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imrt commissioning

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https://www.readbyqxmd.com/read/28438431/phantom-to-clinic-development-of-hypofractionated-stereotactic-body-radiotherapy-for-early-stage-glottic-laryngeal-cancer
#1
Chuxiong Ding, Stephen G Chun, Baran D Sumer, Lucien A Nedzi, Ramzi E Abdulrahman, John S Yordy, Pam Lee, Brian Hrycushko, Timothy D Solberg, Chul Ahn, Robert D Timmerman, David L Schwartz
The purpose of this study was to commission and clinically test a robotic stereotactic delivery system (CyberKnife, Sunnyvale, CA) to treat early-stage glottic laryngeal cancer. We enrolled 15 patients with cTis-T2N0M0 carcinoma of the glottic larynx onto an institutional review board (IRB)-approved clinical trial. Stereotactic body radiotherapy (SBRT) plans prescribed 45 Gy/10 fractions to the involved hemilarynx. SBRT dosimetry was compared with (1) standard carotid-sparing laryngeal intensity-modulated radiation therapy (IMRT) and (2) selective hemilaryngeal IMRT...
April 21, 2017: Medical Dosimetry: Official Journal of the American Association of Medical Dosimetrists
https://www.readbyqxmd.com/read/28405106/evaluation-of-intensity-modulated-radiation-therapy-delivery-system-using-a-volumetric-phantom-on-the-basis-of-the-task-group-119-report-of-american-association-of-physicists-in-medicine
#2
Raphaela Avgousti, Christina Armpilia, Ioannis Floros, Christos Antypas
The current work describes the implementation of the American Association of Physicists in Medicine (AAPM)'s Task Group 119 report on a volumetric phantom (Delta(4), Scandidos, Uppsala, Sweden) following the stated dose goals, to evaluate the step-and-shoot intensity modulated radiation therapy (IMRT) system. Delta(4) consists of diode detectors, lying on two crossed planes, measuring the delivered dose, and providing two-dimensional dosimetric information. Seven plans of different goals and complexity were performed, with individual structure sets...
January 2017: Journal of Medical Physics
https://www.readbyqxmd.com/read/28300374/efficient-independent-planar-dose-calculation-for-fff-imrt-qa-with-a-bivariate-gaussian-source-model
#3
Feifei Li, Ji-Yeon Park, Brendan Barraclough, Bo Lu, Jonathan Li, Chihray Liu, Guanghua Yan
The aim of this study is to perform a direct comparison of the source model for photon beams with and without flattening filter (FF) and to develop an efficient independent algorithm for planar dose calculation for FF-free (FFF) intensity-modulated radiotherapy (IMRT) quality assurance (QA). The source model consisted of a point source modeling the primary photons and extrafocal bivariate Gaussian functions modeling the head scatter, monitor chamber backscatter, and collimator exchange effect. The model parameters were obtained by minimizing the difference between the calculated and measured in-air output factors (Sc )...
March 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28297446/initial-clinical-experience-with-arccheck-for-imrt-vmat-qa
#4
Michalis Aristophanous, Yelin Suh, Pai C Chi, Luke J Whittlesey, Scott LaNeave, Mary K Martel
Many devices designed for the purpose of performing patient-specific IMRT/VMAT QA are commercially available. In this work we report our experience and initial clinical results with the ArcCHECK. The ArcCHECK consists of a cylindrical array of diode detectors measuring entry and exit doses. The measured result is a cumulative dose displayed as a 2D matrix. The detector array requires both an absolute dose calibration, and a calibration of the detector response, relative to each other. In addition to the calibrations suggested by the manufacturer, various tests were performed in order to assess its stability and performance prior to clinical introduction...
September 2016: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28297445/implementation-of-a-double-gaussian-source-model-for-the-beamnrc-monte-carlo-code-and-its-influence-on-small-fields-dose-distributions
#5
Edgardo Doerner, Paola Caprile
The shape of the radiation source of a linac has a direct impact on the delivered dose distributions, especially in the case of small radiation fields. Traditionally, a single Gaussian source model is used to describe the electron beam hitting the target, although different studies have shown that the shape of the electron source can be better described by a mixed distribution consisting of two Gaussian components. Therefore, this study presents the implementation of a double Gaussian source model into the BEAMnrc Monte Carlo code...
September 2016: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28297306/epid-based-dosimetry-to-verify-imrt-planar-dose-distribution-for-the-as1200-epid-and-fff-beams
#6
Narges Miri, Peter Keller, Benjamin J Zwan, Peter Greer
We proposed to perform a basic dosimetry commissioning on a new imager system, the Varian aS1200 electronic portal imaging device (EPID) and TrueBeam 2.0 linear accelerator for flattened (FF) and flattening filter-free (FFF) beams, then to develop an image-based quality assurance (QA) model for verification of the system delivery accuracy for intensity-modulated radiation therapy (IMRT) treatments. For dosimetry testing, linearity of dose response with MU, imager lag, and effectiveness of backscatter shielding were investigated...
November 2016: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28291929/implementation-of-the-validation-testing-in-mppg-5-a-commissioning-and-qa-of-treatment-planning-dose-calculations-megavoltage-photon-and-electron-beams
#7
Dustin J Jacqmin, Jeremy S Bredfeldt, Sean P Frigo, Jennifer B Smilowitz
The AAPM Medical Physics Practice Guideline (MPPG) 5.a provides concise guidance on the commissioning and QA of beam modeling and dose calculation in radiotherapy treatment planning systems. This work discusses the implementation of the validation testing recommended in MPPG 5.a at two institutions. The two institutions worked collaboratively to create a common set of treatment fields and analysis tools to deliver and analyze the validation tests. This included the development of a novel, open-source software tool to compare scanning water tank measurements to 3D DICOM-RT Dose distributions...
January 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28274405/state-of-dose-prescription-and-compliance-to-international-standard-icru-83-in-intensity-modulated-radiation-therapy-among-academic-institutions
#8
MULTICENTER STUDY
Indra J Das, Aaron Andersen, Zhe Jay Chen, Andrea Dimofte, Eli Glatstein, Jeremy Hoisak, Long Huang, Mark P Langer, Choonik Lee, Matthew Pacella, Richard A Popple, Roger Rice, Jennifer Smilowitz, Patricia Sponseller, Timothy Zhu
PURPOSE: The purpose of this study was to evaluate dose prescription and recording compliance to international standard (International Commission on Radiation Units & Measurements [ICRU]-83) in patients treated with intensity modulated radiation therapy (IMRT) among academic institutions. METHODS AND MATERIALS: Ten institutions participated in this study to collect IMRT data to evaluate compliance to ICRU-83. Under institutional review board clearance, data from 5094 patients-including treatment site, technique, planner, physician, prescribed dose, target volume, monitor units, planning system, and dose calculation algorithm-were collected anonymously...
March 2017: Practical Radiation Oncology
https://www.readbyqxmd.com/read/28255386/variation-in-uterus-position-prior-to-brachytherapy-of-the-cervix-a-case-report
#9
M T Georgescu, R Anghel
Rationale: brachytherapy is administered in the treatment of patients with locally advanced cervical cancer following chemoradiotherapy. Lack of local anatomy evaluation prior to this procedure might lead to the selection of an inappropriate brachytherapy applicator, increasing the risk of side effects (e.g. uterus perforation, painful procedure ...). Objective: To assess the movement of the uterus and cervix prior to brachytherapy in patients with gynecological cancer, in order to select the proper type of brachytherapy applicator...
January 2017: Journal of Medicine and Life
https://www.readbyqxmd.com/read/28243402/an-analytical-method-to-calculate-phantom-scatter-factor-for-photon-beam-accelerators
#10
Mohammad Javad Tahmasebi Birgani, Nahid Chegeni, Mohammad Ali Behrooz, Marziyeh Bagheri, Amir Danyaei, Azin Shamsi
INTRODUCTION: One of the important input factors in the commissioning of the radiotherapy treatment planning systems is the phantom scatter factor (Sp) which requires the same collimator opening for all radiation fields. In this study, we have proposed an analytical method to overcome this issue. METHODS: The measurements were performed using Siemens Primus Plus with photon energy 6 MV for field sizes from 5×5cm(2) to 40×40cm(2). Phantom scatter factor was measured through the division of total scatter output factors (Scp), and collimator scatter factor (Sc)...
January 2017: Electronic Physician
https://www.readbyqxmd.com/read/28048924/mo-b-brb-02-3d-dosimetry-in-the-clinic-imrt-technique-validation-in-sweden
#11
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/28048796/mo-fg-campus-jep2-04-comparison-study-for-ct-and-mr-only-prostate-imrt-treatment-planning-a-framework-for-the-estimation-of-relative-contribution-of-body-contour-discrepancies-tissue-stratification-and-hu-red-conversion-to-the-overall-dose-difference
#12
M Maspero, P R Seevinck, G Schubert, M Hoesl, G J Meijer, M A Viergever, Jjw Lagendijk, Cat van den Berg
PURPOSE: To compare dose of prostate IMRT plans on CT vs MR-based pseudo-CT (pCT). A framework is demonstrated to isolate various confounding factors causing dose differences. This approach will be valuable for medical physicists interested in commissioning strategy of MR-only dose planning. METHODS: A retrospective study was conducted on fourteen prostate patients that underwent CT and MRI scans. MR was equipped with an in-house-developed flat table-top and coil support...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048700/tu-d-bra-00-treatment-planning-system-commissioning-and-qa
#13
Greg Salomons
INTRODUCTION: Treatment planning systems (TPS) are a cornerstone of modern radiation therapy. Errors in their commissioning or use can have a devastating impact on many patients. To support safe and high quality care, medical physicists must conduct efficient and proper commissioning, good clinical integration, and ongoing quality assurance (QA) of the TPS. AAPM Task Group 53 and related publications have served as seminal benchmarks for TPS commissioning and QA over the past two decades...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048602/su-f-t-262-commissioning-varian-portal-dosimetry-for-epid-based-patient-specific-qa-in-a-non-aria-environment
#14
M Schmidt, N Knutson, J Herrington, M Price
PURPOSE: Development of an in-house program facilitates a workflow that allows Electronic Portal Imaging Device (EPID) patient specific quality assurance (QA) measurements to be acquired and analyzed in the Portal Dosimetry Application (Varian Medical Systems, Palo Alto, CA) using a non-Aria Record and Verify (R&V) system (MOSAIQ, Elekta, Crawley, UK) to deliver beams in standard clinical treatment mode. METHODS: Initial calibration of an in-house software tool includes characterization of EPID dosimetry parameters by importing DICOM images of varying delivered MUs to determine linear mapping factors in order to convert image pixel values to Varian-defined Calibrated Units (CU)...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048590/we-ab-brb-03-real-time-volumetric-scintillation-dosimetry-for-radiation-therapy
#15
S Beddar
Despite widespread IMRT treatments at modern radiation therapy clinics, precise dosimetric commissioning of an IMRT system remains a challenge. In the most recent report from the Radiological Physics Center (RPC), nearly 20% of institutions failed an end-to-end test with an anthropomorphic head and neck phantom, a test that has rather lenient dose difference and distance-to-agreement criteria of 7% and 4 mm. The RPC report provides strong evidence that IMRT implementation is prone to error and that improved quality assurance tools are required...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048274/mo-b-brb-03-3d-dosimetry-in-the-clinic-validating-special-techniques
#16
T Juang
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/28048260/su-f-p-37-implementation-of-an-end-to-end-qa-test-of-the-radiation-therapy-imaging-planning-and-delivery-process-to-identify-and-correct-possible-sources-of-deviation
#17
F Salinas Aranda, V Suarez, S Arbiser, R Sansogne
PURPOSE: To implement an end-to-end QA test of the radiation therapy imaging, planning and delivery process, aimed to assess the dosimetric agreement accuracy between planned and delivered treatment, in order to identify and correct possible sources of deviation. To establish an internal standard for machine commissioning acceptance. METHODS: A test involving all steps of the radiation therapy: imaging, planning and delivery process was designed. The test includes analysis of point dose and planar dose distributions agreement between TPS calculated and measured dose...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048146/tu-ab-brc-04-commissioning-of-a-new-mlc-model-for-the-gepts-monte-carlo-system-a-model-based-on-the-leaf-and-interleaf-effective-density
#18
O Chibani, F Tahanout, C Ma
PURPOSE: To commission a new MLC model for the GEPTS Monte Carlo system. The model is based on the concept of leaves and interleaves effective densities METHODS: GEPTS is a Monte Carlo system to be used for external beam planning verification. GEPTS incorporates detailed photon and electron transport algorithms (Med.Phys. 29, 2002, 835). A new GEPTS model for the Varian Millennium MLC is presented. The model accounts for: 1) thick (1 cm) and thin (0.5 cm) leaves, 2) tongue-and-groove design, 3) High-Transmission (HT) and Low-Transmission (LT) interleaves, and 4) rounded leaf end...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048038/tu-d-bra-01-tps-commissioning-and-qa-planning-and-monitoring
#19
G Salomons
INTRODUCTION: Treatment planning systems (TPS) are a cornerstone of modern radiation therapy. Errors in their commissioning or use can have a devastating impact on many patients. To support safe and high quality care, medical physicists must conduct efficient and proper commissioning, good clinical integration, and ongoing quality assurance (QA) of the TPS. AAPM Task Group 53 and related publications have served as seminal benchmarks for TPS commissioning and QA over the past two decades...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28047973/tu-d-201-05-validation-of-treatment-planning-dose-calculations-experience-working-with-mppg-5-a
#20
J Xue, J Park, L Kim, P Balter, J Ohrt, S Kirsner, C Wang, G Ibbott
PURPOSE: Newly published medical physics practice guideline (MPPG 5.a.) has set the minimum requirements for commissioning and QA of treatment planning dose calculations. We present our experience in the validation of a commercial treatment planning system based on MPPG 5.a. METHODS: In addition to tests traditionally performed to commission a model-based dose calculation algorithm, extensive tests were carried out at short and extended SSDs, various depths, oblique gantry angles and off-axis conditions to verify the robustness and limitations of a dose calculation algorithm...
June 2016: Medical Physics
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