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Gafchromic film

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https://www.readbyqxmd.com/read/29137808/geometric-and-dosimetric-accuracy-of-dynamic-tumor-tracking-during-volumetric-modulated-arc-therapy-using-a-gimbal-mounted-linac
#1
Tomohiro Ono, Yuki Miyabe, Kunio Takahashi, Mami Akimoto, Nobutaka Mukumoto, Yoshitomo Ishihara, Mitsuhiro Nakamura, Takashi Mizowaki, Masahiro Hiraoka
PURPOSE: The aim was to examine the feasibility of a dynamic tumor-tracking volumetric modulated arc therapy (DTT-VMAT) technique using a gimbal-mounted linac and assess its positional, mechanical and dosimetric accuracy. MATERIALS AND METHODS: DTT-VMAT was performed using a surrogated signal-based technique. The positional tracking accuracy was evaluated as the difference between the predicted and detected target positions for various wave patterns. Mechanical accuracy measurements included gantry, multileaf collimator (MLC) and gimbal positions...
November 11, 2017: Radiotherapy and Oncology: Journal of the European Society for Therapeutic Radiology and Oncology
https://www.readbyqxmd.com/read/29072852/the-effect-of-mepitel-film-on-acute-radiation-induced-skin-reactions-in-head-and-neck-cancer-patients-a-feasibility-study
#2
Hayley Wooding, Jing Yan, Ling Yuan, Te-Yu Chyou, Shanbao Gao, Iain Ward, Patries M Herst
OBJECTIVE: Mepitel Film significantly decreases acute radiation-induced skin reactions in breast cancer patients. Here we investigated the feasibility of using Mepitel Film in head and neck cancer patients (ACTRN12614000932662). METHODS: Out of a total of 36 head and neck cancer patients from New Zealand (NZ) (n=24) and China (n=12) recruited between June 2015 and December 2016, 33 patients complied with protocol. Of these, 11 NZ patients followed a management protocol; 11 NZ patients and 11 Chinese patients followed a prophylactic protocol...
October 26, 2017: British Journal of Radiology
https://www.readbyqxmd.com/read/29047456/a-reusable-osl-film-for-2d-radiotherapy-dosimetry
#3
Crijns Wouter, Vandenbroucke Dirk, Leblans Paul, Depuydt Tom
Optical stimulated luminescence (OSL) combines reusability, sub-mm resolution, and a linear dose response in a single radiation detection technology. Such a combination is currently lacking in radiotherapy dosimetry. But OSL-films have a strong energy dependent response to keV photons due to a relative high effective atomic number (Z eff). The current work studied the applicability of a 2D OSL-film with a reduced Z eff as (IMRT/VMAT) dosimeter. Based on their commercial OSL-film experience, Agfa Healthcare N...
October 19, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28988675/application-of-geant4-monte-carlo-simulation-in-dose-calculations-for-small-radiosurgical-fields
#4
Somayeh Gholami, Francesco Longo, Hassan Ali Nedaie, Alessio Berti, Mehdi Mousavi, Ali S Meigooni
The Geant4 toolkit was used to develop a Monte Carlo (MC)-based engine for accurate dose calculations in small radiation field sizes. The Geant4 toolkit (version 10.1.p02) was used to simulate 6-MV photon beam of a Varian2100C linear accelerator that is being used for stereotactic radiosurgery (SRS) treatment with small radiation fields. Geometric models of 3 in-house designed radiosurgical divergent cones, with the diameters of their projections at the isocenter being 10, 20, and 30 mm, were simulated. The accuracy of the MC simulation technique was examined by reproducing several different simulated dosimetric parameters of the primary beams with the experimental data...
October 4, 2017: Medical Dosimetry: Official Journal of the American Association of Medical Dosimetrists
https://www.readbyqxmd.com/read/28985954/experimental-verification-of-dose-enhancement-effects-in-a-lung-phantom-from-inline-magnetic-fields
#5
Bradley M Oborn, Maegan A Gargett, Trent J Causer, Sarah J Alnaghy, Nicholas Hardcastle, Peter E Metcalfe, Paul J Keall
BACKGROUND AND PURPOSE: To present experimental evidence of lung dose enhancement effects caused by strong inline magnetic fields. MATERIALS AND METHODS: A permanent magnet device was utilised to generate 0.95T-1.2T magnetic fields that encompassed two small lung-equivalent phantoms of density 0.3g/cm(3). Small 6MV and 10MV photon beams were incident parallel with the magnetic field direction and Gafchromic EBT3 film was placed inside the lung phantoms, perpendicular to the beam (experiment 1) and parallel to the beam (experiment 2)...
October 3, 2017: Radiotherapy and Oncology: Journal of the European Society for Therapeutic Radiology and Oncology
https://www.readbyqxmd.com/read/28940609/technical-note-scanning-of-parallel-plate-ionization-chamber-and-diamond-detector-for-measurements-of-water-dose-profiles-in-the-vicinity-of-a-narrow-x-ray-microbeam
#6
Nobuteru Nariyama
PURPOSE: Scanning of dosimeters facilitates dose distribution measurements with fine spatial resolutions. This paper presents a method of conversion of the scanning results to water-dose profiles and provides an experimental verification. METHODS: An Advanced Markus chamber and a diamond detector were scanned at a resolution of 6 μm near the beam edges during irradiation with a 25-μm-wide white narrow x-ray beam from a synchrotron radiation source. For comparison, GafChromic films HD-810 and HD-V2 were also irradiated...
September 22, 2017: Medical Physics
https://www.readbyqxmd.com/read/28930093/a-reusable-osl-film-for-2d-radiotherapy-dosimetry
#7
Wouter Crijns, Dirk Adelin Vandenbroucke, Paul Leblans, Tom Depuydt
Purpose Optical stimulated luminescence (OSL) combines reusability, sub-mm resolution, and a linear dose response in a single radiation detection technology. Such a combination is currently lacking in radiotherapy dosimetry. But OSL-films have a strong energy dependent response to keV photons due to a relative high effective atomic number (Zeff). The current work studied the applicability of a 2D OSL-film with a reduced Zeff as (IMRT/VMAT) dosimeter. Methods and Materials Based on their commercial OSL-film experience, Agfa Healthcare N...
September 20, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28891710/the-use-of-a-thyroid-shield-for-intraoral-anterior-oblique-occlusal-views-a-risk-based-approach
#8
Mark Worrall, Alison Menhinick, Donald J Thomson
OBJECTIVES: To estimate the radiation dose reduction to the thyroid for an anterior oblique occlusal view from the use of a thyroid shield, compare this with the variation in thyroid dose resulting from differences in examination positioning and discuss the additional considerations associated with the use of a thyroid shield before making a recommendation on their routine use for this examination. METHODS: Doses to the oral mucosa, the salivary glands, the thyroid, the extrathoracic airways, the oesophagus and the lungs were directly measured for anterior oblique occlusal X-rays of a Rando phantom with and without a thyroid shield using strips of calibrated XRQA Gafchromic film...
October 27, 2017: Dento Maxillo Facial Radiology
https://www.readbyqxmd.com/read/28885190/film-dosimetry-using-a-smart-device-camera-a-feasibility-study-for-point-dose-measurements
#9
Trent Aland, Ekta Jhala, Tanya Kairn, Jamie V Trapp
In this work, a methodology for using a smartphone camera, in conjunction with a light-tight box operating in reflective transmission mode, is investigated as a proof of concept for use as a film dosimetry system. An imaging system was designed to allow the camera of a smartphone to be used as a pseudo densitometer. Ten pieces of Gafchromic EBT3 film were irradiated to doses up to 16.89 Gy and used to evaluate the effects of reproducibility and orientation, as well as the ability to create an accurate dose response curve for the smartphone based dosimetry system, using all three colour channels...
September 8, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28843699/differential-dose-absorptions-for-various-biological-tissue-equivalent-materials-using-gafchromic-xr-qa2-film-in-diagnostic-radiology
#10
A Ahmed Alsadig, S Abbas, S Kandaiya, N A R Nik Noor Ashikin, M A Qaeed
Phantoms are devices that simulate human tissues including soft tissues, lungs, and bones in medical and health physics. The purpose of this work was to investigate the differential dose absorption in several commercially available low-cost materials as substitutes to human tissues using Gafchromic XR-QA2 film. The measurement of absorbed dose by different materials of various densities was made using the film to establish the relationship between the absorbed dose and the material density. Materials investigated included soft board materials, Perspex, chicken bone, Jeltrate, chalk, cow bone, marble, and aluminum, which have varying densities from 0...
November 2017: Applied Radiation and Isotopes
https://www.readbyqxmd.com/read/28840169/assessment-of-organ-and-effective-dose-when-using-region-of-interest-attenuators-in-cone-beam-ct-and-interventional-fluoroscopy
#11
Zhenyu Xiong, Sarath Vijayan, Stephen Rudin, Daniel R Bednarek
In some medical-imaging procedures using cone-beam CT (CBCT) and fluoroscopy, only the center of the field of view (FOV) may be needed to be visualized with optimal image quality. To reduce the dose to the patient while maintaining visualization of the entire FOV, a Cu attenuator with a circular aperture for the region of interest (ROI) is used. The potential organ and effective dose reductions of ROI imaging when applied to CBCT and interventional fluoroscopic procedures were determined using EGSnrc Monte Carlo code...
July 2017: Journal of Medical Imaging
https://www.readbyqxmd.com/read/28780318/detecting-anomalies-in-a-deliberately-biased-tomotherapy-plan-comparison-of-two-patient-specific-quality-assurance-processes-involving-arccheck-%C3%A2-and-gafchromic-%C3%A2-ebt3-films
#12
F Werlé, N Dehaynin, C Niederst, D Jarnet, M Gantier, D Karamanoukian, P Meyer
PURPOSE: This work proposes a comparative evaluation of two of our patient-specific quality assurance processes involving ArcCHECK(®) (Sun Nuclear) and Gafchromic(®) EBT3 films (Ashland) in order to determine which detector is able to most effectively detect an anomaly in a deliberately biased tomotherapy plan. MATERIAL AND METHODS: A complex clinical head and neck tomotherapy plan was deliberately biased by introducing six errors: multileaf collimator leaf positional errors by leaving one and two central leafs closed during the whole treatment, initial radiation angle errors (+0...
August 2, 2017: Cancer Radiothérapie: Journal de la Société Française de Radiothérapie Oncologique
https://www.readbyqxmd.com/read/28777468/technical-note-a-novel-quality-assurance-test-to-identify-gantry-angle-inaccuracies-in-respiratory-gated-vmat-treatments
#13
Emily Hubley, Michael Briscoe, Nicolas Ploquin, Greg Pierce
PURPOSE: During respiratory-gated volumetric-modulated arc therapy (VMAT), the radiation beam is turned off each time the target exits the gating window. At the same time, the gantry slows, stops, and rewinds before the beam is turned back on. A quality assurance (QA) test was developed to detect inaccuracies in the gantry angle position between beam-off and beam-on events during respiratory-gated VMAT. METHODS: Strips of Gafchromic™ EBT3 film were taped to the surface of a Capthan(®) 504 phantom mounted at isocenter...
October 2017: Medical Physics
https://www.readbyqxmd.com/read/28750023/the-combination-of-the-error-correction-methods-of-gafchromic-ebt3-film
#14
Yinghui Li, Lixin Chen, Jinhan Zhu, Xiaowei Liu
PURPOSE: The aim of this study was to combine a set of methods for use of radiochromic film dosimetry, including calibration, correction for lateral effects and a proposed triple-channel analysis. These methods can be applied to GAFCHROMIC EBT3 film dosimetry for radiation field analysis and verification of IMRT plans. METHODS: A single-film exposure was used to achieve dose calibration, and the accuracy was verified based on comparisons with the square-field calibration method...
2017: PloS One
https://www.readbyqxmd.com/read/28749373/dosimetric-evaluation-of-a-commercial-proton-spot-scanning-monte-carlo-dose-algorithm-comparisons-against-measurements-and-simulations
#15
Jatinder Saini, Dominic Maes, Alexander Egan, Stephen R Bowen, Sara St James, Martin Janson, Tony Wong, Charles Bloch
RaySearch Americas Inc. (NY) has introduced a commercial Monte Carlo dose algorithm (RS-MC) for routine clinical use in proton spot scanning. In this report, we provide a validation of this algorithm against phantom measurements and simulations in GATE/GEANT4 software package. We also compared the performance of RayStation analytical algorithm (RS-PBA) against the RS-MC algorithm. Methods: A beam model (G-MC) for spot scanning gantry at our proton center was implemented in the GATE software package. The model was validated against measurements in a water phantom and was used for benchmarking the RS-MC...
July 27, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28741892/dose-comparison-between-gafchromic-film-xio-and-monaco-treatment-planning-systems-in-a-novel-pelvic-phantom-that-contains-a-titanium-hip-prosthesis
#16
Nicholas Ade, F C P du Plessis
The presence of metallic prostheses during external beam radiotherapy of malignancies in the pelvic region has the potential to strongly influence the dose distribution to the target and to tissue surrounded by the prostheses. This study systematically investigates the perturbation effects of unilateral titanium prosthesis on 6 and 15 MV photon beam dose distributions using Gafchromic EBT2 film measurements in a novel pelvic phantom made out of a stack of nylon slices. Comparisons were also made between the film data and dose calculations made on XiO and Monaco treatment planning systems...
July 25, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28739211/investigating-the-surface-dose-contribution-of-intrafractional-kv-imaging-in-cyberknife-based-stereotactic-radiosurgery
#17
Abdulmecit Canbolat, Faruk Zorlu, Pervin Hurmuz, Mete Yeginer, Gokhan Ozyigit
CyberKnife treatment consists of hundreds of noncoplanar beams and numerous intrafractional images that can be taken during a single treatment fraction; thus, doses because of imaging should be considered in this technique. The aim of this study is to investigate the in-field and out-of-field surface doses induced from kV imaging system during stereotactic radiosurgery (SRS) treatment. The imaging-induced surface doses were measured at the center of the imaging field and within ±15-cm distance from the center in both craniocaudal and lateral directions...
July 21, 2017: Medical Dosimetry: Official Journal of the American Association of Medical Dosimetrists
https://www.readbyqxmd.com/read/28730652/effects-of-collimator-angle-couch-angle-and-starting-phase-on-motion-tracking-dynamic-conformal-arc-therapy-4d-dcat
#18
Zhengzheng Xu, Rutao Yao, Matthew B Podgorsak, Iris Z Wang
PURPOSE: The aim of this study was to find an optimized configuration of collimator angle, couch angle, and starting tracking phase to improve the delivery performance in terms of MLC position errors, maximal MLC leaf speed, and total beam-on time of DCAT plans with motion tracking (4D DCAT). METHOD AND MATERIALS: Nontracking conformal arc plans were first created based on a single phase (maximal exhalation phase) of a respiratory motion phantom with a spherical target...
July 21, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28719019/initial-testing-of-a-pixelated-silicon-detector-prototype-in-proton-therapy
#19
Andrew J Wroe, Grant McAuley, Anthony V Teran, Jeannie Wong, Marco Petasecca, Michael Lerch, James M Slater, Anatoly B Rozenfeld
As technology continues to develop, external beam radiation therapy is being employed, with increased conformity, to treat smaller targets. As this occurs, the dosimetry methods and tools employed to quantify these fields for treatment also have to evolve to provide increased spatial resolution. The team at the University of Wollongong has developed a pixelated silicon detector prototype known as the dose magnifying glass (DMG) for real-time small-field metrology. This device has been tested in photon fields and IMRT...
July 18, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28714067/technical-note-evaluation-of-plastic-scintillator-detector-for-small-field-stereotactic-patient-specific-quality-assurance
#20
Yujiao Qin, Stephen J Gardner, Joshua Kim, Yimei Huang, Ning Wen, Anthony Doemer, Indrin J Chetty
PURPOSE: To evaluate the performance of a commercial plastic scintillator detector (PSD) for small-field stereotactic patient-specific quality assurance (QA) measurements using flattening-filter-free beam. METHODS: A total of 10 spherical targets [volume range: (0.03 cc-2 cc)] were planned with two techniques: (a) dynamic conformal arc (DCA-10 plans) and (b) volumetric modulated arc therapy (VMAT-10 plans). All plans were generated using Varian Eclipse treatment planning system, and AcurosXB v...
October 2017: Medical Physics
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