analyzed the retention of percutaneously implanted markers in 54 consecutive patients between January 2004 and June 2009. A total of 270 markers (129 seeds, 141 coils) were implanted in or around 60 pulmonary tumors over 59 procedures. Markers were implanted using a percutaneous approach under computed tomography (CT) guidance. Postimplantation and follow-up imaging studies were analyzed to score marker retention relative to the number of markers implanted. Markers remaining near the tumor were scored as retained. Markers in a distant location (e.g., pleural space) were scored as lost. CT imaging artifacts near markers were quantified on radiation therapy planning scans. Results: Immediately after implantation, 140 of 141 coils (99.3%) were retained, compared to 110 of 129 seeds (85.3%); the difference was highly significant (p < 0.0001). Of the total number of lost markers, 45% were reported lost during implantation, but 55% were lost immediately afterwards. No additional markers were lost on longer-term follow-up. Implanted lesions were peripherally located for both seeds (mean distance, 0.33 cm from pleural surface) and coils (0.34 cm) (p = 0.96). Incidences of all pneumothorax (including asymptomatic) and pneumothorax requiring chest tube placement were lower in implantation of coils (23% and 3%, respectively) vs. seeds (54% and 29%, respectively; p = 0.02 and 0.01). The degree of CT artifact was similar between marker types. Conclusions: Retention of CT-guided percutaneously implanted coils is significantly better than that of seed markers. Furthermore, implanting coils is at

  4. Adaptive Image-Guided Radiotherapy (IGRT) Eliminates the Risk of Biochemical Failure Caused by the Bias of Rectal Distension in Prostate Cancer Treatment Planning: Clinical Evidence

    SciTech Connect

    Park, Sean S.; Yan Di; McGrath, Samuel; Dilworth, Joshua T.; Liang Jian; Ye Hong; Krauss, Daniel J.; Martinez, Alvaro A.; Kestin, Larry L.

    2012-07-01

    Purpose: Rectal distension has been shown to decrease the probability of biochemical control. Adaptive image-guided radiotherapy (IGRT) corrects for target position and volume variations, reducing the risk of biochemical failure while yielding acceptable rates of gastrointestinal (GI)/genitourinary (GU) toxicities. Methods and Materials: Between 1998 and 2006, 962 patients were treated with computed tomography (CT)-based offline adaptive IGRT. Patients were stratified into low (n = 400) vs. intermediate/high (n = 562) National Comprehensive Cancer Network (NCCN) risk groups. Target motion was assessed with daily CT during the first week. Electronic portal imaging device (EPID) was used to measure daily setup error. Patient-specific confidence-limited planning target volumes (cl-PTV) were then constructed, reducing the standard PTV and compensating for geometric variation of the target and setup errors. Rectal volume (RV), cross-sectional area (CSA), and rectal volume from the seminal vesicles to the inferior prostate (SVP) were assessed on the planning CT. The impact of these volumetric parameters on 5-year biochemical control (BC) and chronic Grades {>=}2 and 3 GU and GI toxicity were examined. Results: Median follow-up was 5.5 years. Median minimum dose covering cl-PTV was 75.6 Gy. Median values for RV, CSA, and SVP were 82.8 cm{sup 3}, 5.6 cm{sup 2}, and 53.3 cm{sup 3}, respectively. The 5-year BC was 89% for the entire group: 96% for low risk and 83% for intermediate/high risk (p < 0.001). No statistically significant differences in BC were seen with stratification by RV, CSA, and SVP in quartiles. Maximum chronic Grades {>=}2 and 3 GI toxicities were 21.2% and 2.9%, respectively. Respective values for GU toxicities were 15.5% and 4.3%. No differences in GI or GU toxicities were noted when patients were stratified by RV. Conclusions: Incorporation of adaptive IGRT reduces the risk of geometric miss and results in excellent biochemical control that is

  5. 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

  6. Evaluation of Juvenile Salmon Behavior at Bonneville Dam, Columbia River, Using a Multibeam Technique

    SciTech Connect

    Johnson, Robert L. ); Moursund, Russell A. )

    1999-11-01

    In recent years, with increased effort to bypass and guide fragile stocks of juvenile salmon in the Columbia Basin past hydroelectric projects, it has been increasingly important to obtain fine-scale fish behavior data in a non-intrusive manner. The Dual-Head Multibeam Sonar is an emerging technology for fisheries applications that addresses that requirement. It has two principal advantages over traditional hydroacoustic techniques: (1) it allows for simultaneous large-volume coverage of a region of interest, and (2) it affords 3-D tracking capability. The use of Dual-Head Multibeam Sonar in this study resulted in unprecedented insight into fine-scale smolt behavior upstream of a prototype surface collector at Bonneville Dam first powerhouse in 1998. Our results indicated that outmigrant juvenile salmon had an increased likelihood of milling or holding. This discovery will lead to better design criteria for future bypass and collector systems. Future fisheries multibeam sonar systems will likely be fully integrated systems with built-in real time tracking capability. These systems may be used to track targets relative to physical guidance structures or other behavior modifying stimuli such as light, turbulent flow, electrical/magnetic fields, or low-frequency sound and vibration. The combination of fine-scale fish behavior data and environmental parameters will yield better design criteria for the safe passage of listed or endangered species of Pacific salmon.

  7. Multibeam synthetic aperture radar for global oceanography

    NASA Technical Reports Server (NTRS)

    Jain, A.

    1979-01-01

    A single-frequency multibeam synthetic aperture radar concept for large swath imaging desired for global oceanography is evaluated. Each beam iilluminates a separate range and azimuth interval, and images for different beams may be separated on the basis of the Doppler spectrum of the beams or their spatial azimuth separation in the image plane of the radar processor. The azimuth resolution of the radar system is selected so that the Doppler spectrum of each beam does not interfere with the Doppler foldover due to the finite pulse repetition frequency of the radar system.

  8. Current advances in radiotherapy of head and neck malignancies.

    PubMed

    Roopashri, G; Baig, Muqeet

    2013-12-01

    Necessity is the mother of all inventions. This is also true in case of cancer therapy. With increasing incidence of head and neck malignancies, remarkable developments have been made towards cancer development and treatment which continues to be a major challenge. Approximately fifty percent of all cancer patients receive radiotherapy which contributes towards forty percent of curative treatment for cancer. New developments in radiation oncology have helped to improve outlook for patients and find more effective treatment. With the advent of new technologies, radiotherapy seems to be promising in patients with head and neck malignancies these advancements include Altered fractionation, Three-dimensional conformal radiotherapy, Intensity-modulated radiotherapy, Image Guided Radiotherapy, Stereotactic radiation, Charged-particle radiotherapy, and Intraoperative radiotherapy. How to cite this article: Roopashri G, Baig M. Current advances in radiotherapy of head and neck malignancies. J Int Oral Health 2013; 5(6):119-23 . PMID:24453456

  9. Theoretical and experimental research on multi-beam klystron

    SciTech Connect

    Ding Yaogen; Peng Jun; Zhu Yunshu; Shi Shaoming

    1999-05-07

    Theoretical and experimental research work on multi-beam klystron (MBK) conducted in Institute of Electronics, Chinese Academy of Sciences (IECAS) is described in this paper. Research progress on Interaction between multi-electron beam and microwave electric field, multi-beam cavity, filter loaded double gap cavity broadband output circuit, multi-beam electron gun, and periodic reversal focusing system is presented. Performance and measurement results of five types of MBK are also given out. The key technical problems for present MBK are discussed in this paper.

  10. Quantification of a multibeam sonar for fisheries assessment applications.

    PubMed

    Cochrane, N A; Li, Y; Melvin, G D

    2003-08-01

    The acoustic theory is developed for a multibeam fisheries-type sonar employing a circular arc of transducer elements. Specifically, numerical relations for transmit and receive beam patterns are derived and methodologies set forth for the derivation of appropriately scaled acoustic target strength and acoustic volume backscattering strength from an ideally performing multibeam device. Predicted and measured beam characteristics of a realizable multibeam sonar, a Kongsberg Simrad-Mesotech SM 2000, are compared. Practical techniques for the extraction of calibrated acoustic volume backscattering strength from real systems are advanced. PMID:12942957

  11. 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

  12. Positron Emission Tomography/Computed Tomography-Guided Intensity-Modulated Radiotherapy for Limited-Stage Small-Cell Lung Cancer

    SciTech Connect

    Shirvani, Shervin M.; Komaki, Ritsuko; Heymach, John V.; Fossella, Frank V.

    2012-01-01

    Purpose: Omitting elective nodal irradiation from planning target volumes does not compromise outcomes in patients with non-small-cell lung cancer, but whether the same is true for those with limited-stage small-cell lung cancer (LS-SCLC) is unknown. Therefore, in the present study, we sought to determine the clinical outcomes and the frequency of elective nodal failure in patients with LS-SCLC staged using positron emission tomography/computed tomography and treated with involved-field intensity-modulated radiotherapy. Methods and Materials: Between 2005 and 2008, 60 patients with LS-SCLC at our institution underwent disease staging using positron emission tomography/computed tomography before treatment using an intensity-modulated radiotherapy plan in which elective nodal irradiation was intentionally omitted from the planning target volume (mode and median dose, 45 Gy in 30 fractions; range, 40.5 Gy in 27 fractions to 63.8 Gy in 35 fractions). In most cases, concurrent platinum-based chemotherapy was administered. We retrospectively reviewed the clinical outcomes to determine the overall survival, relapse-free survival, and failure patterns. Elective nodal failure was defined as recurrence in initially uninvolved hilar, mediastinal, or supraclavicular nodes. Survival was assessed using the Kaplan-Meier method. Results: The median age of the study patients at diagnosis was 63 years (range, 39-86). The median follow-up duration was 21 months (range, 4-58) in all patients and 26 months (range, 4-58) in the survivors. The 2-year actuarial overall survival and relapse-free survival rate were 58% and 43%, respectively. Of the 30 patients with recurrence, 23 had metastatic disease and 7 had locoregional failure. We observed only one isolated elective nodal failure. Conclusions: To our knowledge, this is the first study to examine the outcomes in patients with LS-SCLC staged with positron emission tomography/computed tomography and treated with definitive intensity

  13. Protocol for a phase III randomised trial of image-guided intensity modulated radiotherapy (IG-IMRT) and conventional radiotherapy for late small bowel toxicity reduction after postoperative adjuvant radiation in Ca cervix

    PubMed Central

    Chopra, Supriya; Engineer, Reena; Mahantshetty, Umesh; Misra, Shagun; Phurailatpam, Reena; Paul, Siji N; Kannan, Sadhna; Kerkar, Rajendra; Maheshwari, Amita; Shylasree, TS; Ghosh, Jaya; Gupta, Sudeep; Thomas, Biji; Singh, Shalini; Sharma, Sanjiv; Chilikuri, Srinivas; Shrivastava, Shyam Kishore

    2012-01-01

    Introduction External beam radiation followed by vaginal brachytherapy (±chemotherapy) leads to reduction in the risk of local recurrence and improves progression-free survival in patients with adverse risk factors following Wertheim's hysterectomy albeit at the risk of late bowel toxicity. Intensity Modulated Radiotherapy (IMRT) results in reduction in bowel doses and has potential to reduce late morbidity, however, needs to be confirmed prospectively in a randomised trial. The present randomised trial tests reduction if any in late small bowel toxicity with the use of IMRT in postoperative setting. Methods and analysis Patients more than 18 years of age who need adjuvant (chemo) radiation will be eligible. Patients with residual pelvic or para-aortic nodal disease, history of multiple abdominal surgeries or any other medical bowel condition will be excluded. The trial will randomise patients into standard radiation or IMRT. The primary aim is to compare differences in late grades II–IV bowel toxicity between the two arms. The secondary aims of the study focus on evaluating correlation of dose–volume parameters and late toxicity and quality of life. The trial is planned as a multicentre randomised study. The trial is designed to detect a 13% difference in late grades II–IV bowel toxicity with an α of 0.05 and β of 0.80. A total of 240 patients will be required to demonstrate the aforesaid difference. Ethics and dissemination The trial is approved by institutional ethics review board and will be routinely monitored as per standard guidelines. The study results will be disseminated via peer reviewed scientific journals, conference presentations and submission to regulatory authorities. Registration The trial is registered with clinicaltrials.gov (NCT 01279135). PMID:23242243

  14. SU-C-18A-04: 3D Markerless Registration of Lung Based On Coherent Point Drift: Application in Image Guided Radiotherapy

    SciTech Connect

    Nasehi Tehrani, J; Wang, J; Guo, X; Yang, Y

    2014-06-01

    Purpose: This study evaluated a new probabilistic non-rigid registration method called coherent point drift for real time 3D markerless registration of the lung motion during radiotherapy. Method: 4DCT image datasets Dir-lab (www.dir-lab.com) have been used for creating 3D boundary element model of the lungs. For the first step, the 3D surface of the lungs in respiration phases T0 and T50 were segmented and divided into a finite number of linear triangular elements. Each triangle is a two dimensional object which has three vertices (each vertex has three degree of freedom). One of the main features of the lungs motion is velocity coherence so the vertices that creating the mesh of the lungs should also have features and degree of freedom of lung structure. This means that the vertices close to each other tend to move coherently. In the next step, we implemented a probabilistic non-rigid registration method called coherent point drift to calculate nonlinear displacement of vertices between different expiratory phases. Results: The method has been applied to images of 10-patients in Dir-lab dataset. The normal distribution of vertices to the origin for each expiratory stage were calculated. The results shows that the maximum error of registration between different expiratory phases is less than 0.4 mm (0.38 SI, 0.33 mm AP, 0.29 mm RL direction). This method is a reliable method for calculating the vector of displacement, and the degrees of freedom (DOFs) of lung structure in radiotherapy. Conclusions: We evaluated a new 3D registration method for distribution set of vertices inside lungs mesh. In this technique, lungs motion considering velocity coherence are inserted as a penalty in regularization function. The results indicate that high registration accuracy is achievable with CPD. This method is helpful for calculating of displacement vector and analyzing possible physiological and anatomical changes during treatment.

  15. SU-E-CAMPUS-J-04: Image Guided Radiation Therapy (IGRT): Review of Technical Standards and Credentialing in Radiotherapy Clinical Trials

    SciTech Connect

    Giaddui, T; Chen, W; Yu, J; Gong, Y; Galvin, J; Xiao, Y; Cui, Y; Yin, F; Craig, T; Dawson, L; Al-Hallaq, H; Chmura, S

    2014-06-15

    Purpose: To review IGRT credentialing experience and unexpected technical issues encountered in connection with advanced radiotherapy technologies as implemented in RTOG clinical trials. To update IGRT credentialing procedures with the aim of improving the quality of the process, and to increase the proportion of IGRT credentialing compliance. To develop a living disease site-specific IGRT encyclopedia. Methods: Numerous technical issues were encountered during the IGRT credentialing process. The criteria used for credentialing review were based on: image quality; anatomy included in fused data sets and shift results. Credentialing requirements have been updated according to the AAPM task group reports for IGRT to ensure that all required technical items are included in the quality review process. Implementation instructions have been updated and expanded for recent protocols. Results: Technical issues observed during the credentialing review process include, but are not limited to: poor quality images; inadequate image acquisition region; poor data quality; shifts larger than acceptable; no soft tissue surrogate. The updated IGRT credentialing process will address these issues and will also include the technical items required from AAPM: TG 104; TG 142 and TG 179 reports. An instruction manual has been developed describing a remote credentialing method for reviewers. Submission requirements are updated, including images/documents as well as facility questionnaire. The review report now includes summary of the review process and the parameters that reviewers check. We have reached consensus on the minimum IGRT technical requirement for a number of disease sites. RTOG 1311(NRG-BR002A Phase 1 Study of Stereotactic Body Radiotherapy (SBRT) for the Treatment of Multiple Metastases) is an example, here; the protocol specified the minimum requirement for each anatomical sites (with/without fiducials). Conclusion: Technical issues are identified and reported. IGRT

  16. Minimal Inter-Fractional Fiducial Migration during Image-Guided Lung Stereotactic Body Radiotherapy Using SuperLock Nitinol Coil Fiducial Markers

    PubMed Central

    Rong, Yi; Bazan, Jose G.; Sekhon, Ashley; Haglund, Karl; Xu-Welliver, Meng; Williams, Terence

    2015-01-01

    Objectives Stereotactic body radiotherapy (SBRT) is being increasingly used for the treatment of patients with lung cancer or lung metastasis who are medically unfit to undergo resection. In order to improve accuracy and confidence in targeting tumors, many centers rely on fiducial implantation. We evaluated the migration of a novel fiducial marker specifically designed for lung tissue implanted via electromagnetic navigation bronchoscopy (ENB). Methods We retrospectively quantified the individual and group migrations of SuperLock nitinol coil fiducials for 15 patients receiving lung stereotactic body radiotherapy (SBRT), in order to evaluate the reliability of using these fiducials as a target surrogate for cases where tumors cannot be clearly delineated on cone beam CTs (CBCTs). For each fraction, we compared the individual and group migrations of the fiducials between the planning CT and the acquired CBCT. The group migration was defined as the distance between the centroids of the fiducial group and GTV. Results A total of 16 lung targets were included in our study for these 15 patients (one patient with two targets). Of 55 fiducials placed, we observed a 100% retention rate. The mean individual migration was 1.87 mm (range, 0.63–5.25 mm) with a standard deviation of 1.26 mm. The mean group migration was 1.94 mm (range, 0.03–6.19 mm) with a standard deviation of 1.45 mm. Overall, there was minimal change in the relative locations of the markers with respect to each other, as well as to the target. Conclusions We found that the SuperLock nitinol coil fiducial marker positions are stable throughout the radiation treatment, and can be used as a reliable surrogate to target, and to avoid geometric misses during gated treatments. PMID:26158847

  17. Noise limitations on monopulse accuracy in a multibeam antenna

    NASA Astrophysics Data System (ADS)

    Loraine, J.; Wallington, J. R.

    A multibeam system allowing target tracking using monopulse processing switched from beamset to beamset is considered. Attention is given to the accuracy of target angular position estimation. An analytical method is used to establish performance limits under low SNR conditions for a multibeam system. It is shown that, in order to achieve accuracies comparable to those of conventional monopulse systems, much higher SNRs are needed.

  18. [Postoperative radiotherapy of prostate cancer].

    PubMed

    Guérif, S; Latorzeff, I; Lagrange, J-L; Hennequin, C; Supiot, S; Garcia, A; François, P; Soulié, M; Richaud, P; Salomon, L

    2014-10-01

    Between 10 and 40% of patients who have undergone a radical prostatectomy may have a biologic recurrence. Local or distant failure represents the possible patterns of relapse. Patients at high-risk for local relapse have extraprostatic disease, positive surgical margins or seminal vesicles infiltration or high Gleason score at pathology. Three phase-III randomized clinical trials have shown that, for these patients, adjuvant irradiation reduces the risk of tumoral progression without higher toxicity. Salvage radiotherapy for late relapse allows a disease control in 60-70% of the cases. Several research in order to improve the therapeutic ratio of the radiotherapy after prostatectomy are evaluate in the French Groupe d'Étude des Tumeurs Urogénitales (Gétug) and of the French association of urology (Afu). The Gétug-Afu 17 trial will provide answers to the question of the optimal moment for postoperative radiotherapy for pT3-4 R1 pN0 Nx patients, with the objective of comparing an immediate treatment to a differed early treatment initiated at biological recurrence. The Gétug-Afu 22 questions the place of a short hormonetherapy combined with image-guided, intensity-modulated radiotherapy (IMRT) in adjuvant situation for a detectable prostate specific antigen (PSA). The implementation of a multicenter quality control within the Gétug-Afu in order to harmonize a modern postoperative radiotherapy will allow the development of a dose escalation IMRT after surgery. PMID:25195116

  19. ETS-VI multibeam satellite communications systems

    NASA Astrophysics Data System (ADS)

    Kawai, Makoto; Tanaka, Masayoshi; Ohtomo, Isao

    1989-10-01

    The fixed and mobile satellite communications systems of the Japanese Engineering Test Satellite-VI (ETS-VI) are described. The system requirements are outlined along with the system configuration. The ETS-VI multibeam system employs three frequency bands. When used for Ka-band fixed communications, it covers the Japanese main islands with thirteen 0.3-degree-wide spot beam. Four of the beams are active for ETS-VI. When used for S-band mobile communications, five beams cover the area within 200 nautical miles from the Japanese coast. The C-band beam for fixed communications covers the central area of the Japanese main islands with a single beam. The onboard antenna system is described along with the transponders and their associated onboard systems. A discussion of the system technology follows, covering the TDMA transmisssion system, the relay function, rainfall compensation, and the antenna and propagation performance.

  20. An analysis of the multibeam altimeter

    NASA Astrophysics Data System (ADS)

    Bush, G. B.; Dobson, E. B.; Matyskiela, R.; Kilgus, C. C.; Walsh, E. J.

    The design concept and computer simulations of a multibeam altimeter (MA) to provide satellite-based oceanographic-feature data for map construction within relatively short times are presented. The limitations of the pulse-limited radar altimeter used on GEOS-3 and SEASAT-A, in particular the narrow swath of each measurement pass, are characterized. The MA uses interferometry with two 1.2-m dish antennas separated by an 11-m boom to cover a total swath width of 100 km at satellite altitude 800 km, nominal repetition rate 6 kp/sec, and nominal integration time 2.5 sec. Simulation analysis of antenna element pattern, echo shape, tracking algorithms, tracking noise, and measurement accuracy was performed, and the general feasibility of ocean-current mapping with a one-week time delay, using two MA-equipped satellites, was demonstrated.

  1. Parametric constraints in multi-beam interference

    NASA Astrophysics Data System (ADS)

    Burrow, Guy M.; Gaylord, Thomas K.

    2012-10-01

    Multi-beam interference (MBI) represents a method of producing one-, two-, and three-dimensional submicron periodic optical-intensity distributions for applications including micro- and nano-electronics, photonic crystals, metamaterial, biomedical structures, optical trapping, and numerous other subwavelength structures. Accordingly, numerous optical configurations have been developed to implement MBI. However, these configurations typically provide limited ability to condition the key parameters of each interfering beam. Constraints on individual beam amplitudes and polarizations are systematically considered to understand their effects on lithographically useful MBI periodic patterning possibilities. A method for analyzing parametric constraints is presented and used to compare the optimized optical-intensity distributions for representative constrained systems. Case studies are presented for both square and hexagonal-lattices produced via three-beam interference. Results demonstrate that constraints on individual-beam polarizations significantly impact patterning possibilities and must be included in the systematic design of an MBI system.

  2. Multi-beam linear accelerator EVT

    NASA Astrophysics Data System (ADS)

    Teryaev, Vladimir E.; Kazakov, Sergey Yu.; Hirshfield, Jay L.

    2016-09-01

    A novel electron multi-beam accelerator is presented. The accelerator, short-named EVT (Electron Voltage Transformer) belongs to the class of two-beam accelerators. It combines an RF generator and essentially an accelerator within the same vacuum envelope. Drive beam-lets and an accelerated beam are modulated in RF modulators and then bunches pass into an accelerating structure, comprising uncoupled with each other and inductive tuned cavities, where the energy transfer from the drive beams to the accelerated beam occurs. A phasing of bunches is solved by choice correspond distances between gaps of the adjacent cavities. Preliminary results of numerical simulations and the initial specification of EVT operating in S-band, with a 60 kV gun and generating a 2.7 A, 1.1 MV beam at its output is presented. A relatively high efficiency of 67% and high design average power suggest that EVT can find its use in industrial applications.

  3. SU-E-J-55: End-To-End Effectiveness Analysis of 3D Surface Image Guided Voluntary Breath-Holding Radiotherapy for Left Breast

    SciTech Connect

    Lin, M; Feigenberg, S

    2015-06-15

    Purpose To evaluate the effectiveness of using 3D-surface-image to guide breath-holding (BH) left-side breast treatment. Methods Two 3D surface image guided BH procedures were implemented and evaluated: normal-BH, taking BH at a comfortable level, and deep-inspiration-breath-holding (DIBH). A total of 20 patients (10 Normal-BH and 10 DIBH) were recruited. Patients received a BH evaluation using a commercialized 3D-surface- tracking-system (VisionRT, London, UK) to quantify the reproducibility of BH positions prior to CT scan. Tangential 3D/IMRT plans were conducted. Patients were initially setup under free-breathing (FB) condition using the FB surface obtained from the untaged CT to ensure a correct patient position. Patients were then guided to reach the planned BH position using the BH surface obtained from the BH CT. Action-levels were set at each phase of treatment process based on the information provided by the 3D-surface-tracking-system for proper interventions (eliminate/re-setup/ re-coaching). We reviewed the frequency of interventions to evaluate its effectiveness. The FB-CBCT and port-film were utilized to evaluate the accuracy of 3D-surface-guided setups. Results 25% of BH candidates with BH positioning uncertainty > 2mm are eliminated prior to CT scan. For >90% of fractions, based on the setup deltas from3D-surface-trackingsystem, adjustments of patient setup are needed after the initial-setup using laser. 3D-surface-guided-setup accuracy is comparable as CBCT. For the BH guidance, frequency of interventions (a re-coaching/re-setup) is 40%(Normal-BH)/91%(DIBH) of treatments for the first 5-fractions and then drops to 16%(Normal-BH)/46%(DIBH). The necessity of re-setup is highly patient-specific for Normal-BH but highly random among patients for DIBH. Overall, a −0.8±2.4 mm accuracy of the anterior pericardial shadow position was achieved. Conclusion 3D-surface-image technology provides effective intervention to the treatment process and ensures

  4. 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.

  5. Tungsten Sulfide Quantum Dots as Multifunctional Nanotheranostics for In Vivo Dual-Modal Image-Guided Photothermal/Radiotherapy Synergistic Therapy.

    PubMed

    Yong, Yuan; Cheng, Xiaju; Bao, Tao; Zu, Mian; Yan, Liang; Yin, Wenyan; Ge, Cuicui; Wang, Dongliang; Gu, Zhanjun; Zhao, Yuliang

    2015-12-22

    Designing a multifunctional nanomedicine for integration of precise diagnosis and effective treatment of tumors is desirable but remains a great challenge. Here, we report a multifunctional nanomedicine based on WS2 quantum dots (QDs), which was prepared by a facile and "green" method through physical grinding and ultrasonication. The as-obtained WS2 QDs with small size (3 nm) possess not only significant X-ray computed tomography (CT)/photoaccoustic (PA) imaging signal enhancement but also remarkable photothermal therapy (PTT)/radiotherapy (RT) synergistic effect for tumor treatment. With CT/PA imaging and the synergistic effect between PTT and RT, the tumor could be accurately positioned and thoroughly eradicated in vivo after intravenous injection of WS2 QDs. Moreover, hematoxylin and eosin staining, blood hematology, and biochemistry analysis revealed no noticeable toxicity of WS2 QDs in vitro and in vivo, which confirmed that WS2 QDs possess good biocompatibility. This multifunctional nanoparticle could play an important role in facilitating simultaneously multimodal imaging and synergistic therapy between PTT and RT to achieve better therapeutic efficacy. PMID:26495962

  6. Is a Clinical Target Volume (CTV) Necessary in the Treatment of Lung Cancer in the Modern Era Combining 4-D Imaging and Image-guided Radiotherapy (IGRT)?

    PubMed Central

    Kilburn, Jeremy M; Lucas, John T; Soike, Michael H; Ayala-Peacock, Diandra N; Blackstock, Arthur W; Hinson, William H; Munley, Michael T; Petty, William J

    2016-01-01

    Objective: We hypothesized that omission of clinical target volumes (CTV) in lung cancer radiotherapy would not compromise control by determining retrospectively if the addition of a CTV would encompass the site of failure. Methods: Stage II-III patients were treated from 2009-2012 with daily cone-beam imaging and a 5 mm planning target volume (PTV) without a CTV. PTVs were expanded 1 cm and termed CTVretro. Recurrences were scored as 1) within the PTV, 2) within CTVretro, or 3) outside the PTV. Locoregional control (LRC), distant control (DC), progression-free survival (PFS), and overall survival (OS) were estimated. Result: Among 110 patients, Stage IIIA 57%, IIIB 32%, IIA 4%, and IIB 7%. Eighty-six percent of Stage III patients received chemotherapy. Median dose was 70 Gy (45-74 Gy) and fraction size ranged from 1.5-2.7 Gy. Median follow-up was 12 months, median OS was 22 months (95% CI 19-30 months), and LRC at two years was 69%. Fourteen local and eight regional events were scored with two CTVretro failures equating to a two-year CTV failure-free survival of 98%. Conclusion: Omission of a 1 cm CTV expansion appears feasible based on only two events among 110 patients and should be considered in radiation planning. PMID:26929893

  7. 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

  8. Auv Multibeam Bathymetry and Sidescan Survey of the SS Montebello wreck Offshore Cambria CA

    NASA Astrophysics Data System (ADS)

    Caress, D. W.; Thomas, H.; Conlin, D.; Thompson, D.; Paull, C. K.

    2010-12-01

    An MBARI Mapping AUV survey of the SS Montebello wreck offshore Cambria, CA collected high-resolution multibeam bathymetry and sidescan imagery of the vessel and the surrounding seafloor. The Montebello was an oil tanker that was torpedoed and sunk about 11 km offshore in 275 m water depth by a Japanese submarine on December 23, 1941. The Montebello was loaded with 3,000,000 gallons of crude oil, and there is no evidence that significant leakage of that cargo occurred at the time of the sinking or in the 69 years since. The California Department of Fish and Game’s Office of Spill Prevention and Response (OSPR) commissioned the AUV survey as part of a multi-agency Montebello Task Force effort to assess the potential pollution threat. The survey data will be used to determine the extent and general character of the wreckage for a pending Task Force report and to guide any future ROV dive or assessment activity . The AUV surveyed the wreck site from altitudes of 75 and 25 m; the low-altitude high-resolution survey consists of a grid with a 50 m line spacing both parallel and orthogonal to the ship. The 200 kHz multibeam bathymetry images the wreck from both above and from the sides with an 0.5 m lateral resolution. The combination of soundings from all of the survey lines results in a three-dimensional distribution of soundings that delineates the external morphology and some of the internal structure of the wreck. 410 kHz chirp sidescan sonar data also image the site from both directions. The bathymetry data indicate that the Montebello was pitched forward down when it impacted the bottom, crushing and breaking off the bow section. Both forward and aft deckhouses are largely intact, and in fact the multibeam images the individual decks within those structures. About half of the forward mast remains, both amidships masts and the smokestack are missing. A good deal of the deck piping and equipment appears intact, and aside from the bow, the ship’s sides appear

  9. Image-guided intensity-modulated radiotherapy for refractory bilateral breast cancer in a patient with extensive cutaneous metastasis in the chest and abdominal walls

    PubMed Central

    Lu, Yueh-Feng; Lin, Yu-Chin; Chen, Kuo-Hsin; Shueng, Pei-Wei; Yeh, Hsin-Pei; Hsieh, Chen-Hsi

    2016-01-01

    Treatment for bilateral breast cancer with chest wall and abdominal skin invasion normally involves conventional radiotherapy (RT); however, conventional RT provides inadequate target volume coverage and excessive treatment of large volumes of normal tissue. Helical tomotherapy (HT) has the ability to deliver continuous craniocaudal irradiation that suppresses junction problems and provides good conformity of dose distribution. A 47-year-old female with stage IV bilateral breast cancer with chest wall and pectoralis major muscle invasion, lymphadenopathy, bilateral pleural effusion, and multiple bone metastases received chemotherapy and target therapy beginning in January 2014; 4 months after the initiation of chemotherapy, computed tomography revealed progression of chest and abdominal wall invasion. A total dose of 70.2 Gy was delivered to both breasts, the chest wall, the abdominal wall, and the bilateral supraclavicular nodal areas in 39 fractions via HT. The total planning target volume was 4,533.29 cm3. The percent of lung volume receiving at least 20 Gy (V20) was 28%, 22%, and 25% for the right lung, left lung, and whole lung, respectively. The mean dose to the heart was 8.6 Gy. Follow-up computed tomography revealed complete response after the RT course. Grade 1 dysphagia, weight loss, grade 2 neutropenia, and grade 3 dermatitis were noted during the RT course. Pain score decreased from 6 to 1. No cardiac, pulmonary, liver, or intestinal toxicity developed during treatment or follow-up. Concurrent HT with or without systemic treatment could be a safe salvage therapy for chemorefractory locally advanced breast cancer patients with extensive cutaneous metastasis. PMID:27284253

  10. FIRE: an open-software suite for real-time 2D/3D image registration for image guided radiotherapy research

    NASA Astrophysics Data System (ADS)

    Furtado, H.; Gendrin, C.; Spoerk, J.; Steiner, E.; Underwood, T.; Kuenzler, T.; Georg, D.; Birkfellner, W.

    2016-03-01

    Radiotherapy treatments have changed at a tremendously rapid pace. Dose delivered to the tumor has escalated while organs at risk (OARs) are better spared. The impact of moving tumors during dose delivery has become higher due to very steep dose gradients. Intra-fractional tumor motion has to be managed adequately to reduce errors in dose delivery. For tumors with large motion such as tumors in the lung, tracking is an approach that can reduce position uncertainty. Tumor tracking approaches range from purely image intensity based techniques to motion estimation based on surrogate tracking. Research efforts are often based on custom designed software platforms which take too much time and effort to develop. To address this challenge we have developed an open software platform especially focusing on tumor motion management. FLIRT is a freely available open-source software platform. The core method for tumor tracking is purely intensity based 2D/3D registration. The platform is written in C++ using the Qt framework for the user interface. The performance critical methods are implemented on the graphics processor using the CUDA extension. One registration can be as fast as 90ms (11Hz). This is suitable to track tumors moving due to respiration (~0.3Hz) or heartbeat (~1Hz). Apart from focusing on high performance, the platform is designed to be flexible and easy to use. Current use cases range from tracking feasibility studies, patient positioning and method validation. Such a framework has the potential of enabling the research community to rapidly perform patient studies or try new methods.

  11. Real-time intensity based 2D/3D registration using kV-MV image pairs for tumor motion tracking in image guided radiotherapy

    NASA Astrophysics Data System (ADS)

    Furtado, H.; Steiner, E.; Stock, M.; Georg, D.; Birkfellner, W.

    2014-03-01

    Intra-fractional respiratorymotion during radiotherapy is one of themain sources of uncertainty in dose application creating the need to extend themargins of the planning target volume (PTV). Real-time tumormotion tracking by 2D/3D registration using on-board kilo-voltage (kV) imaging can lead to a reduction of the PTV. One limitation of this technique when using one projection image, is the inability to resolve motion along the imaging beam axis. We present a retrospective patient study to investigate the impact of paired portal mega-voltage (MV) and kV images, on registration accuracy. We used data from eighteen patients suffering from non small cell lung cancer undergoing regular treatment at our center. For each patient we acquired a planning CT and sequences of kV and MV images during treatment. Our evaluation consisted of comparing the accuracy of motion tracking in 6 degrees-of-freedom(DOF) using the anterior-posterior (AP) kV sequence or the sequence of kV-MV image pairs. We use graphics processing unit rendering for real-time performance. Motion along cranial-caudal direction could accurately be extracted when using only the kV sequence but in AP direction we obtained large errors. When using kV-MV pairs, the average error was reduced from 3.3 mm to 1.8 mm and the motion along AP was successfully extracted. The mean registration time was of 190+/-35ms. Our evaluation shows that using kVMV image pairs leads to improved motion extraction in 6 DOF. Therefore, this approach is suitable for accurate, real-time tumor motion tracking with a conventional LINAC.

  12. Evaluation of overall setup accuracy and adequate setup margins in pelvic image-guided radiotherapy: Comparison of the male and female patients

    SciTech Connect

    Laaksomaa, Marko; Kapanen, Mika; Tulijoki, Tapio; Peltola, Seppo; Hyödynmaa, Simo; Kellokumpu-Lehtinen, Pirkko-Liisa

    2014-04-01

    We evaluated adequate setup margins for the radiotherapy (RT) of pelvic tumors based on overall position errors of bony landmarks. We also estimated the difference in setup accuracy between the male and female patients. Finally, we compared the patient rotation for 2 immobilization devices. The study cohort included consecutive 64 male and 64 female patients. Altogether, 1794 orthogonal setup images were analyzed. Observer-related deviation in image matching and the effect of patient rotation were explicitly determined. Overall systematic and random errors were calculated in 3 orthogonal directions. Anisotropic setup margins were evaluated based on residual errors after weekly image guidance. The van Herk formula was used to calculate the margins. Overall, 100 patients were immobilized with a house-made device. The patient rotation was compared against 28 patients immobilized with CIVCO's Kneefix and Feetfix. We found that the usually applied isotropic setup margin of 8 mm covered all the uncertainties related to patient setup for most RT treatments of the pelvis. However, margins of even 10.3 mm were needed for the female patients with very large pelvic target volumes centered either in the symphysis or in the sacrum containing both of these structures. This was because the effect of rotation (p ≤ 0.02) and the observer variation in image matching (p ≤ 0.04) were significantly larger for the female patients than for the male patients. Even with daily image guidance, the required margins remained larger for the women. Patient rotations were largest about the lateral axes. The difference between the required margins was only 1 mm for the 2 immobilization devices. The largest component of overall systematic position error came from patient rotation. This emphasizes the need for rotation correction. Overall, larger position errors and setup margins were observed for the female patients with pelvic cancer than for the male patients.

  13. A Method to Estimate Mean Position, Motion Magnitude, Motion Correlation, and Trajectory of a Tumor From Cone-Beam CT Projections for Image-Guided Radiotherapy

    SciTech Connect

    Poulsen, Per Rugaard Cho, Byungchul; Keall, Paul J.

    2008-12-01

    Purpose: To develop a probability-based method for estimating the mean position, motion magnitude, and trajectory of a tumor using cone-beam CT (CBCT) projections. Method and Materials: CBCT acquisition was simulated for more than 80 hours of patient-measured trajectories for thoracic/abdominal tumors and prostate. The trajectories were divided into 60-second segments for which CBCT was simulated by projecting the tumor position onto a rotating imager. Tumor (surrogate) visibility on all projections was assumed. The mean and standard deviation of the tumor position and motion correlation along the three axes were determined with maximum likelihood estimation based on the projection data, assuming a Gaussian spatial distribution. The unknown position component along the imager axis was approximated by its expectation value, determined by the Gaussian distribution. Transformation of the resulting three-dimensional position to patient coordinates provided the estimated trajectory. Two trajectories were experimentally investigated by CBCT acquisition of a phantom. Results: The root-mean-square error of the estimated mean position was 0.05 mm. The root-mean-square error of the trajectories was <1 mm in 99.1% of the thorax/abdomen cases and in 99.7% of the prostate cases. The experimental trajectory estimation agreed with the actual phantom trajectory within 0.44 mm in any direction. Clinical applicability was demonstrated by estimating the tumor trajectory for a pancreas cancer case. Conclusions: A method for estimation of mean position, motion magnitude, and trajectory of a tumor from CBCT projections has been developed. The accuracy was typically much better than 1 mm. The method is applicable to motion-inclusive, respiratory-gated, and tumor-tracking radiotherapy.

  14. Comparison of Localization Performance with Implanted Fiducial Markers and Cone-Beam Computed Tomography for On-line Image-Guided Radiotherapy of the Prostate

    PubMed Central

    Moseley, Douglas J; White, Elizabeth A; Wiltshire, Kirsty L; Rosewall, Tara; Sharpe, Michael B; Siewerdsen, Jeffrey H; Bissonnette, Jean-Pierre; Gospodarowicz, Mary; Warde, Padraig; Catton, Charles N; Jaffray, David A

    2007-01-01

    Purpose To assess the accuracy of kV cone-beam CT (CBCT) based setup corrections as compared to orthogonal MV portal image-based corrections for patients undergoing external-beam radiotherapy of the prostate. Method and Materials Daily cone-beam CT volumetric images were acquired after setup for patients with three intra-prostatic fiducial markers. The estimated couch shifts were compared retrospectively to patient adjustments based on two orthogonal MV portal images (the current clinical standard of care in our institution). The CBCT soft-tissue based shifts were also estimated by digitally removing the gold markers in each projection to suppress the artifacts in the reconstructed volumes. A total of 256 volumetric images for 15 patients were analyzed. Results The Pearson coefficient of correlation for the patient position shifts using fiducial markers in MV vs kV was (R2 = 0.95, 0.84, 0.81) in the L/R, A/P and S/I directions respectively. The correlation using soft-tissue matching was ((R2 = 0.90, 0.49, 0.51) in the L/R, A/P and S/I directions. A Bland-Altman analysis showed no significant trends in the data. The percentage of shifts within a +/−3mm tolerance (the clinical action level) was (99.7, 95.5, 91.3) for fiducial marker matching and (99.5, 70.3, 78.4) for soft-tissue matching. Conclusions Cone-beam CT is an accurate and precise tool for image-guidance. It provides an equivalent means of patient setup correction for prostate patients with implanted gold fiducial markers. Use of the additional information provided by the visualization of soft-tissue structures is an active area of research. PMID:17293243

  15. Radiotherapy planning using MRI

    NASA Astrophysics Data System (ADS)

    Schmidt, Maria A.; Payne, Geoffrey S.

    2015-11-01

    The use of magnetic resonance imaging (MRI) in radiotherapy (RT) planning is rapidly expanding. We review the wide range of image contrast mechanisms available to MRI and the way they are exploited for RT planning. However a number of challenges are also considered: the requirements that MR images are acquired in the RT treatment position, that they are geometrically accurate, that effects of patient motion during the scan are minimized, that tissue markers are clearly demonstrated, that an estimate of electron density can be obtained. These issues are discussed in detail, prior to the consideration of a number of specific clinical applications. This is followed by a brief discussion on the development of real-time MRI-guided RT.

  16. Seafloor Characterisation and Imaging Using Multibeam Sonar Data

    NASA Astrophysics Data System (ADS)

    Łubniewski, Zbigniew; Bruniecki, Krzysztof

    The approach to seafloor characterisation and imaging is presented. It relies on the combined, concurrent use of several techniques of multibeam sonar data processing. The first one is based on constructing the grey-level sonar images of seabed using the backscattering strength calculated for the echoes received in the consecutive beams. Then, the set of parameters describing the local region of sonar image is calculated. The second technique utilises the 3D model of the seabed surface, which is constructed as a set of (x, y, z) points using the detected bottom range for each beam in the multibeam system seafloor imaging procedure. For the local region of seabed surface, the descriptors like rms height and autocorrelation slope are calculated. The third technique assumes the use of a set of parameters of the multibeam echo envelope. Then, for selected parameters, the characteristic features quantitatively describing their dependence on seafloor incident angle, like slope, or range, are calculated. Finally, the features obtained by these three techniques are combined together. The proposed method has been tested using multibeam data records acquired from several bottom types in the Gulf of Gdańsk region. The obtained preliminary results show that application of the proposed combined approach improves the classification performance in comparison with those of using only the one scheme of seafloor multibeam data processing.

  17. SU-E-J-219: Quantitative Evaluation of Motion Effects On Accuracy of Image-Guided Radiotherapy with Fiducial Markers Using CT Imaging

    SciTech Connect

    Ali, I; Oyewale, S; Ahmad, S; Algan, O; Alsbou, N

    2014-06-01

    Purpose: To investigate quantitatively patient motion effects on the localization accuracy of image-guided radiation with fiducial markers using axial CT (ACT), helical CT (HCT) and cone-beam CT (CBCT) using modeling and experimental phantom studies. Methods: Markers with different lengths (2.5 mm, 5 mm, 10 mm, and 20 mm) were inserted in a mobile thorax phantom which was imaged using ACT, HCT and CBCT. The phantom moved with sinusoidal motion with amplitudes ranging 0–20 mm and a frequency of 15 cycles-per-minute. Three parameters that include: apparent marker lengths, center position and distance between the centers of the markers were measured in the different CT images of the mobile phantom. A motion mathematical model was derived to predict the variations in the previous three parameters and their dependence on the motion in the different imaging modalities. Results: In CBCT, the measured marker lengths increased linearly with increase in motion amplitude. For example, the apparent length of the 10 mm marker was about 20 mm when phantom moved with amplitude of 5 mm. Although the markers have elongated, the center position and the distance between markers remained at the same position for different motion amplitudes in CBCT. These parameters were not affected by motion frequency and phase in CBCT. In HCT and ACT, the measured marker length, center and distance between markers varied irregularly with motion parameters. The apparent lengths of the markers varied with inverse of the phantom velocity which depends on motion frequency and phase. Similarly the center position and distance between markers varied inversely with phantom speed. Conclusion: Motion may lead to variations in maker length, center position and distance between markers using CT imaging. These effects should be considered in patient setup using image-guided radiation therapy based on fiducial markers matching using 2D-radiographs or volumetric CT imaging.

  18. 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

  19. A Phase II prospective nonrandomized trial of magnetic resonance imaging-guided hematopoietic bone marrow-sparing radiotherapy for gastric cancer patients with concurrent chemotherapy

    PubMed Central

    Wang, Jianyang; Tian, Yuan; Tang, Yuan; Wang, Xin; Li, Ning; Ren, Hua; Fang, Hui; Feng, Yanru; Wang, Shulian; Song, Yongwen; Liu, Yueping; Wang, Weihu; Li, Yexiong; Jin, Jing

    2016-01-01

    Purpose This study aimed to spare hematopoietical bone marrow (BM) identified by magnetic resonance (MR) radiation in order to alleviate acute hematologic toxicity (HT) for gastric cancer patients treated with postoperative chemoradiotherapy (CRT). Methods A prospective, open-label, single-arm Phase II study (Clinicaltrials.gov; NCT 01863420) was conducted in 25 patients with gastric cancer who were eligible for postoperative concurrent CRT. The MR images of vertebral body T8-L4 were fused with images of simulating computed tomography. Hematopoietical BM was contoured according to the MR and spared in radiotherapy plan. The CRT regimen consisted of daily capecitabine (1600 mg/m2/d) and 45 Gy of radiation at 1.8 Gy per day. Primary endpoints were grade ≥3 HT that occurred within 2 months of initiation of CRT. The relationship between HT and dose–volume of BM was estimated by multivariable linear regression model. Results Twenty four patients (96%) had T3–4 disease and 22 (88%) had disease with node positive. The median age was 53 years (range, 28–73 years). Before concurrent CRT, adjuvant chemotherapy was administered with a mean cycle of 4.3±0.5. Only five patients (20%) developed grade 3–4 HT during treatment, among whom two (8.0%) patients experienced grade 3–4 leucopenia, two (8.0%) experienced neutropenia, and two (8.0%) experienced thrombocytopenia, respectively. None of the patients showed grade 3–4 anemia. Multivariable linear regression revealed increased BM-V5 (P=0.03) and BM-V20 (P=0.002) were found to be significantly associated with decreased white blood cells nadirs in multivariable regression; increased BM-V20 (P<0.001) with decreased absolute neutrophil count nadirs, increased BM-V30 (P=0.002) and volume of BM (P=0.001) with decreased platelet count nadirs. Conclusion Irradiation of active BM identified by MR is associated with HTs. Techniques to limit low-dose radiation, especially V20, to BM could reduce HT in gastric cancer patients

  20. ACTS Multibeam Antenna On-Orbit Performance

    NASA Technical Reports Server (NTRS)

    Acosta, R.; Wright, D.; Mitchell, Kenneth

    1996-01-01

    The Advanced Communications Technology Satellite (ACTS) launched in September 1993 introduces several new technologies including a multibeam antenna (MBA) operating at Ka-band. The MBA with fixed and rapidly reconfigurable spot beams serves users equipped with small aperture terminals within the coverage area. The antenna produces spot beams with approximately 0.3 degrees beamwidth and gains of approximately 50 dBi. A number of MBA performance evaluations have been performed since the ACTS launch. These evaluations were designed to assess MBA performance (e.g., beam pointing stability, beam shape, gain, etc.) in the space environment. The on-orbit measurements found systematic environmental perturbation to the MBA beam pointing. These perturbations were found to be imposed by satellite attitude control system, antenna and spacecraft mechanical alignments, on-orbit thermal effects, etc. As a result, the footprint coverage of the MBA may not exactly cover the intended service area at all times. This report describes the space environment effects on the ACTS MBA performance as a function of time of the day and time of the year and compensation approaches for these effects.

  1. SU-E-J-44: A Novel Approach to Quantify Patient Setup and Target Motion for Real-Time Image-Guided Radiotherapy (IGRT)

    SciTech Connect

    Li, S; Charpentier, P; Sayler, E; Micaily, B; Miyamoto, C; Geng, J

    2015-06-15

    Purpose Isocenter shifts and rotations to correct patient setup errors and organ motion cannot remedy some shape changes of large targets. We are investigating new methods in quantification of target deformation for realtime IGRT of breast and chest wall cancer. Methods Ninety-five patients of breast or chest wall cancer were accrued in an IRB-approved clinical trial of IGRT using 3D surface images acquired at daily setup and beam-on time via an in-room camera. Shifts and rotations relating to the planned reference surface were determined using iterative-closest-point alignment. Local surface displacements and target deformation are measured via a ray-surface intersection and principal component analysis (PCA) of external surface, respectively. Isocenter shift, upper-abdominal displacement, and vectors of the surface projected onto the two principal components, PC1 and PC2, were evaluated for sensitivity and accuracy in detection of target deformation. Setup errors for some deformed targets were estimated by superlatively registering target volume, inner surface, or external surface in weekly CBCT or these outlines on weekly EPI. Results Setup difference according to the inner-surface, external surface, or target volume could be 1.5 cm. Video surface-guided setup agreed with EPI results to within < 0.5 cm while CBCT results were sometimes (∼20%) different from that of EPI (>0.5 cm) due to target deformation for some large breasts and some chest walls undergoing deep-breath-hold irradiation. Square root of PC1 and PC2 is very sensitive to external surface deformation and irregular breathing. Conclusion PCA of external surfaces is quick and simple way to detect target deformation in IGRT of breast and chest wall cancer. Setup corrections based on the target volume, inner surface, and external surface could be significant different. Thus, checking of target shape changes is essential for accurate image-guided patient setup and motion tracking of large deformable

  2. 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.

  3. Inelastic x-ray scattering from phonons under multibeam conditions

    NASA Astrophysics Data System (ADS)

    Bosak, Alexey; Krisch, Michael

    2007-03-01

    We report on an experimental observation of a previously neglected multibeam contribution to the inelastic x-ray scattering cross section. Its manifestation is a substantial modification of the apparent phonon selection rules when two (or more) reciprocal lattice points are simultaneously intercepted by the Ewald sphere. The observed multibeam contributions can be treated semi-quantitatively in the frame of Renninger’s “simplest approach.” A few corollaries, relevant for experimental work on inelastic scattering from phonons, are presented.

  4. 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

  5. Contour propagation in MRI-guided radiotherapy treatment of cervical cancer: the accuracy of rigid, non-rigid and semi-automatic registrations

    NASA Astrophysics Data System (ADS)

    van der Put, R. W.; Kerkhof, E. M.; Raaymakers, B. W.; Jürgenliemk-Schulz, I. M.; Lagendijk, J. J. W.

    2009-12-01

    External beam radiation treatment for patients with cervical cancer is hindered by the relatively large motion of the target volume. A hybrid MRI-accelerator system makes it possible to acquire online MR images during treatment in order to correct for motion and deformation. To fully benefit from such a system, online delineation of the target volumes is necessary. The aim of this study is to investigate the accuracy of rigid, non-rigid and semi-automatic registrations of MR images for interfractional contour propagation in patients with cervical cancer. Registration using mutual information was performed on both bony anatomy and soft tissue. A B-spline transform was used for the non-rigid method. Semi-automatic registration was implemented with a point set registration algorithm on a small set of manual landmarks. Online registration was simulated by application of each method to four weekly MRI scans for each of 33 cervical cancer patients. Evaluation was performed by distance analysis with respect to manual delineations. The results show that soft-tissue registration significantly (P < 0.001) improves the accuracy of contour propagation compared to registration based on bony anatomy. A combination of user-assisted and non-rigid registration provides the best results with a median error of 3.2 mm (1.4-9.9 mm) compared to 5.9 mm (1.7-19.7 mm) with bone registration (P < 0.001) and 3.4 mm (1.3-19.1 mm) with non-rigid registration (P = 0.01). In a clinical setting, the benefit may be further increased when outliers can be removed by visual inspection of the online images. We conclude that for external beam radiation treatment of cervical cancer, online MRI imaging will allow target localization based on soft tissue visualization, which provides a significantly higher accuracy than localization based on bony anatomy. The use of limited user input to guide the registration increases overall accuracy. Additional non-rigid registration further reduces the propagation

  6. NASA Adaptive Multibeam Phased Array (AMPA): An application study

    NASA Technical Reports Server (NTRS)

    Mittra, R.; Lee, S. W.; Gee, W.

    1982-01-01

    The proposed orbital geometry for the adaptive multibeam phased array (AMPA) communication system is reviewed and some of the system's capabilities and preliminary specifications are highlighted. Typical AMPA user link models and calculations are presented, the principal AMPA features are described, and the implementation of the system is demonstrated. System tradeoffs and requirements are discussed. Recommendations are included.

  7. Development of image quality assurance measures of the ExacTrac localization system using commercially available image evaluation software and hardware for image-guided radiotherapy.

    PubMed

    Stanley, Dennis N; Papanikolaou, Nikos; Gutiérrez, Alonso N

    2014-01-01

    Quality assurance (QA) of the image quality for image-guided localization systems is crucial to ensure accurate visualization and localization of target volumes. In this study, a methodology was developed to assess and evaluate the constancy of the high-contrast spatial resolution, dose, energy, contrast, and geometrical accuracy of the BrainLAB ExacTrac system. An in-house fixation device was constructed to hold the QCkV-1 phantom firmly and reproducibly against the face of the flat panel detectors. Two image sets per detector were acquired using ExacTrac preset console settings over a period of three months. The image sets were analyzed in PIPSpro and the following metrics were recorded: high-contrast spatial resolution (f30, f40, f50 (lp/mm)), noise, and contrast-to-noise ratio. Geometrical image accu- racy was evaluated by assessing the length between to predetermined points of the QCkV-1 phantom. Dose and kVp were recorded using the Unfors RaySafe Xi R/F Detector. The kVp and dose were evaluated for the following: Cranial Standard (CS) (80 kV,80 mA,80 ms), Thorax Standard (TS) (120 kV,160 mA,160 ms), Abdomen Standard (AS) (120 kV,160 mA,130 ms), and Pelvis Standard (PS) (120 kV,160 mA,160 ms). With regard to high-contrast spatial resolution, the mean values of the f30 (lp/mm), f40 (lp/mm) and f50 (lp/mm) for the left detector were 1.39 ± 0.04, 1.24 ± 0.05, and 1.09 ± 0.04, respectively, while for the right detector they were 1.38 ± 0.04, 1.22 ± 0.05, and 1.09 ± 0.05, respectively. Mean CNRs for the left and right detectors were 148 ± 3 and 143 ± 4, respectively. For geometrical accuracy, both detectors had a measured image length of the QCkV-1 of 57.9 ± 0.5 mm. The left detector showed dose measurements of 20.4 ± 0.2 μGy (CS), 191.8 ± 0.7 μGy (TS), 154.2 ± 0.7 μGy (AS), and 192.2 ± 0.6 μGy (PS), while the right detector showed 20.3 ± 0.3 μGy (CS), 189.7 ± 0.8 μGy (TS), 151.0 ± 0.7 μGy (AS), and 189.7 ± 0.8 μGy (PS), respectively. For X

  8. [Prophylactic axillary radiotherapy for breast cancer].

    PubMed

    Rivera, S; Louvel, G; Rivin Del Campo, E; Boros, A; Oueslati, H; Deutsch, É

    2015-06-01

    Adjuvant radiotherapy, after breast conserving surgery or mastectomy for breast cancer, improves overall survival while decreasing the risk of recurrence. However, prophylactic postoperative radiotherapy of locoregional lymph nodes for breast cancer, particularly of the axillary region, is still controversial since the benefits and the risks due to axillary irradiation have not been well defined. To begin with, when performing conformal radiotherapy, volume definition is crucial for the analysis of the risk-benefit balance of any radiation treatment. Definition and contouring of the axillary lymph node region is discussed in this work, as per the recommendations of the European Society for Radiotherapy and Oncology (ESTRO). Axillary recurrences are rare, and the recent trend leads toward less aggressive surgery with regard to the axilla. In this literature review we present the data that lead us to avoid adjuvant axillary radiotherapy in pN0, pN0i+ and pN1mi patients even without axillary clearance and to perform it in some other situations. Finally, we propose an update about the potential toxicity of adjuvant axillary irradiation, which is essential for therapeutic decision-making based on current evidence, and to guide us in the evolution of our techniques and indications of axillary radiotherapy. PMID:26044178

  9. Comparison of Shallow Survey 2012 Multibeam Datasets

    NASA Astrophysics Data System (ADS)

    Ramirez, T. M.

    2012-12-01

    The purpose of the Shallow Survey common dataset is a comparison of the different technologies utilized for data acquisition in the shallow survey marine environment. The common dataset consists of a series of surveys conducted over a common area of seabed using a variety of systems. It provides equipment manufacturers the opportunity to showcase their latest systems while giving hydrographic researchers and scientists a chance to test their latest algorithms on the dataset so that rigorous comparisons can be made. Five companies collected data for the Common Dataset in the Wellington Harbor area in New Zealand between May 2010 and May 2011; including Kongsberg, Reson, R2Sonic, GeoAcoustics, and Applied Acoustics. The Wellington harbor and surrounding coastal area was selected since it has a number of well-defined features, including the HMNZS South Seas and HMNZS Wellington wrecks, an armored seawall constructed of Tetrapods and Akmons, aquifers, wharves and marinas. The seabed inside the harbor basin is largely fine-grained sediment, with gravel and reefs around the coast. The area outside the harbor on the southern coast is an active environment, with moving sand and exposed reefs. A marine reserve is also in this area. For consistency between datasets, the coastal research vessel R/V Ikatere and crew were used for all surveys conducted for the common dataset. Using Triton's Perspective processing software multibeam datasets collected for the Shallow Survey were processed for detail analysis. Datasets from each sonar manufacturer were processed using the CUBE algorithm developed by the Center for Coastal and Ocean Mapping/Joint Hydrographic Center (CCOM/JHC). Each dataset was gridded at 0.5 and 1.0 meter resolutions for cross comparison and compliance with International Hydrographic Organization (IHO) requirements. Detailed comparisons were made of equipment specifications (transmit frequency, number of beams, beam width), data density, total uncertainty, and

  10. Status of Multi-beam Long Trace-profiler Development

    NASA Technical Reports Server (NTRS)

    Gubarev, Mikhail V.; Kilaru, Kiranmayee; Ramsey, Brian; McKinney, Wayne R.; Merthe, Daniel J.; Yashchuk, Valeriy V.; Takacs, Peter Z.

    2013-01-01

    The multi-beam long trace profiler (MB-LTP) is under development at NASA's Marshall Space Flight Center. The traditional LTPs scans the surface under the test by a single laser beam directly measuring the surface figure slope errors. While capable of exceptional surface slope accuracy, the LTP single beam scanning has slow measuring speed. Metrology efficiency can be increased by replacing the single laser beam with multiple beams that can scan a section of the test surface at a single instance. The increase in speed with such a system would be almost proportional to the number of laser beams. The progress for a multi-beam long trace profiler development will be presented.