Speedup of lexicographic optimization by superiorization and its applications to cancer radiotherapy treatment

NASA Astrophysics Data System (ADS)

Bonacker, Esther; Gibali, Aviv; Küfer, Karl-Heinz; Süss, Philipp

2017-04-01

Multicriteria optimization problems occur in many real life applications, for example in cancer radiotherapy treatment and in particular in intensity modulated radiation therapy (IMRT). In this work we focus on optimization problems with multiple objectives that are ranked according to their importance. We solve these problems numerically by combining lexicographic optimization with our recently proposed level set scheme, which yields a sequence of auxiliary convex feasibility problems; solved here via projection methods. The projection enables us to combine the newly introduced superiorization methodology with multicriteria optimization methods to speed up computation while guaranteeing convergence of the optimization. We demonstrate our scheme with a simple 2D academic example (used in the literature) and also present results from calculations on four real head neck cases in IMRT (Radiation Oncology of the Ludwig-Maximilians University, Munich, Germany) for two different choices of superiorization parameter sets suited to yield fast convergence for each case individually or robust behavior for all four cases.

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

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

Vogelius, Ivan S.; Department of Human Oncology, University of Wisconsin School of Medicine and Public Health, Madison, WI; Department of Radiation Oncology, Rigshospitalet

2011-07-01

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

Clinical experience with image-guided radiotherapy in an accelerated partial breast intensity-modulated radiotherapy protocol.

PubMed

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

2010-02-01

To explore the feasibility of fiducial markers for the use of image-guided radiotherapy (IGRT) in an accelerated partial breast intensity modulated radiotherapy protocol. 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. 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). 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. Copyright 2010 Elsevier Inc. All rights reserved.

Adjoint sensitivity analysis of a tumor growth model and its application to spatiotemporal radiotherapy optimization.

PubMed

Fujarewicz, Krzysztof; Lakomiec, Krzysztof

2016-12-01

We investigate a spatial model of growth of a tumor and its sensitivity to radiotherapy. It is assumed that the radiation dose may vary in time and space, like in intensity modulated radiotherapy (IMRT). The change of the final state of the tumor depends on local differences in the radiation dose and varies with the time and the place of these local changes. This leads to the concept of a tumor's spatiotemporal sensitivity to radiation, which is a function of time and space. We show how adjoint sensitivity analysis may be applied to calculate the spatiotemporal sensitivity of the finite difference scheme resulting from the partial differential equation describing the tumor growth. We demonstrate results of this approach to the tumor proliferation, invasion and response to radiotherapy (PIRT) model and we compare the accuracy and the computational effort of the method to the simple forward finite difference sensitivity analysis. Furthermore, we use the spatiotemporal sensitivity during the gradient-based optimization of the spatiotemporal radiation protocol and present results for different parameters of the model.

Patient-specific dosimetric endpoints based treatment plan quality control in radiotherapy.

PubMed

Song, Ting; Staub, David; Chen, Mingli; Lu, Weiguo; Tian, Zhen; Jia, Xun; Li, Yongbao; Zhou, Linghong; Jiang, Steve B; Gu, Xuejun

2015-11-07

In intensity modulated radiotherapy (IMRT), the optimal plan for each patient is specific due to unique patient anatomy. To achieve such a plan, patient-specific dosimetric goals reflecting each patient's unique anatomy should be defined and adopted in the treatment planning procedure for plan quality control. This study is to develop such a personalized treatment plan quality control tool by predicting patient-specific dosimetric endpoints (DEs). The incorporation of patient specific DEs is realized by a multi-OAR geometry-dosimetry model, capable of predicting optimal DEs based on the individual patient's geometry. The overall quality of a treatment plan is then judged with a numerical treatment plan quality indicator and characterized as optimal or suboptimal. Taking advantage of clinically available prostate volumetric modulated arc therapy (VMAT) treatment plans, we built and evaluated our proposed plan quality control tool. Using our developed tool, six of twenty evaluated plans were identified as sub-optimal plans. After plan re-optimization, these suboptimal plans achieved better OAR dose sparing without sacrificing the PTV coverage, and the dosimetric endpoints of the re-optimized plans agreed well with the model predicted values, which validate the predictability of the proposed tool. In conclusion, the developed tool is able to accurately predict optimally achievable DEs of multiple OARs, identify suboptimal plans, and guide plan optimization. It is a useful tool for achieving patient-specific treatment plan quality control.

Recent advances in intensity modulated radiotherapy and proton therapy for esophageal cancer.

PubMed

Xi, Mian; Lin, Steven H

2017-07-01

Radiotherapy is an important component of the standard of care for esophageal cancer. In the past decades, significant improvements in the planning and delivery of radiation techniques have led to better dose conformity to the target volume and improved normal tissue sparing. Areas covered: This review focuses on the advances in radiotherapy techniques and summarizes the availably dosimetric and clinical outcomes of intensity-modulated radiation therapy (IMRT), volumetric modulated arc therapy, proton therapy, and four-dimensional radiotherapy for esophageal cancer, and discusses the challenges and future development of proton therapy. Expert commentary: Although three-dimensional conformal radiotherapy is the standard radiotherapy technique in esophageal cancer, the retrospectively comparative studies strongly suggest that the dosimetric advantage of IMRT over three-dimensional conformal radiotherapy can translate into improved clinical outcomes, despite the lack of prospective randomized evidence. As a novel form of conventional IMRT technique, volumetric modulated arc therapy can produce equivalent or superior dosimetric quality with significantly higher treatment efficiency in esophageal cancer. Compared with photon therapy, proton therapy has the potential to achieve further clinical improvement due to their physical properties; however, prospective clinical data, long-term results, and cost-effectiveness are needed.

Simple Carotid-Sparing Intensity-Modulated Radiotherapy Technique and Preliminary Experience for T1-2 Glottic Cancer

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

Rosenthal, David I., E-mail: dirosenthal@mdanderson.or; Fuller, Clifton D.; Barker, Jerry L.

2010-06-01

Purpose: To investigate the dosimetry and feasibility of carotid-sparing intensity-modulated radiotherapy (IMRT) for early glottic cancer and to report preliminary clinical experience. Methods and Materials: Digital Imaging and Communications in Medicine radiotherapy (DICOM-RT) datasets from 6 T1-2 conventionally treated glottic cancer patients were used to create both conventional IMRT plans. We developed a simplified IMRT planning algorithm with three fields and limited segments. Conventional and IMRT plans were compared using generalized equivalent uniform dose and dose-volume parameters for in-field carotid arteries, target volumes, and organs at risk. We have treated 11 patients with this simplified IMRT technique. Results: Intensity-modulated radiotherapymore » consistently reduced radiation dose to the carotid arteries (p < 0.05) while maintaining the clinical target volume coverage. With conventional planning, median carotid V35, V50, and V63 were 100%, 100%, and 69.0%, respectively. With IMRT planning these decreased to 2%, 0%, and 0%, respectively (p < 0.01). Radiation planning and treatment times were similar for conventional radiotherapy and IMRT. Treatment results have been excellent thus far. Conclusions: Intensity-modulated radiotherapy significantly reduced unnecessary radiation dose to the carotid arteries compared with conventional lateral fields while maintaining clinical target volume coverage. Further experience and longer follow-up will be required to demonstrate outcomes for cancer control and carotid artery effects.« less

Vector-model-supported approach in prostate plan optimization

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

Liu, Eva Sau Fan; Department of Health Technology and Informatics, The Hong Kong Polytechnic University; Wu, Vincent Wing Cheung

Lengthy time consumed in traditional manual plan optimization can limit the use of step-and-shoot intensity-modulated radiotherapy/volumetric-modulated radiotherapy (S&S IMRT/VMAT). A vector model base, retrieving similar radiotherapy cases, was developed with respect to the structural and physiologic features extracted from the Digital Imaging and Communications in Medicine (DICOM) files. Planning parameters were retrieved from the selected similar reference case and applied to the test case to bypass the gradual adjustment of planning parameters. Therefore, the planning time spent on the traditional trial-and-error manual optimization approach in the beginning of optimization could be reduced. Each S&S IMRT/VMAT prostate reference database comprised 100more » previously treated cases. Prostate cases were replanned with both traditional optimization and vector-model-supported optimization based on the oncologists' clinical dose prescriptions. A total of 360 plans, which consisted of 30 cases of S&S IMRT, 30 cases of 1-arc VMAT, and 30 cases of 2-arc VMAT plans including first optimization and final optimization with/without vector-model-supported optimization, were compared using the 2-sided t-test and paired Wilcoxon signed rank test, with a significance level of 0.05 and a false discovery rate of less than 0.05. For S&S IMRT, 1-arc VMAT, and 2-arc VMAT prostate plans, there was a significant reduction in the planning time and iteration with vector-model-supported optimization by almost 50%. When the first optimization plans were compared, 2-arc VMAT prostate plans had better plan quality than 1-arc VMAT plans. The volume receiving 35 Gy in the femoral head for 2-arc VMAT plans was reduced with the vector-model-supported optimization compared with the traditional manual optimization approach. Otherwise, the quality of plans from both approaches was comparable. Vector-model-supported optimization was shown to offer much shortened planning time and iteration number without compromising the plan quality.« less

Dosimetric Factors Associated With Long-Term Dysphagia After Definitive Radiotherapy for Squamous Cell Carcinoma of the Head and Neck

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

Caudell, Jimmy J.; Schaner, Philip E.; Desmond, Renee A.

2010-02-01

Purpose: Intensification of radiotherapy and chemotherapy for head-and-neck cancer may lead to increased rates of dysphagia. Dosimetric predictors of objective findings of long-term dysphagia were sought. Methods and Materials: From an institutional database, 83 patients were identified who underwent definitive intensity-modulated radiotherapy for squamous cell carcinoma of the head and neck, after exclusion of those who were treated for a second or recurrent head-and-neck primary lesion, had locoregional recurrence at any time, had less than 12 months of follow-up, or had postoperative radiotherapy. Dosimetric parameters were analyzed relative to three objective endpoints as a surrogate for severe long-term dysphagia: percutaneousmore » endoscopic gastrostomy (PEG) tube dependence at 12 months, aspiration on modified barium swallow, or pharyngoesophageal stricture requiring dilation. Results: Mean dose greater than 41 Gy and volume receiving 60 Gy (V{sub 60}) greater than 24% to the larynx were significantly associated with PEG tube dependence and aspiration. V{sub 60} greater than 12% to the inferior pharyngeal constrictor was also significantly associated with increased PEG tube dependence and aspiration. V{sub 65} greater than 33% to the superior pharyngeal constrictor or greater than 75% to the middle pharyngeal constrictor was associated with pharyngoesophageal stricture requiring dilation. Conclusions: Doses to the larynx and pharyngeal constrictors predicted long-term swallowing complications, even when controlled for other clinical factors. The addition of these structures to intensity-modulated radiotherapy optimization may reduce the incidence of dysphagia, although cautious clinical validation is necessary.« less

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

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

Chen, Allen M., E-mail: allen.chen@ucdmc.ucdavis.edu; Farwell, D. Gregory; Luu, Quang

2011-07-01

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

Intensity modulated neutron radiotherapy optimization by photon proxy

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

Snyder, Michael; Hammoud, Ahmad; Bossenberger, Todd

2012-08-15

Purpose: Introducing intensity modulation into neutron radiotherapy (IMNRT) planning has the potential to mitigate some normal tissue complications seen in past neutron trials. While the hardware to deliver IMNRT plans has been in use for several years, until recently the IMNRT planning process has been cumbersome and of lower fidelity than conventional photon plans. Our in-house planning system used to calculate neutron therapy plans allows beam weight optimization of forward planned segments, but does not provide inverse optimization capabilities. Commercial treatment planning systems provide inverse optimization capabilities, but currently cannot model our neutron beam. Methods: We have developed a methodologymore » and software suite to make use of the robust optimization in our commercial planning system while still using our in-house planning system to calculate final neutron dose distributions. Optimized multileaf collimator (MLC) leaf positions for segments designed in the commercial system using a 4 MV photon proxy beam are translated into static neutron ports that can be represented within our in-house treatment planning system. The true neutron dose distribution is calculated in the in-house system and then exported back through the MATLAB software into the commercial treatment planning system for evaluation. Results: The planning process produces optimized IMNRT plans that reduce dose to normal tissue structures as compared to 3D conformal plans using static MLC apertures. The process involves standard planning techniques using a commercially available treatment planning system, and is not significantly more complex than conventional IMRT planning. Using a photon proxy in a commercial optimization algorithm produces IMNRT plans that are more conformal than those previously designed at our center and take much less time to create. Conclusions: The planning process presented here allows for the optimization of IMNRT plans by a commercial treatment planning optimization algorithm, potentially allowing IMNRT to achieve similar conformality in treatment as photon IMRT. The only remaining requirements for the delivery of very highly modulated neutron treatments are incremental improvements upon already implemented hardware systems that should be readily achievable.« less

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

Guy, Jean-Baptiste; Falk, Alexander T.; Auberdiac, Pierre

Introduction: For patients with cervical cancer, intensity-modulated radiation therapy (IMRT) improves target coverage and allows dose escalation while reducing the radiation dose to organs at risk (OARs). In this study, we compared dosimetric parameters among 3-dimensional conformal radiotherapy (3D-CRT), “step-and-shoot” IMRT, and volumetric intensity-modulated arc radiotherapy (VMAT) in a series of patients with cervical cancer receiving definitive radiotherapy. Computed tomography (CT) scans of 10 patients with histologically proven cervical cancer treated with definitive radiation therapy (RT) from December 2008 to March 2010 at our department were selected for this study. The gross tumor volume (GTV) and clinical target volume (CTV)more » were delineated following the guidelines of the Gyn IMRT consortium that included cervix, uterus, parametrial tissues, and the pelvic nodes including presacral. The median age was 57 years (range: 30 to 85 years). All 10 patients had squamous cell carcinoma with Federation of Gynecology and Obstetrics (FIGO) stage IB-IIIB. All patients were treated by VMAT. OAR doses were significantly reduced for plans with intensity-modulated technique compared with 3D-CRT except for the dose to the vagina. Between the 2 intensity-modulated techniques, significant difference was observed for the mean dose to the small intestine, to the benefit of VMAT (p < 0.001). There was no improvement in terms of OARs sparing for VMAT although there was a tendency for a slightly decreased average dose to the rectum: − 0.65 Gy but not significant (p = 0.07). The intensity modulation techniques have many advantages in terms of quality indexes, and particularly OAR sparing, compared with 3D-CRT. Following the ongoing technologic developments in modern radiotherapy, it is essential to evaluate the intensity-modulated techniques on prospective studies of a larger scale.« less

Clinical evaluation of intensity-modulated radiotherapy for head and neck cancers

PubMed Central

Bhide, S A; Newbold, K L; Harrington, K J; Nutting, C M

2012-01-01

Radiotherapy and surgery are the principal curative modalities in treatment of head and neck cancer. Conventional two-dimensional and three-dimensional conformal radiotherapy result in significant side effects and altered quality of life. Intensity-modulated radiotherapy (IMRT) can spare the normal tissues, while delivering a curative dose to the tumour-bearing tissues. This article reviews the current role of IMRT in head and neck cancer from the point of view of normal tissue sparing, and also reviews the current published literature by individual head and neck cancer subsites. In addition, we briefly discuss the role of image guidance in head and neck IMRT, and future directions in this area. PMID:22556403

Development and clinical introduction of automated radiotherapy treatment planning for prostate cancer

NASA Astrophysics Data System (ADS)

Winkel, D.; Bol, G. H.; van Asselen, B.; Hes, J.; Scholten, V.; Kerkmeijer, L. G. W.; Raaymakers, B. W.

2016-12-01

To develop an automated radiotherapy treatment planning and optimization workflow to efficiently create patient specifically optimized clinical grade treatment plans for prostate cancer and to implement it in clinical practice. A two-phased planning and optimization workflow was developed to automatically generate 77Gy 5-field simultaneously integrated boost intensity modulated radiation therapy (SIB-IMRT) plans for prostate cancer treatment. A retrospective planning study (n  =  100) was performed in which automatically and manually generated treatment plans were compared. A clinical pilot (n  =  21) was performed to investigate the usability of our method. Operator time for the planning process was reduced to  <5 min. The retrospective planning study showed that 98 plans met all clinical constraints. Significant improvements were made in the volume receiving 72Gy (V72Gy) for the bladder and rectum and the mean dose of the bladder and the body. A reduced plan variance was observed. During the clinical pilot 20 automatically generated plans met all constraints and 17 plans were selected for treatment. The automated radiotherapy treatment planning and optimization workflow is capable of efficiently generating patient specifically optimized and improved clinical grade plans. It has now been adopted as the current standard workflow in our clinic to generate treatment plans for prostate cancer.

Cardiac Side-effects From Breast Cancer Radiotherapy.

PubMed

Taylor, C W; Kirby, A M

2015-11-01

Breast cancer radiotherapy reduces the risk of cancer recurrence and death. However, it usually involves some radiation exposure of the heart and analyses of randomised trials have shown that it can increase the risk of heart disease. Estimates of the absolute risks of radiation-related heart disease are needed to help oncologists plan each individual woman's treatment. The risk for an individual woman varies according to her estimated cardiac radiation dose and her background risk of ischaemic heart disease in the absence of radiotherapy. When it is known, this risk can then be compared with the absolute benefit of the radiotherapy. At present, many UK cancer centres are already giving radiotherapy with mean heart doses of less than 3 Gy and for most women the benefits of the radiotherapy will probably far outweigh the risks. Technical approaches to minimising heart dose in breast cancer radiotherapy include optimisation of beam angles, use of multileaf collimator shielding, intensity-modulated radiotherapy, treatment in a prone position, treatment in deep inspiration (including the use of breath-hold and gating techniques), proton therapy and partial breast irradiation. The multileaf collimator is suitable for many women with upper pole left breast cancers, but for women with central or lower pole cancers, breath-holding techniques are now recommended in national UK guidelines. Ongoing work aims to identify ways of irradiating pan-regional lymph nodes that are effective, involve minimal exposure of organs at risk and are feasible to plan, deliver and verify. These will probably include wide tangent-based field-in-field intensity-modulated radiotherapy or arc radiotherapy techniques in combination with deep inspiratory breath-hold, and proton beam irradiation for women who have a high predicted heart dose from intensity-modulated radiotherapy. Copyright © 2015 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

Sparing functional anatomical structures during intensity-modulated radiotherapy: an old problem, a new solution.

PubMed

Tan, Wenyong; Han, Guang; Wei, Shaozhong; Hu, Desheng

2014-08-01

During intensity-modulated radiotherapy, an organ is usually assumed to be functionally homogeneous and, generally, its anatomical and spatial heterogeneity with respect to radiation response are not taken into consideration. However, advances in imaging and radiation techniques as well as an improved understanding of the radiobiological response of organs have raised the possibility of sparing the critical functional structures within various organs at risk during intensity-modulated radiotherapy. Here, we discuss these structures, which include the critical brain structure, or neural nuclei, and the nerve fiber tracts in the CNS, head and neck structures related to radiation-induced salivary and swallowing dysfunction, and functional structures in the heart and lung. We suggest that these structures can be used as potential surrogate organs at risk in order to minimize their radiation dose and/or irradiated volume without compromising the dose coverage of the target volume during radiation treatment.

External beam techniques to boost cervical cancer when brachytherapy is not an option—theories and applications

PubMed Central

Kilic, Sarah; Khan, Atif J.; Beriwal, Sushil; Small, William

2017-01-01

The management of locally advanced cervical cancer relies on brachytherapy (BT) as an integral part of the radiotherapy delivery armamentarium. Occasionally, intracavitary BT is neither possible nor available. In these circumstances, post-external beam radiotherapy (EBRT) interstitial brachytherapy and/or hysterectomy may represent viable options that must be adequately executed in a timely manner. However, if these options are not applicable due to patient related or facility related reasons, a formal contingency plan should be in place. Innovative EBRT techniques such as intensity modulated and stereotactic radiotherapy may be considered for patients unable to undergo brachytherapy. Relying on provocative arguments and recent data, this review explores the rationale for and limitations of non-brachytherapy substitutes in that setting aiming to establish a formal process for the optimal execution of this alternative plan. PMID:28603722

Radiation therapy planning with photons and protons for early and advanced breast cancer: an overview

PubMed Central

Weber, Damien C; Ares, Carmen; Lomax, Antony J; Kurtz, John M

2006-01-01

Postoperative radiation therapy substantially decreases local relapse and moderately reduces breast cancer mortality, but can be associated with increased late mortality due to cardiovascular morbidity and secondary malignancies. Sophistication of breast irradiation techniques, including conformal radiotherapy and intensity modulated radiation therapy, has been shown to markedly reduce cardiac and lung irradiation. The delivery of more conformal treatment can also be achieved with particle beam therapy using protons. Protons have superior dose distributional qualities compared to photons, as dose deposition occurs in a modulated narrow zone, called the Bragg peak. As a result, further dose optimization in breast cancer treatment can be reasonably expected with protons. In this review, we outline the potential indications and benefits of breast cancer radiotherapy with protons. Comparative planning studies and preliminary clinical data are detailed and future developments are considered. PMID:16857055

Iterative dataset optimization in automated planning: Implementation for breast and rectal cancer radiotherapy.

PubMed

Fan, Jiawei; Wang, Jiazhou; Zhang, Zhen; Hu, Weigang

2017-06-01

To develop a new automated treatment planning solution for breast and rectal cancer radiotherapy. The automated treatment planning solution developed in this study includes selection of the iterative optimized training dataset, dose volume histogram (DVH) prediction for the organs at risk (OARs), and automatic generation of clinically acceptable treatment plans. The iterative optimized training dataset is selected by an iterative optimization from 40 treatment plans for left-breast and rectal cancer patients who received radiation therapy. A two-dimensional kernel density estimation algorithm (noted as two parameters KDE) which incorporated two predictive features was implemented to produce the predicted DVHs. Finally, 10 additional new left-breast treatment plans are re-planned using the Pinnacle 3 Auto-Planning (AP) module (version 9.10, Philips Medical Systems) with the objective functions derived from the predicted DVH curves. Automatically generated re-optimized treatment plans are compared with the original manually optimized plans. By combining the iterative optimized training dataset methodology and two parameters KDE prediction algorithm, our proposed automated planning strategy improves the accuracy of the DVH prediction. The automatically generated treatment plans using the dose derived from the predicted DVHs can achieve better dose sparing for some OARs without compromising other metrics of plan quality. The proposed new automated treatment planning solution can be used to efficiently evaluate and improve the quality and consistency of the treatment plans for intensity-modulated breast and rectal cancer radiation therapy. © 2017 American Association of Physicists in Medicine.

Multi-GPU configuration of 4D intensity modulated radiation therapy inverse planning using global optimization

NASA Astrophysics Data System (ADS)

Hagan, Aaron; Sawant, Amit; Folkerts, Michael; Modiri, Arezoo

2018-01-01

We report on the design, implementation and characterization of a multi-graphic processing unit (GPU) computational platform for higher-order optimization in radiotherapy treatment planning. In collaboration with a commercial vendor (Varian Medical Systems, Palo Alto, CA), a research prototype GPU-enabled Eclipse (V13.6) workstation was configured. The hardware consisted of dual 8-core Xeon processors, 256 GB RAM and four NVIDIA Tesla K80 general purpose GPUs. We demonstrate the utility of this platform for large radiotherapy optimization problems through the development and characterization of a parallelized particle swarm optimization (PSO) four dimensional (4D) intensity modulated radiation therapy (IMRT) technique. The PSO engine was coupled to the Eclipse treatment planning system via a vendor-provided scripting interface. Specific challenges addressed in this implementation were (i) data management and (ii) non-uniform memory access (NUMA). For the former, we alternated between parameters over which the computation process was parallelized. For the latter, we reduced the amount of data required to be transferred over the NUMA bridge. The datasets examined in this study were approximately 300 GB in size, including 4D computed tomography images, anatomical structure contours and dose deposition matrices. For evaluation, we created a 4D-IMRT treatment plan for one lung cancer patient and analyzed computation speed while varying several parameters (number of respiratory phases, GPUs, PSO particles, and data matrix sizes). The optimized 4D-IMRT plan enhanced sparing of organs at risk by an average reduction of 26% in maximum dose, compared to the clinical optimized IMRT plan, where the internal target volume was used. We validated our computation time analyses in two additional cases. The computation speed in our implementation did not monotonically increase with the number of GPUs. The optimal number of GPUs (five, in our study) is directly related to the hardware specifications. The optimization process took 35 min using 50 PSO particles, 25 iterations and 5 GPUs.

Multi-GPU configuration of 4D intensity modulated radiation therapy inverse planning using global optimization.

PubMed

Hagan, Aaron; Sawant, Amit; Folkerts, Michael; Modiri, Arezoo

2018-01-16

We report on the design, implementation and characterization of a multi-graphic processing unit (GPU) computational platform for higher-order optimization in radiotherapy treatment planning. In collaboration with a commercial vendor (Varian Medical Systems, Palo Alto, CA), a research prototype GPU-enabled Eclipse (V13.6) workstation was configured. The hardware consisted of dual 8-core Xeon processors, 256 GB RAM and four NVIDIA Tesla K80 general purpose GPUs. We demonstrate the utility of this platform for large radiotherapy optimization problems through the development and characterization of a parallelized particle swarm optimization (PSO) four dimensional (4D) intensity modulated radiation therapy (IMRT) technique. The PSO engine was coupled to the Eclipse treatment planning system via a vendor-provided scripting interface. Specific challenges addressed in this implementation were (i) data management and (ii) non-uniform memory access (NUMA). For the former, we alternated between parameters over which the computation process was parallelized. For the latter, we reduced the amount of data required to be transferred over the NUMA bridge. The datasets examined in this study were approximately 300 GB in size, including 4D computed tomography images, anatomical structure contours and dose deposition matrices. For evaluation, we created a 4D-IMRT treatment plan for one lung cancer patient and analyzed computation speed while varying several parameters (number of respiratory phases, GPUs, PSO particles, and data matrix sizes). The optimized 4D-IMRT plan enhanced sparing of organs at risk by an average reduction of [Formula: see text] in maximum dose, compared to the clinical optimized IMRT plan, where the internal target volume was used. We validated our computation time analyses in two additional cases. The computation speed in our implementation did not monotonically increase with the number of GPUs. The optimal number of GPUs (five, in our study) is directly related to the hardware specifications. The optimization process took 35 min using 50 PSO particles, 25 iterations and 5 GPUs.

External Beam Radiotherapy for Prostate Cancer Patients on Anticoagulation Therapy: How Significant is the Bleeding Toxicity?

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

Choe, Kevin S.; Jani, Ashesh B.; Liauw, Stanley L., E-mail: sliauw@radonc.uchicago.ed

Purpose: To characterize the bleeding toxicity associated with external beam radiotherapy for prostate cancer patients receiving anticoagulation (AC) therapy. Methods and Materials: The study cohort consisted of 568 patients with adenocarcinoma of the prostate who were treated with definitive external beam radiotherapy. Of these men, 79 were receiving AC therapy with either warfarin or clopidogrel. All patients were treated with three-dimensional conformal radiotherapy or intensity-modulated radiotherapy. Bleeding complications were recorded during treatment and subsequent follow-up visits. Results: With a median follow-up of 48 months, the 4-year actuarial risk of Grade 3 or worse bleeding toxicity was 15.5% for those receivingmore » AC therapy compared with 3.6% among those not receiving AC (p < .0001). On multivariate analysis, AC therapy was the only significant factor associated with Grade 3 or worse bleeding (p < .0001). For patients taking AC therapy, the crude rate of bleeding was 39.2%. Multivariate analysis within the AC group demonstrated that a higher radiotherapy dose (p = .0408), intensity-modulated radiotherapy (p = 0.0136), and previous transurethral resection of the prostate (p = .0001) were associated with Grade 2 or worse bleeding toxicity. Androgen deprivation therapy was protective against bleeding, with borderline significance (p = 0.0599). Dose-volume histogram analysis revealed that Grade 3 or worse bleeding was minimized if the percentage of the rectum receiving >=70 Gy was <10% or the rectum receiving >=50 Gy was <50%. Conclusion: Patients taking AC therapy have a substantial risk of bleeding toxicity from external beam radiotherapy. In this setting, dose escalation or intensity-modulated radiotherapy should be used judiciously. With adherence to strict dose-volume histogram criteria and minimizing hotspots, the risk of severe bleeding might be reduced.« less

Postoperative Intensity-Modulated Radiotherapy in Low-Risk Endometrial Cancers: Final Results of a Phase I Study

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

Macchia, Gabriella, E-mail: gmacchia@rm.unicatt.i; Cilla, Savino M.P.; Ferrandina, Gabriella

2010-04-15

Purpose: To determine the maximum tolerated dose of short-course radiotherapy (intensity-modulated radiotherapy technique) to the upper two thirds of the vagina in endometrial cancers with low risk of local recurrence. Patients and Methods: A Phase I clinical trial was performed. Eligible patients had low-risk resected primary endometrial adenocarcinomas. Radiotherapy was delivered in 5 fractions over 1 week. The planning target volume was the clinical target volume plus 5 mm. The clinical target volume was defined as the upper two thirds of the vagina as evidenced at CT simulation by a vaginal radio-opaque device. The planning target volume was irradiated bymore » a seven-field intensity-modulated radiotherapy technique, planned by the Plato Sunrise inverse planning system. A first cohort of 6 patients received 25 Gy (5-Gy fractions), and a subsequent cohort received 30 Gy (6-Gy fractions). The Common Toxicity Criteria scale, version 3.0, was used to score toxicity. Results: Twelve patients with endometrial cancer were enrolled. Median age was 58 years (range, 49-74 years). Pathologic stage was IB (83.3%) and IC (16.7%). Median tumor size was 30 mm (range, 15-50 mm). All patients completed the prescribed radiotherapy. No patient experienced a dose-limiting toxicity at the first level, and the radiotherapy dose was escalated from 25 to 30 Gy. No patients at the second dose level experienced dose-limiting toxicity. The most common Grade 2 toxicity was gastrointestinal, which was tolerable and manageable. Conclusions: The maximum tolerated dose of short-course radiotherapy was 30 Gy at 6 Gy per fraction. On the basis of this result, we are conducting a Phase II study with radiotherapy delivered at 30 Gy.« less

Beam orientation optimization for intensity-modulated radiation therapy using mixed integer programming

NASA Astrophysics Data System (ADS)

Yang, Ruijie; Dai, Jianrong; Yang, Yong; Hu, Yimin

2006-08-01

The purpose of this study is to extend an algorithm proposed for beam orientation optimization in classical conformal radiotherapy to intensity-modulated radiation therapy (IMRT) and to evaluate the algorithm's performance in IMRT scenarios. In addition, the effect of the candidate pool of beam orientations, in terms of beam orientation resolution and starting orientation, on the optimized beam configuration, plan quality and optimization time is also explored. The algorithm is based on the technique of mixed integer linear programming in which binary and positive float variables are employed to represent candidates for beam orientation and beamlet weights in beam intensity maps. Both beam orientations and beam intensity maps are simultaneously optimized in the algorithm with a deterministic method. Several different clinical cases were used to test the algorithm and the results show that both target coverage and critical structures sparing were significantly improved for the plans with optimized beam orientations compared to those with equi-spaced beam orientations. The calculation time was less than an hour for the cases with 36 binary variables on a PC with a Pentium IV 2.66 GHz processor. It is also found that decreasing beam orientation resolution to 10° greatly reduced the size of the candidate pool of beam orientations without significant influence on the optimized beam configuration and plan quality, while selecting different starting orientations had large influence. Our study demonstrates that the algorithm can be applied to IMRT scenarios, and better beam orientation configurations can be obtained using this algorithm. Furthermore, the optimization efficiency can be greatly increased through proper selection of beam orientation resolution and starting beam orientation while guaranteeing the optimized beam configurations and plan quality.

Comparison of optimization algorithms in intensity-modulated radiation therapy planning

NASA Astrophysics Data System (ADS)

Kendrick, Rachel

Intensity-modulated radiation therapy is used to better conform the radiation dose to the target, which includes avoiding healthy tissue. Planning programs employ optimization methods to search for the best fluence of each photon beam, and therefore to create the best treatment plan. The Computational Environment for Radiotherapy Research (CERR), a program written in MATLAB, was used to examine some commonly-used algorithms for one 5-beam plan. Algorithms include the genetic algorithm, quadratic programming, pattern search, constrained nonlinear optimization, simulated annealing, the optimization method used in Varian EclipseTM, and some hybrids of these. Quadratic programing, simulated annealing, and a quadratic/simulated annealing hybrid were also separately compared using different prescription doses. The results of each dose-volume histogram as well as the visual dose color wash were used to compare the plans. CERR's built-in quadratic programming provided the best overall plan, but avoidance of the organ-at-risk was rivaled by other programs. Hybrids of quadratic programming with some of these algorithms seems to suggest the possibility of better planning programs, as shown by the improved quadratic/simulated annealing plan when compared to the simulated annealing algorithm alone. Further experimentation will be done to improve cost functions and computational time.

SU-F-T-198: Dosimetric Comparison of Carbon and Proton Radiotherapy for Recurrent Nasopharynx Carcinoma

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

Sheng, Y; Zhao, J; Wang, W

2016-06-15

Purpose: Various radiotherapy planning methods for locally recurrent nasopharynx carcinoma (R-NPC) have been proposed. The purpose of this study was to compare carbon and proton therapy for the treatment of R-NPC in terms of dose coverage for target volume and sparing for organs at risk (OARs). Methods: Six patients who were suffering from R-NPC and treated using carbon therapy were selected for this study. Treatment plans with a total dose of 57.5Gy (RBE) in 23 fractions were made using SIEMENS Syngo V11. An intensity-modulated radiotherapy optimization method was chosen for carbon plans (IMCT) while for proton plans both intensity-modulated radiotherapymore » (IMPT) and single beam optimization (proton-SBO) methods were chosen. Dose distributions, dose volume parameters, and selected dosimetric indices for target volumes and OARs were compared for all treatment plans. Results: All plans provided comparable PTV coverage. The volume covered by 95% of the prescribed dose was comparable for all three plans. The average values were 96.11%, 96.24% and 96.11% for IMCT, IMPT, and proton-SBO respectively. A significant reduction of the 80% and 50% dose volumes were observed for the IMCT plans compared to the IMPT and proton-SBO plans. Critical organs lateral to the target such as brain stem and spinal cord were better spared by IMPT than by proton-SBO, while IMCT spared those organs best. For organs in the beam path, such as parotid glands, the mean dose results were similar for all three plans. Conclusion: Carbon plans yielded better dose conformity than proton plans. They provided similar or better target coverage while significantly lowering the dose for normal tissues. Dose sparing for critical organs in IMPT plans was better than proton-SBO, however, IMPT is known to be more sensitive to range uncertainties. For proton plans it is essential to find a balance between the two optimization methods.« less

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

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

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

2006-10-01

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

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

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

Tsai, Jen-San, E-mail: jen-san.tsai@verizon.net; 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 rotationalmore » 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 within {+-} 4.5 mm coordinates shifting. IGRT using XVIcbs is critical to IMRT for prostate and H and N, especially SRT, SRS, and SBRT. To optimize this modality of IGRT, a vigilant QA program is indispensable. Prostate IGRT reveals treatment accuracy as subject to coordinates' adjustments; otherwise a 4.5-mm margin is required to allow for full dose coverage of the clinical target volume, notwithstanding toxicity to normal tissues.« less

[Guidelines for external radiotherapy and brachytherapy: introduction to the 2nd edition. Société française de radiothérapie oncologique (SFRO)].

PubMed

Mahé, M-A; Barillot, I; Chauvet, B

2014-10-01

In 2007, a first edition was published with the objective to produce guidelines for optimization, harmonization and homogenization of practices in external radiation therapy in France. The second edition, including brachytherapy, has the same objective and takes into account recent technologic improvements (intensity modulation radiation therapy, stereotactic radiotherapy, and 3-dimension brachytherapy) and recent results of the literature. The first part is about daily use of general principles (quality, security, image-guided radiation therapy) and the second is to describe each step of treatment of main cancers. Copyright © 2014 Société française de radiothérapie oncologique (SFRO). Published by Elsevier SAS. All rights reserved.

Clinical and dosimetric implications of intensity-modulated radiotherapy for early-stage glottic carcinoma

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

Ward, Matthew Christopher, E-mail: wardm3@ccf.org; Pham, Yvonne D.; Kotecha, Rupesh

2016-04-01

Conventional parallel-opposed radiotherapy (PORT) is the established standard technique for early-stage glottic carcinoma. However, case reports have reported the utility of intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT) with or without image guidance (image-guided radiotherapy, IGRT) in select patients. The proposed advantages of IMRT/VMAT include sparing of the carotid artery, thyroid gland, and the remaining functional larynx, although these benefits remain unclear. The following case study presents a patient with multiple vascular comorbidities treated with VMAT for early-stage glottic carcinoma. A detailed explanation of the corresponding treatment details, dose-volume histogram (DVH) analysis, and a review of the relevant literaturemore » are provided. Conventional PORT remains the standard of care for early-stage glottic carcinoma. IMRT or VMAT may be beneficial for select patients, although great care is necessary to avoid a geographical miss. Clinical data supporting the benefit of CRT are lacking. Therefore, these techniques should be used with caution and only in selected patients.« less

Improving IMRT delivery efficiency using intensity limits during inverse planning.

PubMed

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

2005-05-01

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

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

PubMed

Nutting, C M

2012-07-01

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

Urethra sparing - potential of combined Nickel-Titanium stent and intensity modulated radiation therapy in prostate cancer.

PubMed

Thomsen, Jakob Borup; Arp, Dennis Tideman; Carl, Jesper

2012-05-01

To investigate a novel method for sparing urethra in external beam radiotherapy of prostate cancer and to evaluate the efficacy of such a treatment in terms of tumour control using a mathematical model. This theoretical study includes 20 patients previously treated for prostate cancer using external beam radiotherapy. All patients had a Nickel-Titanium (Ni-Ti) stent inserted into the prostate part of urethra. The stent has been used during the treatment course as an internal marker for patient positioning prior to treatment. In this study the stent is used for delineating urethra while intensity modulated radiotherapy was used for lowering dose to urethra. Evaluation of the dose plans were performed using a tumour control probability model based on the concept of uniform equivalent dose. The feasibility of the urethra dose reduction method is validated and a reduction of about 17% is shown to be possible. Calculations suggest a nearly preserved tumour control probability. A new concept for urethra dose reduction is presented. The method relies on the use of a Ni-Ti stent as a fiducial marker combined with intensity modulated radiotherapy. Theoretical calculations suggest preserved tumour control. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

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

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

Zelefsky, Michael J., E-mail: zelefskm@mskcc.org; Greco, Carlo; Motzer, Robert

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 highmore » 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.« less

Intensity modulated radiotherapy and 3D conformal radiotherapy for whole breast irradiation: a comparative dosimetric study and introduction of a novel qualitative index for plan evaluation, the normal tissue index

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

Yim, Jackie; Suttie, Clare; Bromley, Regina

We report on a retrospective dosimetric study, comparing 3D conformal radiotherapy (3DCRT) and hybrid intensity modulated radiotherapy (hIMRT). We evaluated plans based on their planning target volume coverage, dose homogeneity, dose to organs at risk (OARs) and exposure of normal tissue to radiation. The Homogeneity Index (HI) was used to assess the dose homogeneity in the target region, and we describe a new index, the normal tissue index (NTI), to assess the dose in the normal tissue inside the tangent treatment portal. Plans were generated for 25 early-stage breast cancer patients, using a hIMRT technique. These were compared with themore » 3DCRT plans of the treatment previously received by the patients. Plan quality was evaluated using the HI, NTI and dose to OARs. The hIMRT technique was significantly more homogenous than the 3DCRT technique, while maintaining target coverage. The hIMRT technique was also superior at minimising the amount of tissue receiving D{sub 105%} and above (P < 0.0001). The ipsilateral lung and contralateral breast maximum were significantly lower in the hIMRT plans (P < 0.05 and P < 0.005), but the 3DCRT technique achieved a lower mean heart dose in left-sided breast cancer patients (P < 0.05). Hybrid intensity modulated radiotherapy plans achieved improved dose homogeneity compared to the 3DCRT plans and superior outcome with regard to dose to normal tissues. We propose that the addition of both HI and NTI in evaluating the quality of intensity modulated radiotherapy (IMRT) breast plans provides clinically relevant comparators which more accurately reflect the new paradigm of treatment goals and outcomes in the era of breast IMRT.« less

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

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

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

2012-03-01

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

SU-F-P-52: A Meta-Analysis of Controlled Clinical Trials Comparing Elective Nodal Irradiation with Involved-Field Irradiation for Conformal Or Intensity-Modulated Radiotherapy in Patients with Esophageal Cancer

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

Bai, W; Zhang, R; Zhou, Z

Purpose: To compare elective nodal irradiation with involved-field irradiation for three-dimensional conformal radiotherapy or intensity-modulated radiotherapy in patients with esophageal cancer by a metaanalysis. Methods: Wanfang, CNKI, VIP, CBM databases, PubMed, Embase and Cochrane Library were searched to identify the controlled clinical trials of elective nodal irradiation with involved-field irradiation for three-dimensional conformal radiotherapy or intensity-modulated radiotherapy in patients with esophageal cancer. The obtained data were analyzed using Stata 11.0. The difference between two groups was estimated by calculating the odds ratio (OR) with 95% confidence interval (95% CI). Results: A total of 12 controlled clinical trials involving 1095 esophagealmore » cancer patients, which were selected according to inclusion and exclusion criteria, were included in this meta-analysis. The meta-analysis showed that the elective nodal irradiation group reduced the rates of out-field failure comparing with involved-field irradiation group (OR=3.727, P=0.007). However, the rates of ≥grades 3 acute radiation pneumonitis and esophagitis were significantly higher in the elective nodal irradiation group than in the involved-field irradiation group (OR=0.348, P=0.001, OR=0.385, P=0.000). 1-, 2-, 3-year local control rates (OR=0.966, P=0.837, OR=0.946, P=0.781; OR=0.732P=0.098) and 1-, 3-, 5-year survival rates were similar in the two groups ( OR=0.966, P=0.837; OR=0.946, P=0.781; OR=0.732, P=0.098; OR=0.952, P=0.756; OR=1.149, P=0.422; OR=0.768, P=0.120). It is the same with the rates of distant metastasis (OR=0.986, P=0.937). Conclusion: Compared with involved-field irradiation, the elective nodal irradiation can reduce the rates of out-field failure for three-dimensional conformal radiotherapy or intensity-modulated radiotherapy in patients with esophageal cancer. However, its advantage of local control and survival rates is not obvious and it increases the incidence of toxicities.« less

Predictive factors for acute radiation pneumonitis in postoperative intensity modulated radiation therapy and volumetric modulated arc therapy of esophageal cancer.

PubMed

Zhao, Yaqin; Chen, Lu; Zhang, Shu; Wu, Qiang; Jiang, Xiaoqin; Zhu, Hong; Wang, Jin; Li, Zhiping; Xu, Yong; Zhang, Ying Jie; Bai, Sen; Xu, Feng

2015-01-01

Radiation pneumonitis (RP) is a common side reaction in radiotherapy for esophageal cancer. There are few reports about RP in esophageal cancer patients receiving postoperative intensity modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT). This study aims to analyze clinical or dosimetric factors associated with RP, and provides data for radiotherapy planning. We reviewed 68 postoperative esophageal cancer patients who were treated with radiotherapy at the West China Hospital from October 2010 to November 2012 to identify any correlation between the clinical or dosimetric parameters and acute radiation pneumonitis (ARP) or severe acute radiation pneumonitis (SARP) by t-test, chi-square test, and logistic regression analysis. Of the 68 patients, 33 patients (48.5%) developed ARP, 13 of which (19.1%) developed SARP. Of these 33 patients, 8 (11.8%), 12 (17.6%), 11 (16.2%), and 2 (2.9%) patients were grade 1, 2, 3, and 4 ARP, respectively. Univariate analysis showed that lung infection during radiotherapy, use of VMAT, mean lung dose (MLD), and dosimetric parameters (e.g. V20, V30) are significantly correlated with RP. Multivariate analysis found that lung infection during radiotherapy, MLD ≥ 12 Gy, and V30 ≥ 13% are significantly correlated with an increased risk of RP. Lung infection during radiotherapy and low radiation dose volume distribution were predictive factors associated with RP and should be accounted for during radiation planning.

Improved normal tissue sparing in head and neck radiotherapy using biological cost function based-IMRT.

PubMed

Anderson, N; Lawford, C; Khoo, V; Rolfo, M; Joon, D L; Wada, M

2011-12-01

Intensity-modulated radiotherapy (IMRT) has reduced the impact of acute and late toxicities associated with head and neck radiotherapy. Treatment planning system (TPS) advances in biological cost function based optimization (BBO) and improved segmentation techniques have increased organ at risk (OAR) sparing compared to conventional dose-based optimization (DBO). A planning study was undertaken to compare OAR avoidance in DBO and BBO treatment planning. Simultaneous integrated boost treatment plans were produced for 10 head and neck patients using both planning systems. Plans were compared for tar get coverage and OAR avoidance. Comparisons were made using the BBO TPS Monte Carlo dose engine to eliminate differences due to inherent algorithms. Target coverage (V95%) was maintained for both solutions. BBO produced lower OAR doses, with statistically significant improvement to left (12.3%, p = 0.005) and right parotid mean dose (16.9%, p = 0.004), larynx V50_Gy (71.0%, p = 0.005), spinal cord (21.9%, p < 0.001) and brain stem dose maximums (31.5%, p = 0.002). This study observed improved OAR avoidance with BBO planning. Further investigations will be undertaken to review any clinical benefit of this improved planned dosimetry.

Improved Normal Tissue Sparing in Head and Neck Radiotherapy Using Biological Cost Function Based-IMRT

PubMed Central

Anderson, N.; Lawford, C.; Khoo, V.; Rolfo, M.; Joon, D. Lim; Wada, M.

2011-01-01

Intensity-modulated radiotherapy (IMRT) has reduced the impact of acute and late toxicities associated with head and neck radiotherapy. Treatment planning system (TPS) advances in biological cost function based optimization (BBO) and improved segmentation techniques have increased organ at risk (OAR) sparing compared to conventional dose-based optimization (DBO). A planning study was undertaken to compare OAR avoidance in DBO and BBO treatment planning. Simultaneous integrated boost treatment plans were produced for 10 head and neck patients using both planning systems. Plans were compared for tar get coverage and OAR avoidance. Comparisons were made using the BBO TPS Monte Carlo dose engine to eliminate differences due to inherent algorithms. Target coverage (V95%) was maintained for both solutions. BBO produced lower OAR doses, with statistically significant improvement to left (12.3%, p = 0.005) and right parotid mean dose (16.9%, p = 0.004), larynx V50 Gy (71.0%, p = 0.005), spinal cord (21.9%, p < 0.001) and brain stem dose maximums (31.5%, p = 0.002). This study observed improved OAR avoidance with BBO planning. Further investigations will be undertaken to review any clinical benefit of this improved planned dosimetry. PMID:22066597

Projected Improvements in Accelerated Partial Breast Irradiation Using a Novel Breast Stereotactic Radiotherapy Device: A Dosimetric Analysis.

PubMed

Snider, James W; Mutaf, Yildirim; Nichols, Elizabeth; Hall, Andrea; Vadnais, Patrick; Regine, William F; Feigenberg, Steven J

2017-01-01

Accelerated partial breast irradiation has caused higher than expected rates of poor cosmesis. At our institution, a novel breast stereotactic radiotherapy device has demonstrated dosimetric distributions similar to those in brachytherapy. This study analyzed comparative dose distributions achieved with the device and intensity-modulated radiation therapy accelerated partial breast irradiation. Nine patients underwent computed tomography simulation in the prone position using device-specific immobilization on an institutional review board-approved protocol. Accelerated partial breast irradiation target volumes (planning target volume_10mm) were created per the National Surgical Adjuvant Breast and Bowel Project B-39 protocol. Additional breast stereotactic radiotherapy volumes using smaller margins (planning target volume_3mm) were created based on improved immobilization. Intensity-modulated radiation therapy and breast stereotactic radiotherapy accelerated partial breast irradiation plans were separately generated for appropriate volumes. Plans were evaluated based on established dosimetric surrogates of poor cosmetic outcomes. Wilcoxon rank sum tests were utilized to contrast volumes of critical structures receiving a percentage of total dose ( Vx). The breast stereotactic radiotherapy device consistently reduced dose to all normal structures with equivalent target coverage. The ipsilateral breast V20-100 was significantly reduced ( P < .05) using planning target volume_10mm, with substantial further reductions when targeting planning target volume_3mm. Doses to the chest wall, ipsilateral lung, and breast skin were also significantly lessened. The breast stereotactic radiotherapy device's uniform dosimetric improvements over intensity-modulated accelerated partial breast irradiation in this series indicate a potential to improve outcomes. Clinical trials investigating this benefit have begun accrual.

Stereotactic body radiotherapy for lung cancer: how much does it really cost?

PubMed

Lievens, Yolande; Obyn, Caroline; Mertens, Anne-Sophie; Van Halewyck, Dries; Hulstaert, Frank

2015-03-01

Despite the lack of randomized evidence, stereotactic body radiotherapy (SBRT) is being accepted as superior to conventional radiotherapy for patients with T1-2N0 non-small-cell lung cancer in the periphery of the lung and unfit or unwilling to undergo surgery. To introduce SBRT in a system of coverage with evidence development, a correct financing had to be determined. A time-driven activity-based costing model for radiotherapy was developed. Resource cost calculation of all radiotherapy treatments, standard and innovative, was conducted in 10 Belgian radiotherapy centers in the second half of 2012. The average cost of lung SBRT across the 10 centers (6221&OV0556;) is in the range of the average costs of standard fractionated 3D-conformal radiotherapy (5919&OV0556;) and intensity-modulated radiotherapy (7379&OV0556;) for lung cancer. Hypofractionated 3D-conformal radiotherapy and intensity-modulated radiotherapy schemes are less costly (3993&OV0556; respectively 4730&OV0556;). The SBRT cost increases with the number of fractions and is highly dependent of personnel and equipment use. SBRT cost varies more by centre than conventional radiotherapy cost, reflecting different technologies, stages in the learning curve and a lack of clear guidance in this field. Time-driven activity-based costing of radiotherapy is feasible in a multicentre setup, resulting in real-life resource costs that can form the basis for correct reimbursement schemes, supporting an early yet controlled introduction of innovative radiotherapy techniques in clinical practice.

Critical Structure Sparing in Stereotactic Ablative Radiotherapy for Central Lung Lesions: Helical Tomotherapy vs. Volumetric Modulated Arc Therapy

PubMed Central

Chi, Alexander; Ma, Pan; Fu, Guishan; Hobbs, Gerry; Welsh, James S.; Nguyen, Nam P.; Jang, Si Young; Dai, Jinrong; Jin, Jing; Komaki, Ritsuko

2013-01-01

Background Helical tomotherapy (HT) and volumetric modulated arc therapy (VMAT) are both advanced techniques of delivering intensity-modulated radiotherapy (IMRT). Here, we conduct a study to compare HT and partial-arc VMAT in their ability to spare organs at risk (OARs) when stereotactic ablative radiotherapy (SABR) is delivered to treat centrally located early stage non-small-cell lung cancer or lung metastases. Methods 12 patients with centrally located lung lesions were randomly chosen. HT, 2 & 8 arc (Smart Arc, Pinnacle v9.0) plans were generated to deliver 70 Gy in 10 fractions to the planning target volume (PTV). Target and OAR dose parameters were compared. Each technique’s ability to meet dose constraints was further investigated. Results HT and VMAT plans generated essentially equivalent PTV coverage and dose conformality indices, while a trend for improved dose homogeneity by increasing from 2 to 8 arcs was observed with VMAT. Increasing the number of arcs with VMAT also led to some improvement in OAR sparing. After normalizing to OAR dose constraints, HT was found to be superior to 2 or 8-arc VMAT for optimal OAR sparing (meeting all the dose constraints) (p = 0.0004). All dose constraints were met in HT plans. Increasing from 2 to 8 arcs could not help achieve optimal OAR sparing for 4 patients. 2/4 of them had 3 immediately adjacent structures. Conclusion HT appears to be superior to VMAT in OAR sparing mainly in cases which require conformal dose avoidance of multiple immediately adjacent OARs. For such cases, increasing the number of arcs in VMAT cannot significantly improve OAR sparing. PMID:23577071

Dosimetric comparison between modulated arc therapy and static intensity modulated radiotherapy in thoracic esophageal cancer: a single institutional experience.

PubMed

Choi, Kyu Hye; Kim, Jina; Lee, Sea-Won; Kang, Young-Nam; Jang, HongSeok

2018-03-01

The objective of this study was to compare dosimetric characteristics of three-dimensional conformal radiotherapy (3D-CRT) and two types of intensity-modulated radiotherapy (IMRT) which are step-and-shoot intensity modulated radiotherapy (s-IMRT) and modulated arc therapy (mARC) for thoracic esophageal cancer and analyze whether IMRT could reduce organ-at-risk (OAR) dose. We performed 3D-CRT, s-IMRT, and mARC planning for ten patients with thoracic esophageal cancer. The dose-volume histogram for each plan was extracted and the mean dose and clinically significant parameters were analyzed. Analysis of target coverage showed that the conformity index (CI) and conformation number (CN) in mARC were superior to the other two plans (CI, p = 0.050; CN, p = 0.042). For the comparison of OAR, lung V 5 was lowest in s-IMRT, followed by 3D-CRT, and mARC (p = 0.033). s-IMRT and mARC had lower values than 3D-CRT for heart V 30 (p = 0.039), V 40 (p = 0.040), and V 50 (p = 0.032). Effective conservation of the lung and heart in thoracic esophageal cancer could be expected when using s-IMRT. The mARC was lower in lung V 10 , V 20 , and V 30 than in 3D-CRT, but could not be proven superior in lung V 5 . In conclusion, low-dose exposure to the lung and heart were expected to be lower in s-IMRT, reducing complications such as radiation pneumonitis or heart-related toxicities.

Falcon: automated optimization method for arbitrary assessment criteria

DOEpatents

Yang, Tser-Yuan; Moses, Edward I.; Hartmann-Siantar, Christine

2001-01-01

FALCON is a method for automatic multivariable optimization for arbitrary assessment criteria that can be applied to numerous fields where outcome simulation is combined with optimization and assessment criteria. A specific implementation of FALCON is for automatic radiation therapy treatment planning. In this application, FALCON implements dose calculations into the planning process and optimizes available beam delivery modifier parameters to determine the treatment plan that best meets clinical decision-making criteria. FALCON is described in the context of the optimization of external-beam radiation therapy and intensity modulated radiation therapy (IMRT), but the concepts could also be applied to internal (brachytherapy) radiotherapy. The radiation beams could consist of photons or any charged or uncharged particles. The concept of optimizing source distributions can be applied to complex radiography (e.g. flash x-ray or proton) to improve the imaging capabilities of facilities proposed for science-based stockpile stewardship.

Automatic treatment planning facilitates fast generation of high-quality treatment plans for esophageal cancer.

PubMed

Hansen, Christian Rønn; Nielsen, Morten; Bertelsen, Anders Smedegaard; Hazell, Irene; Holtved, Eva; Zukauskaite, Ruta; Bjerregaard, Jon Kroll; Brink, Carsten; Bernchou, Uffe

2017-11-01

The quality of radiotherapy planning has improved substantially in the last decade with the introduction of intensity modulated radiotherapy. The purpose of this study was to analyze the plan quality and efficacy of automatically (AU) generated VMAT plans for inoperable esophageal cancer patients. Thirty-two consecutive inoperable patients with esophageal cancer originally treated with manually (MA) generated volumetric modulated arc therapy (VMAT) plans were retrospectively replanned using an auto-planning engine. All plans were optimized with one full 6MV VMAT arc giving 60 Gy to the primary target and 50 Gy to the elective target. The planning techniques were blinded before clinical evaluation by three specialized oncologists. To supplement the clinical evaluation, the optimization time for the AU plan was recorded along with DVH parameters for all plans. Upon clinical evaluation, the AU plan was preferred for 31/32 patients, and for one patient, there was no difference in the plans. In terms of DVH parameters, similar target coverage was obtained between the two planning methods. The mean dose for the spinal cord increased by 1.8 Gy using AU (p = .002), whereas the mean lung dose decreased by 1.9 Gy (p < .001). The AU plans were more modulated as seen by the increase of 12% in mean MUs (p = .001). The median optimization time for AU plans was 117 min. The AU plans were in general preferred and showed a lower mean dose to the lungs. The automation of the planning process generated esophageal cancer treatment plans quickly and with high quality.

A dosimetric phantom study of thoracic radiotherapy based on three-dimensional modeling of mediastinal lymph nodes

PubMed Central

Zhang, Ji-Bin; Zhao, Li-Rong; Cui, Tian-Xiang; Chen, Xie-Wan; Yang, Qiao; Zhou, Yi-Bing; Chen, Zheng-Tang; Zhang, Shao-Xiang; Sun, Jian-Guo

2018-01-01

The aim of the present study was to investigate the optimal strategy and dosimetric measurement of thoracic radiotherapy based on three-dimensional (3D) modeling of mediastinal lymph nodes (MLNs). A 3D model of MLNs was constructed from a Chinese Visible Human female dataset. Image registration and fusion between reconstructed MLNs and original chest computed tomography (CT) images was conducted in the Eclipse™ treatment planning system (TPS). There were three plans, including 3D conformal radiotherapy (3D-CRT), intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT), which were designed based on 10 cases of simulated lung lesions (SLLs) and MLNs. The quality of these plans was evaluated via examining indexes, including conformity index (CI), homogeneity index and clinical target volume (CTV) coverage. Dose-volume histogram analysis was performed on SLL, MLNs and organs at risk (OARs). A Chengdu Dosimetric Phantom (CDP) was then drilled at specific MLNs according to 20 patients with thoracic tumors and of a medium-build. These plans were repeated on fused MLNs and CDP CT images in the Eclipse™ TPS. Radiation doses at the SLLs and MLNs of the CDP were measured and compared with calculated doses. The established 3D MLN model demonstrated the spatial location of MLNs and adjacent structures. Precise image registration and fusion were conducted between reconstructed MLNs and the original chest CT or CDP CT images. IMRT demonstrated greater values in CI, CTV coverage and OAR (lungs and spinal cord) protection, compared with 3D-CRT and VMAT (P<0.05). The deviation between the measured and calculated doses was within ± 10% at SLL, and at the 2R and 7th MLN stations. In conclusion, the 3D MLN model can benefit plan optimization and dosimetric measurement of thoracic radiotherapy, and when combined with CDP, it may provide a tool for clinical dosimetric monitoring. PMID:29556300

Dosimetric and radiobiological characterizations of prostate intensity-modulated radiotherapy and volumetric-modulated arc therapy: A single-institution review of ninety cases

PubMed Central

Khan, Muhammad Isa; Jiang, Runqing; Kiciak, Alexander; ur Rehman, Jalil; Afzal, Muhammad; Chow, James C. L.

2016-01-01

This study reviewed prostate volumetric-modulated arc therapy (VMAT) plans with intensity-modulated radiotherapy (IMRT) plans after prostate IMRT technique was replaced by VMAT in an institution. Characterizations of dosimetry and radiobiological variation in prostate were determined based on treatment plans of 40 prostate IMRT patients (planning target volume = 77.8–335 cm3) and 50 VMAT patients (planning target volume = 120–351 cm3) treated before and after 2013, respectively. Both IMRT and VMAT plans used the same dose-volume criteria in the inverse planning optimization. Dose-volume histogram, mean doses of target and normal tissues (rectum, bladder and femoral heads), dose-volume points (D99% of planning target volume; D30%, D50%, V30 Gy and V35 Gy of rectum and bladder; D5%, V14 Gy, V22 Gy of femoral heads), conformity index (CI), homogeneity index (HI), gradient index (GI), prostate tumor control probability (TCP), and rectal normal tissue complication probability (NTCP) based on the Lyman-Burman-Kutcher algorithm were calculated for each IMRT and VMAT plan. From our results, VMAT plan was found better due to its higher (1.05%) CI, lower (0.83%) HI and (0.75%) GI than IMRT. Comparing doses in normal tissues between IMRT and VMAT, it was found that IMRT mostly delivered higher doses of about 1.05% to the normal tissues than VMAT. Prostate TCP and rectal NTCP were found increased (1%) for VMAT than IMRT. It is seen that VMAT technique can decrease the dose-volume evaluation criteria for the normal tissues. Based on our dosimetric and radiobiological results in treatment plans, it is concluded that our VMAT implementation could produce comparable or slightly better target coverage and normal tissue sparing with a faster treatment time in prostate radiotherapy. PMID:27651562

Intensity-Modulated and 3D-Conformal Radiotherapy for Whole-Ventricular Irradiation as Compared With Conventional Whole-Brain Irradiation in the Management of Localized Central Nervous System Germ Cell Tumors

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

Chen, Michael Jenwei, E-mail: michaelchen@einstein.b; Silva Santos, Adriana da; Sakuraba, Roberto Kenji

Purpose: To compare the sparing potential of cerebral hemispheres with intensity-modulated radiotherapy (IMRT) and three-dimensional conformal radiotherapy (3D-CRT) for whole-ventricular irradiation (WVI) and conventional whole-brain irradiation (WBI) in the management of localized central nervous system germ cell tumors (CNSGCTs). Methods and Materials: Ten cases of patients with localized CNSGCTs and submitted to WVI by use of IMRT with or without a 'boost' to the primary lesion were selected. For comparison purposes, similar treatment plans were produced by use of 3D-CRT (WVI with or without boost) and WBI (opposed lateral fields with or without boost), and cerebral hemisphere sparing was evaluatedmore » at dose levels ranging from 2 Gy to 40 Gy. Results: The median prescription dose for WVI was 30.6 Gy (range, 25.2-37.5 Gy), and that for the boost was 16.5 Gy (range, 0-23.4 Gy). Mean irradiated cerebral hemisphere volumes were lower for WVI with IMRT than for 3D-CRT and were lower for WVI with 3D-CRT than for WBI. Intensity-modulated radiotherapy was associated with the lowest irradiated volumes, with reductions of 7.5%, 12.2%, and 9.0% at dose levels of 20, 30, and 40 Gy, respectively, compared with 3D-CRT. Intensity-modulated radiotherapy provided statistically significant reductions of median irradiated volumes at all dose levels (p = 0.002 or less). However, estimated radiation doses to peripheral areas of the body were 1.9 times higher with IMRT than with 3D-CRT. Conclusions: Although IMRT is associated with increased radiation doses to peripheral areas of the body, its use can spare a significant amount of normal central nervous system tissue compared with 3D-CRT or WBI in the setting of CNSGCT treatment.« less

SU-F-BRB-12: A Novel Haar Wavelet Based Approach to Deliver Non-Coplanar Intensity Modulated Radiotherapy Using Sparse Orthogonal Collimators

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

Nguyen, D; Ruan, D; Low, D

2015-06-15

Purpose: Existing efforts to replace complex multileaf collimator (MLC) by simple jaws for intensity modulated radiation therapy (IMRT) resulted in unacceptable compromise in plan quality and delivery efficiency. We introduce a novel fluence map segmentation method based on compressed sensing for plan delivery using a simplified sparse orthogonal collimator (SOC) on the 4π non-coplanar radiotherapy platform. Methods: 4π plans with varying prescription doses were first created by automatically selecting and optimizing 20 non-coplanar beams for 2 GBM, 2 head & neck, and 2 lung patients. To create deliverable 4π plans using SOC, which are two pairs of orthogonal collimators withmore » 1 to 4 leaves in each collimator bank, a Haar Fluence Optimization (HFO) method was used to regulate the number of Haar wavelet coefficients while maximizing the dose fidelity to the ideal prescription. The plans were directly stratified utilizing the optimized Haar wavelet rectangular basis. A matching number of deliverable segments were stratified for the MLC-based plans. Results: Compared to the MLC-based 4π plans, the SOC-based 4π plans increased the average PTV dose homogeneity from 0.811 to 0.913. PTV D98 and D99 were improved by 3.53% and 5.60% of the corresponding prescription doses. The average mean and maximal OAR doses slightly increased by 0.57% and 2.57% of the prescription doses. The average number of segments ranged between 5 and 30 per beam. The collimator travel time to create the segments decreased with increasing leaf numbers in the SOC. The two and four leaf designs were 1.71 and 1.93 times more efficient, on average, than the single leaf design. Conclusion: The innovative dose domain optimization based on compressed sensing enables uncompromised 4π non-coplanar IMRT dose delivery using simple rectangular segments that are deliverable using a sparse orthogonal collimator, which only requires 8 to 16 leaves yet is unlimited in modulation resolution. This work is supported in part by Varian Medical Systems, Inc. and NIH R43 CA18339.« less

Comparison of heart and coronary artery doses associated with intensity-modulated radiotherapy versus three-dimensional conformal radiotherapy for distal esophageal cancer.

PubMed

Kole, Thomas P; Aghayere, Osarhieme; Kwah, Jason; Yorke, Ellen D; Goodman, Karyn A

2012-08-01

To compare heart and coronary artery radiation exposure using intensity-modulated radiotherapy (IMRT) vs. four-field three-dimensional conformal radiotherapy (3D-CRT) treatment plans for patients with distal esophageal cancer undergoing chemoradiation. Nineteen patients with distal esophageal cancers treated with IMRT from March 2007 to May 2008 were identified. All patients were treated to 50.4 Gy with five-field IMRT plans. Theoretical 3D-CRT plans with four-field beam arrangements were generated. Dose-volume histograms of the planning target volume, heart, right coronary artery, left coronary artery, and other critical normal tissues were compared between the IMRT and 3D-CRT plans, and selected parameters were statistically evaluated using the Wilcoxon rank-sum test. Intensity-modulated radiotherapy treatment planning showed significant reduction (p < 0.05) in heart dose over 3D-CRT as assessed by average mean dose (22.9 vs. 28.2 Gy) and V30 (24.8% vs. 61.0%). There was also significant sparing of the right coronary artery (average mean dose, 23.8 Gy vs. 35.5 Gy), whereas the left coronary artery showed no significant improvement (mean dose, 11.2 Gy vs. 9.2 Gy), p = 0.11. There was no significant difference in percentage of total lung volume receiving at least 10, 15, or 20 Gy or in the mean lung dose between the planning methods. There were also no significant differences observed for the kidneys, liver, stomach, or spinal cord. Intensity-modulated radiotherapy achieved a significant improvement in target conformity as measured by the conformality index (ratio of total volume receiving 95% of prescription dose to planning target volume receiving 95% of prescription dose), with the mean conformality index reduced from 1.56 to 1.30 using IMRT. Treatment of patients with distal esophageal cancer using IMRT significantly decreases the exposure of the heart and right coronary artery when compared with 3D-CRT. Long-term studies are necessary to determine how this will impact on development of coronary artery disease and other cardiac complications. Copyright © 2012 Elsevier Inc. All rights reserved.

Dosimetric comparison between intensity-modulated with coplanar field and 3D conformal radiotherapy with noncoplanar field for postocular invasion tumor.

PubMed

Wenyong, Tu; Lu, Liu; Jun, Zeng; Weidong, Yin; Yun, Li

2010-01-01

This study presents a dosimetric optimization effort aiming to compare noncoplanar field (NCF) on 3 dimensions conformal radiotherapy (3D-CRT) and coplanar field (CF) on intensity-modulated radiotherapy (IMRT) planning for postocular invasion tumor. We performed a planning study on the computed tomography data of 8 consecutive patients with localized postocular invasion tumor. Four fields NCF 3D-CRT in the transverse plane with gantry angles of 0-10 degrees , 30-45 degrees , 240-270 degrees , and 310-335 degrees degrees were isocentered at the center of gravity of the target volume. The geometry of the beams was determined by beam's eye view. The same constraints were prepared with between CF IMRT optimization and NCF 3D-CRT treatment. The maximum point doses (D max) for the different optic pathway structures (OPS) with NCF 3D-CRT treatment should differ in no more than 3% from those with the NCF IMRT plan. Dose-volume histograms (DVHs) were obtained for all targets and organ at risk (OAR) with both treatment techniques. Plans with NCF 3D-CRT and CF IMRT constraints on target dose in homogeneity were computed, as well as the conformity index (CI) and homogeneity index (HI) in the target volume. The PTV coverage was optimal with both NCF 3D-CRT and CF IMRT plans in the 8 tumor sites. No difference was noted between the two techniques for the average D(max) and D(min) dose. NCF 3D-CRT and CF IMRT will yield similar results on CI. However, HI was a significant difference between NCF 3D-CRT and CF IMRT plan (p < 0.001). Physical endpoints for target showed the mean target dose to be low in the CF IMRT plan, caused by a large target dose in homogeneity (p < 0.001). The impact of NCF 3D-CRT versus CF IMRT set-up is very slight. NCF3D-CRT is one of the treatment options for postocular invasion tumor. However, constraints for OARs are needed. 2010 American Association of Medical Dosimetrists. Published by Elsevier Inc. All rights reserved.

High dose bystander effects in spatially fractionated radiation therapy

PubMed Central

Asur, Rajalakshmi; Butterworth, Karl T.; Penagaricano, Jose A.; Prise, Kevin M.; Griffin, Robert J.

2014-01-01

Traditional radiotherapy of bulky tumors has certain limitations. Spatially fractionated radiation therapy (GRID) and intensity modulated radiotherapy (IMRT) are examples of advanced modulated beam therapies that help in significant reductions in normal tissue damage. GRID refers to the delivery of a single high dose of radiation to a large treatment area that is divided into several smaller fields, while IMRT allows improved dose conformity to the tumor target compared to conventional three-dimensional conformal radiotherapy. In this review, we consider spatially fractionated radiotherapy approaches focusing on GRID and IMRT, and present complementary evidence from different studies which support the role of radiation induced signaling effects in the overall radiobiological rationale for these treatments. PMID:24246848

Retrospective evaluation of dosimetric quality for prostate carcinomas treated with 3D conformal, intensity modulated and volumetric modulated arc radiotherapy

PubMed Central

Crowe, Scott B; Kairn, Tanya; Middlebrook, Nigel; Hill, Brendan; Christie, David R H; Knight, Richard T; Kenny, John; Langton, Christian M; Trapp, Jamie V

2013-01-01

Introduction This study examines and compares the dosimetric quality of radiotherapy treatment plans for prostate carcinoma across a cohort of 163 patients treated across five centres: 83 treated with three-dimensional conformal radiotherapy (3DCRT), 33 treated with intensity modulated radiotherapy (IMRT) and 47 treated with volumetric modulated arc therapy (VMAT). Methods Treatment plan quality was evaluated in terms of target dose homogeneity and organs at risk (OAR), through the use of a set of dose metrics. These included the mean, maximum and minimum doses; the homogeneity and conformity indices for the target volumes; and a selection of dose coverage values that were relevant to each OAR. Statistical significance was evaluated using two-tailed Welch's T-tests. The Monte Carlo DICOM ToolKit software was adapted to permit the evaluation of dose metrics from DICOM data exported from a commercial radiotherapy treatment planning system. Results The 3DCRT treatment plans offered greater planning target volume dose homogeneity than the other two treatment modalities. The IMRT and VMAT plans offered greater dose reduction in the OAR: with increased compliance with recommended OAR dose constraints, compared to conventional 3DCRT treatments. When compared to each other, IMRT and VMAT did not provide significantly different treatment plan quality for like-sized tumour volumes. Conclusions This study indicates that IMRT and VMAT have provided similar dosimetric quality, which is superior to the dosimetric quality achieved with 3DCRT. PMID:26229621

Dosimetric study of the protection level of the bone marrow in patients with cervical or endometrial cancer for three radiotherapy techniques - 3D CRT, IMRT and VMAT. Study protocol.

NASA Astrophysics Data System (ADS)

Jodda, Agata; Urbański, Bartosz; Piotrowski, Tomasz; Malicki, Julian

2016-03-01

Background: The paper shows the methodology of an in-phantom study of the protection level of the bone marrow in patients with cervical or endometrial cancer for three radiotherapy techniques: three-dimensional conformal radiotherapy, intensity modulated radiotherapy, and volumetric modulated arc therapy, preceded by the procedures of image guidance. Methods/Design: The dosimetric evaluation of the doses will be performed in an in-house multi-element anthropomorphic phantom of the female pelvic area created by three-dimensional printing technology. The volume and position of the structures will be regulated according to the guidelines from the Bayesian network. The input data for the learning procedure of the model will be obtained from the retrospective analysis of imaging data obtained for 96 patients with endometrial cancer or cervical cancer treated with radiotherapy in our centre in 2008-2013. Three anatomical representations of the phantom simulating three independent clinical cases will be chosen. Five alternative treatment plans (1 × three-dimensional conformal radiotherapy, 2 × intensity modulated radiotherapy and 2 × volumetric modulated arc therapy) will be created for each representation. To simulate image-guided radiotherapy, ten specific recombinations will be designated, for each anatomical representation separately, reflecting possible changes in the volume and position of the phantom components. Discussion: The comparative analysis of planned measurements will identify discrepancies between calculated doses and doses that were measured in the phantom. Finally, differences between the doses cumulated in the hip plates performed by different techniques simulating the gynaecological patients' irradiation of dose delivery will be established. The results of this study will form the basis of the prospective clinical trial that will be designed for the assessment of hematologic toxicity and its correlation with the doses cumulated in the hip plates, for gynaecologic patients undergoing radiation therapy.

Cost of New Technologies in Prostate Cancer Treatment: Systematic Review of Costs and Cost Effectiveness of Robotic-assisted Laparoscopic Prostatectomy, Intensity-modulated Radiotherapy, and Proton Beam Therapy.

PubMed

Schroeck, Florian Rudolf; Jacobs, Bruce L; Bhayani, Sam B; Nguyen, Paul L; Penson, David; Hu, Jim

2017-11-01

Some of the high costs of robot-assisted radical prostatectomy (RARP), intensity-modulated radiotherapy (IMRT), and proton beam therapy may be offset by better outcomes or less resource use during the treatment episode. To systematically review the literature to identify the key economic trade-offs implicit in a particular treatment choice for prostate cancer. We systematically reviewed the literature according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) statement and protocol. We searched Medline, Embase, and Web of Science for articles published between January 2001 and July 2016, which compared the treatment costs of RARP, IMRT, or proton beam therapy to the standard treatment. We identified 37, nine, and three studies, respectively. RARP is costlier than radical retropubic prostatectomy for hospitals and payers. However, RARP has the potential for a moderate cost advantage for payers and society over a longer time horizon when optimal cancer and quality-of-life outcomes are achieved. IMRT is more expensive from a payer's perspective compared with three-dimensional conformal radiotherapy, but also more cost effective when defined by an incremental cost effectiveness ratio <$50 000 per quality-adjusted life year. Proton beam therapy is costlier than IMRT and its cost effectiveness remains unclear given the limited comparative data on outcomes. Using the Grades of Recommendation, Assessment, Development and Evaluation approach, the quality of evidence was low for RARP and IMRT, and very low for proton beam therapy. Treatment with new versus traditional technologies is costlier. However, given the low quality of evidence and the inconsistencies across studies, the precise difference in costs remains unclear. Attempts to estimate whether this increased cost is worth the expense are hampered by the uncertainty surrounding improvements in outcomes, such as cancer control and side effects of treatment. If the new technologies can consistently achieve better outcomes, then they may be cost effective. We review the cost and cost effectiveness of robot-assisted radical prostatectomy, intensity-modulated radiotherapy, and proton beam therapy in prostate cancer treatment. These technologies are costlier than their traditional counterparts. It remains unclear whether their use is associated with improved cure and reduced morbidity, and whether the increased cost is worth the expense. Published by Elsevier B.V.

Estimating the costs of intensity-modulated and 3-dimensional conformal radiotherapy in Ontario.

PubMed

Yong, J H E; McGowan, T; Redmond-Misner, R; Beca, J; Warde, P; Gutierrez, E; Hoch, J S

2016-06-01

Radiotherapy is a common treatment for many cancers, but up-to-date estimates of the costs of radiotherapy are lacking. In the present study, we estimated the unit costs of intensity-modulated radiotherapy (imrt) and 3-dimensional conformal radiotherapy (3D-crt) in Ontario. An activity-based costing model was developed to estimate the costs of imrt and 3D-crt in prostate cancer. It included the costs of equipment, staff, and supporting infrastructure. The framework was subsequently adapted to estimate the costs of radiotherapy in breast cancer and head-and-neck cancer. We also tested various scenarios by varying the program maturity and the use of volumetric modulated arc therapy (vmat) alongside imrt. From the perspective of the health care system, treating prostate cancer with imrt and 3D-crt respectively cost $12,834 and $12,453 per patient. The cost of radiotherapy ranged from $5,270 to $14,155 and was sensitive to analytic perspective, radiation technique, and disease site. Cases of head-and-neck cancer were the most costly, being driven by treatment complexity and fractions per treatment. Although imrt was more costly than 3D-crt, its cost will likely decline over time as programs mature and vmat is incorporated. Our costing model can be modified to estimate the costs of 3D-crt and imrt for various disease sites and settings. The results demonstrate the important role of capital costs in studies of radiotherapy cost from a health system perspective, which our model can accommodate. In addition, our study established the need for future analyses of imrt cost to consider how vmat affects time consumption.

The cost of radiotherapy in a decade of technology evolution.

PubMed

Van de Werf, Evelyn; Verstraete, Jan; Lievens, Yolande

2012-01-01

To quantify changes in radiotherapy costs occurring in a decade of medical-technological evolution. The activity-based costing (ABC) model of the University Hospitals Leuven (UHL) radiotherapy (RT) department was adapted to current RT standards. It allocated actual resource costs to the treatments based on the departmental work-flow and patient mix in 2009. A benchmark with the former model analyzed the cost increases related to changes in RT infrastructure and practice over 10 years. A considerable increase in total RT costs was observed, resulting from higher capital investments (96%) and personnel cost (103%), the latter dominating the total picture. Treatment delivery remains the most costly activity, boosted by the cost of improved quality assurance (QA), 23% of total product costs, coming along with more advanced RT techniques. Hence, cost increases at the product level are most obvious for complex treatments, such as intensity-modulated radiotherapy (IMRT), representing cost increases ranging between 38% and 88% compared to conformal approaches. The ABC model provides insight into the financial consequences of evolving technology and practice. Such data are a mandatory first step in our strive to prove RT cost-effectiveness and thus support optimal reimbursement and provision of radiotherapy departments. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

High dose chemoradiation for unresectable hilar cholangiocarcinomas using intensity modulated external beam radiotherapy: a single tertiary care centre experience

PubMed Central

Mehta, Shaesta; Kalyani, Nikhil; Chaudhari, Suresh; Dharia, Tejas; Shetty, Nitin; Chopra, Supriya; Goel, Mahesh; Kulkarni, Suyash; Shrivastava, Shyam Kishore

2017-01-01

Background We present results of patients diagnosed with unresectable hilar cholangiocarcinomas treated with high dose radiotherapy and concurrent chemotherapy. Methods From Aug 2005 to Dec 2012, 68 consecutive patients were treated. Fifty patients (group 1) presenting to us with obstructive jaundice were planned for endobiliary brachytherapy (EBBT 14 Gy) followed external beam radiotherapy (EBRT 45 Gy). Twenty-two patients (group 2) who had previously undergone biliary drainage underwent EBRT (57 Gy). All patients received injection Gemcitabine 300 mg/m2/weekly along with EBRT. Results Twenty-nine patients in group 1 and 22 patients in group 2 completed the treatment. Twenty-six (55%) patients achieved complete radiological response, 16 (64%) belonging to group 1 and 8 (44%) of group 2 (P=0.05). The median overall survival (MOS) was 17.5 and 16 months for group 1 and 2 respectively (P=0.07). The 1- and 2-year survival was 63%, and 18% for group I and 61% and 22% for group II respectively. The MOS was 5 months and 1 year survival was 14% for patients receiving EBBT only. MOS was significantly better after complete response (P=0.001). Conclusions Intensity modulated radiotherapy (IMRT) modulated high dose radiotherapy used either alone or with brachytherapy demonstrates potential to prolonged overall survival in unresectable hilar cholangiocarcinomas. PMID:28280622

Technological advances in radiotherapy of rectal cancer: opportunities and challenges.

PubMed

Appelt, Ane L; Sebag-Montefiore, David

2016-07-01

This review summarizes the available evidence for the use of modern radiotherapy techniques for chemoradiotherapy for rectal cancer, with specific focus on intensity-modulated radiotherapy (IMRT) and volumetric arc therapy (VMAT) techniques. The dosimetric benefits of IMRT and VMAT are well established, but prospective clinical studies are limited, with phase I-II studies only. Recent years have seen the publication of a few larger prospective patient series as well as some retrospective cohorts, several of which include much needed late toxicity data. Overall results are encouraging, as toxicity levels - although varying across reports - appear lower than for 3D conformal radiotherapy. Innovative treatment techniques and strategies which may be facilitated by the use of IMRT/VMAT include simultaneously integrated tumour boost, adaptive treatment, selective sparing of specific organs to enable chemotherapy escalation, and nonsurgical management. Few prospective studies of IMRT and VMAT exist, which causes uncertainty not just in regards to the clinical benefit of these technologies but also in the optimal use. The priority for future research should be subgroups of patients who might receive relatively greater benefit from innovative treatment techniques, such as patients receiving chemoradiotherapy with definitive intent and patients treated with dose escalation.

Dosimetric impact of different CT datasets for stereotactic treatment planning using 3D conformal radiotherapy or volumetric modulated arc therapy.

PubMed

Oechsner, Markus; Odersky, Leonhard; Berndt, Johannes; Combs, Stephanie Elisabeth; Wilkens, Jan Jakob; Duma, Marciana Nona

2015-12-01

The purpose of this study was to assess the impact on dose to the planning target volume (PTV) and organs at risk (OAR) by using four differently generated CT datasets for dose calculation in stereotactic body radiotherapy (SBRT) of lung and liver tumors. Additionally, dose differences between 3D conformal radiotherapy and volumetric modulated arc therapy (VMAT) plans calculated on these CT datasets were determined. Twenty SBRT patients, ten lung cases and ten liver cases, were retrospectively selected for this study. Treatment plans were optimized on average intensity projection (AIP) CTs using 3D conformal radiotherapy (3D-CRT) and volumetric modulated arc therapy (VMAT). Afterwards, the plans were copied to the planning CTs (PCT), maximum intensity projection (MIP) and mid-ventilation (MidV) CT datasets and dose was recalculated keeping all beam parameters and monitor units unchanged. Ipsilateral lung and liver volumes and dosimetric parameters for PTV (Dmean, D2, D98, D95), ipsilateral lung and liver (Dmean, V30, V20, V10) were determined and statistically analysed using Wilcoxon test. Significant but small mean differences were found for PTV dose between the CTs (lung SBRT: ≤2.5 %; liver SBRT: ≤1.6 %). MIPs achieved the smallest lung and the largest liver volumes. OAR mean doses in MIP plans were distinctly smaller than in the other CT datasets. Furthermore, overlapping of tumors with the diaphragm results in underestimated ipsilateral lung dose in MIP plans. Best agreement was found between AIP and MidV (lung SBRT). Overall, differences in liver SBRT were smaller than in lung SBRT and VMAT plans achieved slightly smaller differences than 3D-CRT plans. Only small differences were found for PTV parameters between the four CT datasets. Larger differences occurred for the doses to organs at risk (ipsilateral lung, liver) especially for MIP plans. No relevant differences were observed between 3D-CRT or VMAT plans. MIP CTs are not appropriate for OAR dose assessment. PCT, AIP and MidV resulted in similar doses. If a 4DCT is acquired PCT can be omitted using AIP or MidV for treatment planning.

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

PubMed

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

2015-09-01

The radiation dose delivered to the target by using different radiotherapy applications has been measured with the help of beryllium oxide (BeO) dosimeters to be placed inside the rando phantom. Three-Dimensional Conformal Radiotherapy (3DCRT), Intensity-Modulated Radiotherapy (IMRT) and Intensity-Modulated Arc Therapy (IMAT) have been used as radiotherapy application. Individual treatment plans have been made for the three radiotherapy applications of rando phantom. The section 4 on the phantom was selected as target and 200 cGy doses were delivered. After the dosimeters placed on section 4 (target) and the sections 2 and 6 (non-target) were irradiated, the result was read through the OSL technique on the Risø TL/OSL system. This procedure was repeated three times for each radiotherapy application. The doses delivered to the target and the non-target sections as a result of the 3DCRT, IMRT and IMAT plans were analyzed. The doses received by the target were measured as 204.71 cGy, 204.76 cGy and 205.65 cGy, respectively. The dose values obtained from treatment planning system (TPS) were compared to the dose values obtained using the OSL technique. It has been concluded that, the radiation dose can be measured with the OSL technique by using BeO dosimeters in medical practices. Copyright © 2015 Elsevier Ltd. All rights reserved.

Consensus Guidelines for Delineation of Clinical Target Volume for Intensity-Modulated Pelvic Radiotherapy in Postoperative Treatment of Endometrial and Cervical Cancer

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

Small, William; Mell, Loren K.; Anderson, Penny

2008-06-01

Purpose: To develop an atlas of the clinical target volume (CTV) definitions for postoperative radiotherapy of endometrial and cervical cancer to be used for planning pelvic intensity-modulated radiotherapy. Methods and Materials: The Radiation Therapy Oncology Group led an international collaberation of cooperative groups in the development of the atlas. The groups included the Radiation Therapy Oncology Group, Gynecologic Oncology Group, National Cancer Institute of Canada, European Society of Therapeutic Radiology and Oncology, and American College of Radiology Imaging Network. The members of the group were asked by questionnaire to define the areas that were to be included in the CTVmore » and to outline theses areas on individual computed tomography images. The initial formulation of the group began in late 2004 and culminated with a formal consensus conference in June 2005. Results: The committee achieved a consensus CTV definition for postoperative therapy for endometrial and cervical cancer. The CTV should include the common, external, and internal iliac lymph node regions. The upper 3.0 cm of the vagina and paravaginal soft tissue lateral to the vagina should also be included. For patients with cervical cancer, or endometrial cancer with cervical stromal invasion, it is also recommended that the CTV include the presacral lymph node region. Conclusion: This report serves as an international template for the definition of the CTV for postoperative intensity-modulated radiotherapy for endometrial and cervical cancer.« less

Optimization of equivalent uniform dose using the L-curve criterion.

PubMed

Chvetsov, Alexei V; Dempsey, James F; Palta, Jatinder R

2007-10-07

Optimization of equivalent uniform dose (EUD) in inverse planning for intensity-modulated radiation therapy (IMRT) prevents variation in radiobiological effect between different radiotherapy treatment plans, which is due to variation in the pattern of dose nonuniformity. For instance, the survival fraction of clonogens would be consistent with the prescription when the optimized EUD is equal to the prescribed EUD. One of the problems in the practical implementation of this approach is that the spatial dose distribution in EUD-based inverse planning would be underdetermined because an unlimited number of nonuniform dose distributions can be computed for a prescribed value of EUD. Together with ill-posedness of the underlying integral equation, this may significantly increase the dose nonuniformity. To optimize EUD and keep dose nonuniformity within reasonable limits, we implemented into an EUD-based objective function an additional criterion which ensures the smoothness of beam intensity functions. This approach is similar to the variational regularization technique which was previously studied for the dose-based least-squares optimization. We show that the variational regularization together with the L-curve criterion for the regularization parameter can significantly reduce dose nonuniformity in EUD-based inverse planning.

Dosimetric and geometric evaluation of a hybrid strategy of offline adaptive planning and online image guidance for prostate cancer radiotherapy

PubMed Central

Liu, Han; Wu, Qiuwen

2011-01-01

For prostate cancer patients, online image-guided (IG) radiotherapy has been widely used in clinic to correct the translational inter-fractional motion at each treatment fraction. For uncertainties that cannot be corrected online, such as rotation and deformation of the target volume, margins are still required to be added to the clinical target volume (CTV) for the treatment planning. Offline adaptive radiotherapy has been implemented to optimize the treatment for each individual patient based on the measurements at early stages of treatment process. It has been shown that offline adaptive radiotherapy can effectively reduce the required margin. Recently a hybrid strategy of offline adaptive replanning and online IG was proposed and the geometric evaluation was performed. It was found that the planning margins can be further reduced by 1–2 mm compared to online IG only strategy. The purpose of this study was to investigate the dosimetric benefits of such hybrid strategy on the target and organs at risk (OARs). A total of 420 repeated helical computed tomography (HCT) scans from 28 patients were included in the study. Both low-risk patients (LRP, CTV = prostate) and intermediate-risk patients (IRP, CTV = prostate + seminal vesicles, SV) were included in the simulation. Two registration methods, based on center-of-mass (COM) shift of prostate only and prostate plus SV, were performed for IRP. The intensity modulated radiotherapy (IMRT) was used in the simulation. Criteria on both cumulative dose and fractional doses were evaluated. Furthermore, the geometric evaluation was extended to investigate the optimal number of fractions necessary to construct the internal target volume (ITV) for the hybrid strategy. The dosimetric margin improvement was smaller than its geometric counterpart and was in the range of 0 mm to 1 mm. The optimal number of fractions necessary for the ITV construction is 2 for LRP and 3–4 for IRP in a hypofractionation protocol. A new cumulative index of target volume (CITV) was proposed for the evaluation of adaptive radiotherapy strategies, and it was found that it had the advantages over other indices in evaluating different adaptive radiotherapy strategies. PMID:21772083

Dosimetric and geometric evaluation of a hybrid strategy of offline adaptive planning and online image guidance for prostate cancer radiotherapy.

PubMed

Liu, Han; Wu, Qiuwen

2011-08-07

For prostate cancer patients, online image-guided (IG) radiotherapy has been widely used in clinic to correct the translational inter-fractional motion at each treatment fraction. For uncertainties that cannot be corrected online, such as rotation and deformation of the target volume, margins are still required to be added to the clinical target volume (CTV) for the treatment planning. Offline adaptive radiotherapy has been implemented to optimize the treatment for each individual patient based on the measurements at early stages of treatment process. It has been shown that offline adaptive radiotherapy can effectively reduce the required margin. Recently a hybrid strategy of offline adaptive replanning and online IG was proposed and the geometric evaluation was performed. It was found that the planning margins can further be reduced by 1-2 mm compared to online IG only strategy. The purpose of this study was to investigate the dosimetric benefits of such a hybrid strategy on the target and organs at risk. A total of 420 repeated helical computed tomography scans from 28 patients were included in the study. Both low-risk patients (LRP, CTV = prostate) and intermediate-risk patients (IRP, CTV = prostate + seminal vesicles, SV) were included in the simulation. Two registration methods, based on center-of-mass shift of prostate only and prostate plus SV, were performed for IRP. The intensity-modulated radiotherapy was used in the simulation. Criteria on both cumulative and fractional doses were evaluated. Furthermore, the geometric evaluation was extended to investigate the optimal number of fractions necessary to construct the internal target volume (ITV) for the hybrid strategy. The dosimetric margin improvement was smaller than its geometric counterpart and was in the range of 0-1 mm. The optimal number of fractions necessary for the ITV construction is 2 for LRPs and 3-4 for IRPs in a hypofractionation protocol. A new cumulative index of target volume was proposed for the evaluation of adaptive radiotherapy strategies, and it was found that it had the advantages over other indices in evaluating different adaptive radiotherapy strategies.

Conformal Radiotherapy in the Treatment of Advanced Juvenile Nasopharyngeal Angiofibroma With Intracranial Extension: An Institutional Experience

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

Chakraborty, Santam, E-mail: drsantam@gmail.com; Ghoshal, Sushmita; Patil, Vijay Maruti

2011-08-01

Purpose: To describe the results of conformal radiotherapy in advanced juvenile nasopharyngeal angiofibroma in a tertiary care institution. Methods and Materials: Retrospective chart review was conducted for 8 patients treated with conformal radiotherapy between 2006 and 2009. The median follow-up was 17 months. All patients had Stage IIIB disease with intracranial extension. Radiotherapy was considered as treatment because patients were deemed inoperable owing to extensive intracranial/intraorbital extension or proximity to optic nerve. All but 1 patient were treated with intensity-modulated radiotherapy using seven coplanar fields. Median (range) dose prescribed was 39.6 (30-46) Gy. Actuarial analysis of local control and descriptivemore » analysis of toxicity profile was conducted. Results: Despite the large and complex target volume (median planning target volume, 292 cm{sup 3}), intensity-modulated radiotherapy achieved conformal dose distributions (median van't Reit index, 0.66). Significant sparing of the surrounding organs at risk was obtained. No significant Grade 3/4 toxicities were experienced during or after treatment. Actual local control at 2 years was 87.5%. One patient died 1 month after radiotherapy secondary to massive epistaxis. The remaining 7 patients had progressive resolution of disease and were symptom-free at last follow-up. Persistent rhinitis was the only significant toxicity, seen in 1 patient. Conclusions: Conformal radiotherapy results in good local control with minimal acute and late side effects in juvenile nasopharyngeal angiofibromas, even in the presence of advanced disease.« less

Treatment planning, optimization, and beam delivery technqiues for intensity modulated proton therapy

NASA Astrophysics Data System (ADS)

Sengbusch, Evan R.

Physical properties of proton interactions in matter give them a theoretical advantage over photons in radiation therapy for cancer treatment, but they are seldom used relative to photons. The primary barriers to wider acceptance of proton therapy are the technical feasibility, size, and price of proton therapy systems. Several aspects of the proton therapy landscape are investigated, and new techniques for treatment planning, optimization, and beam delivery are presented. The results of these investigations suggest a means by which proton therapy can be delivered more efficiently, effectively, and to a much larger proportion of eligible patients. An analysis of the existing proton therapy market was performed. Personal interviews with over 30 radiation oncology leaders were conducted with regard to the current and future use of proton therapy. In addition, global proton therapy market projections are presented. The results of these investigations serve as motivation and guidance for the subsequent development of treatment system designs and treatment planning, optimization, and beam delivery methods. A major factor impacting the size and cost of proton treatment systems is the maximum energy of the accelerator. Historically, 250 MeV has been the accepted value, but there is minimal quantitative evidence in the literature that supports this standard. A retrospective study of 100 patients is presented that quantifies the maximum proton kinetic energy requirements for cancer treatment, and the impact of those results with regard to treatment system size, cost, and neutron production is discussed. This study is subsequently expanded to include 100 cranial stereotactic radiosurgery (SRS) patients, and the results are discussed in the context of a proposed dedicated proton SRS treatment system. Finally, novel proton therapy optimization and delivery techniques are presented. Algorithms are developed that optimize treatment plans over beam angle, spot size, spot spacing, beamlet weight, the number of delivered beamlets, and the number of delivery angles. These methods are evaluated via treatment planning studies including left-sided whole breast irradiation, lung stereotactic body radiotherapy, nasopharyngeal carcinoma, and whole brain radiotherapy with hippocampal avoidance. Improvements in efficiency and efficacy relative to traditional proton therapy and intensity modulated photon radiation therapy are discussed.

Evidence for the use PET for radiation therapy planning in patients with cervical cancer: a systematic review.

PubMed

Salem, A; Salem, A F; Al-Ibraheem, A; Lataifeh, I; Almousa, A; Jaradat, I

2011-01-01

In recent years, the role of positron emission tomography (PET) in the staging and management of gynecological cancers has been increasing. The aim of this study was to systematically review the role of PET in radiotherapy planning and brachytherapy treatment optimization in patients with cervical cancer. Systematic literature review. Systematic review of relevant literature addressing the utilization of PET and/or PET-computed tomography (CT) in external-beam radiotherapy planning and brachytherapy treatment optimization. We performed an extensive PubMed database search on 20 April 2011. Nineteen studies, including 759 patients, formed the basis of this systematic review. PET/ PET-CT is the most sensitive imaging modality for detecting nodal metastases in patients with cervical cancer and has been shown to impact external-beam radiotherapy planning by modifying the treatment field and customizing the radiation dose. This particularly applies to detection of previously uncovered para-aortic and inguinal nodal metastases. Furthermore, PET/ PET-CT guided intensity-modulated radiation therapy (IMRT) allows delivery of higher doses of radiation to the primary tumor, if brachytherapy is unsuitable, and to grossly involved nodal disease while minimizing treatment-related toxicity. PET/ PET-CT based brachytherapy optimization allows improved tumor-volume dose distribution and detailed 3D dosimetric evaluation of risk organs. Sequential PET/ PET-CT imaging performed during the course of brachytherapy form the basis of “adaptive” brachytherapy in cervical cancer. This review demonstrates the effectiveness of pretreatment PET/ PET-CT in cervical cancer patients treated by radiotherapy. Further prospective studies are required to define the group of patients who would benefit the most from this procedure.

Volumetric tumor burden and its effect on brachial plexus dosimetry in head and neck intensity-modulated radiotherapy

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

Romesser, Paul B.; Qureshi, Muhammad M.; Kovalchuk, Nataliya

2014-07-01

To determine the effect of gross tumor volume of the primary (GTV-P) and nodal (GTV-N) disease on planned radiation dose to the brachial plexus (BP) in head and neck intensity-modulated radiotherapy (IMRT). Overall, 75 patients underwent definitive IMRT to a median total dose of 69.96 Gy in 33 fractions. The right BP and left BP were prospectively contoured as separate organs at risk. The GTV was related to BP dose using the unpaired t-test. Receiver operating characteristics curves were constructed to determine optimized volumetric thresholds of GTV-P and GTV-N corresponding to a maximum BP dose cutoff of > 66 Gy.more » Multivariate analyses were performed to account for factors associated with a higher maximal BP dose. A higher maximum BP dose (> 66 vs ≤ 66 Gy) correlated with a greater mean GTV-P (79.5 vs 30.8 cc; p = 0.001) and ipsilateral GTV-N (60.6 vs 19.8 cc; p = 0.014). When dichotomized by the optimized nodal volume, patients with an ipsilateral GTV-N ≥ 4.9 vs < 4.9 cc had a significant difference in maximum BP dose (64.2 vs 59.4 Gy; p = 0.001). Multivariate analysis confirmed that an ipsilateral GTV-N ≥ 4.9 cc was an independent predictor for the BP to receive a maximal dose of > 66 Gy when adjusted individually for BP volume, GTV-P, the use of a low anterior neck field technique, total planned radiation dose, and tumor category. Although both the primary and the nodal tumor volumes affected the BP maximal dose, the ipsilateral nodal tumor volume (GTV-N ≥ 4.9 cc) was an independent predictor for high maximal BP dose constraints in head and neck IMRT.« less

Lung Cancer: Posttreatment Imaging: Radiation Therapy and Imaging Findings.

PubMed

Benveniste, Marcelo F; Welsh, James; Viswanathan, Chitra; Shroff, Girish S; Betancourt Cuellar, Sonia L; Carter, Brett W; Marom, Edith M

2018-05-01

In this review, we discuss the different radiation delivery techniques available to treat non-small cell lung cancer, typical radiologic manifestations of conventional radiotherapy, and different patterns of lung injury and temporal evolution of the newer radiotherapy techniques. More sophisticated techniques include intensity-modulated radiotherapy, stereotactic body radiotherapy, proton therapy, and respiration-correlated computed tomography or 4-dimensional computed tomography for radiotherapy planning. Knowledge of the radiation treatment plan and technique, the completion date of radiotherapy, and the temporal evolution of radiation-induced lung injury is important to identify expected manifestations of radiation-induced lung injury and differentiate them from tumor recurrence or infection. Published by Elsevier Inc.

Dosimetric Comparison of Intensity-Modulated Stereotactic Radiotherapy With Other Stereotactic Techniques for Locally Recurrent Nasopharyngeal Carcinoma

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

Kung, Shiris Wai Sum; Wu, Vincent Wing Cheung; Kam, Michael Koon Ming, E-mail: kamkm@yahoo.co

2011-01-01

Purpose: Locally recurrent nasopharyngeal carcinoma (NPC) patients can be salvaged by reirradiation with a substantial degree of radiation-related complications. Stereotactic radiotherapy (SRT) is widely used in this regard because of its rapid dose falloff and high geometric precision. The aim of this study was to examine whether the newly developed intensity-modulated stereotactic radiotherapy (IMSRT) has any dosimetric advantages over three other stereotactic techniques, including circular arc (CARC), static conformal beam (SmMLC), and dynamic conformal arc (mARC), in treating locally recurrent NPC. Methods and Materials: Computed tomography images of 32 patients with locally recurrent NPC, previously treated with SRT, were retrievedmore » from the stereotactic planning system for contouring and computing treatment plans. Treatment planning of each patient was performed for the four treatment techniques: CARC, SmMLC, mARC, and IMSRT. The conformity index (CI) and homogeneity index (HI) of the planning target volume (PTV) and doses to the organs at risk (OARs) and normal tissue were compared. Results: All four techniques delivered adequate doses to the PTV. IMSRT, SmMLC, and mARC delivered reasonably conformal and homogenous dose to the PTV (CI <1.47, HI <0.53), but not for CARC (p < 0.05). IMSRT presented with the smallest CI (1.37) and HI (0.40). Among the four techniques, IMSRT spared the greatest number of OARs, namely brainstem, temporal lobes, optic chiasm, and optic nerve, and had the smallest normal tissue volume in the low-dose region. Conclusion: Based on the dosimetric comparison, IMSRT was optimal for locally recurrent NPC by delivering a conformal and homogenous dose to the PTV while sparing OARs.« less

A modular approach to intensity-modulated arc therapy optimization with noncoplanar trajectories

NASA Astrophysics Data System (ADS)

Papp, Dávid; Bortfeld, Thomas; Unkelbach, Jan

2015-07-01

Utilizing noncoplanar beam angles in volumetric modulated arc therapy (VMAT) has the potential to combine the benefits of arc therapy, such as short treatment times, with the benefits of noncoplanar intensity modulated radiotherapy (IMRT) plans, such as improved organ sparing. Recently, vendors introduced treatment machines that allow for simultaneous couch and gantry motion during beam delivery to make noncoplanar VMAT treatments possible. Our aim is to provide a reliable optimization method for noncoplanar isocentric arc therapy plan optimization. The proposed solution is modular in the sense that it can incorporate different existing beam angle selection and coplanar arc therapy optimization methods. Treatment planning is performed in three steps. First, a number of promising noncoplanar beam directions are selected using an iterative beam selection heuristic; these beams serve as anchor points of the arc therapy trajectory. In the second step, continuous gantry/couch angle trajectories are optimized using a simple combinatorial optimization model to define a beam trajectory that efficiently visits each of the anchor points. Treatment time is controlled by limiting the time the beam needs to trace the prescribed trajectory. In the third and final step, an optimal arc therapy plan is found along the prescribed beam trajectory. In principle any existing arc therapy optimization method could be incorporated into this step; for this work we use a sliding window VMAT algorithm. The approach is demonstrated using two particularly challenging cases. The first one is a lung SBRT patient whose planning goals could not be satisfied with fewer than nine noncoplanar IMRT fields when the patient was treated in the clinic. The second one is a brain tumor patient, where the target volume overlaps with the optic nerves and the chiasm and it is directly adjacent to the brainstem. Both cases illustrate that the large number of angles utilized by isocentric noncoplanar VMAT plans can help improve dose conformity, homogeneity, and organ sparing simultaneously using the same beam trajectory length and delivery time as a coplanar VMAT plan.

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

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

Caglar, Hale B.; Tishler, Roy B.; Othus, Megan

2008-11-15

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

Proton Radiotherapy for Pediatric Bladder/Prostate Rhabdomyosarcoma: Clinical Outcomes and Dosimetry Compared to Intensity-Modulated Radiation Therapy

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

Cotter, Shane E.; Herrup, David A.; Friedmann, Alison

Purpose: In this study, we report the clinical outcomes of 7 children with bladder/prostate rhabdomyosarcoma (RMS) treated with proton radiation and compare proton treatment plans with matched intensity-modulated radiation therapy (IMRT) plans, with an emphasis on dose savings to reproductive and skeletal structures. Methods and Materials: Follow-up consisted of scheduled clinic appointments at our institution or direct communication with the treating physicians for referred patients. Each proton radiotherapy plan used for treatment was directly compared to an IMRT plan generated for the study. Clinical target volumes and normal tissue volumes were held constant to facilitate dosimetric comparisons. Each plan wasmore » optimized for target coverage and normal tissue sparing. Results: Seven male patients were treated with proton radiotherapy for bladder/prostate RMS at the Massachusetts General Hospital between 2002 and 2008. Median age at treatment was 30 months (11-70 months). Median follow-up was 27 months (10-90 months). Four patients underwent a gross total resection prior to radiation, and all patients received concurrent chemotherapy. Radiation doses ranged from 36 cobalt Gray equivalent (CGE) to 50.4 CGE. Five of 7 patients were without evidence of disease and with intact bladders at study completion. Target volume dosimetry was equivalent between the two modalities for all 7 patients. Proton radiotherapy led to a significant decrease in mean organ dose to the bladder (25.1 CGE vs. 33.2 Gy; p = 0.03), testes (0.0 CGE vs. 0.6 Gy; p = 0.016), femoral heads (1.6 CGE vs. 10.6 Gy; p = 0.016), growth plates (21.7 CGE vs. 32.4 Gy; p = 0.016), and pelvic bones (8.8 CGE vs. 13.5 Gy; p = 0.016) compared to IMRT. Conclusions: This study provides evidence of significant dose savings to normal structures with proton radiotherapy compared to IMRT and is well tolerated in this patient population. The long-term impact of these reduced doses can be tested in future studies incorporating extended follow-up, objective outcome measures, and quality-of-life analyses.« less

Automated planning of tangential breast intensity-modulated radiotherapy using heuristic optimization.

PubMed

Purdie, Thomas G; Dinniwell, Robert E; Letourneau, Daniel; Hill, Christine; Sharpe, Michael B

2011-10-01

To present an automated technique for two-field tangential breast intensity-modulated radiotherapy (IMRT) treatment planning. A total of 158 planned patients with Stage 0, I, and II breast cancer treated using whole-breast IMRT were retrospectively replanned using automated treatment planning tools. The tools developed are integrated into the existing clinical treatment planning system (Pinnacle(3)) and are designed to perform the manual volume delineation, beam placement, and IMRT treatment planning steps carried out by the treatment planning radiation therapist. The automated algorithm, using only the radio-opaque markers placed at CT simulation as inputs, optimizes the tangential beam parameters to geometrically minimize the amount of lung and heart treated while covering the whole-breast volume. The IMRT parameters are optimized according to the automatically delineated whole-breast volume. The mean time to generate a complete treatment plan was 6 min, 50 s ± 1 min 12 s. For the automated plans, 157 of 158 plans (99%) were deemed clinically acceptable, and 138 of 158 plans (87%) were deemed clinically improved or equal to the corresponding clinical plan when reviewed in a randomized, double-blinded study by one experienced breast radiation oncologist. In addition, overall the automated plans were dosimetrically equivalent to the clinical plans when scored for target coverage and lung and heart doses. We have developed robust and efficient automated tools for fully inversed planned tangential breast IMRT planning that can be readily integrated into clinical practice. The tools produce clinically acceptable plans using only the common anatomic landmarks from the CT simulation process as an input. We anticipate the tools will improve patient access to high-quality IMRT treatment by simplifying the planning process and will reduce the effort and cost of incorporating more advanced planning into clinical practice. Crown Copyright © 2011. Published by Elsevier Inc. All rights reserved.

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

NASA Astrophysics Data System (ADS)

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

2012-03-01

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

Helical tomotherapy to LINAC plan conversion utilizing RayStation Fallback planning.

PubMed

Zhang, Xin; Penagaricano, Jose; Narayanasamy, Ganesh; Corry, Peter; Liu, TianXiao; Sanjay, Maraboyina; Paudel, Nava; Morrill, Steven

2017-01-01

RaySearch RayStation Fallback (FB) planning module can generate an equivalent backup radiotherapy treatment plan facilitating treatment on other linear accelerators. FB plans were generated from the RayStation FB module by simulating the original plan target and organ at risk (OAR) dose distribution and delivered in various backup linear accelerators. In this study, helical tomotherapy (HT) backup plans used in Varian TrueBeam linear accelerator were generated with the RayStation FB module. About 30 patients, 10 with lung cancer, 10 with head and neck (HN) cancer, and 10 with prostate cancer, who were treated with HT, were included in this study. Intensity-modulated radiotherapy Fallback plans (FB-IMRT) were generated for all patients, and three-dimensional conformal radiotherapy Fallback plans (FB-3D) were only generated for lung cancer patients. Dosimetric comparison study evaluated FB plans based on dose coverage to 95% of the PTV volume (R 95 ), PTV mean dose (D mean ), Paddick's conformity index (CI), and dose homogeneity index (HI). The evaluation results showed that all IMRT plans were statistically comparable between HT and FB-IMRT plans except that PTV HI was worse in prostate, and PTV R 95 and HI were worse in HN multitarget plans for FB-IMRT plans. For 3D lung cancer plans, only the PTV R 95 was statistically comparable between HT and FB-3D plans, PTV D mean was higher, and CI and HI were worse compared to HT plans. The FB plans using a TrueBeam linear accelerator generally offer better OAR sparing compared to HT plans for all the patients. In this study, all cases of FB-IMRT plans and 9/10 cases of FB-3D plans were clinically acceptable without further modification and optimization once the FB plans were generated. However, the statistical differences between HT and FB-IMRT/3D plans might not be of any clinically significant. One FB-3D plan failed to simulate the original plan without further optimization. © 2017 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.

Late recurrence of nonseminomatous germ cell tumor successfully treated with intensity-modulated radiation therapy.

PubMed

Kita, Yuki; Imamura, Masaaki; Mizowaki, Takashi; Norihisa, Yoshiki; Yoshimura, Koji; Hiraoka, Masahiro; Ogawa, Osamu

2013-08-01

We report the case of a 41-year-old man with a late recurrence of nonseminomatous germ cell tumor, which was successfully treated with intensity-modulated radiation therapy. For the residual retrocrural tumor invading the 11th and 12th thoracic vertebrae with an abnormal level of tumor marker (α-fetoprotein: 23.2 ng/ml) after salvage chemotherapy, chemotherapy could not be continued due to its neurotoxicity, and surgery could not be performed due to the location. In this situation, intensity-modulated radiation therapy achieved a complete response of tumor marker. The patient remained in complete clinical remission after 3 years. The efficacy of radiotherapy, especially intensity-modulated radiation therapy, for a nonseminomatous germ cell tumor is discussed.

Radiotherapy of rectal cancer in elderly patients: Real-world data assessment in a decade.

PubMed

Diao, Peng; Langrand-Escure, Julien; Garcia, Max-Adrien; Espenel, Sophie; Rehailia-Blanchard, Amel; de Lavigerie, Blandine; Vial, Nicolas; de Laroche, Guy; Vallard, Alexis; Magné, Nicolas

2018-06-01

There is paucity of data on the efficacy and toxicity of radiotherapy in rectal cancer (RC) elderly patients. The objective was to identify management strategies and resulting outcomes in RC patients ≥70 years undergoing radiotherapy. A retrospective study included consecutive RC patients ≥70 years undergoing rectal radiotherapy. From 2004-2015, 340 RC patients underwent pre-operative (n = 238; 70%), post-operative (n = 41, 12%), or exclusive (n = 61, 18%) radiotherapy, with a median age of 78.5 years old (range: 70-96). Radiotherapy protocols were tailored, with 54 different radiotherapy programs (alteration of the total dose, and/or fractionation, and/or volume). Median follow-up was 27.1 months. Acute and late grade 3-4 radio-induced toxicities were reported in 3.5% and 0.9% of patients. Metastatic setting (OR = 6.60, CI95% 1.47-46.03, p = 0.02), exclusive radiotherapy (OR = 5.08, CI95% 1.48-18.21, p = 0.009), and intensity-modulated radiotherapy (OR = 6.42, CI95% 1.31-24.73, p = 0.01) were associated with grade ≥3 acute toxicities in univariate analysis. Exclusive radiotherapy (OR = 9.79, CI95% 2.49-43.18, p = 0.001) and intensity-modulated radiotherapy (OR = 12.62, CI95% 2.05-71.26, p = 0.003) were independent predictive factors of grade ≥3 acute toxicities in multivariate analysis. A complete pathological response was achieved in 12 out of 221 pre-operative patients (5.4%). Age, tumor stage, and surgery were independent predictive factors of survival in multivariate analysis. At end of follow-up, 7.1% of patients experienced local relapse. Radiotherapy for RC in elderly patients appeared safe and manageable, perhaps due to the tailoring of radiotherapy protocols. Tailored management resulted in acceptable rate of local tumor control. Copyright © 2018 Editrice Gastroenterologica Italiana S.r.l. Published by Elsevier Ltd. All rights reserved.

Cardiac Exposure in the Dynamic Conformal Arc Therapy, Intensity-Modulated Radiotherapy and Volumetric Modulated Arc Therapy of Lung Cancer

PubMed Central

Ming, Xin; Feng, Yuanming; Liu, Huan; Zhang, Ying; Zhou, Li; Deng, Jun

2015-01-01

Purpose To retrospectively evaluate the cardiac exposure in three cohorts of lung cancer patients treated with dynamic conformal arc therapy (DCAT), intensity-modulated radiotherapy (IMRT), or volumetric modulated arc therapy (VMAT) at our institution in the past seven years. Methods and Materials A total of 140 lung cancer patients were included in this institutional review board approved study: 25 treated with DCAT, 70 with IMRT and 45 with VMAT. All plans were generated in a same commercial treatment planning system and have been clinically accepted and delivered. The dose distribution to the heart and the effects of tumor laterality, the irradiated heart volume and the beam-to-heart distance on the cardiac exposure were investigated. Results The mean dose to the heart among all 140 plans was 4.5 Gy. Specifically, the heart received on average 2.3, 5.2 and 4.6 Gy in the DCAT, IMRT and VMAT plans, respectively. The mean heart doses for the left and right lung tumors were 4.1 and 4.8 Gy, respectively. No patients died with evidence of cardiac disease. Three patients (2%) with preexisting cardiac condition developed cardiac disease after treatment. Furthermore, the cardiac exposure was found to increase linearly with the irradiated heart volume while decreasing exponentially with the beam-to-heart distance. Conclusions Compared to old technologies for lung cancer treatment, modern radiotherapy treatment modalities demonstrated better heart sparing. But the heart dose in lung cancer radiotherapy is still higher than that in the radiotherapy of breast cancer and Hodgkin’s disease where cardiac complications have been extensively studied. With strong correlations of mean heart dose with beam-to-heart distance and irradiated heart volume, cautions should be exercised to avoid long-term cardiac toxicity in the lung cancer patients undergoing radiotherapy. PMID:26630566

Single-arc volumetric-modulated arc therapy (sVMAT) as adjuvant treatment for gastric cancer: Dosimetric comparisons with three-dimensional conformal radiotherapy (3D-CRT) and intensity-modulated radiotherapy (IMRT)

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

Wang, Xin; Li, Guangjun; Zhang, Yingjie

2013-01-01

To compare the dosimetric differences between the single-arc volumetric-modulated arc therapy (sVMAT), 3-dimensional conformal radiotherapy (3D-CRT), and intensity-modulated radiotherapy (IMRT) techniques in treatment planning for gastric cancer as adjuvant radiotherapy. Twelve patients were retrospectively analyzed. In each patient's case, the parameters were compared based on the dose-volume histogram (DVH) of the sVMAT, 3D-CRT, and IMRT plans, respectively. Three techniques showed similar target dose coverage. The maximum and mean doses of the target were significantly higher in the sVMAT plans than that in 3D-CRT plans and in the 3D-CRT/IMRT plans, respectively, but these differences were clinically acceptable. The IMRT and sVMATmore » plans successfully achieved better target dose conformity, reduced the V{sub 20/30}, and mean dose of the left kidney, as well as the V{sub 20/30} of the liver, compared with the 3D-CRT plans. And the sVMAT technique reduced the V{sub 20} of the liver much significantly. Although the maximum dose of the spinal cord were much higher in the IMRT and sVMAT plans, respectively (mean 36.4 vs 39.5 and 40.6 Gy), these data were still under the constraints. Not much difference was found in the analysis of the parameters of the right kidney, intestine, and heart. The IMRT and sVMAT plans achieved similar dose distribution to the target, but superior to the 3D-CRT plans, in adjuvant radiotherapy for gastric cancer. The sVMAT technique improved the dose sparings of the left kidney and liver, compared with the 3D-CRT technique, but showed few dosimetric advantages over the IMRT technique. Studies are warranted to evaluate the clinical benefits of the VMAT treatment for patients with gastric cancer after surgery in the future.« less

Intensity-Modulated Radiotherapy for Cervical Lymph Node Metastases From Unknown Primary Cancer

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

Madani, Indira; Vakaet, Luc; Bonte, Katrien

2008-07-15

Purpose: To compare the effectiveness of intensity-modulated radiotherapy (IMRT) and conventional (two-dimensional) radiotherapy in the treatment of cervical lymph node metastases from unknown primary cancer (UPC). Methods and Materials: Between February 2003 and September 2006, 23 patients with UPC of squamous cell carcinoma were treated with IMRT. Extended putative mucosal and bilateral nodal sites were irradiated to a median dose of 66 Gy. In 19 patients, IMRT was performed after lymph node dissection, and in 4 patients primary radiotherapy was given. The conventional radiotherapy group (historical control group) comprised 18 patients treated to a median dose of 66 Gy betweenmore » August 1994 and October 2003. Results: Twenty patients completed treatment. As compared with conventional radiotherapy, the incidence of Grade 3 acute dysphagia was significantly lower in the IMRT group (4.5% vs. 50%, p = 0.003). By 6 months, Grade 3 xerostomia was detected in 11.8% patients in the IMRT group vs. 53.4% in the historical control group (p = 0.03). No Grade 3 dysphagia or skin fibrosis was observed after IMRT but these were noted after conventional radiotherapy (26.7%, p = 0.01) and 26.7%, p = 0.03) respectively). With median follow-up of living patients of 17 months, there was no emergence of primary cancer. One patient had persistent nodal disease and another had nodal relapse at 5 months. Distant metastases were detected in 4 patients. The 2-year overall survival and distant disease-free probability after IMRT did not differ significantly from those for conventional radiotherapy (74.8% vs. 61.1% and 76.3% vs. 68.4%, respectively). Conclusions: Use of IMRT for UPC resulted in lower toxicity than conventional radiotherapy, and was similar in efficacy.« less

Dosimetric aspects of breast radiotherapy with three-dimensional and intensity-modulated radiotherapy helical tomotherapy planning modules

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

Yadav, Poonam; Service of Radiation Therapy, University of Wisconsin Aspirus Cancer Center, Wisconsin Rapids, WI; Yan, Yue, E-mail: yyan5@mdanderson.org

In this work, we investigated the dosimetric differences between the intensity-modulated radiotherapy (IMRT) plans and the three-dimensional (3D) helical plans based on the TomoTherapy system. A total of 15 patients with supine setup were randomly selected from the data base. For patients with lumpectomy planning target volume (PTV), regional lymph nodes were also included as part of the target. For dose sparing, the significant differences between the helical IMRT and helical 3D were only found in the heart and contralateral breast. For the dose to the heart, helical IMRT reduced the maximum point dose by 6.98 Gy compared to themore » helical 3D plan (p = 0.01). For contralateral breast, the helical IMRT plans significantly reduced the maximum point dose by 5.6 Gy compared to the helical 3D plan. However, compared to the helical 3D plan, the helical IMRT plan increased the volume for lower dose (13.08% increase in V{sub 5} {sub Gy}, p = 0.01). In general, there are no significant differences in dose sparing between helical IMRT and helical 3D plans.« less

Locoregional Control and Toxicity in Head and Neck Carcinoma Patients following Helical Tomotherapy-Delivered Intensity-Modulated Radiation Therapy Compared with 3D-CRT Data.

PubMed

Santa Cruz, Olalla; Tsoutsou, Pelagia; Castella, Cyril; Khanfir, Kaouthar; Anchisi, Sandro; Bouayed, Salim; Matzinger, Oscar; Ozsahin, Mahmut

2018-06-12

To assess the feasibility and efficacy of intensity-modulated radiation implemented with helical tomotherapy image-guided with daily megavoltage computed tomography for head and neck cancer. Between May 2010 and May 2013, 72 patients were treated with curative intent. The median age was 64 years, with 57% undergoing definitive and 43% postoperative radiotherapy. Primary tumour sites were oral cavity (21%), oropharynx (26%), hypopharynx (20%), larynx (22%), and others (11%). Staging included 4% stage I, 15% II, 26% III, 48% IVa, and 7% IVb. Radiotherapy was combined with chemotherapy in 64%. Primary endpoint was locoregional control, and secondary endpoints survival and toxicity. Median follow-up was 20 months, with 11 locoregional recurrences. Three-year disease-free survival was 58% and overall survival 57%. In the multivariate analysis, age under 64 years, no extracapsular extension, postoperative radiotherapy, induction chemotherapy, and non-oral cavity tumour were significant favourable prognostic factors for disease-free-survival. The overall incidence of acute grade ≥3 toxicities were mucositis 32%, pain 11%, xerostomia 7%, dysphagia 53%, radiodermatitis 44%, and osteonecrosis 1%. Late grade ≥3 toxicities were fibrosis 6%, dysphagia 21%, fistula 1%, and skin necrosis 1%. Intensity-modulated radiation with helical tomotherapy achieved respectable locoregional control and overall survival, with acceptable toxicity, in head and neck cancer patients. © 2018 S. Karger AG, Basel.

Dosimetric Evaluation of Intensity Modulated Radiotherapy and 4-Field 3-D Conformal Radiotherapy in Prostate Cancer Treatment

PubMed Central

Uysal, Bora; Beyzadeoğlu, Murat; Sager, Ömer; Dinçoğlan, Ferrat; Demiral, Selçuk; Gamsız, Hakan; Sürenkök, Serdar; Oysul, Kaan

2013-01-01

Objective: The purpose of this dosimetric study is the targeted dose homogeneity and critical organ dose comparison of 7-field Intensity Modulated Radiotherapy (IMRT) and 3-D 4-field conformal radiotherapy. Study Design: Cross sectional study. Material and Methods: Twenty patients with low and moderate risk prostate cancer treated at Gülhane Military Medical School Radiation Oncology Department between January 2009 and December 2009 are included in this study. Two seperate dosimetric plans both for 7-field IMRT and 3D-CRT have been generated for each patient to comparatively evaluate the dosimetric status of both techniques and all the patients received 7-field IMRT. Results: Dose-comparative evaluation of two techniques revealed the superiority of IMRT technique with statistically significantly lower femoral head doses along with reduced critical organ dose-volume parameters of bladder V60 (the volume receiving 60 Gy) and rectal V40 (the volume receiving 40 Gy) and V60. Conclusion: It can be concluded that IMRT is an effective definitive management tool for prostate cancer with improved critical organ sparing and excellent dose homogenization in target organs of prostate and seminal vesicles. PMID:25207069

Proof of Principle of Ocular sparing in dogs with sinonasal tumors treated with intensity-modulated radiation therapy

PubMed Central

Lawrence, Jessica A.; Forrest, Lisa J.; Turek, Michelle M.; Miller, Paul E.; Mackie, T. Rockwell; Jaradat, Hazim A.; Vail, David M.; Dubielzig, Richard R.; Chappell, Richard; Mehta, Minesh P.

2010-01-01

Intensity modulated radiation therapy (IMRT) allows optimization of radiation dose delivery to complex tumor volumes with rapid dose drop-off to surrounding normal tissues. A prospective study was performed to evaluate the concept of conformal avoidance using IMRT in canine sinonasal cancer. The potential of IMRT to improve clinical outcome with respect to acute and late ocular toxicity was evaluated. Thirty-one dogs with sinonasal cancer were treated definitively with IMRT using helical tomotherapy and/or dynamic multileaf collimator (DMLC) delivery. Ocular toxicity was evaluated prospectively and compared to a comparable group of historical controls treated with conventional two-dimensional radiotherapy (2D-RT) techniques. Treatment plans were devised for each dog using helical tomotherapy and DMLC that achieved the target dose to the planning treatment volume and limited critical normal tissues to the prescribed dose-volume constraints. Overall acute and late toxicities were limited and minor, detectable by an experienced observer. This was in contrast to the profound ocular morbidity observed in the historical control group treated with 2D-RT. Overall median survival for IMRT treated and 2D treated dogs was 420 days and 411 days, respectively. Compared with conventional techniques, IMRT reduced dose delivered to eyes and resulted in bilateral ocular sparing in the dogs reported herein. These data provide proof-of-principle that conformal avoidance radiotherapy can be delivered through high conformity IMRT, resulting in decreased normal tissue toxicity as compared to historical controls treated with 2D-RT. PMID:20973393

A technique for generating phase-space-based Monte Carlo beamlets in radiotherapy applications.

PubMed

Bush, K; Popescu, I A; Zavgorodni, S

2008-09-21

As radiotherapy treatment planning moves toward Monte Carlo (MC) based dose calculation methods, the MC beamlet is becoming an increasingly common optimization entity. At present, methods used to produce MC beamlets have utilized a particle source model (PSM) approach. In this work we outline the implementation of a phase-space-based approach to MC beamlet generation that is expected to provide greater accuracy in beamlet dose distributions. In this approach a standard BEAMnrc phase space is sorted and divided into beamlets with particles labeled using the inheritable particle history variable. This is achieved with the use of an efficient sorting algorithm, capable of sorting a phase space of any size into the required number of beamlets in only two passes. Sorting a phase space of five million particles can be achieved in less than 8 s on a single-core 2.2 GHz CPU. The beamlets can then be transported separately into a patient CT dataset, producing separate dose distributions (doselets). Methods for doselet normalization and conversion of dose to absolute units of Gy for use in intensity modulated radiation therapy (IMRT) plan optimization are also described.

Is "pelvic radiation disease" always the cause of bowel symptoms following prostate cancer intensity-modulated radiotherapy?

PubMed

Min, Myo; Chua, Benjamin; Guttner, Yvonne; Abraham, Ned; Aherne, Noel J; Hoffmann, Matthew; McKay, Michael J; Shakespeare, Thomas P

2014-02-01

Pelvic radiation disease (PRD) also widely known as "radiation proctopathy" is a well recognised late side-effect following conventional prostate radiotherapy. However, endoscopic evaluation and/or specialist referral for new or persistent post-prostate radiotherapy bowel symptoms is not routine and serious diagnoses may potentially be missed. Here we report a policy of endoscopic evaluation of bowel symptoms persisting >90 days post radiotherapy for prostate cancer. A consecutive series of 102 patients who had radical prostate intensity-modulated radiotherapy (IMRT)/image-guided radiotherapy (IGRT) and who had new or ongoing bowel symptoms or positive faecal occult blood tests (FOBT) on follow up visits more than three months after treatment, were referred for endoscopic examination. All but one (99%) had full colonoscopic investigation. Endoscopic findings included gastric/colonic/rectal polyps (56%), diverticular disease (49%), haemorrhoids (38%), radiation proctopathy (29%), gastritis/oesophagitis (8%) and rarer diagnoses, including bowel cancer which was found in 3%. Only four patients (4%) had radiation proctopathy without associated pathology and 65 patients (63%) had more than one diagnosis. If flexible sigmoidoscopy alone were used, 36.6% of patients and 46.6% patients with polyp(s) would have had their diagnoses missed. Our study has shown that bowel symptoms following prostate IMRT/IGRT are due to numerous diagnoses other than PRD, including malignancy. Routine referral pathways should be developed for endoscopic evaluation/specialist review for patients with new or persistent bowel symptoms (or positive FOBT) following prostate radiotherapy. This recommendation should be considered for incorporation into national guidelines. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Toxicity and dosimetric analysis of non-small cell lung cancer patients undergoing radiotherapy with 4DCT and image-guided intensity modulated radiotherapy: a regional centre's experience.

PubMed

Livingston, Gareth C; Last, Andrew J; Shakespeare, Thomas P; Dwyer, Patrick M; Westhuyzen, Justin; McKay, Michael J; Connors, Lisa; Leader, Stephanie; Greenham, Stuart

2016-09-01

For patients receiving radiotherapy for locally advance non-small cell lung cancer (NSCLC), the probability of experiencing severe radiation pneumonitis (RP) appears to rise with an increase in radiation received by the lungs. Intensity modulated radiotherapy (IMRT) provides the ability to reduce planned doses to healthy organs at risk (OAR) and can potentially reduce treatment-related side effects. This study reports toxicity outcomes and provides a dosimetric comparison with three-dimensional conformal radiotherapy (3DCRT). Thirty curative NSCLC patients received radiotherapy using four-dimensional computed tomography and five-field IMRT. All were assessed for early and late toxicity using common terminology criteria for adverse events. All plans were subsequently re-planned using 3DCRT to the same standard as the clinical plans. Dosimetric parameters for lungs, oesophagus, heart and conformity were recorded for comparison between the two techniques. IMRT plans achieved improved high-dose conformity and reduced OAR doses including lung volumes irradiated to 5-20 Gy. One case each of oesophagitis and erythema (3%) were the only Grade 3 toxicities. Rates of Grade 2 oesophagitis were 40%. No cases of Grade 3 RP were recorded and Grade 2 RP rates were as low as 3%. IMRT provides a dosimetric benefit when compared to 3DCRT. While the clinical benefit appears to increase with increasing target size and increasing complexity, IMRT appears preferential to 3DCRT in the treatment of NSCLC.

International Perspectives on Quality Assurance and New Techniques in Radiation Medicine: Outcomes of an IAEA Conference

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

Shortt, Ken; Davidsson, Lena; Hendry, Jolyon

2008-05-01

The International Atomic Energy Agency organized an international conference called, 'Quality Assurance and New Techniques in Radiation Medicine' (QANTRM). It dealt with quality assurance (QA) in all aspects of radiation medicine (diagnostic radiology, nuclear medicine, and radiotherapy) at the international level. Participants discussed QA issues pertaining to the implementation of new technologies and the need for education and staff training. The advantage of developing a comprehensive and harmonized approach to QA covering both the technical and the managerial issues was emphasized to ensure the optimization of benefits to patient safety and effectiveness. The necessary coupling between medical radiation imaging andmore » radiotherapy was stressed, particularly for advanced technologies. However, the need for a more systematic approach to the adoption of advanced technologies was underscored by a report on failures in intensity-modulated radiotherapy dosimetry auditing tests in the United States, which could imply inadequate implementation of QA for these new technologies. A plenary session addressed the socioeconomic impact of introducing advanced technologies in resource-limited settings. How shall the dual gaps, one in access to basic medical services and the other in access to high-quality modern technology, be addressed?.« less

International perspectives on quality assurance and new techniques in radiation medicine: outcomes of an IAEA conference.

PubMed

Shortt, Ken; Davidsson, Lena; Hendry, Jolyon; Dondi, Maurizio; Andreo, Pedro

2008-01-01

The International Atomic Energy Agency organized an international conference called, "Quality Assurance and New Techniques in Radiation Medicine" (QANTRM). It dealt with quality assurance (QA) in all aspects of radiation medicine (diagnostic radiology, nuclear medicine, and radiotherapy) at the international level. Participants discussed QA issues pertaining to the implementation of new technologies and the need for education and staff training. The advantage of developing a comprehensive and harmonized approach to QA covering both the technical and the managerial issues was emphasized to ensure the optimization of benefits to patient safety and effectiveness. The necessary coupling between medical radiation imaging and radiotherapy was stressed, particularly for advanced technologies. However, the need for a more systematic approach to the adoption of advanced technologies was underscored by a report on failures in intensity-modulated radiotherapy dosimetry auditing tests in the United States, which could imply inadequate implementation of QA for these new technologies. A plenary session addressed the socioeconomic impact of introducing advanced technologies in resource-limited settings. How shall the dual gaps, one in access to basic medical services and the other in access to high-quality modern technology, be addressed?

Predicting two-year longitudinal MD Anderson Dysphagia Inventory outcomes after intensity modulated radiotherapy for locoregionally advanced oropharyngeal carcinoma.

PubMed

Goepfert, Ryan P; Lewin, Jan S; Barrow, Martha P; Fuller, C David; Lai, Stephen Y; Song, Juhee; Hobbs, Brian P; Gunn, G Brandon; Beadle, Beth M; Rosenthal, David I; Garden, Adam S; Kies, Merrill S; Papadimitrakopoulou, Vali A; Schwartz, David L; Hutcheson, Katherine A

2017-04-01

To determine the factors associated with longitudinal patient-reported dysphagia as measured by the MD Anderson Dysphagia Inventory (MDADI) in locoregionally advanced oropharyngeal carcinoma (OPC) survivors treated with split-field intensity modulated radiotherapy (IMRT). Retrospective patient analysis. A retrospective analysis combined data from three single-institution clinical trials for stage III/IV head and neck carcinoma. According to trial protocols, patients had prospectively collected MDADI at baseline, 6, 12, and 24 months after treatment. OPC patients with baseline and at least one post-treatment MDADI were included. Longitudinal analysis was completed with multivariate linear mixed effects modeling. There were 116 patients who met inclusion criteria. Mean baseline MDADI composite was 88.3, dropping to 73.8 at 6 months, and rising to 78.6 and 83.3 by 12 and 24 months, respectively (compared to baseline, all P < .0001). Tumor stage and smoking status were significant predictors of longitudinal MDADI composite scores. Patients with T1, T2, and T3 tumors had 15.9 (P = .0001), 10.9 (P = .0049), and 7.5 (P = .0615), respectively, higher mean MDADI composite than those with T4 tumors, and current smokers had a 9.4 (P = .0007) lower mean MDADI composite than never smokers. Patients report clinically meaningful dysphagia early after split-field IMRT for locoregionally advanced OPC that remains apparent 6 months after treatment. MDADI scores recover slowly thereafter, but remain depressed at 24 months compared to baseline. Higher tumor stage and smoking status are important markers of patient-reported function through the course of treatment, suggesting these are important groups for heightened surveillance and more intensive interventions to optimize swallowing outcomes. 4 Laryngoscope, 127:842-848, 2017. © 2016 The American Laryngological, Rhinological and Otological Society, Inc.

Vector-model-supported optimization in volumetric-modulated arc stereotactic radiotherapy planning for brain metastasis

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

Liu, Eva Sau Fan; Department of Health Technology and Informatics, The Hong Kong Polytechnic University; Wu, Vincent Wing Cheung

Long planning time in volumetric-modulated arc stereotactic radiotherapy (VMA-SRT) cases can limit its clinical efficiency and use. A vector model could retrieve previously successful radiotherapy cases that share various common anatomic features with the current case. The prsent study aimed to develop a vector model that could reduce planning time by applying the optimization parameters from those retrieved reference cases. Thirty-six VMA-SRT cases of brain metastasis (gender, male [n = 23], female [n = 13]; age range, 32 to 81 years old) were collected and used as a reference database. Another 10 VMA-SRT cases were planned with both conventional optimization and vector-model-supported optimization, followingmore » the oncologists' clinical dose prescriptions. Planning time and plan quality measures were compared using the 2-sided paired Wilcoxon signed rank test with a significance level of 0.05, with positive false discovery rate (pFDR) of less than 0.05. With vector-model-supported optimization, there was a significant reduction in the median planning time, a 40% reduction from 3.7 to 2.2 hours (p = 0.002, pFDR = 0.032), and for the number of iterations, a 30% reduction from 8.5 to 6.0 (p = 0.006, pFDR = 0.047). The quality of plans from both approaches was comparable. From these preliminary results, vector-model-supported optimization can expedite the optimization of VMA-SRT for brain metastasis while maintaining plan quality.« less

Estimation of the risk of secondary malignancy arising from whole-breast irradiation: comparison of five radiotherapy modalities, including TomoHDA.

PubMed

Han, Eun Young; Paudel, Nava; Sung, Jiwon; Yoon, Myonggeun; Chung, Weon Kuu; Kim, Dong Wook

2016-04-19

The risk of secondary cancer from radiation treatment remains a concern for long-term breast cancer survivors, especially those treated with radiation at the age younger than 45 years. Treatment modalities optimally maximize the dose delivery to the tumor while minimizing radiation doses to neighboring organs, which can lead to secondary cancers. A new TomoTherapy treatment machine, TomoHDATM, can treat an entire breast with two static but intensity-modulated beams in a slice-by-slice fashion. This feature could reduce scattered and leakage radiation doses. We compared the plan quality and lifetime attributable risk (LAR) of a second malignancy among five treatment modalities: three-dimensional conformal radiation therapy, field-in-field forward-planned intensity-modulated radiation therapy, inverse-planned intensity-modulated radiation therapy (IMRT), volumetric modulated arc therapy, and TomoDirect mode on the TomoHDA system. Ten breast cancer patients were selected for retrospective analysis. Organ equivalent doses, plan characteristics, and LARs were compared. Out-of-field organ doses were measured with radio-photoluminescence glass dosimeters. Although the IMRT plan provided overall better plan quality, including the lowest probability of pneumonitis, it caused the second highest LAR. The TomoTherapy plan provided plan quality comparable to the IMRT plan and posed the lowest total LAR to neighboring organs. Therefore, it can be a better treatment modality for younger patients who have a longer life expectancy.

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

PubMed

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

2014-03-01

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

Compensators: An alternative IMRT delivery technique

PubMed Central

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

2004-01-01

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

Lowering Whole-Body Radiation Doses in Pediatric Intensity-Modulated Radiotherapy Through the Use of Unflattened Photon Beams;Flattening filter; Pediatric; Intensity-modulated radiotherapy; Second cancers; Radiation-induced malignancies

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

Cashmore, Jason, E-mail: Jason.cashmore@uhb.nhs.uk; Ramtohul, Mark; Ford, Dan

Purpose: Intensity modulated radiotherapy (IMRT) has been linked with an increased risk of secondary cancer induction due to the extra leakage radiation associated with delivery of these techniques. Removal of the flattening filter offers a simple way of reducing head leakage, and it may be possible to generate equivalent IMRT plans and to deliver these on a standard linear accelerator operating in unflattened mode. Methods and Materials: An Elekta Precise linear accelerator has been commissioned to operate in both conventional and unflattened modes (energy matched at 6 MV) and a direct comparison made between the treatment planning and delivery ofmore » pediatric intracranial treatments using both approaches. These plans have been evaluated and delivered to an anthropomorphic phantom. Results: Plans generated in unflattened mode are clinically identical to those for conventional IMRT but can be delivered with greatly reduced leakage radiation. Measurements in an anthropomorphic phantom at clinically relevant positions including the thyroid, lung, ovaries, and testes show an average reduction in peripheral doses of 23.7%, 29.9%, 64.9%, and 70.0%, respectively, for identical plan delivery compared to conventional IMRT. Conclusions: IMRT delivery in unflattened mode removes an unwanted and unnecessary source of scatter from the treatment head and lowers leakage doses by up to 70%, thereby reducing the risk of radiation-induced second cancers. Removal of the flattening filter is recommended for IMRT treatments.« less

Underestimation of Low-Dose Radiation in Treatment Planning of Intensity-Modulated Radiotherapy

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

Jang, Si Young; Liu, H. Helen; Mohan, Radhe

2008-08-01

Purpose: To investigate potential dose calculation errors in the low-dose regions and identify causes of such errors for intensity-modulated radiotherapy (IMRT). Methods and Materials: The IMRT treatment plans of 23 patients with lung cancer and mesothelioma were reviewed. Of these patients, 15 had severe pulmonary complications after radiotherapy. Two commercial treatment-planning systems (TPSs) and a Monte Carlo system were used to calculate and compare dose distributions and dose-volume parameters of the target volumes and critical structures. The effect of tissue heterogeneity, multileaf collimator (MLC) modeling, beam modeling, and other factors that could contribute to the differences in IMRT dose calculationsmore » were analyzed. Results: In the commercial TPS-generated IMRT plans, dose calculation errors primarily occurred in the low-dose regions of IMRT plans (<50% of the radiation dose prescribed for the tumor). Although errors in the dose-volume histograms of the normal lung were small (<5%) above 10 Gy, underestimation of dose <10 Gy was found to be up to 25% in patients with mesothelioma or large target volumes. These errors were found to be caused by inadequate modeling of MLC transmission and leaf scatter in commercial TPSs. The degree of low-dose errors depends on the target volumes and the degree of intensity modulation. Conclusions: Secondary radiation from MLCs contributes a significant portion of low dose in IMRT plans. Dose underestimation could occur in conventional IMRT dose calculations if such low-dose radiation is not properly accounted for.« less

Radiation therapy for breast cancer: Literature review

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

Balaji, Karunakaran, E-mail: karthik.balaji85@gmail.com; School of Advanced Sciences, VIT University, Vellore; Subramanian, Balaji

Concave shape with variable size target volume makes treatment planning for the breast/chest wall a challenge. Conventional techniques used for the breast/chest wall cancer treatment provided better sparing of organs at risk (OARs), with poor conformity and uniformity to the target volume. Advanced technologies such as intensity modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT) improve the target coverage at the cost of higher low dose volumes to OARs. Novel hybrid techniques present promising results in breast/chest wall irradiation in terms of target coverage as well as OARs sparing. Several published data compared these technologies for the benefit ofmore » the breast/chest wall with or without nodal volumes. The aim of this article is to review relevant data and identify the scope for further research in developing optimal treatment plan for breast/chest wall cancer treatment.« less

Adaptive Radiation for Lung Cancer

PubMed Central

Gomez, Daniel R.; Chang, Joe Y.

2011-01-01

The challenges of lung cancer radiotherapy are intra/inter-fraction tumor/organ anatomy/motion changes and the need to spare surrounding critical structures. Evolving radiotherapy technologies, such as four-dimensional (4D) image-based motion management, daily on-board imaging and adaptive radiotherapy based on volumetric images over the course of radiotherapy, have enabled us to deliver higher dose to target while minimizing normal tissue toxicities. The image-guided radiotherapy adapted to changes of motion and anatomy has made the radiotherapy more precise and allowed ablative dose delivered to the target using novel treatment approaches such as intensity-modulated radiation therapy, stereotactic body radiation therapy, and proton therapy in lung cancer, techniques used to be considered very sensitive to motion change. Future clinical trials using real time tracking and biological adaptive radiotherapy based on functional images are proposed. PMID:20814539

SU-E-T-175: Clinical Evaluations of Monte Carlo-Based Inverse Treatment Plan Optimization for Intensity Modulated Radiotherapy

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

Chi, Y; Li, Y; Tian, Z

2015-06-15

Purpose: Pencil-beam or superposition-convolution type dose calculation algorithms are routinely used in inverse plan optimization for intensity modulated radiation therapy (IMRT). However, due to their limited accuracy in some challenging cases, e.g. lung, the resulting dose may lose its optimality after being recomputed using an accurate algorithm, e.g. Monte Carlo (MC). It is the objective of this study to evaluate the feasibility and advantages of a new method to include MC in the treatment planning process. Methods: We developed a scheme to iteratively perform MC-based beamlet dose calculations and plan optimization. In the MC stage, a GPU-based dose engine wasmore » used and the particle number sampled from a beamlet was proportional to its optimized fluence from the previous step. We tested this scheme in four lung cancer IMRT cases. For each case, the original plan dose, plan dose re-computed by MC, and dose optimized by our scheme were obtained. Clinically relevant dosimetric quantities in these three plans were compared. Results: Although the original plan achieved a satisfactory PDV dose coverage, after re-computing doses using MC method, it was found that the PTV D95% were reduced by 4.60%–6.67%. After re-optimizing these cases with our scheme, the PTV coverage was improved to the same level as in the original plan, while the critical OAR coverages were maintained to clinically acceptable levels. Regarding the computation time, it took on average 144 sec per case using only one GPU card, including both MC-based beamlet dose calculation and treatment plan optimization. Conclusion: The achieved dosimetric gains and high computational efficiency indicate the feasibility and advantages of the proposed MC-based IMRT optimization method. Comprehensive validations in more patient cases are in progress.« less

Concurrent chemoradiotherapy versus radiotherapy alone for locoregionally advanced nasopharyngeal carcinoma in the era of intensity-modulated radiotherapy: a meta-analysis.

PubMed

He, Yan; Guo, Tao; Guan, Hui; Wang, Jingjing; Sun, Yu; Peng, Xingchen

2018-01-01

In this study, we attempted to compare the efficacy and toxicity of concurrent chemoradiotherapy (CCRT) with radiotherapy alone (RT) for locoregionally advanced nasopharyngeal carcinoma (LANPC) in the era of intensity-modulated radiotherapy (IMRT) by meta-analysis. We searched databases, and all randomized controlled trials meeting the inclusion criteria were utilized for a meta-analysis with RevMan 5.3 based on the Cochrane methodology. Fifteen studies were found suitable based on the inclusion criteria. CCRT not only significantly improved the overall response rate (risk ratio [RR]=0.53, 95% CI 0.43-0.66) and the complete response rate (RR=0.60, 95% CI 0.51-0.71) but also contributed to longer overall survival. The incidence of grade 3-4 adverse events from CCRT group increased in hematologic toxicity (RR 2.25, 95% CI 1.54-3.29), radiation-induced oral mucositis (RR 1.64, 95% CI 1.14-2.35), and radiodermatitis (RR 1.80, 95% CI 1.13-2.88). Compared with IMRT alone, CCRT provided survival benefit with acceptable toxicity in patients with LANPC. However, we need multicenter randomized controlled trials and long-term follow-up to evaluate the eventual efficacy and toxicity of concurrent chemotherapy plus IMRT.

SU-E-T-302: Dosimetric Comparison Between Volumetric Modulated Arc Radiotherapy and Intensity-Modulated Radiotherapy for Locally Recurrent Nasopharyngeal Carcinoma

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

Lu, J-Y; Huang, B-T; Zhang, J-Y

2015-06-15

Purpose: To compare volumetric modulated arc radiotherapy (VMAT) technique with fixed-gantry intensity-modulated radiotherapy (IMRT) technique for locally recurrent nasopharyngeal carcinoma. Methods: CT datasets of eleven nasopharyngeal-carcinoma patients were included. Dual-arc VMAT and seven-field IMRT plans were created for each case, and were then compared in terms of conformity index (CI), homogeneity index (HI) of the planning target volume (PTV), organ-at-risk (OAR) sparing, monitor unit (MU) and delivery time. Results: The D98% (near-minimal dose) of PTV in the VMAT plans was slightly lower than that of the IMRT plans (P < 0.05), while the CI was higher than that of themore » IMRT plans (P < 0.05). No significant difference was found in the HI between the two plans (P > 0.05). Compared with the IMRT plans, the VMAT plans demonstrated lower Dmean (mean dose) of the bilateral temporal lobes and the whole surrounding normal tissue (P < 0.05), but slightly higher Dmean of brainstem (P < 0.05). In terms of the other OARs, no significant differences were found (P > 0.05). The MUs of the VMAT plans (672 ± 112) was significantly lower than that of the IMRT plans (917 ± 206), by 25 ± 13% (P < 0.05). The average delivery time of the VMAT plans (2.3 ± 0.1 min) was less than that of the IMRT plans (5.1 ± 0.4 min), by 54 ± 3%. Conclusion: For locally recurrent nasopharyngeal carcinoma, the VMAT technique could achieve equivalent or superior dose distribution of the target and better protect the bilateral temporal lobes, compared with the IMRT technique. Moreover, it could reduce the MU and delivery time effectively.« less

Temporal lobe injury after re-irradiation of locally recurrent nasopharyngeal carcinoma using intensity modulated radiotherapy: clinical characteristics and prognostic factors.

PubMed

Liu, Shuai; Lu, Taixiang; Zhao, Chong; Shen, Jingxian; Tian, Yunming; Guan, Ying; Zeng, Lei; Xiao, Weiwei; Huang, Shaomin; Han, Fei

2014-09-01

Temporal lobe injury (TLI) is a debilitating complication after radiotherapy for nasopharyngeal carcinoma (NPC), especially in patients who suffer treatment relapses and receive re-irradiation. We explored the clinical characteristics and prognostic factors of TLI in locally recurrent NPC (rNPC) patients after re-irradiation using intensity modulated radiotherapy (IMRT). A total of 454 temporal lobes (TLs) from 227 locally rNPC patients were reviewed. The clinical characteristics of TLI were analyzed. In the two radiotherapy courses, the equivalent dose in 2 Gy per fraction (EQD2) for the TLs was recalculated to facilitate comparison of the individual data. The median follow-up time was 31 (range, 3-127) months. After re-irradiation using IMRT, 31.3 % (71/227) of patients developed TLI. The median latency of TLI was 15 (range, 4-100) months. Univariate and multivariate analysis showed that the interval time (IT) between the two courses of radiotherapy and the summation of the maximum doses of the two radiotherapy courses (EQD2 - ∑max) were independent factors influencing TLI. The 5-year incidence of TLI for an IT ≤26 or >26 months was 35.9 and 53.7 % respectively (p = 0.024). The median maximum doses delivered to the injured TLs were significantly higher than was the case for the uninjured TLs after two courses of radiotherapy (135.3 and 129.8 Gy, respectively: p < 0.001). The incidence of TLI with an EQD2 - ∑max < 125 Gy was <5 %, and with an EQD2 - ∑max <145 Gy it was <50 %. A treatment mode limiting EQD2 - ∑max <125 Gy with a >2-year interval was found to be relatively safe.

S-1 versus S-1 plus cisplatin concurrent intensity modulated radiation therapy in the treatment of esophageal squamous cell carcinoma: Study protocol for a randomized controlled phase II trial.

PubMed

Wen, Yixue; Zhao, Zhenhuan; Miao, Jidong; Yang, Qilin; Gui, Yan; Sun, Mingqiang; Tian, Honggang; Jia, Qiang; Liao, Dongbiao; Yang, Chen; Du, Xiaobo

2017-12-01

Chemotherapy regimens are often a 2-drug regimen in concurrent chemotherapy and radiotherapy for esophageal cancer (EC). However, some retrospective studies have suggested that for patients with EC receiving radiotherapy combined with 2-drug chemotherapy have the severe toxicity. And S-1 alone with the combination of radiotherapy treatment effect is good, and achieved good clinical remission rate. The purpose of this trial is compare the efficacy and toxicity of combining S-1 or S-1 plus cisplatin with radiotherapy for esophageal squamous cell carcinoma. The study is a randomized, controlled, multicenter trial, comparing S-1 versus S-1 plus cisplatin concurrent radiotherapy for patients with esophageal squamous cell carcinoma. Eighty-eight patients with unresectable or medically unfit for surgery esophageal squamous cell carcinoma (clinical stage I to III), will randomly assigned to receive four cycles (2 concomitant and 2 postradiotherapy) S-1 or S-1 plus cisplatin along with radiotherapy 60-66 Gy/30 to 33 fractions. The primary outcome is complete response rate of primary tumor which will be measured by endoscopy and computer screen at 3 months after the completion of treatment. Secondary outcomes include survival and toxicity. To our knowledge, this study protocol is the first to test the effect between S-1 versus S-1 plus cisplatin concurrent intensity modulated radiation therapy in the treatment of esophageal squamous cell carcinoma. If the result will be the same effect and fewer side effects and less costly in S-1 plus radiotherapy. It will supply more treatment selection for esophageal squamous cell carcinoma.

Acceleration of intensity-modulated radiotherapy dose calculation by importance sampling of the calculation matrices.

PubMed

Thieke, Christian; Nill, Simeon; Oelfke, Uwe; Bortfeld, Thomas

2002-05-01

In inverse planning for intensity-modulated radiotherapy, the dose calculation is a crucial element limiting both the maximum achievable plan quality and the speed of the optimization process. One way to integrate accurate dose calculation algorithms into inverse planning is to precalculate the dose contribution of each beam element to each voxel for unit fluence. These precalculated values are stored in a big dose calculation matrix. Then the dose calculation during the iterative optimization process consists merely of matrix look-up and multiplication with the actual fluence values. However, because the dose calculation matrix can become very large, this ansatz requires a lot of computer memory and is still very time consuming, making it not practical for clinical routine without further modifications. In this work we present a new method to significantly reduce the number of entries in the dose calculation matrix. The method utilizes the fact that a photon pencil beam has a rapid radial dose falloff, and has very small dose values for the most part. In this low-dose part of the pencil beam, the dose contribution to a voxel is only integrated into the dose calculation matrix with a certain probability. Normalization with the reciprocal of this probability preserves the total energy, even though many matrix elements are omitted. Three probability distributions were tested to find the most accurate one for a given memory size. The sampling method is compared with the use of a fully filled matrix and with the well-known method of just cutting off the pencil beam at a certain lateral distance. A clinical example of a head and neck case is presented. It turns out that a sampled dose calculation matrix with only 1/3 of the entries of the fully filled matrix does not sacrifice the quality of the resulting plans, whereby the cutoff method results in a suboptimal treatment plan.

Adaptive intensity modulated radiotherapy for advanced prostate cancer

NASA Astrophysics Data System (ADS)

Ludlum, Erica Marie

The purpose of this research is to develop and evaluate improvements in intensity modulated radiotherapy (IMRT) for concurrent treatment of prostate and pelvic lymph nodes. The first objective is to decrease delivery time while maintaining treatment quality, and evaluate the effectiveness and efficiency of novel one-step optimization compared to conventional two-step optimization. Both planning methods are examined at multiple levels of complexity by comparing the number of beam apertures, or segments, the amount of radiation delivered as measured by monitor units (MUs), and delivery time. One-step optimization is demonstrated to simplify IMRT planning and reduce segments (from 160 to 40), MUs (from 911 to 746), and delivery time (from 22 to 7 min) with comparable plan quality. The second objective is to examine the capability of three commercial dose calculation engines employing different levels of accuracy and efficiency to handle high--Z materials, such as metallic hip prostheses, included in the treatment field. Pencil beam, convolution superposition, and Monte Carlo dose calculation engines are compared by examining the dose differences for patient plans with unilateral and bilateral hip prostheses, and for phantom plans with a metal insert for comparison with film measurements. Convolution superposition and Monte Carlo methods calculate doses that are 1.3% and 34.5% less than the pencil beam method, respectively. Film results demonstrate that Monte Carlo most closely represents actual radiation delivery, but none of the three engines accurately predict the dose distribution when high-Z heterogeneities exist in the treatment fields. The final objective is to improve the accuracy of IMRT delivery by accounting for independent organ motion during concurrent treatment of the prostate and pelvic lymph nodes. A leaf-shifting algorithm is developed to track daily prostate position without requiring online dose calculation. Compared to conventional methods of adjusting patient position, adjusting the multileaf collimator (MLC) leaves associated with the prostate in each segment significantly improves lymph node dose coverage (maintains 45 Gy compared to 42.7, 38.3, and 34.0 Gy for iso-shifts of 0.5, 1 and 1.5 cm). Altering the MLC portal shape is demonstrated as a new and effective solution to independent prostate movement during concurrent treatment.

Xerostomia and quality of life after intensity-modulated radiotherapy vs. conventional radiotherapy for early-stage nasopharyngeal carcinoma: Initial report on a randomized controlled clinical trial

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

Pow, Edmond; Kwong, Dora; McMillan, Anne S.

2006-11-15

Purpose: To compare directly the effect of intensity-modulated radiotherapy (IMRT) vs. conventional radiotherapy (CRT) on salivary flow and quality of life (QoL) in patients with early-stage nasopharyngeal carcinoma (NPC). Methods and Materials: Fifty-one patients with T2, N0/N1, M0 NPC took part in a randomized controlled clinical study and received IMRT or CRT. Stimulated whole (SWS) and parotid (SPS) saliva flow were measured and Medical Outcomes Short Form 36 (SF-36), European Organization for Research and Treatment of Cancer (EORTC) core quetionnaire, and EORTC head-and-neck module (QLQ-H and N35) were completed at baseline and 2, 6, and 12 months after radiotherapy. Results:more » Forty-six patients (88%) were in disease remission 12 months after radiotherapy. At 12 months postradiotherapy, 12 (50.0%) and 20 patients (83.3%) in the IMRT group had recovered at least 25% of preradiotherapy SWS and SPS flow respectively, compared with 1 (4.8%) and 2 patients (9.5%), respectively, in the CRT group. Global health scores showed continuous improvement in QoL after both treatments (p < 0.001). However, after 12 months subscale scores for role-physical, bodily pain, and physical function were significantly higher in the IMRT group, indicating a better condition (p < 0.05). Dry mouth and sticky saliva were problems in both groups 2 months after treatment. In the IMRT group, there was consistent improvement over time with xerostomia-related symptoms significantly less common than in the CRT group at 12 months postradiotherapy. Conclusions: IMRT was significantly better than CRT in terms of parotid sparing and improved QoL for early-stage disease. The findings support the case for assessment of health-related QoL in relation to head-and-neck cancer using a site-specific approach.« less

SU-G-TeP1-05: Development and Clinical Introduction of Automated Radiotherapy Treatment Planning for Prostate Cancer

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

Winkel, D; Bol, GH; Asselen, B van

Purpose: To develop an automated radiotherapy treatment planning and optimization workflow for prostate cancer in order to generate clinical treatment plans. Methods: A fully automated radiotherapy treatment planning and optimization workflow was developed based on the treatment planning system Monaco (Elekta AB, Stockholm, Sweden). To evaluate our method, a retrospective planning study (n=100) was performed on patients treated for prostate cancer with 5 field intensity modulated radiotherapy, receiving a dose of 35×2Gy to the prostate and vesicles and a simultaneous integrated boost of 35×0.2Gy to the prostate only. A comparison was made between the dosimetric values of the automatically andmore » manually generated plans. Operator time to generate a plan and plan efficiency was measured. Results: A comparison of the dosimetric values show that automatically generated plans yield more beneficial dosimetric values. In automatic plans reductions of 43% in the V72Gy of the rectum and 13% in the V72Gy of the bladder are observed when compared to the manually generated plans. Smaller variance in dosimetric values is seen, i.e. the intra- and interplanner variability is decreased. For 97% of the automatically generated plans and 86% of the clinical plans all criteria for target coverage and organs at risk constraints are met. The amount of plan segments and monitor units is reduced by 13% and 9% respectively. Automated planning requires less than one minute of operator time compared to over an hour for manual planning. Conclusion: The automatically generated plans are highly suitable for clinical use. The plans have less variance and a large gain in time efficiency has been achieved. Currently, a pilot study is performed, comparing the preference of the clinician and clinical physicist for the automatic versus manual plan. Future work will include expanding our automated treatment planning method to other tumor sites and develop other automated radiotherapy workflows.« less

A Dosimetric Comparison of Proton and Intensity-Modulated Photon Radiotherapy for Pediatric Parameningeal Rhabdomyosarcomas

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

Kozak, Kevin R.; Adams, Judith; Krejcarek, Stephanie J.

Purpose: We compared tumor and normal tissue dosimetry of proton radiation therapy with intensity-modulated radiation therapy (IMRT) for pediatric parameningeal rhabdomyosarcomas (PRMS). Methods and Materials: To quantify dosimetric differences between contemporary proton and photon treatment for pediatric PRMS, proton beam plans were compared with IMRT plans. Ten patients treated with proton radiation therapy at Massachusetts General Hospital had IMRT plans generated. To facilitate dosimetric comparisons, clinical target volumes and normal tissue volumes were held constant. Plans were optimized for target volume coverage and normal tissue sparing. Results: Proton and IMRT plans provided acceptable and comparable target volume coverage, with atmore » least 99% of the CTV receiving 95% of the prescribed dose in all cases. Improved dose conformality provided by proton therapy resulted in significant sparing of all examined normal tissues except for ipsilateral cochlea and mastoid; ipsilateral parotid gland sparing was of borderline statistical significance (p = 0.05). More profound sparing of contralateral structures by protons resulted in greater dose asymmetry between ipsilateral and contralateral retina, optic nerves, cochlea, and mastoids; dose asymmetry between ipsilateral and contralateral parotids was of borderline statistical significance (p = 0.05). Conclusions: For pediatric PRMS, superior normal tissue sparing is achieved with proton radiation therapy compared with IMRT. Because of enhanced conformality, proton plans also demonstrate greater normal tissue dose distribution asymmetry. Longitudinal studies assessing the impact of proton radiotherapy and IMRT on normal tissue function and growth symmetry are necessary to define the clinical consequences of these differences.« less

Process-based quality management for clinical implementation of adaptive radiotherapy

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

Noel, Camille E.; Santanam, Lakshmi; Parikh, Parag J.

Purpose: Intensity-modulated adaptive radiotherapy (ART) has been the focus of considerable research and developmental work due to its potential therapeutic benefits. However, in light of its unique quality assurance (QA) challenges, no one has described a robust framework for its clinical implementation. In fact, recent position papers by ASTRO and AAPM have firmly endorsed pretreatment patient-specific IMRT QA, which limits the feasibility of online ART. The authors aim to address these obstacles by applying failure mode and effects analysis (FMEA) to identify high-priority errors and appropriate risk-mitigation strategies for clinical implementation of intensity-modulated ART. Methods: An experienced team of twomore » clinical medical physicists, one clinical engineer, and one radiation oncologist was assembled to perform a standard FMEA for intensity-modulated ART. A set of 216 potential radiotherapy failures composed by the forthcoming AAPM task group 100 (TG-100) was used as the basis. Of the 216 failures, 127 were identified as most relevant to an ART scheme. Using the associated TG-100 FMEA values as a baseline, the team considered how the likeliness of occurrence (O), outcome severity (S), and likeliness of failure being undetected (D) would change for ART. New risk priority numbers (RPN) were calculated. Failures characterized by RPN ≥ 200 were identified as potentially critical. Results: FMEA revealed that ART RPN increased for 38% (n = 48/127) of potential failures, with 75% (n = 36/48) attributed to failures in the segmentation and treatment planning processes. Forty-three of 127 failures were identified as potentially critical. Risk-mitigation strategies include implementing a suite of quality control and decision support software, specialty QA software/hardware tools, and an increase in specially trained personnel. Conclusions: Results of the FMEA-based risk assessment demonstrate that intensity-modulated ART introduces different (but not necessarily more) risks than standard IMRT and may be safely implemented with the proper mitigations.« less

Process-based quality management for clinical implementation of adaptive radiotherapy

PubMed Central

Noel, Camille E.; Santanam, Lakshmi; Parikh, Parag J.; Mutic, Sasa

2014-01-01

Purpose: Intensity-modulated adaptive radiotherapy (ART) has been the focus of considerable research and developmental work due to its potential therapeutic benefits. However, in light of its unique quality assurance (QA) challenges, no one has described a robust framework for its clinical implementation. In fact, recent position papers by ASTRO and AAPM have firmly endorsed pretreatment patient-specific IMRT QA, which limits the feasibility of online ART. The authors aim to address these obstacles by applying failure mode and effects analysis (FMEA) to identify high-priority errors and appropriate risk-mitigation strategies for clinical implementation of intensity-modulated ART. Methods: An experienced team of two clinical medical physicists, one clinical engineer, and one radiation oncologist was assembled to perform a standard FMEA for intensity-modulated ART. A set of 216 potential radiotherapy failures composed by the forthcoming AAPM task group 100 (TG-100) was used as the basis. Of the 216 failures, 127 were identified as most relevant to an ART scheme. Using the associated TG-100 FMEA values as a baseline, the team considered how the likeliness of occurrence (O), outcome severity (S), and likeliness of failure being undetected (D) would change for ART. New risk priority numbers (RPN) were calculated. Failures characterized by RPN ≥ 200 were identified as potentially critical. Results: FMEA revealed that ART RPN increased for 38% (n = 48/127) of potential failures, with 75% (n = 36/48) attributed to failures in the segmentation and treatment planning processes. Forty-three of 127 failures were identified as potentially critical. Risk-mitigation strategies include implementing a suite of quality control and decision support software, specialty QA software/hardware tools, and an increase in specially trained personnel. Conclusions: Results of the FMEA-based risk assessment demonstrate that intensity-modulated ART introduces different (but not necessarily more) risks than standard IMRT and may be safely implemented with the proper mitigations. PMID:25086527

Process-based quality management for clinical implementation of adaptive radiotherapy.

PubMed

Noel, Camille E; Santanam, Lakshmi; Parikh, Parag J; Mutic, Sasa

2014-08-01

Intensity-modulated adaptive radiotherapy (ART) has been the focus of considerable research and developmental work due to its potential therapeutic benefits. However, in light of its unique quality assurance (QA) challenges, no one has described a robust framework for its clinical implementation. In fact, recent position papers by ASTRO and AAPM have firmly endorsed pretreatment patient-specific IMRT QA, which limits the feasibility of online ART. The authors aim to address these obstacles by applying failure mode and effects analysis (FMEA) to identify high-priority errors and appropriate risk-mitigation strategies for clinical implementation of intensity-modulated ART. An experienced team of two clinical medical physicists, one clinical engineer, and one radiation oncologist was assembled to perform a standard FMEA for intensity-modulated ART. A set of 216 potential radiotherapy failures composed by the forthcoming AAPM task group 100 (TG-100) was used as the basis. Of the 216 failures, 127 were identified as most relevant to an ART scheme. Using the associated TG-100 FMEA values as a baseline, the team considered how the likeliness of occurrence (O), outcome severity (S), and likeliness of failure being undetected (D) would change for ART. New risk priority numbers (RPN) were calculated. Failures characterized by RPN ≥ 200 were identified as potentially critical. FMEA revealed that ART RPN increased for 38% (n = 48/127) of potential failures, with 75% (n = 36/48) attributed to failures in the segmentation and treatment planning processes. Forty-three of 127 failures were identified as potentially critical. Risk-mitigation strategies include implementing a suite of quality control and decision support software, specialty QA software/hardware tools, and an increase in specially trained personnel. Results of the FMEA-based risk assessment demonstrate that intensity-modulated ART introduces different (but not necessarily more) risks than standard IMRT and may be safely implemented with the proper mitigations.

Use of hydrogel spacer for improved rectal dose-sparing in patients undergoing radical radiotherapy for localized prostate cancer: First Canadian experience

PubMed Central

Berlin, Alejandro; Di Tomasso, Anne; Ballantyne, Heather; Patterson, Susan; Lam, Tony; Sundaramurthy, Aravind; Helou, Joelle; Bayley, Andrew; Chung, Peter

2017-01-01

We describe the initial experience using a hydrogel spacer (SpaceOAR) to separate the prostate-rectum interspace in patients planned to undergo radical hypofractionated, image-guided, intensity-modulated radiotherapy (IG-IMRT). We depict and discuss the impact of SpaceOAR in the context of hypofractionated IG-IMRT, and the particular considerations for its applications in the Canadian setting. PMID:29257741

Dosimetric comparison of helical tomotherapy, intensity-modulated radiation therapy, volumetric-modulated arc therapy, and 3-dimensional conformal therapy for the treatment of T1N0 glottic cancer

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

Ekici, Kemal, E-mail: drkemal06@hotmail.com; Pepele, Eda K.; Yaprak, Bahaddin

2016-01-01

Various radiotherapy planning methods for T1N0 laryngeal cancer have been proposed to decrease normal tissue toxicity. We compare helical tomotherapy (HT), linac-based intensity-modulated radiation therapy (IMRT), volumetric-modulated arc therapy (VMAT), and 3-D conformal radiotherapy (3D-CRT) techniques for T1N0 laryngeal cancer. Overall, 10 patients with T1N0 laryngeal cancer were selected and evaluated. Furthermore, 10 radiotherapy treatment plans have been created for all 10 patients, including HT, IMRT, VMAT, and 3D-CRT. IMRT, VMAT, and HT plans vs 3D-CRT plans consistently provided superior planning target volume (PTV) coverage. Similar target coverage was observed between the 3 IMRT modalities. Compared with 3D-CRT, IMRT, HT,more » and VMAT significantly reduced the mean dose to the carotid arteries. VMAT resulted in the lowest mean dose to the submandibular and thyroid glands. Compared with 3D-CRT, IMRT, HT, and VMAT significantly increased the maximum dose to the spinal cord It was observed that the 3 IMRT modalities studied showed superior target coverage with less variation between each plan in comparison with 3D-CRT. The 3D-CRT plans performed better at the D{sub max} of the spinal cord. Clinical investigation is warranted to determine if these treatment approaches would translate into a reduction in radiation therapy–induced toxicities.« less

Medical physics practice in the next decade

PubMed Central

Paliwal, Bhudatt

2006-01-01

Impressive advances in computers and materials science have fueled a broad-based confluence of basic science breakthroughs. These advances are making us reformulate our learning, teaching and credentialing methodologies and research and development frontiers. We are now in the age of molecular medicine. In the entire field of health care, a paradigm shift from population-based solutions to individual specific care is taking place. These trends are reshaping the practice of medical physics. In this short presentation, examples are given to illustrate developments in image-guided intensity-modulated and adaptive helical tomotherapy, enhanced application of intensity modulation radiotherapy (IMRT) using adaptive radiotherapy and conformal avoidance. These advances include improved normal tissue sparing and permit dose reconstruction and verification, thereby allowing significant biologically effective dose escalation and reduced radiation toxicity. The intrinsic capability of helical TomoTherapy for megavoltage CT imaging for IMRT image-guidance is also discussed. Finally developments in motion management are described. PMID:22275799

Use of stereotactic intensity-modulated radiotherapy in thyroid-related ophthalmopathy. Case report.

PubMed

Espinoza, Salvador; Saboori, Mehran; Forman, Scott; Moorthy, Chitti R; Benzil, Deborah L

2004-11-01

Thyroid-related ophthalmopathy (TRO), a debilitating condition involving a range of visual and orbital symptoms, occurs in up to 40% of patients with Graves disease. The goals of treatment include correcting thyroid dysfunction, relieving ocular pain, preserving vision, and improving cosmetic appearance. Options for therapy include symptomatic treatment, glucocorticoid medication, radiation therapy, and surgery. Traditional radiation treatment uses small opposed bilateral fields consisting of retrobulbar volumes and customized blocks to shield periorbital structures. The combination of intensity-modulated radiotherapy (IMRT) and stereotactic technology facilitates the administration of radiation to patients suffering from TRO and provides greater safety and efficacy than traditional treatment. The authors present the case of a patient with severe TRO whose symptoms resolved rapidly after treatment with stereotactic IMRT. The outcome in this case supports stereotactic IMRT as an effective treatment option for patients with TRO who also undergo radiation therapy.

Value of Intensity-Modulated Radiotherapy in Stage IV Head-and-Neck Squamous Cell Carcinoma

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

Dirix, Piet, E-mail: piet.dirix@uzleuven.b; Nuyts, Sandra

2010-12-01

Purpose: To review outcome and toxicity of Stage IVa and IVb head-and-neck squamous cell carcinoma patients treated with concomitant chemotherapy and intensity-modulated radiotherapy (IMRT) according to a hybrid fractionation schedule. Methods and Materials: Between 2006 and 2008, 42 patients with Stage IV head-and-neck squamous cell carcinoma were irradiated according to a hybrid fractionation schedule consisting of 20 fractions of 2 Gy (once daily), followed by 20 fractions of 1.6 Gy (twice daily), to a total dose of 72 Gy. Chemotherapy (cisplatinum, 100mg/m{sup 2}) was administered at the start of Weeks 1 and 4. Treatment outcome and toxicity were retrospectively comparedmore » with a previous patient group (n = 55), treated according to the same schedule, but without intensity modulation. Results: Locoregional control (LRC) and overall survival were 81% and 56% after 2 years, respectively. In comparison with the previous cohort, no significant differences were observed regarding either LRC (66%, p = 0.38) or overall survival (73%, p = 0.29). No Grade 4 or 5 toxicity was reported in the IMRT group, either acute or chronic. The use of IMRT significantly reduced the incidence of late Grade 2 or 3 xerostomia (52.9% vs. 90.2%, p < 0.001). No difference was observed regarding late Grade 2 or 3 dysphagia (p = 0.66). Conclusions: Intensity-modulated chemoradiotherapy does not compromise LRC and significantly reduces late toxicity, especially regarding xerostomia.« less

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

PubMed

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

2016-05-01

We examined the effects of intensity-modulated radiation therapy with dose-sparing and avoidance technique on a pediatric patient with localized intracranial germinoma. We also reviewed the literature regarding modern irradiation techniques in relation to late neurocognitive sequelae. A patient with a localized intracranial germinoma in the third ventricle anterior to the pineal gland received a dose-sparing intensity-modulated radiation therapy. The planning was compared to the radiation oncologist's guide of organs at risk and dose constraints for dosimetric analyses. The patient received radiation therapy alone. The total dose was 54Gy delivered in 2.0Gy fractions to the primary tumour and 37Gy in 1.4Gy fractions to whole ventricles using a dose-sculpting plan. Dosimetry analyses showed that dose-sparing intensity-modulated radiation therapy delivered reduced doses to the whole brain, temporal lobes, hippocampi, cochleae, and optic nerves. With a follow-up of 22 months, failure-free survival was 100% for the patient and no adverse events during radiation treatment process. Intensity-modulated radiation therapy with dose sparing and avoidance technique can spare the limbic circuit, central nervous system, and hippocampus for pineal germ cell tumours. This technique reduces the integral dose delivered to the uninvolved normal brain tissues and may reduce late neurocognitive sequelae caused by cranial radiotherapy. Copyright © 2016 Société française de radiothérapie oncologique (SFRO). Published by Elsevier SAS. All rights reserved.

SU-E-P-56: Dosimetric Comparison of Three Post Modified Radical Mastectomy Radiotherapy Techniques for Locally Advanced Left-Sided Breast Cancer and Beyond

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

Ma, C; Zhang, W; Lu, J

2015-06-15

Purpose: To compare the dosimetry of post modified radical mastectomy radiotherapy (PMRMRT) for left-sided breast cancer using 3-dimensional conformal radiotherapy (3DCRT), intensity-modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT). Methods: We created ten sets of PMRMRT plans for ten consecutive patients and utilized two tangential and one or two supraclavicular beams in 3DCRT, a total of 5 beams in IMRT and two optimized partial arcs in VMAT. The difference in results between any two of the three new plans, between new and previous 3DCRT plans were compared and analyzed by ANOVA (α =0.05) and paired-sample t-test respectively. Pmore » values less than 0.05 were considered statistically significant. Results: Both IMRT and VMAT plans had similar PTV coverage, hotspot area and conformity (all p>0.05), and significantly higher PTV coverage compared with new 3DCRT (both p<0.001). IMRT plans had significantly less heart and left lung radiation exposure compared with VMAT (all p<0.05). The 3DCRT plans with larger estimated CTV displacement had better target coverage but worse OARs sparing compared to those with smaller one. Conclusion: IMRT has dosimetrical advantages over the other two techniques in PMRMRT for left-sided breast cancer. Individually quantifying and minimizing CTV displacement can significantly improve dosage distribution. This work was supported by the Medical Scientific Research Foundation of Guangdong Procvince (A2014455 to Changchun Ma)« less

Intensity-modulated radiotherapy for localized nasopharyngeal amyloidosis : Case report and literature review.

PubMed

Luo, Ming; Peng, Gang; Shi, Liangliang; Ming, Xing; Li, Zhenyu; Fei, Shijiang; Ding, Qian; Cheng, Jing

2016-12-01

Primary localized amyloidosis is characterized by the deposition of amyloid proteins restricted to one organ, without systemic involvement. Primary nasopharyngeal amyloidosis is an exceedingly rare condition, for which the standard treatment remains unknown. Because of its challenging anatomical position, surgery alone hardly results in complete resection of the localized amyloidosis. Therefore, an interdisciplinary planning board to design optimal treatment is of particular importance. A 39-year-old man presented with a several-week history of nasal obstruction and epistaxis. Computed tomography (CT) and magnetic resonance imaging (MRI) revealed the presence of a retro-odontoid nonenhancing soft tissue mass. The endoscopic biopsy demonstrated that the mass was amyloid in nature. An extensive systemic workup revealed an absence of inflammatory process, systemic amyloidosis, or plasma cell dyscrasia. The patient was treated with a combination of surgery and radiotherapy, showing no evidence of recurrence or progression at his 1‑year follow-up. Primary solitary amyloidosis is a rare form of amyloidosis. To the best of our knowledge, this is the first report of a nasopharyngeal amyloidosis case treated with excision and radiation leading to complete remission. Because of the difficulty for surgeons to achieve radical resection with such lesions, radiotherapy proved to be an excellent adjuvant treatment in this case.

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

PubMed

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

2014-12-11

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

An Automated Treatment Plan Quality Control Tool for Intensity-Modulated Radiation Therapy Using a Voxel-Weighting Factor-Based Re-Optimization Algorithm.

PubMed

Song, Ting; Li, Nan; Zarepisheh, Masoud; Li, Yongbao; Gautier, Quentin; Zhou, Linghong; Mell, Loren; Jiang, Steve; Cerviño, Laura

2016-01-01

Intensity-modulated radiation therapy (IMRT) currently plays an important role in radiotherapy, but its treatment plan quality can vary significantly among institutions and planners. Treatment plan quality control (QC) is a necessary component for individual clinics to ensure that patients receive treatments with high therapeutic gain ratios. The voxel-weighting factor-based plan re-optimization mechanism has been proved able to explore a larger Pareto surface (solution domain) and therefore increase the possibility of finding an optimal treatment plan. In this study, we incorporated additional modules into an in-house developed voxel weighting factor-based re-optimization algorithm, which was enhanced as a highly automated and accurate IMRT plan QC tool (TPS-QC tool). After importing an under-assessment plan, the TPS-QC tool was able to generate a QC report within 2 minutes. This QC report contains the plan quality determination as well as information supporting the determination. Finally, the IMRT plan quality can be controlled by approving quality-passed plans and replacing quality-failed plans using the TPS-QC tool. The feasibility and accuracy of the proposed TPS-QC tool were evaluated using 25 clinically approved cervical cancer patient IMRT plans and 5 manually created poor-quality IMRT plans. The results showed high consistency between the QC report quality determinations and the actual plan quality. In the 25 clinically approved cases that the TPS-QC tool identified as passed, a greater difference could be observed for dosimetric endpoints for organs at risk (OAR) than for planning target volume (PTV), implying that better dose sparing could be achieved in OAR than in PTV. In addition, the dose-volume histogram (DVH) curves of the TPS-QC tool re-optimized plans satisfied the dosimetric criteria more frequently than did the under-assessment plans. In addition, the criteria for unsatisfied dosimetric endpoints in the 5 poor-quality plans could typically be satisfied when the TPS-QC tool generated re-optimized plans without sacrificing other dosimetric endpoints. In addition to its feasibility and accuracy, the proposed TPS-QC tool is also user-friendly and easy to operate, both of which are necessary characteristics for clinical use.

Hypothyroidism as a Consequence of Intensity-Modulated Radiotherapy With Concurrent Taxane-Based Chemotherapy for Locally Advanced Head-and-Neck Cancer

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

Diaz, Roberto; Jaboin, Jerry J.; Morales-Paliza, Manuel

Purpose: To conduct a retrospective review of 168 consecutively treated locally advanced head-and-neck cancer (LAHNC) patients treated with intensity-modulated radiotherapy (IMRT)/chemotherapy, to determine the rate and risk factors for developing hypothyroidism. Methods and Materials: Intensity-modulated radiotherapy was delivered in 33 daily fractions to 69.3 Gy to gross disease and 56.1 Gy to clinically normal cervical nodes. Dose-volume histograms (DVHs) of IMRT plans were used to determine radiation dose to thyroid and were compared with DVHs using conventional three-dimensional radiotherapy (3D-RT) in 10 of these same patients randomly selected for replanning and with DVHs of 16 patients in whom the thyroidmore » was intentionally avoided during IMRT. Weekly paclitaxel (30 mg/m{sup 2}) and carboplatin area under the curve-1 were given concurrently with IMRT. Results: Sixty-one of 128 evaluable patients (47.7%) developed hypothyroidism after a median of 1.08 years after IMRT (range, 2.4 months to 3.9 years). Age and volume of irradiated thyroid were associated with hypothyroidism development after IMRT. Compared with 3D-RT, IMRT with no thyroid dose constraints resulted in significantly higher minimum, maximum, and median dose (p < 0.0001) and percentage thyroid volume receiving 10, 20, and 60 Gy (p < 0.05). Compared with 3D-RT, IMRT with thyroid dose constraints resulted in lower median dose and percentage thyroid volume receiving 30, 40, and 50 Gy (p < 0.005) but higher minimum and maximum dose (p < 0.005). Conclusions: If not protected, IMRT for LAHNC can result in higher radiation to the thyroid than with conventional 3D-RT. Techniques to reduce dose and volume of radiation to thyroid tissue with IMRT are achievable and recommended.« less

Anal wall sparing effect of an endorectal balloon in 3D conformal and intensity-modulated prostate radiotherapy.

PubMed

Smeenk, Robert Jan; van Lin, Emile N J Th; van Kollenburg, Peter; Kunze-Busch, Martina; Kaanders, Johannes H A M

2009-10-01

To investigate the anal wall (Awall) sparing effect of an endorectal balloon (ERB) in 3D conformal radiotherapy (3D-CRT) and intensity-modulated radiotherapy (IMRT) for prostate cancer. In 24 patients with localized prostate carcinoma, two planning CT-scans were performed: with and without ERB. A prostate planning target volume (PTV) was defined, and the Awall was delineated, using two different methods. Three-field and 4-field 3D-CRT plans, and IMRT plans were generated with a prescription dose of 78Gy. In 144 treatment plans, the minimum dose (D(min)), maximum dose (D(max)), and mean dose (D(mean)) to the Awall were calculated, as well as the Awall volumes exposed to doses ranging from >or=20Gy to >or=70Gy (V(20)-V(70), respectively). In the 3D-CRT plans, an ERB significantly reduced D(mean), D(max), and V(30)-V(70). For IMRT all investigated dose parameters were significantly reduced by the ERB. The absolute reduction of D(mean) was 12Gy in 3D-CRT and was 7.5Gy in IMRT for both methods of Awall delineation. Application of an ERB showed a significant Awall sparing effect in both 3D-CRT and IMRT. This may lead to reduced late anal toxicity in prostate radiotherapy.

Clinical challenges in the implementation of a tomotherapy service for head and neck cancer patients in a regional UK radiotherapy centre.

PubMed

Chatterjee, S; Mott, J H; Smyth, G; Dickson, S; Dobrowsky, W; Kelly, C G

2011-04-01

Intensity-modulated radiotherapy (IMRT) is increasingly being used to treat head and neck cancer cases. We discuss the clinical challenges associated with the setting up of an image guided intensity modulated radiotherapy service for a subset of head and neck cancer patients, using a recently commissioned helical tomotherapy (HT) Hi Art (Tomotherapy Inc, WI) machine in this article. We also discuss the clinical aspects of the tomotherapy planning process, treatment and image guidance experiences for the first 10 head and neck cancer cases. The concepts of geographical miss along with tomotherapy-specific effects, including that of field width and megavoltage CT (MVCT) imaging strategy, have been highlighted using the first 10 head and neck cases treated. There is a need for effective streamlining of all aspects of the service to ensure compliance with cancer waiting time targets. We discuss how patient toxicity audits are crucial to guide refinement of the newly set-up planning dose constraints. This article highlights the important clinical issues one must consider when setting up a head and neck IMRT, image-guided radiotherapy service. It shares some of the clinical challenges we have faced during the setting up of a tomotherapy service. Implementation of a clinical tomotherapy service requires a multidisciplinary team approach and relies heavily on good team working and effective communication between different staff groups.

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

PubMed

Adams, E J; Warrington, A P

2008-04-01

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

Radical chemo-irradiation using intensity-modulated radiotherapy for locally advanced head and neck cancer in elderly patients: Experience from a tertiary care center in South India.

PubMed

Chalissery, J R; Sudheeran, P C; Varghese, K M; Venkatesan, K

2016-01-01

To assess the feasibility, tolerance and response of radical chemo irradiation using Intensity modulated Radiotherapy [IMRT] in elderly patients [age >65] with locally advanced head and neck cancer. Patients aged 65 and above [range 65 to 84years] registered in oncology outpatient unit in our institution between December 2011 to 2014, with stage III and IV head and neck cancer were treated with radical dose of radiotherapy using IMRT and concurrent chemotherapy with cisplatin 40mg/sq.m weekly. Response evaluation and toxicity profile assessment was done 6 to 8 weeks after completion of treatment and 3 monthly thereafter with median follow up of 3 years. Total number of patients analysed were 47. 43(91.5%) patients tolerated 66-.70Gy of radiotherapy and 4 or more cycles of weekly chemotherapy with cisplatin. First follow up evaluation at 6 to 8 weeks showed 81% patients having complete loco regional response. Grade III skin reaction and mucositis was noticed in 24% and 47% respectively. No grade III neutropenia observed. Median follow up of 3 years showed a complete local control in 53% and overall survival of 60%. Radical chemo irradiation with IMRT in elderly patients is a feasible option. Long term local control and overall survival benefits needs to be followed up.

Dosimetric studies of cadmium free alloy used in compensator based intensity modulated radiotherapy

NASA Astrophysics Data System (ADS)

Kaushik, Sandeep; Punia, Rajesh; Tyagi, Atul; Singh, Mann P.

2017-10-01

Aim of this study was to investigate dosimetric properties of cadmium free alloy which is used in compensator based intensity modulated radiotherapy (cIMRT). A mixture of lead, bismuth and tin was used to prepare the alloy whose melting point is 90-95 °C. Slabs of different thicknesses ranging from 0.71 cm to 6.14 cm were prepared. Density of alloy was measured by Archimedes' principle using water. For six megavolt (6 MV) photon beam energy transmission, linear effective attenuation coefficient (μeff), tissue phantom ratio (TPR1020), beam hardening, surface dose (Ds), percentage depth dose (PDD) and effect of scatter has been measured and analyzed for different field sizes and different thickness of compensator. Effect of extended source to detector distance (SDD) on transmissions and μeff was measured. The density of alloy was found to be 9.5456 g/cm3. At SDD of 100 cm, μeff was observed 0.4253 cm-1 for a field size of 10×10 cm 2. Calculated TPR1020 was found to be within 3% of experimental TPR1020 . It was found to be increasing with increasing thickness of compensator. Ds was found to decrease with thickness of compensator and increase with wider collimator opening due to increased scattered dose. Compensator slabs of 1 cm, 1.98 cm and 4.16 cm decreased surface dose by 4.2%, 6.1% and 9.5% respectively for a field size of 10×10 cm2 at 100 cm SDD. For small field size of 3×3 cm2 and 5×5 cm2 PDDs are increased from 3.0% to 5.5% of open beam PDDs as compensator thickness increased from 1 cm to 6.14 cm at a depth of 10 cm in water while variation in PDD is insignificant in for larger field sizes 10×10 cm2 to 20×20 cm2. A high degree of intensity modulation is essential in cIMRT and it can be achieved with this compensator material. Dosimetric properties analyzed in this study establish this alloy as a reliable, reusable, optimally dense and cost effective compensator material.

Planning magnetic resonance imaging for prostate cancer intensity-modulated radiation therapy: Impact on target volumes, radiotherapy dose and androgen deprivation administration.

PubMed

Horsley, Patrick J; Aherne, Noel J; Edwards, Grace V; Benjamin, Linus C; Wilcox, Shea W; McLachlan, Craig S; Assareh, Hassan; Welshman, Richard; McKay, Michael J; Shakespeare, Thomas P

2015-03-01

Magnetic resonance imaging (MRI) scans are increasingly utilized for radiotherapy planning to contour the primary tumors of patients undergoing intensity-modulated radiation therapy (IMRT). These scans may also demonstrate cancer extent and may affect the treatment plan. We assessed the impact of planning MRI detection of extracapsular extension, seminal vesicle invasion, or adjacent organ invasion on the staging, target volume delineation, doses, and hormonal therapy of patients with prostate cancer undergoing IMRT. The records of 509 consecutive patients with planning MRI scans being treated with IMRT for prostate cancer between January 2010 and July 2012 were retrospectively reviewed. Tumor staging and treatment plans before and after MRI were compared. Of the 509 patients, 103 (20%) were upstaged and 44 (9%) were migrated to a higher risk category as a result of findings at MRI. In 94 of 509 patients (18%), the MRI findings altered management. Ninety-four of 509 patients (18%) had a change to their clinical target volume (CTV) or treatment technique, and in 41 of 509 patients (8%) the duration of hormone therapy was changed because of MRI findings. The use of radiotherapy planning MRI altered CTV design, dose and/or duration of androgen deprivation in 18% of patients in this large, single institution series of men planned for dose-escalated prostate IMRT. This has substantial implications for radiotherapy target volumes and doses, as well as duration of androgen deprivation. Further research is required to investigate whether newer MRI techniques can simultaneously fulfill staging and radiotherapy contouring roles. © 2014 Wiley Publishing Asia Pty Ltd.

Mediastinal irradiation in a patient affected by lung carcinoma after heart transplantation: Helical tomotherapy versus three dimensional conformal radiotherapy.

PubMed

Giugliano, Francesca M; Iorio, Vincenzo; Cammarota, Fabrizio; Toledo, Diego; Senese, Rossana; Francomacaro, Ferdinando; Muto, Matteo; Muto, Paolo

2016-04-26

Patients who have undergone solid organ transplants are known to have an increased risk of neoplasia compared with the general population. We report our experience using mediastinal irradiation with helical tomotherapy versus three-dimensional conformal radiation therapy to treat a patient with lung carcinoma 15 years after heart transplantation. Our dosimetric evaluation showed no particular difference between the techniques, with the exception of some organs. Mediastinal irradiation after heart transplantation is feasible and should be considered after evaluation of the risk. Conformal radiotherapy or intensity-modulated radiotherapy appears to be the appropriate treatment in heart-transplanted oncologic patients.

[Rescue cryotherapy for prostate cancer after radiotherapy].

PubMed

García, Erique Lledó; Amo, Felipe Herranz; San Segundo, Carmen González; Fagundo, Eva Paños; Escudero, Roberto Molina; Alonso, Adrian Husillos; Piniés, Gabriel Ogaya; Rascón, Jose Jara; Fernández, Carlos Hernández

2012-01-01

Radical Radiotherapy constitutes a useful therapeutic option for localized prostate cancer. Almost one third of prostate cancer patients choose this alternative to treat the disease. Despite modifications in the technique as intensity modulation, 3D conformational radiotherapy or computer-assisted brachytherapy, a significant percentage of these patients will show an increase in PSA values after radiation. Local relapse without distant disease and PSA less than 10 ng/ml are candidates for salvage therapy. Cryotherapy has already become a curative treatment option in this group of patients. Recent technological as well as surgical advances in salvage-cryotherapy have reduced dramatically complications and progressively increase the interest on this alternative.

Protons in head-and-neck cancer: bridging the gap of evidence.

PubMed

Ramaekers, Bram L T; Grutters, Janneke P C; Pijls-Johannesma, Madelon; Lambin, Philippe; Joore, Manuela A; Langendijk, Johannes A

2013-04-01

To use Normal Tissue Complication Probability (NTCP) models and comparative planning studies to explore the (cost-)effectiveness of swallowing sparing intensity modulated proton radiotherapy (IMPT) compared with swallowing sparing intensity modulated radiotherapy with photons (IMRT) in head and neck cancer (HNC). A Markov model was constructed to examine and compare the costs and quality-adjusted life years (QALYs) of the following strategies: (1) IMPT for all patients; (2) IMRT for all patients; and (3) IMPT if efficient. The assumption of equal survival for IMPT and IMRT in the base case analysis was relaxed in a sensitivity analysis. Intensity modulated proton radiation therapy and IMRT for all patients yielded 6.620 and 6.520 QALYs and cost €50,989 and €41,038, respectively. Intensity modulated proton radiation therapy if efficient yielded 6.563 QALYs and cost €43,650. The incremental cost-effectiveness ratio of IMPT if efficient versus IMRT for all patients was €60,278 per QALY gained. In the sensitivity analysis, IMRT was more effective (0.967 QALYs) and less expensive (€8218) and thus dominated IMPT for all patients. Cost-effectiveness analysis based on normal tissue complication probability models and planning studies proved feasible and informative and enables the analysis of individualized strategies. The increased effectiveness of IMPT does not seem to outweigh the higher costs for all head-and-neck cancer patients. However, when assuming equal survival among both modalities, there seems to be value in identifying those patients for whom IMPT is cost-effective. Copyright © 2013 Elsevier Inc. All rights reserved.

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

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

Kimura, Tomoki, E-mail: tkkimura@hiroshima-u.ac.jp; Nishibuchi, Ikuno; Murakami, Yuji

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.more » 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.« less

Intensity-Modulated Radiotherapy of Head and Neck Cancer Aiming to Reduce Dysphagia: Early Dose-Effect Relationships for the Swallowing Structures

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

Feng, Felix Y.; Kim, Hyungjin M.; Lyden, Teresa H.

2007-08-01

Purpose: To present initial results of a clinical trial of intensity-modulated radiotherapy (IMRT) aiming to spare the swallowing structures whose dysfunction after chemoradiation is a likely cause of dysphagia and aspiration, without compromising target doses. Methods and Materials: This was a prospective, longitudinal study of 36 patients with Stage III-IV oropharyngeal (31) or nasopharyngeal (5) cancer. Definitive chemo-IMRT spared salivary glands and swallowing structures: pharyngeal constrictors (PC), glottic and supraglottic larynx (GSL), and esophagus. Lateral but not medial retropharyngeal nodes were considered at risk. Dysphagia endpoints included objective swallowing dysfunction (videofluoroscopy), and both patient-reported and observer-rated scores. Correlations between dosesmore » and changes in these endpoints from pre-therapy to 3 months after therapy were assessed. Results: Significant correlations were observed between videofluoroscopy-based aspirations and the mean doses to the PC and GSL, as well as the partial volumes of these structures receiving 50-65 Gy; the highest correlations were associated with doses to the superior PC (p = 0.005). All patients with aspirations received mean PC doses >60 Gy or PC V{sub 65} >50%, and GSL V{sub 50} >50%. Reduced laryngeal elevation and epiglottic inversion were correlated with mean PC and GSL doses (p < 0.01). All 3 patients with strictures had PC V{sub 70} >50%. Worsening patient-reported liquid swallowing was correlated with mean PC (p = 0.05) and esophageal (p 0.02) doses. Only mean PC doses were correlated with worsening patient-reported solid swallowing (p = 0.04) and observer-rated swallowing scores (p = 0.04). Conclusions: These dose-volume-effect relationships provide initial IMRT optimization goals and motivate further efforts to reduce swallowing structures doses to reduce dysphagia and aspiration.« less

Time management in radiation oncology: evaluation of time, attendance of medical staff, and resources during radiotherapy for prostate cancer: the DEGRO-QUIRO trial.

PubMed

Keilholz, L; Willner, J; Thiel, H-J; Zamboglou, N; Sack, H; Popp, W

2014-01-01

In order to evaluate resource requirements, the German Society of Radiation Oncology (DEGRO) recorded the times needed for core procedures in the radio-oncological treatment of various cancer types within the scope of its QUIRO trial. The present study investigated the personnel and infrastructural resources required in radiotherapy of prostate cancer. The investigation was carried out in the setting of definitive radiotherapy of prostate cancer patients between July and October 2008 at two radiotherapy centers, both with well-trained staff and modern technical facilities at their disposal. Personnel attendance times and room occupancy times required for core procedures (modules) were each measured prospectively by two independently trained observers using time measurements differentiated on the basis of professional group (physician, physicist, and technician), 3D conformal (3D-cRT), and intensity-modulated radiotherapy (IMRT). Total time requirements of 983 min for 3D-cRT and 1485 min for step-and-shoot IMRT were measured for the technician (in terms of professional group) in all modules recorded and over the entire course of radiotherapy for prostate cancer (72-76 Gy). Times needed for the medical specialist/physician were 255 min (3D-cRT) and 271 min (IMRT), times of the physicist were 181 min (3D-cRT) and 213 min (IMRT). The difference in time was significant, although variations in time spans occurred primarily as a result of various problems during patient treatment. This investigation has permitted, for the first time, a realistic estimation of average personnel and infrastructural requirements for core procedures in quality-assured definitive radiotherapy of prostate cancer. The increased time needed for IMRT applies to the step-and-shoot procedure with verification measurements for each irradiation planning.

Radiotherapy for gastric lymphoma: a planning study of 3D conformal radiotherapy, the half-beam method, and intensity-modulated radiotherapy.

PubMed

Inaba, Koji; Okamoto, Hiroyuki; Wakita, Akihisa; Nakamura, Satoshi; Kobayashi, Kazuma; Harada, Ken; Kitaguchi, Mayuka; Sekii, Shuhei; Takahashi, Kana; Yoshio, Kotaro; Murakami, Naoya; Morota, Madoka; Ito, Yoshinori; Sumi, Minako; Uno, Takashi; Itami, Jun

2014-11-01

During radiotherapy for gastric lymphoma, it is difficult to protect the liver and kidneys in cases where there is considerable overlap between these organs and the target volume. This study was conducted to compare the three radiotherapy planning techniques of four-fields 3D conformal radiotherapy (3DCRT), half-field radiotherapy (the half-beam method) and intensity-modulated radiotherapy (IMRT) used to treat primary gastric lymphoma in which the planning target volume (PTV) had a large overlap with the left kidney. A total of 17 patients with gastric diffuse large B-cell lymphoma (DLBCL) were included. In DLBCL, immunochemotherapy (Rituximab + CHOP) was followed by radiotherapy of 40 Gy to the whole stomach and peri-gastric lymph nodes. 3DCRT, the half-field method, and IMRT were compared with respect to the dose-volume histogram (DVH) parameters and generalized equivalent uniform dose (gEUD) to the kidneys, liver and PTV. The mean dose and gEUD for 3DCRT was higher than for IMRT and the half-beam method in the left kidney and both kidneys. The mean dose and gEUD of the left kidney was 2117 cGy and 2224 cGy for 3DCRT, 1520 cGy and 1637 cGy for IMRT, and 1100 cGy and 1357 cGy for the half-beam method, respectively. The mean dose and gEUD of both kidneys was 1335 cGy and 1559 cGy for 3DCRT, 1184 cGy and 1311 cGy for IMRT, and 700 cGy and 937 cGy for the half-beam method, respectively. Dose-volume histograms (DVHs) of the liver revealed a larger volume was irradiated in the dose range <25 Gy with 3DCRT, while the half-beam method irradiated a larger volume of liver with the higher dose range (>25 Gy). IMRT and the half-beam method had the advantages of dose reduction for the kidneys and liver. © The Author 2014. Published by Oxford University Press on behalf of The Japan Radiation Research Society and Japanese Society for Radiation Oncology.

Dosimetric comparison between proton beam therapy and photon radiation therapy for locally advanced non-small cell lung cancer.

PubMed

Wu, Chen-Ta; Motegi, Atsushi; Motegi, Kana; Hotta, Kenji; Kohno, Ryosuke; Tachibana, Hidenobu; Kumagai, Motoki; Nakamura, Naoki; Hojo, Hidehiro; Niho, Seiji; Goto, Koichi; Akimoto, Tetsuo

2016-08-10

To assess the feasibility of proton beam therapy for the patients with locally advanced non-small lung cancer. The dosimetry was analyzed retrospectively to calculate the doses to organs at risk, such as the lung, heart, esophagus and spinal cord. A dosimetric comparison between proton beam therapy and dummy photon radiotherapy (three-dimensional conformal radiotherapy) plans was performed. Dummy intensity-modulated radiotherapy plans were also generated for the patients for whom curative three-dimensional conformal radiotherapy plans could not be generated. Overall, 33 patients with stage III non-small cell lung cancer were treated with proton beam therapy between December 2011 and August 2014. The median age of the eligible patients was 67 years (range: 44-87 years). All the patients were treated with chemotherapy consisting of cisplatin/vinorelbine or carboplatin. The median prescribed dose was 60 GyE (range: 60-66 GyE). The mean normal lung V20 GyE was 23.6% (range: 14.9-32%), and the mean normal lung dose was 11.9 GyE (range: 6.0-19 GyE). The mean esophageal V50 GyE was 25.5% (range: 0.01-63.6%), the mean heart V40 GyE was 13.4% (range: 1.4-29.3%) and the mean maximum spinal cord dose was 40.7 GyE (range: 22.9-48 GyE). Based on dummy three-dimensional conformal radiotherapy planning, 12 patients were regarded as not being suitable for radical thoracic three-dimensional conformal radiotherapy. All the dose parameters of proton beam therapy, except for the esophageal dose, were lower than those for the dummy three-dimensional conformal radiotherapy plans. In comparison to the intensity-modulated radiotherapy plan, proton beam therapy also achieved dose reduction in the normal lung. None of the patients experienced grade 4 or worse non-hematological toxicities. Proton beam therapy for patients with stage III non-small cell lung cancer was feasible and was superior to three-dimensional conformal radiotherapy for several dosimetric parameters. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

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

PubMed

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

2016-04-15

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

Flattening filter-free accelerators: a report from the AAPM Therapy Emerging Technology Assessment Work Group.

PubMed

Xiao, Ying; Kry, Stephen F; Popple, Richard; Yorke, Ellen; Papanikolaou, Niko; Stathakis, Sotirios; Xia, Ping; Huq, Saiful; Bayouth, John; Galvin, James; Yin, Fang-Fang

2015-05-08

This report describes the current state of flattening filter-free (FFF) radiotherapy beams implemented on conventional linear accelerators, and is aimed primarily at practicing medical physicists. The Therapy Emerging Technology Assessment Work Group of the American Association of Physicists in Medicine (AAPM) formed a writing group to assess FFF technology. The published literature on FFF technology was reviewed, along with technical specifications provided by vendors. Based on this information, supplemented by the clinical experience of the group members, consensus guidelines and recommendations for implementation of FFF technology were developed. Areas in need of further investigation were identified. Removing the flattening filter increases beam intensity, especially near the central axis. Increased intensity reduces treatment time, especially for high-dose stereotactic radiotherapy/radiosurgery (SRT/SRS). Furthermore, removing the flattening filter reduces out-of-field dose and improves beam modeling accuracy. FFF beams are advantageous for small field (e.g., SRS) treatments and are appropriate for intensity-modulated radiotherapy (IMRT). For conventional 3D radiotherapy of large targets, FFF beams may be disadvantageous compared to flattened beams because of the heterogeneity of FFF beam across the target (unless modulation is employed). For any application, the nonflat beam characteristics and substantially higher dose rates require consideration during the commissioning and quality assurance processes relative to flattened beams, and the appropriate clinical use of the technology needs to be identified. Consideration also needs to be given to these unique characteristics when undertaking facility planning. Several areas still warrant further research and development. Recommendations pertinent to FFF technology, including acceptance testing, commissioning, quality assurance, radiation safety, and facility planning, are presented. Examples of clinical applications are provided. Several of the areas in which future research and development are needed are also indicated.

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

PubMed

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

2014-01-01

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

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

Beltran, C; Kamal, H

Purpose: To provide a multicriteria optimization algorithm for intensity modulated radiation therapy using pencil proton beam scanning. Methods: Intensity modulated radiation therapy using pencil proton beam scanning requires efficient optimization algorithms to overcome the uncertainties in the Bragg peaks locations. This work is focused on optimization algorithms that are based on Monte Carlo simulation of the treatment planning and use the weights and the dose volume histogram (DVH) control points to steer toward desired plans. The proton beam treatment planning process based on single objective optimization (representing a weighted sum of multiple objectives) usually leads to time-consuming iterations involving treatmentmore » planning team members. We proved a time efficient multicriteria optimization algorithm that is developed to run on NVIDIA GPU (Graphical Processing Units) cluster. The multicriteria optimization algorithm running time benefits from up-sampling of the CT voxel size of the calculations without loss of fidelity. Results: We will present preliminary results of Multicriteria optimization for intensity modulated proton therapy based on DVH control points. The results will show optimization results of a phantom case and a brain tumor case. Conclusion: The multicriteria optimization of the intensity modulated radiation therapy using pencil proton beam scanning provides a novel tool for treatment planning. Work support by a grant from Varian Inc.« less

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

PubMed

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

2014-05-08

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

SU-E-T-810: Volumetric Modulated Arc Therapy and Conventional Intensity-Modulated Radiotherapy for Non-Small-Cell Lung Cancer with Simultaneously Integrated Boost Radiation Therapy: A Planning Comparison Study

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

Liu, T; Chen, J; Zhang, G

2015-06-15

Purpose: To compare and analyze the characteristics of intensity-modulated arc therapy(IMAT) versus fixed-gantry intensity-modulated radiotherapy(IMRT) in treatment of non-small-cell lung cancer. Methods: Twelve patients treated in our radiotherapy center were selected for this study. The patient subsequently underwent 4D-CT simulation.Margins of 5mm and 10mm were added to the ITV to generate the CTV and PTV respectively. Three treatment plans (IMRT,one single arc (RA1),double arcs (RA2))were generated with Eclipse ver.8.6 planning systems. Using a dose level of 75Gy in 15fractions to the ITV,60Gy in 15fractions to the CTV and 45Gy in 15fractions to the PTV respectively. The target and normol tissuemore » volumes were compared,as were the dosimetry parameters. Results: There were no significant differences in CI of ITV,PTV,HI of ITV,CTV and PTV, V5,V10,V15,V20,V25,V30,V45,V50 of total-lung and mean lung dose (all p>0.05). However, the differences were significant in terms of CI of CTV,V5 of B-P (all p<0.05). On the MU, IMRT=1540MU,RA1=1006 MU and RA2=1096 MU. (F=12.00,P=0.000).On the treatment time, IMRT= 13.5min,RA1= 1.5min,and RA2=2.5 min (F= 30.11,P=0.000 ). Conclusion: IMAT is equal to IMRT in dosimetril evaluation. Due to much less Mu and delivery time,IMAT is an ideal technique in treating patients by reduceing the uncomfortable influnce which could effect the treatment.« less

Surface dose measurement with Gafchromic EBT3 film for intensity modulated radiotherapy technique

NASA Astrophysics Data System (ADS)

Akbas, Ugur; Kesen, Nazmiye Donmez; Koksal, Canan; Okutan, Murat; Demir, Bayram; Becerir, Hatice Bilge

2017-09-01

Accurate dose measurement in the buildup region is extremely difficult. Studies have reported that treatment planning systems (TPS) cannot calculate surface dose accurately. The aim of the study was to compare the film measurements and TPS calculations for surface dose in head and neck cancer treatment using intensity modulated radiation therapy (IMRT). IMRT plans were generated for 5 head and neck cancer patients by using Varian Eclipse TPS. Quality assurance (QA) plans of these IMRT plans were created on rando phantoms for surface dose measurements. EBT3 films were cut in size of 2.5 x 2.5 cm2 and placed on the left side, right side and the center of larynx and then the films were irradiated with 6 MV photon beams. The measured doses were compared with TPS. The results of TPS calculations were found to be lower compared to the EBT3 film measurements at all selected points. The lack of surface dose calculation in TPS should be considered while evaluating the radiotherapy plans.

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

Yu, V; Nguyen, D; Tran, A

Purpose: To develop and clinically implement 4π radiotherapy, an inverse optimization platform that maximally utilizes non-coplanar intensity modulated radiotherapy (IMRT) beams to significantly improve critical organ sparing. Methods: A 3D scanner was used to digitize the human and phantom subject surfaces, which were positioned in the computer assisted design (CAD) model of a TrueBeam machine to create a virtual geometrical model, based on which, the feasible beam space was calculated for different tumor locations. Beamlets were computed for all feasible beams using convolution/superposition. A column generation algorithm was employed to optimize patient specific beam orientations and fluence maps. Optimal routingmore » through all selected beams were calculated by a level set method. The resultant plans were converted to XML files and delivered to phantoms in the TrueBeam developer mode. Finally, 4π plans were recomputed in Eclipse and manually delivered to recurrent GBM patients. Results: Compared to IMRT utilizing manually selected beams and volumetric modulated arc therapy plans, markedly improved dosimetry was observed using 4π for the brain, head and neck, liver, lung, and prostate patients. The improvements were due to significantly improved conformality and reduced high dose spillage to organs mediolateral to the PTV. The virtual geometrical model was experimentally validated. Safety margins with 99.9% confidence in collision avoidance were included to the model based model accuracy estimates determined via 300 physical machine to phantom distance measurements. Automated delivery in the developer mode was completed in 10 minutes and collision free. Manual 4 π treatment on the GBM cases resulted in significant brainstem sparing and took 35–45 minutes including multiple images, which showed submillimeter cranial intrafractional motion. Conclusion: The mathematical modeling utilized in 4π is accurate to create and guide highly complex non-coplanar IMRT treatments that consistently and significantly outperform human-operator-created plans. Deliverability of such plans is clinically demonstrated. This work is funded by Varian Medical Systems and the NSF Graduate Research Fellowship DGE-1144087.« less

Volumetric Modulated Arc-Based Hypofractionated Stereotactic Radiotherapy for the Treatment of Selected Intracranial Arteriovenous Malformations: Dosimetric Report and Early Clinical Experience

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

Subramanian, Sai; Srinivas, Chilukuri; Ramalingam, K.

2012-03-01

Purpose: To evaluate, with a dosimetric and clinical feasibility study, RapidArc (a volumetric modulated arc technique) for hypofractionated stereotactic radiotherapy treatment of large arteriovenous malformations (AVMs). Methods and Materials: Nine patients were subject to multimodality imaging (magnetic resonance, computed tomography, and digital subtraction angiography) to determine nidus and target volumes, as well as involved organs at risk (optical structures, inner ear, brain stem). Plans for multiple intensity-modulated arcs with a single isocenter were optimized for a fractionation of 25 Gy in 5 fractions. All plans were optimized for 6-MV photon beams. Dose-volume histograms were analyzed to assess plan quality. Deliverymore » parameters were reported to appraise technical features of RapidArc, and pretreatment quality assurance measurements were carried out to report on quality of delivery. Results: Average size of AVM nidus was 26.2 cm{sup 3}, and RapidArc plans provided complete target coverage with minimal overdosage (V{sub 100%} = 100% and V{sub 110%} < 1%) and excellent homogeneity (<6%). Organs at risk were highly spared. The D{sub 1%} to chiasm, eyes, lenses, optic nerves, and brainstem (mean {+-} SD) was 6.4 {+-} 8.3, 1.9 {+-} 3.8, 2.3 {+-} 2.2, 0.7 {+-} 0.9, 4.4 {+-} 7.2, 12.2 {+-} 9.6 Gy, respectively. Conformity index (CI{sub 95%}) was 2.2 {+-} 0.1. The number of monitor units per gray was 277 {+-} 45, total beam-on time was 2.5 {+-} 0.3 min. Planning vs. delivery {gamma} pass rate was 98.3% {+-} 0.9%. None of the patients developed acute toxicity. With a median follow-up of 9 months, 3 patients presented with deterioration of symptoms and were found to have postradiation changes but responded symptomatically to steroids. These patients continue to do well on follow-up. One patient developed headache and seizures, which was attributed to intracranial bleed, confirmed on imaging. Conclusion: Hypofractionated stereotactic radiotherapy can be successfully delivered using the RapidArc form of volumetric arc technology for intracranial AVMs. The quality of delivery and calculated parameters are in agreement with each other and are in line with published reports for other sites.« less

Intensity-modulated radiation therapy: a review with a physics perspective.

PubMed

Cho, Byungchul

2018-03-01

Intensity-modulated radiation therapy (IMRT) has been considered the most successful development in radiation oncology since the introduction of computed tomography into treatment planning that enabled three-dimensional conformal radiotherapy in 1980s. More than three decades have passed since the concept of inverse planning was first introduced in 1982, and IMRT has become the most important and common modality in radiation therapy. This review will present developments in inverse IMRT treatment planning and IMRT delivery using multileaf collimators, along with the associated key concepts. Other relevant issues and future perspectives are also presented.

Coplanar intensity-modulated radiotherapy class solution for patients with prostate cancer with bilateral hip prostheses with and without nodal involvement

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

Lee, Young K., E-mail: Young.Lee@rmh.nhs.uk; McVey, Gerard P.; South, Chris P.

2013-07-01

Dose distributions for prostate radiotherapy are difficult to predict in patients with bilateral hip prostheses in situ, due to image distortions and difficulty in dose calculation. The feasibility of delivering curative doses to prostate using intensity-modulated radiotherapy (IMRT) in patients with bilateral hip prostheses was evaluated. Planning target volumes for prostate only (PTV1) and pelvic nodes (PTV2) were generated from data on 5 patients. PTV1 and PTV2 dose prescriptions were 70 Gy and 60 Gy, respectively, in 35 fractions, and an additional nodal boost of 65 Gy was added for 1 plan. Rectum, bladder, and bowel were also delineated. Beammore » angles and segments were chosen to best avoid entering through the prostheses. Dose-volume data were assessed with respect to clinical objectives. The plans achieved the required prescription doses to the PTVs. Five-field IMRT plans were adequate for patients with relatively small prostheses (head volumes<60 cm{sup 3}) but 7-field plans were required for patients with larger prostheses. Bowel and bladder doses were clinically acceptable for all patients. Rectal doses were deemed clinically acceptable, although the V{sub 50} {sub Gy} objective was not met for 4/5 patients. We describe an IMRT solution for patients with bilateral hip prostheses of varying size and shape, requiring either localized or whole pelvic radiotherapy for prostate cancer.« less

Prostate-specific antigen bounce after intensity-modulated radiotherapy for prostate cancer.

PubMed

Sheinbein, Courtney; Teh, Bin S; Mai, Wei Y; Grant, Walter; Paulino, Arnold; Butler, E Brian

2010-09-01

To report prostate-specific antigen (PSA) bounce in patients treated with intensity-modulated radiotherapy (IMRT) alone. Previous studies have reported PSA bounce in prostate cancer patients treated with conventional radiotherapy, 3D conformal radiotherapy, and permanent seed brachytherapy. From January 1997 to July 2002, 102 patients with clinically localized prostate cancer were treated with IMRT alone. No patients received androgen ablation. PSA bounce was defined as a PSA increase of at least 0.4 ng/mL, followed by any PSA decrease. Biochemical failure was defined by both the American Society for Therapeutic Radiology and Oncology 1996 and 2006 consensus definitions. The median follow-up was 76 months. The median length of time until the first PSA bounce was 13.6 months. Thirty-three patients (32.4%) had at least 1 PSA bounce, with 25 (24.5%) having 1 bounce; 6 (5.9%), 2 bounces; and 2 (2.0%), 4 bounces. PSA bounce was not significantly associated with biochemical no evidence of disease survival, clinical stage, pretreatment PSA, Gleason combined score, prostate planning target volume, PSA nadir, or mean dose to the prostate. The rate of PSA bounce in patients aged ≤ 70 and > 70 years was 44.4% and 22.8%, respectively (P = .032). Our patient series is the first report on PSA bounce in patients treated with IMRT. Our study confirms that the majority of patients with a bouncing PSA remain biochemically and clinically free of disease with extended follow-up. Copyright © 2010 Elsevier Inc. All rights reserved.

Clinical results of conformal versus intensity-modulated radiotherapy using a focal simultaneous boost for muscle-invasive bladder cancer in elderly or medically unfit patients.

PubMed

Lutkenhaus, Lotte J; van Os, Rob M; Bel, Arjan; Hulshof, Maarten C C M

2016-03-18

For elderly or medically unfit patients with muscle-invasive bladder cancer, cystectomy or chemotherapy are contraindicated. This leaves radical radiotherapy as the only treatment option. It was the aim of this study to retrospectively analyze the treatment outcome and associated toxicity of conformal versus intensity-modulated radiotherapy (IMRT) using a focal simultaneous tumor boost for muscle-invasive bladder cancer in patients not suitable for cystectomy. One hundred eighteen patients with T2-4 N0-1 M0 bladder cancer were analyzed retrospectively. Median age was 80 years. Treatment consisted of either a conformal box technique or IMRT and included a simultaneous boost to the tumor. To enable an accurate boost delivery, fiducial markers were placed around the tumor. Patients were treated with 40 Gy in 20 fractions to the elective treatment volumes, and a daily tumor boost up to 55-60 Gy. Clinical complete response was seen in 87 % of patients. Three-year overall survival was 44 %, with a locoregional control rate of 73 % at 3 years. Toxicity was low, with late urinary and intestinal toxicity rates grade ≥ 2 of 14 and 5 %, respectively. The use of IMRT reduced late intestinal toxicity, whereas fiducial markers reduced acute urinary toxicity. Radical radiotherapy using a focal boost is feasible and effective for elderly or unfit patients, with a 3-year locoregional control of 73 %. Toxicity rates were low, and were reduced by the use of IMRT and fiducial markers.

Volumetric-modulated arc therapy vs conventional fixed-field intensity-modulated radiotherapy in a whole-ventricular irradiation: A planning comparison study

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

Sakanaka, Katsuyuki; Mizowaki, Takashi, E-mail: mizo@kuhp.kyoto-u.ac.jp; Sato, Sayaka

This study evaluated the dosimetric difference between volumetric-modulated arc therapy (VMAT) and conventional fixed-field intensity-modulated radiotherapy (cIMRT) in whole-ventricular irradiation. Computed tomography simulation data for 13 patients were acquired to create plans for VMAT and cIMRT. In both plans, the same median dose (100% = 24 Gy) was prescribed to the planning target volume (PTV), which comprised a tumor bed and whole ventricles. During optimization, doses to the normal brain and body were reduced, provided that the dose constraints of the target coverage were satisfied. The dose-volume indices of the PTV, normal brain, and body as well as monitor unitsmore » were compared between the 2 techniques by using paired t-tests. The results showed no significant difference in the homogeneity index (0.064 vs 0.065; p = 0.824) of the PTV and conformation number (0.78 vs 0.77; p = 0.065) between the 2 techniques. In the normal brain and body, the dose-volume indices showed no significant difference between the 2 techniques, except for an increase in the volume receiving a low dose in VMAT; the absolute volume of the normal brain and body receiving 1 Gy of radiation significantly increased in VMAT by 1.6% and 8.3%, respectively, compared with that in cIMRT (1044 vs 1028 mL for the normal brain and 3079.2 vs 2823.3 mL for the body; p<0.001). The number of monitor units to deliver a 2.0-Gy fraction was significantly reduced in VMAT compared with that in cIMRT (354 vs 873, respectively; p<0.001). In conclusion, VMAT delivers IMRT to complex target volumes such as whole ventricles with fewer monitor units, while maintaining target coverage and conformal isodose distribution comparable to cIMRT; however, in addition to those characteristics, the fact that the volume of the normal brain and body receiving a low dose would increase in VMAT should be considered.« less

Intensity-modulated radiotherapy in the standard management of head and neck cancer: promises and pitfalls.

PubMed

Mendenhall, William M; Amdur, Robert J; Palta, Jatinder R

2006-06-10

The purpose of this article is to review the role of intensity-modulated radiotherapy (IMRT) in the standard management of patients with head and neck cancer through a critical review of the pertinent literature. IMRT may result in a dose distribution that is more conformal than that achieved with three-dimensional conformal radiotherapy (3D CRT), allowing dose reduction to normal structures and thus decreasing toxicity and possibly enhancing locoregional control through dose escalation. Disadvantages associated with IMRT include increased risk of a marginal miss, decreased dose homogeneity, increased total body dose, and increased labor and expense. Outcomes data after IMRT are limited, and follow-up is relatively short. Locoregional control rates appear to be comparable to those achieved with 3D CRT and, depending on the location and extent of the tumor, late toxicity may be lower. Despite limited data on clinical outcomes, IMRT has been widely adopted as a standard technique in routine practice and clinical trials. The use of IMRT involves a learning curve for the practitioner and will continue to evolve, requiring continuing education and monitoring of outcomes from routine practice. Additional standards pertaining to a variety of issues, including target definitions and dose specification, need to be developed. Phase III trials will better define the role of IMRT in coming years.

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

Dirix, Piet, E-mail: piet.dirix@uzleuven.b; Vanstraelen, Bianca; Jorissen, Mark

Purpose: To evaluate clinical outcome and toxicity of postoperative intensity-modulated radiotherapy (IMRT) for malignancies of the nasal cavity and paranasal sinuses. Methods and Materials: Between 2003 and 2008, 40 patients with cancer of the paranasal sinuses (n = 34) or nasal cavity (n = 6) received postoperative IMRT to a dose of 60 Gy (n = 21) or 66 Gy (n = 19). Treatment outcome and toxicity were retrospectively compared with that of a previous patient group (n = 41) who were also postoperatively treated to the same doses but with three-dimensional conformal radiotherapy without intensity modulation, from 1992 tomore » 2002. Results: Median follow-up was 30 months (range, 4-74 months). Two-year local control, overall survival, and disease-free survival were 76%, 89%, and 72%, respectively. Compared to the three-dimensional conformal radiotherapy treatment, IMRT resulted in significantly improved disease-free survival (60% vs. 72%; p = 0.02). No grade 3 or 4 toxicity was reported in the IMRT group, either acute or chronic. The use of IMRT significantly reduced the incidence of acute as well as late side effects, especially regarding skin toxicity, mucositis, xerostomia, and dry-eye syndrome. Conclusions: Postoperative IMRT for sinonasal cancer significantly improves disease-free survival and reduces acute as well as late toxicity. Consequently, IMRT should be considered the standard treatment modality for malignancies of the nasal cavity and paranasal sinuses.« less

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

PubMed

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

2009-07-01

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

Growth Of High-Cost Intensity-Modulated Radiotherapy For Prostate Cancer Raises Concerns About Overuse

PubMed Central

Jacobs, Bruce L.; Zhang, Yun; Skolarus, Ted A.; Hollenbeck, Brent K.

2012-01-01

To study the impact of new, expensive, and unproven therapies to treat prostate cancer, we investigated the dissemination of intensity-modulated radiotherapy (IMRT). IMRT is an innovative treatment for prostate cancer that delivers higher doses of radiation with improved precision compared to alternative radiotherapies. We observed rapid adoption of this new treatment among men diagnosed with prostate cancer from 2001 through 2007, despite uncertainty about its relative effectiveness. We compared patient and disease characteristics of those receiving IMRT and the previous radiation standard of care, three-dimensional conformal therapy; assessed intermediate-term outcomes; and examined potential factors associated with the increased use of IMRT. We found that in the early period of IMRT adoption (2001–03) men with high-risk disease were more likely to receive IMRT, whereas after IMRT’s initial dissemination (2004–07) men with low-risk disease had fairly similar likelihoods of receiving IMRT as men with high-risk disease. This raises concerns about overtreatment, as well as considerable health care costs, because treatment with IMRT costs $15,000–$20,000 more than other standard therapies. As health care delivery reforms gain traction, policy makers must balance the promotion of new, yet unproven, technology with the risk of overuse. PMID:22492892

Comparison of Toxicity Between Intensity-Modulated Radiotherapy and 3-Dimensional Conformal Radiotherapy for Locally Advanced Non-small-cell Lung Cancer.

PubMed

Ling, Diane C; Hess, Clayton B; Chen, Allen M; Daly, Megan E

2016-01-01

The role of intensity-modulated radiotherapy (IMRT) in reducing treatment-related toxicity for locally advanced non-small-cell lung cancer (NSCLC) remains incompletely defined. We compared acute toxicity and oncologic outcomes in a large cohort of patients treated with IMRT or 3-dimensional conformal radiotherapy (3-DCRT), with or without elective nodal irradiation (ENI). A single-institution retrospective review was performed evaluating 145 consecutive patients with histologically confirmed stage III NSCLC treated with definitive chemoradiotherapy. Sixty-five (44.8%) were treated with 3-DCRT using ENI, 43 (30.0%) with 3-DCRT using involved-field radiotherapy (IFRT), and 37 (25.5%) with IMRT using IFRT. All patients received concurrent chemotherapy. Comparison of acute toxicities by treatment technique (IMRT vs. 3-DCRT) and extent of nodal irradiation (3-DCRT-IFRT vs. 3-DCRT-ENI) was performed for grade 2 or higher esophagitis or pneumonitis, number of acute hospitalizations, incidence of opioid requirement, percutaneous endoscopic gastrostomy utilization, and percentage weight loss during treatment. Local control and overall survival were analyzed by the Kaplan-Meier method. We identified no significant differences in any measures of acute toxicity by treatment technique or extent of nodal irradiation. There was a trend toward lower rates of grade 2 or higher pneumonitis among IMRT patients compared to 3-DCRT patients (5.4% vs. 23.0%; P = .065). Local control and overall survival were similar between cohorts. Acute and subacute toxicities were similar for patients treated with IMRT and with 3-DCRT with or without ENI, with a nonsignificant trend toward a reduction in pneumonitis with IMRT. Larger studies are needed to better define which patients will benefit from IMRT. Copyright © 2016 Elsevier Inc. All rights reserved.

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

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

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

2010-11-15

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

Redesigning Radiotherapy Quality Assurance: Opportunities to Develop an Efficient, Evidence-Based System to Support Clinical Trials

PubMed Central

Bekelman, Justin E.; Deye, James A.; Vikram, Bhadrasain; Bentzen, Soren M.; Bruner, Deborah; Curran, Walter J.; Dignam, James; Efstathiou, Jason A.; FitzGerald, T. J.; Hurkmans, Coen; Ibbott, Geoffrey S.; Lee, J. Jack; Merchant, Timothy E.; Michalski, Jeff; Palta, Jatinder R.; Simon, Richard; Ten Haken, Randal K.; Timmerman, Robert; Tunis, Sean; Coleman, C. Norman; Purdy, James

2012-01-01

Background In the context of national calls for reorganizing cancer clinical trials, the National Cancer Institute (NCI) sponsored a two day workshop to examine the challenges and opportunities for optimizing radiotherapy quality assurance (QA) in clinical trial design. Methods Participants reviewed the current processes of clinical trial QA and noted the QA challenges presented by advanced technologies. Lessons learned from the radiotherapy QA programs of recent trials were discussed in detail. Four potential opportunities for optimizing radiotherapy QA were explored, including the use of normal tissue toxicity and tumor control metrics, biomarkers of radiation toxicity, new radiotherapy modalities like proton beam therapy, and the international harmonization of clinical trial QA. Results Four recommendations were made: 1) Develop a tiered (and more efficient) system for radiotherapy QA and tailor intensity of QA to clinical trial objectives. Tiers include (i) general credentialing, (ii) trial specific credentialing, and (iii) individual case review; 2) Establish a case QA repository; 3) Develop an evidence base for clinical trial QA and introduce innovative prospective trial designs to evaluate radiotherapy QA in clinical trials; and 4) Explore the feasibility of consolidating clinical trial QA in the United States. Conclusion Radiotherapy QA may impact clinical trial accrual, cost, outcomes and generalizability. To achieve maximum benefit, QA programs must become more efficient and evidence-based. PMID:22425219

Can Intensity-Modulated Radiotherapy Preserve Oral Health-Related Quality of Life of Nasopharyngeal Carcinoma Patients?

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

Pow, Edmond H.N., E-mail: ehnpow@hku.hk; Kwong, Dora L.W.; Sham, Jonathan S.T.

Purpose: To investigate the changes in salivary function and oral health-related quality of life for patients with nasopharyngeal carcinoma treated by intensity-modulated radiotherapy (IMRT). Methods and Materials: A total of 57 patients with early-stage nasopharyngeal carcinoma received IMRT. The parotid and whole saliva flow was measured, and the Medical Outcomes Study 36-item short form, European Organization for Research and Treatment of Cancer Quality of Life questionnaire-C30, European Organization for Research and Treatment of Cancer Quality of Life questionnaire 35-item head-and-neck module, and Oral Health Impact Profile questionnaires were completed at baseline and 2, 6, 12, 18, and 24 months aftermore » IMRT. Results: Parotid saliva flow recovered fully after 1 year and maintained. Whole saliva flow recovered partially to 40% of baseline. A general trend of deterioration in most quality of life scales was observed after IMRT, followed by gradual recovery. Persistent oral-related symptoms were found 2 years after treatment. Conclusion: IMRT for early-stage nasopharyngeal carcinoma could only partially preserve the whole salivary function and oral health-related quality of life.« less

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 abutting critical structures while minimizing dose to OARs. PMID:23800073

Direct aperture optimization using an inverse form of back-projection.

PubMed

Zhu, Xiaofeng; Cullip, Timothy; Tracton, Gregg; Tang, Xiaoli; Lian, Jun; Dooley, John; Chang, Sha X

2014-03-06

Direct aperture optimization (DAO) has been used to produce high dosimetric quality intensity-modulated radiotherapy (IMRT) treatment plans with fast treatment delivery by directly modeling the multileaf collimator segment shapes and weights. To improve plan quality and reduce treatment time for our in-house treatment planning system, we implemented a new DAO approach without using a global objective function (GFO). An index concept is introduced as an inverse form of back-projection used in the CT multiplicative algebraic reconstruction technique (MART). The index, introduced for IMRT optimization in this work, is analogous to the multiplicand in MART. The index is defined as the ratio of the optima over the current. It is assigned to each voxel and beamlet to optimize the fluence map. The indices for beamlets and segments are used to optimize multileaf collimator (MLC) segment shapes and segment weights, respectively. Preliminary data show that without sacrificing dosimetric quality, the implementation of the DAO reduced average IMRT treatment time from 13 min to 8 min for the prostate, and from 15 min to 9 min for the head and neck using our in-house treatment planning system PlanUNC. The DAO approach has also shown promise in optimizing rotational IMRT with burst mode in a head and neck test case.

Volumetric modulated arc therapy: a review of current literature and clinical use in practice

PubMed Central

Teoh, M; Clark, C H; Wood, K; Whitaker, S; Nisbet, A

2011-01-01

Volumetric modulated arc therapy (VMAT) is a novel radiation technique, which can achieve highly conformal dose distributions with improved target volume coverage and sparing of normal tissues compared with conventional radiotherapy techniques. VMAT also has the potential to offer additional advantages, such as reduced treatment delivery time compared with conventional static field intensity modulated radiotherapy (IMRT). The clinical worldwide use of VMAT is increasing significantly. Currently the majority of published data on VMAT are limited to planning and feasibility studies, although there is emerging clinical outcome data in several tumour sites. This article aims to discuss the current use of VMAT techniques in practice and review the available data from planning and clinical outcome studies in various tumour sites including prostate, pelvis (lower gastrointestinal, gynaecological), head and neck, thoracic, central nervous system, breast and other tumour sites. PMID:22011829

[Description of latest generation equipment in external radiotherapy].

PubMed

Pellejero, S; Lozares, S; Mañeru, F

2009-01-01

Both the planning systems and the form of administering radiotherapy have changed radically since the introduction of 3D planning. At present treatment planning based on computerised axial tomography (CAT) images is standard practice in radiotherapy services. In recent years lineal accelerators for medical use have incorporated technology capable of administering intensity modulated radiation beams (IMRT). With this mode distributions of conformed doses are generated that adjust to the three dimensional form of the white volume, providing appropriate coverage and a lower dose to nearby risk organs. The use of IMRT is rapidly spreading amongst radiotherapy centres throughout the world. This growing use of IMRT has focused attention on the need for greater control of the geometric uncertainties in positioning the patient and control of internal movements. To this end, both flat and volumetric image systems have been incorporated into the treatment equipment, making image-guided radiotherapy (IGRT) possible. This article offers a brief description of the latest advances included in the planning and administration of radiotherapy treatment.

A multicentre 'end to end' dosimetry audit of motion management (4DCT-defined motion envelope) in radiotherapy.

PubMed

Palmer, Antony L; Nash, David; Kearton, John R; Jafari, Shakardokht M; Muscat, Sarah

2017-12-01

External dosimetry audit is valuable for the assurance of radiotherapy quality. However, motion management has not been rigorously audited, despite its complexity and importance for accuracy. We describe the first end-to-end dosimetry audit for non-SABR (stereotactic ablative body radiotherapy) lung treatments, measuring dose accumulation in a moving target, and assessing adequacy of target dose coverage. A respiratory motion lung-phantom with custom-designed insert was used. Dose was measured with radiochromic film, employing triple-channel dosimetry and uncertainty reduction. The host's 4DCT scan, outlining and planning techniques were used. Measurements with the phantom static and then moving at treatment delivery separated inherent treatment uncertainties from motion effects. Calculated and measured dose distributions were compared by isodose overlay, gamma analysis, and we introduce the concept of 'dose plane histograms' for clinically relevant interpretation of film dosimetry. 12 radiotherapy centres and 19 plans were audited: conformal, IMRT (intensity modulated radiotherapy) and VMAT (volumetric modulated radiotherapy). Excellent agreement between planned and static-phantom results were seen (mean gamma pass 98.7% at 3% 2 mm). Dose blurring was evident in the moving-phantom measurements (mean gamma pass 88.2% at 3% 2 mm). Planning techniques for motion management were adequate to deliver the intended moving-target dose coverage. A novel, clinically-relevant, end-to-end dosimetry audit of motion management strategies in radiotherapy is reported. Copyright © 2017 Elsevier B.V. All rights reserved.

Dosimetric and efficiency comparison of high-dose radiotherapy for esophageal cancer: volumetric modulated arc therapy versus fixed-field intensity-modulated radiotherapy.

PubMed

Lin, C-Y; Huang, W-Y; Jen, Y-M; Chen, C-M; Su, Y-F; Chao, H-L; Lin, C-S

2014-08-01

The aim of this study was to compare high-dose volumetric modulated arc therapy (VMAT) and fixed-field intensity-modulated radiotherapy (ff-IMRT) plans for the treatment of patients with middle-thoracic esophageal cancer. Eight patients with cT2-3N0M0 middle-thoracic esophageal cancer were enrolled. The treatment planning system was the version 9 of the Pinnacle(3) with SmartArc (Philips Healthcare, Fitchburg, WI, USA). VMAT and ff-IMRT treatment plans were generated for each case, and both techniques were used to deliver 50 Gy to the planning target volume (PTV(50)) and then provided a 16-Gy boost (PTV(66)). The VMAT plans provided superior PTV(66) coverage compared with the ff-IMRT plans (P = 0.034), whereas the ff-IMRT plans provided more appropriate dose homogeneity to the PTV(50) (P = 0.017). In the lung, the V(5) and V(10) were lower for the ff-IMRT plans than for the VMAT plans, whereas the V(20) was lower for the VMAT plans. The delivery time was significantly shorter for the VMAT plans than for the ff-IMRT plans (P = 0.012). In addition, the VMAT plans delivered fewer monitor units. The VMAT technique required a shorter planning time than the ff-IMRT technique (3.8 ± 0.8 hours vs. 5.4 ± 0.6 hours, P = 0.011). The major advantages of VMAT plans are higher efficiency and an approximately 50% reduction in delivery time compared with the ff-IMRT plans, with comparable plan quality. Further clinical investigations to evaluate the use of high-dose VMAT for the treatment of esophageal cancer are warranted. © 2013 Wiley Periodicals, Inc. and the International Society for Diseases of the Esophagus.

SU-E-P-51: Dosimetric Comparison to Organs at Risk Sparing Using Volumetric-Modulated Arc Therapy Versus Intensity-Modulated Radiotherapy in Postoperative Radiotherapy of Left-Sided Breast Cancer

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

Qiao, L; Deng, G; Xie, J

2015-06-15

Purpose: To compare the dosimetric characteristics of volumetric-modulated arc therapy (VMAT) and intensity-modulated radiotherapy (IMRT) techniques in treatment planning for left-sided breast cancer patients with modified radical mastectomy. Methods: Twenty-four left-sided breast cancer patients treated with modified radical mastectomy were selected in this study. The planning target volume (PTV) was generated by using 7-mm uniform expansion of the clinical target volume (CTV) in all direction except the skin surface. The organs at risk (OARs) included heart, left lung, right lung, and right breast. Dose volume histograms (DVHs) were utilized to evaluate the dose distribution in PTV and OARs. Results: Bothmore » VMAT and IMRT plans met the requirement of PTV coverage. VMAT was superior to IMRT in terms of conformity, with a statistically significant difference (p=0.024). Mean doses, V5 and V10 of heart and both lungs in VMAT plans were significantly decreased compared to IMRT plans (P<0.05), but in terms of heart volume irradiated by high doses (V30 and V45), no significant differences were observed (P>0.05). For right breast, VMAT showed the reduction of V5 in comparison with IMRT (P<0.05). Additionally, the mean number of monitor units (MU) and treatment time in VMAT (357.21, 3.62 min) were significantly less than those in IMRT (1132.85, 8.74 min). Conclusion: VMAT showed similar PTV coverage and significant advantage in OARs sparing compared with IMRT, especially in terms of decreased volumes irradiated by low doses, while significantly reducing the treatment time and MU number.« less

Redesigning Radiotherapy Quality Assurance: Opportunities to Develop an Efficient, Evidence-Based System to Support Clinical Trials-Report of the National Cancer Institute Work Group on Radiotherapy Quality Assurance

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

Bekelman, Justin E., E-mail: bekelman@uphs.upenn.edu; Deye, James A.; Vikram, Bhadrasain

2012-07-01

Purpose: In the context of national calls for reorganizing cancer clinical trials, the National Cancer Institute sponsored a 2-day workshop to examine challenges and opportunities for optimizing radiotherapy quality assurance (QA) in clinical trial design. Methods and Materials: Participants reviewed the current processes of clinical trial QA and noted the QA challenges presented by advanced technologies. The lessons learned from the radiotherapy QA programs of recent trials were discussed in detail. Four potential opportunities for optimizing radiotherapy QA were explored, including the use of normal tissue toxicity and tumor control metrics, biomarkers of radiation toxicity, new radiotherapy modalities such asmore » proton beam therapy, and the international harmonization of clinical trial QA. Results: Four recommendations were made: (1) to develop a tiered (and more efficient) system for radiotherapy QA and tailor the intensity of QA to the clinical trial objectives (tiers include general credentialing, trial-specific credentialing, and individual case review); (2) to establish a case QA repository; (3) to develop an evidence base for clinical trial QA and introduce innovative prospective trial designs to evaluate radiotherapy QA in clinical trials; and (4) to explore the feasibility of consolidating clinical trial QA in the United States. Conclusion: Radiotherapy QA can affect clinical trial accrual, cost, outcomes, and generalizability. To achieve maximum benefit, QA programs must become more efficient and evidence-based.« less

Redesigning radiotherapy quality assurance: opportunities to develop an efficient, evidence-based system to support clinical trials--report of the National Cancer Institute Work Group on Radiotherapy Quality Assurance.

PubMed

Bekelman, Justin E; Deye, James A; Vikram, Bhadrasain; Bentzen, Soren M; Bruner, Deborah; Curran, Walter J; Dignam, James; Efstathiou, Jason A; FitzGerald, T J; Hurkmans, Coen; Ibbott, Geoffrey S; Lee, J Jack; Merchant, Thomas E; Michalski, Jeff; Palta, Jatinder R; Simon, Richard; Ten Haken, Randal K; Timmerman, Robert; Tunis, Sean; Coleman, C Norman; Purdy, James

2012-07-01

In the context of national calls for reorganizing cancer clinical trials, the National Cancer Institute sponsored a 2-day workshop to examine challenges and opportunities for optimizing radiotherapy quality assurance (QA) in clinical trial design. Participants reviewed the current processes of clinical trial QA and noted the QA challenges presented by advanced technologies. The lessons learned from the radiotherapy QA programs of recent trials were discussed in detail. Four potential opportunities for optimizing radiotherapy QA were explored, including the use of normal tissue toxicity and tumor control metrics, biomarkers of radiation toxicity, new radiotherapy modalities such as proton beam therapy, and the international harmonization of clinical trial QA. Four recommendations were made: (1) to develop a tiered (and more efficient) system for radiotherapy QA and tailor the intensity of QA to the clinical trial objectives (tiers include general credentialing, trial-specific credentialing, and individual case review); (2) to establish a case QA repository; (3) to develop an evidence base for clinical trial QA and introduce innovative prospective trial designs to evaluate radiotherapy QA in clinical trials; and (4) to explore the feasibility of consolidating clinical trial QA in the United States. Radiotherapy QA can affect clinical trial accrual, cost, outcomes, and generalizability. To achieve maximum benefit, QA programs must become more efficient and evidence-based. Copyright © 2012 Elsevier Inc. All rights reserved.

Study of Variation in Dose Calculation Accuracy Between kV Cone-Beam Computed Tomography and kV fan-Beam Computed Tomography

PubMed Central

Kaliyaperumal, Venkatesan; Raphael, C. Jomon; Varghese, K. Mathew; Gopu, Paul; Sivakumar, S.; Boban, Minu; Raj, N. Arunai Nambi; Senthilnathan, K.; Babu, P. Ramesh

2017-01-01

Cone-beam computed tomography (CBCT) images are presently used for geometric verification for daily patient positioning. In this work, we have compared the images of CBCT with the images of conventional fan beam CT (FBCT) in terms of image quality and Hounsfield units (HUs). We also compared the dose calculated using CBCT with that of FBCT. Homogenous RW3 plates and Catphan phantom were scanned by FBCT and CBCT. In RW3 and Catphan phantom, percentage depth dose (PDD), profiles, isodose distributions (for intensity modulated radiotherapy plans), and calculated dose volume histograms were compared. The HU difference was within ± 20 HU (central region) and ± 30 HU (peripheral region) for homogeneous RW3 plates. In the Catphan phantom, the difference in HU was ± 20 HU in the central area and peripheral areas. The HU differences were within ± 30 HU for all HU ranges starting from −1000 to 990 in phantom and patient images. In treatment plans done with simple symmetric and asymmetric fields, dose difference (DD) between CBCT plan and FBCT plan was within 1.2% for both phantoms. In intensity modulated radiotherapy (IMRT) treatment plans, for different target volumes, the difference was <2%. This feasibility study investigated HU variation and dose calculation accuracy between FBCT and CBCT based planning and has validated inverse planning algorithms with CBCT. In our study, we observed a larger deviation of HU values in the peripheral region compared to the central region. This is due to the ring artifact and scatter contribution which may prevent the use of CBCT as the primary imaging modality for radiotherapy treatment planning. The reconstruction algorithm needs to be modified further for improving the image quality and accuracy in HU values. However, our study with TG-119 and intensity modulated radiotherapy test targets shows that CBCT can be used for adaptive replanning as the recalculation of dose with the anisotropic analytical algorithm is in full accord with conventional planning CT except in the build-up regions. Patient images with CBCT have to be carefully analyzed for any artifacts before using them for such dose calculations. PMID:28974864

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

Kole, Thomas P.; Aghayere, Osarhieme; Kwah, Jason

Purpose: To compare heart and coronary artery radiation exposure using intensity-modulated radiotherapy (IMRT) vs. four-field three-dimensional conformal radiotherapy (3D-CRT) treatment plans for patients with distal esophageal cancer undergoing chemoradiation. Methods and Materials: Nineteen patients with distal esophageal cancers treated with IMRT from March 2007 to May 2008 were identified. All patients were treated to 50.4 Gy with five-field IMRT plans. Theoretical 3D-CRT plans with four-field beam arrangements were generated. Dose-volume histograms of the planning target volume, heart, right coronary artery, left coronary artery, and other critical normal tissues were compared between the IMRT and 3D-CRT plans, and selected parameters weremore » statistically evaluated using the Wilcoxon rank-sum test. Results: Intensity-modulated radiotherapy treatment planning showed significant reduction (p < 0.05) in heart dose over 3D-CRT as assessed by average mean dose (22.9 vs. 28.2 Gy) and V30 (24.8% vs. 61.0%). There was also significant sparing of the right coronary artery (average mean dose, 23.8 Gy vs. 35.5 Gy), whereas the left coronary artery showed no significant improvement (mean dose, 11.2 Gy vs. 9.2 Gy), p = 0.11. There was no significant difference in percentage of total lung volume receiving at least 10, 15, or 20 Gy or in the mean lung dose between the planning methods. There were also no significant differences observed for the kidneys, liver, stomach, or spinal cord. Intensity-modulated radiotherapy achieved a significant improvement in target conformity as measured by the conformality index (ratio of total volume receiving 95% of prescription dose to planning target volume receiving 95% of prescription dose), with the mean conformality index reduced from 1.56 to 1.30 using IMRT. Conclusions: Treatment of patients with distal esophageal cancer using IMRT significantly decreases the exposure of the heart and right coronary artery when compared with 3D-CRT. Long-term studies are necessary to determine how this will impact on development of coronary artery disease and other cardiac complications.« less

Changes in salivary gland function after radiotherapy of head and neck tumors measured by quantitative pertechnetate scintigraphy: Comparison of intensity-modulated radiotherapy and conventional radiation therapy with and without Amifostine

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

Muenter, Marc W.; Hoffner, Simone; Department of Nuclear Medicine, University of Heidelberg, Heidelberg

2007-03-01

Purpose: The aim of this study was to compare changes in salivary gland function after intensity-modulated radiotherapy (IMRT) and conventional radiotherapy (RT), with or without Amifostine, for tumors of the head-and-neck region using quantitative salivary gland scintigraphy (QSGS). Methods and Materials: A total of 75 patients received pre- and post-therapeutic QSGS to quantify the salivary gland function. In all, 251 salivary glands were independently evaluated. Changes in the maximum uptake ({delta}U) and relative excretion rate ({delta}F) both pre- and post-RT were determined to characterize radiation-induced changes in the salivary gland function. In addition, dose-response curves were calculated. Results: In allmore » groups, maximum uptake and relative excretion rate were reduced after RT ({delta}U {<=}0 and {delta}F {<=}0). The reduction was significantly lower for IMRT than for conventional RT. For the parotid glands, the reduction was smaller for the IMRT-low than for the IMRT-high group. For the Amifostine-high and the conventional group the difference was significant only for one parameter ({delta}U, parotid and submandibular glands, p < 0.05). In contrast to this, the difference between the Amifostine-low and the conventional group was always significant or at least showed a clear trend for both changes in U and F. In regard to the endpoint 'reduction of the salivary gland excretion rate of more than 50%,' the dose-response curves yielded D{sub 50}-values of 34.2 {+-} 12.2 Gy for the conventionally treated group and 36.8 {+-} 2.9 Gy for the IMRT group. For the Amifostine group, an increased D{sub 50}-values of 46.3 {+-} 2.3 Gy was obtained. Conclusion: Intensity-modulated RT can significantly reduce the loss of parotid gland function when respecting a certain dose threshold. Conventional RT plus Amifostine prevents reduced salivary gland function only in the patient group treated with <40.6 Gy.« less

Reduced toxicity with three-dimensional conformal radiotherapy or intensity-modulated radiotherapy compared with conventional two-dimensional radiotherapy for esophageal squamous cell carcinoma: a secondary analysis of data from four prospective clinical trials.

PubMed

Deng, J-Y; Wang, C; Shi, X-H; Jiang, G-L; Wang, Y; Liu, Y; Zhao, K-L

2016-11-01

We conducted a retrospective analysis to assess the toxicity and long-term survival of esophageal squamous cell carcinoma patients treated with three-dimensional conformal radiotherapy (3DCRT) or intensity-modulated radiotherapy (IMRT) versus conventional two-dimensional radiotherapy (2DRT). All data in the present study were based on four prospective clinical trials conducted at our institution from 1996 to 2004 and included 308 esophageal squamous cell carcinoma patients treated with 2DRT or 3DCRT/IMRT. Based on the inclusion and exclusion criteria, 254 patients were included in the analysis. Of these patients, 158 were treated with 2DRT, whereas 96 were treated with 3DCRT/IMRT. The rates of ≥Grade3 acute toxicity of the esophagus and lung were 11.5% versus 28.5% (P = 0.002) and 5.2% versus 10.8% (P = 0.127) in the 3DCRT/IMRT and 2DRT groups, respectively. The incidences of ≥Grade 3 late toxicity of the esophagus and lungs were 3.1% versus 10.7% (P = 0.028) and 3.1% versus 5.7% (P = 0.127) in the 3DCRT/IMRT and 2DRT groups, respectively. The 1-year, 3-year and 5-year estimated overall survival rates were 81%, 38% and 34% in the 3DCRT/IMRT group and 79%, 44% and 31% in the 2DRT group, respectively (P = 0.628). The 1-year, 3-year and 5-year local control rates were 88%, 71% and 66% in the 3DCRT/IMRT group and 84%, 66% and 60% in the 2DRT group, respectively (P = 0.412). Fewer incidences of acute and late toxicities were observed in esophageal squamous cell carcinoma patients treated with 3DCRT/IMRT compared with those treated with 2DRT. No significant survival benefit was observed with the use of 3DCRT/IMRT. © 2015 International Society for Diseases of the Esophagus.

Tumor volume changes on serial imaging with megavoltage CT for non-small-cell lung cancer during intensity-modulated radiotherapy: how reliable, consistent, and meaningful is the effect?

PubMed

Siker, Malika L; Tomé, Wolfgang A; Mehta, Minesh P

2006-09-01

Adaptive radiotherapy allows treatment plan modification based on data obtained during treatment. Assessing volume changes during treatment is now possible with intratreatment imaging capabilities on radiotherapy devices. This study assesses non-small-cell lung cancer (NSCLC) volume changes during treatment with conformal intensity-modulated radiotherapy by evaluating serial megavoltage computed tomography (MVCT) scans, with a specific emphasis on the frequency, reliability, and meaningfulness of these changes. Megavoltage CTs were retrospectively reviewed for 25 patients treated with the TomoTherapy Hi-Art system at the University of Wisconsin. Twenty-one patients received definitive radiotherapy, 4 with extracranial stereotactic radioablation (60 Gy in five fractions) and 17 on a dose-per-fraction escalation protocol (57-80.5 Gy in 25 fractions). Four patients were treated palliatively (22-30 Gy in 8 to 10 fractions). Gross tumor volumes were contoured on serial MVCTs at weekly intervals. Each patient had 4 to 25 scans, including at least one at the beginning, midway, and one at the end of treatment. At completion of treatment, no patient demonstrated a complete response. Partial response occurred in 3 (12%) and marginal response was noted in 5 (20%). The remaining 17 patients (68%) showed stable disease. The minimum "scorable threshold" for volume discrepancy between scans to account for interscan assessment variability was set at >25% volume change; 10 patients (40%) had >25% tumor regression. None of the patients treated ablatively or palliatively showed tumor regression during treatment. Although gross tumor regression during treatment may be objectively measured using MVCTs, substantial volumetric decrease occurs only in a minority. The clinical significance of this regression is questionable, because there is no way to document histologic tumor clearance, and therefore field reductions during radiotherapy cannot be recommended.

An Automated Treatment Plan Quality Control Tool for Intensity-Modulated Radiation Therapy Using a Voxel-Weighting Factor-Based Re-Optimization Algorithm

PubMed Central

Song, Ting; Li, Nan; Zarepisheh, Masoud; Li, Yongbao; Gautier, Quentin; Zhou, Linghong; Mell, Loren; Jiang, Steve; Cerviño, Laura

2016-01-01

Intensity-modulated radiation therapy (IMRT) currently plays an important role in radiotherapy, but its treatment plan quality can vary significantly among institutions and planners. Treatment plan quality control (QC) is a necessary component for individual clinics to ensure that patients receive treatments with high therapeutic gain ratios. The voxel-weighting factor-based plan re-optimization mechanism has been proved able to explore a larger Pareto surface (solution domain) and therefore increase the possibility of finding an optimal treatment plan. In this study, we incorporated additional modules into an in-house developed voxel weighting factor-based re-optimization algorithm, which was enhanced as a highly automated and accurate IMRT plan QC tool (TPS-QC tool). After importing an under-assessment plan, the TPS-QC tool was able to generate a QC report within 2 minutes. This QC report contains the plan quality determination as well as information supporting the determination. Finally, the IMRT plan quality can be controlled by approving quality-passed plans and replacing quality-failed plans using the TPS-QC tool. The feasibility and accuracy of the proposed TPS-QC tool were evaluated using 25 clinically approved cervical cancer patient IMRT plans and 5 manually created poor-quality IMRT plans. The results showed high consistency between the QC report quality determinations and the actual plan quality. In the 25 clinically approved cases that the TPS-QC tool identified as passed, a greater difference could be observed for dosimetric endpoints for organs at risk (OAR) than for planning target volume (PTV), implying that better dose sparing could be achieved in OAR than in PTV. In addition, the dose-volume histogram (DVH) curves of the TPS-QC tool re-optimized plans satisfied the dosimetric criteria more frequently than did the under-assessment plans. In addition, the criteria for unsatisfied dosimetric endpoints in the 5 poor-quality plans could typically be satisfied when the TPS-QC tool generated re-optimized plans without sacrificing other dosimetric endpoints. In addition to its feasibility and accuracy, the proposed TPS-QC tool is also user-friendly and easy to operate, both of which are necessary characteristics for clinical use. PMID:26930204

[Doses to organs at risk in conformational radiotherapy and stereotaxic irradiation: The heart].

PubMed

Vandendorpe, B; Servagi Vernat, S; Ramiandrisoa, F; Bazire, L; Kirova, Y M

2017-10-01

Radiation therapy of breast cancer, Hodgkin lymphoma, lung cancer and others thoracic irradiations induce an ionizing radiation dose to the heart. Irradiation of the heart, associated with patient cardiovascular risk and cancer treatment-induced cardiotoxicity, increase cardiovascular mortality. The long survival after breast or Hodgkin lymphoma irradiation requires watching carefully late treatment toxicity. The over-risk of cardiac events is related to the dose received by the heart and the irradiated cardiac volume. The limitation of cardiac irradiation should be a priority in the planning of thoracic irradiations. Practices have to be modified, using modern techniques to approach of the primary objective of radiotherapy which is to optimize the dose to the target volume, sparing healthy tissues, in this case the heart. We have reviewed the literature on cardiac toxicity induced by conformational tridimensional radiation therapy, intensity-modulated radiation therapy or stereotactic body radiation therapy, in order to evaluate the possibilities to limit cardiotoxicity. Finally, we summarise the recommendations on dose constraints to the heart and coronary arteries. Copyright © 2017 Société française de radiothérapie oncologique (SFRO). Published by Elsevier SAS. All rights reserved.

The use of hypofractionated intensity-modulated irradiation in the treatment of glioblastoma multiforme: preliminary results of a prospective trial.

PubMed

Sultanem, Khalil; Patrocinio, Horacio; Lambert, Christine; Corns, Robert; Leblanc, Richard; Parker, William; Shenouda, George; Souhami, Luis

2004-01-01

Despite major advances in treatment modalities, the prognosis of patients with glioblastoma multiforme (GBM) remains poor. Exploring hypofractionated regimens to replace the standard 6-week radiotherapy schedule is an attractive strategy as an attempt to prevent accelerated tumor cell repopulation. There is equally interest in dose escalation to the gross tumor volume where the majority of failures occur. We report our preliminary results using hypofractionated intensity-modulated accelerated radiotherapy regimen in the treatment of patients with GBM. Between July 1998 and December 2001, 25 patients with histologically proven diagnosis of GBM, Karnofsky performance status > or =60, and a postoperative tumor volume < or =110 cm3 were treated with a hypofractionated accelerated course of radiotherapy. The gross tumor volume (GTV) was defined as the contrast-enhancing lesion on the postoperative MRI T1-weighted images with the latter fused with computed tomography images for treatment planning. The planning target volume was defined as GTV + 1.5-cm margin. Using forward-planning intensity modulation (step-and-shoot technique), 60 Gy in 20 daily fractions of 3 Gy each were given to the GTV, whereas the planning target volume received a minimum of 40 Gy in 20 fractions of 2 Gy each at its periphery. Treatments were delivered over a 4-week period using 5 daily fractions per week. Dose was prescribed at the isocenter (ICRU point). Three beam angles were used in all of the cases. Treatments were well tolerated. Acute toxicity was limited to increased brain edema during radiotherapy in 2 patients who were on tapering doses of corticosteroids. This was corrected by increasing the steroid dose. At a median follow-up of 8.8 months, no late toxicity was observed. One patient experienced visual loss at 9 months after completion of treatment. MRI suggested nonspecific changes to the optic chiasm. On review of the treatment plan, the total dose to the optic chiasm was confirmed to be equal to or less than 40 Gy in 20 fractions. When Radiation Therapy Oncology Group recursive partitioning analysis was used, 10 patients were class III-IV, and 15 patients were class V-VI. To date, 21 patients have had clinical and/or radiologic evidence of disease progression, and 16 patients have died. The median survival was 9.5 months (range: 2.8-22.9 months), the 1-year survival rate was 40%, and the median progression-free survival was 5.2 months (range: 1.9-12.8 months). This hypofractionated accelerated irradiation schedule using forward planning (step-and-shoot) hypofractionated, intensity-modulated accelerated radiotherapy is feasible and seems to be a safe treatment for patients with GBM. A 2-week reduction in the treatment time may be of valuable benefit for this group of patients. However, despite this accelerated regimen, no survival advantage has been observed.

Dosimetry for audit and clinical trials: challenges and requirements

NASA Astrophysics Data System (ADS)

Kron, T.; Haworth, A.; Williams, I.

2013-06-01

Many important dosimetry audit networks for radiotherapy have their roots in clinical trial quality assurance (QA). In both scenarios it is essential to test two issues: does the treatment plan conform with the clinical requirements and is the plan a reasonable representation of what is actually delivered to a patient throughout their course of treatment. Part of a sound quality program would be an external audit of these issues with verification of the equivalence of plan and treatment typically referred to as a dosimetry audit. The increasing complexity of radiotherapy planning and delivery makes audits challenging. While verification of absolute dose delivered at a reference point was the standard of external dosimetry audits two decades ago this is often deemed inadequate for verification of treatment approaches such as Intensity Modulated Radiation Therapy (IMRT) and Volumetric Modulated Arc Therapy (VMAT). As such, most dosimetry audit networks have successfully introduced more complex tests of dose delivery using anthropomorphic phantoms that can be imaged, planned and treated as a patient would. The new challenge is to adapt this approach to ever more diversified radiotherapy procedures with image guided/adaptive radiotherapy, motion management and brachytherapy being the focus of current research.

The Comparison Study of Quadratic Infinite Beam Program on Optimization Instensity Modulated Radiation Therapy Treatment Planning (IMRTP) between Threshold and Exponential Scatter Method with CERR® In The Case of Lung Cancer

NASA Astrophysics Data System (ADS)

Hardiyanti, Y.; Haekal, M.; Waris, A.; Haryanto, F.

2016-08-01

This research compares the quadratic optimization program on Intensity Modulated Radiation Therapy Treatment Planning (IMRTP) with the Computational Environment for Radiotherapy Research (CERR) software. We assumed that the number of beams used for the treatment planner was about 9 and 13 beams. The case used the energy of 6 MV with Source Skin Distance (SSD) of 100 cm from target volume. Dose calculation used Quadratic Infinite beam (QIB) from CERR. CERR was used in the comparison study between Gauss Primary threshold method and Gauss Primary exponential method. In the case of lung cancer, the threshold variation of 0.01, and 0.004 was used. The output of the dose was distributed using an analysis in the form of DVH from CERR. The maximum dose distributions obtained were on the target volume (PTV) Planning Target Volume, (CTV) Clinical Target Volume, (GTV) Gross Tumor Volume, liver, and skin. It was obtained that if the dose calculation method used exponential and the number of beam 9. When the dose calculation method used the threshold and the number of beam 13, the maximum dose distributions obtained were on the target volume PTV, GTV, heart, and skin.

Development and evaluation of multi-energy PbO dosimeter for quality assurance of image-guide radiation therapy devices

NASA Astrophysics Data System (ADS)

Kim, Kyo-Tae; Heo, Ye-Ji; Han, Moo-Jae; Oh, Kyung-Min; Lee, Young-Kyu; Kim, Shin-Wook; Park, Sung-Kwang

2017-04-01

In radiation therapy, accurate radiotherapy treatment plan (RTP) reproduction is necessary to optimize the clinical results. Thus, attempts have recently been made to ensure high RTP reproducibility using image-guide radiation therapy (IGRT) technology. However, the clinical use of digital X-ray equipment requires extended quality assurance (QA) for those devices, since the IGRT device quality determines the precision of intensity-modulated radiation therapy. The study described in this paper was focused on developing a multi-energy PbO dosimeter for IGRT device QA. The Schottky-type polycrystalline PbO dosimeter with a Au/PbO/ITO structure was evaluated by comparing its response coincidence, dose linearity, measurement reproducibility, linear attenuation coefficient, and percent depth dose with those of Si diode and standard ionization chamber dosimeters.

FoCa: a modular treatment planning system for proton radiotherapy with research and educational purposes

NASA Astrophysics Data System (ADS)

Sánchez-Parcerisa, D.; Kondrla, M.; Shaindlin, A.; Carabe, A.

2014-12-01

FoCa is an in-house modular treatment planning system, developed entirely in MATLAB, which includes forward dose calculation of proton radiotherapy plans in both active and passive modalities as well as a generic optimization suite for inverse treatment planning. The software has a dual education and research purpose. From the educational point of view, it can be an invaluable teaching tool for educating medical physicists, showing the insights of a treatment planning system from a well-known and widely accessible software platform. From the research point of view, its current and potential uses range from the fast calculation of any physical, radiobiological or clinical quantity in a patient CT geometry, to the development of new treatment modalities not yet available in commercial treatment planning systems. The physical models in FoCa were compared with the commissioning data from our institution and show an excellent agreement in depth dose distributions and longitudinal and transversal fluence profiles for both passive scattering and active scanning modalities. 3D dose distributions in phantom and patient geometries were compared with a commercial treatment planning system, yielding a gamma-index pass rate of above 94% (using FoCa’s most accurate algorithm) for all cases considered. Finally, the inverse treatment planning suite was used to produce the first prototype of intensity-modulated, passive-scattered proton therapy, using 13 passive scattering proton fields and multi-leaf modulation to produce a concave dose distribution on a cylindrical solid water phantom without any field-specific compensator.

New technologies in radiation therapy: ensuring patient safety, radiation safety and regulatory issues in radiation oncology.

PubMed

Amols, Howard I

2008-11-01

New technologies such as intensity modulated and image guided radiation therapy, computer controlled linear accelerators, record and verify systems, electronic charts, and digital imaging have revolutionized radiation therapy over the past 10-15 y. Quality assurance (QA) as historically practiced and as recommended in reports such as American Association of Physicists in Medicine Task Groups 40 and 53 needs to be updated to address the increasing complexity and computerization of radiotherapy equipment, and the increased quantity of data defining a treatment plan and treatment delivery. While new technology has reduced the probability of many types of medical events, seeing new types of errors caused by improper use of new technology, communication failures between computers, corrupted or erroneous computer data files, and "software bugs" are now being seen. The increased use of computed tomography, magnetic resonance, and positron emission tomography imaging has become routine for many types of radiotherapy treatment planning, and QA for imaging modalities is beyond the expertise of most radiotherapy physicists. Errors in radiotherapy rarely result solely from hardware failures. More commonly they are a combination of computer and human errors. The increased use of radiosurgery, hypofractionation, more complex intensity modulated treatment plans, image guided radiation therapy, and increasing financial pressures to treat more patients in less time will continue to fuel this reliance on high technology and complex computer software. Clinical practitioners and regulatory agencies are beginning to realize that QA for new technologies is a major challenge and poses dangers different in nature than what are historically familiar.

Intensity modulated radiotherapy with simultaneous integrated boost vs. conventional radiotherapy with sequential boost for breast cancer - A preliminary result.

PubMed

Lee, Hsin-Hua; Hou, Ming-Feng; Chuang, Hung-Yi; Huang, Ming-Yii; Tsuei, Le-Ping; Chen, Fang-Ming; Ou-Yang, Fu; Huang, Chih-Jen

2015-10-01

This study was aimed to assess the acute dermatological adverse effect from two distinct RT techniques for breast cancer patients. We compared intensity-modulated radiotherapy with simultaneous integrated boost (IMRT-SIB) and conventional radiotherapy followed by sequential boost (CRT-SB). The study population was composed of 126 consecutive female breast cancer patients treated with breast conserving surgery. Sixty-six patients received IMRT-SIB to 2 dose levels simultaneously. They received 50.4 Gy at 1.8 Gy per fraction to the whole breast and 60.2 Gy at 2.15 Gy per fraction to the tumor bed by integral boost. Sixty patients in the CRT-SB group received 50 Gy in 25 fractions to the whole breast followed by a boost irradiation to tumor bed in 5-7 fractions to a total dose of 60-64 Gy. Acute skin toxicities were documented in agreement with the Common Terminology Criteria for Adverse Events version 3 (CTCAE v.3.0). Ninety-eight patients had grade 1 radiation dermatitis while 14 patients had grade 2. Among those with grade 2, there were 3 patients in IMRT-SIB group (4.5%) while 11 in CRT-SB group (18.3%). (P = 0.048) There was no patient with higher than grade 2 toxicity. Three year local control was 99.2%, 3-year disease free survival was 97.5% and 3-year overall survival was 99.2%. A significant reduction in the severity of acute radiation dermatitis from IMRT-SIB comparing with CRT-SB is demonstrated. Copyright © 2015 Elsevier Ltd. All rights reserved.

Xerostomia, salivary characteristics and gland volumes following intensity-modulated radiotherapy for nasopharyngeal carcinoma: a two-year follow up.

PubMed

Sim, Cpc; Soong, Y L; Pang, Epp; Lim, C; Walker, G D; Manton, D J; Reynolds, E C; Wee, Jts

2018-06-01

To evaluate changes in xerostomia status, salivary characteristics and gland volumes 2 years following radiotherapy in nasopharyngeal carcinoma patients. Xerostomia scores, salivary flow rates, pH and buffering capacity were measured at pre-radiotherapy, mid-radiotherapy, 2 weeks, 3 months and 2 years post-radiotherapy. Salivary gland volumes and their correlation with radiation dose were also assessed. Mean radiation dose to oral cavity, parotid and submandibular glands (SMG) was 44.5, 65.0 and 38.6 Gy respectively. Parotid and SMG volumes decreased 33% at 3 months post-radiotherapy; volumes at 2 years post-radiotherapy were 84% and 51% of pre-radiotherapy levels, respectively. Correlations were observed between parotid gland volume per cent reduction and its radiation dose and between resting salivary flow rate reduction and post-radiotherapy/pre-radiotherapy SMG volume ratio. Salivary flow rates and resting saliva pH remained significantly low at 2 years post-radiotherapy (both flow rates, P = 0.001; resting saliva pH, P = 0.005). Similarly, xerostomia scores remained significantly higher compared with pre-radiotherapy levels. Submandibular gland volumetric shrinkage persisted 2 years after radiotherapy. Xerostomia scores remained significantly higher, and salivary flow rates and resting saliva pH remained significantly lower, suggesting that study participants were still at risk for hyposalivation-related oral diseases. © 2018 Australian Dental Association.

Comparison of intensity-modulated radiotherapy and volumetric-modulated arc therapy dose measurement for head and neck cancer using optical stimulated luminescence dosimeter

NASA Astrophysics Data System (ADS)

Lai, Lu-Han; Chuang, Keh-Shih; Lin, Hsin-Hon; Liu, Yi-Chi; Kuo, Chiung-Wen; Lin, Jao-Perng

2017-11-01

The in-vivo dose distributions of intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT), a newly developed technique, for head and neck cancer have been investigated for several years. The present study used a head-and-neck RANDO phantom to simulate the clinical conditions of nasopharyngeal carcinoma and compare the radiation doses between VMAT and IMRT. Three types of planning target volume (PTV) profiles were targeted by reducing the PTV surface margin by 0, 3, and 5 mm. An optically stimulated luminescence dosimeter was used to measure the surface doses. The results revealed that VMAT provided on average 16.8-13.8% lower surface doses within the PTV target areas than IMRT. When the PTV margin was reduced by 0 mm, the surface doses for IMRT reached their maximum value, accounting for 75.1% of its prescribed dose (Dp); however, the Dp value of VMAT was only 61.1%. When the PTV margin was reduced by 3 or 5 mm, the surface doses decreased considerably. The observed surface doses were insufficient when the tumours invaded the body surface; however, VMAT exerted larger skin-sparing effects than IMRT when the tumours away from the skin. These results suggest that the skin doses for these two techniques are insufficient for surface tumours. Notably, VMAT can provide lower skin doses for deep tumours.

Long-term decision regret after post-prostatectomy image-guided intensity-modulated radiotherapy.

PubMed

Shakespeare, Thomas P; Chin, Stephen; Manuel, Lucy; Wen, Shelly; Hoffman, Matthew; Wilcox, Shea W; Aherne, Noel J

2017-02-01

Decision regret (DR) may occur when a patient believes their outcome would have been better if they had decided differently about their management. Although some studies investigate DR after treatment for localised prostate cancer, none report DR in patients undergoing surgery and post-prostatectomy radiotherapy. We evaluated DR in this group of patients overall, and for specific components of therapy. We surveyed 83 patients, with minimum 5 years follow-up, treated with radical prostatectomy (RP) and post-prostatectomy image-guided intensity-modulated radiotherapy (IG-IMRT) to 64-66 Gy following www.EviQ.org.au protocols. A validated questionnaire identified DR if men either indicated that they would have been better off had they chosen another treatment, or they wished they could change their mind about treatment. There was an 85.5% response rate, with median follow-up post-IMRT 78 months. Adjuvant IG-IMRT was used in 28% of patients, salvage in 72% and ADT in 48%. A total of 70% of patients remained disease-free. Overall, 16.9% of patients expressed DR for treatment, with fourfold more regret for the RP component of treatment compared to radiotherapy (16.9% vs 4.2%, P = 0.01). DR for androgen deprivation was 14.3%. Patients were regretful of surgery due to toxicity, not being adequately informed about radiotherapy as an alternative, positive margins and surgery costs (83%, 33%, 25% and 8% of regretful patients respectively). Toxicity caused DR in the three radiotherapy-regretful and four ADT-regretful patients. Patients were twice as regretful overall, and of surgery, for salvage vs adjuvant approaches (both 19.6% vs 10.0%). Decision regret after RP and post-prostatectomy IG-IMRT is uncommon, although patients regret RP more than post-operative IG-IMRT. This should reassure urologists referring patients for post-prostatectomy IG-IMRT, particularly in the immediate adjuvant setting. Other implications include appropriate patient selection for RP (and obtaining clear margins), and ensuring adequately discussing definitive radiotherapy as an alternative to surgery. © 2016 The Royal Australian and New Zealand College of Radiologists.

Pretreatment risk stratification of feeding tube use in patients treated with intensity-modulated radiotherapy for head and neck cancer.

PubMed

Anderson, Nigel J; Jackson, James E; Smith, Jennifer G; Wada, Morikatsu; Schneider, Michal; Poulsen, Michael; Rolfo, Maureen; Fahandej, Maziar; Gan, Hui; Joon, Daryl Lim; Khoo, Vincent

2018-05-13

The purpose of this study was to establish a risk stratification model for feeding tube use in patients who undergo intensity-modulated radiotherapy (IMRT) for head and neck cancers. One hundred thirty-nine patients treated with definitive IMRT (+/- concurrent chemotherapy) for head and neck mucosal cancers were included in this study. Patients were recommended a prophylactic feeding tube and followed up by a dietician for at least 8 weeks postradiotherapy (post-RT). Potential prognostic factors were analyzed for risk and duration of feeding tube use for at least 25% of dietary requirements. Many variables had significant effects on risk and/or duration of feeding tube use in univariate analyses. Subsequent multivariable analysis showed that T classification ≥3 and level 2 lymphadenopathy were the best independent significant predictors of higher risk and duration of feeding tube use, respectively, in oral cavity, pharyngeal, and supraglottic primaries. In patients treated with definitive IMRT, T classification ≥3 and level 2 lymphadenopathy can potentially stratify patients into 4 risk groups for developing severe dysphagia requiring feeding tube use. © 2018 Wiley Periodicals, Inc.

Impact of xerostomia on dysphagia after chemotherapy-intensity-modulated radiotherapy for oropharyngeal cancer: Prospective longitudinal study.

PubMed

Vainshtein, Jeffrey M; Samuels, Stuart; Tao, Yebin; Lyden, Teresa; Haxer, Marc; Spector, Matthew; Schipper, Matthew; Eisbruch, Avraham

2016-04-01

The purpose of this study was to assess how xerostomia affects dysphagia. Prospective longitudinal studies of 93 patients with oropharyngeal cancer treated with definitive chemotherapy-intensity-modulated radiotherapy (IMRT). Observer-rated dysphagia (ORD), patient-reported dysphagia (PRD), and patient-reported xerostomia (PRX) assessment of the swallowing mechanics by videofluoroscopy (videofluoroscopy score), and salivary flow rates, were prospectively assessed from pretherapy through 2 years. ORD grades ≥2 were rare and therefore not modeled. Of patients with no/mild videofluoroscopy abnormalities, a substantial proportion had PRD that peaked 3 months posttherapy and subsequently improved. Through 2 years, highly significant correlations were observed between PRX and PRD scores for all patients, including those with no/mild videofluoroscopy abnormalities. Both PRX and videofluoroscopy scores were highly significantly associated with PRD. On multivariate analysis, PRX score was a stronger predictor of PRD than the videofluoroscopy score. Xerostomia contributes significantly to PRD. Efforts to further decrease xerostomia, in addition to sparing parotid glands, may translate into improvements in PRD. © 2015 Wiley Periodicals, Inc. Head Neck 38: E1605-E1612, 2016. © 2015 Wiley Periodicals, Inc.

Integrated beam orientation and scanning-spot optimization in intensity-modulated proton therapy for brain and unilateral head and neck tumors.

PubMed

Gu, Wenbo; O'Connor, Daniel; Nguyen, Dan; Yu, Victoria Y; Ruan, Dan; Dong, Lei; Sheng, Ke

2018-04-01

Intensity-Modulated Proton Therapy (IMPT) is the state-of-the-art method of delivering proton radiotherapy. Previous research has been mainly focused on optimization of scanning spots with manually selected beam angles. Due to the computational complexity, the potential benefit of simultaneously optimizing beam orientations and spot pattern could not be realized. In this study, we developed a novel integrated beam orientation optimization (BOO) and scanning-spot optimization algorithm for intensity-modulated proton therapy (IMPT). A brain chordoma and three unilateral head-and-neck patients with a maximal target size of 112.49 cm 3 were included in this study. A total number of 1162 noncoplanar candidate beams evenly distributed across 4π steradians were included in the optimization. For each candidate beam, the pencil-beam doses of all scanning spots covering the PTV and a margin were calculated. The beam angle selection and spot intensity optimization problem was formulated to include three terms: a dose fidelity term to penalize the deviation of PTV and OAR doses from ideal dose distribution; an L1-norm sparsity term to reduce the number of active spots and improve delivery efficiency; a group sparsity term to control the number of active beams between 2 and 4. For the group sparsity term, convex L2,1-norm and nonconvex L2,1/2-norm were tested. For the dose fidelity term, both quadratic function and linearized equivalent uniform dose (LEUD) cost function were implemented. The optimization problem was solved using the Fast Iterative Shrinkage-Thresholding Algorithm (FISTA). The IMPT BOO method was tested on three head-and-neck patients and one skull base chordoma patient. The results were compared with IMPT plans created using column generation selected beams or manually selected beams. The L2,1-norm plan selected spatially aggregated beams, indicating potential degeneracy using this norm. L2,1/2-norm was able to select spatially separated beams and achieve smaller deviation from the ideal dose. In the L2,1/2-norm plans, the [mean dose, maximum dose] of OAR were reduced by an average of [2.38%, 4.24%] and[2.32%, 3.76%] of the prescription dose for the quadratic and LEUD cost function, respectively, compared with the IMPT plan using manual beam selection while maintaining the same PTV coverage. The L2,1/2 group sparsity plans were dosimetrically superior to the column generation plans as well. Besides beam orientation selection, spot sparsification was observed. Generally, with the quadratic cost function, 30%~60% spots in the selected beams remained active. With the LEUD cost function, the percentages of active spots were in the range of 35%~85%.The BOO-IMPT run time was approximately 20 min. This work shows the first IMPT approach integrating noncoplanar BOO and scanning-spot optimization in a single mathematical framework. This method is computationally efficient, dosimetrically superior and produces delivery-friendly IMPT plans. © 2018 American Association of Physicists in Medicine.

Effects of intensity-modulated radiotherapy and chemoradiotherapy on attention in patients with nasopharyngeal cancer

PubMed Central

Wei, Qing; Li, Ling; Zhu, Xiao-Dong; Qin, Ling; Mo, Yan-Lin; Liang, Zheng-You; Deng, Jia-Li; Tao, Su-Ping

2017-01-01

This study evaluated the short-term effects of intensity-modulated radiotherapy (IMRT) and cisplatin concurrent chemo-radiotherapy (CCRT) on attention in patients with nasopharyngeal cancer (NPC). Timely detection and early prevention of cognitive decline are important in cancer patients, because long-term cognitive effects may be permanent and irreversible. Thirty-eight NPC patients treated with IMRT (17/38) or CCRT (21/38) and 38 healthy controls were recruited for the study. Neuropsychological tests were administered to each patient before treatment initiation and within a week after treatment completion. Changes in attention performance over time were evaluated using difference values (D-values). Decreased attention was already observable in patients with NPC prior to treatment. Baseline quotient scores for auditory attention, auditory and visual vigilance, and auditory speed were lower in patients treated with CCRT than in healthy controls (P=0.037, P=0.001, P=0.007, P=0.032, respectively). Auditory stamina D-values were higher in patients treated with IMRT alone (P=0.042), while full-scale response control quotient D-values were lower in patients treated with CCRT (P=0.030) than in healthy controls. Gender, depression, education, and sleep quality were each related to decreased attention and response control. Our results showed that IMRT had no negative acute effects on attention in NPC patients, while CCRT decreased response control. PMID:28947979

Radiotherapy after surgical resection for head and neck mucosal melanoma.

PubMed

Wu, Abraham J; Gomez, Jennifer; Zhung, Joanne E; Chan, Kelvin; Gomez, Daniel R; Wolden, Suzanne L; Zelefsky, Michael J; Wolchok, Jedd D; Carvajal, Richard D; Chapman, Paul B; Wong, Richard J; Shaha, Ashok R; Kraus, Dennis H; Shah, Jatin P; Lee, Nancy Y

2010-06-01

To present our single-institution experience with postoperative radiotherapy for mucosal melanoma of the head and neck. Between 1992 and 2007, 27 patients with mucosal melanoma of the head and neck underwent surgical resection followed by postoperative radiotherapy. Median age was 68 years (range: 45-89 years). Sites included were sinonasal in 24 patients, oral cavity in 2, and oropharynx in 1. All but 2 patients had stage I disease. Twenty-two patients received hypofractionated radiation. Radiation techniques were intensity-modulated radiation therapy in 13, 3-dimensional conformal in 4, and conventional in 10. The median follow-up for living patients was 45 months (range: 24-122 months). The 3- and 5-year estimates of local progression-free, loco-regional progression-free, distant metastasis-free, and overall survival were: 47% and 35%; 34% and 22%; 30% and 24%; and 40% and 33%, respectively. Median time to local failure and distant metastasis was 32 and 14 months, respectively. Acute toxicities included 19% with grade 2 or higher mucositis. No late complications related to the optic structures were seen. Modern radiotherapeutic techniques including intensity-modulated radiation therapy appear feasible and well-tolerated in the postoperative treatment of head and neck mucosal melanoma. Unusual or serious late complications have not been observed despite extensive use of hypofractionated regimens. However, rates of local and distant failure remain high.

[Intensity-modulated or 3-D conformal radiotherapy combined with chemotherapy with docetaxel and cisplatin for locally advanced esophageal carcinoma].

PubMed

Lin, Xiao-dan; Shi, Xing-yuan; Zhou, Tong-chong; Zhang, Wei-jun

2011-06-01

To evaluate the therapeutic effect and toxicity of intensity-modulated radiation therapy (IMRT) or three-dimensional conformal radiotherapy combined with chemotherapy (3-DCRT) with docetaxel and cisplatin in the treatment of locally advanced esophageal carcinoma. Sixty patients with locally advanced esophageal carcinoma were randomly assigned in two equal groups to receive IMRT or 3-DCRT, both combined with the chemotherapy with docetaxel and cisplatin. The total dose of radiotherapy was 64 Gy, administered in 30 fractions in 6 weeks. The complete response rate (complete and partial remissions) of IMRT group was 90.0%, significantly higher than the rate of 80.0% in 3-DCRT group (P>0.05). The 1-, 2-, and 3-year survival rates of IMRT group were 86.7%, 70.0%, and 66.7%, as compared to 70.0%, 63.3%, and 63.3% in 3-DCRT group, respectively, showing no significant differences between the two groups (P>0.05). IMRT showed advantages over 3-DCRT in terms of the V20 and V30 parameters of the lung (P<0.05), and the incidences of radiation-induced esophagitis were comparable between the two groups (P>0.05). When combined with the chemotherapy with docetaxel and cisplatin, IMRT appears to be a more effective treatment than 3-DCRT for locally advanced esophageal cancer.

Adjuvant helical IMRT by tomotherapy for bulky adrenocortical carcinoma operated with positive margins: a case report.

PubMed

Delmastro, Elena; Garibaldi, Elisabetta; Gabriele, Domenico; Bresciani, Sara; Cattari, Gabriella; Dia, Amalia Di; Manini, Claudia; Collura, Devis; Redda, Maria Grazia Ruo; Gabriele, Pietro

2016-11-11

Adrenocortical carcinoma (ACC) is a rare tumor in the adult. The main therapy is surgery but in some cases radiotherapy may be needed to control the disease locally. A patient with a surgically removed bulky ACC and pathologic finding of a positive margin was treated at our center by adjuvant mitotane and radiotherapy using an intensity-modulated radiation therapy (IMRT)/image-guided radiotherapy (IGRT) technique by tomotherapy. Dose prescriptions were 63 Gy on the surgical bed and 50.4 Gy on the lymphatic drainage in 28 sessions. Patient compliance was good with no evidence of acute or late toxicities. Thirty months after radiotherapy, the patient is alive without evidence of disease checked by 18F-fluorodeoxyglucose positron emission tomography/computed tomography and without any complication. In patients with adverse prognostic features, the delivery of adequate adjuvant radiotherapy doses with IMRT and daily IGRT is feasible and safe and could result in an improved outcome for patients with ACC.

Pelvic Nodal Radiotherapy in Patients With Unfavorable Intermediate and High-Risk Prostate Cancer: Evidence, Rationale, and Future Directions

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

Morikawa, Lisa K.; Memorial Sloan-Kettering Cancer Center; Roach, Mack, E-mail: mroach@radonc.ucsf.ed

2011-05-01

Over the past 15 years, there have been three major advances in the use of external beam radiotherapy in the management of men with clinically localized prostate made. They include: (1) image guided (IG) three-dimensional conformal/intensity modulated radiotherapy; (2) radiation dose escalation; and (3) androgen deprivation therapy. To date only the last of these three advances have been shown to improve overall survival. The presence of occult pelvic nodal involvement could explain the failure of increased conformality and dose escalation to prolong survival, because the men who appear to be at the greatest risk of death from clinically localized prostatemore » cancer are those who are likely to have lymph node metastases. This review discusses the evidence for prophylactic pelvic nodal radiotherapy, including the key trials and controversies surrounding this issue.« less

Influence of (11)C-choline PET/CT on radiotherapy planning in prostate cancer.

PubMed

López, Escarlata; Lazo, Antonio; Gutiérrez, Antonio; Arregui, Gregorio; Núñez, Isabel; Sacchetti, Antonio

2015-01-01

To evaluate the influence of (11)C-choline PET/CT on radiotherapy planning in prostate cancer patients. Precise information on the extension of prostate cancer is crucial for the choice of an appropriate therapeutic strategy. (11)C-choline positron emission tomography ((11)C-choline PET/CT) has two roles in radiation oncology (RT): (1) patient selection for treatment and (2) target volume selection and delineation. In conjunction with high-accuracy techniques, it might offer an opportunity of dose escalation and better tumour control while sparing healthy tissues. We carried out a retrospective study in order to analyse RT planning modification based on (11)C-choline PET/CT in 16 prostate cancer patients. Patients were treated with hypofractionated step-and-shoot Intensity Modulated Radiotherapy (IMRT), or Volumetric Modulated Arc Therapy (VMAT), and a daily cone-beam CT for Image Guided Radiation Therapy (IGRT). All patients underwent a (11)C-choline-PET/CT scan prior to radiotherapy. In 37.5% of cases, a re-delineation and new dose prescription occurred. Data show good preliminary clinical results in terms of biochemical control and toxicity. No gastrointestinal (GI)/genitourinary (GU) grade III toxicities were observed after a median follow-up of 9.5 months. In our experience, concerning the treatment of prostate cancer (PCa), (11)C-choline PET/CT may be helpful in radiotherapy planning, either for dose escalation or exclusion of selected sites.

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

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

Parker, William; Filion, Edith; Roberge, David

2007-09-01

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

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

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

Madani, Indira; Duthoy, Wim; Derie, Cristina R.N.

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 appliedmore » 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.« less

Dosimetric predictors of acute hematologic toxicity in cervical cancer patients treated with concurrent cisplatin and intensity-modulated pelvic radiotherapy

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

Mell, Loren K.; Kochanski, Joel D.; Department of Radiation and Cellular Oncology, University of Illinois at Chicago, Chicago, IL

Purpose: To identify dosimetric parameters associated with acute hematologic toxicity (HT) and chemotherapy delivery in cervical cancer patients undergoing concurrent chemotherapy and intensity-modulated pelvic radiotherapy. Methods and Materials: We analyzed 37 cervical cancer patients receiving concurrent cisplatin (40 mg/m{sup 2}/wk) and intensity-modulated pelvic radiotherapy. Pelvic bone marrow (BM) was contoured for each patient and divided into three subsites: lumbosacral spine, ilium, and lower pelvis. The volume of each region receiving 10, 20, 30, and {>=}40 Gy (V{sub 1}, V{sub 2}, V{sub 3}, and V{sub 4}, respectively) was calculated. HT was graded according to Radiation Therapy Oncology Group system. Multivariate regressionmore » models were used to test associations between dosimetric parameters and HT and chemotherapy delivery. Results: Increased pelvic BM V{sub 1} (BM-V{sub 1}) was associated with an increased Grade 2 or worse leukopenia and neutropenia (odds ratio [OR], 2.09; 95% confidence interval [CI], 1.24-3.53; p = 0.006; and OR, 1.41; 95% CI, 1.02-1.94; p = 0.037, respectively). Patients with BM-V{sub 1} {>=}90% had higher rates of Grade 2 or worse leukopenia and neutropenia than did patients with BM-V{sub 1} <90% (11.1% vs. 73.7%, p < 0.01; and 5.6% vs. 31.6%, p = 0.09) and were more likely to have chemotherapy held on univariate (16.7% vs. 47.4%, p = 0.08) and multivariate (OR, 32.2; 95% CI, 1.67-622; p = 0.02) analysis. No associations between HT and V{sub 3} and V{sub 4} were observed. Dosimetric parameters involving the lumbosacral spine and lower pelvis had stronger associations with HT than did those involving the ilium. Conclusion: The volume of pelvic BM receiving low-dose radiation is associated with HT and chemotherapy delivery in cervical cancer patients undergoing concurrent chemoradiotherapy.« less

Intensity-modulated radiotherapy as primary treatment for prostate cancer: acute toxicity in 114 patients.

PubMed

De Meerleer, Gert; Vakaet, Luc; Meersschout, Sabine; Villeirs, Geert; Verbaeys, Antony; Oosterlinck, Wim; De Neve, Wilfried

2004-11-01

Dose escalation improves local control in prostate cancer. At Ghent University Hospital, intensity-modulated radiotherapy (IMRT) is used to increase the dose to the prostate and/or seminal vesicles. We report on acute toxicity in 114 patients who received IMRT for prostate cancer. Intensity-modulated radiotherapy was initiated after approval of our ethics committee. A class solution was used to plan all cases. Three beams (gantry 0 degrees , 116 degrees , and 244 degrees ) and anatomy-based segmentation were used to create an intensity-modulated dose distribution. Maximal rectal dose was set at 2 Gy per fraction. Detailed dose-volume histograms for all relevant structures were present. For all patients, we determined the pretreatment morbidity by a detailed preradiotherapy, in-house developed symptom scale. All patients were treated with 18 MV photons of an Elekta linear accelerator. Patients were seen on a weekly basis during treatment, and 1 month (M1) and 3 months (M3) thereafter. The registration of acute toxicity was standardized by a fixed questionnaire. The Radiation Therapy Oncology Group (RTOG) toxicity scale served as a basis, but additional symptoms, such as rectal blood loss, urgency, and incontinence, were scored as well. All 114 IMRT plans were delivered successfully without any interruption or technical problem. Daily treatment time was always less than 8 min and less than 6 min in 90% of the cases. Grade 1 and Grade 2 gastrointestinal (GI) toxicities were observed in 44% and 29% of the patients, respectively, during the whole period. If only the RTOG scale was used, Grade 1 and Grade 2 GI toxicities were noted in 39% and 27% of the patients, respectively, leaving 34% free of acute RTOG-scaled toxicity. Grade 3 genitourinary (GU) toxicity was seen in 8 patients (7%), all but 1 during treatment. Grade 2 and Grade 1 GU toxicities were seen in 36% and 47% of the patients, respectively, leaving only 10% free of acute GU toxicity. Anatomy-based IMRT to treat prostate cancer is incorporated into our daily routine without any problem. Acute toxicity is very low. Most of the recorded symptoms decrease over time, except for GI urgency and incontinence. The incorporation of additional symptoms makes the scoring more detailed.

Current role of modern radiotherapy techniques in the management of breast cancer

PubMed Central

Ozyigit, Gokhan; Gultekin, Melis

2014-01-01

Breast cancer is the most common type of malignancy in females. Advances in systemic therapies and radiotherapy (RT) provided long survival rates in breast cancer patients. RT has a major role in the management of breast cancer. During the past 15 years several developments took place in the field of imaging and irradiation techniques, intensity modulated RT, hypofractionation and partial-breast irradiation. Currently, improvements in the RT technology allow us a subsequent decrease in the treatment-related complications such as fibrosis and long-term cardiac toxicity while improving the loco-regional control rates and cosmetic results. Thus, it is crucial that modern radiotherapy techniques should be carried out with maximum care and efficiency. Several randomized trials provided evidence for the feasibility of modern radiotherapy techniques in the management of breast cancer. However, the role of modern radiotherapy techniques in the management of breast cancer will continue to be defined by the mature results of randomized trials. Current review will provide an up-to-date evidence based data on the role of modern radiotherapy techniques in the management of breast cancer. PMID:25114857

Optimization of beam orientation in radiotherapy using planar geometry

NASA Astrophysics Data System (ADS)

Haas, O. C. L.; Burnham, K. J.; Mills, J. A.

1998-08-01

This paper proposes a new geometrical formulation of the coplanar beam orientation problem combined with a hybrid multiobjective genetic algorithm. The approach is demonstrated by optimizing the beam orientation in two dimensions, with the objectives being formulated using planar geometry. The traditional formulation of the objectives associated with the organs at risk has been modified to account for the use of complex dose delivery techniques such as beam intensity modulation. The new algorithm attempts to replicate the approach of a treatment planner whilst reducing the amount of computation required. Hybrid genetic search operators have been developed to improve the performance of the genetic algorithm by exploiting problem-specific features. The multiobjective genetic algorithm is formulated around the concept of Pareto optimality which enables the algorithm to search in parallel for different objectives. When the approach is applied without constraining the number of beams, the solution produces an indication of the minimum number of beams required. It is also possible to obtain non-dominated solutions for various numbers of beams, thereby giving the clinicians a choice in terms of the number of beams as well as in the orientation of these beams.

Evaluation of a mixed beam therapy for post-mastectomy breast cancer patients: bolus electron conformal therapy combined with intensity modulated photon radiotherapy and volumetric modulated photon arc therapy.

PubMed

Zhang, Rui; Heins, David; Sanders, Mary; Guo, Beibei; Hogstrom, Kenneth

2018-05-10

The purpose of this study was to assess the potential benefits and limitations of a mixed beam therapy, which combined bolus electron conformal therapy (BECT) with intensity modulated photon radiotherapy (IMRT) and volumetric modulated photon arc therapy (VMAT), for left-sided post-mastectomy breast cancer patients. Mixed beam treatment plans were produced for nine post-mastectomy radiotherapy (PMRT) patients previously treated at our clinic with VMAT alone. The mixed beam plans consisted of 40 Gy to the chest wall area using BECT, 40 Gy to the supraclavicular area using parallel opposed IMRT, and 10 Gy to the total planning target volume (PTV) by optimizing VMAT on top of the BECT+IMRT dose distribution. The treatment plans were created in a commercial treatment planning system (TPS), and all plans were evaluated based on PTV coverage, dose homogeneity index (DHI), conformity index (CI), dose to organs at risk (OARs), normal tissue complication probability (NTCP), and secondary cancer complication probability (SCCP). The standard VMAT alone planning technique was used as the reference for comparison. Both techniques produced clinically acceptable PMRT plans but with a few significant differences: VMAT showed significantly better CI (0.70 vs. 0.53, p < 0.001) and DHI (0.12 vs. 0.20, p < 0.001) over mixed beam therapy. For normal tissues, mixed beam therapy showed better OAR sparing and significantly reduced NTCP for cardiac mortality (0.23% vs. 0.80%, p = 0.01) and SCCP for contralateral breast (1.7% vs. 3.1% based on linear model, and 1.2% vs. 1.9% based on linear-exponential model, p < 0.001 in both cases), but showed significantly higher mean (50.8 Gy vs. 49.3 Gy, p < 0.001) and maximum skin doses (59.7 Gy vs. 53.3 Gy, p < 0.001) compared with VMAT. Patients with more tissue (minimum distance between the distal PTV surface and lung approximately > 0.5 cm and volume of tissue between the distal PTV surface and heart or lung approximately > 250 cm 3 ) between distal PTV surface and lung may benefit the most from mixed beam therapy. This work has demonstrated that mixed beam therapy (BECT+IMRT : VMAT = 4 : 1) produces clinically acceptable plans having reduced OAR doses and risks of side effects compared with VMAT. Even though VMAT alone produces more homogenous and conformal dose distributions, mixed beam therapy remains as a viable option for treating post-mastectomy patients, possibly leading to reduced normal tissue complications. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Comparison of the helical tomotherapy against the multileaf collimator-based intensity-modulated radiotherapy and 3D conformal radiation modalities in lung cancer radiotherapy

PubMed Central

Mavroidis, P; Shi, C; Plataniotis, G A; Delichas, M G; Costa Ferreira, B; Rodriguez, S; Lind, B K; Papanikolaou, N

2011-01-01

Objectives The aim of this study was to compare three-dimensional (3D) conformal radiotherapy and the two different forms of IMRT in lung cancer radiotherapy. Methods Cases of four lung cancer patients were investigated by developing a 3D conformal treatment plan, a linac MLC-based step-and-shoot IMRT plan and an HT plan for each case. With the use of the complication-free tumour control probability (P+) index and the uniform dose concept as the common prescription point of the plans, the different treatment plans were compared based on radiobiological measures. Results The applied plan evaluation method shows the MLC-based IMRT and the HT treatment plans are almost equivalent over the clinically useful dose prescription range; however, the 3D conformal plan inferior. At the optimal dose levels, the 3D conformal treatment plans give an average P+ of 48.1% for a effective uniform dose to the internal target volume (ITV) of 62.4 Gy, whereas the corresponding MLC-based IMRT treatment plans are more effective by an average ΔP+ of 27.0% for a Δ effective uniform dose of 16.3 Gy. Similarly, the HT treatment plans are more effective than the 3D-conformal plans by an average ΔP+ of 23.8% for a Δ effective uniform dose of 11.6 Gy. Conclusion A radiobiological treatment plan evaluation can provide a closer association of the delivered treatment with the clinical outcome by taking into account the dose–response relations of the irradiated tumours and normal tissues. The use of P – effective uniform dose diagrams can complement the traditional tools of evaluation to compare and effectively evaluate different treatment plans. PMID:20858664

Dosimetric effect of Elekta Beam Modulator micromultileaf in three-dimensional conformal radiotherapy and intensity-modulated radiotherapy for prostate cancer

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

Carosi, Alessandra, E-mail: alessandra.carosi@katamail.com; Ingrosso, Gianluca; Ponti, Elisabetta

2014-07-01

The purpose of this study is to analyze the dosimetric effect of Elekta Beam Modulator in 3-dimensional conformal radiation therapy (3DCRT) and in intensity-modulated radiation therapy (IMRT) for localized prostate cancer. We compared treatment plans developed with 2 different Elekta multileaf collimators (MLC): Beam Modulator micro-MLC (mMLC) (4-mm leaf width at the isocenter) and standard MLC (10-mm leaf width at the isocenter). The comparison was performed for 15 patients with localized prostate cancer in 3DCRT and IMRT delivery; a total of 60 treatment plans were processed. The dose-volume histograms were used to provide the quantitative comparison between plans. In particular,more » we analyzed differences between rectum and bladder sparing in terms of a set of appropriate Vx (percentage of organ at risk [OAR] volume receiving the x dose) and differences between target conformity and coverage in terms of coverage factor and conformation number. Our analysis demonstrates that in 3DCRT there is an advantage in the use of Elekta Beam Modulator mMLC in terms of organ sparing; in particular, a significant decrease in rectal V{sub 60} and V{sub 50} (p = 0.001) and in bladder V{sub 70} and V{sub 65} (p = 0.007 and 0.002, respectively) was found. Moreover, a better target dose conformity was obtained (p = 0.002). IMRT plans comparison demonstrated no significant differences between the use of the 4 or 10-mm MLCs. Our analysis shows that in 3DCRT the use of the Elekta Beam Modulator mMLC gives a gain in target conformity and in OARs dose sparing whereas in IMRT plans there is no advantage.« less

4D-Listmode-PET-CT and 4D-CT for optimizing PTV margins in gastric lymphoma : Determination of intra- and interfractional gastric motion.

PubMed

Reinartz, Gabriele; Haverkamp, Uwe; Wullenkord, Ramona; Lehrich, Philipp; Kriz, Jan; Büther, Florian; Schäfers, Klaus; Schäfers, Michael; Eich, Hans Theodor

2016-05-01

New imaging protocols for radiotherapy in localized gastric lymphoma were evaluated to optimize planning target volume (PTV) margin and determine intra-/interfractional variation of the stomach. Imaging of 6 patients was explored prospectively. Intensity-modulated radiotherapy (IMRT) planning was based on 4D/3D imaging of computed tomography (CT) and positron-emission tomography (PET)-CT. Static and motion gross tumor volume (sGTV and mGTV, respectively) were distinguished by defining GTV (empty stomach), clinical target volume (CTV = GTV + 5 mm margin), PTV (GTV + 10/15/20/25 mm margins)  plus paraaortic lymph nodes and proximal duodenum. Overlap of 4D-Listmode-PET-based mCTV with 3D-CT-based PTV (increasing margins) and V95/D95 of mCTV were evaluated. Gastric shifts were determined using online cone-beam CT. Dose contribution to organs at risk was assessed. The 4D data demonstrate considerable intra-/interfractional variation of the stomach, especially along the vertical axis. Conventional 3D-CT planning utilizing advancing PTV margins of 10/15/20/25 mm resulted in rising dose coverage of mCTV (4D-Listmode-PET-Summation-CT) and rising D95 and V95 of mCTV. A PTV margin of 15 mm was adequate in 3 of 6 patients, a PTV margin of 20 mm was adequate in 4 of 6 patients, and a PTV margin of 25 mm was adequate in 5 of 6 patients. IMRT planning based on 4D-PET-CT/4D-CT together with online cone-beam CT is advisable to individualize the PTV margin and optimize target coverage in gastric lymphoma.

Carotid-Sparing Intensity-Modulated Radiotherapy for Early-Stage Squamous Cell Carcinoma of the True Vocal Cord

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

Chera, Bhishamjit S.; Amdur, Robert J., E-mail: amdurr@shands.ufl.ed; Morris, Christopher G.

2010-08-01

Purpose: To compare radiation doses to carotid arteries among various radiotherapy techniques for treatment of early-stage squamous cell carcinoma (SCC) of the true vocal cords. Methods and Materials: Five patients were simulated using computed tomography (CT). Clinical and planning target volumes (PTV) were created for bilateral and unilateral stage T1 vocal cord cancers. Planning risk volumes for the carotid arteries and spinal cord were delineated. For each patient, three treatment plans were designed for bilateral and unilateral target volumes: opposed laterals (LATS), three-dimensional conformal radiotherapy (3DCRT), and intensity-modulated radiotherapy (IMRT), for a total of 30 plans. More than 95% ofmore » the PTV received the prescription dose (63Gy at 2.25 Gy per treatment). Results: Carotid dose was lowest with IMRT. With a bilateral vocal cord target, the median carotid dose was 10Gy with IMRT vs. 25 Gy with 3DCRT and 38 Gy with LATS (p < 0.05); with a unilateral target, the median carotid dose was 4 Gy with IMRT vs. 19 Gy with 3DCRT and 39 Gy with LATS (p < 0.05). The dosimetric tradeoff with IMRT is a small area of high dose in the PTV. The worst heterogeneity results were at a maximum point dose of 80 Gy (127%) in a unilateral target that was close to the carotid. Conclusions: There is no question that IMRT can reduce the dose to the carotid arteries in patients with early-stage vocal cord cancer. The question is whether the potential advantage of reducing the carotid dose outweighs the risk of tumor recurrence due to contouring errors and organ motion and the risk of complications from dose heterogeneity.« less

The impact of introducing intensity modulated radiotherapy into routine clinical practice.

PubMed

Miles, Elizabeth A; Clark, Catharine H; Urbano, M Teresa Guerrero; Bidmead, Margaret; Dearnaley, David P; Harrington, Kevin J; A'Hern, Roger; Nutting, Christopher M

2005-12-01

Intensity modulated radiotherapy (IMRT) at the Royal Marsden Hospital London was introduced in July 2001. Treatment delivery was dynamic using a single-phase technique. Concerns were raised regarding increased clinical workload due to introduction of new technology. The potential increased use of resources was assessed. IMRT patient selection was within guidelines of clinical trials and included patients undergoing prostate plus pelvic lymph node (PPN) irradiation and head and neck cancer (HNC) treatment. Patient planning, quality assurance and treatment times were collected for an initial IMRT patient group. A comparative group of patients with advanced HNC undergoing two- or three-phase conventional radiotherapy, requiring matched photon and electron fields, were also timed. The median overall total planning time for IMRT was greater for HNC patients compared to the PPN cohort. For HNC the overall IMRT planning time was significantly longer than for conventional. The median treatment time for conventional two- or three-phase HNC treatments, encompassing similar volumes to those treated with IMRT, was greater than that for the IMRT HNC patient cohort. A reduction in radiographer man hours per patient of 4.8h was recorded whereas physics time was increased by 4.9h per patient. IMRT currently increases overall planning time. Additional clinician input is required for target volume localisation. Physics time is increased, a significant component of this being patient specific QA. Radiographer time is decreased. For HNC a single phase IMRT treatment has proven to be more efficient than a multiple phase conventional treatment. IMRT has been integrated smoothly and efficiently into the existing treatment working day. This preliminary study suggests that IMRT could be a routine treatment with efficient use of current radiotherapy resources.

Decreasing Temporal Lobe Dose With Five-Field Intensity-Modulated Radiotherapy for Treatment of Pituitary Macroadenomas

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

Parhar, Preeti K.; Duckworth, Tamara; Shah, Parinda

2010-10-01

Purpose: To compare temporal lobe dose delivered by three pituitary macroadenoma irradiation techniques: three-field three-dimensional conformal radiotherapy (3D-CRT), three-field intensity-modulated radiotherapy (3F IMRT), and a proposed novel alternative of five-field IMRT (5F IMRT). Methods and Materials: Computed tomography-based external beam radiotherapy planning was performed for 15 pituitary macroadenoma patients treated at New York University between 2002 and 2007 using: 3D-CRT (two lateral, one midline superior anterior oblique [SAO] beams), 3F IMRT (same beam angles), and 5F IMRT (same beam angles with additional right SAO and left SAO beams). Prescription dose was 45 Gy. Target volumes were: gross tumor volume (GTV)more » = macroadenoma, clinical target volume (CTV) = GTV, and planning target volume = CTV + 0.5 cm. Structure contouring was performed by two radiation oncologists guided by an expert neuroradiologist. Results: Five-field IMRT yielded significantly decreased temporal lobe dose delivery compared with 3D-CRT and 3F IMRT. Temporal lobe sparing with 5F IMRT was most pronounced at intermediate doses: mean V25Gy (% of total temporal lobe volume receiving {>=}25 Gy) of 13% vs. 28% vs. 29% for right temporal lobe and 14% vs. 29% vs. 30% for left temporal lobe for 5F IMRT, 3D-CRT, and 3F IMRT, respectively (p < 10{sup -7} for 5F IMRT vs. 3D-CRT and 5F IMRT vs. 3F IMRT). Five-field IMRT plans did not compromise target coverage, exceed normal tissue dose constraints, or increase estimated brain integral dose. Conclusions: Five-field IMRT irradiation technique results in a statistically significant decrease in the dose to the temporal lobes and may thus help prevent neurocognitive sequelae in irradiated pituitary macroadenoma patients.« less

DEMAT: A multi-institutional dosimetry audit of rotational and static intensity-modulated radiotherapy.

PubMed

Lafond, Caroline; Chiavassa, Sophie; Bertaut, Cindy; Boussion, Nicolas; Chapel, Nathalie; Chapron, Lucie; Coste, Frédéric; Crespin, Sylvain; Dy, Gilles; Faye, Papa Abdoulaye; Leleu, Cyril; Bouvier, Jeanne; Madec, Ludovic; Mesgouez, Jérôme; Palisson, Jérémy; Vela, Anthony; Delpon, Grégory

2016-05-01

Static beam intensity-modulated-radiation-therapy (IMRT) and/or Volumetric-Modulated-Arc-Therapy (VMAT) are now available in many regional radiotherapy departments. The aim of this multi-institutional audit was to design a new methodology based on radiochromic films to perform an independent quality control. A set of data were sent to all participating centres for two clinical localizations: prostate and Head and Neck (H&N) cancers. The agreement between calculations and measurements was verified in the Octavius phantom (PTW) by point measurements using ionization chambers and by 2D measurements using EBT3 radiochromic films. Due to uncertainties in the whole procedure, criteria were set to 5% and 3% in local dose and 3mm in distance excluding doses lower than 10% of the maximum doses. No normalization point or area was used for the quantitative analysis. 13 radiotherapy centres participated in this audit involving 28 plans (12 IMRT, 16 VMAT). For point measurements, mean errors were -0.18±1.54% and 0.00±1.58% for prostate and H&N cases respectively. For 2D measurements with 5%/3mm criteria, gamma map analysis showed a pixel pass rate higher than 95% for prostate and H&N. Mean gamma index was lower than 0.4 for prostate and 0.5 for H&N. Both techniques yielded similar results. This study showed the feasibility of an independent quality control by peers for conventional IMRT and VMAT. Results from all participating centres were found to be in good agreement. This regional study demonstrated the feasibility of our new methodology based on radiochromic films without dose normalization on a specific point. Copyright © 2016 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Dosimetric comparison using different multileaf collimeters in intensity-modulated radiotherapy for upper thoracic esophageal cancer.

PubMed

Gong, Youling; Wang, Shichao; Zhou, Lin; Liu, Yongmei; Xu, Yong; Lu, You; Bai, Sen; Fu, Yuchuan; Xu, Qingfeng; Jiang, Qingfeng

2010-07-15

To study the impacts of multileaf collimators (MLC) width [standard MLC width of 10 mm (sMLC) and micro-MLC width of 4 mm (mMLC)] in the intensity-modulated radiotherapy (IMRT) planning for the upper thoracic esophageal cancer (UTEC). 10 patients with UTEC were retrospectively planned with the sMLC and the mMLC. The monitor unites (MUs) and dose volume histogram-based parameters [conformity index (CI) and homogeneous index (HI)] were compared between the IMRT plans with sMLC and with mMLC. The IMRT plans with the mMLC were more efficient (average MUs: 703.1 +/- 68.3) than plans with the sMLC (average MUs: 833.4 +/- 73.8) (p < 0.05). Also, compared to plans with the sMLC, the plans with the mMLC showed advantages in dose coverage of the planning gross tumor volume (Pgtv) (CI 0.706 +/- 0.056/HI 1.093 +/- 0.021) and the planning target volume (PTV) (CI 0.707 +/- 0.029/HI 1.315 +/- 0.013) (p < 0.05). In addition, the significant dose sparing in the D5 (3260.3 +/- 374.0 vs 3404.5 +/- 374.4)/gEUD (1815.1 +/- 281.7 vs 1849.2 +/- 297.6) of the spinal cord, the V10 (33.2 +/- 6.5 vs 34.0 +/- 6.7), V20 (16.0 +/- 4.6 vs 16.6 +/- 4.7), MLD (866.2 +/- 174.1 vs 887.9 +/- 172.1) and gEUD (938.6 +/- 175.2 vs 956.8 +/- 171.0) of the lungs were observed in the plans with the mMLC, respectively (p < 0.05). Comparing to the sMLC, the mMLC not only demonstrated higher efficiencies and more optimal target coverage, but also considerably improved the dose sparing of OARs in the IMRT planning for UTEC.

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

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

Hagan, A; Modiri, A; Sawant, A

Purpose: True 4D IMRT planning, based on simultaneous spatiotemporal optimization has been shown to significantly improve plan quality in lung radiotherapy. However, the high computational complexity associated with such planning represents a significant barrier to widespread clinical deployment. We introduce an early prototype GPU-enabled Eclipse workstation for inverse planning. To our knowledge, this is the first GPUintegrated Eclipse system demonstrating the potential for clinical translation of GPU computing on a major commercially-available TPS. Methods: The prototype system comprised of four NVIDIA Tesla K80 GPUs, with a maximum processing capability of 8.5 Tflops per K80 card. The system architecture consisted ofmore » three key modules: (i) a GPU-based inverse planning module using a highly-parallelizable, swarm intelligence-based global optimization algorithm, (ii) a GPU-based open-source b-spline deformable image registration module, Elastix, and (iii) a CUDA-based data management module. For evaluation, aperture fluence weights in an IMRT plan were optimized over 9 beams,166 apertures and 10 respiratory phases (14940 variables) for a lung cancer case (GTV = 95 cc, right lower lobe, 15 mm cranio-caudal motion). Sensitivity of the planning time and memory expense to parameter variations was quantified. Results: GPU-based inverse planning was significantly accelerated compared to its CPU counterpart (36 vs 488 min, for 10 phases, 10 search agents and 10 iterations). The optimized IMRT plan significantly improved OAR sparing compared to the original internal target volume (ITV)-based clinical plan, while maintaining prescribed tumor coverage. The dose-sparing improvements were: Esophagus Dmax 50%, Heart Dmax 42% and Spinal cord Dmax 25%. Conclusion: Our early prototype system demonstrates that through massive parallelization, computationally intense tasks such as 4D treatment planning can be accomplished in clinically feasible timeframes. With further optimization, such systems are expected to enable the eventual clinical translation of higher-dimensional and complex treatment planning strategies to significantly improve plan quality. This work was partially supported through research funding from National Institutes of Health (R01CA169102) and Varian Medical Systems, Palo Alto, CA, USA.« less

Epithelioid hemangioendothelioma of the spine treated with RapidArc volumetric-modulated radiotherapy

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

Guy, Jean-Baptiste; Trone, Jane-Chloé; Chargari, Cyrus

2014-10-01

Radiotherapy for epithelioid hemangioendothelioma (EHE) using volumetric intensity-modulated arc radiotherapy (VMAT). A 48-year-old woman was referred for curative irradiation of a vertebral EHE after failure of surgery. A comparison between VMAT and conventional conformal tridimensional (3D) dosimetry was performed and potential advantage of VMAT for sparing critical organs from irradiation's side effects was discussed. The total delivered dose on the planning target volume was 54 Gy in 27 fractions. The patient was finally treated with VMAT. The tolerance was excellent. There was no acute toxicity, including no increase in pain. With a follow-up of 18 months, no delayed toxicity wasmore » reported. The clinical response consisted of a decrease in the dorsal pain. The D{sub max} for the spinal cord was reduced from 55 Gy (3D-radiotherapy [RT]) (which would be an unacceptable dose to the spine because of the risk of myelopathy) to 42.8 Gy (VMAT), which remains below the recommended dose threshold (45 Gy). The dose delivered to 20% of organ volume (D{sub 20}) was reduced from 47 Gy (3D-RT) to 3 Gy (VMAT) for the spinal cord. The study shows that VMAT allows the delivery of curative treatment for vertebral EHEs because of critical organ sparing.« less

Quality of Life After Hypofractionated Concomitant Intensity-Modulated Radiotherapy Boost for High-Risk Prostate Cancer

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

Quon, Harvey; Department of Radiation Oncology, University of Toronto, Toronto, ON; Cheung, Patrick C.F., E-mail: patrick.cheung@sunnybrook.ca

Purpose: To evaluate the change in health-related quality of life (QOL) of patients with high-risk prostate cancer treated using hypofractionated radiotherapy combined with long-term androgen deprivation therapy. Methods and Materials: A prospective Phase I-II study enrolled patients with any of the following: clinical Stage T3 disease, prostate-specific antigen level {>=}20 ng/mL, or Gleason score 8-10. Radiotherapy consisted of 45 Gy (1.8 Gy per fraction) to the pelvic lymph nodes with a concomitant 22.5 Gy intensity-modulated radiotherapy boost to the prostate, for a total of 67.5 Gy (2.7 Gy per fraction) in 25 fractions over 5 weeks. Daily image guidance wasmore » performed using three gold seed fiducials. Quality of life was measured using the Expanded Prostate Cancer Index Composite (EPIC), a validated tool that assesses four primary domains (urinary, bowel, sexual, and hormonal). Results: From 2004 to 2007, 97 patients were treated. Median follow-up was 39 months. Compared with baseline, at 24 months there was no statistically significant change in the mean urinary domain score (p = 0.99), whereas there were decreases in the bowel (p < 0.01), sexual (p < 0.01), and hormonal (p < 0.01) domains. The proportion of patients reporting a clinically significant difference in EPIC urinary, bowel, sexual, and hormonal scores at 24 months was 27%, 31%, 55%, and 60%, respectively. However, moderate and severe distress related to these symptoms was minimal, with increases of only 3% and 5% in the urinary and bowel domains, respectively. Conclusions: Hypofractionated radiotherapy combined with long-term androgen deprivation therapy was well tolerated. Although there were modest rates of clinically significant patient-reported urinary and bowel toxicity, most of this caused only mild distress, and moderate and severe effects on QOL were limited. Additional follow-up is ongoing to characterize long-term QOL.« less

Visibility of an iron-containing fiducial marker in magnetic resonance imaging for high-precision external beam prostate radiotherapy.

PubMed

Tanaka, Osamu; Komeda, Hisao; Hirose, Shigeki; Taniguchi, Takuya; Ono, Kousei; Matsuo, Masayuki

2017-11-29

Visualization of fiducial gold markers is critical for registration on computed tomography (CT) and magnetic resonance imaging (MRI) for imaging-guided radiotherapy. Although larger markers provide better visualization on MRI, they tend to generate artifacts on CT. MRI is strongly influenced by the presence of metals, such as iron, in the body. Here we compared efficacies of a 0.5% iron-containing gold marker (GM) and a traditional non-iron-containing marker. Twenty-seven patients underwent CT/MRI fusion-based intensity-modulated radiotherapy. Markers were placed by urologists under local anesthesia. Gold Anchor (GA; diameter: 0.28 mm; length: 10 mm), an iron-containing marker, was placed on the right side of the prostate using a 22-G needle and VISICOIL (VIS; diameter: 0.35 mm; length: 10 mm), a non-iron-containing marker, was placed on the left side using a 19-G needle. T2*-weighted images MRI sequences were obtained. Two radiation oncologists and a radiation technologist evaluated and assigned scores for visual quality on a five-point scale (1, poor; 5, best visibility). Artifact generation on CT was slightly greater with GA than with VIS. The mean marker visualization scores on MRI of all three observers were significantly superior for GA than for VIS (3.5 vs 3.2, 3.9 vs 3.2, and 4.0 vs 2.9). The actual size of the spherical GA was about 2 mm in diameter, but the signal void on MRI was approximately 5 mm. Although both markers were well visualized and can be recommended clinically, the results suggest that GA has some subtle advantages for quantitative visualization that could prove useful in certain situations of stereotactic body radiotherapy and intensity-modulated radiotherapy. © 2017 John Wiley & Sons Australia, Ltd.

Protons Offer Reduced Normal-Tissue Exposure for Patients Receiving Postoperative Radiotherapy for Resected Pancreatic Head Cancer

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

Nichols, Romaine C., E-mail: rnichols@floridaproton.org; Huh, Soon N.; Prado, Karl L.

2012-05-01

Purpose: To determine the potential role for adjuvant proton-based radiotherapy (PT) for resected pancreatic head cancer. Methods and Materials: Between June 2008 and November 2008, 8 consecutive patients with resected pancreatic head cancers underwent optimized intensity-modulated radiotherapy (IMRT) treatment planning. IMRT plans used between 10 and 18 fields and delivered 45 Gy to the initial planning target volume (PTV) and a 5.4 Gy boost to a reduced PTV. PTVs were defined according to the Radiation Therapy Oncology Group 9704 radiotherapy guidelines. Ninety-five percent of PTVs received 100% of the target dose and 100% of the PTVs received 95% of themore » target dose. Normal tissue constraints were as follows: right kidney V18 Gy to <70%; left kidney V18 Gy to <30%; small bowel/stomach V20 Gy to <50%, V45 Gy to <15%, V50 Gy to <10%, and V54 Gy to <5%; liver V30 Gy to <60%; and spinal cord maximum to 46 Gy. Optimized two- to three-field three-dimensional conformal proton plans were retrospectively generated on the same patients. The team generating the proton plans was blinded to the dose distributions achieved by the IMRT plans. The IMRT and proton plans were then compared. A Wilcoxon paired t-test was performed to compare various dosimetric points between the two plans for each patient. Results: All proton plans met all normal tissue constraints and were isoeffective with the corresponding IMRT plans in terms of PTV coverage. The proton plans offered significantly reduced normal-tissue exposure over the IMRT plans with respect to the following: median small bowel V20 Gy, 15.4% with protons versus 47.0% with IMRT (p = 0.0156); median gastric V20 Gy, 2.3% with protons versus 20.0% with IMRT (p = 0.0313); and median right kidney V18 Gy, 27.3% with protons versus 50.5% with IMRT (p = 0.0156). Conclusions: By reducing small bowel and stomach exposure, protons have the potential to reduce the acute and late toxicities of postoperative chemoradiation in this setting.« less

Protons offer reduced normal-tissue exposure for patients receiving postoperative radiotherapy for resected pancreatic head cancer.

PubMed

Nichols, Romaine C; Huh, Soon N; Prado, Karl L; Yi, Byong Y; Sharma, Navesh K; Ho, Meng W; Hoppe, Bradford S; Mendenhall, Nancy P; Li, Zuofeng; Regine, William F

2012-05-01

To determine the potential role for adjuvant proton-based radiotherapy (PT) for resected pancreatic head cancer. Between June 2008 and November 2008, 8 consecutive patients with resected pancreatic head cancers underwent optimized intensity-modulated radiotherapy (IMRT) treatment planning. IMRT plans used between 10 and 18 fields and delivered 45 Gy to the initial planning target volume (PTV) and a 5.4 Gy boost to a reduced PTV. PTVs were defined according to the Radiation Therapy Oncology Group 9704 radiotherapy guidelines. Ninety-five percent of PTVs received 100% of the target dose and 100% of the PTVs received 95% of the target dose. Normal tissue constraints were as follows: right kidney V18 Gy to <70%; left kidney V18 Gy to <30%; small bowel/stomach V20 Gy to <50%, V45 Gy to <15%, V50 Gy to <10%, and V54 Gy to <5%; liver V30 Gy to <60%; and spinal cord maximum to 46 Gy. Optimized two- to three-field three-dimensional conformal proton plans were retrospectively generated on the same patients. The team generating the proton plans was blinded to the dose distributions achieved by the IMRT plans. The IMRT and proton plans were then compared. A Wilcoxon paired t-test was performed to compare various dosimetric points between the two plans for each patient. All proton plans met all normal tissue constraints and were isoeffective with the corresponding IMRT plans in terms of PTV coverage. The proton plans offered significantly reduced normal-tissue exposure over the IMRT plans with respect to the following: median small bowel V20 Gy, 15.4% with protons versus 47.0% with IMRT (p = 0.0156); median gastric V20 Gy, 2.3% with protons versus 20.0% with IMRT (p = 0.0313); and median right kidney V18 Gy, 27.3% with protons versus 50.5% with IMRT (p = 0.0156). By reducing small bowel and stomach exposure, protons have the potential to reduce the acute and late toxicities of postoperative chemoradiation in this setting. Copyright © 2012 Elsevier Inc. All rights reserved.

[18F]fluoroethylcholine-PET/CT imaging for radiation treatment planning of recurrent and primary prostate cancer with dose escalation to PET/CT-positive lymph nodes.

PubMed

Würschmidt, Florian; Petersen, Cordula; Wahl, Andreas; Dahle, Jörg; Kretschmer, Matthias

2011-05-01

At present there is no consensus on irradiation treatment volumes for intermediate to high-risk primary cancers or recurrent disease. Conventional imaging modalities, such as CT, MRI and transrectal ultrasound, are considered suboptimal for treatment decisions. Choline-PET/CT might be considered as the imaging modality in radiooncology to select and delineate clinical target volumes extending the prostate gland or prostate fossa. In conjunction with intensity modulated radiotherapy (IMRT) and imaged guided radiotherapy (IGRT), it might offer the opportunity of dose escalation to selected sites while avoiding unnecessary irradiation of healthy tissues. Twenty-six patients with primary (n = 7) or recurrent (n = 19) prostate cancer received Choline-PET/CT planned 3D conformal or intensity modulated radiotherapy. The median age of the patients was 65 yrs (range 45 to 78 yrs). PET/CT-scans with F18-fluoroethylcholine (FEC) were performed on a combined PET/CT-scanner equipped for radiation therapy planning. The majority of patients had intermediate to high risk prostate cancer. All patients received 3D conformal or intensity modulated and imaged guided radiotherapy with megavoltage cone beam CT. The median dose to primary tumours was 75.6 Gy and to FEC-positive recurrent lymph nodal sites 66,6 Gy. The median follow-up time was 28.8 months. The mean SUV(max) in primary cancer was 5,97 in the prostate gland and 3,2 in pelvic lymph nodes. Patients with recurrent cancer had a mean SUV(max) of 4,38. Two patients had negative PET/CT scans. At 28 months the overall survival rate is 94%. Biochemical relapse free survival is 83% for primary cancer and 49% for recurrent tumours. Distant disease free survival is 100% and 75% for primary and recurrent cancer, respectively. Acute normal tissue toxicity was mild in 85% and moderate (grade 2) in 15%. No or mild late side effects were observed in the majority of patients (84%). One patient had a severe bladder shrinkage (grade 4) after a previous treatment with TUR of the prostate and seed implantation. FEC-PET/CT planning could be helpful in dose escalation to lymph nodal sites of prostate cancer.

SU-E-T-355: A Comparative Study of Robotic and Linac-Based Stereotactitc Body Radiation Therapy for Lumbar Spinal Tumors

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

Bossart, E; Monterroso, M; Couto, M

Purpose: Dosimetrically compare CyberKnife (CK) and linac-based (LB) stereotactic body radiotherapy (SBRT) plans for lumbar spine. Methods: Ten patient plans with lumbar spine tumors treated with CK were selected and retrospectively optimized using three techniques: CK, volumetric modulated arc (VMAT, three arcs), and 9-field-intensity modulated radiotherapy (IMRT). For the LB plans, the target volume was expanded by 1mm to accommodate additional uncertainty in patient positioning. All plans were optimized to a prescription dose of 27Gy in 3 fractions covering 90% of the PTV. If the dose constraints to the cauda equina (cauda) were not met, the prescription dose was loweredmore » to 24Gy. Parameters evaluated included Paddick Conformity-Index (CI) and Gradient-Index (GI). A two-tailed paired t-test was used to establish statistically significant differences in cauda doses. Results: Target volumes for LB plans were on average 38% larger. In terms of the indices, the closer the index values to unity the steeper the dose falloff and the higher the dose conformity to the target. The results showed that LB plans were in general statistically superior to CK plans. The IMRT plan showed the best average gradient index of 2.995, with VMAT and CK GI values of 3.699 and 5.476, respectively. Similarly, the same trend occurs with the average CI results: 0.821, 0.814, and 0.758, corresponding to IMRT, VMAT, and CK. Notably, in one CK plan the target dose was reduced to 24Gy to meet cauda constraints. Additionally, there was a statistically significant dose difference for the cauda between the CK and LB plans. Conclusion: This study demonstrates that LB plans for lumbar spine SBRT can be as effective or even better than CK plans. Despite the expansion of the target volume, the LB plans did not demonstrate dosimetric inferiority. The LB plans Resultin 2-to-3 fold decrease of treatment time.« less

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

PubMed

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

2015-10-01

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

Study for reducing lung dose of upper thoracic esophageal cancer radiotherapy by auto-planning: volumetric-modulated arc therapy vs intensity-modulated radiation therapy.

PubMed

Chen, Hua; Wang, Hao; Gu, Hengle; Shao, Yan; Cai, Xuwei; Fu, Xiaolong; Xu, Zhiyong

2017-10-27

This study aimed to investigate the dosimetric differences and lung sparing between volumetric-modulated arc therapy (VMAT) and intensity-modulated radiation therapy (IMRT) in the treatment of upper thoracic esophageal cancer with T3N0M0 for preoperative radiotherapy by auto-planning (AP). Sixteen patient cases diagnosed with upper thoracic esophageal cancer T3N0M0 for preoperative radiotherapy were retrospectively studied, and 3 plans were generated for each patient: full arc VMAT AP plan with double arcs, partial arc VMAT AP plan with 6 partial arcs, and conventional IMRT AP plan. A simultaneous integrated boost with 2 levels was planned in all patients. Target coverage, organ at risk sparing, treatment parameters including monitor units and treatment time (TT) were evaluated. Wilcoxon signed-rank test was used to check for significant differences (p < 0.05) between datasets. VMAT plans (pVMAT and fVMAT) significantly reduced total lung volume treated above 20 Gy (V 20 ), 25 Gy (V 25 ), 30 Gy (V 30 ), 35 Gy (V 35 ), 40 Gy (V 40 ), and without increasing the value of V 10 , V 13 , and V 15 . For V 5 of total lung value, pVMAT was similar to aIMRT, and it was better than fVMAT. Both pVMAT and fVMAT improved the target dose coverage and significantly decreased maximum dose for the spinal cord, monitor unit, and TT. No significant difference was observed with respect to V 10 and V 15 of body. VMAT AP plan was a good option for treating upper thoracic esophageal cancer with T3N0M0, especially partial arc VMAT AP plan. It had the potential to effectively reduce lung dose in a shorter TT and with superior target coverage and dose homogeneity. Copyright © 2017 American Association of Medical Dosimetrists. Published by Elsevier Inc. All rights reserved.

SU-E-T-449: Hippocampal Sparing Radiotherapy Using Intensity Modulated Radiotherapy and Volumetric Modulated Arc Therapy

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

Moon, S; Kyung Hee University Hospital at Gangdong, Gangdong-gu; Kim, D

2015-06-15

Purpose: The hippocampus sparing during the cranial irradiation has become interesting because it may mitigate radiation-induced neurocognitive toxicity. Herein we report our preliminary study for sparing the hippocampus with and without tilling condition for patient with brain metastases. Methods: Ten patients previously treated with whole brain were reviewed. Five patients tilted the head to around 30 degrees and others were treated without tilting. Treatment plans of linear accelerator (Linac)-based volumetric modulated arc therapy (VMAT) and intensity modulated radiotherapy (IMRT) were generated for prescription dose of 30 Gy in 15 fractions. Hippocampal avoidance regions were created with 5-mm volumetric expansion aroundmore » the hippocampus. Whole brain, hippocampus and hippocampal avoidance volume were 1372cm3, 6cm3 and 30cm3 and hippocampal avoidance volume was 2.2% of the whole brain planned target volume in average. Organs at risk (OARs) are hippocampus, eyes, lens, and cochleae. Coverage index (CVI), conformity index (CI), homogeneity index (HI) and mean dose to OARs were used to compare dose characteristic of tilted and non-tilted cases. Results: In IMRT, when CI, CVI and HI of whole brain were 0.88, 0.09 and 0.98 in both tilted and non-tilted cases, absorbed dose of hippocampal avoidance volume in tilted cases were 10% lower than non-tilted cases. Doses in other OARs such as eyes, lens, and cochleae were also decreased about 20% when tilting the head. When CI, HI and CVI in VMAT were 0.9, 0.08 and 0.99, the dose-decreased ratio of OARs in both with and without tilting cases were almost the same with IMRT. But absolute dose of hippocampal avoidance volume in VMAT was 30% lower than IMRT. Conclusion: This study confirms that dose to hippocampus decreases if patients tilt the head. When treating the whole brain with head tilted, patients can acquire the same successful treatment Result and also preserve their valuable memory.« less

Clinical utility of RapidArc™ radiotherapy technology

PubMed Central

Infusino, Erminia

2015-01-01

RapidArc™ is a radiation technique that delivers highly conformal dose distributions through the complete rotation (360°) and speed variation of the linear accelerator gantry. This technique, called volumetric modulated arc therapy (VMAT), compared with conventional radiotherapy techniques, can achieve high-target volume coverage and sparing damage to normal tissues. RapidArc delivers precise dose distribution and conformity similar to or greater than intensity-modulated radiation therapy in a short time, generally a few minutes, to which image-guided radiation therapy is added. RapidArc has become a currently used technology in many centers, which use RapidArc technology to treat a large number of patients. Large and small hospitals use it to treat the most challenging cases, but more and more frequently for the most common cancers. The clinical use of RapidArc and VMAT technology is constantly growing. At present, a limited number of clinical data are published, mostly concerning planning and feasibility studies. Clinical outcome data are increasing for a few tumor sites, even if only a little. The purpose of this work is to discuss the current status of VMAT techniques in clinical use through a review of the published data of planning systems and clinical outcomes in several tumor sites. The study consisted of a systematic review based on analysis of manuscripts retrieved from the PubMed, BioMed Central, and Scopus databases by searching for the keywords “RapidArc”, “Volumetric modulated arc radiotherapy”, and “Intensity-modulated radiotherapy”. PMID:26648755

Monte Carlo treatment planning with modulated electron radiotherapy: framework development and application

NASA Astrophysics Data System (ADS)

Alexander, Andrew William

Within the field of medical physics, Monte Carlo radiation transport simulations are considered to be the most accurate method for the determination of dose distributions in patients. The McGill Monte Carlo treatment planning system (MMCTP), provides a flexible software environment to integrate Monte Carlo simulations with current and new treatment modalities. A developing treatment modality called energy and intensity modulated electron radiotherapy (MERT) is a promising modality, which has the fundamental capabilities to enhance the dosimetry of superficial targets. An objective of this work is to advance the research and development of MERT with the end goal of clinical use. To this end, we present the MMCTP system with an integrated toolkit for MERT planning and delivery of MERT fields. Delivery is achieved using an automated "few leaf electron collimator" (FLEC) and a controller. Aside from the MERT planning toolkit, the MMCTP system required numerous add-ons to perform the complex task of large-scale autonomous Monte Carlo simulations. The first was a DICOM import filter, followed by the implementation of DOSXYZnrc as a dose calculation engine and by logic methods for submitting and updating the status of Monte Carlo simulations. Within this work we validated the MMCTP system with a head and neck Monte Carlo recalculation study performed by a medical dosimetrist. The impact of MMCTP lies in the fact that it allows for systematic and platform independent large-scale Monte Carlo dose calculations for different treatment sites and treatment modalities. In addition to the MERT planning tools, various optimization algorithms were created external to MMCTP. The algorithms produced MERT treatment plans based on dose volume constraints that employ Monte Carlo pre-generated patient-specific kernels. The Monte Carlo kernels are generated from patient-specific Monte Carlo dose distributions within MMCTP. The structure of the MERT planning toolkit software and optimization algorithms are demonstrated. We investigated the clinical significance of MERT on spinal irradiation, breast boost irradiation, and a head and neck sarcoma cancer site using several parameters to analyze the treatment plans. Finally, we investigated the idea of mixed beam photon and electron treatment planning. Photon optimization treatment planning tools were included within the MERT planning toolkit for the purpose of mixed beam optimization. In conclusion, this thesis work has resulted in the development of an advanced framework for photon and electron Monte Carlo treatment planning studies and the development of an inverse planning system for photon, electron or mixed beam radiotherapy (MBRT). The justification and validation of this work is found within the results of the planning studies, which have demonstrated dosimetric advantages to using MERT or MBRT in comparison to clinical treatment alternatives.

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

Sveistrup, Joen; af Rosenschöld, Per Munck; Deasy, Joseph O; Oh, Jung Hun; Pommer, Tobias; Petersen, Peter Meidahl; Engelholm, Svend Aage

2014-02-04

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). 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. 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. 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.

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

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

Zhao, J; Wang, J; Zhang, Z

2014-06-01

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

Comparative planning evaluation of intensity-modulated radiotherapy techniques for complex lung cancer cases.

PubMed

Yartsev, Slav; Chen, Jeff; Yu, Edward; Kron, Tomas; Rodrigues, George; Coad, Terry; Trenka, Kristina; Wong, Eugene; Bauman, Glenn; Dyk, Jake Van

2006-02-01

Lung cancer treatment can be one of the most challenging fields in radiotherapy. The aim of the present study was to compare different modalities of radiation delivery based on a balanced scoring scheme for target coverage and normal tissue avoidance. Treatment plans were developed for 15 patients with stage III inoperable non-small cell lung cancer using 3D conformal technique and intensity-modulated radiotherapy (IMRT). Elective nodal irradiation was included for all cases to create the most challenging scenarios with large target volumes. A 2 cm margin was used around the gross tumour volume (GTV) to generate PTV2 and 1cm margin around elective nodes for PTV1 resulting in PTV1 volumes larger than 1000 cm(3) in 13 of the 15 patients. 3D conformal and IMRT plans were generated on a commercial treatment planning system (TheraPlan Plus, Nucletron) with various combinations of beam energies and gantry angles. A 'dose quality factor' (DQF) was introduced to correlate the plan quality with patient specific parameters. A good correlation was found between the quality of the plans and the overlap between PTV1 and lungs. The patient feature factor (PFF), which is a product of several pertinent characteristics, was introduced to facilitate the choice of a particular technique for a particular patient. This approach may allow the evaluation of different treatment options prior to actual planning, subject to validation in larger prospective data sets.

Feasibility of using intensity-modulated radiotherapy to improve lung sparing in treatment planning for distal esophageal cancer.

PubMed

Chandra, Anurag; Guerrero, Thomas M; Liu, H Helen; Tucker, Susan L; Liao, Zhongxing; Wang, Xiaochun; Murshed, Hasan; Bonnen, Mark D; Garg, Amit K; Stevens, Craig W; Chang, Joe Y; Jeter, Melinda D; Mohan, Radhe; Cox, James D; Komaki, Ritsuko

2005-12-01

To evaluate the feasibility whether intensity-modulated radiotherapy (IMRT) can be used to reduce doses to normal lung than three-dimensional conformal radiotherapy (3 DCRT) in treating distal esophageal malignancies. Ten patient cases with cancer of the distal esophagus were selected for a retrospective treatment-planning study. IMRT plans using four, seven, and nine beams (4B, 7B, and 9B) were developed for each patient and compared with the 3 DCRT plan used clinically. IMRT and 3 DCRT plans were evaluated with respect to PTV coverage and dose-volumes to irradiated normal structures, with statistical comparison made between the two types of plans using the Wilcoxon matched-pair signed-rank test. IMRT plans (4B, 7B, 9B) reduced total lung volume treated above 10 Gy (V(10)), 20 Gy (V(20)), mean lung dose (MLD), biological effective volume (V(eff)), and lung integral dose (P<0.05). The median absolute improvement with IMRT over 3DCRT was approximately 10% for V(10), 5% for V(20), and 2.5 Gy for MLD. IMRT improved the PTV heterogeneity (P<0.05), yet conformity was better with 7B-9B IMRT plans. No clinically meaningful differences were observed with respect to the irradiated volumes of spinal cord, heart, liver, or total body integral doses. Dose-volume of exposed normal lung can be reduced with IMRT, though clinical investigations are warranted to assess IMRT treatment outcome of esophagus cancers.

Advantages and limitations of navigation-based multicriteria optimization (MCO) for localized prostate cancer IMRT planning

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

McGarry, Conor K., E-mail: conor.mcgarry@belfasttrust.hscni.net; Bokrantz, Rasmus; RaySearch Laboratories, Stockholm

2014-10-01

Efficacy of inverse planning is becoming increasingly important for advanced radiotherapy techniques. This study’s aims were to validate multicriteria optimization (MCO) in RayStation (v2.4, RaySearch Laboratories, Sweden) against standard intensity-modulated radiation therapy (IMRT) optimization in Oncentra (v4.1, Nucletron BV, the Netherlands) and characterize dose differences due to conversion of navigated MCO plans into deliverable multileaf collimator apertures. Step-and-shoot IMRT plans were created for 10 patients with localized prostate cancer using both standard optimization and MCO. Acceptable standard IMRT plans with minimal average rectal dose were chosen for comparison with deliverable MCO plans. The trade-off was, for the MCO plans, managedmore » through a user interface that permits continuous navigation between fluence-based plans. Navigated MCO plans were made deliverable at incremental steps along a trajectory between maximal target homogeneity and maximal rectal sparing. Dosimetric differences between navigated and deliverable MCO plans were also quantified. MCO plans, chosen as acceptable under navigated and deliverable conditions resulted in similar rectal sparing compared with standard optimization (33.7 ± 1.8 Gy vs 35.5 ± 4.2 Gy, p = 0.117). The dose differences between navigated and deliverable MCO plans increased as higher priority was placed on rectal avoidance. If the best possible deliverable MCO was chosen, a significant reduction in rectal dose was observed in comparison with standard optimization (30.6 ± 1.4 Gy vs 35.5 ± 4.2 Gy, p = 0.047). Improvements were, however, to some extent, at the expense of less conformal dose distributions, which resulted in significantly higher doses to the bladder for 2 of the 3 tolerance levels. In conclusion, similar IMRT plans can be created for patients with prostate cancer using MCO compared with standard optimization. Limitations exist within MCO regarding conversion of navigated plans to deliverable apertures, particularly for plans that emphasize avoidance of critical structures. Minimizing these differences would result in better quality treatments for patients with prostate cancer who were treated with radiotherapy using MCO plans.« less

Current external beam radiation therapy quality assurance guidance: does it meet the challenges of emerging image-guided technologies?

PubMed

Palta, Jatinder R; Liu, Chihray; Li, Jonathan G

2008-01-01

The traditional prescriptive quality assurance (QA) programs that attempt to ensure the safety and reliability of traditional external beam radiation therapy are limited in their applicability to such advanced radiation therapy techniques as three-dimensional conformal radiation therapy, intensity-modulated radiation therapy, inverse treatment planning, stereotactic radiosurgery/radiotherapy, and image-guided radiation therapy. The conventional QA paradigm, illustrated by the American Association of Physicists in Medicine Radiation Therapy Committee Task Group 40 (TG-40) report, consists of developing a consensus menu of tests and device performance specifications from a generic process model that is assumed to apply to all clinical applications of the device. The complexity, variation in practice patterns, and level of automation of high-technology radiotherapy renders this "one-size-fits-all" prescriptive QA paradigm ineffective or cost prohibitive if the high-probability error pathways of all possible clinical applications of the device are to be covered. The current approaches to developing comprehensive prescriptive QA protocols can be prohibitively time consuming and cost ineffective and may sometimes fail to adequately safeguard patients. It therefore is important to evaluate more formal error mitigation and process analysis methods of industrial engineering to more optimally focus available QA resources on process components that have a significant likelihood of compromising patient safety or treatment outcomes.

Restorative dentistry and oral rehabilitation: United Kingdom National Multidisciplinary Guidelines.

PubMed

Butterworth, C; McCaul, L; Barclay, C

2016-05-01

This is the official guideline endorsed by the specialty associations involved in the care of head and neck cancer patients in the UK and provides recommendations on the pre-treatment oral and dental assessment, during and after treatment and oral rehabilitation. Restorative dentists are core members of the multidisciplinary team treating head and neck cancer patients, involved from the treatment planning phase through to long-term rehabilitation. Recommendations • Preventative oral care must be delivered to patients whose cancer treatment will affect the oral cavity, jaws, salivary glands and oral accessibility. (G) • Close working and communication between the surgeons, oncologists and restorative dental specialists is important in ensuring optimal oral health outcomes. (G) • Intensity-modulated radiotherapy has been shown to reduce long-term xerostomia and should be offered to all appropriate patients. (R) • If patients are deemed at risk of trismus they should be warned and its progressive and potentially irreversible nature explained. (G) • Where it is known that adjuvant radiotherapy will be given, extractions should take place at primary surgery to maximise the time for healing and minimise the number of surgical events for patients. (G) • Osseointegrated implants should be considered for all patients having resection for head and neck cancer. (G).

Radiation techniques for esophageal cancer.

PubMed

Zhang, Minsi; Wu, Abraham J

2017-10-01

Radiotherapy plays a crucial role in the curative management of localized esophageal cancer, both as definitive and preoperative therapy. For definitive therapy, the standard radiation dose is 50.4 Gy in 28 fractions and should be delivered with concurrent chemotherapy. Chemoradiotherapy also has a wellestablished benefit in the preoperative setting, as established in the CROSS randomized trial. Radiation fields are typically generous, to account for subclinical extension of disease along the esophagus and to regional nodes. Three-dimensional conformal radiation is the current standard technique for esophageal cancer, though intensity-modulated radiation therapy is increasingly utilized and may improve the outcomes of esophageal radiotherapy by reducing radiation dose to critical normal tissues.

Automation of radiation treatment planning : Evaluation of head and neck cancer patient plans created by the Pinnacle3 scripting and Auto-Planning functions.

PubMed

Speer, Stefan; Klein, Andreas; Kober, Lukas; Weiss, Alexander; Yohannes, Indra; Bert, Christoph

2017-08-01

Intensity-modulated radiotherapy (IMRT) techniques are now standard practice. IMRT or volumetric-modulated arc therapy (VMAT) allow treatment of the tumor while simultaneously sparing organs at risk. Nevertheless, treatment plan quality still depends on the physicist's individual skills, experiences, and personal preferences. It would therefore be advantageous to automate the planning process. This possibility is offered by the Pinnacle 3 treatment planning system (Philips Healthcare, Hamburg, Germany) via its scripting language or Auto-Planning (AP) module. AP module results were compared to in-house scripts and manually optimized treatment plans for standard head and neck cancer plans. Multiple treatment parameters were scored to judge plan quality (100 points = optimum plan). Patients were initially planned manually by different physicists and re-planned using scripts or AP. Script-based head and neck plans achieved a mean of 67.0 points and were, on average, superior to manually created (59.1 points) and AP plans (62.3 points). Moreover, they are characterized by reproducibility and lower standard deviation of treatment parameters. Even less experienced staff are able to create at least a good starting point for further optimization in a short time. However, for particular plans, experienced planners perform even better than scripts or AP. Experienced-user input is needed when setting up scripts or AP templates for the first time. Moreover, some minor drawbacks exist, such as the increase of monitor units (+35.5% for scripted plans). On average, automatically created plans are superior to manually created treatment plans. For particular plans, experienced physicists were able to perform better than scripts or AP; thus, the benefit is greatest when time is short or staff inexperienced.

PRESAGE® as a solid 3-D radiation dosimeter: A review article

NASA Astrophysics Data System (ADS)

Khezerloo, Davood; Nedaie, Hassan Ali; Takavar, Abbas; Zirak, Alireza; Farhood, Bagher; Movahedinejhad, Hadi; Banaee, Nooshin; Ahmadalidokht, Isa; Knuap, Courtney

2017-12-01

Radiation oncology has been rapidly improved by the application of new equipment and techniques. With the advent of new complex and precise radiotherapy techniques such as intensity modulated radiotherapy, stereotactic radiosurgery, and volumetric modulated arc therapy, the demand for an accurate and feasible three-dimensional (3-D) dosimetry system has increased. The most important features of a 3-D dosimeter, apart from being precise, accurate and reproducible, include also its low cost, feasibility, and availability. In 2004 a new generation of solid plastic dosimeters which demonstrate a radiochromic response to ionizing radiation was introduced. PRESAGE® plastic dosimeter lacks the limitations of previous Ferric and polymer plastic 3-D dosimeters such as diffusion, sensitivity to oxygen, fabrication problems, scanning and read out challenges. In this decade, a large number of efforts have been carried out to enhance PRESAGE® structure and scanning methods. This article attempts to review and reflect on the results of these investigations.

Proton Radiotherapy for Pediatric Central Nervous System Germ Cell Tumors: Early Clinical Outcomes

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

MacDonald, Shannon M., E-mail: smacdonald@partners.or; Trofimov, Alexei; Safai, Sairos

Purpose: To report early clinical outcomes for children with central nervous system (CNS) germ cell tumors treated with protons; to compare dose distributions for intensity-modulated photon radiotherapy (IMRT), three-dimensional conformal proton radiation (3D-CPT), and intensity-modulated proton therapy with pencil beam scanning (IMPT) for whole-ventricular irradiation with and without an involved-field boost. Methods and Materials: All children with CNS germinoma or nongerminomatous germ cell tumor who received treatment at the Massachusetts General Hospital between 1998 and 2007 were included in this study. The IMRT, 3D-CPT, and IMPT plans were generated and compared for a representative case. Results: Twenty-two patients were treatedmore » with 3D-CPT. At a median follow-up of 28 months, there were no CNS recurrences; 1 patient had a recurrence outside the CNS. Local control, progression-free survival, and overall survival rates were 100%, 95%, and 100%, respectively. Comparable tumor volume coverage was achieved with IMRT, 3D-CPT, and IMPT. Substantial normal tissue sparing was seen with any form of proton therapy as compared with IMRT. The use of IMPT may yield additional sparing of the brain and temporal lobes. Conclusions: Preliminary disease control with proton therapy compares favorably to the literature. Dosimetric comparisons demonstrate the advantage of proton radiation over IMRT for whole-ventricle radiation. Superior dose distributions were accomplished with fewer beam angles utilizing 3D-CPT and scanned protons. Intensity-modulated proton therapy with pencil beam scanning may improve dose distribution as compared with 3D-CPT for this treatment.« less

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

Liang, Xiaodong, E-mail: lxdctopone@sina.com; Ni, Lingqin; Hu, Wei

The objective of this study was to evaluate the dose conformity and feasibility of whole-brain radiotherapy with a simultaneous integrated boost by forward intensity-modulated radiation therapy in patients with 1 to 3 brain metastases. Forward intensity-modulated radiation therapy plans were generated for 10 patients with 1 to 3 brain metastases on Pinnacle 6.2 Treatment Planning System. The prescribed dose was 30 Gy to the whole brain (planning target volume [PTV]{sub wbrt}) and 40 Gy to individual brain metastases (PTV{sub boost}) simultaneously, and both doses were given in 10 fractions. The maximum diameters of individual brain metastases ranged from 1.6 tomore » 6 cm, and the summated PTVs per patient ranged from 1.62 to 69.81 cm{sup 3}. Conformity and feasibility were evaluated regarding conformation number and treatment delivery time. One hundred percent volume of the PTV{sub boost} received at least 95% of the prescribed dose in all cases. The maximum doses were less than 110% of the prescribed dose to the PTV{sub boost}, and all of the hot spots were within the PTV{sub boost}. The volume of the PTV{sub wbrt} that received at least 95% of the prescribed dose ranged from 99.2% to 100%. The mean values of conformation number were 0.682. The mean treatment delivery time was 2.79 minutes. Ten beams were used on an average in these plans. Whole-brain radiotherapy with a simultaneous integrated boost by forward intensity-modulated radiation therapy in 1 to 3 brain metastases is feasible, and treatment delivery time is short.« less

Intensity-Modulated Radiation Therapy for the Treatment of Squamous Cell Anal Cancer With Para-aortic Nodal Involvement

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

Hodges, Joseph C.; Das, Prajnan, E-mail: PrajDas@mdanderson.or; Eng, Cathy

2009-11-01

Purpose: To determine the rates of toxicity, locoregional control, distant control, and survival in anal cancer patients with para-aortic nodal involvement, treated with intensity-modulated radiotherapy (IMRT) and concurrent chemotherapy at a single institution. Methods and Materials: Between 2001 and 2007, 6 patients with squamous cell anal cancer and para-aortic nodal involvement were treated with IMRT and concurrent infusional 5-fluorouracil and cisplatin. The primary tumor was treated with a median dose of 57.5 Gy (range, 54-60 Gy), involved para-aortic, pelvic, and inguinal lymph nodes were treated with a median dose of 55 Gy (range, 50.5-55 Gy), and noninvolved nodal regions weremore » treated with a median dose of 45 Gy (range, 43.5-45 Gy). Results: After a median follow-up of 25 months, none of the patients had a recurrence at the primary tumor, pelvic/inguinal nodes, or para-aortic nodes, whereas 2 patients developed distant metastases to the liver. Four of the 6 patients are alive. The 3-year actuarial locoregional control, distant control, and overall survival rates were 100%, 56%, and 63%, respectively. Four of the 6 patients developed Grade 3 acute gastrointestinal toxicity during chemoradiation. Conclusions: Intensity-modulated radiotherapy and concurrent chemotherapy could potentially serve as definitive therapy in anal cancer patients with para-aortic nodal involvement. Adjuvant chemotherapy may be indicated in these patients, as demonstrated by the distant failure rates. These patients need to be followed carefully because of the potential for treatment-related toxicities.« less

Protons and more: state of the art in radiotherapy.

PubMed

Hoskin, Peter J; Bhattacharya, Indrani S

2014-12-01

The purpose of modern radiotherapy is to deliver a precise high dose of radiation which will result in reproductive death of the cells. Radiation should transverse within the tumour volume whilst minimising damage to surrounding normal tissue. Overall 40% of cancers which are cured will have received radiotherapy. Current state of the art treatment will incorporate cross-sectional imaging and multiple high energy X-ray beams in processes called intensity modulated radiotherapy and image guided radiotherapy. Brachytherapy enables very high radiation doses to be delivered by the direct passage of a radiation source through or within the tumour volume and similar results can be achieved using rotational stereotactic X-ray beam techniques. Protons have the characteristics of particle beams which deposit their energy in a finite fixed peak at depth in tissue with no dose beyond this point - the Bragg peak. This has advantages in certain sites such as the spine adjacent to the spinal cord and particularly in children when the overall volume of tissue receiving radiation can be minimised. © 2014 Royal College of Physicians.

The role of PET in target localization for radiotherapy treatment planning.

PubMed

Rembielak, Agata; Price, Pat

2008-02-01

Positron emission tomography (PET) is currently accepted as an important tool in oncology, mostly for diagnosis, staging and restaging purposes. It provides a new type of information in radiotherapy, functional rather than anatomical. PET imaging can also be used for target volume definition in radiotherapy treatment planning. The need for very precise target volume delineation has arisen with the increasing use of sophisticated three-dimensional conformal radiotherapy techniques and intensity modulated radiation therapy. It is expected that better delineation of the target volume may lead to a significant reduction in the irradiated volume, thus lowering the risk of treatment complications (smaller safety margins). Better tumour visualisation also allows a higher dose of radiation to be applied to the tumour, which may lead to better tumour control. The aim of this article is to review the possible use of PET imaging in the radiotherapy of various cancers. We focus mainly on non-small cell lung cancer, lymphoma and oesophageal cancer, but also include current opinion on the use of PET-based planning in other tumours including brain, uterine cervix, rectum and prostate.

Influence of CT contrast agent on dose calculation of intensity modulated radiation therapy plan for nasopharyngeal carcinoma.

PubMed

Lee, F K-H; Chan, C C-L; Law, C-K

2009-02-01

Contrast enhanced computed tomography (CECT) has been used for delineation of treatment target in radiotherapy. The different Hounsfield unit due to the injected contrast agent may affect radiation dose calculation. We investigated this effect on intensity modulated radiotherapy (IMRT) of nasopharyngeal carcinoma (NPC). Dose distributions of 15 IMRT plans were recalculated on CECT. Dose statistics for organs at risk (OAR) and treatment targets were recorded for the plain CT-calculated and CECT-calculated plans. Statistical significance of the differences was evaluated. Correlations were also tested, among magnitude of calculated dose difference, tumor size and level of enhancement contrast. Differences in nodal mean/median dose were statistically significant, but small (approximately 0.15 Gy for a 66 Gy prescription). In the vicinity of the carotid arteries, the difference in calculated dose was also statistically significant, but only with a mean of approximately 0.2 Gy. We did not observe any significant correlation between the difference in the calculated dose and the tumor size or level of enhancement. The results implied that the calculated dose difference was clinically insignificant and may be acceptable for IMRT planning.

Swallowing performance and tube feeding status in patients treated with parotid-sparing intensity-modulated radiotherapy for head and neck cancer.

PubMed

Roe, Justin W G; Carding, Paul N; Drinnan, Michael J; Harrington, Kevin J; Nutting, Christopher M

2016-04-01

The purpose of this prospective study was to evaluate the swallowing performance of patients with head and neck cancer treated with parotid-sparing intensity-modulated radiotherapy (IMRT). Sixty-two patients were recruited. Data were collected before and up to 12 months after treatment. Measures included the Performance Status Scale for head and neck cancer (PSS-HN Normalcy of Diet and Eating in Public subscales), tube feeding status, and 100 mL water swallow test (WST) volume and capacity scores. There was a significant reduction in PSS-HN and WST scores from baseline to 3 months (p < .001). Significant improvements were observed up to 12 months on the PSS-HN. Swallowing volume and capacity scores recovered but did not reach statistical significance. Tube feeding was not required in 47% of the patients. IMRT significantly impacts on swallowing performance, although there is a trend for improvement up to 12 months after treatment. Our data support a case-by-case approach to tube feeding. © 2015 Wiley Periodicals, Inc. Head Neck 38: E1436-E1444, 2016. © 2015 Wiley Periodicals, Inc.

The challenge in treating locally recurrent T3-4 nasopharyngeal carcinoma: the survival benefit and severe late toxicities of re-irradiation with intensity-modulated radiotherapy.

PubMed

Tian, Yun-Ming; Huang, Wei-Zeng; Yuan, Xia; Bai, Li; Zhao, Chong; Han, Fei

2017-06-27

Effective treatments for patients with advanced locally recurrent nasopharyngeal carcinoma (NPC) are limited. This investigation was to determine the potential benefits from re-irradiation by intensity-modulated radiotherapy (IMRT) on survival and the effects of severe late toxicities. A retrospective study was conducted in 245 patients diagnosed with locally recurrent T3-T4 NPC who had undergone re-irradiation with IMRT. Follow-up data was colletedand factors associated with survival and severe late toxicities were analyzed. The 5-year local-regional failure-free survival, distant failure-free survival and overall survival rates were 60.9%, 78.3% and 27.5%, respectively. The presence of severe late complications, recurrent T4 disease and gross tumor volume >30 cm3 were associated with poor survival. The incidences of mucosal necrosis, temporal lobe necrosis, cranial neuropathy and trismus were 22.0%, 14.6%, 27.0% and 14.6% respectively. Re-irradiation with IMRT is an effective choice in patients with locally recurrent T3-T4 NPC. However, the survival benefits can be partly offset by severe late complications and optimum treatments in these patients remain a challenge.

Dosimetric quality, accuracy, and deliverability of modulated radiotherapy treatments for spinal metastases

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

Kairn, Tanya, E-mail: t.kairn@gmail.com; School of Chemistry, Physics, and Mechanical Engineering, Queensland University of Technology, Brisbane; Papworth, Daniel

2016-10-01

Cancer often metastasizes to the vertebra, and such metastases can be treated successfully using simple, static posterior or opposed-pair radiation fields. However, in some cases, including when re-irradiation is required, spinal cord avoidance becomes necessary and more complex treatment plans must be used. This study evaluated 16 sample intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT) treatment plans designed to treat 6 typical vertebral and paraspinal volumes using a standard prescription, with the aim of investigating the advantages and limitations of these treatment techniques and providing recommendations for their optimal use in vertebral treatments. Treatment plan quality and beammore » complexity metrics were evaluated using the Treatment And Dose Assessor (TADA) code. A portal-imaging–based quality assurance (QA) system was used to evaluate treatment delivery accuracy, and radiochromic film measurements were used to provide high-resolution verification of treatment plan dose accuracy, especially in the steep dose gradient regions between each vertebral target and spinal cord. All treatment modalities delivered approximately the same doses and the same levels of dose heterogeneity to each planning target volume (PTV), although the minimum PTV doses in the vertebral plans were substantially lower than the prescription, because of the requirement that the plans meet a strict constraint on the dose to the spinal cord and cord planning risk volume (PRV). All plans met required dose constraints on all organs at risk, and all measured PTV-cord dose gradients were steeper than planned. Beam complexity analysis suggested that the IMRT treatment plans were more deliverable (less complex, leading to greater QA success) than the VMAT treatment plans, although the IMRT plans also took more time to deliver. The accuracy and deliverability of VMAT treatment plans were found to be substantially increased by limiting the number of monitor units (MU) per beam at the optimization stage, and thereby limiting beam modulation complexity. The VMAT arcs that were optimized with MU limitation had higher QA pass rates as well as higher modulation complexity scores (less complexity), lower modulation indices (less modulation), lower MU per beam, larger beam segments, and fewer small apertures than the VMAT arcs that were optimized without MU limitation. It is recommended that VMAT treatments for vertebral volumes, where the PTV abuts or surrounds the spinal cord, should be optimized with MU limitation. IMRT treatments may be preferable to the VMAT treatments, for dosimetry and deliverability reasons, but may be inappropriate for some patients because of their increased treatment delivery time.« less

Audits for advanced treatment dosimetry

NASA Astrophysics Data System (ADS)

Ibbott, G. S.; Thwaites, D. I.

2015-01-01

Radiation therapy has advanced rapidly over the last few decades, progressing from 3D conformal treatment to image-guided intensity modulated therapy of several different flavors, both 3D and 4D and to adaptive radiotherapy. The use of intensity modulation has increased the complexity of quality assurance and essentially eliminated the physicist's ability to judge the validity of a treatment plan, even approximately, on the basis of appearance and experience. Instead, complex QA devices and procedures are required at the institutional level. Similarly, the assessment of treatment quality through remote and on-site audits also requires greater sophistication. The introduction of 3D and 4D dosimetry into external audit systems must follow, to enable quality assurance systems to perform meaningful and thorough audits.

Risk-adaptive radiotherapy

NASA Astrophysics Data System (ADS)

Kim, Yusung

Currently, there is great interest in integrating biological information into intensity-modulated radiotherapy (IMRT) treatment planning with the aim of boosting high-risk tumor subvolumes. Selective boosting of tumor subvolumes can be accomplished without violating normal tissue complication constraints using information from functional imaging. In this work we have developed a risk-adaptive optimization-framework that utilizes a nonlinear biological objective function. Employing risk-adaptive radiotherapy for prostate cancer, it is possible to increase the equivalent uniform dose (EUD) by up to 35.4 Gy in tumor subvolumes having the highest risk classification without increasing normal tissue complications. Subsequently, we have studied the impact of functional imaging accuracy, and found on the one hand that loss in sensitivity had a large impact on expected local tumor control, which was maximal when a low-risk classification for the remaining low risk PTV was chosen. While on the other hand loss in specificity appeared to have a minimal impact on normal tissue sparing. Therefore, it appears that in order to improve the therapeutic ratio a functional imaging technique with a high sensitivity, rather than specificity, is needed. Last but not least a comparison study between selective boosting IMRT strategies and uniform-boosting IMRT strategies yielding the same EUD to the overall PTV was carried out, and found that selective boosting IMRT considerably improves expected TCP compared to uniform-boosting IMRT, especially when lack of control of the high-risk tumor subvolumes is the cause of expected therapy failure. Furthermore, while selective boosting IMRT, using physical dose-volume objectives, did yield similar rectal and bladder sparing when compared its equivalent uniform-boosting IMRT plan, risk-adaptive radiotherapy, utilizing biological objective functions, did yield a 5.3% reduction in NTCP for the rectum. Hence, in risk-adaptive radiotherapy the therapeutic ratio can be increased over that which can be achieved with conventional selective boosting IMRT using physical dose-volume objectives. In conclusion, a novel risk-adaptive radiotherapy strategy is proposed and promises increased expected local control for locoregionally advanced tumors with equivalent or better normal tissue sparing.

Anal Cancer: An Examination of Radiotherapy Strategies

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

Glynne-Jones, Rob; Lim, Faye

2011-04-01

The Radiation Therapy Oncology Group 9811, ACCORD-03, and ACT II Phase III trials in anal cancer showed no benefit for cisplatin-based induction and maintenance chemotherapy, or radiation dose-escalation >59 Gy. This review examines the efficacy and toxicity of chemoradiation (CRT) in anal cancer, and discusses potential alternative radiotherapy strategies. The evidence for the review was compiled from randomized and nonrandomized trials of radiation therapy and CRT. A total of 103 retrospective/observational studies, 4 Phase I/II studies, 16 Phase II prospective studies, 2 randomized Phase II studies, and 6 Phase III trials of radiotherapy or chemoradiation were identified. There are nomore » meta-analyses based on individual patient data. A 'one-size-fits-all' approach for all stages of anal cancer is inappropriate. Early T1 tumors are probably currently overtreated, whereas T3/T4 lesions might merit escalation of treatment. Intensity-modulated radiotherapy or the integration of biological therapy may play a role in future.« less

How to identify rectal sub-regions likely involved in rectal bleeding in prostate cancer radiotherapy

NASA Astrophysics Data System (ADS)

Dréan, G.; Acosta, O.; Ospina, J. D.; Voisin, C.; Rigaud, B.; Simon, A.; Haigron, P.; de Crevoisier, R.

2013-11-01

Nowadays, the de nition of patient-speci c constraints in prostate cancer radiotherapy planning are solely based on dose-volume histogram (DVH) parameters. Nevertheless those DVH models lack of spatial accuracy since they do not use the complete 3D information of the dose distribution. The goal of the study was to propose an automatic work ow to de ne patient-speci c rectal sub-regions (RSR) involved in rectal bleeding (RB) in case of prostate cancer radiotherapy. A multi-atlas database spanning the large rectal shape variability was built from a population of 116 individuals. Non-rigid registration followed by voxel-wise statistical analysis on those templates allowed nding RSR likely correlated with RB (from a learning cohort of 63 patients). To de ne patient-speci c RSR, weighted atlas-based segmentation with a vote was then applied to 30 test patients. Results show the potentiality of the method to be used for patient-speci c planning of intensity modulated radiotherapy (IMRT).

Implementation of a software for REmote COMparison of PARticlE and photon treatment plans: ReCompare.

PubMed

Löck, Steffen; Roth, Klaus; Skripcak, Tomas; Worbs, Mario; Helmbrecht, Stephan; Jakobi, Annika; Just, Uwe; Krause, Mechthild; Baumann, Michael; Enghardt, Wolfgang; Lühr, Armin

2015-09-01

To guarantee equal access to optimal radiotherapy, a concept of patient assignment to photon or particle radiotherapy using remote treatment plan exchange and comparison - ReCompare - was proposed. We demonstrate the implementation of this concept and present its clinical applicability. The ReCompare concept was implemented using a client-server based software solution. A clinical workflow for the remote treatment plan exchange and comparison was defined. The steps required by the user and performed by the software for a complete plan transfer were described and an additional module for dose-response modeling was added. The ReCompare software was successfully tested in cooperation with three external partner clinics and worked meeting all required specifications. It was compatible with several standard treatment planning systems, ensured patient data protection, and integrated in the clinical workflow. The ReCompare software can be applied to support non-particle radiotherapy institutions with the patient-specific treatment decision on the optimal irradiation modality by remote treatment plan exchange and comparison. Copyright © 2015. Published by Elsevier GmbH.

IMRT treatment of anal cancer with a scrotal shield

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

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

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

Optimization, Characterization and Commissioning of a Novel Uniform Scanning Proton Beam Delivery System

NASA Astrophysics Data System (ADS)

Mascia, Anthony Edward

Purpose: To develop and characterize the required detectors for uniform scanning optimization and characterization, and to develop the methodology and assess their efficacy for optimizing, characterizing and commissioning a novel proton beam uniform scanning system. Methods and Materials: The Multi Layer Ion Chamber (MLIC), a 1D array of vented parallel plate ion chambers, was developed in-house for measurement of longitudinal profiles. The Matrixx detector (IBA Dosimetry, Germany) and XOmat V film (Kodak, USA) were characterized for measurement of transverse profiles. The architecture of the uniform scanning system was developed and then optimized and characterized for clinical proton radiotherapy. Results: The MLIC detector significantly increased data collection efficiency without sacrificing data quality. The MLIC was capable of integrating an entire scanned and layer stacked proton field with one measurement, producing results with the equivalent spatial sampling of 1.0mm. The Matrixx detector and modified 1D water phantom jig improved data acquisition efficiency and complemented the film measurements. The proximal, central and distal proton field planes were measured using these methods, yielding better than 3% uniformity. The binary range modulator was programmed, optimized and characterized such that the proton field ranges were separated by approximately 5.0mm modulation width and delivered with an accuracy of 1.0mm in water. Several wobbling magnet scan patterns were evaluated and the raster pattern, spot spacing, scan amplitude and overscan margin were optimized for clinical use. Conclusion: Novel detectors and methods are required for clinically efficient optimization and characterization of proton beam scanning systems. Uniform scanning produces proton beam fields that are suited for clinical proton radiotherapy.

Dynamic 3D measurement of modulated radiotherapy: a scintillator-based approach

NASA Astrophysics Data System (ADS)

Archambault, Louis; Rilling, Madison; Roy-Pomerleau, Xavier; Thibault, Simon

2017-05-01

With the rise of high-conformity dynamic radiotherapy, such as volumetric modulated arc therapy and robotic radiosurgery, the temporal dimension of dose measurement is becoming increasingly important. It must be possible to tell both ‘where’ and ‘when’ a discrepancy occurs between the plan and its delivery. A 3D scintillation-based dosimetry system could be ideal for such a thorough, end-to-end verification; however, the challenge lies in retrieving the volumetric information of the light-emitting volume. This paper discusses the motivation, from an optics point of view, of using the images acquired with a plenoptic camera, or light field imager, of an irradiated plastic scintillator volume to reconstruct the delivered 3D dose distribution. Current work focuses on the optimization of the optical design as well as the data processing that is involved in the ongoing development of a clinically viable, second generation dosimetry system.

Dosimetric impact of a change in breathing period on VMAT stereotactic ablative body radiotherapy

NASA Astrophysics Data System (ADS)

Olding, T.; Alexander, KM

2017-05-01

The dosimetric impact of a change in breathing period during treatment was assessed for a volumetric modulated arc therapy (VMAT) stereotactic ablative radiotherapy (SABR) lung plan optimized according to our centre’s planning protocol. Plan delivery was evaluated at three breathing rates ranging from 7 to 23 breaths-per-minute (BPM) against the planning anatomy (15 BPM) calculated dose. Dynamic ion chamber, EBT3 film and Fricke-xylenol orange-gelatin (FXG) gel measurements were acquired using a motion phantom with appropriate inserts for each dosimeter. The results show good agreement between measured and calculated plan dose within the internal gross tumour volume (IGTV) target.

SU-E-T-618: Dosimetric Comparison of Manual and Beam Angle Optimization of Gantry Angles in IMRT for Cervical Cancer

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

Lin, X; Sun, T; Liu, T

2014-06-01

Purpose: To evaluate the dosimetric characteristics of intensity-modulated radiotherapy (IMRT) treatment plan with beam angle optimization. Methods: Ten post-operation patients with cervical cancer were included in this analysis. Two IMRT plans using seven beams were designed in each patient. A standard coplanar equi-space beam angles were used in the first plan (plan 1), whereas the selection of beam angle was optimized by beam angle optimization algorithm in Varian Eclipse treatment planning system for the same number of beams in the second plan (plan 2). Two plans were designed for each patient with the same dose-volume constraints and prescription dose. Allmore » plans were normalized to the mean dose to PTV. The dose distribution in the target, the dose to the organs at risk and total MU were compared. Results: For conformity and homogeneity in PTV, no statistically differences were observed in the two plans. For the mean dose in bladder, plan 2 were significantly lower than plan 1(p<0.05). No statistically significant differences were observed between two plans for the mean doses in rectum, left and right femur heads. Compared with plan1, the average monitor units reduced 16% in plan 2. Conclusion: The IMRT plan based on beam angle optimization for cervical cancer could reduce the dose delivered to bladder and also reduce MU. Therefore there were some dosimetric advantages in the IMRT plan with beam angle optimization for cervical cancer.« less

Evaluation of surface and shallow depth dose reductions using a Superflab bolus during conventional and advanced external beam radiotherapy.

PubMed

Yoon, Jihyung; Xie, Yibo; Zhang, Rui

2018-03-01

The purpose of this study was to evaluate a methodology to reduce scatter and leakage radiations to patients' surface and shallow depths during conventional and advanced external beam radiotherapy. Superflab boluses of different thicknesses were placed on top of a stack of solid water phantoms, and the bolus effect on surface and shallow depth doses for both open and intensity-modulated radiotherapy (IMRT) beams was evaluated using thermoluminescent dosimeters and ion chamber measurements. Contralateral breast dose reduction caused by the bolus was evaluated by delivering clinical postmastectomy radiotherapy (PMRT) plans to an anthropomorphic phantom. For the solid water phantom measurements, surface dose reduction caused by the Superflab bolus was achieved only in out-of-field area and on the incident side of the beam, and the dose reduction increased with bolus thickness. The dose reduction caused by the bolus was more significant at closer distances from the beam. Most of the dose reductions occurred in the first 2-cm depth and stopped at 4-cm depth. For clinical PMRT treatment plans, surface dose reductions using a 1-cm Superflab bolus were up to 31% and 62% for volumetric-modulated arc therapy and 4-field IMRT, respectively, but there was no dose reduction for Tomotherapy. A Superflab bolus can be used to reduce surface and shallow depth doses during external beam radiotherapy when it is placed out of the beam and on the incident side of the beam. Although we only validated this dose reduction strategy for PMRT treatments, it is applicable to any external beam radiotherapy and can potentially reduce patients' risk of developing radiation-induced side effects. © 2018 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.

Adaptive radiotherapy for head and neck cancers: Fact or fallacy to improve therapeutic ratio?

PubMed

Li, Y Q; Tan, J S H; Wee, J T S; Chua, M L K

2018-04-23

Modern standards of precision radiotherapy, primarily driven by the technological advances of intensity modulation and image guidance, have led to increased versatility in radiotherapy planning and delivery. The ability to shape doses around critical normal organs, while simultaneously "painting" boost doses to the tumor have translated to substantial therapeutic gains in head and neck cancer patients. Recently, dose adaptation (or adaptive radiotherapy) has been proposed as a novel concept to enhance the therapeutic ratio of head and neck radiotherapy, facilitated in part by the onset of molecular and functional imaging. These contemporary imaging techniques have enabled visualisation of the spatial molecular architecture of the tumor. Daily cone-beam imaging, besides improving treatment accuracy, offers another unique angle to explore radiomics - a novel high throughput feature extraction and selection workflow, for adapting radiotherapy based on real-time tumor changes. Here, we review the existing evidence of molecular and functional imaging in head and neck cancers, as well as the current application of adaptive radiotherapy in the treatment of this tumor type. We propose that adaptive radiotherapy can be further exploited through a systematic application of molecular and functional imaging, including radiomics, at the different phases of planning and treatment. Copyright © 2018 Société française de radiothérapie oncologique (SFRO). Published by Elsevier SAS. All rights reserved.

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

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

Peterson, Jennifer L., E-mail: peterson.jennifer2@mayo.edu; Buskirk, Steven J.; Heckman, Michael G.

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 Terminologymore » 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.« less

Reirradiation for recurrent head and neck cancers using charged particle or photon radiotherapy.

PubMed

Yamazaki, Hideya; Demizu, Yusuke; Okimoto, Tomoaki; Ogita, Mikio; Himei, Kengo; Nakamura, Satoaki; Suzuki, Gen; Yoshida, Ken; Kotsuma, Tadayuki; Yoshioka, Yasuo; Oh, Ryoongjin

2017-07-01

To examine the outcomes of reirradiation for recurrent head and neck cancers using different modalities. This retrospective study included 26 patients who received charged particle radiotherapy (CP) and 150 who received photon radiotherapy (117 CyberKnife radiotherapy [CK] and 36 intensity-modulated radiotherapy [IMRT]). Inverse probability of treatment weighting (IPTW) involving propensity scores was used to reduce background selection bias. Higher prescribed doses were used in CP than photon radiotherapy. The 1‑year overall survival (OS) rates were 67.9% for CP and 54.1% for photon radiotherapy (p = 0.15; 55% for CK and 51% for IMRT). In multivariate Cox regression, the significant prognostic factors for better survival were nasopharyngeal cancer, higher prescribed dose, and lower tumor volume. IPTW showed a statistically significant difference between CP and photon radiotherapy (p = 0.04). The local control rates for patients treated with CP and photon radiotherapy at 1 year were 66.9% (range 46.3-87.5%) and 67.1% (range 58.3-75.9%), respectively. A total of 48 patients (27%) experienced toxicity grade ≥3 (24% in the photon radiotherapy group and 46% in the CP group), including 17 patients with grade 5 toxicity. Multivariate analysis revealed that younger age and a larger planning target volume (PTV) were significant risk factors for grade 3 or worse toxicity. CP provided superior survival outcome compared to photon radiotherapy. Tumor volume, primary site (nasopharyngeal), and prescribed dose were identified as survival factors. Younger patients with a larger PTV experienced toxicity grade ≥3.

Technical and clinical description of a case of extensive anogenital Paget's disease associated with anal cancer treated by tomotherapy.

PubMed

Garibaldi, Elisabetta; Cattari, Gabriella; Delmastro, Elena; Siatis, Dimitrios; Racca, Manuela; Maggio, Angelo; Gabriele, Domenico; Frangipane, Elena; Gabriele, Pietro

2014-01-01

In this paper we describe a case of extramammary Paget's disease associated with anal cancer, which was successfully treated by intensity-modulated radiotherapy using tomotherapy with a simultaneous integrated boost and daily image guidance. The main pitfall in this report is the relatively short follow-up (1 year), which means that the evaluated data is promising but not conclusive. Considering the rarity and wide extension of our patient's Paget's disease in the anogenital region, and the lack of literature reports about curative radiotherapy in this particular setting, this case report may be considered the first related to extensive extramammary Paget's disease treated by tomotherapy.

Radiotherapy Dose-Volume Effects on Salivary Gland Function

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

Deasy, Joseph O., E-mail: jdeasy@radonc.wustl.ed; Moiseenko, Vitali; Marks, Lawrence

2010-03-01

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

[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. Copyright © 2013. Published by Elsevier SAS.

Female pelvic synthetic CT generation based on joint intensity and shape analysis

NASA Astrophysics Data System (ADS)

Liu, Lianli; Jolly, Shruti; Cao, Yue; Vineberg, Karen; Fessler, Jeffrey A.; Balter, James M.

2017-04-01

Using MRI for radiotherapy treatment planning and image guidance is appealing as it provides superior soft tissue information over CT scans and avoids possible systematic errors introduced by aligning MR to CT images. This study presents a method that generates Synthetic CT (MRCT) volumes by performing probabilistic tissue classification of voxels from MRI data using a single imaging sequence (T1 Dixon). The intensity overlap between different tissues on MR images, a major challenge for voxel-based MRCT generation methods, is addressed by adding bone shape information to an intensity-based classification scheme. A simple pelvic bone shape model, built from principal component analysis of pelvis shape from 30 CT image volumes, is fitted to the MR volumes. The shape model generates a rough bone mask that excludes air and covers bone along with some surrounding soft tissues. Air regions are identified and masked out from the tissue classification process by intensity thresholding outside the bone mask. A regularization term is added to the fuzzy c-means classification scheme that constrains voxels outside the bone mask from being assigned memberships in the bone class. MRCT image volumes are generated by multiplying the probability of each voxel being represented in each class with assigned attenuation values of the corresponding class and summing the result across all classes. The MRCT images presented intensity distributions similar to CT images with a mean absolute error of 13.7 HU for muscle, 15.9 HU for fat, 49.1 HU for intra-pelvic soft tissues, 129.1 HU for marrow and 274.4 HU for bony tissues across 9 patients. Volumetric modulated arc therapy (VMAT) plans were optimized using MRCT-derived electron densities, and doses were recalculated using corresponding CT-derived density grids. Dose differences to planning target volumes were small with mean/standard deviation of 0.21/0.42 Gy for D0.5cc and 0.29/0.33 Gy for D99%. The results demonstrate the accuracy of the method and its potential in supporting MRI only radiotherapy treatment planning.

Dosimetric comparison of photon and proton treatment techniques for chondrosarcoma of thoracic spine

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

Yadav, Poonam, E-mail: yadav@humonc.wisc.edu; Department of Medical Physics, University of Wisconsin, Madison, WI; University of Wisconsin Riverview Cancer Center, Wisconsin Rapids, WI

2013-10-01

Chondrosarcomas are relatively radiotherapy resistant, and also delivering high radiation doses is not feasible owing to anatomic constraints. In this study, the feasibility of helical tomotherapy for treatment of chondrosarcoma of thoracic spine is explored and compared with other available photon and proton radiotherapy techniques in the clinical setting. A patient was treated for high-grade chondrosarcoma of the thoracic spine using tomotherapy. Retrospectively, the tomotherapy plan was compared with intensity-modulated radiation therapy, dynamic arc photon therapy, and proton therapy. Two primary comparisons were made: (1) comparison of normal tissue sparing with comparable target volume coverage (plan-1), and (2) comparison ofmore » target volume coverage with a constrained maximum dose to the cord center (plan-2). With constrained target volume coverage, proton plans were found to yield lower mean doses for all organs at risk (spinal cord, esophagus, heart, and both lungs). Tomotherapy planning resulted in the lowest mean dose to all organs at risk amongst photon-based methods. For cord dose constrained plans, the static-field intensity-modulated radiation therapy and dynamic arc plans resulted target underdosing in 20% and 12% of planning target volume2 volumes, respectively, whereas both proton and tomotherapy plans provided clinically acceptable target volume coverage with no portion of planning target volume2 receiving less than 90% of the prescribed dose. Tomotherapy plans are comparable to proton plans and produce superior results compared with other photon modalities. This feasibility study suggests that tomotherapy is an attractive alternative to proton radiotherapy for delivering high doses to lesions in the thoracic spine.« less

Prone breast forward intensity-modulated radiotherapy for Asian women with early left breast cancer: factors for cardiac sparing and clinical outcomes

PubMed Central

Chen, Jenny Ling-Yu; Cheng, Jason Chia-Hsien; Kuo, Sung-Hsin; Chan, Hsing-Min; Huang, Yu-Sen; Chen, Yu-Hsuan

2013-01-01

Since December 2009, after breast-conserving surgery for Stage 0–I cancer of the left breast, 21 women with relatively pendulous breasts underwent computed tomography prone and supine simulations. The adjuvant radiotherapy was 50 Gy in 25 fractions to the left breast alone. Four plans—conventional wedged tangents and forward intensity-modulated radiotherapy (fIMRT) in supine and prone positions—were generated. fIMRT generated better homogeneity in both positions. Prone position centralized the breast tissue by gravity and also shortened the breast width which led to better conformity in both planning techniques. Prone fIMRT significantly reduced doses to left lung, Level I and Level II axilla. The mean cardiac doses did not differ between positions. Among the four plans, prone fIMRT produced the best target dosimetry and normal organ sparing. In subgroup analysis, patients with absolute breast depth > 7 cm in the prone position or breast depth difference > 3 cm between positions had significant cardiac sparing with prone fIMRT. Sixteen patients with significant cardiac sparing in prone position were treated using prone fIMRT and the others using supine fIMRT. All patients received a supine electron tumor bed boost of 10 Gy in 5 fractions. No patients developed Grade 2 or worse acute or late toxicities. There was no difference in the number of segments or beams, monitor units, treatment time, or positioning reproducibility between prone and supine positions. At a median follow-up time of 26.8 months, no locoregional or distant recurrence or death was noted. PMID:23504450

Survey of the Patterns of Using Stereotactic Ablative Radiotherapy for Early-Stage Non-small Cell Lung Cancer in Korea.

PubMed

Song, Sanghyuk; Chang, Ji Hyun; Kim, Hak Jae; Kim, Yeon Sil; Kim, Jin Hee; Ahn, Yong Chan; Kim, Jae-Sung; Song, Si Yeol; Moon, Sung Ho; Cho, Moon June; Youn, Seon Min

2017-07-01

Stereotactic ablative radiotherapy (SABR) is an effective emerging technique for early-stage non-small cell lung cancer (NSCLC). We investigated the current practice of SABR for early-stage NSCLC in Korea. We conducted a nationwide survey of SABR for NSCLC by sending e-mails to all board-certified members of the Korean Society for Radiation Oncology. The survey included 23 questions focusing on the technical aspects of SABR and 18 questions seeking the participants' opinions on specific clinical scenarios in the use of SABR for early-stage NSCLC. Overall, 79 radiation oncologists at 61/85 specialist hospitals in Korea (71.8%) responded to the survey. SABR was used at 33 institutions (54%) to treat NSCLC. Regarding technical aspects, the most common planning methods were the rotational intensity-modulated technique (59%) and the static intensity-modulated technique (49%). Respiratory motion was managed by gating (54%) or abdominal compression (51%), and 86% of the planning scans were obtained using 4-dimensional computed tomography. In the clinical scenarios, the most commonly chosen fractionation schedule for peripherally located T1 NSCLC was 60 Gy in four fractions. For centrally located tumors and T2 NSCLC, the oncologists tended to avoid SABR for radiotherapy, and extended the fractionation schedule. The results of our survey indicated that SABR is increasingly being used to treat NSCLC in Korea. However, there were wide variations in the technical protocols and fractionation schedules of SABR for early-stage NSCLC among institutions. Standardization of SABR is necessary before implementing nationwide, multicenter, randomized studies.

Recurrence in Region of Spared Parotid Gland After Definitive Intensity-Modulated Radiotherapy for Head and Neck Cancer

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

Cannon, Donald M.; Lee, Nancy Y.

2008-03-01

Purpose: To discuss the implications of three examples of periparotid recurrence after definitive intensity-modulated radiotherapy (IMRT) for head and neck cancer (HNC). Methods and Materials: We present 3 patients with HNC who underwent definitive IMRT with concurrent chemotherapy and later had treatment failure in or near a spared parotid gland. Two patients had bilateral multilevel nodal disease, and all had Level II nodal disease ipsilateral to the site of recurrence. The patients were treated using dose-painting IMRT with a dose of 70 Gy to the gross tumor volume and 59.4 Gy or 54 Gy to the high-risk or low-risk clinicalmore » tumor volume, respectively. The parotid glands were spared bilaterally. The patients had not undergone any surgical treatment for HNC before radiotherapy. Results: All patients had treatment failure in the region of a spared parotid gland. Failure in the 2 patients with bilateral multilevel nodal involvement occurred in the periparotid lymph nodes. The third patient developed a dermal metastasis near the tail of a spared parotid gland. On pretreatment imaging, the 2 patients with nodal failure had small nonspecific periparotid nodules that showed no hypermetabolic activity on positron emission tomography. Conclusion: For HNC patients receiving definitive IMRT, nonspecific positron emission tomography-negative periparotid nodules on pretreatment imaging should raise the index of suspicion for subclinical disease in the presence of multilevel or Level II nodal metastases. Additional evaluation of such nodules might be indicated before sparing the ipsilateral parotid gland.« less

Definitive intensity-modulated radiotherapy concurrent with systemic therapy for oropharyngeal squamous cell carcinoma: Outcomes from an integrated regional Australian cancer centre.

PubMed

Masoud Rahbari, Reza; Winkley, Lauren; Hill, Jacques; Tahir, Abdul Rahim Mohammed; McKay, Michael; Last, Andrew; Shakespeare, Thomas P; Dwyer, Patrick

2016-06-01

Oropharyngeal squamous cell carcinoma (OPSCC) incidence has increased over the past two decades largely because of an increase in human papilloma virus (HPV)-related OPSCC. We report here outcomes of definitive radiation therapy for OPSCC with simultaneous integrated boost intensity-modulated radiotherapy (IMRT) in a regional Australian cancer centre. We retrospectively reviewed electronic medical records (EMR) of all patients treated with IMRT for head and neck cancer. We included patients who received a curative intent IMRT for OPSCC (2010-2014). Of 61 patients, 80% were men, and the median age was 57 years. Ninety percent of our patients received concurrent systemic therapy, and 68% were p16 positive. The median radiotherapy dose received was 70 Gy in 35 fractions. The median follow up for surviving patients was 22 months. Twenty-four month actuarial data show that the loco-regional recurrence free, metastasis-free MFS, cancer-specific (CaSS) and overall survival percentages were 98.3%, 92.6%, 91% and 90.3%, respectively. We did not observe grades 4 or 5 acute or late toxicities, and 10 patients (16.2%) exhibited persistent grade 3 toxicity 6 months after completing the treatment. The results from curative IMRTs for OPSCC delivered in a regional cancer centre are comparable with results published by tertiary referral centres. A long-term follow up of this patient cohort will continue for further analyses and comparisons with tertiary centres. © 2016 The Royal Australian and New Zealand College of Radiologists.

Can a peri-rectal hydrogel spaceOAR programme for prostate cancer intensity-modulated radiotherapy be successfully implemented in a regional setting?

PubMed

Te Velde, Bridget L; Westhuyzen, Justin; Awad, Nader; Wood, Maree; Shakespeare, Thomas P

2017-08-01

The aim of this study was to investigate whether the implementation of a hydrogel spacer (SpaceOAR) programme for patients treated with 81 Gy prostate intensity-modulated radiotherapy (IMRT) in a regional setting can reduce rectal doses and toxicity. In this retrospective study, 125 patients with localised prostate cancer treated between April 2014 (programme commencement) and June 2015 were compared: 65 with SpaceOAR (inserted by five different urologists) and 60 patients treated over the same time period without SpaceOAR. Patients were treated with 81 Gy in 45Fx of IMRT over 9 weeks. Planning aims included restricting rectal doses to V40 Gy < 35%, V65 Gy < 17%, V75 Gy < 10%. Acute toxicity was assessed weekly during radiotherapy and at 12 weeks. Rectal volume parameters were all significantly lower in the SpaceOAR group, with an associated reduction in acute diarrhoea (13.8% vs 31.7%). There were no significant differences in the very low rates of acute and late faecal incontinence or proctitis, however, there was a trend towards increased haemorrhoid rate in the SpaceOAR group (11.7% vs 3.1%, P = 0.09). A SpaceOAR programme in a regional setting with urologists performing low volumes of insertions (<1 per month on average) is of clinical benefit, and was associated with significantly lower radiation doses to the rectum and lower rates of acute diarrhoea. © 2017 The Royal Australian and New Zealand College of Radiologists.

Poster - 31: Predicting IQ and hearing loss following radiotherapy in pediatric brain tumors: proton vs photon

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

Fortin, Dominique; Ng, Angela; Tsang, Derek

Purpose: The increased sparing of normal tissues in intensity modulated proton therapy (IMPT) in pediatric brain tumor treatments should translate into improved neurocognitive outcomes. Models were used to estimate the intelligence quotient (IQ) and the risk of hearing loss 5 years post radiotherapy and to compare outcomes of proton against photon in pediatric brain tumors. Methods: Patients who had received intensity modulated radiotherapy (IMRT) were randomly selected from our retrospective database. The existing planning CT and contours were used to generate IMPT plans. The RBE-corrected dose was calculated for both IMPT and IMRT. For each patient, the IQ was estimatedmore » via a Monte Carlo technique, whereas the reported incidence of hearing loss as a function of cochlear dose was used to estimate the probability of occurrence. Results: The integrated brain dose was reduced in all IMPT plans, translating into a gain of 2 IQ points on average for protons for the whole cohort at 5 years post-treatment. In terms of specific diseases, the gains in IQ ranged from 0.8 points for medulloblastoma, to 2.7 points for craniopharyngioma. Hearing loss probability was evaluated on a per-ear-basis and was found to be systematically less for proton versus photon: overall 2.9% versus 7.2%. Conclusions: A method was developed to predict IQ and hearing outcomes in pediatric brain tumor patients on a case-by-case basis. A modest gain was systematically observed for proton in all patients. Given the uncertainties within the model used and our reinterpretation, these gains may be underestimated.« less

Prospective study of neoadjuvant chemoradiotherapy using intensity-modulated radiotherapy and 5 fluorouracil for locally advanced rectal cancer - toxicities and response assessment.

PubMed

Simson, David K; Mitra, Swarupa; Ahlawat, Parveen; Saxena, Upasna; Sharma, Manoj Kumar; Rawat, Sheh; Singh, Harpreet; Bansal, Babita; Sripathi, Lalitha Kameshwari; Tanwar, Aditi

2018-01-01

The past 2 decades witnessed the strengthening of evidence favoring the role of neoadjuvant chemoradiation (CHRT) in the treatment of locally advanced rectal cancer. The study aims to evaluate the response and acute toxicities to neoadjuvant CHRT using intensity-modulated radiotherapy (IMRT) in the treatment of rectal cancer. Predictive factors to achieve pathological complete response (pCR) were analyzed, as a secondary endpoint. All consecutive patients who underwent IMRT as part of neoadjuvant CHRT in the treatment of rectal cancer between August 2014 and December 2016 at a tertiary cancer care center were accrued for the study. The cohort underwent CHRT with IMRT technique at a dose of 50.4 Gy in 28 fractions concurrent with continuous infusion of 5 fluorouracil during the first and the last 4 days of CHRT. Surgery was performed 6 weeks later and the pathological response to CHRT was noted. Forty-three subjects were accrued for the study. Radiation dermatitis and diarrhea were the only observed grade ≥3 acute toxicities. Sphincter preservation rate (SPR) was 43.3%. pCR was observed in 32.6%. Univariate and multivariate logistic regression showed that carcinoembryonic antigen was the only independent predictive factor to achieve pCR. IMRT as part of neoadjuvant CHRT in the treatment of locally advanced rectal cancer is well tolerated and gives comparable results with respect to earlier studies in terms of pathological response and SPR. Further randomized controlled studies are needed to firmly state that IMRT is superior to 3-dimensional conformal radiotherapy.

Treatment of folliculitis decalvans using intensity-modulated radiation via tomotherapy.

PubMed

Elsayad, Khaled; Kriz, Jan; Haverkamp, Uwe; Plachouri, Kerasia-Maria; Jeskowiak, Antonia; Sunderkötter, Cord; Eich, Hans Theodor

2015-11-01

Folliculitis decalvans (FD) is a form of primary neutrophilic scarring alopecia that is characterized clinically by chronic suppurative folliculitis and often associated with pruritus or even pain. Treatment of FD is often difficult. Herein, we report a case of recalcitrant and painful folliculitis decalvans refractory to antibiotic and anti-inflammatory therapies, which was successfully treated by intensity-modulated radiotherapy (IMRT) in order to irreversibly eliminate hair follicles that prove to be one etiological trigger. A 45-year-old male patient with a refractory FD presented with a crusting suppurative folliculitis and atrophic scarring patches on the scalp associated with pain and pruritus. We attempted relief of symptoms by reducing scalp inflammation and eliminating hair follicles through radiation. We delivered 11.0 Gy in two radiation series using tomotherapy, 5.0 Gy in 5 equivalent fractions as a first radiation course. The symptoms markedly decreased but did not totally disappear. Therefore, we delivered a second radiation series 4 months later with an additional 6 Gy. This led to almost complete epilation on the scalp and abolished pain and pruritus on the capillitium. The patient was regularly followed up until 26 months after radiotherapy. Draining lesions or exudation did not recur. He only experienced discrete hair regrowth in the occipital region with folliculitis 12 months after radiotherapy. These residual lesions are currently treated with laser epilation therapy. A radical approach to eliminating hair follicles by repeated radiation therapy may induce lasting relief of symptoms in chronic suppurative FD associated with persistent trichodynia.

Multivariable normal-tissue complication modeling of acute esophageal toxicity in advanced stage non-small cell lung cancer patients treated with intensity-modulated (chemo-)radiotherapy.

PubMed

Wijsman, Robin; Dankers, Frank; Troost, Esther G C; Hoffmann, Aswin L; van der Heijden, Erik H F M; de Geus-Oei, Lioe-Fee; Bussink, Johan

2015-10-01

The majority of normal-tissue complication probability (NTCP) models for acute esophageal toxicity (AET) in advanced stage non-small cell lung cancer (AS-NSCLC) patients treated with (chemo-)radiotherapy are based on three-dimensional conformal radiotherapy (3D-CRT). Due to distinct dosimetric characteristics of intensity-modulated radiation therapy (IMRT), 3D-CRT based models need revision. We established a multivariable NTCP model for AET in 149 AS-NSCLC patients undergoing IMRT. An established model selection procedure was used to develop an NTCP model for Grade ⩾2 AET (53 patients) including clinical and esophageal dose-volume histogram parameters. The NTCP model predicted an increased risk of Grade ⩾2 AET in case of: concurrent chemoradiotherapy (CCR) [adjusted odds ratio (OR) 14.08, 95% confidence interval (CI) 4.70-42.19; p<0.001], increasing mean esophageal dose [Dmean; OR 1.12 per Gy increase, 95% CI 1.06-1.19; p<0.001], female patients (OR 3.33, 95% CI 1.36-8.17; p=0.008), and ⩾cT3 (OR 2.7, 95% CI 1.12-6.50; p=0.026). The AUC was 0.82 and the model showed good calibration. A multivariable NTCP model including CCR, Dmean, clinical tumor stage and gender predicts Grade ⩾2 AET after IMRT for AS-NSCLC. Prior to clinical introduction, the model needs validation in an independent patient cohort. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

A dose optimization method for electron radiotherapy using randomized aperture beams

NASA Astrophysics Data System (ADS)

Engel, Konrad; Gauer, Tobias

2009-09-01

The present paper describes the entire optimization process of creating a radiotherapy treatment plan for advanced electron irradiation. Special emphasis is devoted to the selection of beam incidence angles and beam energies as well as to the choice of appropriate subfields generated by a refined version of intensity segmentation and a novel random aperture approach. The algorithms have been implemented in a stand-alone programme using dose calculations from a commercial treatment planning system. For this study, the treatment planning system Pinnacle from Philips has been used and connected to the optimization programme using an ASCII interface. Dose calculations in Pinnacle were performed by Monte Carlo simulations for a remote-controlled electron multileaf collimator (MLC) from Euromechanics. As a result, treatment plans for breast cancer patients could be significantly improved when using randomly generated aperture beams. The combination of beams generated through segmentation and randomization achieved the best results in terms of target coverage and sparing of critical organs. The treatment plans could be further improved by use of a field reduction algorithm. Without a relevant loss in dose distribution, the total number of MLC fields and monitor units could be reduced by up to 20%. In conclusion, using randomized aperture beams is a promising new approach in radiotherapy and exhibits potential for further improvements in dose optimization through a combination of randomized electron and photon aperture beams.

Feasibility study of an intensity-modulated radiation model for the study of erectile dysfunction.

PubMed

Koontz, Bridget F; Yan, Hui; Kimura, Masaki; Vujaskovic, Zeljko; Donatucci, Craig; Yin, Fang-Fang

2011-02-01

Preclinical studies of radiotherapy (RT) induced erectile dysfunction (ED) have been limited by radiation toxicity when using large fields. To develop a protocol of rat prostate irradiation using techniques mimicking the current clinical standard of intensity modulated radiotherapy (IMRT). Quality assurance (QA) testing of plan accuracy, animal health 9 weeks after RT, and intracavernosal pressure (ICP) measurement on cavernosal nerve stimulation. Computed tomography-based planning was used to develop a stereotactic radiosurgery (SRS) treatment plan for five young adult male Sprague-Dawley rats. Two treatment planning strategies were utilized to deliver 20 Gy in a single fraction: three-dimensional dynamic conformal arc and intensity-modulated arc (RapidArc). QA testing was performed for each plan type. Treatment was delivered using a NovalisTX (Varian Medical Systems) with high-definition multi-leaf collimators using on-board imaging prior to treatment. Each animal was evaluated for ED 2 months after treatment by nerve stimulation and ICP measurement. The mean prostate volume and target volume (5 mm expansion of prostate) for the five animals was 0.36 and 0.66 cm3, respectively. Both conformal and RapidArc plans provided at least 95% coverage of the target volume, with rapid dose fall-off. QA plans demonstrated strong agreement between doses of calculated and delivered plans, although the conformal arc plan was more homogenous in treatment delivery. Treatment was well tolerated by the animals with no toxicity out to 9 weeks. Compared with control animals, significant reduction in ICP/mean arterial pressure, maximum ICP, and ICP area under the curve were noted. Tightly conformal dynamic arc prostate irradiation is feasible and results in minimal toxicity and measurable changes in erectile function. © 2010 International Society for Sexual Medicine.

Risk Factors for Hearing Loss in Patients Treated With Intensity-Modulated Radiotherapy for Head-and-Neck Tumors

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

Zuur, Charlotte L.; Simis, Yvonne J.; Lamers, Emmy A.

2009-06-01

Purpose: Radiotherapy (RT) is a common treatment of head-and-neck carcinoma. The objective of this study was to perform a prospective multivariate assessment of the dose-effect relationship between intensity-modulated RT and hearing loss. Methods and Materials: Pure tone audiometry at 0.250-16 kHz was obtained before and after treatment in 101 patients (202 ears). All patients received full-course intensity-modulated RT (range, 56-70 Gy), with a median cochlear dose of 11.4 Gy (range, 0.2-69.7). Results: Audiometry was performed 1 week before and a median of 9 weeks (range, 1-112) after treatment. The mean hearing deterioration at pure tone average air-conduction 1-2-4 kHz wasmore » small (from 28.6 dB HL to 30.1 dB HL). However, individual patients showed clinically significant hearing loss, with 10-dB threshold shift incidences of 13% and 18% at pure tone averages air-conduction 1-2-4 kHz and 8-10-12.5 kHz, respectively. Post-treatment hearing capability was unfavorable in the case of greater inner ear radiation doses (p <0.0001), unfavorable baseline hearing capability (p <0.0001), green-eyed patients (p <0.0001), and older age (p <0.0001). Using multivariate analysis, a prediction of individual hearing capabiltity after treatment was made. Conclusion: RT-induced hearing loss in the mean population is modest. However, clinically significant hearing loss was observed in older patients with green eyes and unfavorable pretreatment hearing. In these patients, the intended radiation dose may be adjusted according to the proposed predictive model, aiming to decrease the risk of ototoxicity.« less

The dosimetric impact of inversely optimized arc radiotherapy plan modulation for real-time dynamic MLC tracking delivery.

PubMed

Falk, Marianne; Larsson, Tobias; Keall, Paul; Chul Cho, Byung; Aznar, Marianne; Korreman, Stine; Poulsen, Per; Munck Af Rosenschold, Per

2012-03-01

Real-time dynamic multileaf collimator (MLC) tracking for management of intrafraction tumor motion can be challenging for highly modulated beams, as the leaves need to travel far to adjust for target motion perpendicular to the leaf travel direction. The plan modulation can be reduced by using a leaf position constraint (LPC) that reduces the difference in the position of adjacent MLC leaves in the plan. The purpose of this study was to investigate the impact of the LPC on the quality of inversely optimized arc radiotherapy plans and the effect of the MLC motion pattern on the dosimetric accuracy of MLC tracking delivery. Specifically, the possibility of predicting the accuracy of MLC tracking delivery based on the plan modulation was investigated. Inversely optimized arc radiotherapy plans were created on CT-data of three lung cancer patients. For each case, five plans with a single 358° arc were generated with LPC priorities of 0 (no LPC), 0.25, 0.5, 0.75, and 1 (highest possible LPC), respectively. All the plans had a prescribed dose of 2 Gy × 30, used 6 MV, a maximum dose rate of 600 MU/min and a collimator angle of 45° or 315°. To quantify the plan modulation, an average adjacent leaf distance (ALD) was calculated by averaging the mean adjacent leaf distance for each control point. The linear relationship between the plan quality [i.e., the calculated dose distributions and the number of monitor units (MU)] and the LPC was investigated, and the linear regression coefficient as well as a two tailed confidence level of 95% was used in the evaluation. The effect of the plan modulation on the performance of MLC tracking was tested by delivering the plans to a cylindrical diode array phantom moving with sinusoidal motion in the superior-inferior direction with a peak-to-peak displacement of 2 cm and a cycle time of 6 s. The delivery was adjusted to the target motion using MLC tracking, guided in real-time by an infrared optical system. The dosimetric results were evaluated using gamma index evaluation with static target measurements as reference. The plan quality parameters did not depend significantly on the LPC (p ≥ 0.066), whereas the ALD depended significantly on the LPC (p < 0.001). The gamma index failure rate depended significantly on the ALD, weighted to the percentage of the beam delivered in each control point of the plan (ALD(w)) when MLC tracking was used (p < 0.001), but not for delivery without MLC tracking (p ≥ 0.342). The gamma index failure rate with the criteria of 2% and 2 mm was decreased from > 33.9% without MLC tracking to <31.4% (LPC 0) and <2.2% (LPC 1) with MLC tracking. The results indicate that the dosimetric robustness of MLC tracking delivery of an inversely optimized arc radiotherapy plan can be improved by incorporating leaf position constraints in the objective function without otherwise affecting the plan quality. The dosimetric robustness may be estimated prior to delivery by evaluating the ALD(w) of the plan.

Relative plan robustness of step-and-shoot vs rotational intensity–modulated radiotherapy on repeat computed tomographic simulation for weight loss in head and neck cancer

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

Thomson, David J.; The University of Manchester, Manchester Academic Health Science Centre, Institute of Cancer Sciences, Manchester; Beasley, William J.

Introduction: Interfractional anatomical alterations may have a differential effect on the dose delivered by step-and-shoot intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT). The increased degrees of freedom afforded by rotational delivery may increase plan robustness (measured by change in target volume coverage and doses to organs at risk [OARs]). However, this has not been evaluated for head and neck cancer. Materials and methods: A total of 10 patients who required repeat computed tomography (CT) simulation and replanning during head and neck IMRT were included. Step-and-shoot IMRT and VMAT plans were generated from the original planning scan. The initial andmore » second CT simulation scans were fused and targets/OAR contours transferred, reviewed, and modified. The plans were applied to the second CT scan and doses recalculated without repeat optimization. Differences between step-and-shoot IMRT and VMAT for change in target volume coverage and doses to OARs between first and second CT scans were compared by Wilcoxon signed rank test. Results: There were clinically relevant dosimetric changes between the first and the second CT scans for both the techniques (reduction in mean D{sub 95%} for PTV2 and PTV3, D{sub min} for CTV2 and CTV3, and increased mean doses to the parotid glands). However, there were no significant differences between step-and-shoot IMRT and VMAT for change in any target coverage parameter (including D{sub 95%} for PTV2 and PTV3 and D{sub min} for CTV2 and CTV3) or dose to any OARs (including parotid glands) between the first and the second CT scans. Conclusions: For patients with head and neck cancer who required replanning mainly due to weight loss, there were no significant differences in plan robustness between step-and-shoot IMRT and VMAT. This information is useful with increased clinical adoption of VMAT.« less

Robust optimization in lung treatment plans accounting for geometric uncertainty.

PubMed

Zhang, Xin; Rong, Yi; Morrill, Steven; Fang, Jian; Narayanasamy, Ganesh; Galhardo, Edvaldo; Maraboyina, Sanjay; Croft, Christopher; Xia, Fen; Penagaricano, Jose

2018-05-01

Robust optimization generates scenario-based plans by a minimax optimization method to find optimal scenario for the trade-off between target coverage robustness and organ-at-risk (OAR) sparing. In this study, 20 lung cancer patients with tumors located at various anatomical regions within the lungs were selected and robust optimization photon treatment plans including intensity modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT) plans were generated. The plan robustness was analyzed using perturbed doses with setup error boundary of ±3 mm in anterior/posterior (AP), ±3 mm in left/right (LR), and ±5 mm in inferior/superior (IS) directions from isocenter. Perturbed doses for D 99 , D 98 , and D 95 were computed from six shifted isocenter plans to evaluate plan robustness. Dosimetric study was performed to compare the internal target volume-based robust optimization plans (ITV-IMRT and ITV-VMAT) and conventional PTV margin-based plans (PTV-IMRT and PTV-VMAT). The dosimetric comparison parameters were: ITV target mean dose (D mean ), R 95 (D 95 /D prescription ), Paddick's conformity index (CI), homogeneity index (HI), monitor unit (MU), and OAR doses including lung (D mean , V 20 Gy and V 15 Gy ), chest wall, heart, esophagus, and maximum cord doses. A comparison of optimization results showed the robust optimization plan had better ITV dose coverage, better CI, worse HI, and lower OAR doses than conventional PTV margin-based plans. Plan robustness evaluation showed that the perturbed doses of D 99 , D 98 , and D 95 were all satisfied at least 99% of the ITV to received 95% of prescription doses. It was also observed that PTV margin-based plans had higher MU than robust optimization plans. The results also showed robust optimization can generate plans that offer increased OAR sparing, especially for normal lungs and OARs near or abutting the target. Weak correlation was found between normal lung dose and target size, and no other correlation was observed in this study. © 2018 University of Arkansas for Medical Sciences. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.

Optimal Fisher Discriminant Ratio for an Arbitrary Spatial Light Modulator

NASA Technical Reports Server (NTRS)

Juday, Richard D.

1999-01-01

Optimizing the Fisher ratio is well established in statistical pattern recognition as a means of discriminating between classes. I show how to optimize that ratio for optical correlation intensity by choice of filter on an arbitrary spatial light modulator (SLM). I include the case of additive noise of known power spectral density.

A review of stereotactic body radiotherapy – is volumetric modulated arc therapy the answer?

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

Sapkaroski, Daniel, E-mail: daniel.sapkaroski@gmail.com; Osborne, Catherine; Knight, Kellie A

2015-06-15

Stereotactic body radiotherapy (SBRT) is a high precision radiotherapy technique used for the treatment of small to moderate extra-cranial tumours. Early studies utilising SBRT have shown favourable outcomes. However, major disadvantages of static field SBRT include long treatment times and toxicity complications. Volumetric modulated arc therapy (VMAT) and intensity modulated radiotherapy (IMRT) may potentially mitigate these disadvantages. This review aims to assess the feasibility of emerging VMAT and IMRT-based SBRT treatment techniques and qualify which offers the best outcome for patients, whilst identifying any emerging and advantageous SBRT planning trends. A review and synthesis of data from current literature upmore » to September 2013 was conducted on EMBASE, Medline, PubMed, Science Direct, Proquest central, Google Scholar and the Cochrane Database of Systematic reviews. Only full text papers comparing VMAT and or IMRT and or Static SBRT were included. Ten papers were identified that evaluated the results of VMAT/IMRT SBRT. Five related to medically inoperable stage 1 and 2 non-small-cell lung cancer (NSCLC), three to spinal metastasis, one related to abdominal lymph node malignancies, with the final one looking at pancreatic adenocarcinoma. Overall treatment times with VMAT were reduced by 66–70% for lung, 46–58% for spine, 42% and 21% for lymph node and pancreatic metastasis respectively, planning constraints were met with several studies showing improved organs at risk sparing with IMRT/VMAT to static SBRT. Both IMRT and VMAT were able to meet all planning constraints in the studies reviewed, with VMAT offering the greatest treatment efficiency. Early clinical outcomes with VMAT and IMRT SBRT have demonstrated excellent local control and favourable survival outcomes.« less

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 and compares favorably with published series for the treatment of prostate cancer. PMID:25210465

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

PubMed

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

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. 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. 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. 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 and compares favorably with published series for the treatment of prostate cancer.

Intensity-modulated radiation therapy followed by GDP chemotherapy for newly diagnosed stage I/II extranodal natural killer/T cell lymphoma, nasal type.

PubMed

Huang, Yu; Yang, Jianliang; Liu, Peng; Zhou, Shengyu; Gui, Lin; He, Xiaohui; Qin, Yan; Zhang, Changgong; Yang, Sheng; Xing, Puyuan; Sun, Yan; Shi, Yuankai

2017-09-01

Extranodal natural killer (NK)/T cell lymphoma, nasal type (ENKTL) is an aggressive non-Hodgkin lymphoma and the majority of ENKTL cases are diagnosed at the localized stage. Radiotherapy in combination with chemotherapy has been used for localized ENKTL, but the optimal combination treatment modality and the best first-line chemotherapy regimen have not been defined. In this retrospective study, 44 patients with newly diagnosed, stages I/II ENKTL were enrolled and received intensity-modulated radiation therapy (IMRT, 50-56 Gy) followed by GDP (gemcitabine, dexamethasone, and cisplatin) chemotherapy. The median number of chemotherapy cycles per patient was 4 (range, 2-6 cycles). At the end of treatment, the overall response rate was 95% (42/44), including 39 patients (89%) who attained complete response. Two patients developed systemic progression after IMRT. With a median follow-up of 37.5 months, the 3-year overall survival (OS) rate and progression-free survival (PFS) rate were 85% (95% CI, 74 to 96%) and 77% (95% CI, 64 to 91%), respectively. Locoregional and systemic failure rates for this treatment were 9% (4/44) and 14% (6/44), respectively. The most common grades 3 to 4 adverse events included leukopenia (37%), neutropenia (34%), and mucositis (25%). No treatment-related deaths were observed. This study suggested high efficacy and low toxicity of IMRT followed by GDP regimen chemotherapy for newly diagnosed stage I/II ENKTL patients. These results require further investigation in prospective trials.

[Effect of intensity modulated radiation therapy on oral mucosa and immune function in patients with nasopharyngeal carcinoma].

PubMed

Liang, Shaoqiang; Zhang, Ning; Chen, Lusi; Zhang, Yang; Zheng, Zhenhe; Luo, Weijun; Xu, Tao; Lü, Zhiqian; Li, Shao'en

2018-05-28

To study the potential effects of intensity modulated radiation therapy (IMRT) on clinical efficacy, oral mucosa reaction and immunological foundation; and to explore the effect of immunological changes on clinical efficacy and oral mucosa reaction in patients with nasopharyngeal carcinoma.
 Methods: A total of 200 patients with nasopharyngeal carcinoma, who came from First Department of Nasopharyngeal Radiotherapy, the First People's Hospital of Foshan from October 2008 to November 2011, were selected. The patients were treated with nasopharyngeal radiotherapy, and divided into an observation group and a control group (n=100 in each group). The control group underwent common conventional two-dimensional radiotherapy treatment, while the observation group underwent IMRT. The 5-year survival rates and recurrence rates were recorded at follow-up. After the radiotherapy, the oral mucosa in the patients were evaluated by the classification standard of acute radioactive mucositis by American Radiotherapy Oncology Group (RTOG), and the number of T lymphocyte subsets before and after treatment was detected.
 Results: There were significant difference in non-regional-recurrence survival rate, disease-free survival rate, local recurrence rate between the above 2 groups (all P<0.05), but no significant difference in the distant metastasis-free survival rate (P>0.05). The acute oral mucosa reactions of grade 1, 2, 3, 4 in the control group were 8.00%, 20.00%, 12.00%, 7.00%, respectively, and those were 7.00%, 22.00%, 15.00%, 1.00% respectively. There was no significant difference in the acute response of oral mucosa in grade 1, 2 and 3 in the 2 groups (all P>0.05), but there was significant difference in the grade 4 (P<0.05). There were significantly difference in CD8+, CD4+/ CD8+ and CD4+ T lymphocyte subsets before and after treatment in the above 2 groups (all P<0.01); there were also significantly difference after treatment between the observation group and the control group (all P<0.01).
 Conclusion: In the process of treatment in patients with nasopharyngeal carcinoma, the use of IMRT on the basis of chemotherapy is more effective than the conventional two-dimensional radiotherapy, which can reduce the proportion of grade 4 (severe) acute oral mucosa reaction. It may be related to the protective effect of IMRT on immune function in the patients.

Dosimetric comparison of intensity modulated radiotherapy and three-dimensional conformal radiotherapy in patients with gynecologic malignancies: a systematic review and meta-analysis

PubMed Central

2012-01-01

Background To quantitatively evaluate the safety and related-toxicities of intensity modulated radiotherapy (IMRT) dose–volume histograms (DVHs), as compared to the conventional three-dimensional conformal radiotherapy (3D-CRT), in gynecologic malignancy patients by systematic review of the related publications and meta-analysis. Methods Relevant articles were retrieved from the PubMed, Embase, and Cochrane Library databases up to August 2011. Two independent reviewers assessed the included studies and extracted data. Pooled average percent irradiated volumes of adjacent non-cancerous tissues were calculated and compared between IMRT and 3D-CRT for a range of common radiation doses (5-45Gy). Results In total, 13 articles comprised of 222 IMRT-treated and 233 3D-CRT-treated patients were included. For rectum receiving doses ≥30 Gy, the IMRT pooled average irradiated volumes were less than those from 3D-CRT by 26.40% (30 Gy, p = 0.004), 27.00% (35 Gy, p = 0.040), 37.30% (40 Gy, p = 0.006), and 39.50% (45 Gy, p = 0.002). Reduction in irradiated small bowel was also observed for IMRT-delivered 40 Gy and 45 Gy (by 17.80% (p = 0.043) and 17.30% (p = 0.012), respectively), as compared with 3D-CRT. However, there were no significant differences in the IMRT and 3D-CRT pooled average percent volumes of irradiated small bowel or rectum from lower doses, or in the bladder or bone marrow from any of the doses. IMRT-treated patients did not experience more severe acute or chronic toxicities than 3D-CRT-treated patients. Conclusions IMRT-delivered high radiation dose produced significantly less average percent volumes of irradiated rectum and small bowel than 3D-CRT, but did not differentially affect the average percent volumes in the bladder and bone marrow. PMID:23176540

Implementation of an image guided intensity-modulated protocol for post-prostatectomy radiotherapy: planning data and acute toxicity outcomes.

PubMed

Chua, Benjamin; Min, Myo; Wood, Maree; Edwards, Sarah; Hoffmann, Matthew; Greenham, Stuart; Kovendy, Andrew; McKay, Michael J; Shakespeare, Thomas P

2013-08-01

There is substantial interest in implementation of image-guided intensity-modulated radiotherapy (IG-IMRT) in the post-prostatectomy setting. We describe our implementation of IG-IMRT, and examine how often published organ-at-risk (OAR) constraints were met. Furthermore, we evaluate the incidence of acute genitourinary and gastrointestinal toxicities when patients were treated according to our protocol. Patients were eligible if they received post-prostatectomy radiotherapy (PPRT). Planning data were collected prospectively, and toxicity assessments were collected before, during and after treatment. Seventy-five eligible patients received either 64 Gy (19%) or 66 Gy (81%) in a single phase to the prostate bed. Suggested rectal dose-constraints of V40Gy < 60% and V60Gy < 40% were met in 64 (85%) and 75 (100%) patients, respectively. IMRT-specific rectal dose-constraints of V40Gy < 35% and V65Gy < 17% were achieved in 5 (7%) and 57 (76%) of patients. Bladder dose-constraint (V50Gy < 50%) was met in 58 (77%) patients. Two patients (3%) experienced new grade 3 genitourinary toxicity and one patient (1%) experienced new grade 3 gastroinestinal toxicity. All grade 3 toxicities had improved by 3-month review. Overall deterioration in urinary and gastrointestinal symptoms occurred in 33 (44%) and 35 (47%) of patients respectively. We report on our implementation of PPRT which takes into account nationally adopted guidelines, with a margin reduction supported by use of daily image guidance. Non-IMRT OAR constraints were met in most cases. IMRT-specific constraints were less often achieved despite margin reductions, suggesting the need for review of guidelines. Severe toxicity was rare, and most patients did not experience deterioration in urinary or bowel function attributable to radiotherapy. © 2013 The Authors. Journal of Medical Imaging and Radiation Oncology © 2013 The Royal Australian and New Zealand College of Radiologists.

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

PubMed

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

2012-07-01

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

Intensity-modulated radiotherapy for locally advanced non-small-cell lung cancer: a dose-escalation planning study.

PubMed

Lievens, Yolande; Nulens, An; Gaber, Mousa Amr; Defraene, Gilles; De Wever, Walter; Stroobants, Sigrid; Van den Heuvel, Frank

2011-05-01

To evaluate the potential for dose escalation with intensity-modulated radiotherapy (IMRT) in positron emission tomography-based radiotherapy planning for locally advanced non-small-cell lung cancer (LA-NSCLC). For 35 LA-NSCLC patients, three-dimensional conformal radiotherapy and IMRT plans were made to a prescription dose (PD) of 66 Gy in 2-Gy fractions. Dose escalation was performed toward the maximal PD using secondary endpoint constraints for the lung, spinal cord, and heart, with de-escalation according to defined esophageal tolerance. Dose calculation was performed using the Eclipse pencil beam algorithm, and all plans were recalculated using a collapsed cone algorithm. The normal tissue complication probabilities were calculated for the lung (Grade 2 pneumonitis) and esophagus (acute toxicity, grade 2 or greater, and late toxicity). IMRT resulted in statistically significant decreases in the mean lung (p <.0001) and maximal spinal cord (p = .002 and 0005) doses, allowing an average increase in the PD of 8.6-14.2 Gy (p ≤.0001). This advantage was lost after de-escalation within the defined esophageal dose limits. The lung normal tissue complication probabilities were significantly lower for IMRT (p <.0001), even after dose escalation. For esophageal toxicity, IMRT significantly decreased the acute NTCP values at the low dose levels (p = .0009 and p <.0001). After maximal dose escalation, late esophageal tolerance became critical (p <.0001), especially when using IMRT, owing to the parallel increases in the esophageal dose and PD. In LA-NSCLC, IMRT offers the potential to significantly escalate the PD, dependent on the lung and spinal cord tolerance. However, parallel increases in the esophageal dose abolished the advantage, even when using collapsed cone algorithms. This is important to consider in the context of concomitant chemoradiotherapy schedules using IMRT. Copyright © 2011 Elsevier Inc. All rights reserved.

Quality of Life and Survival Outcome for Patients With Nasopharyngeal Carcinoma Receiving Three-Dimensional Conformal Radiotherapy vs. Intensity-Modulated Radiotherapy-A Longitudinal Study

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

Fang, F.-M.; Kaohsiung Chang Gung Head and Neck Oncology Group, Chang Gung Memorial Hospital-Kaohsiung Medical Center, Chang Gung University College of Medicine, Kaohsiung Hsien, Taiwan; Chien, C.-Y.

2008-10-01

Purpose: To investigate the changes of quality of life (QoL) and survival outcomes for patients with nasopharyngeal carcinoma (NPC) treated by three-dimensional conformal radiotherapy (3D-CRT) vs. intensity-modulated radiotherapy (IMRT). Methods and Materials: Two hundred and three newly diagnosed NPC patients, who were curatively treated by 3D-CRT (n = 93) or IMRT (n = 110) between March 2002 and July 2004, were analyzed. The distributions of clinical stage according to American Joint Committee on Cancer 1997 were I: 15 (7.4%), II: 78 (38.4%), III: 74 (36.5%), and IV: 36 (17.7%). QoL was longitudinally assessed by the European Organization for Research andmore » Treatment of Cancer (EORTC) QLQ-C30 and the EORTC QLQ-H and N35 questionnaires at the five time points: before RT, during RT (36 Gy), and 3 months, 12 months, and 24 months after RT. Results: The 3-year locoregional control, metastasis-free survival, and overall survival rates were 84.8%, 76.7%, and 81.7% for the 3D-CRT group, respectively, compared with 84.2%, 82.6%, and 85.4% for the IMRT group (p value > 0.05). A general trend of maximal deterioration in most QoL scales was observed during RT, followed by a gradual recovery thereafter. There was no significant difference in most scales between the two groups at each time point. The exception was that patients treated by IMRT had a both statistically and clinically significant improvement in global QoL, fatigue, taste/smell, dry mouth, and feeling ill at the time point of 3 months after RT. Conclusions: The potential advantage of IMRT over 3D-CRT in treating NPC patients might occur in QoL outcome during the recovery phase of acute toxicity.« less

No increase in toxicity of pelvic irradiation when intensity modulation is employed: clinical and dosimetric data of 208 patients treated with post-prostatectomy radiotherapy.

PubMed

Jereczek-Fossa, Barbara A; Ciardo, Delia; Ferrario, Silvia; Fossati, Piero; Fanetti, Giuseppe; Zerini, Dario; Zannoni, Davide; Fodor, Cristiana; Gerardi, Marianna A; Surgo, Alessia; Muto, Matteo; Cambria, Raffaella; De Cobelli, Ottavio; Orecchia, Roberto

2016-07-01

To compare the toxicity of image-guided intensity-modulated radiotherapy (IG-IMRT) to the pelvis or prostate bed (PB) only. To test the hypothesis that the potentially injurious effect of pelvic irradiation can be counterbalanced by reduced irradiated normal tissue volume using IG-IMRT. Between February 2010 and February 2012, 208 patients with prostate cancer were treated with adjuvant or salvage IG-IMRT to the PB (102 patients, Group PB) or the pelvis and prostate bed (P) (106 patients, Group P). The Radiation Therapy Oncology Group/European Organization for Research and Treatment of Cancer criteria were used to evaluate toxicity. Median follow-up was 27 months. Toxicity G ≥ 2 in Group PB: in the bowel acute and late toxicities were 11.8% and 10%, respectively; urinary acute and late toxicities were 10.8% and 15%, respectively. Toxicity G ≥ 2 in Group P: in the bowel acute and late toxicities were both 13.2%; urinary acute and late toxicities were 13.2% and 15.1%, respectively. No statistical difference in acute or late toxicity between the groups was found (bowel: p = 0.23 and p = 0.89 for acute and late toxicity, respectively; urinary: p = 0.39 and p = 0.66 for acute and late toxicity, respectively). Of the clinical variables, only previous abdominal surgery was correlated with acute bowel toxicity. Dosimetric parameters that correlated with bowel toxicity were identified. The toxicity rates were low and similar in both groups, suggesting that IG-IMRT allows for a safe post-operative irradiation of larger volumes. Further investigation is warranted to exclude bias owing to non-randomized character of the study. Our report shows that modern radiotherapy technology and careful planning allow maintaining the toxicity of pelvic lymph node treatment at the acceptable level, as it is in the case of PB radiotherapy.

A methodology for automatic intensity-modulated radiation treatment planning for lung cancer

NASA Astrophysics Data System (ADS)

Zhang, Xiaodong; Li, Xiaoqiang; Quan, Enzhuo M.; Pan, Xiaoning; Li, Yupeng

2011-07-01

In intensity-modulated radiotherapy (IMRT), the quality of the treatment plan, which is highly dependent upon the treatment planner's level of experience, greatly affects the potential benefits of the radiotherapy (RT). Furthermore, the planning process is complicated and requires a great deal of iteration, and is often the most time-consuming aspect of the RT process. In this paper, we describe a methodology to automate the IMRT planning process in lung cancer cases, the goal being to improve the quality and consistency of treatment planning. This methodology (1) automatically sets beam angles based on a beam angle automation algorithm, (2) judiciously designs the planning structures, which were shown to be effective for all the lung cancer cases we studied, and (3) automatically adjusts the objectives of the objective function based on a parameter automation algorithm. We compared treatment plans created in this system (mdaccAutoPlan) based on the overall methodology with plans from a clinical trial of IMRT for lung cancer run at our institution. The 'autoplans' were consistently better, or no worse, than the plans produced by experienced medical dosimetrists in terms of tumor coverage and normal tissue sparing. We conclude that the mdaccAutoPlan system can potentially improve the quality and consistency of treatment planning for lung cancer.

Intensity modulated radiotherapy with fixed collimator jaws for locoregional left-sided breast cancer irradiation.

PubMed

Wang, Juanqi; Yang, Zhaozhi; Hu, Weigang; Chen, Zhi; Yu, Xiaoli; Guo, Xiaomao

2017-05-16

The purpose of this study is to evaluate the intensity modulated radiotherapy (IMRT) with the fixed collimator jaws technique (FJT) for the left breast and regional lymph node. The targeted breast tissue and the lymph nodes, and the normal tissues were contoured for 16 left-sided breast cancer patients previously treated with radiotherapy after lumpectomy. For each patient, treatment plans using different planning techniques, i.e., volumetric modulated arc therapy (VMAT), tangential IMRT (tangential-IMRT), and IMRT with FJT (FJT-IMRT) were developed for dosimetric comparisons. A dose of 50Gy was prescribed to the planning target volume. The dose-volume histograms were generated, and the paired t-test was used to analyze the dose differences. FJT-IMRT had similar mean heart volume receiving 30Gy (V30 Gy) with tangential-IMRT (1.5% and 1.6%, p = 0.41), but inferior to the VMAT (0.8%, p < 0.001). In the average heart mean dose comparison, FJT-IMRT had the lowest value, and it was 0.6Gy lower than that for the VMAT plans (p < 0.01). A significant dose increase in the contralateral breast and lung was observed in VMAT plans. Compared with tangential-IMRT and VMAT plans, FJT-IMRT reduced the mean dose of thyroid, humeral head and cervical esophageal by 47.6% (p < 0.01) and 45.7% (p < 0.01), 74.3% (p =< 0.01) and 73% (p =< 0.01), and 26.7% (p =< 0.01) and 29.2% (p =< 0.01). In conclusion, compared with tangential-IMRT and VMAT, FJT-IMRT plan has the lowest thyroid, humeral head and cervical esophageal mean dose and it can be a reasonable treatment option for a certain subgroup of patients, such as young left-breast cancer patients and/or patients with previous thyroid disease.

Development of a center for light ion therapy and accurate tumor diagnostics at karolinska institutet and hospital

NASA Astrophysics Data System (ADS)

Brahme, Anders; Lind, Bengt K.

2002-04-01

Radiation therapy is today in a state of very rapid development with new intensity modulated treatment techniques continuously being developed. This has made intensity modulated electron and photon beams almost as powerful as conventional uniform beam proton therapy. To be able to cure also the most advanced hypoxic and radiation resistant tumors of complex local spread, intensity modulated light ion beams are really the ultimate tool and only slightly more expensive than proton therapy. The aim of the new center for ion therapy and tumor diagnostics in Stockholm is to develop radiobiologically optimized 3-dimensional pencil beam scanning techniques. Beside the "classical" approaches using low ionization density hydrogen ions (protons, but also deuterons and tritium nuclei) and high ionization density carbon ions, two new approaches will be developed. In the first one lithium or beryllium ions, that induce the least detrimental biological effect to normal tissues for a given biological effect in a small volume of the tumor, will be key particles. In the second approach, referred patients will be given a high-dose high-precision "boost" treatment with carbon or oxygen ions during one week preceding the final treatment with conventional radiations in the referring hospital. The rationale behind these approaches is to reduce the high ionization density dose to the normal tissue stroma inside the tumor and to ensure a microscopically uniform dose delivery. The principal idea of the center is to closely integrate ion therapy into the clinical routine and research of a large radiotherapy department. The light ion therapy center will therefore be combined with advanced tumor diagnostics including MR and PET-CT imaging to facilitate efficient high-precision high-dose boost treatment of remitted patients. The possibility to do 3D tumor diagnostics and 3D dose delivery verification with the same PET camera will be the ultimate step in high quality adaptive radiation therapy where alterations in the delivered dose can be corrected by subsequent treatments

Interfractional Dose Variations in Intensity-Modulated Radiotherapy With Breath-Hold for Pancreatic Cancer

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

Nakamura, Mitsuhiro; Shibuya, Keiko, E-mail: kei@kuhp.kyoto-u.ac.jp; Nakamura, Akira

2012-04-01

Purpose: To investigate the interfractional dose variations for intensity-modulated radiotherapy (RT) combined with breath-hold (BH) at end-exhalation (EE) for pancreatic cancer. Methods and Materials: A total of 10 consecutive patients with pancreatic cancer were enrolled. Each patient was fixed in the supine position on an individualized vacuum pillow with both arms raised. Computed tomography (CT) scans were performed before RT, and three additional scans were performed during the course of chemoradiotherapy using a conventional RT technique. The CT data were acquired under EE-BH conditions (BH-CT) using a visual feedback technique. The intensity-modulated RT plan, which used five 15-MV coplanar ports,more » was designed on the initial BH-CT set with a prescription dose of 39 Gy at 2.6 Gy/fraction. After rigid image registration between the initial and subsequent BH-CT scans, the dose distributions were recalculated on the subsequent BH-CT images under the same conditions as in planning. Changes in the dose-volume metrics of the gross tumor volume (GTV), clinical target volume (CTV = GTV + 5 mm), stomach, and duodenum were evaluated. Results: For the GTV and clinical target volume (CTV), the 95th percentile of the interfractional variations in the maximal dose, mean dose, dose covering 95% volume of the region of structure, and percentage of the volume covered by the 90% isodose line were within {+-}3%. Although the volume covered by the 39 Gy isodose line for the stomach and duodenum did not exceed 0.1 mL at planning, the volume covered by the 39 Gy isodose line for these structures was up to 11.4 cm{sup 3} and 1.8 cm{sup 3}, respectively. Conclusions: Despite variations in the gastrointestinal state and abdominal wall position at EE, the GTV and CTV were mostly ensured at the planned dose, with the exception of 1 patient. Compared with the duodenum, large variations in the stomach volume receiving high-dose radiation were observed, which might be beyond the negligible range in achieving dose escalation with intensity-modulated RT combined with BH at EE.« less

Proton Radiotherapy for High-Risk Pediatric Neuroblastoma: Early Outcomes and Dose Comparison

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

Hattangadi, Jona A.; Rombi, Barbara; Provincial Agency for Proton Therapy, Trento

2012-07-01

Purpose: To report the early outcomes for children with high-risk neuroblastoma treated with proton radiotherapy (RT) and to compare the dose distributions for intensity-modulated photon RT (IMRT), three-dimensional conformal proton RT (3D-CPT), and intensity-modulated proton RT to the postoperative tumor bed. Methods and Materials: All patients with high-risk (International Neuroblastoma Staging System Stage III or IV) neuroblastoma treated between 2005 and 2010 at our institution were included. All patients received induction chemotherapy, surgical resection of residual disease, high-dose chemotherapy with stem cell rescue, and adjuvant 3D-CPT to the primary tumor sites. The patients were followed with clinical examinations, imaging, andmore » laboratory testing every 6 months to monitor disease control and side effects. IMRT, 3D-CPT, and intensity-modulated proton RT plans were generated and compared for a representative case of adjuvant RT to the primary tumor bed followed by a boost. Results: Nine patients were treated with 3D-CPT. The median age at diagnosis was 2 years (range 10 months to 4 years), and all patients had Stage IV disease. All patients had unfavorable histologic characteristics (poorly differentiated histologic features in 8, N-Myc amplification in 6, and 1p/11q chromosomal abnormalities in 4). The median tumor size at diagnosis was 11.4 cm (range 7-16) in maximal dimension. At a median follow-up of 38 months (range 11-70), there were no local failures. Four patients developed distant failure, and, of these, two died of disease. Acute side effects included Grade 1 skin erythema in 5 patients and Grade 2 anorexia in 2 patients. Although comparable target coverage was achieved with all three modalities, proton therapy achieved substantial normal tissue sparing compared with IMRT. Intensity-modulated proton RT allowed additional sparing of the kidneys, lungs, and heart. Conclusions: Preliminary outcomes reveal excellent local control with proton therapy for high-risk neuroblastoma, although distant failures continu to occur. Dosimetric comparisons demonstrate the advantage of proton RT compared with IMRT in this setting, allowing more conformal treatment and better normal tissue sparing.« less

Uses of megavoltage digital tomosynthesis in radiotherapy

NASA Astrophysics Data System (ADS)

Sarkar, Vikren

With the advent of intensity modulated radiotherapy, radiation treatment plans are becoming more conformal to the tumor with the decreasing margins. It is therefore of prime importance that the patient be positioned correctly prior to treatment. Therefore, image guided treatment is necessary for intensity modulated radiotherapy plans to be implemented successfully. Current advanced imaging devices require costly hardware and software upgrade, and radiation imaging solutions, such as cone beam computed tomography, may introduce extra radiation dose to the patient in order to acquire better quality images. Thus, there is a need to extend current existing imaging device ability and functions while reducing cost and radiation dose. Existing electronic portal imaging devices can be used to generate computed tomography-like tomograms through projection images acquired over a small angle using the technique of cone-beam digital tomosynthesis. Since it uses a fraction of the images required for computed tomography reconstruction, use of this technique correspondingly delivers only a fraction of the imaging dose to the patient. Furthermore, cone-beam digital tomosynthesis can be offered as a software-only solution as long as a portal imaging device is available. In this study, the feasibility of performing digital tomosynthesis using individually-acquired megavoltage images from a charge coupled device-based electronic portal imaging device was investigated. Three digital tomosynthesis reconstruction algorithms, the shift-and-add, filtered back-projection, and simultaneous algebraic reconstruction technique, were compared considering the final image quality and radiation dose during imaging. A software platform, DART, was created using a combination of the Matlab and C++ languages. The platform allows for the registration of a reference Cone Beam Digital Tomosynthesis (CBDT) image against a daily acquired set to determine how to shift the patient prior to treatment. Finally, the software was extended to investigate if the digital tomosynthesis dataset could be used in an adaptive radiotherapy regimen through the use of the Pinnacle treatment planning software to recalculate dose delivered. The feasibility study showed that the megavoltage CBDT visually agreed with corresponding megavoltage computed tomography images. The comparative study showed that the best compromise between imaging quality and imaging dose is obtained when 11 projection images, acquired over an imaging angle of 40°, are used with the filtered back-projection algorithm. DART was successfully used to register reference and daily image sets to within 1 mm in-plane and 2.5 mm out of plane. The DART platform was also effectively used to generate updated files that the Pinnacle treatment planning system used to calculate updated dose in a rigidly shifted patient. These doses were then used to calculate a cumulative dose distribution that could be used by a physician as reference to decide when the treatment plan should be updated. In conclusion, this study showed that a software solution is possible to extend existing electronic portal imaging devices to function as cone-beam digital tomosynthesis devices and achieve daily requirement for image guided intensity modulated radiotherapy treatments. The DART platform also has the potential to be used as a part of adaptive radiotherapy solution.

New Language and Old Problems in Breast Cancer Radiotherapy.

PubMed

Chiricuţă, Ion Christian

2017-01-01

New developments in breast cancer radiotherapy make possible new standards in treatment recommandations based on international guidelines. Developments in radiotherapy irradiation techniques from 2D to 3D-Conformal RT and to IMRT (Intensity Modulated Arc Therapy) make possible to reduce the usual side effects on the organs at risk as: skin, lung, miocard, bone, esophagus and brahial plexus. Dispite of all these progresses acute and late side effects are present. Side effects are as old as the radiotherapy was used. New solutions are available now by improving irradiation techniques. New techniques as sentinel node procedure (SNP) or partial breast irradiation (PBRT) and immediate breast reconstruction with silicon implants (IBRIS) make necessary new considerations regarding the target volume delineations. A new language for definition of gross tumor volume (GTV), clinical target volume (CTV) based on the new diagnostic methods as PET/CT,nonaparticle MRI will have real impact on target delineation and irradiation techniques. "The new common language in breast cancer therapy" would be the first step to improve the endresults and finally the quality of life of the patients. Celsius.

Parotid-sparing intensity modulated versus conventional radiotherapy in head and neck cancer (PARSPORT): a phase 3 multicentre randomised controlled trial

PubMed Central

Nutting, Christopher M; Morden, James P; Harrington, Kevin J; Urbano, Teresa Guerrero; Bhide, Shreerang A; Clark, Catharine; Miles, Elizabeth A; Miah, Aisha B; Newbold, Kate; Tanay, MaryAnne; Adab, Fawzi; Jefferies, Sarah J; Scrase, Christopher; Yap, Beng K; A'Hern, Roger P; Sydenham, Mark A; Emson, Marie; Hall, Emma

2011-01-01

Summary Background Xerostomia is the most common late side-effect of radiotherapy to the head and neck. Compared with conventional radiotherapy, intensity-modulated radiotherapy (IMRT) can reduce irradiation of the parotid glands. We assessed the hypothesis that parotid-sparing IMRT reduces the incidence of severe xerostomia. Methods We undertook a randomised controlled trial between Jan 21, 2003, and Dec 7, 2007, that compared conventional radiotherapy (control) with parotid-sparing IMRT. We randomly assigned patients with histologically confirmed pharyngeal squamous-cell carcinoma (T1–4, N0–3, M0) at six UK radiotherapy centres between the two radiotherapy techniques (1:1 ratio). A dose of 60 or 65 Gy was prescribed in 30 daily fractions given Monday to Friday. Treatment was not masked. Randomisation was by computer-generated permuted blocks and was stratified by centre and tumour site. Our primary endpoint was the proportion of patients with grade 2 or worse xerostomia at 12 months, as assessed by the Late Effects of Normal Tissue (LENT SOMA) scale. Analyses were done on an intention-to-treat basis, with all patients who had assessments included. Long-term follow-up of patients is ongoing. This study is registered with the International Standard Randomised Controlled Trial register, number ISRCTN48243537. Findings 47 patients were assigned to each treatment arm. Median follow-up was 44·0 months (IQR 30·0–59·7). Six patients from each group died before 12 months and seven patients from the conventional radiotherapy and two from the IMRT group were not assessed at 12 months. At 12 months xerostomia side-effects were reported in 73 of 82 alive patients; grade 2 or worse xerostomia at 12 months was significantly lower in the IMRT group than in the conventional radiotherapy group (25 [74%; 95% CI 56–87] of 34 patients given conventional radiotherapy vs 15 [38%; 23–55] of 39 given IMRT, p=0·0027). The only recorded acute adverse event of grade 2 or worse that differed significantly between the treatment groups was fatigue, which was more prevalent in the IMRT group (18 [41%; 99% CI 23–61] of 44 patients given conventional radiotherapy vs 35 [74%; 55–89] of 47 given IMRT, p=0·0015). At 24 months, grade 2 or worse xerostomia was significantly less common with IMRT than with conventional radiotherapy (20 [83%; 95% CI 63–95] of 24 patients given conventional radiotherapy vs nine [29%; 14–48] of 31 given IMRT; p<0·0001). At 12 and 24 months, significant benefits were seen in recovery of saliva secretion with IMRT compared with conventional radiotherapy, as were clinically significant improvements in dry-mouth-specific and global quality of life scores. At 24 months, no significant differences were seen between randomised groups in non-xerostomia late toxicities, locoregional control, or overall survival. Interpretation Sparing the parotid glands with IMRT significantly reduces the incidence of xerostomia and leads to recovery of saliva secretion and improvements in associated quality of life, and thus strongly supports a role for IMRT in squamous-cell carcinoma of the head and neck. Funding Cancer Research UK (CRUK/03/005). PMID:21236730

Implementation of a volumetric modulated arc therapy treatment planning solution for kidney and adrenal stereotactic body radiation therapy

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

Sonier, Marcus, E-mail: Marcus.Sonier@bccancer.bc.ca; Chu, William; Department of Radiation Oncology, University of Toronto, Toronto, ON

To develop a volumetric modulated arc therapy (VMAT) treatment planning solution in the treatment of primary renal cell carcinoma and oligometastatic adrenal lesions with stereotactic body radiation therapy. Single-arc VMAT plans (n = 5) were compared with clinically delivered step-and-shoot intensity-modulated radiotherapy (IMRT) with planning target volume coverage normalized between techniques. Target volume conformity, organ-at-risk (OAR) dose, treatment time, and monitor units were compared. A VMAT planning solution, created from a combination of arc settings and optimization constraints, auto-generated treatment plans in a single optimization. The treatment planning solution was evaluated on 15 consecutive patients receiving kidney and adrenal stereotacticmore » body radiation therapy. Treatment time was reduced from 13.0 ± 2.6 to 4.0 ± 0.9 minutes for IMRT and VMAT, respectively. The VMAT planning solution generated treatment plans with increased target homogeneity, improved 95% conformity index, and a reduced maximum point dose to nearby OARs but with increased intermediate dose to distant OARs. The conformity of the 95% isodose improved from 1.32 ± 0.39 to 1.12 ± 0.05 for IMRT and VMAT treatment plans, respectively. Evaluation of the planning solution showed clinically acceptable dose distributions for 13 of 15 cases with tight conformity of the prescription isodose to the planning target volume of 1.07 ± 0.04, delivering minimal dose to OARs. The introduction of a stereotactic body radiation therapy VMAT treatment planning solution improves the efficiency of planning and delivery time, producing treatment plans of comparable or superior quality to IMRT in the case of primary renal cell carcinoma and oligometastatic adrenal lesions.« less

Radiation-induced second primary cancer risks from modern external beam radiotherapy for early prostate cancer: impact of stereotactic ablative radiotherapy (SABR), volumetric modulated arc therapy (VMAT) and flattening filter free (FFF) radiotherapy

NASA Astrophysics Data System (ADS)

Murray, Louise J.; Thompson, Christopher M.; Lilley, John; Cosgrove, Vivian; Franks, Kevin; Sebag-Montefiore, David; Henry, Ann M.

2015-02-01

Risks of radiation-induced second primary cancer following prostate radiotherapy using 3D-conformal radiotherapy (3D-CRT), intensity-modulated radiotherapy (IMRT), volumetric modulated arc therapy (VMAT), flattening filter free (FFF) and stereotactic ablative radiotherapy (SABR) were evaluated. Prostate plans were created using 10 MV 3D-CRT (78 Gy in 39 fractions) and 6 MV 5-field IMRT (78 Gy in 39 fractions), VMAT (78 Gy in 39 fractions, with standard flattened and energy-matched FFF beams) and SABR (42.7 Gy in 7 fractions with standard flattened and energy-matched FFF beams). Dose-volume histograms from pelvic planning CT scans of three prostate patients, each planned using all 6 techniques, were used to calculate organ equivalent doses (OED) and excess absolute risks (EAR) of second rectal and bladder cancers, and pelvic bone and soft tissue sarcomas, using mechanistic, bell-shaped and plateau models. For organs distant to the treatment field, chamber measurements recorded in an anthropomorphic phantom were used to calculate OEDs and EARs using a linear model. Ratios of OED give relative radiation-induced second cancer risks. SABR resulted in lower second cancer risks at all sites relative to 3D-CRT. FFF resulted in lower second cancer risks in out-of-field tissues relative to equivalent flattened techniques, with increasing impact in organs at greater distances from the field. For example, FFF reduced second cancer risk by up to 20% in the stomach and up to 56% in the brain, relative to the equivalent flattened technique. Relative to 10 MV 3D-CRT, 6 MV IMRT or VMAT with flattening filter increased second cancer risks in several out-of-field organs, by up to 26% and 55%, respectively. For all techniques, EARs were consistently low. The observed large relative differences between techniques, in absolute terms, were very low, highlighting the importance of considering absolute risks alongside the corresponding relative risks, since when absolute risks are very low, large relative risks become less meaningful. A calculated relative radiation-induced second cancer risk benefit from SABR and FFF techniques was theoretically predicted, although absolute radiation-induced second cancer risks were low for all techniques, and absolute differences between techniques were small.

Further Improvement in Outcomes of Nasopharyngeal Carcinoma With Optimized Radiotherapy and Induction Plus Concomitant Chemotherapy: An Update of the Milan Experience

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

Palazzi, Mauro; Orlandi, Ester; Bossi, Paolo

2009-07-01

Purpose: To report the outcome of a consecutive series of patients with nonmetastatic nasopharyngeal carcinoma (NPC), focusing on the impact of treatment-related factors. Methods and Materials: Between 2000 and 2006, 87 patients with NPC were treated with either conventional (two- or three-dimensional) radiotherapy (RT) or with intensity-modulated RT (IMRT). Of these patients, 81 (93%) received either concomitant CHT (24%) or both induction and concomitant chemotherapy (CHT) (69%). Stage was III in 36% and IV in 39% of patients. Outcomes in this study population were compared with those in the previous series of 171 patients treated during 1990 to 1999. Results:more » With a median follow-up of 46 months, actuarial rates at 3 years were the following: local control, 96%; local-regional control, 93%; distant control (DC), 90%; disease-free survival (DFS), 82%; overall survival, 90%. In Stage III to IV patients, distant control at 3 years was 56% in patients treated with concomitant CHT only and 92% in patients treated with both induction and concomitant CHT (p = 0.014). At multivariate analysis, histology, N-stage, RT technique, and total RT dose had the strongest independent impact on DFS (p < 0.05). Induction CHT had a borderline effect on DC (p = 0.07). Most dosimetric statistics were improved in the group of patients treated with IMRT compared with conventional 3D technique. All outcome endpoints were substantially better in the study population compared with those in the previous series. Conclusions: Outcome of NPC has further improved in the study period compared with the previous decade, with a significant effect of RT technique optimization. The impact of induction CHT remains to be demonstrated in controlled trials.« less

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

PubMed

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

2013-07-01

To introduce a hybrid volumetric modulated arc therapy/intensity modulated radiation therapy (VMAT/IMRT) optimization strategy called FusionArc that combines the delivery efficiency of single-arc VMAT with the potentially desirable intensity modulation possible with IMRT. A beamlet-based inverse planning system was enhanced to combine the advantages of VMAT and IMRT into one comprehensive technique. In the hybrid strategy, baseline single-arc VMAT plans are optimized and then the current cost function gradients with respect to the beamlets are used to define a metric for predicting which beam angles would benefit from further intensity modulation. Beams with the highest metric values (called the gradient factor) are converted from VMAT apertures to IMRT fluence, and the optimization proceeds with the mixed variable set until convergence or until additional beams are selected for conversion. One phantom and two clinical cases were used to validate the gradient factor and characterize the FusionArc strategy. Comparisons were made between standard IMRT, single-arc VMAT, and FusionArc plans with one to five IMRT∕hybrid beams. The gradient factor was found to be highly predictive of the VMAT angles that would benefit plan quality the most from beam modulation. Over the three cases studied, a FusionArc plan with three converted beams achieved superior dosimetric quality with reductions in final cost ranging from 26.4% to 48.1% compared to single-arc VMAT. Additionally, the three beam FusionArc plans required 22.4%-43.7% fewer MU∕Gy than a seven beam IMRT plan. While the FusionArc plans with five converted beams offer larger reductions in final cost--32.9%-55.2% compared to single-arc VMAT--the decrease in MU∕Gy compared to IMRT was noticeably smaller at 12.2%-18.5%, when compared to IMRT. A hybrid VMAT∕IMRT strategy was implemented to find a high quality compromise between gantry-angle and intensity-based degrees of freedom. This optimization method will allow patients to be simultaneously planned for dosimetric quality and delivery efficiency without switching between delivery techniques. Example phantom and clinical cases suggest that the conversion of only three VMAT segments to modulated beams may result in a good combination of quality and efficiency.

[Statistical process control applied to intensity modulated radiotherapy pretreatment controls with portal dosimetry].

PubMed

Villani, N; Gérard, K; Marchesi, V; Huger, S; François, P; Noël, A

2010-06-01

The first purpose of this study was to illustrate the contribution of statistical process control for a better security in intensity modulated radiotherapy (IMRT) treatments. This improvement is possible by controlling the dose delivery process, characterized by pretreatment quality control results. So, it is necessary to put under control portal dosimetry measurements (currently, the ionisation chamber measurements were already monitored by statistical process control thanks to statistical process control tools). The second objective was to state whether it is possible to substitute ionisation chamber with portal dosimetry in order to optimize time devoted to pretreatment quality control. At Alexis-Vautrin center, pretreatment quality controls in IMRT for prostate and head and neck treatments were performed for each beam of each patient. These controls were made with an ionisation chamber, which is the reference detector for the absolute dose measurement, and with portal dosimetry for the verification of dose distribution. Statistical process control is a statistical analysis method, coming from industry, used to control and improve the studied process quality. It uses graphic tools as control maps to follow-up process, warning the operator in case of failure, and quantitative tools to evaluate the process toward its ability to respect guidelines: this is the capability study. The study was performed on 450 head and neck beams and on 100 prostate beams. Control charts, showing drifts, both slow and weak, and also both strong and fast, of mean and standard deviation have been established and have shown special cause introduced (manual shift of the leaf gap of the multileaf collimator). Correlation between dose measured at one point, given with the EPID and the ionisation chamber has been evaluated at more than 97% and disagreement cases between the two measurements were identified. The study allowed to demonstrate the feasibility to reduce the time devoted to pretreatment controls, by substituting the ionisation chamber's measurements with those performed with EPID, and also that a statistical process control monitoring of data brought security guarantee. 2010 Société française de radiothérapie oncologique (SFRO). Published by Elsevier SAS. All rights reserved.

Influence of jaw tracking in intensity-modulated and volumetric-modulated arc radiotherapy for head and neck cancers: a dosimetric study.

PubMed

Mani, Karthick Raj; Upadhayay, Sagar; Das, K J Maria

2017-03-01

To Study the dosimetric advantage of the Jaw tracking technique in intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT) for Head and Neck Cancers. We retrospectively selected 10 previously treated head and neck cancer patients stage (T1/T2, N1, M0) in this study. All the patients were planned for IMRT and VMAT with simultaneous integrated boost technique. IMRT and VMAT plans were performed with jaw tracking (JT) and with static jaw (SJ) technique by keeping the same constraints and priorities for a particular patient. Target conformity, dose to the critical structures and low dose volumes were recorded and analyzed for IMRT and VMAT plans with and without JT for all the patients. The conformity index average of all patients followed by standard deviation ([Formula: see text] ± [Formula: see text]) of the JT-IMRT, SJ-IMRT, JT-VMAT, and SJ-VMAT were 1.72 ± 0.56, 1.67 ± 0.57, 1.83 ± 0.65, and 1.85 ± 0.64, and homogeneity index were 0.059 ± 0.05, 0.064 ± 0.05, 0.064 ± 0.04, and 0.064 ± 0.05. JT-IMRT shows significant mean reduction in right parotid and left parotid shows of 7.64% (p < 0.001) and 7.45% (p < 0.001) compare to SJ-IMRT. JT-IMRT plans also shows considerable dose reduction to thyroid, inferior constrictors, spinal cord and brainstem compared to the SJ-IMRT plans. Significant dose reductions were observed for critical structure in the JT-IMRT compared to SJ-IMRT technique. In JT-VMAT plans dose reduction to the critical structure were not significant compared to the SJ-IMRT due to relatively lesser monitor units.

Comparing treatment plan in all locations of esophageal cancer: volumetric modulated arc therapy versus intensity-modulated radiotherapy.

PubMed

Lin, Jang-Chun; Tsai, Jo-Ting; Chang, Chih-Chieh; Jen, Yee-Min; Li, Ming-Hsien; Liu, Wei-Hsiu

2015-05-01

The aim of this study was to compare treatment plans of volumetric modulated arc therapy (VMAT) with intensity-modulated radiotherapy (IMRT) for all esophageal cancer (EC) tumor locations.This retrospective study from July 2009 to June 2014 included 20 patients with EC who received definitive concurrent chemoradiotherapy with radiation doses >50.4 Gy. Version 9.2 of Pinnacle with SmartArc was used for treatment planning. Dosimetric quality was evaluated based on doses to several organs at risk, including the spinal cord, heart, and lung, over the same coverage of gross tumor volume.In upper thoracic EC, the IMRT treatment plan had a lower lung mean dose (P = 0.0126) and lung V5 (P = 0.0037) compared with VMAT; both techniques had similar coverage of the planning target volumes (PTVs) (P = 0.3575). In middle thoracic EC, a lower lung mean dose (P = 0.0010) and V5 (P = 0.0145), but higher lung V20 (P = 0.0034), spinal cord Dmax (P = 0.0262), and heart mean dose (P = 0.0054), were observed for IMRT compared with VMAT; IMRT provided better PTV coverage. Patients with lower thoracic ECs had a lower lung mean dose (P = 0.0469) and V5 (P = 0.0039), but higher spinal cord Dmax (P = 0.0301) and heart mean dose (P = 0.0020), with IMRT compared with VMAT. PTV coverage was similar (P = 0.0858) for the 2 techniques.IMRT provided a lower mean dose and lung V5 in upper thoracic EC compared with VMAT, but exhibited different advantages and disadvantages in patients with middle or lower thoracic ECs. Thus, choosing different techniques for different EC locations is warranted.

A comparison of volumetric modulated arc therapy and sliding-window intensity-modulated radiotherapy in the treatment of Stage I-II nasal natural killer/T-cell lymphoma

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

Liu, Xianfeng; Yang, Yong; Jin, Fu

This article is aimed to compare the dosimetric differences between volumetric modulated arc therapy (VMAT) and intensity-modulated radiotherapy (IMRT) for Stage I-II nasal natural killer/T-cell lymphoma (NNKTL). Ten patients with Stage I-II NNKTL treated with IMRT were replanned with VMAT (2 arcs). The prescribed dose of the planning target volume (PTV) was 50 Gy in 25 fractions. The VMAT plans with the Anisotropic Analytical Algorithm (Version 8.6.15) were based on an Eclipse treatment planning system; the monitor units (MUs) and treatment time (T) were scored to measure the expected treatment efficiency. All the 10 patients under the study were subjectmore » to comparisons regarding the quality of target coverage, the efficiency of delivery, and the exposure of normal adjacent organs at risk (OARs). The study shows that VMAT was associated with a better conformal index (CI) and homogeneity index (HI) (both p < 0.05) but slightly higher dose to OARs than IMRT. The MUs with VMAT (650.80 ± 24.59) were fewer than with IMRT (1300.10 ± 57.12) (relative reduction of 49.94%, p = 0.00) when using 2-Gy dose fractions. The treatment time with VMAT (3.20 ± 0.02 minutes) was shorter than with IMRT (7.38 ± 0.18 minutes) (relative reduction of 56.64%, p = 0.00). We found that VMAT and IMRT both provide satisfactory target dosimetric coverage and OARs sparing clinically. Likely to deliver a bit higher dose to OARs, VMAT in comparison with IMRT, is still a better choice for treatment of patients with Stage I-II NNKTL, thanks to better dose distribution, fewer MUs, and shorter delivery time.« less

SU-E-T-621: Planning Methodologies for Cancer of the Anal Canal: Comparing IMRT, Rapid Arc, and Pencil Beam Scanning Proton Beam

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

McGlade, J; Kassaee, A

2015-06-15

Purpose: To evaluate planning methods for anal canal cancer and compare the results of 9-field Intensity Modulated Radiotherapy (IMRT), Volumetric Modulated Arc Therapy (Varian, RapidArc), and Proton Pencil Beam Scanning (PBS). Methods: We generated plans with IMRT, RapidArc (RA) and PBS for twenty patients for both initial phase including nodes and cone down phase of treatment using Eclipe (Varian). We evaluated the advantage of each technique for each phase. RA plans used 2 to 4 arcs and various collimator orientations. PBS used two posterior oblique fields. We evaluated the plans comparing dose volume histogram (DVH), locations of hot spots, andmore » PTV dose conformity. Results: Due to complex shape of target, for RA plans, multiple arcs (>2) are required to achieve optimal PTV conformity. When the PTV exceeds 15 cm in the superior-inferior direction, limitations of deliverability start to dominate. The PTV should be divided into a superior and an inferior structure. The optimization is performed with fixed jaws for each structure and collimator set to 90 degrees for the inferior PTV. Proton PBS plans show little advantage in small bowel sparing when treating the nodes. However, PBS plan reduces volumetric dose to the bladder at the cost of higher doses to the perineal skin. IMRT plans provide good target conformity, but they generate hot spots outside of the target volume. Conclusion: When using one planning technique for entire course of treatment, Multiple arc (>2) RA plans are better as compared to IMRT and PBS plans. When combining techniques, RA for the initial phase in combination with PBS for the cone down phase results in the most optimal plans.« less

Evaluation of radiotherapy techniques for radical treatment of lateralised oropharyngeal cancers : Dosimetry and NTCP.

PubMed

McQuaid, D; Dunlop, A; Nill, S; Franzese, C; Nutting, C M; Harrington, K J; Newbold, K L; Bhide, S A

2016-08-01

The aim of this study was to investigate potential advantages and disadvantages of three-dimensional conformal radiotherapy (3DCRT), multiple fixed-field intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT) in terms of dose to the planning target volume (PTV), organs at risk (OARs) and normal tissue complication probability (NTCP) for delivering ipsilateral radiotherapy. 3DCRT, IMRT and VMAT were compared in patients with well-lateralised primary tonsillar cancers who underwent primary radical ipsilateral radiotherapy. The following parameters were compared: conformity index (CI); homogeneity index (HI); dose-volume histograms (DVHs) of PTVs and OARs; NTCP, risk of radiation-induced cancer and dose accumulation during treatment. IMRT and VMAT were superior to 3DCRT in terms of CI, HI and dose to the target volumes, as well as mandible and dose accumulation robustness. The techniques were equivalent in terms of dose and NTCP for the contralateral oral cavity, contralateral submandibular gland and mandible, when specific dose constraint objectives were used on the oral cavity volume. Although the volume of normal tissue exposed to low-dose radiation was significantly higher with IMRT and VMAT, the risk of radiation-induced secondary malignancy was dependant on the mathematical model used. This study demonstrates the superiority of IMRT/VMAT techniques over 3DCRT in terms of dose homogeneity, conformity and consistent dose delivery to the PTV throughout the course of treatment in patients with lateralised oropharyngeal cancers. Dosimetry and NTCP calculations show that these techniques are equivalent to 3DCRT with regard to the risk of acute mucositis when specific dose constraint objectives were used on the contralateral oral cavity OAR.

Dosimetric and toxicity comparison between prone and supine position IMRT for endometrial cancer

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

Beriwal, Sushil; Jain, Sheena K.; Heron, Dwight E.

2007-02-01

Purpose: To determine the dosimetric and toxicity differences between prone and supine position intensity-modulate radiotherapy in endometrial cancer patients treated with adjuvant radiotherapy. Methods: Forty-seven consecutive endometrial cancer patients treated with adjuvant RT were analyzed. Of these, 21 were treated in prone position and 26 in the supine position. Dose-volume histograms for normal tissue structures and targets were compared between the two groups. Acute and chronic toxicity were also compared between the cohorts. Results: The percentage of volume receiving 10, 20, 30, 40, 45, and 50 Gy for small bowel was 89.5%, 69%, 33%, 12.2%, 5%, and 0% in themore » prone group and 87.5%, 62.7%, 26.4%, 8%, 4.3%, and 0% in the supine group, respectively. The difference was not statistically significant. The dose-volume histograms for bladder and rectum were also comparable, except for a slightly greater percentage of volume receiving 10 Gy (1.5%) and 20 Gy (5%) for the rectum in the prone group. Acute small bowel toxicities were Grade 1 in 7 patients and Grade 2 in 14 patients in the prone group vs. Grade 1 in 6 patients and Grade 2 in 19 patients in the supine group. Chronic toxicity was Grade 1 in 7 patients and Grade 3 in 1 patient in the prone group and Grade 1 in 5 patients in the supine group. Conclusion: These preliminary results suggest that no difference exists in the dose to the normal tissue and toxicity between prone and supine intensity-modulated radiotherapy for endometrial cancer. Longer follow-up and more outcome studies are needed to determine whether any differences exist between the two approaches.« less

Toxicity Assessment of Pelvic Intensity-Modulated Radiotherapy With Hypofractionated Simultaneous Integrated Boost to Prostate for Intermediate- and High-Risk Prostate Cancer

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

McCammon, Robert; Rusthoven, Kyle E.; Kavanagh, Brian

Purpose: To evaluate the toxicity of pelvic intensity-modulated radiotherapy (IMRT) with hypofractionated simultaneous integrated boost (SIB) to the prostate for patients with intermediate- to high-risk prostate cancer. Methods and Materials: A retrospective toxicity analysis was performed in 30 consecutive patients treated definitively with pelvic SIB-IMRT, all of whom also received androgen suppression. The IMRT plans were designed to deliver 70 Gy in 28 fractions (2.5 Gy/fraction) to the prostate while simultaneously delivering 50.4 Gy in 28 fractions (1.8 Gy/fraction) to the pelvic lymph nodes. The National Cancer Institute Common Terminology Criteria for Adverse Events, version 3.0, was used to scoremore » toxicity. Results: The most common acute Grade 2 events were cystitis (36.7%) and urinary frequency/urgency (26.7%). At a median follow-up of 24 months, late toxicity exceeding Grade 2 in severity was uncommon, with two Grade 3 events and one Grade 4 event. Grade 2 or greater acute bowel toxicity was associated with signficantly greater bowel volume receiving {>=}25 Gy (p = .04); Grade 2 or greater late bowel toxicity was associated with a higher bowel maximal dose (p = .04) and volume receiving {>=}50 Gy (p = .02). Acute or late bladder and rectal toxicity did not correlate with any of the dosimetric parameters examined. Conclusion: Pelvic IMRT with SIB to the prostate was well tolerated in this series, with low rates of Grade 3 or greater acute and late toxicity. SIB-IMRT combines pelvic radiotherapy and hypofractionation to the primary site and offers an accelerated approach to treating intermediate- to high-risk disease. Additional follow-up is necessary to fully define the long-term toxicity after hypofractionated, whole pelvic treatment combined with androgen suppression.« less

Improved Dosimetric and Clinical Outcomes With Intensity-Modulated Radiotherapy for Head-and-Neck Cancer of Unknown Primary Origin

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

Chen, Allen M., E-mail: allen.chen@ucdmc.ucdavis.ed; Li Baoqing; Farwell, D. Gregory

2011-03-01

Purpose: To compare differences in dosimetric, clinical, and quality-of-life endpoints among a cohort of patients treated by intensity-modulated radiotherapy (IMRT) and conventional radiotherapy (CRT) for head-and-neck cancer of unknown primary origin. Methods and Materials: The medical records of 51 patients treated by radiation therapy for squamous cell carcinoma of the head and neck presenting as cervical lymph node metastasis of occult primary origin were reviewed. Twenty-four patients (47%) were treated using CRT, and 27 (53%) were treated using IMRT. The proportions of patients receiving concurrent chemotherapy were 54% and 63%, respectively. Results: The 2-year estimates of overall survival, local-regional control,more » and disease-specific survival for the entire patient population were 86%, 89%, and84%, respectively. There were no significant differences in any of these endpoints with respect to radiation therapy technique (p > 0.05 for all). Dosimetric analysis revealed that the use of IMRT resulted in significant improvements with respect to mean dose and V30 to the contralateral (spared) parotid gland. In addition, mean doses to the ipsilateral inner and middle ear structures were significantly reduced with IMRT (p < 0.05 for all). The incidence of severe xerostomia in the late setting was 58% and 11% among patients treated by CRT and IMRT, respectively (p < 0.001). The percentages of patients who were G-tube dependent at 6 months after treatment were 42% and 11%, respectively (p < 0.001). Conclusions: IMRT results in significant improvements in the therapeutic ratio among patients treated by radiation therapy for head-and-neck cancer of unknown primary origin.« less

Patient-reported outcomes following parotid-sparing intensity-modulated radiotherapy for head and neck cancer. How important is dysphagia?

PubMed

Roe, Justin W G; Drinnan, Michael J; Carding, Paul N; Harrington, Kevin J; Nutting, Christopher M

2014-12-01

Swallowing can be significantly affected during and following radiotherapy for head and neck cancer (HNC). The purpose of this study was to understand: (1) the trajectory of swallowing recovery following parotid-sparing intensity-modulated radiotherapy (IMRT) and (2) overall physical and social-emotional wellbeing and how patients prioritise swallowing following treatment. Sixty-one HNC patients completed questionnaires as part of a prospective study exploring patient-reported swallowing outcomes following parotid-sparing IMRT. Participants were asked to complete the M.D. Anderson Dysphagia Inventory (MDADI) and University of Washington Quality of Life Questionnaire (UW-QoL) v.04 before treatment and 3, 6 and 12months after treatment. Given the rise in human papilloma virus (HPV) and associated oropharyngeal cancers, we completed a sub analysis of the data in those participants. There was a significant reduction in the MDADI composite scores 3months after completion of treatment. Improvements were observed by 12months, however, scores did not recover to baseline. The recovery in physical function was limited in comparison to social-emotional recovery at 12months. When oropharyngeal cancer scores were analysed, there was not a substantial difference to the whole group results. There was a shift in priorities following treatment. Swallowing was highlighted as a concern by 44% of HNC patients up to 12months after treatment with swallowing-related factors (saliva, taste and chewing) rated highly. Patient reported swallowing outcomes were significantly affected from baseline to all follow-up time points and remained a priority concern at 12months following treatment. Overall social-emotional functioning does improve, suggesting that patients have the potential to adapt to their "new normal" following IMRT for HNC. Copyright © 2014 Elsevier Ltd. All rights reserved.

Analysis of Intensity-Modulated Radiation Therapy (IMRT), Proton and 3D Conformal Radiotherapy (3D-CRT) for Reducing Perioperative Cardiopulmonary Complications in Esophageal Cancer Patients.

PubMed

Ling, Ted C; Slater, Jerry M; Nookala, Prashanth; Mifflin, Rachel; Grove, Roger; Ly, Anh M; Patyal, Baldev; Slater, Jerry D; Yang, Gary Y

2014-12-05

Background. While neoadjuvant concurrent chemoradiotherapy has improved outcomes for esophageal cancer patients, surgical complication rates remain high. The most frequent perioperative complications after trimodality therapy were cardiopulmonary in nature. The radiation modality utilized can be a strong mitigating factor of perioperative complications given the location of the esophagus and its proximity to the heart and lungs. The purpose of this study is to make a dosimetric comparison of Intensity-Modulated Radiation Therapy (IMRT), proton and 3D conformal radiotherapy (3D-CRT) with regard to reducing perioperative cardiopulmonary complications in esophageal cancer patients. Materials. Ten patients with esophageal cancer treated between 2010 and 2013 were evaluated in this study. All patients were simulated with contrast-enhanced CT imaging. Separate treatment plans using proton radiotherapy, IMRT, and 3D-CRT modalities were created for each patient. Dose-volume histograms were calculated and analyzed to compare plans between the three modalities. The organs at risk (OAR) being evaluated in this study are the heart, lungs, and spinal cord. To determine statistical significance, ANOVA and two-tailed paired t-tests were performed for all data parameters. Results. The proton plans showed decreased dose to various volumes of the heart and lungs in comparison to both the IMRT and 3D-CRT plans. There was no difference between the IMRT and 3D-CRT plans in dose delivered to the lung or heart. This finding was seen consistently across the parameters analyzed in this study. Conclusions. In patients receiving radiation therapy for esophageal cancer, proton plans are technically feasible while achieving adequate coverage with lower doses delivered to the lungs and cardiac structures. This may result in decreased cardiopulmonary toxicity and less morbidity to esophageal cancer patients.

Efficacy and Toxicity of Chemoradiotherapy Using Intensity-Modulated Radiotherapy for Unknown Primary of Head and Neck

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

Sher, David J., E-mail: dsher@lroc.harvard.edu; Balboni, Tracy A.; Haddad, Robert I.

2011-08-01

Purpose: No single standard treatment paradigm is available for head-and-neck squamous cell carcinoma of an unknown primary (HNCUP). Bilateral neck radiotherapy with mucosal axis irradiation is widely used, with or without chemotherapy and/or surgical resection. Intensity-modulated radiotherapy (IMRT) is a highly conformal method for delivering radiation that is becoming the standard of care and might reduce the long-term treatment-related sequelae. We report the Dana-Farber Cancer Institute experience with IMRT-based treatment for HNCUP. Patients and Materials: A retrospective study of all patients treated at the Dana-Farber Cancer Institute for HNCUP with IMRT between August 2004 and January 2009. The primary endpointmore » was overall survival; the secondary endpoints were locoregional and distant control, and acute and chronic toxicity. Results: A total of 24 patients with HNCUP were included. Of these patients, 22 had Stage N2 disease or greater. All patients underwent neck computed tomography, positron emission tomography-computed tomography, and examination under anesthesia with directed biopsies. Of the 24 patients, 22 received concurrent chemotherapy, and 7 (29%) also underwent induction chemotherapy. The median involved nodal dose was 70 Gy, and the median mucosal dose was 60 Gy. With a median follow-up of 2.1 years, the 2-year actuarial overall survival and locoregional control rate was 92% and 100%, respectively. Only 25% of the patients had Grade 2 xerostomia, although 11 patients (46%) required esophageal dilation for stricture. Conclusion: In a single-institution series, IMRT-based chemoradiotherapy for HNCUP was associated with superb overall survival and locoregional control. The xerostomia rates were promising, but the aggressive therapy was associated with significant rates of esophageal stenosis.« less

The Influence of Changes in Tumor Hypoxia on Dose-Painting Treatment Plans Based on {sup 18}F-FMISO Positron Emission Tomography

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

Lin Zhixiong; Mechalakos, James; Nehmeh, Sadek

2008-03-15

Purpose: To evaluate how changes in tumor hypoxia, according to serial fluorine-18-labeled fluoro-misonidazole ({sup 18}F-FMISO) positron emission tomography (PET) imaging, affect the efficacy of intensity-modulated radiotherapy (IMRT) dose painting. Methods and Materials: Seven patients with head and neck cancers were imaged twice with FMISO PET, separated by 3 days, before radiotherapy. Intensity-modulated radiotherapy plans were designed, on the basis of the first FMISO scan, to deliver a boost dose of 14 Gy to the hypoxic volume, in addition to the 70-Gy prescription dose. The same plans were then applied to hypoxic volumes from the second FMISO scan, and the efficacymore » of dose painting evaluated by assessing coverage of the hypoxic volumes using D{sub max}, D{sub min}, D{sub mean}, D{sub 95}, and equivalent uniform dose (EUD). Results: Similar hypoxic volumes were observed in the serial scans for 3 patients but dissimilar ones for the other 4. There was reduced coverage of hypoxic volumes of the second FMISO scan relative to that of the first scan (e.g., the average EUD decreased from 87 Gy to 80 Gy). The decrease was dependent on the similarity of the hypoxic volumes of the two scans (e.g., the average EUD decrease was approximately 4 Gy for patients with similar hypoxic volumes and approximately 12 Gy for patients with dissimilar ones). Conclusions: The changes in spatial distribution of tumor hypoxia, as detected in serial FMISO PET imaging, compromised the coverage of hypoxic tumor volumes achievable by dose-painting IMRT. However, dose painting always increased the EUD of the hypoxic volumes.« less

Managed care and the diffusion of intensity-modulated radiotherapy for prostate cancer.

PubMed

Jacobs, Bruce L; Zhang, Yun; Skolarus, Ted A; Wei, John T; Montie, James E; Schroeck, Florian R; Hollenbeck, Brent K

2012-12-01

To better understand associations between managed care penetration in health care markets and the adoption of intensity-modulated radiotherapy (IMRT). We used Surveillance, Epidemiology, and End Results-Medicare data to identify men diagnosed with prostate cancer between 2001 and 2007 who were treated with radiotherapy (n = 55,162). We categorized managed care penetration in Health Service Areas (HSAs) as low (<3%), intermediate (3%-10%), and high (>10%), and assessed our main outcomes (ie, probability of IMRT adoption, which is the ability of a health care market to deliver IMRT, and IMRT utilization in HSA markets) using a Cox proportional hazards model and Poisson regression model, respectively. Compared with markets with low managed care penetration, populations in highly penetrated HSAs were more racially diverse (25% vs 15% non-white, P <.01), densely populated (2110 vs 145 people/square mile, P <.01), and wealthier (median income, $48,500 vs $31,900, P <.01). The probability of IMRT adoption was greatest in markets with the highest managed care penetration (eg, 0.82 [high] vs 0.72 [low] in 2007, P = .05). Among adopting markets, the use of IMRT increased in all HSA categories. However, relative to markets with low managed care penetration, IMRT use was constrained in markets with the highest penetration (0.69 [high] vs 0.76 [low] in 2007, P <.01). Markets with higher managed care penetration demonstrated a greater propensity for acquiring IMRT technology. However, after adopting IMRT, more highly penetrated markets had roughly 7% slower growth in IMRT use during the study period. These findings provide insight into the implications of delivery system reforms for cancer-related technologies. Copyright © 2012 Elsevier Inc. All rights reserved.

Image-Guided Intensity-Modulated Radiotherapy for Pancreatic Carcinoma

PubMed Central

Fuss, Martin; Wong, Adrian; Fuller, Clifton D.; Salter, Bill J.; Fuss, Cristina; Thomas, Charles R.

2007-01-01

Purpose To present the techniques and preliminary outcomes of ultrasound-based image-guided intensity-modulated radiotherapy (IG-IMRT) for pancreatic cancer. Materials and Methods Retrospective analysis of 41 patients treated between November 2000 and March 2005 with IG-IMRT to mean total doses of 55 Gy (range, 45–64 Gy). We analyzed the clinical feasibility of IG-IMRT, dosimetric parameters, and outcomes, including acute gastrointestinal toxicity (RTOG grading). Survival was assessed for adenocarcinoma (n = 35) and other histologies. Results Mean daily image-guidance corrective shifts were 4.8 ± 4.3 mm, 7.5 ± 7.2 mm, and 4.6 ± 5.9 mm along the x-, y-, and z-axes, respectively (mean 3D correction vector, 11.7 ± 8.4 mm). Acute upper gastrointestinal toxicity was grade 0–1 in 22 patients (53.7%), grade 2 in 16 patients (39%), and grade 3 in 3 patients (7.3%). Lower gastrointestinal toxicity was grade 0–1 in 32 patients (78%), grade 2 in 7 patients (17.1%), and grade 4 in 2 patients (4.9%). Treatment was stopped early in 4 patients following administration of 30 to 54 Gy. Median survival for adenocarcinoma histology was 10.3 months (18.6 months in patients alive at analysis; n = 8) with actuarial 1- and 2-year survivals of 38% and 25%, respectively. Conclusion Daily image-guidance during delivery of IMRT for pancreatic carcinoma is clinically feasible. The data presented support the conclusion that safety margin reduction and moderate dose escalation afforded by implementation of these new radiotherapy technologies yields preliminary outcomes at least comparable with published survival data. PMID:19262697

Accelerated partial breast intensity-modulated radiotherapy in women who have prior breast augmentation.

PubMed

Leonard, Charles E; Johnson, Tim; Tallhamer, Michael; Howell, Kathryn; Kercher, Jane; Kaske, Terese; Barke, Lora; Sedlacek, Scot; Hobart, Tracy; Carter, Dennis L

2011-06-01

To examine the outcome of breast cancer patients who have prior breast augmentation treated with lumpectomy followed by accelerated partial breast external intensity-modulated radiotherapy (APBIMRT) with image-guided radiotherapy (IGRT). Four patients with previous elective subpectoral breast augmentation were enrolled on this APBIMRT trial. These four patients were treated with 10 equal twice daily 3.85 Gy fractions over 5 consecutive days (total dose of 38.5 Gy) using APBIMRT and IGRT. Patients were assessed for pain and cosmetic outcome (physician and a patient self-assessment). At last follow-up, two patients reported an excellent cosmetic results (at 2 years and at 8 months, respectively), one reported good cosmetic results (at 2 years), and one reported poor cosmetic results (at 20 months). Physicians rated the cosmetic outcomes as excellent in two (CEL; at 2 years and 8 months, respectively), good in one (CEL; at 20 months) and excellent in one (KTH; at 2 years). Three patients reported no breast/chest wall pain (two at 2 years and one at 1 year) and the fourth reported mild pain (at 20 months). The mean percent volume of ipsilateral breast receiving 100%, 75%, 50%, and 25% of the prescribed dose was 7.28%, 17.55%, 24.33%, and 33.1%, respectively. The mean breast, planning target volume (PTV), and implant volumes were 399.88 cc, 43.55 cc, and 313.36 cc, respectively. The mean breast prosthesis/total volume (breast tissue plus prosthesis) ratio was 44.55%. The mean PTV/ipsilateral breast and PTV/total volume ratios were 11.1% and 6.1%, respectively. The results show that a regimen of APBIMRT with IGRT is possible in patients who have prior breast augmentation. Copyright © 2011 Elsevier Inc. All rights reserved.

Retrospective estimate of the quality of intensity-modulated radiotherapy plans for lung cancer

NASA Astrophysics Data System (ADS)

Koo, Jihye; Yoon, Myonggeun; Chung, Weon Kuu; Kim, Dong Wook

2015-07-01

This study estimated the planning quality of intensity-modulated radiotherapy in 42 lung cancer cases to provide preliminary data for the development of a planning quality assurance algorithm. Organs in or near the thoracic cavity (ipsilateral lung, contralateral lung, heart, liver, esophagus, spinal cord, and bronchus) were selected as organs at risk (OARs). Radiotherapy plans were compared by using the conformity index (CI), coverage index (CVI), and homogeneity index (HI) of the planning target volume (PTV), the OAR-PTV distance and the OAR-PTV overlap volume, and the V10 Gy , V20 Gy , and equivalent uniform dose (EUD) of the OARs. The CI, CVI, and HI of the PTV were 0.54-0.89 (0.77 ± 0.08), 0.90-1.00 (0.98 ± 0.02), and 0.11-0.41, (0.15 ± 0.05), respectively. The mean EUDs (V10 Gy , V20 Gy ) of the ipsilateral lung, contralateral lung, esophagus, cord, liver, heart, and bronchus were 8.07 Gy (28.06, 13.17), 2.59 Gy (6.53, 1.18), 7.02 Gy (26.17, 12.32), 3.56 Gy (13.56, 4.48), 0.72 Gy (2.15, 0.91), 5.14 Gy (19.68, 8.62), and 10.56 Gy (36.08, 19.79), respectively. EUDs tended to decrease as the OAR-PTV distance increased and the OAR-PTV overlap volume decreased. Because the plans in this study were from a single department, relatively few people were involved in treatment planning. Differences in treatment results for a given patient would be much more pronounced if many departments were involved.

Prospective study of neoadjuvant chemoradiotherapy using intensity-modulated radiotherapy and 5 fluorouracil for locally advanced rectal cancer – toxicities and response assessment

PubMed Central

Simson, David K; Mitra, Swarupa; Ahlawat, Parveen; Saxena, Upasna; Sharma, Manoj Kumar; Rawat, Sheh; Singh, Harpreet; Bansal, Babita; Sripathi, Lalitha Kameshwari; Tanwar, Aditi

2018-01-01

Aims and objectives The past 2 decades witnessed the strengthening of evidence favoring the role of neoadjuvant chemoradiation (CHRT) in the treatment of locally advanced rectal cancer. The study aims to evaluate the response and acute toxicities to neoadjuvant CHRT using intensity-modulated radiotherapy (IMRT) in the treatment of rectal cancer. Predictive factors to achieve pathological complete response (pCR) were analyzed, as a secondary endpoint. Materials and methods All consecutive patients who underwent IMRT as part of neoadjuvant CHRT in the treatment of rectal cancer between August 2014 and December 2016 at a tertiary cancer care center were accrued for the study. The cohort underwent CHRT with IMRT technique at a dose of 50.4 Gy in 28 fractions concurrent with continuous infusion of 5 fluorouracil during the first and the last 4 days of CHRT. Surgery was performed 6 weeks later and the pathological response to CHRT was noted. Results Forty-three subjects were accrued for the study. Radiation dermatitis and diarrhea were the only observed grade ≥3 acute toxicities. Sphincter preservation rate (SPR) was 43.3%. pCR was observed in 32.6%. Univariate and multivariate logistic regression showed that carcinoembryonic antigen was the only independent predictive factor to achieve pCR. Conclusion IMRT as part of neoadjuvant CHRT in the treatment of locally advanced rectal cancer is well tolerated and gives comparable results with respect to earlier studies in terms of pathological response and SPR. Further randomized controlled studies are needed to firmly state that IMRT is superior to 3-dimensional conformal radiotherapy. PMID:29593430

Technology diffusion and diagnostic testing for prostate cancer.

PubMed

Schroeck, Florian R; Kaufman, Samuel R; Jacobs, Bruce L; Skolarus, Ted A; Miller, David C; Weizer, Alon Z; Montgomery, Jeffrey S; Wei, John T; Shahinian, Vahakn B; Hollenbeck, Brent K

2013-11-01

While the dissemination of robotic prostatectomy and intensity modulated radiotherapy may fuel the increased use of prostatectomy and radiotherapy, these new technologies may also have spillover effects related to diagnostic testing for prostate cancer. Therefore, we examined the association of regional technology penetration with the receipt of prostate specific antigen testing and prostate biopsy. In this retrospective cohort study we included 117,857 men 66 years old or older from the 5% sample of Medicare beneficiaries living in Surveillance, Epidemiology and End Results (SEER) areas from 2003 to 2007. Regional technology penetration was measured as the number of providers performing robotic prostatectomy or intensity modulated radiotherapy per population in a health care market, ie hospital referral region. We assessed the association of technology penetration with the prostate specific antigen testing rate and prostate biopsy using generalized estimating equations. High technology penetration was associated with an increased rate of prostate specific antigen testing (442 vs 425/1,000 person-years, p<0.01) and a similar rate of prostate biopsy (10.1 vs 9.9/1,000 person-years, p=0.69). The impact of technology penetration on prostate specific antigen testing and prostate biopsy was much less than the effect of age, race and comorbidity, eg the prostate specific antigen testing rate per 1,000 person-years was 485 vs 373 for men with only 1 vs 3+ comorbid conditions (p<0.01). Increased technology penetration is associated with a slightly higher rate of prostate specific antigen testing and no change in the prostate biopsy rate. Collectively, our findings temper concerns that adopting new technology accelerates diagnostic testing for prostate cancer. Copyright © 2013 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

Analysis of Intensity-Modulated Radiation Therapy (IMRT), Proton and 3D Conformal Radiotherapy (3D-CRT) for Reducing Perioperative Cardiopulmonary Complications in Esophageal Cancer Patients

PubMed Central

Ling, Ted C.; Slater, Jerry M.; Nookala, Prashanth; Mifflin, Rachel; Grove, Roger; Ly, Anh M.; Patyal, Baldev; Slater, Jerry D.; Yang, Gary Y.

2014-01-01

Background. While neoadjuvant concurrent chemoradiotherapy has improved outcomes for esophageal cancer patients, surgical complication rates remain high. The most frequent perioperative complications after trimodality therapy were cardiopulmonary in nature. The radiation modality utilized can be a strong mitigating factor of perioperative complications given the location of the esophagus and its proximity to the heart and lungs. The purpose of this study is to make a dosimetric comparison of Intensity-Modulated Radiation Therapy (IMRT), proton and 3D conformal radiotherapy (3D-CRT) with regard to reducing perioperative cardiopulmonary complications in esophageal cancer patients. Materials. Ten patients with esophageal cancer treated between 2010 and 2013 were evaluated in this study. All patients were simulated with contrast-enhanced CT imaging. Separate treatment plans using proton radiotherapy, IMRT, and 3D-CRT modalities were created for each patient. Dose-volume histograms were calculated and analyzed to compare plans between the three modalities. The organs at risk (OAR) being evaluated in this study are the heart, lungs, and spinal cord. To determine statistical significance, ANOVA and two-tailed paired t-tests were performed for all data parameters. Results. The proton plans showed decreased dose to various volumes of the heart and lungs in comparison to both the IMRT and 3D-CRT plans. There was no difference between the IMRT and 3D-CRT plans in dose delivered to the lung or heart. This finding was seen consistently across the parameters analyzed in this study. Conclusions. In patients receiving radiation therapy for esophageal cancer, proton plans are technically feasible while achieving adequate coverage with lower doses delivered to the lungs and cardiac structures. This may result in decreased cardiopulmonary toxicity and less morbidity to esophageal cancer patients. PMID:25489937

[Feasibility and short-term efficacy of simplified intensity-modulated radiotherapy and concurrent chemotherapy for neck and upper thoracic esophageal carcinoma].

PubMed

Zhu, Wei-Guo; Yu, Chang-Hua; Han, Ji-Hua; Li, Tao; Zhou, Xi-Lei; Tao, Guang-Zhou

2009-12-01

For neck and upper thoracic esophageal carcinoma, three dimensional conformal radiation therapy (3D-CRT) does not necessarily meet all clinical requirements while intensity modulated radiation therapy (IMRT) may take up a lot of labour power and material resources. This study was to explore the feasibility of simplified IMPT(sIMRT) and concurrent chemotherapy for neck and upper thoracic esophageal carcinoma, and to investigate the acute toxicities and short-term efficacy of this treatment modality. sIMRT plans were designed for 30 patients with neck and upper thoracic esophageal carcinoma. Two target volumes were defined: PTV1, which was designed to irradiate to 64 Gy (2.13 Gy x 30 fractions); PTV2, which was given to 54 Gy (1.8 Gy x 30). The sIMRT plan included five equiangular coplanar beams. All patients concurrently received DDP+5-FU regimen with radiotherapy on d1-5 and d29-33. Chemotherapy was repeated for two cycles 28 days after radiotherapy. The treatment was completed for all patients within 6 weeks, and only one patient had Grade 3 acute bronchitis. The complete response (CR) rate was 90.0% (27/30) and the partial response (PR) rate 10.0% (3/30). Overall response was 100% for esophageal lesions and the CR rate 76.5% (13/17). The PR rate was 23.5% (4/17) in lymph node lesions. The major toxicities observed were Grades I-II leukocytopenia. sIMRT can generate desirable dose distribution for neck and upper thoracic esophageal carcinoma, which is similar to sophisticated IMRT but obviously better than 3D-CRT. The short-term efficacy of sIMRT is satisfactory and its acute toxicities are tolerable.

Effect of Intensity-Modulated Pelvic Radiotherapy on Second Cancer Risk in the Postoperative Treatment of Endometrial and Cervical Cancer

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

Zwahlen, Daniel R.; Department of Radiation Oncology, University Hospital Zurich, Zurich; Ruben, Jeremy D.

2009-06-01

Purpose: To estimate and compare intensity-modulated radiotherapy (IMRT) with three-dimensional conformal radiotherapy (3DCRT) in terms of second cancer risk (SCR) for postoperative treatment of endometrial and cervical cancer. Methods and Materials: To estimate SCR, the organ equivalent dose concept with a linear-exponential, a plateau, and a linear dose-response model was applied to dose distributions, calculated in a planning computed tomography scan of a 68-year-old woman. Three plans were computed: four-field 18-MV 3DCRT and nine-field IMRT with 6- and 18-MV photons. SCR was estimated as a function of target dose (50.4 Gy/28 fractions) in organs of interest according to the Internationalmore » Commission on Radiological Protection Results: Cumulative SCR relative to 3DCRT was +6% (3% for a plateau model, -4% for a linear model) for 6-MV IMRT and +26% (25%, 4%) for the 18-MV IMRT plan. For an organ within the primary beam, SCR was +12% (0%, -12%) for 6-MV and +5% (-2%, -7%) for 18-MV IMRT. 18-MV IMRT increased SCR 6-7 times for organs away from the primary beam relative to 3DCRT and 6-MV IMRT. Skin SCR increased by 22-37% for 6-MV and 50-69% for 18-MV IMRT inasmuch as a larger volume of skin was exposed. Conclusion: Cancer risk after IMRT for cervical and endometrial cancer is dependent on treatment energy. 6-MV pelvic IMRT represents a safe alternative with respect to SCR relative to 3DCRT, independently of the dose-response model. 18-MV IMRT produces second neutrons that modestly increase the SCR.« less

Total Mucosal Irradiation with Intensity-modulated Radiotherapy in Patients with Head and Neck Carcinoma of Unknown Primary: A Pooled Analysis of Two Prospective Studies.

PubMed

Richards, T M; Bhide, S A; Miah, A B; Del Rosario, L; Bodla, S; Thway, K; Gujral, D M; Rooney, K P; Schick, U; McGovern, T; Grove, L; Newbold, K L; Harrington, K J; Nutting, C M

2016-09-01

To determine the clinical outcomes of an intensity-modulated radiotherapy technique for total mucosal irradiation (TM-IMRT) in patients with head and neck carcinoma of unknown primary (HNCUP). A single-centre prospective phase II trial design was used in two sequential studies to evaluate TM-IMRT for HNCUP. Patients were investigated for primary tumour site using examination under anaesthetic and biopsies, computed tomography ± magnetic resonance imaging (MRI) or 18-fluorodeoxyglucose positron emission tomography-computed tomography (PET-CT). Patients received IMRT to the potential primary tumour sites and elective cervical nodes. Concomitant chemotherapy was used in patients who received primary radiotherapy or those with nodal extracapsular extension. Thirty-six patients with HNCUP were recruited; 72% male. Twenty-five patients (69.4%) had p16-positive disease. Two year mucosal and local nodal control rates were 97.1% (95% confidence interval 91.4-100) and 89.8% (78.4-100), respectively. One mucosal primary was detected 7.3 months after TM-IMRT and three patients died from recurrent/metastatic squamous cell carcinoma of the head and neck. Twelve patients (33%) developed grade 3 (Late Effects in Normal Tissue-Subjective, Objective, Management and Analytical; LENT-SOMA) dysphagia with a 1 year enteric tube feeding rate of 2.7%. The high-grade subjective xerostomia rate (LENT-SOMA) at 24 months after IMRT was 15%. At a median follow-up of 36.1 months, the use of TM-IMRT was associated with good local control. Toxicity was comparable with previously reported TM-IMRT regimens encompassing similar mucosal volumes. Copyright © 2016 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

Prophylactic lower para-aortic irradiation using intensity-modulated radiotherapy mitigates the risk of para-aortic recurrence in locally advanced cervical cancer: A 10-year institutional experience.

PubMed

Lee, Jie; Lin, Jhen-Bin; Chang, Chih-Long; Jan, Ya-Ting; Sun, Fang-Ju; Wu, Meng-Hao; Chen, Yu-Jen

2017-07-01

To evaluate the effects of prophylactic sub-renal vein radiotherapy (SRVRT) using intensity-modulated radiotherapy (IMRT) for cervical cancer. A total of 206 patients with FIGO stage IB2-IVA cervical cancer and negative para-aortic lymph nodes (PALNs) who underwent pelvic IMRT (PRT) or SRVRT between 2004 and 2013 at our institution were reviewed. SRVRT cranially extended the PRT field for PALNs up to the left renal vein level. The prescribed dose was consistent 50.4Gy in 28 fractions. Overall, 110 and 96 patients underwent PRT and SRVRT, respectively. The SRVRT group had more advanced disease based on FIGO stage and positive pelvic lymph nodes (PLNs). The median follow-up time was 60months (range, 7-143). For the total study population, the 5-year PALN recurrence-free survival (PARFS) and overall survival (OS) for PRT vs. SRVRT were 87.6% vs. 97.9% (p=0.03) and 74.5% vs. 87.8% (p=0.04), respectively. In patients with FIGO III-IVA or positive PLNs, the 5-year PARFS and OS for PRT vs. SRVRT were 80.1% vs. 96.4% (p=0.02) and 58.1% vs. 83.5% (p=0.012), respectively. However, there were no significant differences in these outcomes for patients with FIGO IB-IIB and negative PLNs. In a multivariate analysis, only SRVRT was associated with better PARFS (HR, 0.21; 95% CI, 0.06-0.78; p=0.02). The SRVRT did not significantly increase severe late toxicities. Prophylactic SRVRT using IMRT reduced PALN recurrence with tolerable toxicities, supporting the application of risk-based radiation fields for cervical cancer. Copyright © 2017 Elsevier Inc. All rights reserved.

Corrigendum to "Long-term results of a phase II study of gemcitabine and cisplatin chemotherapy combined with intensity-modulated radiotherapy in locoregionally advanced nasopharyngeal carcinoma" [Oral Oncol. 73 (2017) 118-123].

PubMed

Wu, Mingyao; Ou, Dan; He, Xiayun; Hu, Chaosu

2017-11-01

To evaluate long-term results of a phase II study of induction and adjuvant gemcitabine and cisplatin (GP) chemotherapy with intensity-modulated radiotherapy (IMRT) in locoregionally advanced nasopharyngeal carcinoma (NPC). One hundred and twelve patients (Stage III: 65, IVA-B: 47) with locoregionally advanced NPC were enrolled in this study. All patients received induction chemotherapy consisting of 1000 mg/m 2 gemcitabine on day 1 and 8, and cisplatin 25 mg/m 2 on day 1-3, every 3 weeks for 2 cycles. Adjuvant chemotherapy for 2 cycles of the same regime was given 28 days after the end of IMRT. The IMRT technique was utilized for all patients. In total, 97.3% patients completed 2 cycles of induction chemotherapy. The overall response rate (RR) of cervical lymph nodes was 89.0%. Acute toxicities were mainly grade 1-2 myleosuppression and vomiting. And 83.9% patients completed 2 cycles of adjuvant chemotherapy. All patients finished IMRT with RR at the end of IMRT for nasopharynx, lymph nodes of neck and retropharyngeal area being 99.1%, 97.9% and 97.7%, respectively. The 5-year local control, regional control, distant metastasis-free and overall survival rates were 93.2%, 92.3%, 89.0% and 82.1%, respectively. The 5-year overall survival of stage III and IVA-B were 87.0%, and 75.5%, respectively. The incidence of grade 3-4 acute radiotherapy-related mucositis was 28.6%. Severe late toxicities were uncommon. IMRT combined with GP for locoregionally advanced NPC is well tolerated, effective, and convenient, and warrants further studies. Copyright © 2017 Elsevier Ltd. All rights reserved.

Volumetric modulation arc radiotherapy with flattening filter-free beams compared with static gantry IMRT and 3D conformal radiotherapy for advanced esophageal cancer: a feasibility study.

PubMed

Nicolini, Giorgia; Ghosh-Laskar, Sarbani; Shrivastava, Shyam Kishore; Banerjee, Sushovan; Chaudhary, Suresh; Agarwal, Jai Prakash; Munshi, Anusheel; Clivio, Alessandro; Fogliata, Antonella; Mancosu, Pietro; Vanetti, Eugenio; Cozzi, Luca

2012-10-01

A feasibility study was performed to evaluate RapidArc (RA), and the potential benefit of flattening filter-free beams, on advanced esophageal cancer against intensity-modulated radiotherapy (IMRT) and three-dimensional conformal radiotherapy (3D-CRT). The plans for 3D-CRT and IMRT with three to seven and five to seven fixed beams were compared against double-modulated arcs with avoidance sectors to spare the lungs for 10 patients. All plans were optimized for 6-MV photon beams. The RA plans were studied for conventional and flattening filter-free (FFF) beams. The objectives for the planning target volume were the volume receiving ≥ 95% or at most 107% of the prescribed dose of <1% with a dose prescription of 59.4 Gy. For the organs at risk, the lung volume (minus the planning target volume) receiving ≥ 5 Gy was <60%, that receiving 20 Gy was <20%-30%, and the mean lung dose was <15.0 Gy. The heart volume receiving 45 Gy was <20%, volume receiving 30 Gy was <50%. The spinal dose received by 1% was <45 Gy. The technical delivery parameters for RA were assessed to compare the normal and FFF beam characteristics. RA and IMRT provided equivalent coverage and homogeneity, slightly superior to 3D-CRT. The conformity index was 1.2 ± 0.1 for RA and IMRT and 1.5 ± 0.2 for 3D-CRT. The mean lung dose was 12.2 ± 4.5 for IMRT, 11.3 ± 4.6 for RA, and 10.8 ± 4.4 for RA with FFF beams, 18.2 ± 8.5 for 3D-CRT. The percentage of volume receiving ≥ 20 Gy ranged from 23.6% ± 9.1% to 21.1% ± 9.7% for IMRT and RA (FFF beams) and 39.2% ± 17.0% for 3D-CRT. The heart and spine objectives were met by all techniques. The monitor units for IMRT and RA were 457 ± 139, 322 ± 20, and 387 ± 40, respectively. RA with FFF beams showed, compared with RA with normal beams, a ∼20% increase in monitor units per Gray, a 90% increase in the average dose rate, and 20% reduction in beam on time (owing to different gantry speeds). RA demonstrated, compared with conventional IMRT, a similar target coverage and some better dose sparing to the organs at risk; the advantage against conventional 3D-CRT was more evident. RA with FFF beams resulted in minor improvements in plan quality but with the potential for additional useful reduction in the treatment time. Copyright © 2012 Elsevier Inc. All rights reserved.

Inherent smoothness of intensity patterns for intensity modulated radiation therapy generated by simultaneous projection algorithms

NASA Astrophysics Data System (ADS)

Xiao, Ying; Michalski, Darek; Censor, Yair; Galvin, James M.

2004-07-01

The efficient delivery of intensity modulated radiation therapy (IMRT) depends on finding optimized beam intensity patterns that produce dose distributions, which meet given constraints for the tumour as well as any critical organs to be spared. Many optimization algorithms that are used for beamlet-based inverse planning are susceptible to large variations of neighbouring intensities. Accurately delivering an intensity pattern with a large number of extrema can prove impossible given the mechanical limitations of standard multileaf collimator (MLC) delivery systems. In this study, we apply Cimmino's simultaneous projection algorithm to the beamlet-based inverse planning problem, modelled mathematically as a system of linear inequalities. We show that using this method allows us to arrive at a smoother intensity pattern. Including nonlinear terms in the simultaneous projection algorithm to deal with dose-volume histogram (DVH) constraints does not compromise this property from our experimental observation. The smoothness properties are compared with those from other optimization algorithms which include simulated annealing and the gradient descent method. The simultaneous property of these algorithms is ideally suited to parallel computing technologies.

Poster - 52: Smoothing constraints in Modulated Photon Radiotherapy (XMRT) fluence map optimization

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

McGeachy, Philip; Villarreal-Barajas, Jose Eduardo

Purpose: Modulated Photon Radiotherapy (XMRT), which simultaneously optimizes photon beamlet energy (6 and 18 MV) and fluence, has recently shown dosimetric improvement in comparison to conventional IMRT. That said, the degree of smoothness of resulting fluence maps (FMs) has yet to be investigated and could impact the deliverability of XMRT. This study looks at investigating FM smoothness and imposing smoothing constraint in the fluence map optimization. Methods: Smoothing constraints were modeled in the XMRT algorithm with the sum of positive gradient (SPG) technique. XMRT solutions, with and without SPG constraints, were generated for a clinical prostate scan using standard dosimetricmore » prescriptions, constraints, and a seven coplanar beam arrangement. The smoothness, with and without SPG constraints, was assessed by looking at the absolute and relative maximum SPG scores for each fluence map. Dose volume histograms were utilized when evaluating impact on the dose distribution. Results: Imposing SPG constraints reduced the absolute and relative maximum SPG values by factors of up to 5 and 2, respectively, when compared with their non-SPG constrained counterparts. This leads to a more seamless conversion of FMS to their respective MLC sequences. This improved smoothness resulted in an increase to organ at risk (OAR) dose, however the increase is not clinically significant. Conclusions: For a clinical prostate case, there was a noticeable improvement in the smoothness of the XMRT FMs when SPG constraints were applied with a minor increase in dose to OARs. This increase in OAR dose is not clinically meaningful.« less

Optimizing a mobile robot control system using GPU acceleration

NASA Astrophysics Data System (ADS)

Tuck, Nat; McGuinness, Michael; Martin, Fred

2012-01-01

This paper describes our attempt to optimize a robot control program for the Intelligent Ground Vehicle Competition (IGVC) by running computationally intensive portions of the system on a commodity graphics processing unit (GPU). The IGVC Autonomous Challenge requires a control program that performs a number of different computationally intensive tasks ranging from computer vision to path planning. For the 2011 competition our Robot Operating System (ROS) based control system would not run comfortably on the multicore CPU on our custom robot platform. The process of profiling the ROS control program and selecting appropriate modules for porting to run on a GPU is described. A GPU-targeting compiler, Bacon, is used to speed up development and help optimize the ported modules. The impact of the ported modules on overall performance is discussed. We conclude that GPU optimization can free a significant amount of CPU resources with minimal effort for expensive user-written code, but that replacing heavily-optimized library functions is more difficult, and a much less efficient use of time.

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

NASA Astrophysics Data System (ADS)

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

2017-09-01

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

Efficiency and prognosis of whole brain irradiation combined with precise radiotherapy on triple-negative breast cancer.

PubMed

Wu, Xinhong; Luo, Bo; Wei, Shaozhong; Luo, Yan; Feng, Yaojun; Xu, Juan; Wei, Wei

2013-11-01

To investigate the treatment efficiency of whole brain irradiation combined with precise radiotherapy on triple-negative (TN) phenotype breast cancer patients with brain metastases and their survival times. A total of 112 metastatic breast cancer patients treated with whole brain irradiation and intensity modulated radiotherapy (IMRT) or 3D conformal radiotherapy (3DCRT) were analyzed. Thirty-seven patients were of TN phenotype. Objective response rates were compared. Survival times were estimated by using the Kaplan-Meier method. Log-rank test was used to compare the survival time difference between the TN and non-TN groups. Potential prognostic factors were determined by using a Cox proportional hazard regression model. The efficiency of radiotherapy treatment on TN and non-TN phenotypes was 96.2% and 97%, respectively. TN phenotype was associated with worse survival times than non-TN phenotype after radiotherapy (6.9 months vs. 17 months) (P < 0.01). On multivariate analysis, good prognosis was associated with non-TN status, lower graded prognosis assessment class, and nonexistence of active extracranial metastases. After whole brain irradiation followed by IMRT or 3DCRT treatment, TN phenotype breast cancer patients with intracranial metastasis had high objective response rates but shorter survival time. With respect to survival in breast cancer patients with intracranial metastasis, the TN phenotype represents a significant adverse prognostic factor.

Evaluation of clinical hypothyroidism risk due to irradiation of thyroid and pituitary glands in radiotherapy of nasopharyngeal cancer patients.

PubMed

Lin, Zhixiong; Wang, Xiaoyan; Xie, Wenjia; Yang, Zhining; Che, Kaijun; Wu, Vincent W C

2013-12-01

Radiation-induced thyroid dysfunction after radiotherapy for nasopharyngeal cancer (NPC) has been reported. This study investigated the radiation effects of the thyroid and pituitary glands on thyroid function after radiotherapy for NPC. Sixty-five NPC patients treated with radiotherapy were recruited. Baseline thyroid hormone levels comprising free triiodothyronine (fT3), free thyroxine (fT4) and thyroid-stimulating hormone (TSH) were taken before treatment and at 3, 6, 12 and 18 months. A seven-beam intensity-modulated radiotherapy plan was generated for each patient. Thyroid and pituitary gland dose volume histograms were generated, dividing the patients into four groups: high (>50 Gy) thyroid and pituitary doses (HTHP group); high thyroid and low pituitary doses (HTLP group); low thyroid and high pituitary doses; and low thyroid and pituitary doses. Incidence of hypothyroidism was analysed. Twenty-two (34%) and 17 patients (26%) received high mean thyroid and pituitary doses, respectively. At 18 months, 23.1% of patients manifested various types of hypothyroidism. The HTHP group showed the highest incidence (83.3%) of hypothyroidism, followed by the HTLP group (50%). NPC patients with high thyroid and pituitary gland doses carried the highest risk of abnormal thyroid physiology. The dose to the thyroid was more influential than the pituitary dose at 18 months after radiotherapy, and therefore more attention should be given to the thyroid gland in radiotherapy planning. © 2013 The Royal Australian and New Zealand College of Radiologists.

Anaplastic thyroid cancer: Clinical outcomes with conformal radiotherapy.

PubMed

Bhatia, Aarti; Rao, Archana; Ang, Kie-Kian; Garden, Adam S; Morrison, William H; Rosenthal, David I; Evans, Douglas B; Clayman, Gary; Sherman, Steven I; Schwartz, David L

2010-07-01

The aim of this study was to review institutional outcomes for anaplastic thyroid cancer treated with conformal 3-dimensional radiotherapy (3DRT) or intensity-modulated radiotherapy (IMRT). In all, 53 consecutive patients were analyzed. Thirty-one (58%) patients were irradiated with curative intent. Median radiation dose was 55 Gray (Gy; range, 4-70 Gy). Thirteen (25%) patients received IMRT to a median 60 Gy (range, 39.9-69.0 Gy). Thirty-nine (74%) patients received chemotherapy with radiation. The Kaplan-Meier estimate of overall survival (OS) at 1 year for definitively irradiated patients was 29%. Patients without distant metastases receiving >or=50 Gy had superior survival outcomes; 5 such patients had no evidence of disease at last follow-up. Use of IMRT versus 3DRT did not influence toxicity. Outcomes for anaplastic thyroid cancer treated with 3DRT or IMRT remain equivalent to historical results. Healthy patients with localized disease who tolerate full dose irradiation can potentially enjoy prolonged survival. Biologically targeted radiosensitization merits prioritized investigation. (c) 2009 Wiley Periodicals, Inc.

Relationship between Eustachian tube dysfunction and otitis media with effusion in radiotherapy patients.

PubMed

Akazawa, K; Doi, H; Ohta, S; Terada, T; Fujiwara, M; Uwa, N; Tanooka, M; Sakagami, M

2018-02-01

This study evaluated the relationship between radiation and Eustachian tube dysfunction, and examined the radiation dose required to induce otitis media with effusion. The function of 36 Eustachian tubes in 18 patients with head and neck cancer were examined sonotubometrically before, during, and 1, 2 and 3 months after, intensity-modulated radiotherapy. Patients with an increase of 5 dB or less in sound pressure level (dB) during swallowing were categorised as being in the dysfunction group. Additionally, radiation dose distributions were assessed in all Eustachian tubes using three dose-volume histogram parameters. Twenty-two of 25 normally functioning Eustachian tubes before radiotherapy (88.0 per cent) shifted to the dysfunction group after therapy. All ears that developed otitis media with effusion belonged to the dysfunction group. The radiation dose threshold evaluation revealed that ears with otitis media with effusion received significantly higher doses to the Eustachian tubes. The results indicate a relationship between radiation dose and Eustachian tube dysfunction and otitis media with effusion.

Optical dosimetry of radiotherapy beams using Cherenkov radiation: the relationship between light emission and dose.

PubMed

Glaser, Adam K; Zhang, Rongxiao; Gladstone, David J; Pogue, Brian W

2014-07-21

Recent studies have proposed that light emitted by the Cherenkov effect may be used for a number of radiation therapy dosimetry applications. There is a correlation between the captured light and expected dose under certain conditions, yet discrepancies have also been observed and a complete examination of the theoretical differences has not been done. In this study, a fundamental comparison between the Cherenkov emission and absorbed dose was explored for x-ray photons, electrons, and protons using both a theoretical and Monte Carlo-based analysis. Based on the findings of where dose correlates with Cherenkov emission, it was concluded that for x-ray photons the light emission would be optimally suited for narrow beam stereotactic radiation therapy and surgery validation studies, for verification of dynamic intensity-modulated and volumetric modulated arc therapy treatment plans in water tanks, near monoenergetic sources (e.g., Co-60 and brachy therapy sources) and also for entrance and exit surface imaging dosimetry of both narrow and broad beams. For electron use, Cherenkov emission was found to be only suitable for surface dosimetry applications. Finally, for proton dosimetry, there exists a fundamental lack of Cherenkov emission at the Bragg peak, making the technique of little use, although post-irradiation detection of light emission from radioisotopes could prove to be useful.

SU-E-T-632: Preliminary Study On Treating Nose Skin Using Energy and Intensity Modulated Electron Beams with Monte Carlo Based Dose Calculations

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

Jin, L; Eldib, A; Li, J

Purpose: Uneven nose surfaces and air cavities underneath and the use of bolus present complexity and dose uncertainty when using a single electron energy beam to plan treatments of nose skin with a pencil beam-based planning system. This work demonstrates more accurate dose calculation and more optimal planning using energy and intensity modulated electron radiotherapy (MERT) delivered with a pMLC. Methods: An in-house developed Monte Carlo (MC)-based dose calculation/optimization planning system was employed for treatment planning. Phase space data (6, 9, 12 and 15 MeV) were used as an input source for MC dose calculations for the linac. To reducemore » the scatter-caused penumbra, a short SSD (61 cm) was used. Our previous work demonstrates good agreement in percentage depth dose and off-axis dose between calculations and film measurement for various field sizes. A MERT plan was generated for treating the nose skin using a patient geometry and a dose volume histogram (DVH) was obtained. The work also shows the comparison of 2D dose distributions between a clinically used conventional single electron energy plan and the MERT plan. Results: The MERT plan resulted in improved target dose coverage as compared to the conventional plan, which demonstrated a target dose deficit at the field edge. The conventional plan showed higher dose normal tissue irradiation underneath the nose skin while the MERT plan resulted in improved conformity and thus reduces normal tissue dose. Conclusion: This preliminary work illustrates that MC-based MERT planning is a promising technique in treating nose skin, not only providing more accurate dose calculation, but also offering an improved target dose coverage and conformity. In addition, this technique may eliminate the necessity of bolus, which often produces dose delivery uncertainty due to the air gaps that may exist between the bolus and skin.« less

Incorporating deliverable monitor unit constraints into spot intensity optimization in intensity modulated proton therapy treatment planning

PubMed Central

Cao, Wenhua; Lim, Gino; Li, Xiaoqiang; Li, Yupeng; Zhu, X. Ronald; Zhang, Xiaodong

2014-01-01

The purpose of this study is to investigate the feasibility and impact of incorporating deliverable monitor unit (MU) constraints into spot intensity optimization in intensity modulated proton therapy (IMPT) treatment planning. The current treatment planning system (TPS) for IMPT disregards deliverable MU constraints in the spot intensity optimization (SIO) routine. It performs a post-processing procedure on an optimized plan to enforce deliverable MU values that are required by the spot scanning proton delivery system. This procedure can create a significant dose distribution deviation between the optimized and post-processed deliverable plans, especially when small spot spacings are used. In this study, we introduce a two-stage linear programming (LP) approach to optimize spot intensities and constrain deliverable MU values simultaneously, i.e., a deliverable spot intensity optimization (DSIO) model. Thus, the post-processing procedure is eliminated and the associated optimized plan deterioration can be avoided. Four prostate cancer cases at our institution were selected for study and two parallel opposed beam angles were planned for all cases. A quadratic programming (QP) based model without MU constraints, i.e., a conventional spot intensity optimization (CSIO) model, was also implemented to emulate the commercial TPS. Plans optimized by both the DSIO and CSIO models were evaluated for five different settings of spot spacing from 3 mm to 7 mm. For all spot spacings, the DSIO-optimized plans yielded better uniformity for the target dose coverage and critical structure sparing than did the CSIO-optimized plans. With reduced spot spacings, more significant improvements in target dose uniformity and critical structure sparing were observed in the DSIO- than in the CSIO-optimized plans. Additionally, better sparing of the rectum and bladder was achieved when reduced spacings were used for the DSIO-optimized plans. The proposed DSIO approach ensures the deliverability of optimized IMPT plans that take into account MU constraints. This eliminates the post-processing procedure required by the TPS as well as the resultant deteriorating effect on ultimate dose distributions. This approach therefore allows IMPT plans to adopt all possible spot spacings optimally. Moreover, dosimetric benefits can be achieved using smaller spot spacings. PMID:23835656

Monte Carlo evaluation of Acuros XB dose calculation Algorithm for intensity modulated radiation therapy of nasopharyngeal carcinoma

NASA Astrophysics Data System (ADS)

Yeh, Peter C. Y.; Lee, C. C.; Chao, T. C.; Tung, C. J.

2017-11-01

Intensity-modulated radiation therapy is an effective treatment modality for the nasopharyngeal carcinoma. One important aspect of this cancer treatment is the need to have an accurate dose algorithm dealing with the complex air/bone/tissue interface in the head-neck region to achieve the cure without radiation-induced toxicities. The Acuros XB algorithm explicitly solves the linear Boltzmann transport equation in voxelized volumes to account for the tissue heterogeneities such as lungs, bone, air, and soft tissues in the treatment field receiving radiotherapy. With the single beam setup in phantoms, this algorithm has already been demonstrated to achieve the comparable accuracy with Monte Carlo simulations. In the present study, five nasopharyngeal carcinoma patients treated with the intensity-modulated radiation therapy were examined for their dose distributions calculated using the Acuros XB in the planning target volume and the organ-at-risk. Corresponding results of Monte Carlo simulations were computed from the electronic portal image data and the BEAMnrc/DOSXYZnrc code. Analysis of dose distributions in terms of the clinical indices indicated that the Acuros XB was in comparable accuracy with Monte Carlo simulations and better than the anisotropic analytical algorithm for dose calculations in real patients.

Verification of intensity modulated profiles using a pixel segmented liquid-filled linear array.

PubMed

Pardo, J; Roselló, J V; Sánchez-Doblado, F; Gómez, F

2006-06-07

A liquid isooctane (C8H18) filled ionization chamber linear array developed for radiotherapy quality assurance, consisting of 128 pixels (each of them with a 1.7 mm pitch), has been used to acquire profiles of several intensity modulated fields. The results were compared with film measurements using the gamma test. The comparisons show a very good matching, even in high gradient dose regions. The volume-averaging effect of the pixels is negligible and the spatial resolution is enough to verify these regions. However, some mismatches between the detectors have been found in regions where low-energy scattered photons significantly contribute to the total dose. These differences are not very important (in fact, the measurements of both detectors are in agreement using the gamma test with tolerances of 3% and 3 mm in most of those regions), and may be associated with the film energy dependence. In addition, the linear array repeatability (0.27% one standard deviation) is much better than the film one ( approximately 3%). The good repeatability, small pixel size and high spatial resolution make the detector ideal for the real time profile verification of high gradient beam profiles like those present in intensity modulated radiation therapy and radiosurgery.

A new sparse optimization scheme for simultaneous beam angle and fluence map optimization in radiotherapy planning

NASA Astrophysics Data System (ADS)

Liu, Hongcheng; Dong, Peng; Xing, Lei

2017-08-01

{{\\ell }2,1} -minimization-based sparse optimization was employed to solve the beam angle optimization (BAO) in intensity-modulated radiation therapy (IMRT) planning. The technique approximates the exact BAO formulation with efficiently computable convex surrogates, leading to plans that are inferior to those attainable with recently proposed gradient-based greedy schemes. In this paper, we alleviate/reduce the nontrivial inconsistencies between the {{\\ell }2,1} -based formulations and the exact BAO model by proposing a new sparse optimization framework based on the most recent developments in group variable selection. We propose the incorporation of the group-folded concave penalty (gFCP) as a substitution to the {{\\ell }2,1} -minimization framework. The new formulation is then solved by a variation of an existing gradient method. The performance of the proposed scheme is evaluated by both plan quality and the computational efficiency using three IMRT cases: a coplanar prostate case, a coplanar head-and-neck case, and a noncoplanar liver case. Involved in the evaluation are two alternative schemes: the {{\\ell }2,1} -minimization approach and the gradient norm method (GNM). The gFCP-based scheme outperforms both counterpart approaches. In particular, gFCP generates better plans than those obtained using the {{\\ell }2,1} -minimization for all three cases with a comparable computation time. As compared to the GNM, the gFCP improves both the plan quality and computational efficiency. The proposed gFCP-based scheme provides a promising framework for BAO and promises to improve both planning time and plan quality.

A new sparse optimization scheme for simultaneous beam angle and fluence map optimization in radiotherapy planning.

PubMed

Liu, Hongcheng; Dong, Peng; Xing, Lei

2017-07-20

[Formula: see text]-minimization-based sparse optimization was employed to solve the beam angle optimization (BAO) in intensity-modulated radiation therapy (IMRT) planning. The technique approximates the exact BAO formulation with efficiently computable convex surrogates, leading to plans that are inferior to those attainable with recently proposed gradient-based greedy schemes. In this paper, we alleviate/reduce the nontrivial inconsistencies between the [Formula: see text]-based formulations and the exact BAO model by proposing a new sparse optimization framework based on the most recent developments in group variable selection. We propose the incorporation of the group-folded concave penalty (gFCP) as a substitution to the [Formula: see text]-minimization framework. The new formulation is then solved by a variation of an existing gradient method. The performance of the proposed scheme is evaluated by both plan quality and the computational efficiency using three IMRT cases: a coplanar prostate case, a coplanar head-and-neck case, and a noncoplanar liver case. Involved in the evaluation are two alternative schemes: the [Formula: see text]-minimization approach and the gradient norm method (GNM). The gFCP-based scheme outperforms both counterpart approaches. In particular, gFCP generates better plans than those obtained using the [Formula: see text]-minimization for all three cases with a comparable computation time. As compared to the GNM, the gFCP improves both the plan quality and computational efficiency. The proposed gFCP-based scheme provides a promising framework for BAO and promises to improve both planning time and plan quality.

On Voxel based Iso-Tumor Control Probabilty and Iso-Complication Maps for Selective Boosting and Selective Avoidance Intensity Modulated Radiotherapy.

PubMed

Kim, Yusung; Tomé, Wolfgang A

2008-01-01

Voxel based iso-Tumor Control Probability (TCP) maps and iso-Complication maps are proposed as a plan-review tool especially for functional image-guided intensity-modulated radiotherapy (IMRT) strategies such as selective boosting (dose painting) and conformal avoidance IMRT. The maps employ voxel-based phenomenological biological dose-response models for target volumes and normal organs. Two IMRT strategies for prostate cancer, namely conventional uniform IMRT delivering an EUD = 84 Gy (equivalent uniform dose) to the entire PTV and selective boosting delivering an EUD = 82 Gy to the entire PTV, are investigated, to illustrate the advantages of this approach over iso-dose maps. Conventional uniform IMRT did yield a more uniform isodose map to the entire PTV while selective boosting did result in a nonuniform isodose map. However, when employing voxel based iso-TCP maps selective boosting exhibited a more uniform tumor control probability map compared to what could be achieved using conventional uniform IMRT, which showed TCP cold spots in high-risk tumor subvolumes despite delivering a higher EUD to the entire PTV. Voxel based iso-Complication maps are presented for rectum and bladder, and their utilization for selective avoidance IMRT strategies are discussed. We believe as the need for functional image guided treatment planning grows, voxel based iso-TCP and iso-Complication maps will become an important tool to assess the integrity of such treatment plans.

Lowering whole-body radiation doses in pediatric intensity-modulated radiotherapy through the use of unflattened photon beams.

PubMed

Cashmore, Jason; Ramtohul, Mark; Ford, Dan

2011-07-15

Intensity modulated radiotherapy (IMRT) has been linked with an increased risk of secondary cancer induction due to the extra leakage radiation associated with delivery of these techniques. Removal of the flattening filter offers a simple way of reducing head leakage, and it may be possible to generate equivalent IMRT plans and to deliver these on a standard linear accelerator operating in unflattened mode. An Elekta Precise linear accelerator has been commissioned to operate in both conventional and unflattened modes (energy matched at 6 MV) and a direct comparison made between the treatment planning and delivery of pediatric intracranial treatments using both approaches. These plans have been evaluated and delivered to an anthropomorphic phantom. Plans generated in unflattened mode are clinically identical to those for conventional IMRT but can be delivered with greatly reduced leakage radiation. Measurements in an anthropomorphic phantom at clinically relevant positions including the thyroid, lung, ovaries, and testes show an average reduction in peripheral doses of 23.7%, 29.9%, 64.9%, and 70.0%, respectively, for identical plan delivery compared to conventional IMRT. IMRT delivery in unflattened mode removes an unwanted and unnecessary source of scatter from the treatment head and lowers leakage doses by up to 70%, thereby reducing the risk of radiation-induced second cancers. Removal of the flattening filter is recommended for IMRT treatments. Copyright © 2011 Elsevier Inc. All rights reserved.

Tumor Control Outcomes Following Hypofractionated and Single-Dose Stereotactic Image-Guided Intensity-Modulated Radiotherapy for Extracranial Metastases from Renal Cell Carcinoma

PubMed Central

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

2014-01-01

Purpose To report tumor local progression-free outcomes following treatment with single-dose image-guided intensity-modulated radiotherapy (SD-IGRT) and hypofractionated regimens for extracranial metastases from renal cell primary tumors. Methods and Materials Between 2004 and 2010, a total of 105 lesions from renal cell carcinomas were treated with either SD-IGRT to prescription doses of 18–24 Gy (median, 24 Gy) or hypofractionation (3 or 5 fractions) with prescription doses ranging between 20 and 30 Gy. The median follow-up was 12 months (range, 1–48 months). Results The overall 3-year actuarial local progression-free survival (LPFS) for all lesions was 44%. The 3-year LPFS for those who received high single-dose (24 Gy; n = 45), low single-dose (< 24 Gy; n = 14), and hypofractionation regimens (n = 46) were 88%, 21%, and 17%, respectively (high single dose versus low single dose, p = 0.001; high single dose versus hypofractionation, p < 0.001). Multivariate analysis revealed the following variables as significant predictors of improved LPFS: dose of 24 Gy compared with lower dose (p = 0.009), and single dose versus hypofractionation (p = 0.008). Conclusion High-dose SD-IGRT is a non-invasive procedure resulting in high probability of local tumor control for metastatic renal cell cancers, generally considered radioresistant according to classical radiobiological ranking. PMID:21596489

Radiotherapy in Prostate Cancer Patients With Pelvic Lymphocele After Surgery: Clinical and Dosimetric Data of 30 Patients.

PubMed

Jereczek-Fossa, Barbara Alicja; Colangione, Sarah Pia; Fodor, Cristiana; Russo, Stefania; Cambria, Raffaella; Zerini, Dario; Bonora, Maria; Cecconi, Agnese; Vischioni, Barbara; Vavassori, Andrea; Matei, Deliu Victor; Bottero, Danilo; Brescia, Antonio; Musi, Gennaro; Mazzoleni, Federica; Orsi, Franco; Bonomo, Guido; De Cobelli, Ottavio; Orecchia, Roberto

2015-08-01

The purpose of the study was to evaluate the feasibility of irradiation after prostatectomy in the presence of asymptomatic pelvic lymphocele. The inclusion criteria for this study were: (1) patients referred for postoperative (adjuvant or salvage) intensity modulated radiotherapy (IMRT; 66-69 Gy in 30 fractions); (2) detection of postoperative pelvic lymphocele at the simulation computed tomography [CT] scan; (3) no clinical symptoms; and (4) written informed consent. Radiotherapy toxicity and occurrence of symptoms or complications of lymphocele were analyzed. Dosimetric data (IMRT plans) and the modification of lymphocele volume during radiotherapy (cone beam CT [CBCT] scan) were evaluated. Between January 2011 and July 2013, in 30 of 308 patients (10%) treated with radiotherapy after prostatectomy, pelvic lymphocele was detected on the simulation CT. The median lymphocele volume was 47 cm(3) (range, 6-467.3 cm(3)). Lymphocele was not included in planning target volume (PTV) in 8 cases (27%). Maximum dose to lymphocele was 57 Gy (range, 5.7-73.3 Gy). Radiotherapy was well tolerated. In all but 2 patients, lymphoceles remained asymptomatic. Lymphocele drainage-because of symptom occurrence-had to be performed in 2 patients during IMRT and in one patient, 7 weeks after IMRT. CBCT at the end of IMRT showed reduction in lymphocele volume and position compared with the initial data (median reduction of 37%), more pronounced in lymphoceles included in PTV. Radiotherapy after prostatectomy in the presence of pelvic asymptomatic lymphocele is feasible with acceptable acute and late toxicity. The volume of lymphoceles decreased during radiotherapy and this phenomenon might require intermediate radiotherapy plan evaluation. Copyright © 2015 Elsevier Inc. All rights reserved.

A novel software and conceptual design of the hardware platform for intensity modulated radiation therapy

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

Nguyen, Dan; Ruan, Dan; O’Connor, Daniel

Purpose: To deliver high quality intensity modulated radiotherapy (IMRT) using a novel generalized sparse orthogonal collimators (SOCs), the authors introduce a novel direct aperture optimization (DAO) approach based on discrete rectangular representation. Methods: A total of seven patients—two glioblastoma multiforme, three head & neck (including one with three prescription doses), and two lung—were included. 20 noncoplanar beams were selected using a column generation and pricing optimization method. The SOC is a generalized conventional orthogonal collimators with N leaves in each collimator bank, where N = 1, 2, or 4. SOC degenerates to conventional jaws when N = 1. For SOC-basedmore » IMRT, rectangular aperture optimization (RAO) was performed to optimize the fluence maps using rectangular representation, producing fluence maps that can be directly converted into a set of deliverable rectangular apertures. In order to optimize the dose distribution and minimize the number of apertures used, the overall objective was formulated to incorporate an L2 penalty reflecting the difference between the prescription and the projected doses, and an L1 sparsity regularization term to encourage a low number of nonzero rectangular basis coefficients. The optimization problem was solved using the Chambolle–Pock algorithm, a first-order primal–dual algorithm. Performance of RAO was compared to conventional two-step IMRT optimization including fluence map optimization and direct stratification for multileaf collimator (MLC) segmentation (DMS) using the same number of segments. For the RAO plans, segment travel time for SOC delivery was evaluated for the N = 1, N = 2, and N = 4 SOC designs to characterize the improvement in delivery efficiency as a function of N. Results: Comparable PTV dose homogeneity and coverage were observed between the RAO and the DMS plans. The RAO plans were slightly superior to the DMS plans in sparing critical structures. On average, the maximum and mean critical organ doses were reduced by 1.94% and 1.44% of the prescription dose. The average number of delivery segments was 12.68 segments per beam for both the RAO and DMS plans. The N = 2 and N = 4 SOC designs were, on average, 1.56 and 1.80 times more efficient than the N = 1 SOC design to deliver. The mean aperture size produced by the RAO plans was 3.9 times larger than that of the DMS plans. Conclusions: The DAO and dose domain optimization approach enabled high quality IMRT plans using a low-complexity collimator setup. The dosimetric quality is comparable or slightly superior to conventional MLC-based IMRT plans using the same number of delivery segments. The SOC IMRT delivery efficiency can be significantly improved by increasing the leaf numbers, but the number is still significantly lower than the number of leaves in a typical MLC.« less

A novel software and conceptual design of the hardware platform for intensity modulated radiation therapy.

PubMed

Nguyen, Dan; Ruan, Dan; O'Connor, Daniel; Woods, Kaley; Low, Daniel A; Boucher, Salime; Sheng, Ke

2016-02-01

To deliver high quality intensity modulated radiotherapy (IMRT) using a novel generalized sparse orthogonal collimators (SOCs), the authors introduce a novel direct aperture optimization (DAO) approach based on discrete rectangular representation. A total of seven patients-two glioblastoma multiforme, three head & neck (including one with three prescription doses), and two lung-were included. 20 noncoplanar beams were selected using a column generation and pricing optimization method. The SOC is a generalized conventional orthogonal collimators with N leaves in each collimator bank, where N = 1, 2, or 4. SOC degenerates to conventional jaws when N = 1. For SOC-based IMRT, rectangular aperture optimization (RAO) was performed to optimize the fluence maps using rectangular representation, producing fluence maps that can be directly converted into a set of deliverable rectangular apertures. In order to optimize the dose distribution and minimize the number of apertures used, the overall objective was formulated to incorporate an L2 penalty reflecting the difference between the prescription and the projected doses, and an L1 sparsity regularization term to encourage a low number of nonzero rectangular basis coefficients. The optimization problem was solved using the Chambolle-Pock algorithm, a first-order primal-dual algorithm. Performance of RAO was compared to conventional two-step IMRT optimization including fluence map optimization and direct stratification for multileaf collimator (MLC) segmentation (DMS) using the same number of segments. For the RAO plans, segment travel time for SOC delivery was evaluated for the N = 1, N = 2, and N = 4 SOC designs to characterize the improvement in delivery efficiency as a function of N. Comparable PTV dose homogeneity and coverage were observed between the RAO and the DMS plans. The RAO plans were slightly superior to the DMS plans in sparing critical structures. On average, the maximum and mean critical organ doses were reduced by 1.94% and 1.44% of the prescription dose. The average number of delivery segments was 12.68 segments per beam for both the RAO and DMS plans. The N = 2 and N = 4 SOC designs were, on average, 1.56 and 1.80 times more efficient than the N = 1 SOC design to deliver. The mean aperture size produced by the RAO plans was 3.9 times larger than that of the DMS plans. The DAO and dose domain optimization approach enabled high quality IMRT plans using a low-complexity collimator setup. The dosimetric quality is comparable or slightly superior to conventional MLC-based IMRT plans using the same number of delivery segments. The SOC IMRT delivery efficiency can be significantly improved by increasing the leaf numbers, but the number is still significantly lower than the number of leaves in a typical MLC.

Comparison of the dose distribution obtained from dosimetric systems with intensity modulated radiotherapy planning system in the treatment of prostate cancer

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

Gökçe, M., E-mail: mgokce@adu.edu.tr; Uslu, D. Koçyiğit; Ertunç, C.

The aim of this study is to compare Intensity Modulated Radiation Therapy (IMRT) plan of prostate cancer patients with different dose verification systems in dosimetric aspects and to compare these systems with each other in terms of reliability, applicability and application time. Dosimetric control processes of IMRT plan of three prostate cancer patients were carried out using thermoluminescent dosimeter (TLD), ion chamber (IC) and 2D Array detector systems. The difference between the dose values obtained from the dosimetric systems and treatment planning system (TPS) were found to be about % 5. For the measured (TLD) and calculated (TPS) doses %3more » percentage differences were obtained for the points close to center while percentage differences increased at the field edges. It was found that TLD and IC measurements will increase the precision and reliability of the results of 2D Array.« less

Simultaneous optimization of photons and electrons for mixed beam radiotherapy

NASA Astrophysics Data System (ADS)

Mueller, S.; Fix, M. K.; Joosten, A.; Henzen, D.; Frei, D.; Volken, W.; Kueng, R.; Aebersold, D. M.; Stampanoni, M. F. M.; Manser, P.

2017-07-01

The aim of this work is to develop and investigate an inverse treatment planning process (TPP) for mixed beam radiotherapy (MBRT) capable of performing simultaneous optimization of photon and electron apertures. A simulated annealing based direct aperture optimization (DAO) is implemented to perform simultaneous optimization of photon and electron apertures, both shaped with the photon multileaf collimator (pMLC). Validated beam models are used as input for Monte Carlo dose calculations. Consideration of photon pMLC transmission during DAO and a weight re-optimization of the apertures after deliverable dose calculation are utilized to efficiently reduce the differences between optimized and deliverable dose distributions. The TPP for MBRT is evaluated for an academic situation with a superficial and an enlarged PTV in the depth, a left chest wall case including the internal mammary chain and a squamous cell carcinoma case. Deliverable dose distributions of MBRT plans are compared to those of modulated electron radiotherapy (MERT), photon IMRT and if available to those of clinical VMAT plans. The generated MBRT plans dosimetrically outperform the MERT, photon IMRT and VMAT plans for all investigated situations. For the clinical cases of the left chest wall and the squamous cell carcinoma, the MBRT plans cover the PTV similarly or more homogeneously than the VMAT plans, while OARs are spared considerably better with average reductions of the mean dose to parallel OARs and D 2% to serial OARs by 54% and 26%, respectively. Moreover, the low dose bath expressed as V 10% to normal tissue is substantially reduced by up to 45% compared to the VMAT plans. A TPP for MBRT including simultaneous optimization is successfully implemented and the dosimetric superiority of MBRT plans over MERT, photon IMRT and VMAT plans is demonstrated for academic and clinical situations including superficial targets with and without deep-seated part.

Simultaneous optimization of photons and electrons for mixed beam radiotherapy.

PubMed

Mueller, S; Fix, M K; Joosten, A; Henzen, D; Frei, D; Volken, W; Kueng, R; Aebersold, D M; Stampanoni, M F M; Manser, P

2017-06-26

The aim of this work is to develop and investigate an inverse treatment planning process (TPP) for mixed beam radiotherapy (MBRT) capable of performing simultaneous optimization of photon and electron apertures. A simulated annealing based direct aperture optimization (DAO) is implemented to perform simultaneous optimization of photon and electron apertures, both shaped with the photon multileaf collimator (pMLC). Validated beam models are used as input for Monte Carlo dose calculations. Consideration of photon pMLC transmission during DAO and a weight re-optimization of the apertures after deliverable dose calculation are utilized to efficiently reduce the differences between optimized and deliverable dose distributions. The TPP for MBRT is evaluated for an academic situation with a superficial and an enlarged PTV in the depth, a left chest wall case including the internal mammary chain and a squamous cell carcinoma case. Deliverable dose distributions of MBRT plans are compared to those of modulated electron radiotherapy (MERT), photon IMRT and if available to those of clinical VMAT plans. The generated MBRT plans dosimetrically outperform the MERT, photon IMRT and VMAT plans for all investigated situations. For the clinical cases of the left chest wall and the squamous cell carcinoma, the MBRT plans cover the PTV similarly or more homogeneously than the VMAT plans, while OARs are spared considerably better with average reductions of the mean dose to parallel OARs and D 2% to serial OARs by 54% and 26%, respectively. Moreover, the low dose bath expressed as V 10% to normal tissue is substantially reduced by up to 45% compared to the VMAT plans. A TPP for MBRT including simultaneous optimization is successfully implemented and the dosimetric superiority of MBRT plans over MERT, photon IMRT and VMAT plans is demonstrated for academic and clinical situations including superficial targets with and without deep-seated part.

Cost-effectiveness of modern radiotherapy techniques in locally advanced pancreatic cancer.

PubMed

Murphy, James D; Chang, Daniel T; Abelson, Jon; Daly, Megan E; Yeung, Heidi N; Nelson, Lorene M; Koong, Albert C

2012-02-15

Radiotherapy may improve the outcome of patients with pancreatic cancer but at an increased cost. In this study, the authors evaluated the cost-effectiveness of modern radiotherapy techniques in the treatment of locally advanced pancreatic cancer. A Markov decision-analytic model was constructed to compare the cost-effectiveness of 4 treatment regimens: gemcitabine alone, gemcitabine plus conventional radiotherapy, gemcitabine plus intensity-modulated radiotherapy (IMRT); and gemcitabine with stereotactic body radiotherapy (SBRT). Patients transitioned between the following 5 health states: stable disease, local progression, distant failure, local and distant failure, and death. Health utility tolls were assessed for radiotherapy and chemotherapy treatments and for radiation toxicity. SBRT increased life expectancy by 0.20 quality-adjusted life years (QALY) at an increased cost of $13,700 compared with gemcitabine alone (incremental cost-effectiveness ratio [ICER] = $69,500 per QALY). SBRT was more effective and less costly than conventional radiotherapy and IMRT. An analysis that excluded SBRT demonstrated that conventional radiotherapy had an ICER of $126,800 per QALY compared with gemcitabine alone, and IMRT had an ICER of $1,584,100 per QALY compared with conventional radiotherapy. A probabilistic sensitivity analysis demonstrated that the probability of cost-effectiveness at a willingness to pay of $50,000 per QALY was 78% for gemcitabine alone, 21% for SBRT, 1.4% for conventional radiotherapy, and 0.01% for IMRT. At a willingness to pay of $200,000 per QALY, the probability of cost-effectiveness was 73% for SBRT, 20% for conventional radiotherapy, 7% for gemcitabine alone, and 0.7% for IMRT. The current results indicated that IMRT in locally advanced pancreatic cancer exceeds what society considers cost-effective. In contrast, combining gemcitabine with SBRT increased clinical effectiveness beyond that of gemcitabine alone at a cost potentially acceptable by today's standards. Copyright © 2011 American Cancer Society.

Left-sided breast cancer irradiation using rotational and fixed-field radiotherapy

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

Qi, X. Sharon, E-mail: xqi@mednet.ucla.edu; Liu, Tian X.; Liu, Arthur K.

2014-10-01

The 3-dimensional conformal radiotherapy (3DCRT) technique is the standard for breast cancer radiotherapy. During treatment planning, not only the coverage of the planning target volume (PTV) but also the minimization of the dose to critical structures, such as the lung, heart, and contralateral breast tissue, need to be considered. Because of the complexity and variations of patient anatomy, more advanced radiotherapy techniques are sometimes desired to better meet the planning goals. In this study, we evaluated external-beam radiation treatment techniques for left breast cancer using various delivery platforms: fixed-field including TomoDirect (TD), static intensity-modulated radiotherapy (sIMRT), and rotational radiotherapy includingmore » Elekta volumetric-modulated arc therapy (VMAT) and tomotherapy helical (TH). A total of 10 patients with left-sided breast cancer who did or did not have positive lymph nodes and were previously treated with 3DCRT/sIMRT to the entire breast were selected, their treatment was planned with Monaco VMAT, TD, and TH. Dosimetric parameters including PTV coverage, organ-at-risk (OAR) sparing, dose-volume histograms, and target minimum/maximum/mean doses were evaluated. It is found that for plans providing comparable PTV coverage, the Elekta VMAT plans were generally more inhomogeneous than the TH and TD plans. For the cases with regional node involvement, the average mean doses administered to the heart were 9.2 (± 5.2) and 8.8 (± 3.0) Gy in the VMAT and TH plans compared with 11.9 (± 6.4) and 11.8 (± 9.2) Gy for the 3DCRT and TD plans, respectively, with slightly higher doses given to the contralateral lung or breast or both. On average, the total monitor units for VMAT plans are 11.6% of those TH plans. Our studies have shown that VMAT and TH plans offer certain dosimetric advantages over fixed-field IMRT plans for advanced breast cancer requiring regional nodal treatment. However, for early-stage breast cancer fixed-field radiotherapy is potentially more beneficial in terms of OAR sparing.« less

Left-sided breast cancer irradiation using rotational and fixed-field radiotherapy.

PubMed

Qi, X Sharon; Liu, Tian X; Liu, Arthur K; Newman, Francis; Rabinovitch, Rachel; Kavanagh, Brian; Hu, Y Angie

2014-01-01

The 3-dimensional conformal radiotherapy (3DCRT) technique is the standard for breast cancer radiotherapy. During treatment planning, not only the coverage of the planning target volume (PTV) but also the minimization of the dose to critical structures, such as the lung, heart, and contralateral breast tissue, need to be considered. Because of the complexity and variations of patient anatomy, more advanced radiotherapy techniques are sometimes desired to better meet the planning goals. In this study, we evaluated external-beam radiation treatment techniques for left breast cancer using various delivery platforms: fixed-field including TomoDirect (TD), static intensity-modulated radiotherapy (sIMRT), and rotational radiotherapy including Elekta volumetric-modulated arc therapy (VMAT) and tomotherapy helical (TH). A total of 10 patients with left-sided breast cancer who did or did not have positive lymph nodes and were previously treated with 3DCRT/sIMRT to the entire breast were selected, their treatment was planned with Monaco VMAT, TD, and TH. Dosimetric parameters including PTV coverage, organ-at-risk (OAR) sparing, dose-volume histograms, and target minimum/maximum/mean doses were evaluated. It is found that for plans providing comparable PTV coverage, the Elekta VMAT plans were generally more inhomogeneous than the TH and TD plans. For the cases with regional node involvement, the average mean doses administered to the heart were 9.2 (± 5.2) and 8.8 (± 3.0)Gy in the VMAT and TH plans compared with 11.9 (± 6.4) and 11.8 (± 9.2)Gy for the 3DCRT and TD plans, respectively, with slightly higher doses given to the contralateral lung or breast or both. On average, the total monitor units for VMAT plans are 11.6% of those TH plans. Our studies have shown that VMAT and TH plans offer certain dosimetric advantages over fixed-field IMRT plans for advanced breast cancer requiring regional nodal treatment. However, for early-stage breast cancer fixed-field radiotherapy is potentially more beneficial in terms of OAR sparing. Copyright © 2014 American Association of Medical Dosimetrists. Published by Elsevier Inc. All rights reserved.

GPU-based ultra-fast dose calculation using a finite size pencil beam model.

PubMed

Gu, Xuejun; Choi, Dongju; Men, Chunhua; Pan, Hubert; Majumdar, Amitava; Jiang, Steve B

2009-10-21

Online adaptive radiation therapy (ART) is an attractive concept that promises the ability to deliver an optimal treatment in response to the inter-fraction variability in patient anatomy. However, it has yet to be realized due to technical limitations. Fast dose deposit coefficient calculation is a critical component of the online planning process that is required for plan optimization of intensity-modulated radiation therapy (IMRT). Computer graphics processing units (GPUs) are well suited to provide the requisite fast performance for the data-parallel nature of dose calculation. In this work, we develop a dose calculation engine based on a finite-size pencil beam (FSPB) algorithm and a GPU parallel computing framework. The developed framework can accommodate any FSPB model. We test our implementation in the case of a water phantom and the case of a prostate cancer patient with varying beamlet and voxel sizes. All testing scenarios achieved speedup ranging from 200 to 400 times when using a NVIDIA Tesla C1060 card in comparison with a 2.27 GHz Intel Xeon CPU. The computational time for calculating dose deposition coefficients for a nine-field prostate IMRT plan with this new framework is less than 1 s. This indicates that the GPU-based FSPB algorithm is well suited for online re-planning for adaptive radiotherapy.

A study on the application of Fourier series in IMRT treatment planning.

PubMed

Almeida-Trinidad, R; Garnica-Garza, H M

2007-12-01

In intensity-modulated radiotherapy, a set of x-ray fluence profiles is iteratively adjusted until a desired absorbed dose distribution is obtained. The purpose of this article is to present a method that allows the optimization of fluence profiles based on the Fourier series decomposition of an initial approximation to the profile. The method has the advantage that a new fluence profile can be obtained in a precise and controlled way with the tuning of only two parameters, namely the phase of the sine and cosine terms of one of the Fourier components, in contrast to the point-by-point tuning of the profile. Also, because the method uses analytical functions, the resultant profiles do not exhibit numerical artifacts. A test case consisting of a mathematical phantom with a target wrapped around a critical structure is discussed to illustrate the algorithm. It is shown that the degree of conformality of the absorbed dose distribution can be tailored by varying the number of Fourier terms made available to the optimization algorithm. For the test case discussed here, it is shown that the number of Fourier terms to be modified depends on the number of radiation beams incident on the target but it is in general in the order of 10 terms.

Cancer radiotherapy based on femtosecond IR laser-beam filamentation yielding ultra-high dose rates and zero entrance dose.

PubMed

Meesat, Ridthee; Belmouaddine, Hakim; Allard, Jean-François; Tanguay-Renaud, Catherine; Lemay, Rosalie; Brastaviceanu, Tiberius; Tremblay, Luc; Paquette, Benoit; Wagner, J Richard; Jay-Gerin, Jean-Paul; Lepage, Martin; Huels, Michael A; Houde, Daniel

2012-09-18

Since the invention of cancer radiotherapy, its primary goal has been to maximize lethal radiation doses to the tumor volume while keeping the dose to surrounding healthy tissues at zero. Sadly, conventional radiation sources (γ or X rays, electrons) used for decades, including multiple or modulated beams, inevitably deposit the majority of their dose in front or behind the tumor, thus damaging healthy tissue and causing secondary cancers years after treatment. Even the most recent pioneering advances in costly proton or carbon ion therapies can not completely avoid dose buildup in front of the tumor volume. Here we show that this ultimate goal of radiotherapy is yet within our reach: Using intense ultra-short infrared laser pulses we can now deposit a very large energy dose at unprecedented microscopic dose rates (up to 10(11) Gy/s) deep inside an adjustable, well-controlled macroscopic volume, without any dose deposit in front or behind the target volume. Our infrared laser pulses produce high density avalanches of low energy electrons via laser filamentation, a phenomenon that results in a spatial energy density and temporal dose rate that both exceed by orders of magnitude any values previously reported even for the most intense clinical radiotherapy systems. Moreover, we show that (i) the type of final damage and its mechanisms in aqueous media, at the molecular and biomolecular level, is comparable to that of conventional ionizing radiation, and (ii) at the tumor tissue level in an animal cancer model, the laser irradiation method shows clear therapeutic benefits.

Spatiotemporal radiotherapy planning using a global optimization approach

NASA Astrophysics Data System (ADS)

Adibi, Ali; Salari, Ehsan

2018-02-01

This paper aims at quantifying the extent of potential therapeutic gain, measured using biologically effective dose (BED), that can be achieved by altering the radiation dose distribution over treatment sessions in fractionated radiotherapy. To that end, a spatiotemporally integrated planning approach is developed, where the spatial and temporal dose modulations are optimized simultaneously. The concept of equivalent uniform BED (EUBED) is used to quantify and compare the clinical quality of spatiotemporally heterogeneous dose distributions in target and critical structures. This gives rise to a large-scale non-convex treatment-plan optimization problem, which is solved using global optimization techniques. The proposed spatiotemporal planning approach is tested on two stylized cancer cases resembling two different tumor sites and sensitivity analysis is performed for radio-biological and EUBED parameters. Numerical results validate that spatiotemporal plans are capable of delivering a larger BED to the target volume without increasing the BED in critical structures compared to conventional time-invariant plans. In particular, this additional gain is attributed to the irradiation of different regions of the target volume at different treatment sessions. Additionally, the trade-off between the potential therapeutic gain and the number of distinct dose distributions is quantified, which suggests a diminishing marginal gain as the number of dose distributions increases.

Modeling and Validation of Performance Limitations for the Optimal Design of Interferometric and Intensity-Modulated Fiber Optic Displacement Sensors

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

Moro, Erik A.

Optical fiber sensors offer advantages over traditional electromechanical sensors, making them particularly well-suited for certain measurement applications. Generally speaking, optical fiber sensors respond to a desired measurand through modulation of an optical signal's intensity, phase, or wavelength. Practically, non-contacting fiber optic displacement sensors are limited to intensity-modulated and interferometric (or phase-modulated) methodologies. Intensity-modulated fiber optic displacement sensors relate target displacement to a power measurement. The simplest intensity-modulated sensor architectures are not robust to environmental and hardware fluctuations, since such variability may cause changes in the measured power level that falsely indicate target displacement. Differential intensity-modulated sensors have been implemented, offeringmore » robustness to such intensity fluctuations, and the speed of these sensors is limited only by the combined speed of the photodetection hardware and the data acquisition system (kHz-MHz). The primary disadvantages of intensity-modulated sensing are the relatively low accuracy (?m-mm for low-power sensors) and the lack of robustness, which consequently must be designed, often with great difficulty, into the sensor's architecture. White light interferometric displacement sensors, on the other hand, offer increased accuracy and robustness. Unlike their monochromatic-interferometer counterparts, white light interferometric sensors offer absolute, unambiguous displacement measurements over large displacement ranges (cm for low-power, 5 mW, sources), necessitating no initial calibration, and requiring no environmental or feedback control. The primary disadvantage of white light interferometric displacement sensors is that their utility in dynamic testing scenarios is limited, both by hardware bandwidth and by their inherent high-sensitivity to Doppler-effects. The decision of whether to use either an intensity-modulated interferometric sensor depends on an appropriate performance function (e.g., desired displacement range, accuracy, robustness, etc.). In this dissertation, the performance limitations of a bundled differential intensity-modulated displacement sensor are analyzed, where the bundling configuration has been designed to optimize performance. The performance limitations of a white light Fabry-Perot displacement sensor are also analyzed. Both these sensors are non-contacting, but they have access to different regions of the performance-space. Further, both these sensors have different degrees of sensitivity to experimental uncertainty. Made in conjunction with careful analysis, the decision of which sensor to deploy need not be an uninformed one.« less

Dosimetric advantages of generalised equivalent uniform dose-based optimisation on dose–volume objectives in intensity-modulated radiotherapy planning for bilateral breast cancer

PubMed Central

Lee, T-F; Ting, H-M; Chao, P-J; Wang, H-Y; Shieh, C-S; Horng, M-F; Wu, J-M; Yeh, S-A; Cho, M-Y; Huang, E-Y; Huang, Y-J; Chen, H-C; Fang, F-M

2012-01-01

Objective We compared and evaluated the differences between two models for treating bilateral breast cancer (BBC): (i) dose–volume-based intensity-modulated radiation treatment (DV plan), and (ii) dose–volume-based intensity-modulated radiotherapy with generalised equivalent uniform dose-based optimisation (DV-gEUD plan). Methods The quality and performance of the DV plan and DV-gEUD plan using the Pinnacle3® system (Philips, Fitchburg, WI) were evaluated and compared in 10 patients with stage T2–T4 BBC. The plans were delivered on a Varian 21EX linear accelerator (Varian Medical Systems, Milpitas, CA) equipped with a Millennium 120 leaf multileaf collimator (Varian Medical Systems). The parameters analysed included the conformity index, homogeneity index, tumour control probability of the planning target volume (PTV), the volumes V20 Gy and V30 Gy of the organs at risk (OAR, including the heart and lungs), mean dose and the normal tissue complication probability. Results Both plans met the requirements for the coverage of PTV with similar conformity and homogeneity indices. However, the DV-gEUD plan had the advantage of dose sparing for OAR: the mean doses of the heart and lungs, lung V20 Gy, and heart V30 Gy in the DV-gEUD plan were lower than those in the DV plan (p<0.05). Conclusions A better result can be obtained by starting with a DV-generated plan and then improving it by adding gEUD-based improvements to reduce the number of iterations and to improve the optimum dose distribution. Advances to knowledge The DV-gEUD plan provided superior dosimetric results for treating BBC in terms of PTV coverage and OAR sparing than the DV plan, without sacrificing the homogeneity of dose distribution in the PTV. PMID:23091290

Investigating multi-objective fluence and beam orientation IMRT optimization

NASA Astrophysics Data System (ADS)

Potrebko, Peter S.; Fiege, Jason; Biagioli, Matthew; Poleszczuk, Jan

2017-07-01

Radiation Oncology treatment planning requires compromises to be made between clinical objectives that are invariably in conflict. It would be beneficial to have a ‘bird’s-eye-view’ perspective of the full spectrum of treatment plans that represent the possible trade-offs between delivering the intended dose to the planning target volume (PTV) while optimally sparing the organs-at-risk (OARs). In this work, the authors demonstrate Pareto-aware radiotherapy evolutionary treatment optimization (PARETO), a multi-objective tool featuring such bird’s-eye-view functionality, which optimizes fluence patterns and beam angles for intensity-modulated radiation therapy (IMRT) treatment planning. The problem of IMRT treatment plan optimization is managed as a combined monolithic problem, where all beam fluence and angle parameters are treated equally during the optimization. To achieve this, PARETO is built around a powerful multi-objective evolutionary algorithm, called Ferret, which simultaneously optimizes multiple fitness functions that encode the attributes of the desired dose distribution for the PTV and OARs. The graphical interfaces within PARETO provide useful information such as: the convergence behavior during optimization, trade-off plots between the competing objectives, and a graphical representation of the optimal solution database allowing for the rapid exploration of treatment plan quality through the evaluation of dose-volume histograms and isodose distributions. PARETO was evaluated for two relatively complex clinical cases, a paranasal sinus and a pancreas case. The end result of each PARETO run was a database of optimal (non-dominated) treatment plans that demonstrated trade-offs between the OAR and PTV fitness functions, which were all equally good in the Pareto-optimal sense (where no one objective can be improved without worsening at least one other). Ferret was able to produce high quality solutions even though a large number of parameters, such as beam fluence and beam angles, were included in the optimization.

Stochastic optimization of intensity modulated radiotherapy to account for uncertainties in patient sensitivity

NASA Astrophysics Data System (ADS)

Kåver, Gereon; Lind, Bengt K.; Löf, Johan; Liander, Anders; Brahme, Anders

1999-12-01

The aim of the present work is to better account for the known uncertainties in radiobiological response parameters when optimizing radiation therapy. The radiation sensitivity of a specific patient is usually unknown beyond the expectation value and possibly the standard deviation that may be derived from studies on groups of patients. Instead of trying to find the treatment with the highest possible probability of a desirable outcome for a patient of average sensitivity, it is more desirable to maximize the expectation value of the probability for the desirable outcome over the possible range of variation of the radiation sensitivity of the patient. Such a stochastic optimization will also have to consider the distribution function of the radiation sensitivity and the larger steepness of the response for the individual patient. The results of stochastic optimization are also compared with simpler methods such as using biological response `margins' to account for the range of sensitivity variation. By using stochastic optimization, the absolute gain will typically be of the order of a few per cent and the relative improvement compared with non-stochastic optimization is generally less than about 10 per cent. The extent of this gain varies with the level of interpatient variability as well as with the difficulty and complexity of the case studied. Although the dose changes are rather small (<5 Gy) there is a strong desire to make treatment plans more robust, and tolerant of the likely range of variation of the radiation sensitivity of each individual patient. When more accurate predictive assays of the radiation sensitivity for each patient become available, the need to consider the range of variations can be reduced considerably.

Analytical modeling and feasibility study of a multi-GPU cloud-based server (MGCS) framework for non-voxel-based dose calculations.

PubMed

Neylon, J; Min, Y; Kupelian, P; Low, D A; Santhanam, A

2017-04-01

In this paper, a multi-GPU cloud-based server (MGCS) framework is presented for dose calculations, exploring the feasibility of remote computing power for parallelization and acceleration of computationally and time intensive radiotherapy tasks in moving toward online adaptive therapies. An analytical model was developed to estimate theoretical MGCS performance acceleration and intelligently determine workload distribution. Numerical studies were performed with a computing setup of 14 GPUs distributed over 4 servers interconnected by a 1 Gigabits per second (Gbps) network. Inter-process communication methods were optimized to facilitate resource distribution and minimize data transfers over the server interconnect. The analytically predicted computation time predicted matched experimentally observations within 1-5 %. MGCS performance approached a theoretical limit of acceleration proportional to the number of GPUs utilized when computational tasks far outweighed memory operations. The MGCS implementation reproduced ground-truth dose computations with negligible differences, by distributing the work among several processes and implemented optimization strategies. The results showed that a cloud-based computation engine was a feasible solution for enabling clinics to make use of fast dose calculations for advanced treatment planning and adaptive radiotherapy. The cloud-based system was able to exceed the performance of a local machine even for optimized calculations, and provided significant acceleration for computationally intensive tasks. Such a framework can provide access to advanced technology and computational methods to many clinics, providing an avenue for standardization across institutions without the requirements of purchasing, maintaining, and continually updating hardware.

Treatment of left sided breast cancer for a patient with funnel chest: Volumetric-modulated arc therapy vs. 3D-CRT and intensity-modulated radiotherapy

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

Haertl, Petra M., E-mail: petra.haertl@klinik.uni-regensburg.de; Pohl, Fabian; Weidner, Karin

2013-04-01

This case study presents a rare case of left-sided breast cancer in a patient with funnel chest, which is a technical challenge for radiation therapy planning. To identify the best treatment technique for this case, 3 techniques were compared: conventional tangential fields (3D conformal radiotherapy [3D-CRT]), intensity-modulated radiotherapy (IMRT), and volumetric-modulated arc therapy (VMAT). The plans were created for a SynergyS® (Elekta, Ltd, Crawley, UK) linear accelerator with a BeamModulator™ head and 6-MV photons. The planning system was Oncentra Masterplan® v3.3 SP1 (Nucletron BV, Veenendal, Netherlands). Calculations were performed with collapsed cone algorithm. Dose prescription was 50.4 Gy to themore » average of the planning target volume (PTV). PTV coverage and homogeneity was comparable for all techniques. VMAT allowed reducing dose to the ipsilateral organs at risk (OAR) and the contralateral breast compared with IMRT and 3D-CRT: The volume of the left lung receiving 20 Gy was 19.3% for VMAT, 26.1% for IMRT, and 32.4% for 3D-CRT. In the heart, a D{sub 15%} of 9.7 Gy could be achieved with VMAT compared with 14 Gy for IMRT and 46 Gy for 3D-CRT. In the contralateral breast, D{sub 15%} was 6.4 Gy for VMAT, 8.8 Gy for IMRT, and 10.2 Gy for 3D-CRT. In the contralateral lung, however, the lowest dose was achieved with 3D-CRT with D{sub 10%} of 1.7 Gy for 3D-CRT, and 6.7 Gy for both IMRT and VMAT. The lowest number of monitor units (MU) per 1.8-Gy fraction was required by 3D-CRT (192 MU) followed by VMAT (518 MU) and IMRT (727 MU). Treatment time was similar for 3D-CRT (3 min) and VMAT (4 min) but substantially increased for IMRT (13 min). VMAT is considered the best treatment option for the presented case of a patient with funnel chest. It allows reducing dose in most OAR without compromising target coverage, keeping delivery time well below 5 minutes.« less

Intensity-modulated radiotherapy improves lymph node coverage and dose to critical structures compared with three-dimensional conformal radiation therapy in clinically localized prostate cancer

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

Wang-Chesebro, Alice; Xia Ping; Coleman, Joy

2006-11-01

Purpose: The aim of this study was to quantify gains in lymph node coverage and critical structure dose reduction for whole-pelvis (WP) and extended-field (EF) radiotherapy in prostate cancer using intensity-modulated radiotherapy (IMRT) compared with three-dimensional conformal radiotherapy (3DCRT) for the first treatment phase of 45 Gy in the concurrent treatment of lymph nodes and prostate. Methods and Materials: From January to August 2005, 35 patients with localized prostate cancer were treated with pelvic IMRT; 7 had nodes defined up to L5-S1 (Group 1), and 28 had nodes defined above L5-S1 (Group 2). Each patient had 2 plans retrospectively generated:more » 1 WP 3DCRT plan using bony landmarks, and 1 EF 3DCRT plan to cover the vascular defined volumes. Dose-volume histograms for the lymph nodes, rectum, bladder, small bowel, and penile bulb were compared by group. Results: For Group 1, WP 3DCRT missed 25% of pelvic nodes with the prescribed dose 45 Gy and missed 18% with the 95% prescribed dose 42.75 Gy, whereas WP IMRT achieved V{sub 45Gy} = 98% and V{sub 42.75Gy} = 100%. Compared with WP 3DCRT, IMRT reduced bladder V{sub 45Gy} by 78%, rectum V{sub 45Gy} by 48%, and small bowel V{sub 45Gy} by 232 cm{sup 3}. EF 3DCRT achieved 95% coverage of nodes for all patients at high cost to critical structures. For Group 2, IMRT decreased bladder V{sub 45Gy} by 90%, rectum V{sub 45Gy} by 54% and small bowel V{sub 45Gy} by 455 cm{sup 3} compared with EF 3DCRT. Conclusion: In this study WP 3DCRT missed a significant percentage of pelvic nodes. Although EF 3DCRT achieved 95% pelvic nodal coverage, it increased critical structure doses. IMRT improved pelvic nodal coverage while decreasing dose to bladder, rectum, small bowel, and penile bulb. For patients with extended node involvement, IMRT especially decreases small bowel dose.« less

Comparison of survival rates between 3D conformal radiotherapy and intensity-modulated radiotherapy in patients with stage III non-small cell lung cancer.

PubMed

Kong, Moonkyoo; Hong, Seong Eon

2016-01-01

Randomized trials showing a clear survival benefit of intensity-modulated radiotherapy (IMRT) over 3-dimensional conformal radiotherapy (3D-CRT) in the treatment of lung cancer are lacking. This study compared the survival rates of patients with stage III non-small cell lung cancer who were treated with either 3D-CRT or IMRT and analyzed the prognostic factors for survival. From January 2008 to July 2015, 19 patients were treated with IMRT and 30 were treated with 3D-CRT in our institution. The choice between 3D-CRT and IMRT was determined by the physician based on tumor extent and general condition of the patients. The primary endpoint of this study was overall survival. The secondary endpoints were loco-regional recurrence-free survival, distant metastasis-free survival, and the incidence of radiation-induced lung and esophageal toxicities. The 1- and 2-year overall survival rates were 94.7% and 77.1% in the IMRT group and 76.7% and 52.5% in the 3D-CRT group, respectively. The overall survival rates of the IMRT group were higher than those of the 3D-CRT group; however, these differences were not statistically significant ( P =0.072). Gross tumor volume was significantly associated with the overall survival rate. The 1- and 2-year loco-regional recurrence-free survival rates were 63.2% and 51% in the IMRT group and 67.5% and 48.1% in the 3D-CRT group ( P =0.897), respectively. The 1- and 2-year distant metastasis-free survival rates were 78.9% and 68.4% in the IMRT group and 62.6% and 40.9% in the 3D-CRT group ( P =0.120), respectively. Chemotherapy and treatment interruption were significantly associated with distant metastasis-free survival. IMRT showed comparable or better overall survival compared with 3D-CRT in patients with stage III non-small cell lung cancer. To confirm the results of this study, further randomized prospective trials comparing IMRT with 3D-CRT are warranted.

Propensity Score-based Comparison of Long-term Outcomes With 3-Dimensional Conformal Radiotherapy vs Intensity-Modulated Radiotherapy for Esophageal Cancer

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

Lin, Steven H., E-mail: SHLin@mdanderson.org; Wang Lu; Myles, Bevan

2012-12-01

Purpose: Although 3-dimensional conformal radiotherapy (3D-CRT) is the worldwide standard for the treatment of esophageal cancer, intensity modulated radiotherapy (IMRT) improves dose conformality and reduces the radiation exposure to normal tissues. We hypothesized that the dosimetric advantages of IMRT should translate to substantive benefits in clinical outcomes compared with 3D-CRT. Methods and Materials: An analysis was performed of 676 nonrandomized patients (3D-CRT, n=413; IMRT, n=263) with stage Ib-IVa (American Joint Committee on Cancer 2002) esophageal cancers treated with chemoradiotherapy at a single institution from 1998-2008. An inverse probability of treatment weighting and inclusion of propensity score (treatment probability) as amore » covariate were used to compare overall survival time, interval to local failure, and interval to distant metastasis, while accounting for the effects of other clinically relevant covariates. The propensity scores were estimated using logistic regression analysis. Results: A fitted multivariate inverse probability weighted-adjusted Cox model showed that the overall survival time was significantly associated with several well-known prognostic factors, along with the treatment modality (IMRT vs 3D-CRT, hazard ratio 0.72, P<.001). Compared with IMRT, 3D-CRT patients had a significantly greater risk of dying (72.6% vs 52.9%, inverse probability of treatment weighting, log-rank test, P<.0001) and of locoregional recurrence (P=.0038). No difference was seen in cancer-specific mortality (Gray's test, P=.86) or distant metastasis (P=.99) between the 2 groups. An increased cumulative incidence of cardiac death was seen in the 3D-CRT group (P=.049), but most deaths were undocumented (5-year estimate, 11.7% in 3D-CRT vs 5.4% in IMRT group, Gray's test, P=.0029). Conclusions: Overall survival, locoregional control, and noncancer-related death were significantly better after IMRT than after 3D-CRT. Although these results need confirmation, IMRT should be considered for the treatment of esophageal cancer.« less

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

PubMed Central

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

2012-01-01

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

A feasibility study: Selection of a personalized radiotherapy fractionation schedule using spatiotemporal optimization

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

Kim, Minsun, E-mail: mk688@uw.edu; Stewart, Robert D.; Phillips, Mark H.

2015-11-15

Purpose: To investigate the impact of using spatiotemporal optimization, i.e., intensity-modulated spatial optimization followed by fractionation schedule optimization, to select the patient-specific fractionation schedule that maximizes the tumor biologically equivalent dose (BED) under dose constraints for multiple organs-at-risk (OARs). Methods: Spatiotemporal optimization was applied to a variety of lung tumors in a phantom geometry using a range of tumor sizes and locations. The optimal fractionation schedule for a patient using the linear-quadratic cell survival model depends on the tumor and OAR sensitivity to fraction size (α/β), the effective tumor doubling time (T{sub d}), and the size and location of tumormore » target relative to one or more OARs (dose distribution). The authors used a spatiotemporal optimization method to identify the optimal number of fractions N that maximizes the 3D tumor BED distribution for 16 lung phantom cases. The selection of the optimal fractionation schedule used equivalent (30-fraction) OAR constraints for the heart (D{sub mean} ≤ 45 Gy), lungs (D{sub mean} ≤ 20 Gy), cord (D{sub max} ≤ 45 Gy), esophagus (D{sub max} ≤ 63 Gy), and unspecified tissues (D{sub 05} ≤ 60 Gy). To assess plan quality, the authors compared the minimum, mean, maximum, and D{sub 95} of tumor BED, as well as the equivalent uniform dose (EUD) for optimized plans to conventional intensity-modulated radiation therapy plans prescribing 60 Gy in 30 fractions. A sensitivity analysis was performed to assess the effects of T{sub d} (3–100 days), tumor lag-time (T{sub k} = 0–10 days), and the size of tumors on optimal fractionation schedule. Results: Using an α/β ratio of 10 Gy, the average values of tumor max, min, mean BED, and D{sub 95} were up to 19%, 21%, 20%, and 19% larger than those from conventional prescription, depending on T{sub d} and T{sub k} used. Tumor EUD was up to 17% larger than the conventional prescription. For fast proliferating tumors with T{sub d} less than 10 days, there was no significant increase in tumor BED but the treatment course could be shortened without a loss in tumor BED. The improvement in the tumor mean BED was more pronounced with smaller tumors (p-value = 0.08). Conclusions: Spatiotemporal optimization of patient plans has the potential to significantly improve local tumor control (larger BED/EUD) of patients with a favorable geometry, such as smaller tumors with larger distances between the tumor target and nearby OAR. In patients with a less favorable geometry and for fast growing tumors, plans optimized using spatiotemporal optimization and conventional (spatial-only) optimization are equivalent (negligible differences in tumor BED/EUD). However, spatiotemporal optimization yields shorter treatment courses than conventional spatial-only optimization. Personalized, spatiotemporal optimization of treatment schedules can increase patient convenience and help with the efficient allocation of clinical resources. Spatiotemporal optimization can also help identify a subset of patients that might benefit from nonconventional (large dose per fraction) treatments that are ineligible for the current practice of stereotactic body radiation therapy.« less

Hippocampus-sparing radiotherapy using volumetric modulated arc therapy (VMAT) to the primary brain tumor: the result of dosimetric study and neurocognitive function assessment.

PubMed

Kim, Kyung Su; Wee, Chan Woo; Seok, Jin-Yong; Hong, Joo Wan; Chung, Jin-Beom; Eom, Keun-Yong; Kim, Jae-Sung; Kim, Chae-Yong; Park, Young Ho; Kim, Yu Jung; Kim, In Ah

2018-02-20

We hypothesized that hippocampal-sparing radiotherapy via volumetric modulated arc therapy (VMAT) could preserve the neurocognitive function (NCF) of patients with primary brain tumors treated with radiotherapy. We reviewed data from patients with primary brain tumors who underwent hippocampal-sparing brain radiotherapy via VMAT between February 2014 and December 2015. The optimization criteria for the contralateral hippocampus was a maximum dose (D max ) of less than 17 Gy. For NCF evaluations, the Seoul Verbal Learning Test for total recall, delayed recall, and recognition (SVLT-TR, DR, and Recognition) was performed at baseline and at seven months after radiotherapy. A total of 26 patients underwent NCF testing seven months after radiotherapy. Their median age was 49.5 years (range 26-77 years), and 14 (53.8%) had grade III/IV tumors. The median D max to the contralateral hippocampus was 16.4 Gy (range 3.5-63.4). The median mean dose to the contralateral hippocampus, expressed as equivalent to a 2-Gy dose (EQD 2/2 ), was 7.4 Gy 2 (0.7-13.1). The mean relative changes in SVLT-TR, SVLT-DR, and SVLT-Recognition at seven months compared to the baseline were - 7.7% (95% confidence interval [CI], - 19.6% to 4.2%), - 9.2% (95% CI, - 25.4% to 7.0%), and - 3.4% (- 12.7% to 5.8%), respectively. Two patients (7.7%) showed deteriorated NCF in the SVLT-TR and SVLT-DR, and three (11.5%) in the SVLT-Recognition. The mean dose of the left hippocampus and bilateral hippocampi were significantly higher in patients showing deterioration of the SVLT-TR and SVLT-Recognition than in those without deterioration. The contralateral hippocampus could be effectively spared in patients with primary brain tumor via VMAT to preserve the verbal memory function. Further investigation is needed to identify those patients who will most benefit from hippocampal-sparing radiotherapy of the primary brain tumor.

Incorporating uncertainty and motion in Intensity Modulated Radiation Therapy treatment planning

NASA Astrophysics Data System (ADS)

Martin, Benjamin Charles

In radiation therapy, one seeks to destroy a tumor while minimizing the damage to surrounding healthy tissue. Intensity Modulated Radiation Therapy (IMRT) uses overlapping beams of x-rays that add up to a high dose within the target and a lower dose in the surrounding healthy tissue. IMRT relies on optimization techniques to create high quality treatments. Unfortunately, the possible conformality is limited by the need to ensure coverage even if there is organ movement or deformation. Currently, margins are added around the tumor to ensure coverage based on an assumed motion range. This approach does not ensure high quality treatments. In the standard IMRT optimization problem, an objective function measures the deviation of the dose from the clinical goals. The optimization then finds the beamlet intensities that minimize the objective function. When modeling uncertainty, the dose delivered from a given set of beamlet intensities is a random variable. Thus the objective function is also a random variable. In our stochastic formulation we minimize the expected value of this objective function. We developed a problem formulation that is both flexible and fast enough for use on real clinical cases. While working on accelerating the stochastic optimization, we developed a technique of voxel sampling. Voxel sampling is a randomized algorithms approach to a steepest descent problem based on estimating the gradient by only calculating the dose to a fraction of the voxels within the patient. When combined with an automatic sampling rate adaptation technique, voxel sampling produced an order of magnitude speed up in IMRT optimization. We also develop extensions of our results to Intensity Modulated Proton Therapy (IMPT). Due to the physics of proton beams the stochastic formulation yields visibly different and better plans than normal optimization. The results of our research have been incorporated into a software package OPT4D, which is an IMRT and IMPT optimization tool that we developed.

MCTP system model based on linear programming optimization of apertures obtained from sequencing patient image data maps.

PubMed

Ureba, A; Salguero, F J; Barbeiro, A R; Jimenez-Ortega, E; Baeza, J A; Miras, H; Linares, R; Perucha, M; Leal, A

2014-08-01

The authors present a hybrid direct multileaf collimator (MLC) aperture optimization model exclusively based on sequencing of patient imaging data to be implemented on a Monte Carlo treatment planning system (MC-TPS) to allow the explicit radiation transport simulation of advanced radiotherapy treatments with optimal results in efficient times for clinical practice. The planning system (called CARMEN) is a full MC-TPS, controlled through aMATLAB interface, which is based on the sequencing of a novel map, called "biophysical" map, which is generated from enhanced image data of patients to achieve a set of segments actually deliverable. In order to reduce the required computation time, the conventional fluence map has been replaced by the biophysical map which is sequenced to provide direct apertures that will later be weighted by means of an optimization algorithm based on linear programming. A ray-casting algorithm throughout the patient CT assembles information about the found structures, the mass thickness crossed, as well as PET values. Data are recorded to generate a biophysical map for each gantry angle. These maps are the input files for a home-made sequencer developed to take into account the interactions of photons and electrons with the MLC. For each linac (Axesse of Elekta and Primus of Siemens) and energy beam studied (6, 9, 12, 15 MeV and 6 MV), phase space files were simulated with the EGSnrc/BEAMnrc code. The dose calculation in patient was carried out with the BEAMDOSE code. This code is a modified version of EGSnrc/DOSXYZnrc able to calculate the beamlet dose in order to combine them with different weights during the optimization process. Three complex radiotherapy treatments were selected to check the reliability of CARMEN in situations where the MC calculation can offer an added value: A head-and-neck case (Case I) with three targets delineated on PET/CT images and a demanding dose-escalation; a partial breast irradiation case (Case II) solved with photon and electron modulated beams (IMRT + MERT); and a prostatic bed case (Case III) with a pronounced concave-shaped PTV by using volumetric modulated arc therapy. In the three cases, the required target prescription doses and constraints on organs at risk were fulfilled in a short enough time to allow routine clinical implementation. The quality assurance protocol followed to check CARMEN system showed a high agreement with the experimental measurements. A Monte Carlo treatment planning model exclusively based on maps performed from patient imaging data has been presented. The sequencing of these maps allows obtaining deliverable apertures which are weighted for modulation under a linear programming formulation. The model is able to solve complex radiotherapy treatments with high accuracy in an efficient computation time.

A Double-Blind Placebo-Controlled Randomized Clinical Trial With Magnesium Oxide to Reduce Intrafraction Prostate Motion for Prostate Cancer Radiotherapy

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

Lips, Irene M., E-mail: i.m.lips@umcutrecht.nl; Gils, Carla H. van; Kotte, Alexis N.T.J.

2012-06-01

Purpose: To investigate whether magnesium oxide during external-beam radiotherapy for prostate cancer reduces intrafraction prostate motion in a double-blind, placebo-controlled randomized trial. Methods and Materials: At the Department of Radiotherapy, prostate cancer patients scheduled for intensity-modulated radiotherapy (77 Gy in 35 fractions) using fiducial marker-based position verification were randomly assigned to receive magnesium oxide (500 mg twice a day) or placebo during radiotherapy. The primary outcome was the proportion of patients with clinically relevant intrafraction prostate motion, defined as the proportion of patients who demonstrated in {>=}50% of the fractions an intrafraction motion outside a range of 2 mm. Secondarymore » outcome measures included quality of life and acute toxicity. Results: In total, 46 patients per treatment arm were enrolled. The primary endpoint did not show a statistically significant difference between the treatment arms with a percentage of patients with clinically relevant intrafraction motion of 83% in the magnesium oxide arm as compared with 80% in the placebo arm (p = 1.00). Concerning the secondary endpoints, exploratory analyses demonstrated a trend towards worsened quality of life and slightly more toxicity in the magnesium oxide arm than in the placebo arm; however, these differences were not statistically significant. Conclusions: Magnesium oxide is not effective in reducing the intrafraction prostate motion during external-beam radiotherapy, and therefore there is no indication to use it in clinical practice for this purpose.« less

Design of Hybrid Silicon and Lithium Niobate Active Region for Electro-optical Modulation

DTIC Science & Technology

2017-03-01

bandwidth our group has proposed a Mach-Zehnder traveling -wave type modulator with optimized cross section dimensions using a similar material stack as...increases the electric field intensity available to the Pockel’s effect. At the same time , the induced metal loss increases as the electrodes become...Gopalakrishnan et al., “Performance and modeling of broadband LiNbO3 traveling wave optical intensity modulators,” J. Light. Technol., vol. 12, no. 10, pp

From technological advances to biological understanding: The main steps toward high-precision RT in breast cancer.

PubMed

Leonardi, Maria Cristina; Ricotti, Rosalinda; Dicuonzo, Samantha; Cattani, Federica; Morra, Anna; Dell'Acqua, Veronica; Orecchia, Roberto; Jereczek-Fossa, Barbara Alicja

2016-10-01

Radiotherapy improves local control in breast cancer (BC) patients which increases overall survival in the long term. Improvements in treatment planning and delivery and a greater understanding of BC behaviour have laid the groundwork for high-precision radiotherapy, which is bound to further improve the therapeutic index. Precise identification of target volumes, better coverage and dose homogeneity have had a positive impact on toxicity and local control. The conformity of treatment dose due to three-dimensional radiotherapy and new techniques such as intensity modulated radiotherapy makes it possible to spare surrounding normal tissue. The widespread use of dose-volume constraints and histograms have increased awareness of toxicity. Real time image guidance has improved geometric precision and accuracy, together with the implementation of quality assurance programs. Advances in the precision of radiotherapy is also based on the choice of the appropriate fractionation and approach. Adaptive radiotherapy is not only a technical concept, but is also a biological concept based on the knowledge that different types of BC have distinctive patterns of locoregional spread. A greater understanding of cancer biology helps in choosing the treatment best suited to a particular situation. Biomarkers predictive of response play a crucial role. The combination of radiotherapy with molecular targeted therapies may enhance radiosensitivity, thus increasing the cytotoxic effects and improving treatment response. The appropriateness of an alternative fractionation, partial breast irradiation, dose escalating/de-escalating approaches, the extent of nodal irradiation have been examined for all the BC subtypes. The broadened concept of adaptive radiotherapy is vital to high-precision treatments. Copyright © 2016 Elsevier Ltd. All rights reserved.

SU-C-17A-01: MRI-Based Radiotherapy Treatment Planning In Pelvis

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

Hsu, S; Cao, Y; Jolly, S

2014-06-15

Purpose: To support radiotherapy dose calculation, synthetic CT (MRCT) image volumes need to represent the electron density of tissues with sufficient accuracy. This study compares CT and MRCT for pelvic radiotherapy. Methods: CT and multi-contrast MRI acquired using T1- based Dixon, T2 TSE, and PETRA sequences were acquired on an IRBapproved protocol patient. A previously published method was used to create a MRCT image volume by applying fuzzy classification on T1- weighted and calculated water image volumes (air and fluid voxels were excluded using thresholds applied to PETRA and T2-weighted images). The correlation of pelvic bone intensity between CT andmore » MRCT was investigated. Two treatment plans, based on CT and MRCT, were performed to mimic treatment for: (a) pelvic bone metastasis with a 16MV parallel beam arrangement, and (b) gynecological cancer with 6MV volumetric modulated arc therapy (VMAT) using two full arcs. The CT-calculated fluence maps were used to recalculate doses using the MRCT-derived density grid. The dose-volume histograms and dose distributions were compared. Results: Bone intensities in the MRCT volume correlated linearly with CT intensities up to 800 HU (containing 96% of the bone volume), and then decreased with CT intensity increase (4% volume). There was no significant difference in dose distributions between CT- and MRCTbased plans, except for the rectum and bladder, for which the V45 differed by 15% and 9%, respectively. These differences may be attributed to normal and visualized organ movement and volume variations between CT and MR scans. Conclusion: While MRCT had lower bone intensity in highly-dense bone, this did not cause significant dose deviations from CT due to its small percentage of volume. These results indicate that treatment planning using MRCT could generate comparable dose distributions to that using CT, and further demonstrate the feasibility of using MRI-alone to support Radiation Oncology workflow. NIH R01EB016079.« less

Dose–volume-related dysphagia after constrictor muscles definition in head and neck cancer intensity-modulated radiation treatment

PubMed Central

Mazzola, R; Ricchetti, F; Fiorentino, A; Fersino, S; Giaj Levra, N; Naccarato, S; Sicignano, G; Albanese, S; Di Paola, G; Alterio, D; Ruggieri, R

2014-01-01

Objective: Dysphagia remains a side effect influencing the quality of life of patients with head and neck cancer (HNC) after radiotherapy. We evaluated the relationship between planned dose involvement and acute and late dysphagia in patients with HNC treated with intensity-modulated radiation therapy (IMRT), after a recontouring of constrictor muscles (PCs) and the cricopharyngeal muscle (CM). Methods: Between December 2011 and December 2013, 56 patients with histologically proven HNC were treated with IMRT or volumetric-modulated arc therapy. The PCs and CM were recontoured. Correlations between acute and late toxicity and dosimetric parameters were evaluated. End points were analysed using univariate logistic regression. Results: An increasing risk to develop acute dysphagia was observed when constraints to the middle PCs were not respected [mean dose (Dmean) ≥50 Gy, maximum dose (Dmax) >60 Gy, V50 >70% with a p = 0.05]. The superior PC was not correlated with acute toxicity but only with late dysphagia. The inferior PC was not correlated with dysphagia; for the CM only, Dmax >60 Gy was correlated with acute dysphagia ≥ grade 2. Conclusion: According to our analysis, the superior PC has a major role, being correlated with dysphagia at 3 and 6 months after treatments; the middle PC maintains this correlation only at 3 months from the beginning of radiotherapy, but it does not have influence on late dysphagia. The inferior PC and CM have a minimum impact on swallowing symptoms. Advances in knowledge: We used recent guidelines to define dose constraints of the PCs and CM. Two results emerge in the present analysis: the superior PC influences late dysphagia, while the middle PC influences acute dysphagia. PMID:25348370

Combination of intensity-based image registration with 3D simulation in radiation therapy.

PubMed

Li, Pan; Malsch, Urban; Bendl, Rolf

2008-09-07

Modern techniques of radiotherapy like intensity modulated radiation therapy (IMRT) make it possible to deliver high dose to tumors of different irregular shapes at the same time sparing surrounding healthy tissue. However, internal tumor motion makes precise calculation of the delivered dose distribution challenging. This makes analysis of tumor motion necessary. One way to describe target motion is using image registration. Many registration methods have already been developed previously. However, most of them belong either to geometric approaches or to intensity approaches. Methods which take account of anatomical information and results of intensity matching can greatly improve the results of image registration. Based on this idea, a combined method of image registration followed by 3D modeling and simulation was introduced in this project. Experiments were carried out for five patients 4DCT lung datasets. In the 3D simulation, models obtained from images of end-exhalation were deformed to the state of end-inhalation. Diaphragm motions were around -25 mm in the cranial-caudal (CC) direction. To verify the quality of our new method, displacements of landmarks were calculated and compared with measurements in the CT images. Improvement of accuracy after simulations has been shown compared to the results obtained only by intensity-based image registration. The average improvement was 0.97 mm. The average Euclidean error of the combined method was around 3.77 mm. Unrealistic motions such as curl-shaped deformations in the results of image registration were corrected. The combined method required less than 30 min. Our method provides information about the deformation of the target volume, which we need for dose optimization and target definition in our planning system.

Evidence-based optimal number of radiotherapy fractions for cancer: A useful tool to estimate radiotherapy demand.

PubMed

Wong, Karen; Delaney, Geoff P; Barton, Michael B

2016-04-01

The recently updated optimal radiotherapy utilisation model estimated that 48.3% of all cancer patients should receive external beam radiotherapy at least once during their disease course. Adapting this model, we constructed an evidence-based model to estimate the optimal number of fractions for notifiable cancers in Australia to determine equipment and workload implications. The optimal number of fractions was calculated based on the frequency of specific clinical conditions where radiotherapy is indicated and the evidence-based recommended number of fractions for each condition. Sensitivity analysis was performed to assess the impact of variables on the model. Of the 27 cancer sites, the optimal number of fractions for the first course of radiotherapy ranged from 0 to 23.3 per cancer patient, and 1.5 to 29.1 per treatment course. Brain, prostate and head and neck cancers had the highest average number of fractions per course. Overall, the optimal number of fractions was 9.4 per cancer patient (range 8.7-10.0) and 19.4 per course (range 18.0-20.7). These results provide valuable data for radiotherapy services planning and comparison with actual practice. The model can be easily adapted by inserting population-specific epidemiological data thus making it applicable to other jurisdictions. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

[Brachytherapy for head and neck cancers].

PubMed

Peiffert, D; Coche-Dequéant, B; Lapeyre, M; Renard, S

2018-05-29

The main indications of the brachytherapy of head and neck cancers are the limited tumours of the lip, the nose, the oral cavity and the oropharynx. Nasopharynx tumours are nowadays treated by intensity-modulated radiotherapy. This technique can be exclusive, associated with external radiotherapy or postoperative. It can also be a salvage treatment for the second primaries in previously irradiated areas. If the low dose rate brachytherapy rules remain the reference, the pulse dose rate technique allows the prescription of the dose rate and the optimisation of the dose distribution. Results of high dose rate brachytherapy are now published. This paper reports the recommendations of the Gec-ESTRO, published in 2017, and takes into account the data of the historical low dose rate series, and is upgraded with the pulsed-dose rate and high dose rate series. Copyright © 2018. Published by Elsevier SAS.

Intensity-modulated proton therapy further reduces normal tissue exposure during definitive therapy for locally advanced distal esophageal tumors: a dosimetric study.

PubMed

Welsh, James; Gomez, Daniel; Palmer, Matthew B; Riley, Beverly A; Mayankkumar, Amin V; Komaki, Ritsuko; Dong, Lei; Zhu, X Ronald; Likhacheva, Anna; Liao, Zhongxing; Hofstetter, Wayne L; Ajani, Jaffer A; Cox, James D

2011-12-01

We have previously found that ≤ 75% of treatment failures after chemoradiotherapy for unresectable esophageal cancer appear within the gross tumor volume and that intensity-modulated (photon) radiotherapy (IMRT) might allow dose escalation to the tumor without increasing normal tissue toxicity. Proton therapy might allow additional dose escalation, with even lower normal tissue toxicity. In the present study, we compared the dosimetric parameters for photon IMRT with that for intensity-modulated proton therapy (IMPT) for unresectable, locally advanced, distal esophageal cancer. Four plans were created for each of 10 patients. IMPT was delivered using anteroposterior (AP)/posteroanterior beams, left posterior oblique/right posterior oblique (LPO/RPO) beams, or AP/LPO/RPO beams. IMRT was delivered with a concomitant boost to the gross tumor volume. The dose was 65.8 Gy to the gross tumor volume and 50.4 Gy to the planning target volume in 28 fractions. Relative to IMRT, the IMPT (AP/posteroanterior) plan led to considerable reductions in the mean lung dose (3.18 vs. 8.27 Gy, p<.0001) and the percentage of lung volume receiving 5, 10, and 20 Gy (p≤.0006) but did not reduce the cardiac dose. The IMPT LPO/RPO plan also reduced the mean lung dose (4.9 Gy vs. 8.2 Gy, p<.001), the heart dose (mean cardiac dose and percentage of the cardiac volume receiving 10, 20, and 30 Gy, p≤.02), and the liver dose (mean hepatic dose 5 Gy vs. 14.9 Gy, p<.0001). The IMPT AP/LPO/RPO plan led to considerable reductions in the dose to the lung (p≤.005), heart (p≤.003), and liver (p≤.04). Compared with IMRT, IMPT for distal esophageal cancer lowered the dose to the heart, lung, and liver. The AP/LPO/RPO beam arrangement was optimal for sparing all three organs. The dosimetric benefits of protons will need to be tailored to each patient according to their specific cardiac and pulmonary risks. IMPT for esophageal cancer will soon be investigated further in a prospective trial at our institution. Copyright © 2011 Elsevier Inc. All rights reserved.

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

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

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

2015-04-01

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

Feasibility of Adaptive MR-guided Stereotactic Body Radiotherapy (SBRT) of Lung Tumors

PubMed Central

Simpson, Garrett N; Llorente, Ricardo; Samuels, Michael A; Dogan, Nesrin

2018-01-01

Online adaptive radiotherapy (ART) with frequent imaging has the potential to improve dosimetric accuracy by accounting for anatomical and functional changes during the course of radiotherapy. Presented are three interesting cases that provide an assessment of online adaptive magnetic resonance-guided radiotherapy (MRgRT) for lung stereotactic body radiotherapy (SBRT). The study includes three lung SBRT cases, treated on an MRgRT system where MR images were acquired for planning and prior to each treatment fraction. Prescription dose ranged from 48 to 50 Gy in four to five fractions, normalized to where 95% of the planning target volume (PTV) was covered by 100% of the prescription dose. The process begins with the gross tumor volume (GTV), PTV, spinal cord, lungs, heart, and esophagus being delineated on the planning MRI. The treatment plan was then generated using a step-and-shoot intensity modulated radiotherapy (IMRT) technique, which utilized a Monte Carlo dose calculation. Next, the target and organs at risk (OAR) contours from the planning MRI were deformably propagated to the daily setup MRIs. These deformed contours were reviewed and modified by the physician. To determine the efficacy of ART, two different strategies were explored: 1) Calculating the plan created for the planning MR on each fraction setup MR dataset (Non-Adapt) and 2) creating a new optimized IMRT plan on the fraction setup MR dataset (FxAdapt). The treatment plans from both strategies were compared using the clinical dose-volume constraints. PTV coverage constraints were not met for 33% Non-Adapt fractions; all FxAdapt fractions met this constraint. Eighty-eight percent of all OAR constraints studied were better on FxAdapt plans, while 12% of OAR constraints were superior on Non-Adapt fractions. The OAR that garnered the largest benefit would be the uninvolved lung, with superior sparing in 92% of the FxAdapt studied. Similar, but less pronounced, benefits from adaptive planning were experienced for the spinal cord, chest wall, and esophagus. Online adaptive MR-guided lung SBRT can provide better target conformality and homogeneity and OAR sparing compared with non-adaptive SBRT in selected cases. Conversely, if the PTV isn’t adjacent to multiple OARs, then the benefit from ART may be limited. Further studies, which incorporate a larger cohort of patients with uniform prescriptions, are needed to thoroughly evaluate the benefits of daily online ART during MRgRT. PMID:29872603

Effect of MLC leaf position, collimator rotation angle, and gantry rotation angle errors on intensity-modulated radiotherapy plans for nasopharyngeal carcinoma

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

Bai, Sen; Li, Guangjun; Wang, Maojie

The purpose of this study was to investigate the effect of multileaf collimator (MLC) leaf position, collimator rotation angle, and accelerator gantry rotation angle errors on intensity-modulated radiotherapy plans for nasopharyngeal carcinoma. To compare dosimetric differences between the simulating plans and the clinical plans with evaluation parameters, 6 patients with nasopharyngeal carcinoma were selected for simulation of systematic and random MLC leaf position errors, collimator rotation angle errors, and accelerator gantry rotation angle errors. There was a high sensitivity to dose distribution for systematic MLC leaf position errors in response to field size. When the systematic MLC position errors weremore » 0.5, 1, and 2 mm, respectively, the maximum values of the mean dose deviation, observed in parotid glands, were 4.63%, 8.69%, and 18.32%, respectively. The dosimetric effect was comparatively small for systematic MLC shift errors. For random MLC errors up to 2 mm and collimator and gantry rotation angle errors up to 0.5°, the dosimetric effect was negligible. We suggest that quality control be regularly conducted for MLC leaves, so as to ensure that systematic MLC leaf position errors are within 0.5 mm. Because the dosimetric effect of 0.5° collimator and gantry rotation angle errors is negligible, it can be concluded that setting a proper threshold for allowed errors of collimator and gantry rotation angle may increase treatment efficacy and reduce treatment time.« less

On Voxel based Iso-Tumor Control Probabilty and Iso-Complication Maps for Selective Boosting and Selective Avoidance Intensity Modulated Radiotherapy

PubMed Central

Kim, Yusung; Tomé, Wolfgang A.

2010-01-01

Summary Voxel based iso-Tumor Control Probability (TCP) maps and iso-Complication maps are proposed as a plan-review tool especially for functional image-guided intensity-modulated radiotherapy (IMRT) strategies such as selective boosting (dose painting) and conformal avoidance IMRT. The maps employ voxel-based phenomenological biological dose-response models for target volumes and normal organs. Two IMRT strategies for prostate cancer, namely conventional uniform IMRT delivering an EUD = 84 Gy (equivalent uniform dose) to the entire PTV and selective boosting delivering an EUD = 82 Gy to the entire PTV, are investigated, to illustrate the advantages of this approach over iso-dose maps. Conventional uniform IMRT did yield a more uniform isodose map to the entire PTV while selective boosting did result in a nonuniform isodose map. However, when employing voxel based iso-TCP maps selective boosting exhibited a more uniform tumor control probability map compared to what could be achieved using conventional uniform IMRT, which showed TCP cold spots in high-risk tumor subvolumes despite delivering a higher EUD to the entire PTV. Voxel based iso-Complication maps are presented for rectum and bladder, and their utilization for selective avoidance IMRT strategies are discussed. We believe as the need for functional image guided treatment planning grows, voxel based iso-TCP and iso-Complication maps will become an important tool to assess the integrity of such treatment plans. PMID:21151734

Local control after intensity-modulated radiotherapy for head-and-neck rhabdomyosarcoma.

PubMed

Curtis, Amarinthia E; Okcu, M Fatih; Chintagumpala, Murali; Teh, Bin S; Paulino, Arnold C

2009-01-01

To examine the patterns of failure in patients treated with intensity-modulated radiotherapy (IMRT) for head-and-neck rhabdomyosarcoma (RMS). Between 1998 and 2005, 19 patients with a diagnosis of head-and-neck RMS received IMRT at The Methodist Hospital. There were 11 male and 8 female patients, with a median age of 6 years at time of irradiation. Tumor location was parameningeal in 7, orbital in 6, and other head-and-neck RMS in 6. Chemotherapy was given to all patients, with vincristine, actinomycin D, and cyclophosphamide being the most common regimen (n = 18). The median prescribed dose was 5040 cGy. The clinical target volume included the gross tumor volume with a 1.5-cm margin. The median duration of follow-up for surviving patients was 56 months. The 4-year overall survival and local control rates were 76% and 92.9%, respectively. One patient developed a local failure in the high-dose region of the radiation field; there were no marginal failures. Distant metastasis was seen in 4 patients. Overall survival was 42.9% for parameningeal sites and 100% for other sites (p < 0.01). Late toxicities were seen in 7 patients. Two secondary malignancies occurred in 1 child with embryonal RMS of the face and a p53 mutation. Local control was excellent in patients receiving IMRT for head-and-neck RMS. Patterns of local failure reveal no marginal failures in this group of patients.

Evaluation of the Dosimetric Feasibility of Hippocampal Sparing Intensity-Modulated Radiotherapy in Patients with Locally Advanced Nasopharyngeal Carcinoma

PubMed Central

Gan, Hua; Denniston, Kyle A.; Li, Sicong; Tan, Wenyong; Wang, Zhaohua

2014-01-01

Purpose The objective of this study was to evaluate the dosimetric feasibility of using hippocampus (HPC) sparing intensity-modulated radiotherapy (IMRT) in patients with locally advanced nasopharyngeal carcinoma (NPC). Materials/Methods Eight cases of either T3 or T4 NPC were selected for this study. Standard IMRT treatment plans were constructed using the volume and dose constraints for the targets and organs at risk (OAR) per Radiation Therapy Oncology Group (RTOG) 0615 protocol. Experimental plans were constructed using the same criteria, with the addition of the HPC as an OAR. The two dose-volume histograms for each case were compared for the targets and OARs. Results All plans achieved the protocol dose criteria. The homogeneity index, conformity index, and coverage index for the planning target volumes (PTVs) were not significantly compromised by the avoidance of the HPC. The doses to all OARs, excluding the HPC, were similar. Both the dose (Dmax, D2%, D40%, Dmean, Dmedian, D98% and Dmin) and volume (V5, V10, V15, V20, V30, V40 and V50) parameters for the HPC were significantly lower in the HPC sparing plans (p<0.05), except for Dmin (P = 0.06) and V5 (P = 0.12). Conclusions IMRT for patients with locally advanced NPC exposes the HPC to a significant radiation dose. HPC sparing IMRT planning significantly decreases this dose, with minimal impact on the therapeutic targets and other OARs. PMID:24587184

The Evolution of and Risk Factors for Neck Muscle Atrophy and Weakness in Nasopharyngeal Carcinoma Treated With Intensity-Modulated Radiotherapy

PubMed Central

Zhang, Lu-Lu; Mao, Yan-Ping; Zhou, Guan-Qun; Tang, Ling-Long; Qi, Zhen-Yu; Lin, Li; Yao, Ji-Jin; Ma, Jun; Lin, Ai-Hua; Sun, Ying

2015-01-01

Abstract The aim of this study was to investigate the evolution of sternocleidomastoid muscle (SCM) atrophy in nasopharyngeal carcinoma (NPC) patients following intensity-modulated radiotherapy (IMRT), and the relationship between SCM atrophy and neck weakness. Data were retrospectively analyzed from 223 biopsy-proven NPC patients with no distant metastasis who underwent IMRT with or without chemotherapy. The volume of SCM was measured on pretreatment magnetic resonance imaging (MRI), and MRIs were conducted 1, 2, and 3 years after the completion of IMRT. Change in SCM volume was calculated and classified using the late effects of normal tissues–subjective, objective, management, and analytic system. The grade of neck muscle weakness, classified by the Common Terminology Criteria for Adverse Events V 3.0, was measured 3 years after the completion of IMRT. The average SCM atrophy ratio was −10.97%, −18.65%, and −22.25% at 1, 2, and 3 years postirradiation, respectively. Multivariate analysis indicated N stage and the length of time after IMRT were independent prognostic variables. There were significant associations between the degree of SCM atrophy and neck weakness. Radical IMRT can cause significant SCM atrophy in NPC patients. A more advanced N stage was associated with more severe SCM atrophy, but no difference was observed between N2 and N3. SCM atrophy progresses over time during the 3 years following IMRT. Grade of SCM atrophy is significantly associated with neck weakness. PMID:26252307

The Evolution of and Risk Factors for Neck Muscle Atrophy and Weakness in Nasopharyngeal Carcinoma Treated With Intensity-Modulated Radiotherapy: A Retrospective Study in an Endemic Area.

PubMed

Zhang, Lu-Lu; Mao, Yan-Ping; Zhou, Guan-Qun; Tang, Ling-Long; Qi, Zhen-Yu; Lin, Li; Yao, Ji-Jin; Ma, Jun; Lin, Ai-Hua; Sun, Ying

2015-08-01

The aim of this study was to investigate the evolution of sternocleidomastoid muscle (SCM) atrophy in nasopharyngeal carcinoma (NPC) patients following intensity-modulated radiotherapy (IMRT), and the relationship between SCM atrophy and neck weakness.Data were retrospectively analyzed from 223 biopsy-proven NPC patients with no distant metastasis who underwent IMRT with or without chemotherapy. The volume of SCM was measured on pretreatment magnetic resonance imaging (MRI), and MRIs were conducted 1, 2, and 3 years after the completion of IMRT. Change in SCM volume was calculated and classified using the late effects of normal tissues-subjective, objective, management, and analytic system. The grade of neck muscle weakness, classified by the Common Terminology Criteria for Adverse Events V 3.0, was measured 3 years after the completion of IMRT.The average SCM atrophy ratio was -10.97%, -18.65%, and -22.25% at 1, 2, and 3 years postirradiation, respectively. Multivariate analysis indicated N stage and the length of time after IMRT were independent prognostic variables. There were significant associations between the degree of SCM atrophy and neck weakness.Radical IMRT can cause significant SCM atrophy in NPC patients. A more advanced N stage was associated with more severe SCM atrophy, but no difference was observed between N2 and N3. SCM atrophy progresses over time during the 3 years following IMRT. Grade of SCM atrophy is significantly associated with neck weakness.

Improving target coverage and organ-at-risk sparing in intensity-modulated radiotherapy for cervical oesophageal cancer using a simple optimisation method.

PubMed

Lu, Jia-Yang; Cheung, Michael Lok-Man; Huang, Bao-Tian; Wu, Li-Li; Xie, Wen-Jia; Chen, Zhi-Jian; Li, De-Rui; Xie, Liang-Xi

2015-01-01

To assess the performance of a simple optimisation method for improving target coverage and organ-at-risk (OAR) sparing in intensity-modulated radiotherapy (IMRT) for cervical oesophageal cancer. For 20 selected patients, clinically acceptable original IMRT plans (Original plans) were created, and two optimisation methods were adopted to improve the plans: 1) a base dose function (BDF)-based method, in which the treatment plans were re-optimised based on the original plans, and 2) a dose-controlling structure (DCS)-based method, in which the original plans were re-optimised by assigning additional constraints for hot and cold spots. The Original, BDF-based and DCS-based plans were compared with regard to target dose homogeneity, conformity, OAR sparing, planning time and monitor units (MUs). Dosimetric verifications were performed and delivery times were recorded for the BDF-based and DCS-based plans. The BDF-based plans provided significantly superior dose homogeneity and conformity compared with both the DCS-based and Original plans. The BDF-based method further reduced the doses delivered to the OARs by approximately 1-3%. The re-optimisation time was reduced by approximately 28%, but the MUs and delivery time were slightly increased. All verification tests were passed and no significant differences were found. The BDF-based method for the optimisation of IMRT for cervical oesophageal cancer can achieve significantly better dose distributions with better planning efficiency at the expense of slightly more MUs.

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

PubMed

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

2011-01-13

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

Investigation of the feasibility of elective irradiation to neck level Ib using intensity-modulated radiotherapy for patients with nasopharyngeal carcinoma: a retrospective analysis.

PubMed

Zhang, Fan; Cheng, Yi-Kan; Li, Wen-Fei; Guo, Rui; Chen, Lei; Sun, Ying; Mao, Yan-Ping; Zhou, Guan-Qun; Liu, Xu; Liu, Li-Zhi; Lin, Ai-Hua; Tang, Ling-Long; Ma, Jun

2015-10-15

To assess the feasibility of elective neck irradiation to level Ib in nasopharyngeal carcinoma (NPC) using intensity-modulated radiation therapy (IMRT). We retrospectively analyzed 1438 patients with newly-diagnosed, non-metastatic and biopsy-proven NPC treated with IMRT. Greatest dimension of level IIa LNs (DLN-IIa) ≥ 20 mm and/or level IIa LNs with extracapsular spread (ES), oropharynx involvement and positive bilateral cervical lymph nodes (CLNs) were independently significantly associated with metastasis to level Ib LN at diagnosis. No recurrence at level Ib was observed in the 904 patients without these characteristics (median follow-up, 38.7 months; range, 1.3-57.8 months), these patients were classified as low risk. Level Ib irradiation was not an independent risk factor for locoregional failure-free survival, distant failure-free survival, failure-free survival or overall survival in low risk patients. The frequency of grade ≥ 2 subjective xerostomia at 12 months after radiotherapy was not significantly different between low risk patients who received level Ib-sparing, unilateral level Ib-covering or bilateral level Ib-covering IMRT. Level Ib-sparing IMRT should be safe and feasible for patients without a DLN-IIa ≥ 20 mm and/or level IIa LNs with ES, positive bilateral CLNs or oropharynx involvement at diagnosis. Further investigations based on specific criteria for dose constraints for the submandibular glands are warranted to confirm the benefit of elective level Ib irradiation.

Mueller-Stokes characterization and optimization of a liquid crystal on silicon display showing depolarization.

PubMed

Márquez, A; Moreno, I; Iemmi, C; Lizana, A; Campos, J; Yzuel, M J

2008-02-04

In this paper we characterize the polarimetric properties of a liquid crystal on silicon display (LCoS), including depolarization and diattenuation which are usually not considered when applying the LCoS in diffractive or adaptive optics. On one hand, we have found that the LCoS generates a certain degree (that can be larger than a 10%) of depolarized light, which depends on the addressed gray level and on the incident state of polarization (SOP), and can not be ignored in the above mentioned applications. The main origin of the depolarized light is related with temporal fluctuations of the SOP of the light reflected by the LCoS. The Mueller matrix of the LCoS is measured as a function of the gray level, which enables for a numerical optimization of the intensity modulation configurations. In particular we look for maximum intensity contrast modulation or for constant intensity modulation. By means of a heuristic approach we show that, using elliptically polarized light, amplitude-mostly or phase-mostly modulation can be obtained at a wavelength of 633 nm.

Proton therapy to the subdiaphragmatic region in the management of patients with Hodgkin lymphoma.

PubMed

Sachsman, Suzanne; Hoppe, Bradford S; Mendenhall, Nancy P; Holtzman, Adam; Li, Zuofeng; Slayton, William; Joyce, Mike; Sandler, Eric; Flampouri, Stella

2015-07-01

Twelve consecutive patients with classical Hodgkin lymphoma (HL) involving diaphragmatic or subdiaphragmatic regions were treated on an institutional review board-approved outcomes tracking protocol. All patients underwent treatment with proton therapy following chemotherapy and had comparative three-dimensional conformal photon radiotherapy (3DCRT) and intensity-modulated radiotherapy (IMRT) plans to evaluate differences in dose to organs at risk (OARs). Among the cohort, stomach doses with 3DCRT, IMRT and proton therapy were 21 Gy (median), 14 Gy and 6 Gy, respectively. Median dose reductions with proton therapy compared with 3DCRT and IMRT were 13 Gy (p = 0.0022) and 8 Gy (p = 0.0022) for the stomach. Additionally, there was significant dose reduction using proton therapy for the liver, pancreas, bowel, left kidney and right kidney. Proton therapy reduces the dose to the stomach, liver, pancreas, small bowel and kidneys compared with 3DCRT or IMRT in patients with HL requiring abdominal radiotherapy. These dose reductions are expected to translate into lower risks of secondary cancers and other late toxicities in survivors of HL.

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

NASA Astrophysics Data System (ADS)

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

2016-03-01

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

Olminska and colleagues' study, "Conversion of the helical tomotherapy plans to the step-and-shoot IMRT plans for patients with hip prosthesis during radiotherapy for prostate cancer" was interesting to read.

PubMed

Cihan, Yasemin Benderli

2016-11-01

Olmińska and colleagues' study, Olmińska et al. (2016) was interesting to read [1]. While prasining the authors for their great work, I want to emphasize e few points. In the recent years, with the development of new device technology, Intensity Modulated Radiotherapy (IMRT) and complex treatment modalities such as stereotactic radiosurgery and helical tomotherapy were started to be implemented. Thus, due to increased local control of tumor growth and reduction of dose received by surrounding critical organs, serious complications were avoided. In this new treatment modality, while calculating appropriate dose, all the parameters such as patient anatomy and characteristics of radiation should be taken into account. Besides, during conformal radiotherapy, if hip prosthesis is located around or in the clinical target volume (CTV), type, thickness and density of biomaterial should be considered to avoid dose differences. Copyright © 2016 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

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

Boehling, Nicholas S.; Grosshans, David R., E-mail: dgrossha@mdanderson.org; Bluett, Jaques B.

Purpose: Cranial irradiation in pediatric patients is associated with serious long-term adverse effects. We sought to determine whether both three-dimensional conformal proton radiotherapy (3D-PRT) and intensity-modulated proton therapy (IMPT) compared with intensity-modulated radiotherapy (IMRT) decrease integral dose to brain areas known to harbor neuronal stem cells, major blood vessels, and other normal brain structures for pediatric patients with craniopharyngiomas. Methods and Materials: IMRT, forward planned, passive scattering proton, and IMPT plans were generated and optimized for 10 pediatric patients. The dose was 50.4 Gy (or cobalt Gy equivalent) delivered in 28 fractions with the requirement for planning target volume (PTV)more » coverage of 95% or better. Integral dose data were calculated from differential dose-volume histograms. Results: The PTV target coverage was adequate for all modalities. IMRT and IMPT yielded the most conformal plans in comparison to 3D-PRT. Compared with IMRT, 3D-PRT and IMPT plans had a relative reduction of integral dose to the hippocampus (3D-PRT, 20.4; IMPT, 51.3%{sup Asterisk-Operator }), dentate gyrus (27.3, 75.0%{sup Asterisk-Operator }), and subventricular zone (4.5, 57.8%{sup Asterisk-Operator }). Vascular organs at risk also had reduced integral dose with the use of proton therapy (anterior cerebral arteries, 33.3{sup Asterisk-Operator }, 100.0%{sup Asterisk-Operator }; middle cerebral arteries, 25.9%{sup Asterisk-Operator }, 100%{sup Asterisk-Operator }; anterior communicating arteries, 30.8{sup Asterisk-Operator }, 41.7%{sup Asterisk-Operator }; and carotid arteries, 51.5{sup Asterisk-Operator }, 77.6{sup Asterisk-Operator }). Relative reduction of integral dose to the infratentorial brain (190.7{sup Asterisk-Operator }, 109.7%{sup Asterisk-Operator }), supratentorial brain without PTV (9.6, 26.8%{sup Asterisk-Operator }), brainstem (45.6, 22.4%{sup Asterisk-Operator }), and whole brain without PTV (19.4{sup Asterisk-Operator }, 34.4%{sup Asterisk-Operator }) were recorded with the use of proton therapy. ({sup Asterisk-Operator }Differences were significant based on Friedman's test with Bonferroni-Dunn correction, {alpha} = 0.05) Conclusions: The current study found that proton therapy was able to avoid excess integral radiation dose to a variety of normal structures at all dose levels while maintaining equal target coverage. Future studies will examine the clinical benefits of these dosimetric advantages.« less

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

Krayenbuehl, Jerome Dipl.Phys. E.T.H.; Oertel, Susanne; Davis, J. Bernard

Purpose: The optimal technique for postoperative radiotherapy (RT) after extrapleural pleuropneumonectomy (EPP) of malignant pleural mesothelioma (MPM) remains debated. Methods and Materials: The data from 8 right-sided and 9 left-sided consecutive cases of MPM treated with RT after radical EPP were reviewed. Of the 17 patients, 8 had been treated with three-dimensional (3D) conformal RT (3D-CRT) and 9 with intensity-modulated RT (IMRT) with 6-MV photons. The clinical outcome and adverse events were assessed. For comparative planning, each case was replanned with 3D-CRT using photons and electrons or with IMRT. Homogeneity, doses to the organs at risk, and target volume coveragemore » were analyzed. Results: Both techniques yielded acceptable plans. The dose coverage and homogeneity of IMRT increased by 7.7% for the first planning target volume and 9.7% for the second planning target volume, ensuring {>=}95% of the prescribed dose compared with 3D-CRT (p < 0.01). Compared with 3D-CRT, IMRT increased the dose to the contralateral lung, with an increase in the mean lung dose of 7.8 Gy and an increase in the volume receiving 13 Gy and 20 Gy by 20.5% and 7.2%, respectively (p < 0.01). A negligible dose increase to the contralateral kidney and liver was observed. No differences were seen for the spinal cord and ipsilateral kidney. Two adverse events of clinical relevant lung toxicity were observed with IMRT. Conclusion: Intensity-modulated RT and 3D-CRT are both suitable for adjuvant RT. IMRT improves the planning target volume coverage but delivered greater doses to the organs at risk. Rigid dose constraints for the lung should be respected.« less

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

PubMed

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

2012-08-01

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

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

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

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

2011-12-01

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

Time-driven activity-based cost comparison of prostate cancer brachytherapy and intensity-modulated radiation therapy.

PubMed

Dutta, Sunil W; Bauer-Nilsen, Kristine; Sanders, Jason C; Trifiletti, Daniel M; Libby, Bruce; Lash, Donna H; Lain, Melody; Christodoulou, Deborah; Hodge, Constance; Showalter, Timothy N

To evaluate the delivery cost of frequently used radiotherapy options offered to patients with intermediate- to high-risk prostate cancer using time-driven activity-based costing and compare the results with Medicare reimbursement and relative value units (RVUs). Process maps were created to represent each step of prostate radiotherapy treatment at our institution. Salary data, equipment purchase costs, and consumable costs were factored into the cost analysis. The capacity cost rate was determined for each resource and calculated for each treatment option from initial consultation to its completion. Treatment options included low-dose-rate brachytherapy (LDR-BT), combined high-dose-rate brachytherapy single fraction boost with 25-fraction intensity-modulated radiotherapy (HDR-BT-IMRT), moderately hypofractionated 28-fraction IMRT, conventionally fractionated 39-fraction IMRT, and conventionally fractionated (2 Gy/fraction) 23-fraction pelvis irradiation with 16-fraction prostate boost. The total cost to deliver LDR-BT, HDR-BT-IMRT, moderately hypofractionated 28-fraction IMRT, conventionally fractionated 39-fraction IMRT, conventionally fractionated 39-fraction IMRT, and conventionally fractionated (2 Gy/fraction) 23-fraction pelvis irradiation with 16-fraction prostate boost was $2719, $6517, $4173, $5507, and $5663, respectively. Total reimbursement for each course was $3123, $10,156, $7862, $9725, and $10,377, respectively. Radiation oncology attending time was 1.5-2 times higher for treatment courses incorporating BT. Attending radiation oncologist's time consumed per RVU was higher with BT (4.83 and 2.56 minutes per RVU generated for LDR-BT and HDR-BT-IMRT, respectively) compared to without BT (1.41-1.62 minutes per RVU). Time-driven activity-based costing analysis identified higher delivery costs associated with prostate BT compared with IMRT alone. In light of recent guidelines promoting BT for intermediate- to high-risk disease, re-evaluation of payment policies is warranted to encourage BT delivery. Copyright © 2018 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.

Intensity-Modulated Radiotherapy Reduces Gastrointestinal Toxicity in Patients Treated With Androgen Deprivation Therapy for Prostate Cancer

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

Sharma, Navesh K.; Li Tianyu; Chen, David Y.

Purpose: Androgen deprivation therapy (AD) has been shown to increase late Grade 2 or greater rectal toxicity when used concurrently with three-dimensional conformal radiotherapy (3D-CRT). Intensity-modulated radiotherapy (IMRT) has the potential to reduce toxicity by limiting the radiation dose received by the bowel and bladder. The present study compared the genitourinary and gastrointestinal (GI) toxicity in men treated with 3D-CRT+AD vs. IMRT+AD. Methods and Materials: Between July 1992 and July 2004, 293 men underwent 3D-CRT (n = 170) or IMRT (n = 123) with concurrent AD (<6 months, n = 123; {>=}6 months, n = 170). The median radiation dosemore » was 76 Gy for 3D-CRT (International Commission on Radiation Units and Measurements) and 76 Gy for IMRT (95% to the planning target volume). Toxicity was assessed by a patient symptom questionnaire that was completed at each visit and recorded using a Fox Chase Modified Late Effects Normal Tissue Task radiation morbidity scale. Results: The mean follow-up was 86 months (standard deviation, 29.3) for the 3D-CRT group and 40 months (standard deviation, 9.7) for the IMRT group. Acute GI toxicity (odds ratio, 4; 95% confidence interval, 1.6-11.7; p = .005) was significantly greater with 3D-CRT than with IMRT and was independent of the AD duration (i.e., <6 vs. {>=}6 months). The interval to the development of late GI toxicity was significantly longer in the IMRT group. The 5-year Kaplan-Meier estimate for Grade 2 or greater GI toxicity was 20% for 3D-CRT and 8% for IMRT (p = .01). On multivariate analysis, Grade 2 or greater late GI toxicity (hazard ratio, 2.1; 95% confidence interval, 1.1-4.3; p = .04) was more prevalent in the 3D-CRT patients. Conclusion: Compared with 3D-CRT, IMRT significantly decreased the acute and late GI toxicity in patients treated with AD.« less

SU-E-T-608: Performance Comparison of Four Commercial Treatment Planning Systems Applied to Intensity-Modulated Radiotherapy

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

Cao, Y; Li, R; Chi, Z

Purpose: To compare the performances of four commercial treatment planning systems (TPS) used for the intensity-modulated radiotherapy (IMRT). Methods: Ten patients of nasopharyngeal (4 cases), esophageal (3 cases) and cervical (3 cases) cancer were randomly selected from a 3-month IMRT plan pool at one radiotherapy center. For each patient, four IMRT plans were newly generated by using four commercial TPS (Corvus, Monaco, Pinnacle and Xio), and then verified with Matrixx (two-dimensional array/IBA Company) on Varian23EX accelerator. A pass rate (PR) calculated from the Gamma index by OminiPro IMRT 1.5 software was evaluated at four plan verification standards (1%/1mm, 2%/2mm, 3%/3mm,more » 4%/4mm and 5%/5mm) for each treatment plan. Overall and multiple pairwise comparisons of PRs were statistically conducted by analysis of covariance (ANOVA) F and LSD tests among four TPSs. Results: Overall significant (p>0.05) differences of PRs were found among four TPSs with F test values of 3.8 (p=0.02), 21.1(>0.01), 14.0 (>0.01), 8.3(>0.01) at standards of 1%/1mm to 4%/4mm respectively, except at 5%/5mm standard with 2.6 (p=0.06). All means (standard deviation) of PRs at 3%/3mm of 94.3 ± 3.3 (Corvus), 98.8 ± 0.8 (Monaco), 97.5± 1.7 (Pinnacle), 98.4 ± 1.0 (Xio) were above 90% and met clinical requirement. Multiple pairwise comparisons had not demonstrated a consistent low or high pattern on either TPS. Conclusion: Matrixx dose verification results show that the validation pass rates of Monaco and Xio plans are relatively higher than those of the other two; Pinnacle plan shows slight higher pass rate than Corvus plan; lowest pass rate was achieved by the Corvus plan among these four kinds of TPS.« less

Dose-Dependent Pulmonary Toxicity After Postoperative Intensity-Modulated Radiotherapy for Malignant Pleural Mesothelioma

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

Rice, David C.; Smythe, W. Roy; Liao Zhongxing

Purpose: To determine the incidence of fatal pulmonary events after extrapleural pneumonectomy and hemithoracic intensity-modulated radiotherapy (IMRT) for malignant pleural mesothelioma. Methods and Materials: We retrospectively reviewed the records of 63 consecutive patients with malignant pleural mesothelioma who underwent extrapleural pneumonectomy and IMRT at University of Texas M. D. Anderson Cancer Center. The endpoints studied were pulmonary-related death (PRD) and non-cancer-related death within 6 months of IMRT. Results: Of the 63 patients, 23 (37%) had died within 6 months of IMRT (10 of recurrent cancer, 6 of pulmonary causes [pneumonia in 4 and pneumonitis in 2], and 7 of othermore » noncancer causes [pulmonary embolus in 2, sepsis after bronchopleural fistula in 1, and cause unknown but without pulmonary symptoms or recurrent disease in 4]). On univariate analysis, the factors that predicted for PRD were a lower preoperative ejection fraction (p = 0.021), absolute volume of lung spared at 10 Gy (p = 0.025), percentage of lung volume receiving {>=}20 Gy (V{sub 20}; p 0.002), and mean lung dose (p = 0.013). On multivariate analysis, only V{sub 20} was predictive of PRD (p = 0.017; odds ratio, 1.50; 95% confidence interval, 1.08-2.08) or non-cancer-related death (p = 0.033; odds ratio, 1.21; 95% confidence interval, 1.02-1.45). Conclusion: The results of our study have shown that fatal pulmonary toxicities were associated with radiation to the contralateral lung. V{sub 20} was the only independent determinant for risk of PRD or non-cancer-related death. The mean V{sub 20} of the non-PRD patients was considerably lower than that accepted during standard thoracic radiotherapy, implying that the V{sub 20} should be kept as low as possible after extrapleural pneumonectomy.« less

Intensity-modulated salvage radiotherapy with simultaneous integrated boost for local recurrence of prostate carcinoma: a pilot study on the place of PET-choline for guiding target volume delineation.

PubMed

Wahart, Aurélien; Guy, Jean-Baptiste; Vallard, Alexis; Geissler, Benjamin; Ben Mrad, Majed; Falk, Alexander T; Prevot, Nathalie; de Laroche, Guy; Rancoule, Chloé; Chargari, Cyrus; Magné, Nicolas

2016-01-01

The aim of this study was to report the first cases of salvage radiotherapy (RT) using the intensity-modulated radiotherapy (IMRT) with simultaneous integrated boost (SIB) targeted on choline positron emission tomography (PET) uptake in a local recurrent prostate cancer, after a radical prostatectomy. Four patients received salvage irradiation for biochemical relapse that occurred after the initial radical prostatectomy. The relapse occurred from 10 months to 6 years with PSA levels ranging from 2.35 to 4.86 ng ml(-1). For each patient, an (18)F-choline PET-CT showed a focal choline uptake in prostatic fossa, with standardized uptake value calculated on the basis of predicted lean body mass (SUL) max of 3.3-6.8. No involved lymph node or distant metastases were diagnosed. IMRT doses were of 62.7 Gy (1.9 Gy/fraction, 33 fractions), with a SIB of 69.3 Gy (2.1 Gy/fraction, 33 fractions) to a PET-guided target volume. Acute toxicities were limited. We observed no gastrointestinal toxicity ≥grade 2 and only one grade 2 genitourinary toxicity. At 1-month follow-up evaluation, no complication and a decrease in PSA level (6.8-43.8% of the pre-therapeutic level) were reported. After 4 months, a decrease in PSA level was obtained for all the patients, ranging from 30% to 70%. At a median follow-up of 15 months, PSA level was controlled for all the patients, but one of them experienced a distant lymph node recurrence. Salvage irradiation to the prostate bed with SIB guided by PET-CT is feasible, with biological efficacy and no major acute toxicity. IMRT with PET-oriented SIB for salvage treatment of prostate cancer is possible, without major acute toxicity.

A quantitative assessment of volumetric and anatomic changes of the parotid gland during intensity-modulated radiotherapy for head and neck cancer using serial computed tomography

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

Ajani, Abdallah A.; Qureshi, Muhammad M.; Kovalchuk, Nataliya

To evaluate the change in volume and movement of the parotid gland measured by serial contrast-enhanced computed tomography scans in patients with head and neck cancer treated with parotid-sparing intensity-modulated radiotherapy (IMRT). A prospective study was performed on 13 patients with head and neck cancer undergoing dose-painted IMRT to 69.96 Gy in 33 fractions. Serial computed tomography scans were performed at baseline, weeks 2, 4, and 6 of radiotherapy (RT), and at 6 weeks post-RT. The parotid volume was contoured at each scan, and the movement of the medial and lateral borders was measured. The patient's body weight was recordedmore » at each corresponding week during RT. Regression analyses were performed to ascertain the rate of change during treatment as a percent change per fraction in parotid volume and distance relative to baseline. The mean parotid volume decreased by 37.3% from baseline to week 6 of RT. The overall rate of change in parotid volume during RT was−1.30% per fraction (−1.67% and−0.91% per fraction in≥31 Gy and<31 Gy mean planned parotid dose groups, respectively, p = 0.0004). The movement of parotid borders was greater in the≥31 Gy mean parotid dose group compared with the<31 Gy group (0.22% per fraction and 0.14% per fraction for the lateral border and 0.19% per fraction and 0.06% per fraction for the medial border, respectively). The median change in body weight was−7.4% (range, 0.75% to−17.5%) during RT. A positive correlation was noted between change in body weight and parotid volume during the course of RT (Spearman correlation coefficient, r = 0.66, p<0.01). Head and neck IMRT results in a volume loss of the parotid gland, which is related to the planned parotid dose, and the patient's weight loss during RT.« less

Dosimetric and radiobiologic comparison of 3D conformal versus intensity modulated planning techniques for prostate bed radiotherapy.

PubMed

Koontz, Bridget F; Das, Shiva; Temple, Kathy; Bynum, Sigrun; Catalano, Suzanne; Koontz, Jason I; Montana, Gustavo S; Oleson, James R

2009-01-01

Adjuvant radiotherapy for locally advanced prostate cancer improves biochemical and clinical disease-free survival. While comparisons in intact prostate cancer show a benefit for intensity modulated radiation therapy (IMRT) over 3D conformal planning, this has not been studied for post-prostatectomy radiotherapy (RT). This study compares normal tissue and target dosimetry and radiobiological modeling of IMRT vs. 3D conformal planning in the postoperative setting. 3D conformal plans were designed for 15 patients who had been treated with IMRT planning for salvage post-prostatectomy RT. The same computed tomography (CT) and target/normal structure contours, as well as prescription dose, was used for both IMRT and 3D plans. Normal tissue complication probabilities (NTCPs) were calculated based on the dose given to the bladder and rectum by both plans. Dose-volume histogram and NTCP data were compared by paired t-test. Bladder and rectal sparing were improved with IMRT planning compared to 3D conformal planning. The volume of the bladder receiving at least 75% (V75) and 50% (V50) of the dose was significantly reduced by 28% and 17%, respectively (p = 0.002 and 0.037). Rectal dose was similarly reduced, V75 by 33% and V50 by 17% (p = 0.001 and 0.004). While there was no difference in the volume of rectum receiving at least 65 Gy (V65), IMRT planning significant reduced the volume receiving 40 Gy or more (V40, p = 0.009). Bladder V40 and V65 were not significantly different between planning modalities. Despite these dosimetric differences, there was no significant difference in the NTCP for either bladder or rectal injury. IMRT planning reduces the volume of bladder and rectum receiving high doses during post-prostatectomy RT. Because of relatively low doses given to the bladder and rectum, there was no statistically significant improvement in NTCP between the 3D conformal and IMRT plans.

Clinical Implications of the Tumor Volume Reduction Rate in Head-and-Neck Cancer During Definitive Intensity-Modulated Radiotherapy for Organ Preservation

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

Yang, Shih-Neng; Department of Biomedical Imaging and Radiological Science, China Medical University, Taichung, Taiwan; Liao, Chih-Ying

2011-03-15

Purpose: To investigate the prognostic value of the volume reduction rate (VRR) in patients with head-and-neck cancer treated with intensity-modulated radiotherapy (IMRT). Methods and Materials: Seventy-six patients with oropharyngeal cancer (OPC) and another 76 with hypopharyngeal cancer (HPC) were enrolled in volumetric analysis. All patients received allocated radiotherapy courses. Adaptive computed tomography was done 4 to 5 weeks after the start of IMRT. Primary tumor volume measurement was derived using separate images for the pretreatment gross tumor volume (pGTV) and the interval gross tumor volume. Results: In the OPC group, the pGTV ranged from 6.6 to 242.6 mL (mean, 49.9more » mL), whereas the value of the VRR ranged from 0.014 to 0.74 (mean, 0.43). In HPC patients, the pGTV ranged from 4.1 to 152.4 mL (mean, 35.6 mL), whereas the VRR ranged from -1.15 to 0.79 (mean, 0.33). Multivariate analysis of the primary tumor relapse-free survival for OPC revealed three prognostic factors: T4 tumor (p = 0.0001, hazard ratio 7.38), pGTV {>=}20 mL (p = 0.01, hazard ratio 10.61), and VRR <0.5 (p = 0.001, hazard ratio 6.49). Multivariate analysis of the primary tumor relapse-free survival for HPC showed two prognostic factors: pGTV {>=}30 mL (p = 0.001, hazard ratio 2.87) and VRR <0.5 (p = 0.03, hazard ratio 2.25). Conclusion: The VRR is an outcome predictor for local control in OPC and HPC patients treated with IMRT. Those with large tumor volumes or a VRR <0.5 should be considered for a salvage operation or a dose-escalation scheme.« less

Clinical applications of image guided-intensity modulated radiation therapy (IG-IMRT) for conformal avoidance of normal tissue

NASA Astrophysics Data System (ADS)

Gutierrez, Alonso Navar

2007-12-01

Recent improvements in imaging technology and radiation delivery have led to the development of advanced treatment techniques in radiotherapy which have opened the door for novel therapeutic approaches to improve the efficacy of radiation cancer treatments. Among these advances is image-guided, intensity modulated radiation therapy (IG-IMRT), in which imaging is incorporated to aid in inter-/intra-fractional target localization and to ensure accurate delivery of precise and highly conformal dose distributions. In principle, clinical implementation of IG-IMRT should improve normal tissue sparing and permit effective biological dose escalation thus widening the radiation therapeutic window and lead to increases in survival through improved local control of primary neoplastic diseases. Details of the development of three clinical applications made possible solely with IG-IMRT radiation delivery techniques are presented: (1) Laparoscopically implanted tissue expander radiotherapy (LITE-RT) has been developed to enhance conformal avoidance of normal tissue during the treatment of intra-abdominopelvic cancers. LITE-RT functions by geometrically displacing surrounding normal tissue and isolating the target volume through the interfractional inflation of a custom-shaped tissue expander throughout the course of treatment. (2) The unique delivery geometry of helical tomotherapy, a novel form of IG-IMRT, enables the delivery of composite treatment plan m which whole brain radiotherapy (WBRT) with hippocampal avoidance, hypothesized to reduce the risk of memory function decline and improve the patient's quality of life, and simultaneously integrated boost to multiple brain metastases to improve intracranial tumor control is achieved. (3) Escalation of biological dose to targets through integrated, selective subvolume boosts have been shown to efficiently increase tumor dose without significantly increasing normal tissue dose. Helical tomotherapy was used to investigate the feasibility of delivering a simultaneously integrated subvolume boost to canine nasal tumors and was found to dramatically increase estimated 1-year tumor control probability (TCP) without increasing the dose to the eyes, so as to preserve vision, and to the brain, so as to prevent neuropathy.

SU-E-T-275: Radiobiological Evaluation of Intensity Modulated Radiotherapy Treatment for Locally Advanced Head and Neck Squamous Cell Carcinomas

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

Rekha Reddy, B.; Ravikumar, M.; Tanvir Pasha, C.R

2014-06-01

Purpose: To evaluate the radiobiological outcome of Intensity Modulated Radiotherapy Treatment (IMRT) for locally advanced head and neck squamous cell carcinomas using HART (Histogram Analysis in Radiation Therapy; J Appl Clin Med Phys 11(1): 137–157, 2010) program and compare with the clinical outcomes. Methods: We have treated 20 patients of stage III and IV HNSCC Oropharynx and hypopharynx with accelerated IMRT technique and concurrent chemotherapy. Delineation of tumor and normal tissues were done using Danish Head and Neck Cancer Group (DAHANCA) contouring guidelines and radiotherapy was delivered to a dose of 70Gy in 35 fractions to the primary and involvedmore » lymph nodes, 63Gy to intermediate risk areas and 56 Gy to lower risk areas, Monday to Saturday, 6 Days/week using 6 MV Photons with an expected overall treatment time of 6 weeks. The TCP and NTCP's were calculated from the dose-volume histogram (DVH) statistics using the Poisson Statistics (PS) and JT Lyman models respectively and the Resultwas correlated with clinical outcomes of the patients with mean follow up of 24 months. Results: Using HART program, the TCP (0.89± 0.01) of primary tumor and the NTCP for parotids (0.20±0.12), spinal cord (0.05±0.01), esophagus (0.30±0.2), mandible (0.35±0.21), Oral cavity (0.37±0.18), Larynx (0.30±0.15) were estimated and correlated with clinical outcome of the patients. Conclusion: Accelerated IMRT with Chemotherapy is a clinical feasible option in the treatment of locally advanced HNSCC with encouraging initial tumour response and acceptable acute toxicities. The correlation between the clinical outcomes and radiobiological model estimated parameters using HART programs are found to be satisfactory.« less

Incidence and dosimetric parameters for brainstem necrosis following intensity modulated radiation therapy in nasopharyngeal carcinoma.

PubMed

Li, Yang-Chan; Chen, Fo-Ping; Zhou, Guan-Qun; Zhu, Jin-Han; Hu, Jiang; Kang, De-Hua; Wu, Chen-Fei; Lin, Li; Wang, Xiao-Ju; Ma, Jun; Sun, Ying

2017-10-01

To clarify the incidence of brainstem toxicity and perform a dose-volume analysis for the brainstem after long-term follow-up of a large cohort of nasopharyngeal carcinoma (NPC) patients who underwent intensity-modulated radiation therapy (IMRT). All patients with NPC treated with IMRT at Sun Yat-sen University Cancer Center between April 2009 and March 2012 were retrospectively reviewed. A total of 1544 patients with follow-up >12months and detailed treatment plan data were included. Radiotherapy was administered using the simultaneous integrated boost technique in 2.0-2.48Gy per fractions/28-33 fractions. Brainstem necrosis was defined as lesions with high signal intensity on T2-weighted images and low signal intensity on T1-weighted images, with or without enhancement after administration of contrast in follow-up MRI. After median follow-up of 79.7months (range, 12.2-85.6months), 2/1544 (0.13%) patients developed brainstem necrosis after intervals of 12.3 and 18.5months. Actuarial incidence of brainstem necrosis was 0.07%, 0.13%, 0.13% and 0.13% after 1, 2, 3 and 5years, respectively. Overall, 384 (24.9%), 153 (9.9%), 67 (4.3%), 39 (2.5%), 78 (5.1%), and 114 (7.4%) patients had excessive doses of D max ≥64Gy, D1cc>59Gy, D2cc>59Gy, aV50>5.9cc, aV55>2.7cc and aV60>0.9cc respectively, of whom only two developed brainstem necrosis. Brainstem necrosis is rare in NPC. The definitive criteria based on conventional radiotherapy cannot accurately predict the occurrence of brainstem necrosis after IMRT, thus more flexible definitive criteria with strict restrictions need to be defined. Copyright © 2017 Elsevier Ltd. All rights reserved.

SU-F-T-592: A Delivery QA-Free Approach for Adaptive Therapy of Prostate Cancer with Static Intensity Modulated Radiotherapy

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

Roth, T; Dooley, J; Zhu, T

2016-06-15

Purpose: Clinical implementations of adaptive radiotherapy (ART) are limited mainly by the requirement of delivery QA (DQA) prior to the treatment. Small segment size and small segment MU are two dominant factors causing failures of DQA. The aim of this project is to explore the feasibility of ART treatment without DQA by using a partial optimization approach. Methods: A retrospective simulation study was performed on two prostate cancer patients treated with SMLC-IMRT. The prescription was 180cGx25 fractions with daily CT-on-rail imaging for target alignment. For each patient, seven daily CTs were selected randomly across treatment course. The contours were deformablelymore » transferred from the simulation CT onto the daily CTs and modified appropriately. For each selected treatment, dose distributions from original beams were calculated on the daily treatment CTs (DCT plan). An ART plan was also created by optimizing the segmental MU only, while the segment shapes were preserved and the minimum MU constraint was respected. The overlaps, between PTV and the rectum, between PTV and the bladder, were normalized by the PTV volume. This ratio was used to characterize the difficulty of organs-at-risk (OAR) sparing. Results: Comparing to the original plan, PTV coverage was compromised significantly in DCT plans (82% ± 7%) while all ART plans preserved PTV coverage. ART plans showed similar OAR sparing as the original plan, such as V40Gy=11.2cc (ART) vs 11.4cc (original) for the rectum and D10cc=4580cGy vs 4605cGy for the bladder. The sparing of the rectum/bladder depends on overlap ratios. The sparing in ART was either similar or improved when overlap ratios in treatment CTs were smaller than those in original plan. Conclusion: A partial optimization method is developed that may make the real-time ART feasible on selected patients. Future research is warranted to quantify the applicability of the proposed method.« less

[Dosimetric comparing between protons beam and photons beam
for lung cancer radiotherapy: a meta-analysis].

PubMed

Tian, Guangwei; Li, Nan; Li, Guang

2013-05-01

The clinical evidences are not sufficient on the proton beam therapy of lung cancer for lacking of the RCTs on the comparing the proton with the photon beam in lung cancer radiotherapy. The aim of this study is to evaluate the dosimetry superiority of the proton beam and provide more valuable evidences to the clinical researches. Clinical trails of dosimetric comparing between protons beam and photons beam for lung cancer radiotherapy were obtained from the Cochrane library, Pubmed, EMbase, CBM, CNKI, VIP, and Wan Fang databases. The data included in the study were evaluated and analyzed using the Cochrane Collaboration's RevMan 5.2 software. Six trails were included. Compared to photon therapy (three-dimensional conformal photon radiotherapy, 3D-CRT), the proton therapy had a significantly lower total lung Dmean (MD=-4.15, 95%CI: -5.56--2.74, P<0.001) and V20, V10, V5 (MD=-10.92, 95%CI: -13.23--8.62, P<0.001); The V20, V10, V5 significantly decreased in proton therapy group. Compared to photon therapy (intensity-modulated photon radiotherapy, IMRT), V20, V10, V5 were also significantly lowered in proton therapy group (MD=-3.70, 95%CI: -5.31--2.10, P<0.001; MD=-8.86, 95%CI: -10.74--6.98, P<0.001; MD=-20.13, 95%CI: -27.11--13.14, P<0.001); The esophagus Dmean was not lowered, while the heart Dmean decreased in proton therapy group. Comparing to photon beam radiotherapy (3D-CRT and IMRT), proton beam therapy is advantageous in dosimetry of the lung cancer radiotherapy and recommended for clinical applying.

Dose specification for hippocampal sparing whole brain radiotherapy (HS WBRT): considerations from the UK HIPPO trial QA programme.

PubMed

Megias, Daniel; Phillips, Mark; Clifton-Hadley, Laura; Harron, Elizabeth; Eaton, David J; Sanghera, Paul; Whitfield, Gillian

2017-03-01

The HIPPO trial is a UK randomized Phase II trial of hippocampal sparing (HS) vs conventional whole-brain radiotherapy after surgical resection or radiosurgery in patients with favourable prognosis with 1-4 brain metastases. Each participating centre completed a planning benchmark case as part of the dedicated radiotherapy trials quality assurance programme (RTQA), promoting the safe and effective delivery of HS intensity-modulated radiotherapy (IMRT) in a multicentre trial setting. Submitted planning benchmark cases were reviewed using visualization for radiotherapy software (VODCA) evaluating plan quality and compliance in relation to the HIPPO radiotherapy planning and delivery guidelines. Comparison of the planning benchmark data highlighted a plan specified using dose to medium as an outlier by comparison with those specified using dose to water. Further evaluation identified that the reported plan statistics for dose to medium were lower as a result of the dose calculated at regions of PTV inclusive of bony cranium being lower relative to brain. Specification of dose to water or medium remains a source of potential ambiguity and it is essential that as part of a multicentre trial, consideration is given to reported differences, particularly in the presence of bone. Evaluation of planning benchmark data as part of an RTQA programme has highlighted an important feature of HS IMRT dosimetry dependent on dose being specified to water or medium, informing the development and undertaking of HS IMRT as part of the HIPPO trial. Advances in knowledge: The potential clinical impact of differences between dose to medium and dose to water are demonstrated for the first time, in the setting of HS whole-brain radiotherapy.

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

Sakanaka, Katsuyuki; Mizowaki, Takashi, E-mail: mizo@kuhp.kyoto-u.ac.jp; Hiraoka, Masahiro

Purpose: To investigate the dosimetric advantage of intensity-modulated radiotherapy (IMRT) for whole ventricles (WV) in patients with a localized intracranial germinoma receiving induction chemotherapy. Methods and Materials: Data from 12 consecutive patients with localized intracranial germinomas who received induction chemotherapy and radiotherapy were used. Four-field coplanar three-dimensional conformal radiotherapy (3D-CRT) and seven-field coplanar IMRT plans were created. In both plans, 24 Gy was prescribed in 12 fractions for the planning target volume (PTV) involving WV and tumor bed. In IMRT planning, optimization was conducted to reduce the doses to the organs at risk (OARs) as much as possible, keeping themore » minimum dose equivalent to that of 3D-CRT. The 3D-CRT and IMRT plans were compared in terms of the dose-volume statistics for target coverage and the OARs. Results: IMRT significantly increased the percentage volume of the PTV receiving 24 Gy compared with 3D-CRT (93.5% vs. 84.8%; p = 0.007), while keeping target homogeneity equivalent to 3D-CRT (p = 0.869). The absolute percentage reduction in the irradiated volume of the normal brain receiving 100%, 75%, 50%, and 25% of 24 Gy ranged from 0.7% to 16.0% in IMRT compared with 3D-CRT (p < 0.001). No significant difference was observed in the volume of the normal brain receiving 10% and 5% of 24 Gy between IMRT and 3D-CRT. Conformation number was significantly improved in IMRT (p < 0.001). For other OARs, the mean dose to the cochlea was reduced significantly in IMRT by 22.3% of 24 Gy compared with 3D-CRT (p < 0.001). Conclusions: Compared with 3D-CRT, IMRT for WV improved the target coverage and reduced the irradiated volume of the normal brain in patients with intracranial germinomas receiving induction chemotherapy. IMRT for WV with induction chemotherapy could reduce the late side effects from cranial irradiation without compromising control of the tumor.« less

Estimating radiotherapy demands in South East Asia countries in 2025 and 2035 using evidence-based optimal radiotherapy fractions.

PubMed

Yahya, Noorazrul; Roslan, Nurhaziqah

2018-01-08

As about 50% of cancer patients may require radiotherapy, the demand of radiotherapy as the main treatment to treat cancer is likely to rise due to rising cancer incidence. This study aims to quantify the radiotherapy demand in countries in Southeast Asia (SEA) in 2025 and 2035 using evidence-based optimal radiotherapy fractions. SEA country-specific cancer incidence by tumor site for 2015, 2025 and 2035 was extracted from the GLOBOCAN database. We utilized the optimal radiotherapy utilization rate model by Wong et al. (2016) to calculate the optimal number of fractions for all tumor sites in each SEA country. The available machines (LINAC & Co-60) were extracted from the IAEA's Directory of Radiotherapy Centres (DIRAC) from which the number of available fractions was calculated. The incidence of cancers in SEA countries are expected to be 1.1 mil cases (2025) and 1.4 mil (2035) compared to 0.9 mil (2015). The number of radiotherapy fractions needed in 2025 and 2035 are 11.1 and 14.1 mil, respectively, compared to 7.6 mil in 2015. In 2015, the radiotherapy fulfillment rate (RFR; required fractions/available fractions) varied between countries with Brunei, Singapore and Malaysia are highest (RFR > 1.0 - available fractions > required fractions), whereas Cambodia, Indonesia, Laos, Myanmar, Philippines, Timor-Leste and Vietnam have RFR < 0.5. RFR is correlated to GDP per capita (ρ = 0.73, P = 0.01). To allow RFR ≥1 in 2025 and 2035, another 866 and 1177 machines are required, respectively. The number are lower if longer running hours are implemented. With the optimal number of radiotherapy fractions, estimation for number of machines required can be obtained which will guide acquisition of machines in SEA countries. RFR is low with access varied based on the economic status. © 2018 John Wiley & Sons Australia, Ltd.

Phase II multi-institutional clinical trial on a new mixed beam RT scheme of IMRT on pelvis combined with a carbon ion boost for high-risk prostate cancer patients.

PubMed

Marvaso, Giulia; Jereczek-Fossa, Barbara A; Vischioni, Barbara; Ciardo, Delia; Giandini, Tommaso; Hasegawa, Azusa; Cattani, Federica; Carrara, Mauro; Ciocca, Mario; Bedini, Nice; Villa, Sergio; Morlino, Sara; Russo, Stefania; Zerini, Dario; Colangione, Sarah Pia; Panaino, Costanza Maria Vittoria; Fodor, Cristiana; Santoro, Luigi; Pignoli, Emanuele; Valvo, Francesca; Valdagni, Riccardo; De Cobelli, Ottavio; Orecchia, Roberto

2017-05-12

Definition of the optimal treatment schedule for high-risk prostate cancer is under debate. A combination of photon intensity modulated radiotherapy (IMRT) on pelvis with a carbon ion boost might be the optimal treatment scheme to escalate the dose on prostate and deliver curative dose with respect to normal tissue and quality of dose distributions. In fact, carbon ion beams offer the advantage to deliver hypofractionated radiotherapy (RT) using a significantly smaller number of fractions compared to conventional RT without increasing risks of late effects. This study is a prospective phase II clinical trial exploring safety and feasibility of a mixed beam scheme of carbon ion prostate boost followed by photon IMRT on pelvis. The study is designed to enroll 65 patients with localized high-risk prostate cancer at 3 different oncologic hospitals: Istituto Europeo di Oncologia, Fondazione IRCCS Istituto Nazionale dei Tumori, and Centro Nazionale di Adroterapia Oncologica. The primary endpoint is the evaluation of safety and feasibility with acute toxicity scored up to 1 month after the end of RT. Secondary endpoints are treatment early (3 months after the end of RT) and long-term tolerability, quality of life, and efficacy. The study is not yet recruiting; in silico studies are ongoing and we expect to start recruitment by 2017. The present clinical trial aims at improving the current treatment for high-risk prostate cancer, evaluating safety and feasibility of a new RT mixed-beam scheme including photons and carbon ions. Encouraging results are coming from carbon ion facilities worldwide on the treatment of different tumors including prostate cancers. Carbon ions combine physical properties allowing for high dose conformity and advantageous radiobiological characteristics. The proposed mixed beam treatment has the advantage to combine a photon high conformity standard of care IMRT phase with a hypofractionated carbon ion RT boost delivered in a short overall treatment time.

Initial Results from the Royal College of Radiologists' UK National Audit of Anal Cancer Radiotherapy 2015.

PubMed

Muirhead, R; Drinkwater, K; O'Cathail, S M; Adams, R; Glynne-Jones, R; Harrison, M; Hawkins, M A; Sebag-Montefiore, D; Gilbert, D C

2017-03-01

UK guidance was recently developed for the treatment of anal cancer using intensity-modulated radiotherapy (IMRT). We audited the current use of radiotherapy in UK cancer centres for the treatment of anal cancer against such guidance. We describe the acute toxicity of IMRT in comparison with patient population in the audit treated with two-phase conformal radiotherapy and the previous published data from two-phase conformal radiotherapy, in the UK ACT2 trial. A Royal College of Radiologists' prospective national audit of patients treated with radiotherapy in UK cancer centres was carried out over a 6 month period between February and July 2015. Two hundred and forty-two cases were received from 40/56 cancer centres (71%). In total, 231 (95%) underwent full dose radiotherapy with prophylactic nodal irradiation. Of these, 180 (78%) received IMRT or equivalent, 52 (22%) two-phase conformal (ACT2) technique. The number of interruptions in radiotherapy treatment in the ACT2 trial was 15%. Interruptions were noted in 7% (95% confidence interval 0-14%) of courses receiving two-phase conformal and 4% (95% confidence interval 1-7%) of those receiving IMRT. The percentage of patients completing the planned radiotherapy dose, irrelevant of gaps, was 90% (95% confidence interval 82-98%) and 96% (95% confidence interval 93-99%), in two-phase conformal and IMRT respectively. The toxicity reported in the ACT2 trial, in patients receiving two-phase conformal in the audit and in patients receiving IMRT in the audit was: any toxic effect 71%, 54%, 48%, non-haematological 62%, 49%, 40% and haematological 26%, 13%, 18%, respectively. IMRT implementation for anal cancer is well underway in the UK with most patients receiving IMRT delivery, although its usage is not yet universal. This audit confirms that IMRT results in reduced acute toxicity and minimised treatment interruptions in comparison with previous two-phase conformal techniques. Copyright © 2016 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

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

Chen, Allen M.; Daly, Megan E.; Bucci, M. Kara

Purpose: To compare clinical outcomes of patients with carcinomas of the paranasal sinuses and nasal cavity according to decade of radiation treatment. Methods and Materials: Between 1960 and 2005, 127 patients with sinonasal carcinoma underwent radiotherapy with planning and delivery techniques available at the time of treatment. Fifty-nine patients were treated by conventional radiotherapy; 45 patients by three-dimensional conformal radiotherapy; and 23 patients by intensity-modulated radiotherapy. Eighty-two patients (65%) were treated with radiotherapy after gross total tumor resection. Nineteen patients (15%) received chemotherapy. The most common histology was squamous cell carcinoma (83 patients). Results: The 5-year estimates of overall survival,more » local control, and disease-free survival for the entire patient population were 52%, 62%, and 54%, respectively. There were no significant differences in any of these endpoints with respect to decade of treatment or radiotherapy technique (p > 0.05, for all). The 5-year overall survival rate for patients treated in the 1960s, 1970s, 1980s, 1990s, and 2000s was 46%, 56%, 51%, 53%, and 49%, respectively (p = 0.23). The observed incidence of severe (Grade 3 or 4) late toxicity was 53%, 45%, 39%, 28%, and 16% among patients treated in the 1960s, 1970s, 1980s, 1990s, and 2000s, respectively (p = 0.01). Conclusion: Although we did not detect improvements in disease control or overall survival for patients treated over time, the incidence of complications has significantly declined, thereby resulting in an improved therapeutic ratio for patients with carcinomas of the paranasal sinuses and nasal cavity.« less

The impact of technology diffusion on treatment for prostate cancer.

PubMed

Schroeck, Florian R; Kaufman, Samuel R; Jacobs, Bruce L; Zhang, Yun; Weizer, Alon Z; Montgomery, Jeffrey S; Gilbert, Scott M; Strope, Seth A; Hollenbeck, Brent K

2013-12-01

The use of local therapy for prostate cancer may increase because of the perceived advantages of new technologies such as intensity-modulated radiotherapy (IMRT) and robotic prostatectomy. To examine the association of market-level technological capacity with receipt of local therapy. Retrospective cohort. Patients with localized prostate cancer who were diagnosed between 2003 and 2007 (n=59,043) from the Surveillance Epidemiology and End Results-Medicare database. We measured the capacity for delivering treatment with new technology as the number of providers offering robotic prostatectomy or IMRT per population in a market (hospital referral region). The association of this measure with receipt of prostatectomy, radiotherapy, or observation was examined with multinomial logistic regression. For each 1000 patients diagnosed with prostate cancer, 174 underwent prostatectomy, 490 radiotherapy, and 336 were observed. Markets with high robotic prostatectomy capacity had higher use of prostatectomy (146 vs. 118 per 1000 men, P=0.008) but a trend toward decreased use of radiotherapy (574 vs. 601 per 1000 men, P=0.068), resulting in a stable rate of local therapy. High versus low IMRT capacity did not significantly impact the use of prostatectomy (129 vs. 129 per 1000 men, P=0.947) and radiotherapy (594 vs. 585 per 1000 men, P=0.579). Although there was a small shift from radiotherapy to prostatectomy in markets with high robotic prostatectomy capacity, increased capacity for both robotic prostatectomy and IMRT did not change the overall rate of local therapy. Our findings temper concerns that the new technology spurs additional therapy of prostate cancer.

Analysis of Factors Influencing the Development of Xerostomia during Intensity-Modulated Radiotherapy

PubMed Central

Randall, Ken; Stevens, Jason; Yepes, Juan Fernando; Randall, Marcus E.; Kudrimoti, Mahesh; Feddock, Jonathan; Xi, Jing; Kryscio, Richard J.; Miller, Craig S.

2013-01-01

OBJECTIVES Factors influencing xerostomia during intensity-modulated radiation therapy (IMRT) were assessed. METHODS A 6-week study of 32 head and neck cancer (HNC) patients was performed. Subjects completed the Xerostomia Inventory (XI) and provided stimulated saliva (SS) at baseline, week two and at end of IMRT. Influence of SS flow rate (SSFR), calcium and mucin 5b (MUC5b) concentrations and radiation dose on xerostomia was determined. RESULTS HNC subjects experienced mean SSFR decline of 36% by visit two (N=27; p=0.012) and 57% by visit three (N=20; p=0.0004), Concentrations of calcium and MUC5b increased, but not significantly during IMRT (p>0.05). Xerostomia correlated most with decreasing salivary flow rate as determined by Spearman correlations (p<0.04) and linear mixed models (p<0.0001). CONCLUSIONS Although IMRT is sparing to the parotid glands, it has an early effect on SSFR and the constituents in saliva in a manner that is associated with the perception of xerostomia. PMID:23523462

Tomotherapy as a tool in image-guided radiation therapy (IGRT): current clinical experience and outcomes

PubMed Central

Yartsev, S; Kron, T; Van Dyk, J

2007-01-01

Modern radiotherapy is characterised by a better target definition through medical imaging accompanied by significantly improved radiation delivery methods, most notably Intensity-Modulate Radiation Therapy (IMRT). However, the treatment can only be as accurate as the positioning of patients for their daily radiotherapy fraction. It is in this context that a number of imaging modalities - ranging from ultrasound to on-board kilovoltage imaging and computed tomography (CT) - have found their way into the treatment room where they verify accurate patient positioning prior to or even during delivery of radiation. Helical tomotherapy (HT) combines IMRT delivery with in-built image guidance using megavoltage CT scanning. This paper discusses the initial experience of different centres with IGRT using HT illustrated by a number of clinical examples from the installation in London in Ontario, Canada, one of the world’s first HT sites. We found that HT allows the delivery of highly conformal radiation dose distributions combined with adequate daily image acquisition. An important feature of this unit is its seamless integration, which also includes a customised inverse treatment planning system and a quality assurance module for individual patients. PMID:21614258

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

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

Cai, Jinfeng; Cao, Ruifen; Dai, Yumei

Purpose: To build a Monte Carlo dose verification tool for IMRT Plan by implementing a irradiation source model into DPM code. Extend the ability of DPM to calculate any incident angles and irregular-inhomogeneous fields. Methods: With the virtual source and the energy spectrum which unfolded from the accelerator measurement data,combined with optimized intensity maps to calculate the dose distribution of the irradiation irregular-inhomogeneous field. The irradiation source model of accelerator was substituted by a grid-based surface source. The contour and the intensity distribution of the surface source were optimized by ARTS (Accurate/Advanced Radiotherapy System) optimization module based on the tumormore » configuration. The weight of the emitter was decided by the grid intensity. The direction of the emitter was decided by the combination of the virtual source and the emitter emitting position. The photon energy spectrum unfolded from the accelerator measurement data was adjusted by compensating the contaminated electron source. For verification, measured data and realistic clinical IMRT plan were compared with DPM dose calculation. Results: The regular field was verified by comparing with the measured data. It was illustrated that the differences were acceptable (<2% inside the field, 2–3mm in the penumbra). The dose calculation of irregular field by DPM simulation was also compared with that of FSPB (Finite Size Pencil Beam) and the passing rate of gamma analysis was 95.1% for peripheral lung cancer. The regular field and the irregular rotational field were all within the range of permitting error. The computing time of regular fields were less than 2h, and the test of peripheral lung cancer was 160min. Through parallel processing, the adapted DPM could complete the calculation of IMRT plan within half an hour. Conclusion: The adapted parallelized DPM code with irradiation source model is faster than classic Monte Carlo codes. Its computational accuracy and speed satisfy the clinical requirement, and it is expectable to be a Monte Carlo dose verification tool for IMRT Plan. Strategic Priority Research Program of the China Academy of Science(XDA03040000); National Natural Science Foundation of China (81101132)« less

Quality assurance of radiotherapy in cancer treatment: toward improvement of patient safety and quality of care.

PubMed

Ishikura, Satoshi

2008-11-01

The process of radiotherapy (RT) is complex and involves understanding of the principles of medical physics, radiobiology, radiation safety, dosimetry, radiation treatment planning, simulation and interaction of radiation with other treatment modalities. Each step in the integrated process of RT needs quality control and quality assurance (QA) to prevent errors and to give high confidence that patients will receive the prescribed treatment correctly. Recent advances in RT, including intensity-modulated and image-guided RT, focus on the need for a systematic RTQA program that balances patient safety and quality with available resources. It is necessary to develop more formal error mitigation and process analysis methods, such as failure mode and effect analysis, to focus available QA resources optimally on process components. External audit programs are also effective. The International Atomic Energy Agency has operated both an on-site and off-site postal dosimetry audit to improve practice and to assure the dose from RT equipment. Several countries have adopted a similar approach for national clinical auditing. In addition, clinical trial QA has a significant role in enhancing the quality of care. The Advanced Technology Consortium has pioneered the development of an infrastructure and QA method for advanced technology clinical trials, including credentialing and individual case review. These activities have an impact not only on the treatment received by patients enrolled in clinical trials, but also on the quality of treatment administered to all patients treated in each institution, and have been adopted globally; by the USA, Europe and Japan also.

Development and operation of a pixel segmented liquid-filled linear array for radiotherapy quality assurance.

PubMed

Pardo, J; Franco, L; Gómez, F; Iglesias, A; Pazos, A; Pena, J; Lobato, R; Mosquera, J; Pombar, M; Sendón, J

2005-04-21

A liquid isooctane (C(8)H(18)) filled ionization linear array for radiotherapy quality assurance has been designed, built and tested. The detector consists of 128 pixels, each of them with an area of 1.7 mm x 1.7 mm and a gap of 0.5 mm. The small pixel size makes the detector ideal for high gradient beam profiles such as those present in intensity modulated radiation therapy (IMRT) and radiosurgery. As the read-out electronics we use the X-ray Data Acquisition System with the Xchip developed by the CCLRC. Studies concerning the collection efficiency dependence on the polarization voltage and on the dose rate have been made in order to optimize the device operation. In the first tests, we have studied dose rate and energy dependences. Dose rate dependence was found to be lower than 2.1% up to 5 Gy min(-1), and energy dependence lower than 2.5% up to 20 cm depth in solid water. Output factors and penumbras for several rectangular fields have been measured with the linear array and were compared with the results obtained with a 0.125 cm(3) air ionization chamber and radiographic film, respectively. Finally, we have acquired profiles for an IMRT field and for a virtual wedge. These profiles have also been compared with radiographic film measurements. All the comparisons show a good correspondence. The device has proved its capability to verify on-line therapy beams with good spatial resolution and signal-to-noise ratio.

Head and Neck Cancers: Advantages of Advanced Radiation Therapy and Importance of Supportive Care.

PubMed

Spencer, Sharon

2018-05-01

For more than a decade, the incidence of head and neck cancers has been increasing in the United States. Worldwide, they are the ninth most common cancer. Today, newer advances in radiotherapy (RT), such as fractionation, 4-dimensional cone-beam CT, and intensity-modulated RT, have provided clinicians with the opportunity for improved patient outcomes. At the NCCN 23rd Annual Conference, Sharon Spencer, MD, described the advantages of advances in RT and the means to mitigate untoward side effects. Copyright © 2018 by the National Comprehensive Cancer Network.

Malignant Pleural Mesothelioma

PubMed Central

Tsao, Anne S.; Wistuba, Ignacio; Roth, Jack A.; Kindler, Hedy Lee

2009-01-01

Malignant pleural mesothelioma (MPM) is a deadly disease that occurs in 2,000 to 3,000 people each year in the United States. Although MPM is an extremely difficult disease to treat, with the median overall survival ranging between 9 and 17 months regardless of stage, there has been significant progress over the last few years that has reshaped the clinical landscape. This article will provide a comprehensive discussion of the latest developments in the treatment of MPM. We will provide an update of the major clinical trials that impact mesothelioma treatment in the resectable and unresectable settings, discuss the impact of novel therapeutics, and provide perspective on where the clinical research in mesothelioma is moving. In addition, there are controversial issues, such as the role of extrapleural pneumonectomy, adjuvant radiotherapy, and use of intensity-modulated radiotherapy versus hemithoracic therapy that will also be addressed in this manuscript. PMID:19255316

Real-time detection of fast and thermal neutrons in radiotherapy with CMOS sensors.

PubMed

Arbor, Nicolas; Higueret, Stephane; Elazhar, Halima; Combe, Rodolphe; Meyer, Philippe; Dehaynin, Nicolas; Taupin, Florence; Husson, Daniel

2017-03-07

The peripheral dose distribution is a growing concern for the improvement of new external radiation modalities. Secondary particles, especially photo-neutrons produced by the accelerator, irradiate the patient more than tens of centimeters away from the tumor volume. However the out-of-field dose is still not estimated accurately by the treatment planning softwares. This study demonstrates the possibility of using a specially designed CMOS sensor for fast and thermal neutron monitoring in radiotherapy. The 14 microns-thick sensitive layer and the integrated electronic chain of the CMOS are particularly suitable for real-time measurements in γ/n mixed fields. An experimental field size dependency of the fast neutron production rate, supported by Monte Carlo simulations and CR-39 data, has been observed. This dependency points out the potential benefits of a real-time monitoring of fast and thermal neutron during beam intensity modulated radiation therapies.

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

Ureba, A.; Salguero, F. J.; Barbeiro, A. R.

Purpose: The authors present a hybrid direct multileaf collimator (MLC) aperture optimization model exclusively based on sequencing of patient imaging data to be implemented on a Monte Carlo treatment planning system (MC-TPS) to allow the explicit radiation transport simulation of advanced radiotherapy treatments with optimal results in efficient times for clinical practice. Methods: The planning system (called CARMEN) is a full MC-TPS, controlled through aMATLAB interface, which is based on the sequencing of a novel map, called “biophysical” map, which is generated from enhanced image data of patients to achieve a set of segments actually deliverable. In order to reducemore » the required computation time, the conventional fluence map has been replaced by the biophysical map which is sequenced to provide direct apertures that will later be weighted by means of an optimization algorithm based on linear programming. A ray-casting algorithm throughout the patient CT assembles information about the found structures, the mass thickness crossed, as well as PET values. Data are recorded to generate a biophysical map for each gantry angle. These maps are the input files for a home-made sequencer developed to take into account the interactions of photons and electrons with the MLC. For each linac (Axesse of Elekta and Primus of Siemens) and energy beam studied (6, 9, 12, 15 MeV and 6 MV), phase space files were simulated with the EGSnrc/BEAMnrc code. The dose calculation in patient was carried out with the BEAMDOSE code. This code is a modified version of EGSnrc/DOSXYZnrc able to calculate the beamlet dose in order to combine them with different weights during the optimization process. Results: Three complex radiotherapy treatments were selected to check the reliability of CARMEN in situations where the MC calculation can offer an added value: A head-and-neck case (Case I) with three targets delineated on PET/CT images and a demanding dose-escalation; a partial breast irradiation case (Case II) solved with photon and electron modulated beams (IMRT + MERT); and a prostatic bed case (Case III) with a pronounced concave-shaped PTV by using volumetric modulated arc therapy. In the three cases, the required target prescription doses and constraints on organs at risk were fulfilled in a short enough time to allow routine clinical implementation. The quality assurance protocol followed to check CARMEN system showed a high agreement with the experimental measurements. Conclusions: A Monte Carlo treatment planning model exclusively based on maps performed from patient imaging data has been presented. The sequencing of these maps allows obtaining deliverable apertures which are weighted for modulation under a linear programming formulation. The model is able to solve complex radiotherapy treatments with high accuracy in an efficient computation time.« less

Optimizing the induction chemotherapy regimen for patients with locoregionally advanced nasopharyngeal Carcinoma: A big-data intelligence platform-based analysis.

PubMed

Peng, Hao; Tang, Ling-Long; Chen, Bin-Bin; Chen, Lei; Li, Wen-Fei; Mao, Yan-Ping; Liu, Xu; Zhang, Yuan; Liu, Li-Zhi; Tian, Li; Guo, Ying; Sun, Ying; Ma, Jun

2018-04-01

This study aimed at identifying the optimal induction chemotherapy regimen for patients with locoregionally advanced nasopharyngeal carcinoma (NPC) treated by intensity-modulated radiotherapy. We identified eligible patients with newly-diagnosed stage III-IVA NPC (excluding T3N0) between September 2009 and May 2015. Survival outcomes and grade 3-4 toxicities were compared between different IC regimen groups. In total, 3738 patients were eligible for this study, with 1572 (42.1%), 1085 (29.0%) and 1081 (28.9%) receiving TPF, PF and TP, respectively. In the whole population, multivariate analysis found that TPF seems to be better than PF and TP. Howerver, subgroup analysis revealed TPF and TP had same effectiveness in patients receiving a cumulative cisplatin dose (CCD) ≥200mg/m 2 in concurrent chemotherapy, while TPF shows relatively better survival benefit in patients receiving CCD<200mg/m 2 . Grade 3-4 toxicities were similar between TPF and TP groups, but were relatively higher than that in PF group. Our study concluded that induction TP regimen may be enough for patients receiving a CCD≥200mg/m 2 , while TPF may be superior to TP and PF for patients receiving a CCD<200mg/m 2 , although grade 3-4 toxic events were more common but tolerable. Further studies are needed to validate our findings. Copyright © 2018 Elsevier Ltd. All rights reserved.

New 2-D dosimetric technique for radiotherapy based on planar thermoluminescent detectors.

PubMed

Olko, P; Marczewska, B; Czopyk, L; Czermak, M A; Klosowski, M; Waligórski, M P R

2006-01-01

At the Institute of Nuclear Physics of the Polish Academy of Sciences (IFJ) in Kraków, a two-dimensional (2-D) thermoluminescence (TL) dosimetry system was developed within the MAESTRO (Methods and Advanced Equipment for Simulation and Treatment in Radio-Oncology) 6 Framework Programme and tested by evaluating 2-D dose distributions around radioactive sources. A thermoluminescent detector (TLD) foil was developed, of thickness 0.3 mm and diameter 60 mm, containing a mixture of highly sensitive LiF:Mg,Cu,P powder and Ethylene TetraFluoroEthylene (ETFE) polymer. Foil detectors were irradiated with (226)Ra brachytherapy sources and a (90)Sr/(90)Y source. 2-D dose distributions were evaluated using a prototype planar (diameter 60 mm) reader, equipped with a 12 bit Charge Coupled Devices (CCD) PCO AG camera, with a resolution of 640 x 480 pixels. The new detectors, showing a spatial resolution better than 0.5 mm and a measurable dose range typical for radiotherapy, can find many applications in clinical dosimetry. Another technology applicable to clinical dosimetry, also developed at IFJ, is the Si microstrip detector of size 95 x 95 mm(2), which may be used to evaluate the dose distribution with a spatial resolution of 120 microm along one direction, in real-time mode. The microstrip and TLD technology will be further improved, especially to develop detectors of larger area, and to make them applicable to some advanced radiotherapy modalities, such as intensity modulated radiotherapy (IMRT) or proton radiotherapy.

Upper cervical spine chordoma of C2–C3

PubMed Central

Jiang, Liang; Liu, Xiao Guang; Ma, Qing Jun; Wei, Feng; Lv, Yang; Dang, Geng Ting

2009-01-01

Chordoma is a rare low-grade malignant neoplasm derived from the remnants of the embryonic notochord. This locally invasive neoplasm is subject to recurrence after treatment. The median survival time is estimated to be 6.3 years. Various treatment approaches have been attempted, including radical excision, radiotherapy and chemotherapy. Treatment outcome is significantly influenced by the size and site of the chordoma. Recently, Imatinib, a molecular-targeted agent, has been shown to have antitumor activity in chordoma. Proton radiotherapy, stereotactic radiotherapy and intensity-modulated radiotherapy have also been used. Surgical treatment is still the primary choice for chordoma. It has become more aggressive in recent years, evolving from intralesional or partial excision to en bloc resection. However, upper cervical localizations make such en bloc resection in most cases not possible. We present and discuss the therapeutic challenges of a young female with large retropharyngeal chordoma who presented to our institution after conventional photon beam radiotherapy. This C2/3 tumor was classified IB according to the Enneking classification. It distributed to layers A–D and sectors 1–6 according to the Weinstein Boriani Biagini Classification. The left vertebral artery (VA) was encapsulated and displaced. One stage intralesional extracapsular tumor excision and reconstruction was achieved by combined bilateral high anterior cervical approaches and posterior approach. No recurrence or metastasis was observed 3 years after the operation. She returned to her previous occupation as office worker. PMID:19221808

Effect of Cisplatin on Parotid Gland Function in Concomitant Radiochemotherapy

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

Hey, Jeremias; Setz, Juergen; Gerlach, Reinhard

2009-12-01

Purpose: To determine the influence of concomitant radiochemotherapy with cisplatin on parotid gland tissue complication probability. Methods and Materials: Patients treated with either radiotherapy (n = 61) or concomitant radiochemotherapy with cisplatin (n = 36) for head-and-neck cancer were prospectively evaluated. The dose and volume distributions of the parotid glands were noted in dose-volume histograms. Stimulated salivary flow rates were measured before, during the 2nd and 6th weeks and at 4 weeks and 6 months after the treatment. The data were fit using the normal tissue complication probability model of Lyman. Complication was defined as a reduction of the salivarymore » flow rate to less than 25% of the pretreatment flow rate. Results: The normal tissue complication probability model parameter TD{sub 50} (the dose leading to a complication probability of 50%) was found to be 32.2 Gy at 4 weeks and 32.1 Gy at 6 months for concomitant radiochemotherapy and 41.1 Gy at 4 weeks and 39.6 Gy at 6 months for radiotherapy. The tolerated dose for concomitant radiochemotherapy was at least 7 to 8 Gy lower than for radiotherapy alone at TD{sub 50}. Conclusions: In this study, the concomitant radiochemotherapy tended to cause a higher probability of parotid gland tissue damage. Advanced radiotherapy planning approaches such as intensity-modulated radiotherapy may be partiticularly important for parotid sparing in radiochemotherapy because of cisplatin-related increased radiosensitivity of glands.« less

Estimation of the optimal number of radiotherapy fractions for breast cancer: A review of the evidence.

PubMed

Wong, Karen; Delaney, Geoff P; Barton, Michael B

2015-08-01

There is variation in radiotherapy fractionation practice, however, there is no evidence-based benchmark for appropriate activity. An evidence-based model was constructed to estimate the optimal number of fractions for the first course of radiotherapy for breast cancer to aid in services planning and performance benchmarking. The published breast cancer radiotherapy utilisation model was adapted. Evidence-based number of fractions was added to each radiotherapy indication. The overall optimal number of fractions was calculated based on the frequency of specific clinical conditions where radiotherapy is indicated and the recommended number of fractions for each condition. Sensitivity analysis was performed to assess the impact of uncertainties on the model. For the entire Australian breast cancer patient population, the estimated optimal number of fractions per patient was 16.8, 14.6, 13.7 and 0.8 for ductal carcinoma in situ, early, advanced and metastatic breast cancer respectively. Overall, the optimal number of fractions per patient was 14.4 (range 14.4-18.7). These results allow comparison with actual practices, and workload prediction to aid in services planning. The model can be easily adapted to other countries by inserting population-specific epidemiological data, and to future changes in cancer incidence, stage distribution and fractionation recommendations. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Optimal spiral phase modulation in Gerchberg-Saxton algorithm for wavefront reconstruction and correction

NASA Astrophysics Data System (ADS)

Baránek, M.; Běhal, J.; Bouchal, Z.

2018-01-01

In the phase retrieval applications, the Gerchberg-Saxton (GS) algorithm is widely used for the simplicity of implementation. This iterative process can advantageously be deployed in the combination with a spatial light modulator (SLM) enabling simultaneous correction of optical aberrations. As recently demonstrated, the accuracy and efficiency of the aberration correction using the GS algorithm can be significantly enhanced by a vortex image spot used as the target intensity pattern in the iterative process. Here we present an optimization of the spiral phase modulation incorporated into the GS algorithm.

Controlled generation of high-intensity optical rogue waves by induced modulation instability

PubMed Central

Zhao, Saili; Yang, Hua; Chen, Nengsong; Zhao, Chujun

2017-01-01

Optical rogue waves are featured as the generation of high amplitude events at low probability in optical systems. Moreover, the formation of optical rogue waves is unpredictable and transient in photonic crystal fibers. In this paper, we put forward a method to generate high-intensity optical rogue waves in a more controlled way based on induced modulation instability, which can suppress the noise effect and hence play a leading role in the process of pulse evolution. Our numerical simulations indicate that the generation of rogue wave can be controlled when seeding at the optimal modulation frequency and the intensity of rogue wave can be enhanced with appropriate modulation depth. Further, high-intensity rogue wave can also be ejected in the fiber with a shorter propagation length by regulating the modulation depth. These results all provide a better understanding of optical rogue wave, which can contribute to the generation of tunable long-wavelength spectral components and selective excitation of mid-infrared supercontinuum. PMID:28051149

Controlled generation of high-intensity optical rogue waves by induced modulation instability.

PubMed

Zhao, Saili; Yang, Hua; Chen, Nengsong; Zhao, Chujun

2017-01-04

Optical rogue waves are featured as the generation of high amplitude events at low probability in optical systems. Moreover, the formation of optical rogue waves is unpredictable and transient in photonic crystal fibers. In this paper, we put forward a method to generate high-intensity optical rogue waves in a more controlled way based on induced modulation instability, which can suppress the noise effect and hence play a leading role in the process of pulse evolution. Our numerical simulations indicate that the generation of rogue wave can be controlled when seeding at the optimal modulation frequency and the intensity of rogue wave can be enhanced with appropriate modulation depth. Further, high-intensity rogue wave can also be ejected in the fiber with a shorter propagation length by regulating the modulation depth. These results all provide a better understanding of optical rogue wave, which can contribute to the generation of tunable long-wavelength spectral components and selective excitation of mid-infrared supercontinuum.

Dosimetric Comparison between Single and Dual Arc-Volumetric Modulated Arc Radiotherapy and Intensity Modulated Radiotherapy for Nasopharyngeal Carcinoma Using a Simultaneous Integrated Boost Technique

PubMed Central

Radhakrishnan, Sivakumar; Chandrasekaran, Anuradha; Sarma, Yugandhar; Balakrishnan, Saranganathan; Nandigam, Janardhan

2017-01-01

Backround: Plan quality and performance of dual arc (DA) volumetric modulated arc therapy (VMAT), single arc (SA) VMAT and nine field (9F) intensity modulated radiotherapy were compared using a simultaneous integrated boost (SIB) technique. Methods: Twelve patients treated in Elekta Synergy Platform (mlci2) by 9F-IMRT were replanned with SA/DA-VMAT using a CMS Monaco Treatment Planning System (TPS) with Monte Carlo simulation. Target delineation was conducted as per Radiation Therapy Oncology Protocols (RTOG0225 and 0615). A 70Gy dose prescribed to PTV70 and 61Gy to PTV61 in 33 fractions was applied for the SIB technique. The conformity index (CI) and homogeneity index (HI) for targets and the mean dose and maximum dose for OAR’s, treatment delivery time (min), monitor units (MUs) per fraction, normal tissue integral dose and patient specific quality assurance were analysed. Results: Acceptable target coverage was achieved for PTV70 and PTV61 with all the planning techniques. No significant differences were observed except for D98 (PTV61), CI(PTV70) and HI(PTV61). Maximum dose (Dmax) to the spinal cord was lower in DA-VMAT than 9F-IMRT (p=0.002) and SA-VMAT (p=0.001). D50 (%) of parotid glands was better controlled by 9F-IMRT (p=0.001) and DA-VMAT (p=0.001) than SA-VMAT. A lower mean dose to the larynx was achieved with 9F-IMRT (P=0.001) and DA-VMAT (p=0.001) than with SA-VMAT. DA-VMAT achieved higher CI of PTV70 (P= 0.005) than SA-VMAT. For PTV61, DA-VMAT (P=0.001) and 9F-IMRT (P=0.001) achieved better HI than SA-VMAT. The average treatment delivery times were 7.67mins, 3.35 mins, 4.65 mins for 9F-IMRT, SA-VMAT and DA-VMAT, respectively. No significant difference were observed in MU/fr (p=0.9) and NTID (P=0.90) and the patient quality assurance pass rates were >95% (gamma analysis I3mm, 3%). Conclusion: DA-VMAT showed better conformity over target dose and spared the OARs better or equal to IMRT. SA-VMAT could not spare the OARs well. DA-VMAT offered shorter delivery time than IMRT without compromising the plan quality. PMID:28612593

Dosimetric Comparison between Single and Dual Arc-Volumetric Modulated Arc Radiotherapy and Intensity Modulated Radiotherapy for Nasopharyngeal Carcinoma Using a Simultaneous Integrated Boost Technique

PubMed

Radhakrishnan, Sivakumar; Chandrasekaran, Anuradha; Sarma, Yugandhar; Balakrishnan, Saranganathan; Nandigam, Janardhan

2017-05-01

Backround: Plan quality and performance of dual arc (DA) volumetric modulated arc therapy (VMAT) , single arc (SA) VMAT and nine field (9F) intensity modulated radiotherapy were compared using a simultaneous integrated boost (SIB) technique. Methods: Twelve patients treated in Elekta Synergy Platform (mlci2) by 9F-IMRT were replanned with SA/DA-VMAT using a CMS Monaco Treatment Planning System (TPS) with Monte Carlo simulation. Target delineation was conducted as per Radiation Therapy Oncology Protocols (RTOG0225 and 0615). A 70Gy dose prescribed to PTV70 and 61Gy to PTV61 in 33 fractions was applied for the SIB technique. The conformity index (CI) and homogeneity index (HI) for targets and the mean dose and maximum dose for OAR’s, treatment delivery time (min), monitor units (MUs) per fraction, normal tissue integral dose and patient specific quality assurance were analysed. Results: Acceptable target coverage was achieved for PTV70 and PTV61 with all the planning techniques. No significant differences were observed except for D98 (PTV61), CI(PTV70) and HI(PTV61). Maximum dose (Dmax) to the spinal cord was lower in DA-VMAT than 9F-IMRT (p=0.002) and SA-VMAT (p=0.001). D50 (%) of parotid glands was better controlled by 9F-IMRT (p=0.001) and DA-VMAT (p=0.001) than SA-VMAT. A lower mean dose to the larynx was achieved with 9F-IMRT (P=0.001) and DA-VMAT (p=0.001) than with SA-VMAT. DA-VMAT achieved higher CI of PTV70 (P= 0.005) than SA-VMAT. For PTV61, DA-VMAT (P=0.001) and 9F-IMRT (P=0.001) achieved better HI than SA-VMAT. The average treatment delivery times were 7.67mins, 3.35 mins, 4.65 mins for 9F- IMRT, SA-VMAT and DA-VMAT, respectively. No significant difference were observed in MU/fr (p=0.9) and NTID (P=0.90) and the patient quality assurance pass rates were >95% (gamma analysis Ґ3mm, 3%). Conclusion: DA-VMAT showed better conformity over target dose and spared the OARs better or equal to IMRT. SA-VMAT could not spare the OARs well. DA-VMAT offered shorter delivery time than IMRT without compromising the plan quality. Creative Commons Attribution License

The importance of prostate bed tilt during postprostatectomy intensity-modulated radiotherapy

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

Bell, Linda J., E-mail: Linda.Bell1@health.nsw.gov.au; Faculty of Health Sciences, University of Sydney, Lidcombe, New South Wales; Cox, Jennifer

2014-10-01

Variations in rectal and bladder filling can create a tilt of the prostate bed, which generates the potential for a geographic miss during postprostatectomy radiotherapy. The aim of this study is to assess the effect that bladder and rectum filling has on planning target volume angle, to determine a method to assess prostate bed tilt leading to potential geographic miss, and to discuss possible implementation issues. The cone-beam computed tomography images (n = 377) of 40 patients who received postprostatectomy radiotherapy with intensity-modulated radiotherapy were reviewed. The amount of tilt in the prostate bed was defined as the angle changemore » between 2 surgical clips, one in the upper prostate bed and another in the lower. A potential geographic miss was defined as movement of any clip of more than 1 cm in any direction or 0.5 cm posteriorly when aligned to bone anatomy. Variations in bladder and rectum size were correlated with the degree of prostate bed tilt, and the rate of potential geographic miss was determined. A possible clinical use of prostate bed tilt was then assessed for different imaging techniques. A tilt of more than 10° was seen in 20.2% of images, which resulted in a 57.9% geographic miss rate of the superior clip. When tilt remained within 10°, there was only a 9% rate of geographic miss. Potential geographic miss of the inferior surgical clip was rare, occurring in only 1.9% of all images reviewed. The most common occurrence when the prostate bed tilt increased by more than 10° was a smaller bladder and larger rectum (6.4% of all images). The most common occurrence when the prostate bed tilt decreased by more than 10° was a larger bladder and smaller rectum (1.3% of all images). Significant prostate bed tilt (>± 10°) occurred in more than 20% of images, creating a 58% rate of geographic miss. Greatest prostate bed tilt occurred when the bladder size increased or reduced by more than 2 cm or the superior rectum size increased by more than 1.5 cm or reduced by more than 1 cm from the planned size. Using prostate bed tilt could be an effective measurement for assessing potential geographic miss on orthogonal images if volumetric imaging is unavailable.« less

High dose hypofractionated frameless volumetric modulated arc radiotherapy is a feasible method for treating canine trigeminal nerve sheath tumors.

PubMed

Dolera, Mario; Malfassi, Luca; Marcarini, Silvia; Mazza, Giovanni; Carrara, Nancy; Pavesi, Simone; Sala, Massimo; Finesso, Sara; Urso, Gaetano

2018-06-08

The aim of this prospective pilot study was to evaluate the feasibility and effectiveness of curative intent high dose hypofractionated frameless volumetric modulated arc radiotherapy for treatment of canine trigeminal peripheral nerve sheath tumors. Client-owned dogs with a presumptive imaging-based diagnosis of trigeminal peripheral nerve sheath tumor were recruited for the study during the period of February 2010 to December 2013. Seven dogs were enrolled and treated with high dose hypofractionated volumetric modulated arc radiotherapy delivered by a 6 MV linear accelerator equipped with a micro-multileaf beam collimator. The plans were computed using a Monte Carlo algorithm with a prescription dose of 37 Gy delivered in five fractions on alternate days. Overall survival was estimated using a Kaplan-Meier curve analysis. Magnetic resonance imaging (MRI) follow-up examinations revealed complete response in one dog, partial response in four dogs, and stable disease in two dogs. Median overall survival was 952 days with a 95% confidence interval of 543-1361 days. Volumetric modulated arc radiotherapy was demonstrated to be feasible and effective for trigeminal peripheral nerve sheath tumor treatment in this sample of dogs. The technique required few sedations and spared organs at risk. Even though larger studies are required, these preliminary results supported the use of high dose hypofractionated volumetric modulated arc radiotherapy as an alternative to other treatment modalities. © 2018 American College of Veterinary Radiology.

Development of three-dimensional radiotherapy techniques in breast cancer

NASA Astrophysics Data System (ADS)

Coles, Charlotte E.

Radiotherapy following conservation surgery decreases local relapse and death from breast cancer. Currently, the challenge is to minimise the morbidity caused by this treatment without losing efficacy. Despite many advances in radiation techniques in other sites of the body, the majority of breast cancer patients are still planned and treated using 2-dimensional simple radiotherapy techniques. In addition, breast irradiation currently consumes 30% of the UK's radiotherapy workload. Therefore, any change to more complex treatment should be of proven benefit. The primary objective of this research is to develop and evaluate novel radiotherapy techniques to decrease irradiation of normal structures and improve localisation of the tumour bed. I have developed a forward-planned intensity modulated (IMRT) breast radiotherapy technique, which has shown improved dosimetry results compared to standard breast radiotherapy. Subsequently, I have developed and implemented a phase III randomised controlled breast IMRT trial. This National Cancer Research Network adopted trial will answer an important question regarding the clinical benefit of breast IMRT. It will provide DNA samples linked with high quality clinical outcome data, for a national translational radiogenomics study investigating variation in normal tissue toxicity. Thus, patients with significant late normal tissue side effects despite good dose homogeneity will provide the best model for finding differences due to underlying genetics. I evaluated a novel technique using high definition free-hand 3-dimensional (3D) ultrasound in a phantom study, and the results suggested that this is an accurate and reproducible method for tumour bed localisation. I then compared recognised methods of tumour bed localisation with the 3D ultrasound method in a clinical study. The 3D ultrasound technique appeared to accurately represent the shape and spatial position of the tumour cavity. This tumour bed localisation research facilitated protocol development of a proposed national breast radiotherapy trial investigating IMRT and partial breast irradiation.

Accounting for range uncertainties in the optimization of intensity modulated proton therapy.

PubMed

Unkelbach, Jan; Chan, Timothy C Y; Bortfeld, Thomas

2007-05-21

Treatment plans optimized for intensity modulated proton therapy (IMPT) may be sensitive to range variations. The dose distribution may deteriorate substantially when the actual range of a pencil beam does not match the assumed range. We present two treatment planning concepts for IMPT which incorporate range uncertainties into the optimization. The first method is a probabilistic approach. The range of a pencil beam is assumed to be a random variable, which makes the delivered dose and the value of the objective function a random variable too. We then propose to optimize the expectation value of the objective function. The second approach is a robust formulation that applies methods developed in the field of robust linear programming. This approach optimizes the worst case dose distribution that may occur, assuming that the ranges of the pencil beams may vary within some interval. Both methods yield treatment plans that are considerably less sensitive to range variations compared to conventional treatment plans optimized without accounting for range uncertainties. In addition, both approaches--although conceptually different--yield very similar results on a qualitative level.

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

PubMed

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

2003-06-01

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

Influence of Cervical Node Necrosis of Different Grades on the Prognosis of Nasopharyngeal Carcinoma Patients Treated with Intensity-Modulated Radiotherapy.

PubMed

Zhang, Lu-Lu; Li, Jia-Xiang; Zhou, Guan-Qun; Tang, Ling-Long; Ma, Jun; Lin, Ai-Hua; Qi, Zhen-Yu; Sun, Ying

2017-01-01

Background: To analyze the prognostic value of cervical node necrosis (CNN) observed on pretreatment magnetic resonance imaging (MRI) in patients with nasopharyngeal carcinoma (NPC) treated with intensity-modulated radiotherapy (IMRT). Patients and Methods: The medical records of 1423 NPC patients with cervical node metastasis who underwent IMRT were retrospectively reviewed. Lymph nodes in the axial plane of pretreatment MRI were classified as follows: grade 0 CNN, no hypodense zones; grade 1 CNN, ≤33% areas showing hypodense zones; and grade 2, >33% areas showing hypodense zones. Results: CNN was detectable in 470/1423 (33%) patients. Of these 470 patients, 213 (15%) and 257 (18%) exhibited grade 1 and grade 2 CNN. The grade 0 and grade 1 CNN groups showed significant differences with regard to distant metastasis-free survival (DMFS), but not overall survival (OS), regional relapse-free survival (RRFS), local relapse-free survival (LRFS), and disease-free survival (DFS). Significant differences were observed among the grade 0 and grade 2 CNN groups with regard to OS, RRFS, LRFS, DMFS, and DFS. Moreover, OS, LRFS, RRFS, and DFS were significantly different between the grade 1 and grade 2 CNN groups, whereas DMFS showed no significant differences. Univariate and multivariate analyses revealed CNN on MRI as a significant negative prognostic factor for OS, LRFS, RRFS, DMFS, and DFS in NPC patients. Conclusions: NPC patients with CNN of different grades show various prognosis and failure patterns after IMRT. CNN on MRI can be adopted as a predictive factor for formulating individualized treatment plans for NPC patients.

Absolute dose calculations for Monte Carlo simulations of radiotherapy beams.

PubMed

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

2005-07-21

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

Comparison of individual and composite field analysis using array detector for Intensity Modulated Radiotherapy dose verification.

PubMed

Saminathan, Sathiyan; Chandraraj, Varatharaj; Sridhar, C H; Manickam, Ravikumar

2012-01-01

To compare the measured and calculated individual and composite field planar dose distribution of Intensity Modulated Radiotherapy plans. The measurements were performed in Clinac DHX linear accelerator with 6 MV photons using Matrixx device and a solid water phantom. The 20 brain tumor patients were selected for this study. The IMRT plan was carried out for all the patients using Eclipse treatment planning system. The verification plan was produced for every original plan using CT scan of Matrixx embedded in the phantom. Every verification field was measured by the Matrixx. The TPS calculated and measured dose distributions were compared for individual and composite fields. The percentage of gamma pixel match for the dose distribution patterns were evaluated using gamma histogram. The gamma pixel match was 95-98% for 41 fields (39%) and 98% for 59 fields (61%) with individual fields. The percentage of gamma pixel match was 95-98% for 5 patients and 98% for other 12 patients with composite fields. Three patients showed a gamma pixel match of less than 95%. The comparison of percentage gamma pixel match for individual and composite fields showed more than 2.5% variation for 6 patients, more than 1% variation for 4 patients, while the remaining 10 patients showed less than 1% variation. The individual and composite field measurements showed good agreement with TPS calculated dose distribution for the studied patients. The measurement and data analysis for individual fields is a time consuming process, the composite field analysis may be sufficient enough for smaller field dose distribution analysis with array detectors.

S-1 chemotherapy and intensity-modulated radiotherapy after D1/D2 lymph node dissection in patients with node-positive gastric cancer: a phase I/II study.

PubMed

Wang, X; Zhao, D B; Yang, L; Chi, Y; Tang, Y; Li, N; Wang, S L; Song, Y W; Liu, Y P; Liu, W Y; Ren, H; Zhang, T; Wang, J Y; Chen, X S; Fang, H; Wang, W H; Li, Y X; Jin, J

2018-02-06

This phase I/II clinical trial investigated S-1 administered with intensity-modulated radiotherapy (IMRT) as adjuvant therapy for node-positive gastric cancer. Patients had undergone radical resection and D1/D2 lymph node dissection. In phase I, patients received adjuvant chemoradiotherapy of IMRT (45 Gy in 25 fractions) with concurrent S-1 administered on a dose-escalation schedule to determine the recommended dose (RD). In phase II, the safety and efficacy of the RD of S-1 combined with IMRT were assessed. We consecutively enrolled 73 patients (56 men; median age, 53 years; range, 29-73 years) and the phase I portion of the study included 27 patients. The RD of S-1 administered concomitantly with IMRT was 80 mg m -2  day -1 orally, twice daily. The phase II analysis included 52 patients (46 new patients plus 6 from phase I). 8 patients (15.4%) developed grade 3 or 4 toxicities. There were 21 recurrence events and 15 deaths (1 bowel obstruction, 14 gastric cancer). Three-year disease-free survival and overall survival were 62.2% (95% confidence interval (CI), 48.5-75.9) and 70.0% (95% CI, 56.3-83.7), respectively. The median time to recurrence was 17.5 months (range, 3.8-42.0). The median time from recurrence to death was 7.0 months (range, 1.5-28.7). S-1 combined with IMRT adjuvant chemoradiotherapy is safe and efficacious for advanced gastric cancer.

Changes Mimicking New Leptomeningeal Disease After Intensity-Modulated Radiotherapy for Medulloblastoma

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

Muscal, Jodi A.; Jones, Jeremy Y.; Paulino, Arnold C.

2009-01-01

Purpose: Acute and late changes in magnetic resonance imaging of the pediatric brain have been described after radiotherapy (RT). We report the post-RT neuroimaging changes in the posterior fossa after intensity-modulated RT (IMRT) in children with medulloblastoma and contrast them with those of leptomeningeal disease. Methods and Materials: We performed a retrospective review of 53 consecutive children with medulloblastoma who were treated with craniospinal RT followed by IMRT to the posterior fossa and chemotherapy between 1997 and 2006. Results: After IMRT to the posterior fossa, 8 (15%) of 53 patients developed increased fluid-attenuated inversion-recovery signal changes in the brainstem ormore » cerebellum and patchy, multifocal, nodular contrast enhancement at a median of 6 months. The enhancement superficially resembled leptomeningeal disease. However, the enhancement resolved without intervention at a median of 6 months later. The accompanying fluid-attenuated inversion-recovery signal changes occasionally preceded the enhancement, were often parenchymal in location, and resolved or persisted to a lesser degree. All 8 patients with transient magnetic resonance imaging changes in the posterior fossa were alive at last follow-up. In contrast, leptomeningeal disease occurred in 8 (15%) of our 53 patients at a median of 19.5 months after IMRT completion. Of these 8 patients, 7 demonstrated initial nodular enhancement outside the conformal field, and 7 patients died. Conclusion: Magnetic resonance imaging changes can occur in the posterior fossa of children treated with IMRT for medulloblastoma. In our experience, these transient changes occur at a characteristic time and location after RT, allowing them to be distinguished from leptomeningeal disease.« less

Prostate intensity-modulated radiotherapy planning in seven mouse clicks: Development of a class solution for cancer.

PubMed

Wood, Maree; Fonseca, Amara; Sampson, David; Kovendy, Andrew; Westhuyzen, Justin; Shakespeare, Thomas; Turnbull, Kirsty

2016-01-01

The aim of the retrospective study was to develop a planning class solution for prostate intensity-modulated radiotherapy (IMRT) that achieved target and organs-at-risk (OAR) doses within acceptable departmental protocol criteria using the Monaco treatment planning system (Elekta-CMS Software, MO, USA). Advances in radiation therapy technology have led to a re-evaluation of work practices. Class solutions have the potential to produce highly conformal plans in a time-efficient manner. Using data from intermediate and high risk prostate cancer patients, a stepwise quality improvement model was employed. Stage 1 involved the development of a broadly based treatment template developed across 10 patients. Stage 2 involved template refinement and clinical audit ( n  = 20); Stage 3, template review ( n  = 50) and Stage 4 an assessment of a revised template against the actual treatment plan involving 72 patients. The computer algorithm that comprised the Stage 4 template met clinical treatment criteria for 82% of patients. Minor template changes were required for a further 13% of patients. Major changes were required in 4%; one patient could not be assessed. The average calculation time was 13 min and involved seven mouse clicks by the planner. Thus, the new template met treatment criteria or required only minor changes in 95% of prostate patients; this is an encouraging result suggesting improvements in planning efficiency and consistency. It is feasible to develop a class solution for prostate IMRT using a stepwise quality improvement model which delivers clinically acceptable plans in the great majority of prostate cases.

Intensity-Modulated Radiotherapy in the Treatment of Oropharyngeal Cancer: An Update of the Memorial Sloan-Kettering Cancer Center Experience

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

Setton, Jeremy; Caria, Nicola; Romanyshyn, Jonathan

2012-01-01

Purpose: To update the Memorial Sloan-Kettering Cancer Center's experience with intensity-modulated radiotherapy (IMRT) in the treatment of oropharyngeal cancer (OPC). Methods and Materials: Between September 1998 and April 2009, 442 patients with histologically confirmed OPC underwent IMRT at our center. There were 379 men and 63 women with a median age of 57 years (range, 27-91). The disease was Stage I in 2%, Stage II in 4%, Stage III in 21%, and Stage IV in 73% of patients. The primary tumor subsite was tonsil in 50%, base of tongue in 46%, pharyngeal wall in 3%, and soft palate in 2%.more » The median prescription dose to the planning target volume of the gross tumor was 70 Gy for definitive (n = 412) cases and 66 Gy for postoperative cases (n = 30). A total 404 patients (91%) received chemotherapy, including 389 (88%) who received concurrent chemotherapy, the majority of which was platinum-based. Results: Median follow-up among surviving patients was 36.8 months (range, 3-135). The 3-year cumulative incidence of local failure, regional failure, and distant metastasis was 5.4%, 5.6%, and 12.5%, respectively. The 3-year OS rate was 84.9%. The incidence of late dysphagia and late xerostomia {>=}Grade 2 was 11% and 29%, respectively. Conclusions: Our results confirm the feasibility of IMRT in achieving excellent locoregional control and low rates of xerostomia. According to our knowledge, this study is the largest report of patients treated with IMRT for OPC.« less

SU-E-T-617: Plan Quality Estimation of Intensity-Modulated Radiotherapy Cases for Lung Cancer

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

Koo, J; Yoon, M; Chung, W

Purpose: To estimate the planning quality of intensity-modulated radiotherapy in lung cancer cases and to provide preliminary data for the development of a planning quality assurance algorithm. Methods: 42 IMRT plans previously used in cases of solitary lung cancers were collected. Organs in or near the thoracic cavity, such as lung (ipsilateral, contralateral), heart, liver, esophagus, cord and bronchus were considered as organs at risk (OARs) in this study. The coverage index (CVI), conformity index (CI), homogeneity index (HI), volume, irregularity (standard deviation of center-surface distance) were used to compare PTV dose characteristics. The effective uniform dose (EUD), V10Gy, andmore » V20Gy of the OARs were used to compare OAR dose characteristics. Results: Average CVI, CI, HI values were 0.9, 0.8, 0.1, respectively. CVI and CI had narrow Gaussian distribution curves without a singular value, but one case had a relatively high (0.25) HI because of location and irregular shape (Irregularity of 18.5 when average was 12.5) of PTV. EUDs tended to decrease as OAR-PTV distance increased and OAR-PTV overlap volume decreased. Conclusion: This work indicates the potential for significant plan quality deviation of similar lung cancer cases. Considering that this study were from a single department, differences in the treatment results for a given patient would be much more pronounced if multiple departments (and therefore more planners) were involved. Therefore, further examination of QA protocols is needed to reduce deviations in radiation treatment planning.« less

Inverse planning in three-dimensional conformal and intensity-modulated radiotherapy of mid-thoracic oesophageal cancer.

PubMed

Wu, V W C; Sham, J S T; Kwong, D L W

2004-07-01

The aim of this study is to demonstrate the use of inverse planning in three-dimensional conformal radiation therapy (3DCRT) of oesophageal cancer patients and to evaluate its dosimetric results by comparing them with forward planning of 3DCRT and inverse planning of intensity-modulated radiotherapy (IMRT). For each of the 15 oesophageal cancer patients in this study, the forward 3DCRT, inverse 3DCRT and inverse IMRT plans were produced using the FOCUS treatment planning system. The dosimetric results and the planner's time associated with each of the treatment plans were recorded for comparison. The inverse 3DCRT plans showed similar dosimetric results to the forward plans in the planning target volume (PTV) and organs at risk (OARs). However, they were inferior to that of the IMRT plans in terms of tumour control probability and target dose conformity. Furthermore, the inverse 3DCRT plans were less effective in reducing the percentage lung volume receiving a dose below 25 Gy when compared with the IMRT plans. The inverse 3DCRT plans delivered a similar heart dose as in the forward plans, but higher dose than the IMRT plans. The inverse 3DCRT plans significantly reduced the operator's time by 2.5 fold relative to the forward plans. In conclusion, inverse planning for 3DCRT is a reasonable alternative to the forward planning for oesophageal cancer patients with reduction of the operator's time. However, IMRT has the better potential to allow further dose escalation and improvement of tumour control.

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

PubMed

Yang, Zhaozhi; Zhang, Li; Chen, Xingxing; Ma, Jinli; Mei, Xin; Chen, Jiayi; Yu, Xiaoli; Guo, Xiaomao

2015-10-27

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

Optimal gross tumor volume definition in lung-sparing intensity modulated radiotherapy for pleural mesothelioma: an in silico study.

PubMed

Botticella, Angela; Defraene, Gilles; Nackaerts, Kristiaan; Deroose, Christophe M; Coolen, Johan; Nafteux, Philippe; Peeters, Stephanie; Ricardi, Umberto; De Ruysscher, Dirk

2016-12-01

The gross tumor volume (GTV) definition for malignant pleural mesothelioma (MPM) is ill-defined. We therefore investigated which imaging modality is optimal: computed tomography (CT) with intravenous contrast (IVC), positron emission tomography-CT (PET/CT) or magnetic resonance imaging (MRI). Sixteen consecutive patients with untreated stage I-IV MPM were included. Patients with prior pleurodesis were excluded. CT with IVC, 18FDG-PET/CT and MRI (T2 and contrast-enhanced T1) were obtained. CT was rigidly co-registered with PET/CT and with MRI. Three sets of pleural GTVs were defined: GTV CT , GTV CT+PET/CT and GTV CT+MRI . Quantitative and qualitative evaluations of the contoured GTVs were performed. Compared to CT-based GTV definition, PET/CT identified additional tumor sites (defined as either separate nodules or greater extent of a known tumor) in 12/16 patients. Compared to either CT or PET/CT, MRI identified additional tumor sites in 15/16 patients (p = .7). The mean GTV CT , GTV CT+PET/CT and GTV CT+MRI [±standard deviation (SD)] were 630.1 cm 3 (±302.81), 640.23 cm 3 (±302.83) and 660.8 cm 3 (±290.8), respectively. Differences in mean volumes were not significant. The mean Jaccard Index was significantly lower in MRI-based contours versus all the others. As MRI identified additional pleural disease sites in the majority of patients, it may play a role in optimal target volume definition.

Patient specific quality control for Stereotactic Ablative Body Radiotherapy (SABR): it takes more than one phantom

NASA Astrophysics Data System (ADS)

Kron, T.; Ungureanu, E.; Antony, R.; Hardcastle, N.; Clements, N.; Ukath, J.; Fox, C.; Lonski, P.; Wanigaratne, D.; Haworth, A.

2017-01-01

Stereotactic Ablative Body Radiotherapy (SABR) is an extension of the concepts of Stereotactic Radiosurgery from intracranial procedures to extracranial targets. This brings with it new technological challenges for set-up of a SABR program and continuing quality assurance. Compared with intracranial procedures SABR requires consideration of motion and inhomogeneities and has to deal with a much larger variety of targets ranging from lung to liver, kidney and bone. To meet many of the challenges virtually all advances in modern radiotherapy, such as Intensity Modulated and Image Guided Radiation Therapy (IMRT and IGRT) are used. Considering the few fractions and high doses per fraction delivered to complex targets it is not surprising that patient specific quality control is considered essential for safe delivery. Given the variety of targets and clinical scenarios we employ different strategies for different patients to ensure that the most important aspects of the treatment are appropriately tested, be it steep dose gradients, inhomogeneities or the delivery of dose in the presence of motion. The current paper reviews the different approaches and phantoms utilised at Peter MacCallum Cancer Centre for SABR QA.

A fast optimization algorithm for multicriteria intensity modulated proton therapy planning.

PubMed

Chen, Wei; Craft, David; Madden, Thomas M; Zhang, Kewu; Kooy, Hanne M; Herman, Gabor T

2010-09-01

To describe a fast projection algorithm for optimizing intensity modulated proton therapy (IMPT) plans and to describe and demonstrate the use of this algorithm in multicriteria IMPT planning. The authors develop a projection-based solver for a class of convex optimization problems and apply it to IMPT treatment planning. The speed of the solver permits its use in multicriteria optimization, where several optimizations are performed which span the space of possible treatment plans. The authors describe a plan database generation procedure which is customized to the requirements of the solver. The optimality precision of the solver can be specified by the user. The authors apply the algorithm to three clinical cases: A pancreas case, an esophagus case, and a tumor along the rib cage case. Detailed analysis of the pancreas case shows that the algorithm is orders of magnitude faster than industry-standard general purpose algorithms (MOSEK'S interior point optimizer, primal simplex optimizer, and dual simplex optimizer). Additionally, the projection solver has almost no memory overhead. The speed and guaranteed accuracy of the algorithm make it suitable for use in multicriteria treatment planning, which requires the computation of several diverse treatment plans. Additionally, given the low memory overhead of the algorithm, the method can be extended to include multiple geometric instances and proton range possibilities, for robust optimization.

Comparison of treatment plans: a retrospective study by the method of radiobiological evaluation

NASA Astrophysics Data System (ADS)

Puzhakkal, Niyas; Kallikuzhiyil Kochunny, Abdullah; Manthala Padannayil, Noufal; Singh, Navin; Elavan Chalil, Jumanath; Kulangarakath Umer, Jamshad

2016-09-01

There are many situations in radiotherapy where multiple treatment plans need to be compared for selection of an optimal plan. In this study we performed the radiobiological method of plan evaluation to verify the treatment plan comparison procedure of our clinical practice. We estimated and correlated various radiobiological dose indices with physical dose metrics for a total of 30 patients representing typical cases of head and neck, prostate and brain tumors. Three sets of plans along with a clinically approved plan (final plan) treated by either Intensity Modulated Radiation Therapy (IMRT) or Rapid Arc (RA) techniques were considered. The study yielded improved target coverage for final plans, however, no appreciable differences in doses and the complication probabilities of organs at risk were noticed. Even though all four plans showed adequate dose distributions, from dosimetric point of view, the final plan had more acceptable dose distribution. The estimated biological outcome and dose volume histogram data showed least differences between plans for IMRT when compared to RA. Our retrospective study based on 120 plans, validated the radiobiological method of plan evaluation. The tumor cure or normal tissue complication probabilities were found to be correlated with the corresponding physical dose indices.

Clinical outcomes using carbon-ion radiotherapy and dose-volume histogram comparison between carbon-ion radiotherapy and photon therapy for T2b-4N0M0 non-small cell lung cancer-A pilot study.

PubMed

Shirai, Katsuyuki; Kawashima, Motohiro; Saitoh, Jun-Ichi; Abe, Takanori; Fukata, Kyohei; Shigeta, Yuka; Irie, Daisuke; Shiba, Shintaro; Okano, Naoko; Ohno, Tatsuya; Nakano, Takashi

2017-01-01

The safety and efficacy of carbon-ion radiotherapy for advanced non-small cell lung cancer have not been established. We evaluated the clinical outcomes and dose-volume histogram parameters of carbon-ion radiotherapy compared with photon therapy in T2b-4N0M0 non-small cell lung cancer. Twenty-three patients were treated with carbon-ion radiotherapy between May 2011 and December 2015. Seven, 14, and 2 patients had T2b, T3, and T4, respectively. The median age was 78 (range, 53-91) years, with 22 male patients. There were 12 adenocarcinomas, 8 squamous cell carcinomas, 1 non-small cell lung carcinoma, and 2 clinically diagnosed lung cancers. Eleven patients were operable, and 12 patients were inoperable. Most patients (91%) were treated with carbon-ion radiotherapy of 60.0 Gy relative biological effectiveness (RBE) in 4 fractions or 64.0 Gy (RBE) in 16 fractions. Local control and overall survival rates were calculated. Dose-volume histogram parameters of normal lung and tumor coverages were compared between carbon-ion radiotherapy and photon therapies, including three-dimensional conformal radiotherapy (3DCRT) and intensity-modulated radiotherapy (IMRT). The median follow-up of surviving patients was 25 months. Three patients experienced local recurrence, and the 2-year local control rate was 81%. During follow-up, 5 patients died of lung cancer, and 1 died of intercurrent disease. The 2-year overall survival rate was 70%. Operable patients had a better overall survival rate compared with inoperable patients (100% vs. 43%; P = 0.04). There was no grade ≥2 radiation pneumonitis. In dose-volume histogram analysis, carbon-ion radiotherapy had a significantly lower dose to normal lung and greater tumor coverage compared with photon therapies. Carbon-ion radiotherapy was effectively and safely performed for T2b-4N0M0 non-small cell lung cancer, and the dose distribution was superior compared with those for photon therapies. A Japanese multi-institutional study is ongoing to prospectively evaluate these patients and establish the use of carbon-ion radiotherapy.

Multiband phase-modulated radio over IsOWC link with balanced coherent homodyne detection

NASA Astrophysics Data System (ADS)

Zong, Kang; Zhu, Jiang

2017-11-01

In this paper, we present a multiband phase-modulated radio over intersatellite optical wireless communication (IsOWC) link with balanced coherent homodyne detection. The proposed system can provide high linearity for transparent transport of multiband radio frequency (RF) signals and better receiver sensitivity than intensity modulated with direct detection (IM/DD) system. The exact analytical expression of signal to noise and distortion ratio (SNDR) is derived considering the third-order intermodulation product and amplifier spontaneous emission (ASE) noise. Numerical results of SNDR with various number of subchannels and modulation index are given. Results indicate that the optimal modulation index exists to maximize the SNDR. With the same system parameters, the value of the optimal modulation index will decrease with the increase of number of subchannels.

Haematological toxicity: a marker of adjuvant chemotherapy efficacy in stage II and III breast cancer.

PubMed Central

Saarto, T.; Blomqvist, C.; Rissanen, P.; Auvinen, A.; Elomaa, I.

1997-01-01

Two hundred and eleven patients with node-positive stage II and III breast cancer were treated with eight cycles of adjuvant chemotherapy comprising cyclophosphamide, doxorubicin and oral ftorafur (CAFt), with and without tamoxifen. All patients had undergone radical surgery, and 148 patients were treated with post-operative radiotherapy in two randomized studies. The impact of haematological toxicity of CAFt on distant disease-free (DDFS) and overall survival (OS) was recorded. Dose intensity of all given cycles (DI), dose intensity of the two initial cycles (DI2) and total dose (TD) were calculated separately for all chemotherapy drugs and were correlated with DDFS and OS. Patients with a lower leucocyte nadir during the chemotherapy had significantly better DDFS and OS (P = 0.01 and 0.04 respectively). Dose intensity of the two first cycles also correlated significantly with DDFS (P = 0.05) in univariate but not in multivariate analysis, while the leucocyte nadir retained its prognostic value. These results indicate that the leucocyte nadir during the adjuvant chemotherapy is a biological marker of chemotherapy efficacy; this presents the possibility of establishing an optimal dose intensity for each patient. The initial dose intensity of adjuvant chemotherapy also seems to be important in assuring the optimal effect of adjuvant chemotherapy. PMID:9010042

Using individual patient anatomy to predict protocol compliance for prostate intensity-modulated radiotherapy

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

Caine, Hannah; Whalley, Deborah; Kneebone, Andrew

If a prostate intensity-modulated radiation therapy (IMRT) or volumetric-modulated arc therapy (VMAT) plan has protocol violations, it is often a challenge knowing whether this is due to unfavorable anatomy or suboptimal planning. This study aimed to create a model to predict protocol violations based on patient anatomical variables and their potential relationship to target and organ at risk (OAR) end points in the setting of definitive, dose-escalated IMRT/VMAT prostate planning. Radiotherapy plans from 200 consecutive patients treated with definitive radiation for prostate cancer using IMRT or VMAT were analyzed. The first 100 patient plans (hypothesis-generating cohort) were examined to identifymore » anatomical variables that predict for dosimetric outcome, in particular OAR end points. Variables that scored significance were further assessed for their ability to predict protocol violations using a Classification and Regression Tree (CART) analysis. These results were then validated in a second group of 100 patients (validation cohort). In the initial analysis of the hypothesis-generating cohort, percentage of rectum overlap in the planning target volume (PTV) (%OR) and percentage of bladder overlap in the PTV (%OB) were highlighted as significant predictors of rectal and bladder dosimetry. Lymph node treatment was also significant for bladder outcomes. For the validation cohort, CART analysis showed that %OR of < 6%, 6% to 9% and > 9% predicted a 13%, 63%, and 100% rate of rectal protocol violations respectively. For the bladder, %OB of < 9% vs > 9% is associated with 13% vs 88% rate of bladder constraint violations when lymph nodes were not treated. If nodal irradiation was delivered, plans with a %OB of < 9% had a 59% risk of violations. Percentage of rectum and bladder within the PTV can be used to identify individual plan potential to achieve dose-volume histogram (DVH) constraints. A model based on these factors could be used to reduce planning time, improve work flow, and strengthen plan quality and consistency.« less

Feasibility study of volumetric modulated arc therapy with constant dose rate for endometrial cancer

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

Yang, Ruijie; Wang, Junjie, E-mail: junjiewang47@yahoo.com; Xu, Feng

2013-10-01

To investigate the feasibility, efficiency, and delivery accuracy of volumetric modulated arc therapy with constant dose rate (VMAT-CDR) for whole-pelvic radiotherapy (WPRT) of endometrial cancer. The nine-field intensity-modulated radiotherapy (IMRT), VMAT with variable dose-rate (VMAT-VDR), and VMAT-CDR plans were created for 9 patients with endometrial cancer undergoing WPRT. The dose distribution of planning target volume (PTV), organs at risk (OARs), and normal tissue (NT) were compared. The monitor units (MUs) and treatment delivery time were also evaluated. For each VMAT-CDR plan, a dry run was performed to assess the dosimetric accuracy with MatriXX from IBA. Compared with IMRT, the VMAT-CDRmore » plans delivered a slightly greater V{sub 20} of the bowel, bladder, pelvis bone, and NT, but significantly decreased the dose to the high-dose region of the rectum and pelvis bone. The MUs decreased from 1105 with IMRT to 628 with VMAT-CDR. The delivery time also decreased from 9.5 to 3.2 minutes. The average gamma pass rate was 95.6% at the 3%/3 mm criteria with MatriXX pretreatment verification for 9 patients. VMAT-CDR can achieve comparable plan quality with significant shorter delivery time and smaller number of MUs compared with IMRT for patients with endometrial cancer undergoing WPRT. It can be accurately delivered and be an alternative to IMRT on the linear accelerator without VDR capability.« less

Setup in a clinical workflow and impact on radiotherapy routine of an in vivo dosimetry procedure with an electronic portal imaging device

PubMed Central

Piermattei, Angelo; Kang, Shengwei; Xiao, Mingyong; Tang, Bin; Liao, Xiongfei; Xin, Xin; Grusio, Mattia

2018-01-01

High conformal techniques such as intensity-modulated radiation therapy and volumetric-modulated arc therapy are widely used in overloaded radiotherapy departments. In vivo dosimetric screening is essential in this environment to avoid important dosimetric errors. This work examines the feasibility of introducing in vivo dosimetry (IVD) checks in a radiotherapy routine. The causes of dosimetric disagreements between delivered and planned treatments were identified and corrected during the course of treatment. The efficiency of the corrections performed and the added workload needed for the entire procedure were evaluated. The IVD procedure was based on an electronic portal imaging device. A total of 3682 IVD tests were performed for 147 patients who underwent head and neck, abdomen, pelvis, breast, and thorax radiotherapy treatments. Two types of indices were evaluated and used to determine if the IVD tests were within tolerance levels: the ratio R between the reconstructed and planned isocentre doses and a transit dosimetry based on the γ-analysis of the electronic portal images. The causes of test outside tolerance level were investigated and corrected and IVD test was repeated during subsequent fraction. The time needed for each step of the IVD procedure was registered. Pelvis, abdomen, and head and neck treatments had 10% of tests out of tolerance whereas breast and thorax treatments accounted for up to 25%. The patient setup was the main cause of 90% of the IVD tests out of tolerance and the remaining 10% was due to patient morphological changes. An average time of 42 min per day was sufficient to monitor a daily workload of 60 patients in treatment. This work shows that IVD performed with an electronic portal imaging device is feasible in an overloaded department and enables the timely realignment of the treatment quality indices in order to achieve a patient’s final treatment compliant with the one prescribed. PMID:29432473

Applying the technique of volume-modulated arc radiotherapy to upper esophageal carcinoma.

PubMed

Ma, Pan; Wang, Xiaozhen; Xu, Yingjie; Dai, Jianrong; Wang, Luhua

2014-05-08

This study aims to evaluate the possibility of using the technique of volume-modulated arc therapy (VMAT) to combine the advantages of simplified intensity-modulated radiation therapy (sIMRT) with that of regular intensity-modulated radiation therapy (IMRT) in upper esophageal cancer. Ten patients with upper esophageal carcinoma were randomly chosen in this retrospective study. sIMRT, IMRT, and VMAT plans were generated to deliver 60 Gy in 30 fractions to the planning target volume (PTV). For each patient, with the same clinical requirements (target dose prescription, and dose/dose-volume constraints to organs at risk (OARs)), three plans were designed for sIMRT (five equispaced coplanar beams), IMRT (seven equispaced coplanar beams), and VMAT (two complete arcs). Comparisons were performed for dosimetric parameters of PTV and of OARs (lungs, spinal cord PRV, heart and normal tissue (NT)). All the plans were delivered to a phantom to evaluate the treatment time. The Wilcoxon matched-pairs, signed-rank test was used for intragroup comparison. For all patients, compared to sIMRT plans, VMAT plans statistically provide: a) significant improvement in HI and CI for PTV; b) significant decrease in delivery time, lung V20, MLD, heart V30 and spinal cord PRV D1cc; c) significant increase in NT V5; and d) no significant reduction in lung V5, V10, and heart MD. For all patients, compared to IMRT plans, VMAT plans statistically provide: a) significant improvement in CI for PTV; b) significant decrease in delivery time, lung V20, MLD, NT and spinal cord PRV D1cc; c) significant increase in NT V5; and d) no significant reduction in HI for PTV, lung V5, V10, heart V30 and heart MD. For patients with upper esophageal carcinoma, using VMAT significantly reduces the delivery time and the dose to the lungs compared with IMRT, and consequently saves as much treatment time as sIMRT. Considering those significant advantages, compared to sIMRT and IMRT, VMAT is the first choice of radiotherapy techniques for upper esophageal carcinoma.

Applicator-guided volumetric-modulated arc therapy for low-risk endometrial cancer

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

Cilla, Savino, E-mail: savinocilla@gmail.com; Macchia, Gabriella; Sabatino, Domenico

2013-04-01

The aim of this study was to report the feasibility of volumetric-modulated arc therapy (VMAT) in the postoperative irradiation of the vaginal vault. Moreover, the VMAT technique was compared with 3D conformal radiotherapy (3D-CRT) and fixed-field intensity-modulated radiotherapy (IMRT), in terms of target coverage and organs at risk sparing. The number of monitor units and the delivery time were analyzed to score the treatment efficiency. All plans were verified in a dedicated solid water phantom using a 2D array of ionization chambers. Twelve patients with endometrial carcinoma who underwent radical hystero-adenexectomy and fixed-field IMRT treatments were retrospectively included in thismore » analysis; for each patient, plans were compared in terms of dose-volume histograms, homogeneity index, and conformity indexes. All techniques met the prescription goal for planning target volume coverage, with VMAT showing the highest level of conformity at all dose levels. VMAT resulted in significant reduction of rectal and bladder volumes irradiated at all dose levels compared with 3D-CRT. No significant differences were found with respect to IMRT. Moreover, a significant improvement of the dose conformity was reached by VMAT technique not only at the 95% dose level (0.74 vs. 0.67 and 0.62) but also at 50% and 75% levels of dose prescription. In addition, VMAT plans showed a significant reduction of monitor units by nearly 28% with respect to IMRT, and reduced treatment time from 11 to <3 minutes for a single 6-Gy fraction. In conclusion, VMAT plans can be planned and carried out with high quality and efficiency for the irradiation of vaginal vault alone, providing similar or better sparing of organs at risk to fixed-field IMRT and resulting in the most efficient treatment option. VMAT is currently our standard approach for radiotherapy of low-risk endometrial cancer.« less

Grid therapy using high definition multileaf collimators: realizing benefits of the bystander effect.

PubMed

Peng, Valery; Suchowerska, Natalka; Rogers, Linda; Claridge Mackonis, Elizabeth; Oakes, Samantha; McKenzie, David R

2017-08-01

In microbeam radiotherapy (MRT), parallel arrays of high-intensity synchrotron x-ray beams achieve normal tissue sparing without compromising tumor control. Grid-therapy using clinical linacs has spatial modulation on a larger scale and achieves promising results for palliative treatments of bulky tumors. The availability of high definition multileaf collimators (HDMLCs) with 2.5 mm leaves provides an opportunity for grid-therapy to more closely approach MRT. However, challenges to the wider implementation of grid-therapy remain because spatial modulation of the target volume runs counter to current radiotherapy practice and mechanisms for the beneficial effects of MRT are not fully understood. Without more knowledge of cell dose responses, a quantitative basis for planning treatments is difficult. The aim of this study is to determine if therapeutic benefits of MRT can be achieved using a linac with HDMLCs and if so, to develop a predictive model to support treatment planning. HD120-MLCs of a Varian Novalis TX TM were used to generate grid patterns of 2.5 and 5.0 mm spacing, which were characterized dosimetrically using Gafchromic TM EBT3 film. Clonogenic survival of normal (HUVEC) and cancer (NCI-H460, HCC-1954) cell lines following irradiation under the grid and open fields using a 6 MV photon beam were compared in-vitro for the same average dose. Relative to an open field, survival of normal cells in a 2.5 mm striped field was the same, while the survival of both cancer cell lines was significantly lower. A mathematical model was developed to incorporate dose gradients of the spatial modulation into the standard linear quadratic model. Our new bystander extended LQ model assumes spatial gradients drive the diffusion of soluble factors that influence survival through bystander effects, successfully predicting the experimental results that show an increased therapeutic ratio. Our results challenge conventional radiotherapy practice and propose that additional gain can be realized by prescribing spatially modulated treatments to harness the bystander effect.

WE-F-BRB-01: The Power of Ontologies and Standardized Terminologies for Capturing Clinical Knowledge

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

Gabriel, P.

2015-06-15

Advancements in informatics in radiotherapy are opening up opportunities to improve our ability to assess treatment plans. Models on individualizing patient dose constraints from prior patient data and shape relationships have been extensively researched and are now making their way into commercial products. New developments in knowledge based treatment planning involve understanding the impact of the radiation dosimetry on the patient. Akin to radiobiology models that have driven intensity modulated radiotherapy optimization, toxicity and outcome predictions based on treatment plans and prior patient experiences may be the next step in knowledge based planning. In order to realize these predictions, itmore » is necessary to understand how the clinical information can be captured, structured and organized with ontologies and databases designed for recall. Large databases containing radiation dosimetry and outcomes present the opportunity to evaluate treatment plans against predictions of toxicity and disease response. Such evaluations can be based on dose volume histogram or even the full 3-dimensional dose distribution and its relation to the critical anatomy. This session will provide an understanding of ontologies and standard terminologies used to capture clinical knowledge into structured databases; How data can be organized and accessed to utilize the knowledge in planning; and examples of research and clinical efforts to incorporate that clinical knowledge into planning for improved care for our patients. Learning Objectives: Understand the role of standard terminologies, ontologies and data organization in oncology Understand methods to capture clinical toxicity and outcomes in a clinical setting Understand opportunities to learn from clinical data and its application to treatment planning Todd McNutt receives funding from Philips, Elekta and Toshiba for some of the work presented.« less

WE-F-BRB-00: New Developments in Knowledge-Based Treatment Planning and Automation

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

NONE

2015-06-15

Advancements in informatics in radiotherapy are opening up opportunities to improve our ability to assess treatment plans. Models on individualizing patient dose constraints from prior patient data and shape relationships have been extensively researched and are now making their way into commercial products. New developments in knowledge based treatment planning involve understanding the impact of the radiation dosimetry on the patient. Akin to radiobiology models that have driven intensity modulated radiotherapy optimization, toxicity and outcome predictions based on treatment plans and prior patient experiences may be the next step in knowledge based planning. In order to realize these predictions, itmore » is necessary to understand how the clinical information can be captured, structured and organized with ontologies and databases designed for recall. Large databases containing radiation dosimetry and outcomes present the opportunity to evaluate treatment plans against predictions of toxicity and disease response. Such evaluations can be based on dose volume histogram or even the full 3-dimensional dose distribution and its relation to the critical anatomy. This session will provide an understanding of ontologies and standard terminologies used to capture clinical knowledge into structured databases; How data can be organized and accessed to utilize the knowledge in planning; and examples of research and clinical efforts to incorporate that clinical knowledge into planning for improved care for our patients. Learning Objectives: Understand the role of standard terminologies, ontologies and data organization in oncology Understand methods to capture clinical toxicity and outcomes in a clinical setting Understand opportunities to learn from clinical data and its application to treatment planning Todd McNutt receives funding from Philips, Elekta and Toshiba for some of the work presented.« less

WE-F-BRB-02: Setting the Stage for Incorporation of Toxicity Measures in Treatment Plan Assessments

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

Mayo, C.

2015-06-15

Advancements in informatics in radiotherapy are opening up opportunities to improve our ability to assess treatment plans. Models on individualizing patient dose constraints from prior patient data and shape relationships have been extensively researched and are now making their way into commercial products. New developments in knowledge based treatment planning involve understanding the impact of the radiation dosimetry on the patient. Akin to radiobiology models that have driven intensity modulated radiotherapy optimization, toxicity and outcome predictions based on treatment plans and prior patient experiences may be the next step in knowledge based planning. In order to realize these predictions, itmore » is necessary to understand how the clinical information can be captured, structured and organized with ontologies and databases designed for recall. Large databases containing radiation dosimetry and outcomes present the opportunity to evaluate treatment plans against predictions of toxicity and disease response. Such evaluations can be based on dose volume histogram or even the full 3-dimensional dose distribution and its relation to the critical anatomy. This session will provide an understanding of ontologies and standard terminologies used to capture clinical knowledge into structured databases; How data can be organized and accessed to utilize the knowledge in planning; and examples of research and clinical efforts to incorporate that clinical knowledge into planning for improved care for our patients. Learning Objectives: Understand the role of standard terminologies, ontologies and data organization in oncology Understand methods to capture clinical toxicity and outcomes in a clinical setting Understand opportunities to learn from clinical data and its application to treatment planning Todd McNutt receives funding from Philips, Elekta and Toshiba for some of the work presented.« less

WE-F-BRB-03: Inclusion of Data-Driven Risk Predictions in Radiation Treatment Planning in the Context of a Local Level Learning Health System

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

McNutt, T.

Advancements in informatics in radiotherapy are opening up opportunities to improve our ability to assess treatment plans. Models on individualizing patient dose constraints from prior patient data and shape relationships have been extensively researched and are now making their way into commercial products. New developments in knowledge based treatment planning involve understanding the impact of the radiation dosimetry on the patient. Akin to radiobiology models that have driven intensity modulated radiotherapy optimization, toxicity and outcome predictions based on treatment plans and prior patient experiences may be the next step in knowledge based planning. In order to realize these predictions, itmore » is necessary to understand how the clinical information can be captured, structured and organized with ontologies and databases designed for recall. Large databases containing radiation dosimetry and outcomes present the opportunity to evaluate treatment plans against predictions of toxicity and disease response. Such evaluations can be based on dose volume histogram or even the full 3-dimensional dose distribution and its relation to the critical anatomy. This session will provide an understanding of ontologies and standard terminologies used to capture clinical knowledge into structured databases; How data can be organized and accessed to utilize the knowledge in planning; and examples of research and clinical efforts to incorporate that clinical knowledge into planning for improved care for our patients. Learning Objectives: Understand the role of standard terminologies, ontologies and data organization in oncology Understand methods to capture clinical toxicity and outcomes in a clinical setting Understand opportunities to learn from clinical data and its application to treatment planning Todd McNutt receives funding from Philips, Elekta and Toshiba for some of the work presented.« less

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

Chang Jenghwa; Kowalski, Alex; Hou, Bob

The purpose of this work was to study the feasibility of incorporating functional magnetic resonance imaging (fMRI) information for intensity modulated radiotherapy (IMRT) treatment planning of brain tumors. Three glioma patients were retrospectively replanned for radiotherapy (RT) with additional fMRI information. The fMRI of each patient was acquired using a bilateral finger-tapping paradigm with a gradient echo EPI (Echo Planer Imaging) sequence. The fMRI data were processed using the Analysis of Functional Neuroimaging (AFNI) software package for determining activation volumes, and the volumes were fused with the simulation computed tomography (CT) scan. The actived pixels in left and right primarymore » motor cortexes (PMCs) were contoured as critical structures for IMRT planning. The goal of replanning was to minimize the RT dose to the activation volumes in the PMC regions, while maintaining a similar coverage to the planning target volume (PTV) and keeping critical structures within accepted dose tolerance. Dose-volume histograms of the treatment plans with and without considering the fMRI information were compared. Beam angles adjustment or additional beams were needed for 2 cases to meet the planning criteria. Mean dose to the contralateral and ipsilateral PMC was significantly reduced by 66% and 55%, respectively, for 1 patient. For the other 2 patients, mean dose to contralateral PMC region was lowered by 73% and 69%. In general, IMRT optimization can reduce the RT dose to the PMC regions without compromising the PTV coverage or sparing of other critical organs. In conclusion, it is feasible to incorporate the fMRI information into the RT treatment planning. IMRT planning allows a significant reduction in RT dose to the PMC regions, especially if the region does not lie within the PTV.« less

Intentional avoidance of the esophagus using intensity modulated radiation therapy to reduce dysphagia after palliative thoracic radiation.

PubMed

Granton, Patrick V; Palma, David A; Louie, Alexander V

2017-01-26

Palliative thoracic radiotherapy is an effective technique to alleviate symptoms of disease burden in advanced-stage lung cancer patients. Previous randomized controlled studies demonstrated a survival benefit in patients with good performance status at radiation doses of 35Gy 10 or greater but with an increased incidence of esophagitis. The objective of this planning study was to assess the potential impact of esophageal-sparing IMRT (ES-IMRT) compared to the current standard of care using parallel-opposed pair beams (POP). In this study, 15 patients with lung cancer treated to a dose of 30Gy in 10 fractions between August 2015 and January 2016 were identified. Radiation treatment plans were optimized using ES-IMRT by limiting the max esophagus point dose to 24Gy. Using published Lyman-Kutcher-Burman normal tissue complication probabilities (LKB-NTCP) models, both plans were evaluated for the likelihood of esophagitis (≥ grade 2) and pneumonitis (≥ grade 2). Using ES-IMRT, the median esophageal and lung mean doses reduced from 16 and 8Gy to 7 and 7Gy, respectively. Using the LKB models, the theoretical probability of symptomatic esophagitis and pneumonitis reduced from 13 to 2%, and from 5 to 3%, respectively. The median normalize total dose (NTD mean) accounting for fraction size for the GTV and PTV of the clinically approved POP plans compared to the ES-IMRT plans were similar. Advanced radiotherapy techniques such as ES-IMRT may have clinical utility in reducing treatment-related toxicity in advanced lung cancer patients. Our data suggests that the rate of esophagitis can be reduced without compromising local control.

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

PubMed Central

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

2014-01-01

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

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

PubMed

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

2014-04-01

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

Patterns of care analysis for head & neck cancer of unknown primary site: a survey inside the German society of radiation oncology (DEGRO).

PubMed

Müller von der Grün, Jens; Bon, Dimitra; Rödel, Claus; Balermpas, Panagiotis

2018-05-14

Due to the absence of randomized trials, the optimal management for squamous cell cancer of unknown primary in the head and neck region (SCCHN CUP) remains controversial. Current strategies are based on retrospective studies, clinical experience, and institutional policies. An anonymous questionnaire with a total of 24 questions was created and distributed by the use of an online version (Google Forms®, Google, Mountain View, CA, USA) as well as a printout version as equivalent option. An email with a link to the survey and the questionnaire as attachment was sent to 361 DEGRO(German Society of Radiation Oncology)-associated departments. Frequency distributions of responses for each question were calculated. The data were also analyzed by type of practice. Representativity of the sample size for the DEGRO was also evaluated. 66 responses were received including answers from 20 (30%) university departments, 16 (24%) non-university institutions, and 30 (46%) radiation oncology practices. 95% of the participants routinely present these cases in an interdisciplinary tumor board and use intensity modulated radiotherapy (IMRT) techniques for SCCHN CUP treatment. Surgery includes neck dissection in 83% and tonsillectomy in 73% of the cases. Human papilloma virus (HPV) status is routinely determined in 82% of the departments. Statistically significant differences between universities and institutions and clinics and practices could be found with respect to positron emission tomography-computed tomography (PET-CT) utilization, indications for chemotherapy, radiotherapy volumes, and cumulative doses. Diagnostics and treatment for SCCHN CUP within the DEGRO remain heterogeneous. A prospective register trial with standard operation procedures is warranted to homogenize and possibly improve management.

Robotic radiosurgery vs. brachytherapy as a boost to intensity modulated radiotherapy for tonsillar fossa and soft palate tumors: the clinical and economic impact of an emerging technology.

PubMed

Nijdam, W; Levendag, P; Fuller, D; Schulz, R; Prevost, J-B; Noever, I; Uyl-de Groot, C

2007-12-01

As a basis for making decisions regarding optimal treatment for patients with tonsillar fossa and soft palate tumors, we conducted a preliminary investigation of costs and quality of life (QoL) for two modalities [brachytherapy (BT) and robotic radiosurgery] used to boost radiation to the primary tumors following external beam radiotherapy. BT was well established in our center; a boost by robotic radiosurgery was begun more recently in patients for whom BT was not technically feasible. Robotic radiosurgery boost treatment has the advantage of being non-invasive and is able to reach tumors in cases where there is deep parapharyngeal tumor extension. A neck dissection was performed for patients with nodal-positive disease. Quality of life (pain and difficulty swallowing) was established in long-term follow-up for patients undergoing BT and over a one-year follow-up in robotic radiosurgery patients. Total hospital costs for both groups were computed. Our results show that efficacy and quality of life at one year are comparable for BT and robotic radiosurgery. Total cost for robotic radiosurgery was found to be less than BT primarily due to the elimination of hospital admission and operating room expenses. Confirmation of robotic radiosurgery treatment efficacy and reduced morbidity in the long term requires further study. Quality of life and cost analyses are critical to Health Technology Assessments (HTA). The present study shows how a preliminary HTA of a new medical technology such as robotic radiosurgery with its typical hypofractionation characteristics might be based on short-term clinical outcomes and assumptions of equivalence.

Hypofractionated radiation therapy for prostate cancer: The McGill University Health Center experience.

PubMed

Barbosa Neto, O; Souhami, L; Faria, S

2015-10-01

In 2002, at the McGill University Health Centre, we began a program of hypofractionated radiotherapy for patients with low risk prostate cancer as an alternative to conventionally fractionated radiotherapy. Our initial hypofractionation regimen was 66 Gy given in 22 fractions, prescribed to the isocenter, delivered with 3D-conformal radiotherapy plan. The clinical target volume was the prostate gland and the planning target volume consisted of the clinical target volume plus a 7-mm margin in all directions. Hormonal therapy was not given to any patient. The long-term results for this group of patients confirmed the feasibility, good tolerance and excellent disease control of the regimen with the extra-benefit of being convenient to both patients and the health system by shortening treatment duration. The outcomes of this approach stimulated us to use hypofractionation in patients with intermediate-risk. Analysis of 100 intermediate-risk patients receiving our hypofractionated radiotherapy regimen (no hormones) shows, at median follow-up of 75 months, 8-year biochemical recurrence free and cancer specific survival rates of 90% and 95%, respectively, with acceptable toxicity. Our technique changed from 3D to intensity modulated radiotherapy with the dose adjusted to 60 Gy in 20 fractions. Lastly, we have expanded the program to high-risk patients where IMRT treatments are given to the pelvic nodes (44 Gy in 20 fractions) with a simultaneous integrated boost delivery to the prostate (60 Gy in the same 20 fractions). Our long-term results have shown that moderate hypofractionated radiotherapy for prostate cancer is safe and provides good tumor control comparable to high-dose conventionally fractionated radiotherapy. This hypofractionated regimen has been routinely used in our institution. Copyright © 2015 Société française de radiothérapie oncologique (SFRO). Published by Elsevier SAS. All rights reserved.

A case study of radiotherapy planning for Intensity Modulation Radiation Therapy for the whole scalp with matching electron treatment

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

Sponseller, Patricia, E-mail: sponselp@uw.edu; Department of Radiation Oncology, University of Washington Medical Center, Seattle, WA; Paravathaneni, Upendra

2013-07-01

The purpose of this report is to communicate a technique to match an electron field to the dose distribution of an Intensity-Modulated Radiation Therapy (IMRT) plan. A patient with multiple areas of squamous cell carcinoma over the scalp was treated using 60 Gy in 2.0-Gy fractions to the entire scalp and first echelon nodes with multiple 6-MV photon fields. To deliver an adequate dose to the scalp, a custom 1.0-cm bolus helmet was fashioned using a solid piece of aquaplast. Along with the IMRT scalp treatment, a left zygoma area was treated with electrons matching the anterior border of themore » IMRT dose distribution. The border was matched by creating a left lateral field with the multileaf collimator shaped to the IMRT dose distribution. The result indicated an adequate dose to the skin match between the IMRT plan and the electron field. Results were confirmed using optically stimulated luminescence placed at the skin match area, so that the dose matched the prescription within 10%.« less

Analysis of factors influencing the development of xerostomia during intensity-modulated radiotherapy.

PubMed

Randall, Ken; Stevens, Jason; Yepes, Juan Fernando; Randall, Marcus E; Kudrimoti, Mahesh; Feddock, Jonathan; Xi, Jing; Kryscio, Richard J; Miller, Craig S

2013-06-01

Factors influencing xerostomia during intensity-modulated radiation therapy (IMRT) were assessed. A 6-week study of 32 head and neck cancer (HNC) patients was performed. Subjects completed the Xerostomia Inventory (XI) and provided stimulated saliva (SS) at baseline, week 2 and at end of IMRT. Influence of SS flow rate (SSFR), calcium and mucin 5b (MUC5b) concentrations and radiation dose on xerostomia was determined. HNC subjects experienced mean SSFR decline of 36% by visit 2 (N = 27; P = .012) and 57% by visit 3 (N = 20; P = .0004). Concentrations of calcium and MUC5b increased, but not significantly during IMRT (P > .05). Xerostomia correlated most with decreasing salivary flow rate as determined by Spearman correlations (P < .04) and linear mixed models (P < .0001). Although IMRT is sparing to the parotid glands, it has an early effect on SSFR and the constituents in saliva in a manner that is associated with the perception of xerostomia. Copyright © 2013 Elsevier Inc. All rights reserved.