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Gafchromic film

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https://www.readbyqxmd.com/read/28930093/a-reusable-osl-film-for-2d-radiotherapy-dosimetry
#1
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-intra-oral-anterior-oblique-occlusal-views-a-risk-based-approach
#2
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 to 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 extra-thoracic 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...
September 11, 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
#3
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
#4
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...
August 18, 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
#5
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
#6
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
#7
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 isocentre...
August 4, 2017: Medical Physics
https://www.readbyqxmd.com/read/28750023/the-combination-of-the-error-correction-methods-of-gafchromic-ebt3-film
#8
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
#9
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
#10
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
#11
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
#12
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
#13
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/evaluation-of-plastic-scintillator-detector-for-small-field-stereotactic-patient-specific-quality-assurance
#14
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 ten spherical targets (volume range: [0.03cc-2cc]) were planned with two techniques: (1) Dynamic Conformal Arc (DCA-10 plans), and (2) Volumetric Modulated Arc Therapy (VMAT-10 plans). All plans were generated using Varian Eclipse treatment planning system, and AcurosXB v...
July 17, 2017: Medical Physics
https://www.readbyqxmd.com/read/28711188/plan-delivery-quality-assurance-for-cyberknife-statistical-process-control-analysis-of-350-film-based-patient-specific-qas
#15
J Bellec, N Delaby, F Jouyaux, M Perdrieux, J Bouvier, S Sorel, O Henry, C Lafond
PURPOSE: Robotic radiosurgery requires plan delivery quality assurance (DQA) but there has never been a published comprehensive analysis of a patient-specific DQA process in a clinic. We proposed to evaluate 350 consecutive film-based patient-specific DQAs using statistical process control. We evaluated the performance of the process to propose achievable tolerance criteria for DQA validation and we sought to identify suboptimal DQA using control charts. METHODS AND MATERIAL: DQAs were performed on a CyberKnife-M6 using Gafchromic-EBT3 films...
July 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28711185/dosimetric-characterization-of-3d-printed-bolus-at-different-infill-percentage-for-external-photon-beam-radiotherapy
#16
Rosalinda Ricotti, Delia Ciardo, Floriana Pansini, Alessia Bazani, Stefania Comi, Ruggero Spoto, Samuele Noris, Federica Cattani, Guido Baroni, Roberto Orecchia, Andrea Vavassori, Barbara Alicja Jereczek-Fossa
BACKGROUND AND PURPOSE: 3D printing is rapidly evolving and further assessment of materials and technique is required for clinical applications. We evaluated 3D printed boluses with acrylonitrile butadiene styrene (ABS) and polylactide (PLA) at different infill percentage. MATERIAL AND METHODS: A low-cost 3D printer was used. The influence of the air inclusion within the 3D printed boluses was assessed thoroughly both with treatment planning system (TPS) and with physical measurements...
July 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28706354/intensities-of-incident-and-transmitted-ultraviolet-a-rays-through-gafchromic-films
#17
Toshizo Katsuda, Rumi Gotanda, Tatsuhiro Gotanda, Takuya Akagawa, Nobuyoshi Tanki, Tadao Kuwano, Atsushi Noguchi, Kouichi Yabunaka
Gafchromic films have been applied to X-ray dosimetry in diagnostic radiology. To correct nonuniformity errors in Gafchromic films, X-rays in the double-exposure technique can be replaced with ultraviolet (UV)-A rays. Intensities of the incident and transmitted UV-A rays were measured. However, it is unclear whether the chemical color change of Gafchromic films affects the UV-A transmission intensity. Gafchromic EBT3 films were suitable to be used in this study because non-UV protection layers are present on both sides of the film...
April 2017: Journal of Medical Physics
https://www.readbyqxmd.com/read/28649154/skin-dose-mapping-for-non-uniform-x-ray-fields-using-a-backscatter-point-spread-function
#18
Sarath Vijayan, Zhenyu Xiong, Alok Shankar, Stephen Rudin, Daniel R Bednarek
Beam shaping devices like ROI attenuators and compensation filters modulate the intensity distribution of the x-ray beam incident on the patient. This results in a spatial variation of skin dose due to the variation of primary radiation and also a variation in backscattered radiation from the patient. To determine the backscatter component, backscatter point spread functions (PSF) are generated using EGS Monte-Carlo software. For this study, PSF's were determined by simulating a 1 mm beam incident on the lateral surface of an anthropomorphic head phantom and a 20 cm thick PMMA block phantom...
February 11, 2017: Proceedings of SPIE
https://www.readbyqxmd.com/read/28630887/calculation-of-the-entrance-skin-dose-distribution-for-fluoroscopically-guided-interventions-using-a-pencil-beam-backscatter-model
#19
Sarath Vijayan, Zhenyu Xiong, Stephen Rudin, Daniel R Bednarek
Radiation backscattered from the patient can contribute substantially to skin dose in fluoroscopically guided interventions (FGIs). The distribution of backscatter is not spatially uniform, and use of a single backscatter factor cannot provide an accurate determination of skin dose. This study evaluates a method to determine the backscatter spatial distribution through convolution of a backscatter-to-primary (BP) point spread function (PSFn). The PSFn is derived for a pencil beam using EGSnrc Monte Carlo software and is convolved with primary distributions using a dose-tracking system...
July 2017: Journal of Medical Imaging
https://www.readbyqxmd.com/read/28613197/experimental-and-simulation-analysis-of-radiation-of-the-beta-emitting-sources-in-a-magnetic-field
#20
Berrin Çavuşoğlu, Selda Sucu, Hatice Durak, Kadir Akgüngör, Hakan Epik, Türkan Ertay
OBJECTIVE: The behavior of beta particles under the magnetic field was investigated both theoretically and experimentally based on the assumption of reducing the damage to the normal tissues created by using magnetic field in radionuclide therapy. METHODS: A water-filled spherical medium and a beta particle source was formed by using Geant4 simulation software for the theoretical study. After applying a homogenous magnetic field, the volume of points at which the particles interact with the medium was calculated by determining particle range...
June 1, 2017: Molecular Imaging and Radionuclide Therapy
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