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https://www.readbyqxmd.com/read/28102956/experimental-verification-of-4d-monte-carlo-simulations-of-dose-delivery-to-a-moving-anatomy
#1
Sara Gholampourkashi, Miro Vujicic, Jason Belec, Joanna E Cygler, Emily Heath
PURPOSE: To evaluate a novel 4D Monte Carlo simulation tool by comparing calculations to physical measurements using a respiratory motion phantom. METHODS: We used a dynamic Quasar phantom in both stationary and breathing states (sinusoidal motion of amplitude of 1.8 cm and period of 3.3 s) for dose measurements on an Elekta Agility linear accelerator. Gafchromic EBT3 film and the RADPOS 4D dosimetry system were placed inside the lung insert of the phantom to measure dose profiles and point-dose values at the center of the spherical tumor inside the insert...
January 2017: Medical Physics
https://www.readbyqxmd.com/read/28102944/a-simple-and-robust-trajectory-based-stereotactic-radiosurgery-treatment
#2
Byron Wilson, Karl Otto, Ermias Gete
INTRODUCTION: We present a Trajectory-based Volumetric Modulated Arc Therapy (TVMAT) technique for Stereotactic Radiosurgery (SRS) that takes advantage of a modern linacs ability to modulate dose rate and move the couch dynamically. In addition, we investigate the quality of the developed TVMAT method and the dosimetric accuracy of the technique. METHODS: The main feature of the TVMAT technique is a standard beam trajectory formed by dynamic motion of the treatment couch and the linac gantry...
January 2017: Medical Physics
https://www.readbyqxmd.com/read/28100239/elective-breast-radiotherapy-including-level-i-and-ii-lymph-nodes-a-planning-study-with-the-humeral-head-as-planning-risk-volume
#3
Kathrin Surmann, Jorien van der Leer, Tammy Branje, Maurice van der Sangen, Maarten van Lieshout, Coen W Hurkmans
BACKGROUND: The aim of this study was to assess the dose to the humeral head planning risk volume with the currently used high tangential fields (HTF) and compare different planning techniques for breast radiotherapy including axillary level I and II lymph nodes (PTVn) while sparing the humeral head. METHODS: Ten patients with left-sided breast cancer were enrolled in a planning study with 16 fractions of 2.66 Gy. Four planning techniques were compared: HTF, HTF with sparing of the humeral head, 6-field IMRT with sparing of the humeral head and VMAT with sparing of the humeral head...
January 18, 2017: Radiation Oncology
https://www.readbyqxmd.com/read/28089479/estimation-of-radiation-induced-secondary-cancer-risks-for-early-stage-non-small-cell-lung-cancer-patients-after-stereotactic-body-radiation-therapy
#4
Chunhui Han, Timothy E Schultheiss, Jeffrey Y C Wong
PURPOSE: In this study, we evaluated radiation-induced secondary lung cancer risks for the lung and the breast from stereotactic body radiation therapy treatment of early-stage non-small cell lung cancer with different radiation therapy treatment modalities. METHODS AND MATERIALS: Ten patients (5 men and 5 women) with early-stage non-small cell lung cancer who received definitive stereotactic body radiation therapy treatments were retrospectively selected. For each patient, two 3-dimensional conformal radiation therapy (3D-CRT) plans using 6- and 10-MV photons, respectively; a helical tomotherapy (HT) plan; and 2 volumetric modulated arc therapy (VMAT) plans using 1 and 2 arcs, respectively, were generated...
October 19, 2016: Practical Radiation Oncology
https://www.readbyqxmd.com/read/28079525/a-model-based-3d-patient-specific-pre-treatment-qa-method-for-vmat-using-the-epid
#5
Peter M McCowan, Ganiyu Asuni, Timothy van Beek, Eric Van Uytven, Kaden Kujanpaa, Boyd McCurdy
This study reports the development and validation of the first model-based, 3D patient dose reconstruction method for pre-treatment quality assurance using EPID images. The method is also investigated for sensitivity to potential MLC delivery errors. Each cine-mode EPID image acquired during plan delivery was processed using a previously developed back-projection dose reconstruction model providing a 3D dose estimate on the CT simulation data. Validation was carried out using 24 SBRT-VMAT patient plans by comparing: 1) ion chamber point dose measurements in a solid water phantom, 2) the treatment planning system (TPS) predicted 3D dose to the EPID reconstructed 3D dose in a solid water phantom, and 3) the TPS predicted 3D dose to the EPID and our forward predicted reconstructed 3D dose in the patient (CT data)...
January 12, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28079260/an-experimentally-validated-couch-and-mlc-tracking-simulator-used-to-investigate-hybrid-couch-mlc-tracking
#6
Jakob Toftegaard, Rune Hansen, Thomas Ravkilde, Kristijan Macek, Per Rugaard Poulsen
PURPOSE/OBJECTIVE: Couch and MLC tracking are two novel techniques to mitigate intrafractional tumor motion on a conventional linear accelerator, but both techniques still have residual dosimetric errors. Here, we first propose and experimentally validate a software tool to simulate couch and MLC tracking, and then use the simulator to study hybrid couch-MLC tracking for improved tracking performance. MATERIALS AND METHODS: The tracking simulator requires a treatment plan and a motion trajectory as input and simulates the delivered monitor units and motion of all accelerator parts as function of time...
January 12, 2017: Medical Physics
https://www.readbyqxmd.com/read/28077128/treatment-planning-comparison-of-impt-vmat-and-4%C3%AF-radiotherapy-for-prostate-cases
#7
Angelia Tran, Jingjing Zhang, Kaley Woods, Victoria Yu, Dan Nguyen, Gary Gustafson, Lane Rosen, Ke Sheng
BACKGROUND: Intensity-modulated proton therapy (IMPT), non-coplanar 4π intensity-modulated radiation therapy (IMRT), and volumetric-modulated arc therapy (VMAT) represent the most advanced treatment methods based on heavy ion and X-rays, respectively. Here we compare their performance for prostate cancer treatment. METHODS: Ten prostate patients were planned using IMPT with robustness optimization, VMAT, and 4π to an initial dose of 54 Gy to a clinical target volume (CTV) that encompassed the prostate and seminal vesicles, then a boost prescription dose of 25...
January 11, 2017: Radiation Oncology
https://www.readbyqxmd.com/read/28065699/evaluation-of-mlc-performance-in-vmat-and-dynamic-imrt-by-log-file-analysis
#8
José Olasolo-Alonso, Alejandro Vázquez-Galiñanes, Santiago Pellejero-Pellejero, José Fernando Pérez-Azorín
PURPOSE: This multi-institution study assessed the positioning accuracy of multileaf collimators (MLC) by analyzing log files. It determined the main machine parameters that affect MLC positioning errors for pre-TrueBeam (Clinac) and TrueBeam linacs. METHODS: Around 30,000 dIMRT and VMAT log files belonging to 6 linacs from 4 different centers were analyzed. An in-house software was used to calculate 95th percentile and RMS error values and their correlation with certain parameters such as maximum leaf speed, mean leaf speed and gantry angle...
January 5, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28061474/tomotherapy-as-an-adjuvant-treatment-for-gastroesophageal-junction-and-stomach-cancer-may-reduce-bowel-and-bone-marrow-toxicity-compared-to-intensity-modulated-radiotherapy-and-volumetric-modulated-arc-therapy
#9
Xin Wang, Yuan Tian, Yuan Tang, Zhi-Hui Hu, Jia-Jia Zhang, Gui-Shan Fu, Pan Ma, Hua Ren, Tao Zhang, Ning Li, Wen-Yang Liu, Hui Fang, Ye-Xiong Li, Jing Jin
PURPOSE: To compare dosimetric parameters of intensity-modulated radiotherapy (IMRT), volumetric-modulated arc therapy (VMAT) and tomotherapy (TOMO) in the adjuvant treatment of gastroesophageal junction (GEJ)/stomach cancer. The planning goal was to maintain high target coverage while keeping the dose to the bowel and bone marrow (BM) as low as possible. MATERIALS AND METHODS: After curative surgery, 16 patients with GEJ/stomach cancer were re-planned by coplanar IMRT (five fixed beam), VMAT (double-arc), and TOMO...
January 3, 2017: Oncotarget
https://www.readbyqxmd.com/read/28052046/fast-approximate-delivery-of-fluence-maps-for-imrt-and-vmat
#10
Marleen Balvert, David L Craft
In this article we provide a method to generate the trade-off between delivery time and fluence map matching quality for dynamically delivered fluence maps. At the heart of our method lies a mathematical programming model that, for a given duration of delivery, optimizes leaf trajectories and dose rates such that the desired fluence map is reproduced as well as possible. We begin with the single fluence map case and then generalize the model and the solution technique to the delivery of sequential fluence maps...
January 4, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28048927/mo-fg-bra-05-dosimetric-and-radiobiological-validation-of-respiratory-gating-in-conventional-and-hypofractionated-radiotherapy-of-the-lung-effect-of-dose-dose-rate-gating-window-and-breathing-pattern
#11
L Cervino, D Soultan, N Pettersson, A Yock, M Cornell, J Aguilera, J Murphy, B Gill, S Advani, V Moiseenko
PURPOSE: to evaluate the dosimetric and radiobiological consequences from having different gating windows, dose rates, and breathing patterns in gated VMAT lung radiotherapy. METHODS: A novel 3D-printed moving phantom with central high and peripheral low tracer uptake regions was 4D FDG-PET/CT-scanned using ideal, patient-specific regular, and irregular breathing patterns. A scan of the stationary phantom was obtained as a reference. Target volumes corresponding to different uptake regions were delineated...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048924/mo-b-brb-02-3d-dosimetry-in-the-clinic-imrt-technique-validation-in-sweden
#12
S Ceberg
: Full three-dimensional (3D) dosimetry using volumetric chemical dosimeters probed by 3D imaging systems has long been a promising technique for the radiation therapy clinic, since it provides a unique methodology for dose measurements in the volume irradiated using complex conformal delivery techniques such as IMRT and VMAT. To date true 3D dosimetry is still not widely practiced in the community; it has been confined to centres of specialized expertise especially for quality assurance or commissioning roles where other dosimetry techniques are difficult to implement...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048901/su-f-t-627-a-conformity-index-study-of-sbrt-plans-for-lung-cancer-patient
#13
Dengsong Zhu, Guoqing Fan, Chong Peng, Carlos Austerlitz
PURPOSE: To evaluate the conformity index for SBRT lung plan in Eclipse (version 11) treatment planning system. METHODS: In the Eclipse treatment planning system the conformity index was defined as VRI/TV, where VRI is prescription isodose surface, and TV is the target volume. In 1997, Van't Riet et al introduced TVRI/TV × TVRI/VRI as a conformal index, where TVRI is the target volume closed by the prescription isodose surface. We chose a lung cancer patient who was assigned to be treated with SBRT...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048889/su-f-p-64-the-impact-of-plan-complexity-parameters-on-the-plan-quality-and-deliverability-of-volumetric-modulated-arc-therapy-with-canonical-correlation-analysis
#14
X Jin, J Yi, C Xie
PURPOSE: To evaluate the impact of complexity indices on the plan quality and deliverability of volumetric modulated arc therapy (VMAT), and to determine the most significant parameters in the generation of an ideal VMAT plan. METHODS: A multi-dimensional exploratory statistical method, canonical correlation analysis (CCA) was adopted to study the correlations between VMAT parameters of complexity, quality and deliverability, as well as their contribution weights with 32 two-arc VMAT nasopharyngeal cancer (NPC) patients and 31 one-arc VMAT prostate cancer patients...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048885/mo-d-brb-03-quality-assurance-of-sbrt
#15
J Roper
: Increased use of SBRT and hypofractionation in radiation oncology practice has posted a number of challenges to medical physicist, ranging from planning, image-guided patient setup and on-treatment monitoring, to quality assurance (QA) and dose delivery. This symposium is designed to provide current knowledge necessary for the safe and efficient implementation of SBRT in various linac platforms, including the emerging digital linacs equipped with high dose rate FFF beams. Issues related to 4D CT, PET and MRI simulations, 3D/4D CBCT guided patient setup, real-time image guidance during SBRT dose delivery using gated/un-gated VMAT/IMRT, and technical advancements in QA of SBRT (in particular, strategies dealing with high dose rate FFF beams) will be addressed...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048874/su-f-t-616-comparison-of-different-techniques-using-rtog0631-guidelines-in-spine-sbrt
#16
H Acar, M Cebe, H Mabhouti, G Codel, P Pacaci, E Serin, E Sanli, N Kucuk, E Kucukmorkoc, M Doyuran, D Canoglu, A Altinok, H Caglar
PURPOSE: Stereotactic body radiosurgery (SBRT) for spine metastases involves irradiation using a single high dose fraction. The purpose of this study was to investigate a Hybrid VMAT/IMRT technique which combines volumetric modulated arc therapy (VMAT) and intensity modulated radiation therapy (IMRT) for spine SBRT in terms of its dosimetric quality and treatment efficiency using Radiation Therapy Oncology Group (RTOG) 0631 guidelines. METHODS: 7 fields IMRT, 2 full arcs VMAT and Hybrid VMAT/IMRT were created for ten previously treated patients...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048861/su-g-jep1-09-evaluation-of-transperineal-ultrasound-imaging-as-a-potential-solution-for-target-tracking-during-ablative-body-radiotherapy-for-prostate-cancer
#17
M Najafi, B Han, D Cooper, S Hancock, D Hristov
PURPOSE: Prostate SABR is emerging as a clinically viable, potentially cost effective alternative to prostate IMRT but its adoption is contingent on providing solutions for accurate tracking during beam delivery. Our goal is to evaluate the performance of the Clarity Autoscan ultrasound monitoring system for inter-fractional prostate motion tracking in both phantoms and in-vivo. METHODS: In-vivo evaluation was performed under IRB protocol to allow data collection in prostate patients treated with VMAT whereby prostate was imaged through the acoustic window of the perineum...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048850/su-g-brc-14-multi-lesion-multi-rx-brain-radiosurgery-with-novel-single-isocenter-technique
#18
N Honig, S Alani, A Schlocker, N Shtraus, A Kanner
PURPOSE: There is a strong trend to treat multiple brain metastases with radiosurgery rather than whole brain irradiation. This feasibility study investigates a novel planning technique for radio-surgical treatment of multiple brain lesions with differing dose prescriptions, a single isocenter, and dynamic conformal arcs. The novel technique will be compared to the well-established single-isocenter volumetric modulated arc therapy (VMAT) technique commonly used for treating brain lesions...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048778/su-f-t-101-insight-into-dosimetry-workload-and-planning-timelines-a-6-year-review-at-one-institution
#19
R Cardan, R Popple, H Smith, J Fiveash
PURPOSE: To elucidate realistic clinical treatment planning workload and timelines to improve understanding for patients, payers, and other institutions involved in radiotherapy processes. METHODS: A web based tool was developed using Oracle Express (Oracle Corp, Redwood City, CA) which allowed communication between the physicians and staff about the current state of the patient plan. For 6 years, all patient courses were logged and time-stamped in 22 discreet steps which detailed start and stop times for simulation, contouring, and treatment planning tasks...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048769/mo-fg-202-04-gantry-resolved-linac-qa-for-vmat-a-comprehensive-and-efficient-system-using-an-electronic-portal-imaging-device
#20
B J Zwan, M Barnes, J Hindmarsh, E Seymour, D J O'Connor, P J Keall, P B Greer
PURPOSE: To automate gantry-resolved linear accelerator (linac) quality assurance (QA) for volumetric modulated arc therapy (VMAT) using an electronic portal imaging device (EPID). METHODS: A QA system for VMAT was developed that uses an EPID, frame-grabber assembly and in-house developed image processing software. The system relies solely on the analysis of EPID image frames acquired without the presence of a phantom. Images were acquired at 8.41 frames per second using a frame grabber and ancillary acquisition computer...
June 2016: Medical Physics
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