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https://www.readbyqxmd.com/read/28423530/patterns-of-failure-and-clinical-outcomes-of-definitive-radiotherapy-for-cervical-esophageal-cancer
#1
Lina Zhao, Yongchun Zhou, Yunfeng Mu, Guangjin Chai, Feng Xiao, Lina Tan, Steven H Lin, Mei Shi
PURPOSE: Because of the scarcity of cervical esophageal cancer (CEC), data for this disease entity is limited. We aim to evaluate the outcomes, prognostic factors and failure patterns of CEC treated by contemporary radiotherapy (RT). METHODS: We retrospectively analyzed 86 CEC patients consecutively treated between 2007 and 2015 by definitive RT with or without concurrent chemotherapy. RT was mainly delivered with Intensity Modulated Irradiation Therapy (IMRT) or Volumetric-Modulated Arc Therapy (VMAT)...
March 28, 2017: Oncotarget
https://www.readbyqxmd.com/read/28422421/results-of-a-10-year-survey-of-workload-for-10-treatment-vaults-at-a-high-throughput-comprehensive-cancer-center
#2
Ziad H Saleh, Jeho Jeong, Brian Quinn, James Mechalakos, Jean St Germain, Lawrence T Dauer
The workload for shielding purposes of modern linear accelerators (linacs) consists of primary and scatter radiation which depends on the dose delivered to isocenter (cGy) and leakage radiation which depends on the monitor units (MUs). In this study, we report on the workload for 10 treatment vaults in terms of dose to isocenter (cGy), monitor units delivered (MUs), number of treatment sessions (Txs), as well as, use factors (U) and modulation factors (CI) for different treatment techniques. The survey was performed for the years between 2006 and 2015 and included 16 treatment machines which represent different generations of Varian linear accelerators (6EX, 600C, 2100C, 2100EX, and TrueBeam) operating at different electron and x-ray energies (6, 9, 12, 16 and 20 MeV electrons and, 6 and 15 MV x-rays)...
April 19, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28410686/relations-between-doses-cumulated-in-bone-marrow-and-dose-delivery-techniques-during-radiation-therapy-of-cervical-and-endometrial-cancer
#3
Agata Jodda, Bartosz Urbański, Tomasz Piotrowski, Julian Malicki
PURPOSE: To compare normal tissue complication probability (NTCP) and average doses in the bone marrow (BM), obtained for five different radiotherapy delivery and planning strategies of cervical and endometrial cancer. MATERIAL/METHODS: 50 patients were taken to analysis. For each case, 3 different dose delivery techniques were used: 4-field, X15MV, 3DCRT; 7-field, X6MV, IMRT; and 2-arc, X6MV, VMAT. Two optimization scenarios were used for the IMRT and VMAT plans generation: with (+) and without (-) the inclusion of the BM as an optimized structure...
April 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28409420/single-fraction-spine-stereotactic-ablative-body-radiotherapy-with-volumetric-modulated-arc-therapy
#4
Matthew M Gestaut, Nitika Thawani, Sangroh Kim, Veera R Gutti, Sameer Jhavar, Niloyjyoti Deb, Andrew Morrow, Russell A Ward, Jason H Huang, Mehul Patel
This study investigated a single institution's experience with volumetric modulated arc therapy (VMAT) directed stereotactic ablative body radiotherapy (SABR) for vertebral metastases. From 2010 to 2014, 95 lesions of spinal metastases in 73 patients were treated with SABR using VMAT. Clinical local control, pain level, and use of steroid medication were employed to evaluate treatment responses. The majority (79%) of patients were treated with a radiation dose of 20 Gy in a single fraction. However, when normal tissue constraints could not be achieved, the dose was reduced to 18 Gy (11%) or 16 Gy (8%) in 1 fraction...
April 13, 2017: Journal of Neuro-oncology
https://www.readbyqxmd.com/read/28402279/intensity-modulated-radiotherapy-with-fixed-collimator-jaws-for-locoregional-left-sided-breast-cancer-irradiation
#5
Juanqi Wang, Zhaozhi Yang, Weigang Hu, Zhi Chen, Xiaoli Yu, Xiaomao Guo
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...
March 28, 2017: Oncotarget
https://www.readbyqxmd.com/read/28397968/trajectory-optimization-in-radiotherapy-using-sectioning-torus
#6
Christopher Barry Locke, Karl Kenneth Bush
PURPOSE: A challenging problem in trajectory optimization for radiotherapy is properly handling the synchronization of the medical accelerators dynamic delivery. The initial coarse sampling of control points implemented in a Progressive Resolution Optimization type approach (VMAT) routinely results in MLC aperture forming contention issues as the sampling resolution increases. This work presents an approach to optimize continuous, beam-on radiation trajectories through exploration of the anatomical topology present in the patient and formation of a novel dual-metric graph optimization problem...
April 11, 2017: Medical Physics
https://www.readbyqxmd.com/read/28395504/influence-of-jaw-tracking-in-intensity-modulated-and-volumetric-modulated-arc-radiotherapy-for-head-and-neck-cancers-a-dosimetric-study
#7
Karthick Raj Mani, Sagar Upadhayay, K J Maria Das
PURPOSE: 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. MATERIALS AND METHODS: 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...
March 2017: Radiation Oncology Journal
https://www.readbyqxmd.com/read/28384262/dosimetric-effects-of-sectional-adjustments-of-collimator-angles-on-volumetric-modulated-arc-therapy-for-irregularly-shaped-targets
#8
Beom Seok Ahn, So-Yeon Park, Jong Min Park, Chang Heon Choi, Minsoo Chun, Jung-In Kim
PURPOSE: To calculate an optimal collimator angle at each of sectional arcs in a full-arc volumetric modulated arc therapy (VMAT) plan and evaluate dosimetric quality of these VMAT plans comparing full-arc VMAT plans with a fixed collimator angle. METHODS: Seventeen patients who had irregularly-shaped target in abdominal, head and neck, and chest cases were selected retrospectively. To calculate an optimal collimator angle at each of sectional arcs in VMAT, integrated MLC apertures which could cover all shapes of target determined by beam's-eye view (BEV) within angular sections were obtained for each VMAT plan...
2017: PloS One
https://www.readbyqxmd.com/read/28383157/development-of-a-novel-low-radiation-absorbent-lok-bar-to-reduce-x-ray-scattering-and-absorption-in-rapidarc-%C3%A2-treatment-planning-and-dose-delivery
#9
Hajime Monzen, Kazuki Kubo, Mikoto Tamura, Masaru Hayakawa, Yasumasa Nishimura
We developed a novel low-radiation-absorbent lok-bar (HM-bar) that is used to secure the immobilizers to the couch. The aim of this study was to investigate the X-ray scattering and absorption properties of the HM-bar in computed tomography (CT) simulation and radiotherapy dose delivery using the Varian Exact™ lok-bar (VL-bar) as a benchmark. CT images were obtained with or without lok-bar, and then each image was visually evaluated for artifacts. The attenuation rates for each lok-bar were measured using a farmer-type ionization chamber (PTW30013) and the I'mRT phantom (IBA Dosimetry GmbH)...
April 6, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28373447/neurovascular-bundle-infiltration-can-explain-local-relapses-using-conformal-radiotherapy-of-prostate-cancer
#10
Andreas K Johansson, Bo Lennernäs, Ulf Isacsson
AIM: To quantify the impact of decreased margins for two treatment techniques, three-dimensional conformal radiotherapy (3D-CRT) and volumetric-modulated arc therapy (VMAT), on local control in curative treatment of prostate cancer. MATERIALS AND METHODS: The planning target volume (PTV) margins were decreased in steps of 1 mm from 10 to 1 mm. Treatment plans using 3D-CRT and VMAT technique were produced for all margin sizes and the dose to the neuro vascular bundles (NVB), that was not included in the PTV, was investigated...
April 2017: Anticancer Research
https://www.readbyqxmd.com/read/28371377/validation-of-a-gpu-based-3d-dose-calculator-for-modulated-beams
#11
Saeed Ahmed, Dylan Hunt, Jeff Kapatoes, Robert Hayward, Geoffrey Zhang, Eduardo G Moros, Vladimir Feygelman
A superposition/convolution GPU-accelerated dose computation algorithm (the Calculator) has been recently incorporated into commercial software. The algorithm requires validation prior to clinical use. Three photon energies were examined: conventional 6 MV and 15 MV, and 10 MV flattening filter free (10 MVFFF). For a set of IMRT and VMAT plans based on four of the five AAPM Practice Guideline 5a downloadable datasets, ion chamber (IC) measurements were performed on the water-equivalent phantoms. The average difference between the Calculator and IC was -0...
March 29, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28370002/angular-under-sampling-effect-on-vmat-dose-calculation-an-analysis-and-a-solution-strategy
#12
Ji-Yeon Park, FeiFei Li, Jonathan Li, Darren Kahler, Justin C Park, Guanghua Yan, Chihray Liu, Bo Lu
PURPOSE: Most VMAT algorithms compute the dose on discretized apertures with small angular separations for practical reasons. However, machines deliver the VMAT dose with a continuously moving MLC and gantry and a continuously changing dose rate. The computed dose can deviate from the delivered dose, especially if no, or loose, MLC movement constraints are applied for the VMAT optimization. The goal of this paper is to establish a simplified mathematical model to analyze the discrepancy between the VMAT plan calculation dose and the delivered dose and to provide a reasonable solution for clinical implementation...
April 1, 2017: Medical Physics
https://www.readbyqxmd.com/read/28358667/optimizing-sabr-delivery-for-synchronous-multiple-lung-tumors-using-volumetric-modulated-arc-therapy
#13
Hilâl Tekatli, Shyama U Tetar, Timothy K Nguyen, Andrew Warner, Wilko F Verbakel, David A Palma, Max Dahele, Stewart Gaede, Cornelis Haasbeek, Femke O Spoelstra, Patricia F de Haan, Ben J Slotman, Suresh Senan
BACKGROUND: Volumetric-modulated arc therapy (VMAT) delivery for stereotactic ablative radiotherapy (SABR) of multiple lung tumors allows for faster treatments. We report on clinical outcomes and describe a general approach for treatment planning. MATERIAL AND METHODS: Patients undergoing multi iso-center VMAT-based SABR for ≥2 lung lesions between 2009 and 2014 were identified from the VU University Medical Center and London Health Sciences Centre. Patients were eligible if the start date of the SABR treatment for the different lesions was within a time range of 30 days...
April 2017: Acta Oncologica
https://www.readbyqxmd.com/read/28343538/accelerated-hypofractionated-adjuvant-whole-breast-radiation-with-simultaneous-integrated-boost-using-volumetric-modulated-arc-therapy-for-early-breast-cancer-a-phase-i-ii-dosimetric-and-clinical-feasibility-study-from-a-tertiary-cancer-care-centre-of-india
#14
Dodul Mondal, Pramod Kumar Julka, Daya Nand Sharma, Manisha Jana, Macharla Anjaneyelu Laviraj, Suryanarayan Vs Deo, Soumyajit Roy, Randeep Guleria, Goura K Rath
BACKGROUND: Hypofractionation has become standard of care after Breast Conserving Therapy (BCT) in many European and few others western countries. Though still debatable, tumor cavity boost is routinely practised in our centre. Hypofractionation is not yet the current standard of practice in Asian countries. Employing hypofractionation and simultaneous integrated boost to lumpectomy cavity with conformal technique is not the current practice in this region. Hence the study was performed to see whether accelerated hypofractionation and simultaneous boost can be combined using volumetric modulated arc therapy (VMAT) in treating early breast cancer (EBC) patients...
March 2017: Journal of the Egyptian National Cancer Institute
https://www.readbyqxmd.com/read/28341061/vmat-plus-a-few-computer-optimized-non-coplanar-imrt-beams-vmat-tested-for-liver-sbrt
#15
Abdul Wahab M Sharfo, Maarten L P Dirkx, Sebastiaan Breedveld, Alejandra Méndez Romero, Ben J M Heijmen
PURPOSE: To propose a novel treatment approach, designated VMAT+, involving addition of <5 IMRT beams with computer-optimized non-coplanar orientations to VMAT, and evaluate it for liver Stereotactic Body Radiation Therapy (SBRT). VMAT+ is investigated as an alternative for (1) coplanar VMAT and (2) multi-beam non-coplanar treatment. METHODS/MATERIALS: For fifteen patients with liver metastases, VMAT+ plans were compared with (1) dual-arc VMAT and (2) 25-beam, non-coplanar treatment with computer-optimized beam orientations (25-NCP)...
March 22, 2017: Radiotherapy and Oncology: Journal of the European Society for Therapeutic Radiology and Oncology
https://www.readbyqxmd.com/read/28339918/can-clinically-relevant-dose-errors-in-patient-anatomy-be-detected-by-gamma-passing-rate-or-modulation-complexity-score-in-volumetric-modulated-arc-therapy-for-intracranial-tumors
#16
Shingo Ohira, Yoshihiro Ueda, Masaru Isono, Akira Masaoka, Misaki Hashimoto, Masayoshi Miyazaki, Masaaki Takashina, Masahiko Koizumi, Teruki Teshima
We investigated whether methods conventionally used to evaluate patient-specific QA in volumetric-modulated arc therapy (VMAT) for intracranial tumors detect clinically relevant dosimetric errors. VMAT plans with coplanar arcs were designed for 37 intracranial tumors. Dosimetric accuracy was validated by using a 3D array detector. Dose deviations between the measured and planned doses were evaluated by gamma analysis. In addition, modulation complexity score for VMAT (MCSv) for each plan was calculated. Three-dimensional dose distributions in patient anatomy were reconstructed using 3DVH software, and clinical deviations in dosimetric parameters between the 3DVH doses and planned doses were calculated...
March 3, 2017: Journal of Radiation Research
https://www.readbyqxmd.com/read/28339108/very-high-energy-electron-vhee-beams-in-radiation-therapy-treatment-plan-comparison-between-vhee-vmat-and-ppbs
#17
Emil Schüler, Kjell Eriksson, Elin Hynning, Steven L Hancock, Susan M Hiniker, Magdalena Bazalova-Carter, Tony Wong, Quynh-Thu Le, Billy W Loo, Peter G Maxim
PURPOSE: The aim of this study was to evaluate the performance of very high energy electron beams (VHEE) beams in comparison to clinically derived treatment plans generated with volumetric modulated arc therapy (VMAT) and proton pencil beam scanning (PPBS) technology. We developed a custom optimization script that could be applied automatically across modalities to eliminate operator bias during IMRT optimization. METHODS: Four clinical cases were selected (prostate cancer, lung cancer, pediatric brain tumor, and head and neck cancer (HNC))...
March 24, 2017: Medical Physics
https://www.readbyqxmd.com/read/28338854/comparison-of-the-peripheral-doses-from-different-imrt-techniques-for-pediatric-head-and-neck-radiation-therapy
#18
Masahiko Toyota, Yasumasa Saigo, Kenta Higuchi, Takuya Fujimura, Chihaya Koriyama, Takashi Yoshiura, Suminori Akiba
Intensity-modulated radiation therapy (IMRT) can deliver high and homogeneous doses to the target area while limiting doses to organs at risk. We used a pediatric phantom to simulate the treatment of a head and neck tumor in a child. The peripheral doses were examined for three different IMRT techniques [dynamic multileaf collimator (DMLC), segmental multileaf collimator (SMLC) and volumetric modulated arc therapy (VMAT)]. Peripheral doses were evaluated taking thyroid, breast, ovary and testis as the points of interest...
February 25, 2017: Radiation Protection Dosimetry
https://www.readbyqxmd.com/read/28318936/vector-model-supported-approach-in-prostate-plan-optimization
#19
Eva Sau Fan Liu, Vincent Wing Cheung Wu, Benjamin Harris, Margot Lehman, David Pryor, Lawrence Wing Chi Chan
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...
March 17, 2017: Medical Dosimetry: Official Journal of the American Association of Medical Dosimetrists
https://www.readbyqxmd.com/read/28318101/individual-volume-based-3d-gamma-indices-for-pretreatment-vmat-qa
#20
Jinling Yi, Ce Han, Xiaomin Zheng, Yongqiang Zhou, Zhenxiang Deng, Congying Xie, Xiance Jin, Fu Jin
Although gamma analysis is still a widely accepted quantitative tool to analyze and report patient-specific QA for intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT), the correlation between the 2D percentage gamma passing rate (%GP), and the clinical dosimetric difference for IMRT and VMAT has been questioned. The purpose of this study was to investigate the feasibility of individual volume-based 3D gamma indices for pretreatment VMAT QA. Percentage dosimetric errors (%DE) of dose-volume histogram metrics (includes target volumes and organ at risks) between the treatment planning system and QA-reconstructed dose distribution, %GPs for individual volume and global gamma indices, as well their correlations and sensitivities were investigated for one- and two-arc VMAT plans...
March 20, 2017: Journal of Applied Clinical Medical Physics
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