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Gafchromic film

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https://www.readbyqxmd.com/read/29764449/primo-software-as-a-tool-for-monte-carlo-simulations-of-intensity-modulated-radiotherapy-a-feasibility-study
#1
Alessandro Esposito, Sofia Silva, Jorge Oliveira, Joana Lencart, João Santos
BACKGROUND: IMRT provides higher dose conformation to the target and dose sparing to surrounding tissues than 3DCRT. Monte Carlo method in Medical Physics is not a novelty to approach dosimetric problems. A new PENELOPE based code named PRIMO recently was published. The most intriguing features of PRIMO are the user-friendly approach, the stand-alone property and the built-in definition of different linear accelerators models. Nevertheless, IMRT simulations are not yet implemented. METHODS: A Varian Trilogy with a Millennium120 MLC and a Varian Novalis with 120HD MLC were studied...
May 15, 2018: Radiation Oncology
https://www.readbyqxmd.com/read/29716332/spectral-calibration-of-ebt3-and-hd-v2-radiochromic-film-response-at-high-dose-using-20-mev-proton-beams
#2
Yiwei Feng, Henry F Tiedje, Katherine Gagnon, Robert Fedosejevs
Radiochromic film is used extensively in many medical, industrial, and scientific applications. In particular, the film is used in analysis of proton generation and in high intensity laser-plasma experiments where very high dose levels can be obtained. The present study reports calibration of the dose response of Gafchromic EBT3 and HD-V2 radiochromic films up to high exposure densities. A 2D scanning confocal densitometer system is employed to carry out accurate optical density measurements up to optical density 5 on the exposed films at the peak spectral absorption wavelengths...
April 2018: Review of Scientific Instruments
https://www.readbyqxmd.com/read/29704440/development-and-implementation-of-epid-based-quality-assurance-tests-for-the-small-animal-radiation-research-platform-sarrp
#3
Akbar Anvari, Yannick Poirier, Amit Sawant
PURPOSE: Although small animal image-guided radiotherapy (SA-IGRT) systems are used increasingly in preclinical research, tools for performing routine quality assurance (QA) have not been optimized and are not readily available. Robust, efficient, and reliable QA tools are needed to ensure the accuracy and reproducibility of SA-IGRT systems. Several investigators have reported custom-made phantoms and protocols for SA-IGRT systems QA. These are typically time and resource intensive and are therefore not well suited to the preclinical radiotherapy environment, in which physics support is limited and routine QA is performed by technical staff...
April 28, 2018: Medical Physics
https://www.readbyqxmd.com/read/29699800/dosimetric-effects-of-bolus-and-lens-shielding-in-treating-ocular-lymphomas-with-low-energy-electrons
#4
Lori Young, Landon S Wootton, Alan M Kalet, Olga Gopan, Fei Yang, Samuel Day, Michael Banitt, Jay J Liao
Radiation therapy is an effective treatment for primary orbital lymphomas. Lens shielding with electrons can reduce the risk of high-grade cataracts in patients undergoing treatment for superficial tumors. This work evaluates the dosimetric effects of a suspended eye shield, placement of bolus, and varying electron energies. Film (GafChromic EBT3) dosimetry and relative output factors were measured for 6, 8, and 10 MeV electron energies. A customized 5-cm diameter circle electron orbital cutout was constructed for a 6 × 6-cm applicator with a suspended lens shield (8-mm diameter Cerrobend cylinder, 2...
April 23, 2018: Medical Dosimetry: Official Journal of the American Association of Medical Dosimetrists
https://www.readbyqxmd.com/read/29681774/high-accuracy-dosimetry-with-small-pieces-of-gafchromic-films
#5
Ryszard Dąbrowski, Izabela Drozdyk, Paweł Kukołowicz
Aim: To investigate the influence of several factors on the accuracy of dose measurements and feasibility of application of small Gafchromic detectors for postal audit. Background: Our experience showed that precision of dose measurements with small pieces of Gafchromic films may be significantly improved. Materials and methods: Gafchromic films with dimensions of 1 × 1, 2 × 2 and 3 × 3 cm2 were exposed to 6 MV X-rays at dose levels of 50 cGy-210 cGy...
March 2018: Reports of Practical Oncology and Radiotherapy
https://www.readbyqxmd.com/read/29665705/topogram-based-tube-current-modulation-of-head-computed-tomography-for-optimizing-image-quality-while-protecting-the-eye-lens-with-shielding
#6
Ming-Fang Lin, Chia-Yuen Chen, Yuan-Hao Lee, Chia-Wei Li, Leo E Gerweck, Hao Wang, Wing P Chan
Background Multiple rounds of head computed tomography (CT) scans increase the risk of radiation-induced lens opacification. Purpose To investigate the effects of CT eye shielding and topogram-based tube current modulation (TCM) on the radiation dose received by the lens and the image quality of nasal and periorbital imaging. Material and Methods An anthropomorphic phantom was CT-scanned using either automatic tube current modulation or a fixed tube current. The lens radiation dose was estimated using cropped Gafchromic films irradiated with or without a shield over the orbit...
January 1, 2018: Acta Radiologica
https://www.readbyqxmd.com/read/29626289/dosimetric-changes-with-computed-tomography-automatic-tube-current-modulation-techniques
#7
Sofia Spampinato, Anna Maria Gueli, Pietro Milone, Luigi Angelo Raffaele
The study is aimed at a verification of dose changes for a computed tomography automatic tube-current modulation (ATCM) technique. For this purpose, anthropomorphic phantom and Gafchromic® XR-QA2 films were used. Radiochromic films were cut according to the shape of two thorax regions. The ATCM algorithm is based on noise index (NI) and three exam protocols with different NI were chosen, of which one was a reference. Results were compared with dose values displayed by the console and with Poisson statistics...
April 6, 2018: Radiological Physics and Technology
https://www.readbyqxmd.com/read/29609815/monte-carlo-uncertainty-analysis-of-dose-estimates-in-radiochromic-film-dosimetry-with-single-channel-and-multichannel-algorithms
#8
Juan Antonio Vera-Sánchez, Carmen Ruiz-Morales, Antonio González-López
PURPOSE: To provide a multi-stage model to calculate uncertainty in radiochromic film dosimetry with Monte-Carlo techniques. This new approach is applied to single-channel and multichannel algorithms. MATERIAL AND METHODS: Two lots of Gafchromic EBT3 are exposed in two different Varian linacs. They are read with an EPSON V800 flatbed scanner. The Monte-Carlo techniques in uncertainty analysis provide a numerical representation of the probability density functions of the output magnitudes...
March 2018: Physica Medica: PM
https://www.readbyqxmd.com/read/29578579/intensity-modulated-operating-mode-of-the-rotating-gamma-system
#9
Bishwambhar Sengupta, Laszlo Gulyas, Donald Medlin, Tibor Koroknai, David Takacs, Gyorgy Filep, Peter Panko, Bence Godo, Tamas Hollo, Xiao Ran Zheng, Imre Fedorcsak, Jozsef Dobai, Laszlo Bognar, Endre Takacs
PURPOSE: The purpose of this work is to explore two novel operation modalities of the rotating gamma systems (RGS) that could expand its clinical application to lesions in close proximity to critical organs at risk (OAR). METHODS: The approach taken in this study consists of two components. First, a Geant4 based, Monte Carlo (MC) simulation toolkit is used to model the dosimetric properties of the RGS Vertex 360™ for the normal, intensity modulated radiosurgery (IMRS), and speed modulated radiosurgery (SMRS) operation modalities...
March 26, 2018: Medical Physics
https://www.readbyqxmd.com/read/29577330/technical-note-impact-of-region-of-interest-size-and-location-in-gafchromic-film-dosimetry
#10
Neda Gholizadeh Sendani, Alireza Karimian, Clara Ferreira, Parham Alaei
PURPOSE: To evaluate dependence of measured dose on size and location of region of interest (ROI) in Gafchromic EBT3 film dosimetry. METHODS: Gafchromic EBT3 films were irradiated perpendicularly using the 6MV beam from a linear accelerator at 10 cm depth (100 cm SSD) of a 30×30×20 cm3 solid water phantom for a range of field sizes of 6×6 to 100×100 mm2 . Image-J software was used for reading pieces of film. The appropriate location of ROIs in scanned films were found by two methods...
March 26, 2018: Medical Physics
https://www.readbyqxmd.com/read/29521280/beam-characterisation-of-the-1-5-t-mri-linac
#11
S J Woodings, J J Bluemink, J H W de Vries, Y Niatsetski, B van Veelen, J Schillings, J G M Kok, J W H Wolthaus, S L Hackett, B van Asselen, H M van Zijp, S Pencea, D A Roberts, J J W Lagendijk, B W Raaymakers
As a prerequisite for clinical treatments it was necessary to characterize the Elekta 1.5 T MRI-linac 7 MV FFF radiation beam. Following acceptance testing, beam characterization data were acquired with Semiflex 3D (PTW 31021), microDiamond (PTW 60019), and Farmer-type (PTW 30013 and IBA FC65-G) detectors in an Elekta 3D scanning water phantom and a PTW 1D water phantom. EBT3 Gafchromic film and ion chamber measurements in a buildup cap were also used. Special consideration was given to scan offsets, detector effective points of measurement and avoiding air gaps...
April 19, 2018: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/29519411/feasibility-of-setting-up-generic-alert-levels-for-maximum-skin-dose-in-fluoroscopically-guided-procedures
#12
Hannu Jarvinen, Jad Farah, Teemu Siiskonen, Olivera Ciraj-Bjelac, Jérémie Dabin, Eleftheria Carinou, Joanna Domienik-Andrzejewska, Dariusz Kluszczynski, Željka Knežević, Renata Kopec, Marija Majer, Francoise Malchair, Anna Negri, Piotr Pankowski, Sandra Sarmento, Annalisa Trianni
PURPOSE: The feasibility of setting-up generic, hospital-independent dose alert levels to initiate vigilance on possible skin injuries in interventional procedures was studied for three high-dose procedures (chemoembolization (TACE) of the liver, neuro-embolization (NE) and percutaneous coronary intervention (PCI)) in 9 European countries. METHODS: Gafchromic® films and thermoluminescent dosimeters (TLD) were used to determine the Maximum Skin Dose (MSD). Correlation of the online dose indicators (fluoroscopy time, kerma- or dose-area product (KAP or DAP) and cumulative air kerma at interventional reference point (Ka,r )) with MSD was evaluated and used to establish the alert levels corresponding to a MSD of 2 Gy and 5 Gy...
February 2018: Physica Medica: PM
https://www.readbyqxmd.com/read/29513647/ex-vivo-validation-of-a-stoichiometric-dual-energy-ct-proton-stopping-power-ratio-calibration
#13
Yunhe Xie, Christopher Ainsley, Lingshu Yin, Wei Zou, James McDonough, Timothy D Solberg, Alexander Lin, Boon-Keng Kevin Teo
A major source of uncertainty in proton therapy is the conversion of Hounsfield unit (HU) to proton stopping power ratio relative to water (SPR). In this study, we measured and quantified the accuracy of a stoichiometric dual energy CT (DECT) SPR calibration. We applied a stoichiometric DECT calibration method to derive the SPR using CT images acquired sequentially at [Formula: see text] and [Formula: see text]. The dual energy index was derived based on the HUs of the paired spectral images and used to calculate the effective atomic number (Z eff ), relative electron density ([Formula: see text]), and SPRs of phantom and biological materials...
March 7, 2018: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/29511500/-bax-bcl-2-expression-ratio-in-prediction-of-response-to-breast-cancer-radiotherapy
#14
Hosein Azimian, Mahdieh Dayyani, Mohammad Taghi Bahreyni Toossi, Mahmoud Mahmoudi
Objectives: Radiotherapy is one of the most effective modalities of cancer therapy, but clinical responses of individual patients varies considerably. To enhance treatment efficiency it is essential to implement an individual-based treatment. The aim of present study was to identify the mechanism of intrinsic apoptosis pathway on radiosensitivity and normal tissue complications caused by the radiotherapy. Materials and Methods: Peripheral blood mononuclear cells from ten breast cancer patients were exposed to 6MV X-rays to deliver 1 and 2 Gy...
March 2018: Iranian Journal of Basic Medical Sciences
https://www.readbyqxmd.com/read/29472093/image-quality-for-radiotherapy-ct-simulators-with-different-scanner-bore-size
#15
Nada Tomic, Pavlos Papaconstadopoulos, Saad Aldelaijan, Juha Rajala, Jan Seuntjens, Slobodan Devic
PURPOSE: We compare image quality parameters derived from phantom images taken on three commercially available radiotherapy CT simulators. To make an unbiased evaluation, we assured images were obtained with the same surface dose measured using XR-QA2 model GafChromic™ film placed at the imaging phantom surface for all three CT-simulators. METHODS: Radiotherapy CT simulators GE LS 16, Philips Brilliance Big Bore, and Toshiba Aquilion LB were compared in terms of spatial resolution, low contrast detectability, image uniformity, and contrast to noise ratio using CATPHAN-504 phantom, scanned with Head and Pelvis protocols...
January 2018: Physica Medica: PM
https://www.readbyqxmd.com/read/29434180/evaluation-of-a-small-animal-irradiation-system-for-animal-experiments-using-ebt3-model-gafchromic%C3%A2-film
#16
Yasuyuki Shimizu, Hiroaki Akasaka, Daisuke Miyawaki, Naritoshi Mukumoto, Masao Nakayama, Tianyuan Wang, Saki Osuga, Sachiko Inubushi, Ryuichi Yada, Yasuo Ejima, Kenji Yoshida, Takeaki Ishihara, Ryohei Sasaki
In cancer research, small animal models, for example, mice, rats, or rabbits, facilitate the in-depth study of biological processes and the effects of radiation treatment that can lead to breakthrough discoveries. However, the physical quality of small animal irradiation systems has not been previously evaluated. In this study, we evaluate the quality of a small animal irradiation system using GAFCHROMIC™ film and a Tough Water Phantom. The profiles and percentage depth dose curves for several irradiation conditions were measured to evaluate the quality of the irradiation system...
January 17, 2018: Kobe Journal of Medical Sciences
https://www.readbyqxmd.com/read/29431865/refinement-of-mlc-modeling-improves-commercial-qa-dosimetry-system-for-srs-and-sbrt-patient-specific-qa
#17
Yair Hillman, Josh Kim, Indrin Chetty, Ning Wen
PURPOSE: Mobius 3D (M3D) provides a volumetric dose verification of the treatment planning system's calculated dose using an independent beam model and a collapsed cone convolution superposition algorithm. However, there is a lack of investigation into M3D's accuracy and effectiveness for stereotactic radiosurgery (SRS) and stereotactic body radiotherapy (SBRT) quality assurance (QA). Here, we collaborated with the vendor to develop a revised M3D beam model for SRS/SBRT cases treated with a 6X flattening filter-free (FFF) beam and high-definition multiple leaf collimator (HDMLC) on an Edge linear accelerator...
April 2018: Medical Physics
https://www.readbyqxmd.com/read/29415148/experimental-evaluation-of-dosimetric-characterization-of-gafchromic-ebt3-and-ebt-xd-films-for-clinical-carbon-ion-beams
#18
Shunsuke Yonai, Chinatsu Arai, Kaoru Shimoyama, Nathalie Fournier-Bidoz
Radiochromic film is a very useful tool for 2D dosimetric measurements in radiotherapy because it is self-developing and has very high-spatial resolution. However, considerable care has to be taken in ion beam radiotherapy owing to the quenching effect of high-linear energy transfer (LET) radiation. In this study, the dose responses of GAFchromic EBT3 and EBT-XD films were experimentally investigated using the clinical carbon ion beam at the Heavy Ion Medical Accelerator in Chiba. Results showed that the relations between absorbed dose and net optical density could be expressed well using an equation proposed by Reinhardt (2015)...
February 3, 2018: Radiation Protection Dosimetry
https://www.readbyqxmd.com/read/29413856/abstract-id-230-experimental-and-monte-carlo-investigation-of-the-depth-dependent-fluence-perturbation-of-parallel-plate-chambers-in-clinical-electron-beams
#19
von Voigts-Rhetz Philip, Vorwerk Hilke, Zink Klemens
The electron fluence inside a parallel-plate ionization chamber positioned in a water phantom and exposed to a clinical electron beam deviates from the unperturbed fluence in water in absence of the chamber. One reason for the fluence perturbation is the "in-scattering effect" as described in ICRU 35. Aim of this work is a detailed experimental and with Monte Carlo simulations investigation of this effect. The experiments and Monte Carlo Simulations, with EGSnrc [1], were performed in a solid-water phantom (RW3) sized 30 × 30 × 30 cm3 ...
January 2018: Physica Medica: PM
https://www.readbyqxmd.com/read/29413837/measurement-of-activity-distribution-in-an-am-241-disc-source-using-peeled-off-gafchromic-ebt3-films
#20
Kwang-Ho Lee, Ji-Yong Shin, Eun-Hee Kim
Commercial alpha-emitting sources are fabricated mainly in a disc type. An alpha particle irradiator in Radiation Bioengineering Laboratory at Seoul National University was installed with an Am-241 disc source. Commercial Am-241 disc sources are fabricated by incorporating the radioactive element into a thin substrate layer. Those disc sources are utilized assuming that the radioactive element is uniformly distributed in the active layer of disc sources. In this study, we employed peeled-off Gafchromic EBT3 films to investigate the uniformity of areal radioactivity density over the disc source and to measure the effect of non-uniform activity distribution on dose distribution at the bottom of the cell culture dish positioned in a varying distance from the source...
May 2018: Applied Radiation and Isotopes
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