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https://www.readbyqxmd.com/read/28749373/dosimetric-evaluation-of-a-commercial-proton-spot-scanning-monte-carlo-dose-algorithm-comparisons-against-measurements-and-simulations
#1
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
#2
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
#3
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
#4
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
#5
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
#6
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
#7
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
#8
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
#9
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
#10
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
#11
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
#12
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
https://www.readbyqxmd.com/read/28610693/assessment-of-peak-skin-dose-in-interventional-cardiology-a-comparison-between-gafchromic-film-and-dosimetric-software-em-dose
#13
J Greffier, C Van Ngoc Ty, G Bonniaud, G Moliner, B Ledermann, L Schmutz, L Cornillet, G Cayla, J P Beregi, F Pereira
OBJECTIVE: To compare the use of a dose mapping software to Gafchromic film measurement for a simplified peak skin dose (PSD) estimation in interventional cardiology procedure. METHODS: The study was conducted on a total of 40 cardiac procedures (20 complex coronary angioplasty of chronic total occlusion (CTO) and 20 coronary angiography and coronary angioplasty (CA-PTCA)) conducted between January 2014 to December 2015. PSD measurement (PSDFilm) was obtained by placing XR-RV3 Gafchromic under the patient's back for each procedure...
June 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28607652/simulation-of-therapeutic-electron-beam-tracking-through-a-non-uniform-magnetic-field-using-finite-element-method
#14
Mohammad Javad Tahmasebibirgani, Reza Maskani, Mohammad Ali Behrooz, Mansour Zabihzadeh, Hojatollah Shahbazian, Jafar Fatahiasl, Nahid Chegeni
INTRODUCTION: In radiotherapy, megaelectron volt (MeV) electrons are employed for treatment of superficial cancers. Magnetic fields can be used for deflection and deformation of the electron flow. A magnetic field is composed of non-uniform permanent magnets. The primary electrons are not mono-energetic and completely parallel. Calculation of electron beam deflection requires using complex mathematical methods. In this study, a device was made to apply a magnetic field to an electron beam and the path of electrons was simulated in the magnetic field using finite element method...
April 2017: Electronic Physician
https://www.readbyqxmd.com/read/28527605/analysis-of-gafchromic-ebt3-film-calibration-irradiated-with-gamma-rays-from-different-systems-gamma-knife-and-cobalt-60-unit
#15
Monsen Najafi, Ghazale Geraily, Alireza Shirazi, Mahbod Esfahani, Javad Teimouri
In recent years, Gafchromic films are used as an advanced instrument for dosimetry systems. The EBT3 films are a new generation of Gafchromic films. Our main interest is to compare the response of the EBT3 films exposed to gamma rays provided by the Theratron 780C as a conventional radiotherapy system and the Leksell Gamma Knife as a stereotactic radiotherapy system (SRS). Both systems use Cobalt-60 sources, thus using the same energy. However, other factors such as source-to-axis distance, number of sources, dose rate, direction of irradiation, shape of phantom, the field shape of radiation, and different scatter contribution may influence the calibration curve...
May 17, 2017: Medical Dosimetry: Official Journal of the American Association of Medical Dosimetrists
https://www.readbyqxmd.com/read/28513854/verification-of-dose-profiles-generated-by-the-convolution-algorithm-of-the-gamma-knife-%C3%A2-radiosurgery-planning-system
#16
Hyun-Tai Chung, Jeong-Hoon Park, Kook Jin Chun
PURPOSE: A convolution algorithm that takes into account electron-density inhomogeneity was recently introduced to calculate dose distributions for the Gamma Knife (GK) Perfexion(™) treatment planning program. The accuracies of the dose distributions computed using the convolution method were assessed using an anthropomorphic phantom and film dosimetry. METHODS: Absorbed-dose distributions inside a phantom (CIRS Radiosurgery Head Phantom, Model 605) were calculated using the convolution method of the GK treatment-planning software (Leksell Gamma Plan(®) version 10...
May 17, 2017: Medical Physics
https://www.readbyqxmd.com/read/28479873/comparison-of-surface-dose-delivered-by-7%C3%A2-mv-unflattened-and-6%C3%A2-mv-flattened-photon-beams
#17
Ashokkumar Sigamani, Arunai Nambiraj
AIM: The purpose of this study is to determine the central-axis dose in the buildup region and the surface dose delivered by a 6 MV flattened photon beam (6 MV-FB) and a higher energy unflattened (7 MV-FFF) therapeutic photon beam for different-sized square fields with open fields and modifying filters. MATERIALS AND METHODS: The beams are produced by a Siemens Artiste linear accelerator with a NACP-02 ionization chamber and the dose is measured by using GafChromic film and two different, commonly used, dosimeters: a p-type photon semiconductor dosimeter (PFD) and a cylindrical ionization chamber (CC13)...
May 2017: Reports of Practical Oncology and Radiotherapy
https://www.readbyqxmd.com/read/28470819/tuning-of-acurosxb-source-size-setting-for-small-intracranial-targets
#18
Stephen J Gardner, Siming Lu, Chang Liu, Ning Wen, Indrin J Chetty
This study details a method to evaluate the source size selection for small field intracranial stereotactic radiosurgery (SRS) deliveries in Eclipse treatment planning system (TPS) for AcurosXB dose calculation algorithm. Our method uses end-to-end dosimetric data to evaluate a total of five source size selections (0.50 mm, 0.75 mm, 1.00 mm, 1.25 mm, and 1.50 mm). The dosimetric leaf gap (DLG) was varied in this analysis (three DLG values were tested for each scenario). We also tested two MLC leaf designs (standard and high-definition MLC) and two delivery types for intracranial SRS (volumetric modulated arc therapy [VMAT] and dynamic conformal arc [DCA])...
May 4, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28464743/monte-carlo-simulations-of-a-low-energy-proton-beamline-for-radiobiological-experiments
#19
Tordis J Dahle, Anne Marit Rykkelid, Camilla H Stokkevåg, Andrea Mairani, Andreas Görgen, Nina J Edin, Eivind Rørvik, Lars Fredrik Fjæra, Eirik Malinen, Kristian S Ytre-Hauge
BACKGROUND: In order to determine the relative biological effectiveness (RBE) of protons with high accuracy, radiobiological experiments with detailed knowledge of the linear energy transfer (LET) are needed. Cell survival data from high LET protons are sparse and experiments with low energy protons to achieve high LET values are therefore required. The aim of this study was to quantify LET distributions from a low energy proton beam by using Monte Carlo (MC) simulations, and to further compare to a proton beam representing a typical minimum energy available at clinical facilities...
June 2017: Acta Oncologica
https://www.readbyqxmd.com/read/28457741/commissioning-of-applicator-guided-stereotactic-body-radiation-therapy-boost-with-high-dose-rate-brachytherapy-for-advanced-cervical-cancer-using-radiochromic-film-dosimetry
#20
Saad Aldelaijan, Shada Wadi-Ramahi, Ahmad Nobah, Belal Moftah, Slobodan Devic, Noha Jastaniyah
PURPOSE: To describe an EBT3 GAFCHROMIC film-based dosimetry method to be used in commissioning of a combined HDR brachytherapy (HDRB) and stereotactic body radiation therapy (SBRT) boost for treatment of advanced cervical cancer involving extensive residual disease after external beam treatment. METHODS AND MATERIALS: A cube phantom was designed to firmly fit an intrauterine tandem applicator and EBT3 radiochromic film pieces. A high-risk clinical target volume (CTVHR, Total) was contoured with an extended arm at one side...
April 27, 2017: Brachytherapy
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