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radiation dosimetry

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https://www.readbyqxmd.com/read/28102956/experimental-verification-of-4d-monte-carlo-simulations-of-dose-delivery-to-a-moving-anatomy
#1
Sara Gholampourkashi, Miro Vujicic, Jason Belec, Joanna E Cygler, Emily Heath
PURPOSE: To evaluate a novel 4D Monte Carlo simulation tool by comparing calculations to physical measurements using a respiratory motion phantom. METHODS: We used a dynamic Quasar phantom in both stationary and breathing states (sinusoidal motion of amplitude of 1.8 cm and period of 3.3 s) for dose measurements on an Elekta Agility linear accelerator. Gafchromic EBT3 film and the RADPOS 4D dosimetry system were placed inside the lung insert of the phantom to measure dose profiles and point-dose values at the center of the spherical tumor inside the insert...
January 2017: Medical Physics
https://www.readbyqxmd.com/read/28102953/air-kerma-strength-determination-of-an-hdr-192-ir-source-including-a-geometric-sensitivity-study-of-the-seven-distance-method
#2
Blake R Smith, John A Micka, Manik Aima, Larry A DeWerd, Wesley S Culberson
PURPOSE: To perform an in-air air-kerma strength (SK) calibration of the Bebig model Ir2.A85-2 192Ir high-dose rate (HDR) brachytherapy source manufactured by Mallinckrodt Medical (Westerduinweg, Germany) with the NIST-traceable seven-distance technique established by the University of Wisconsin. A comparison was made between the reference air-kerma rate (RAKR) reported on a certificate from the Physikalisch-Technische Bundesanstalt (Berlin, Germany) (PTB) primary laboratory and the SK determined at the University of Wisconsin Madison Radiation Research Center (UWMRRC)...
January 2017: Medical Physics
https://www.readbyqxmd.com/read/28102948/use-of-parallel-plate-ionization-chambers-in-reference-dosimetry-of-novac-and-liac-%C3%A2-mobile-electron-linear-accelerators-for-intraoperative-radiotherapy-a-multi-center-survey
#3
Paolo Scalchi, Alessia Ciccotelli, Giuseppe Felici, Assunta Petrucci, Raffaella Massafra, Valeria Piazzi, Paola D'Avenia, Francesca Cavagnetto, Federica Cattani, Raffaella Romagnoli, Antonella Soriani
PURPOSE: LIAC(®) and NOVAC are two mobile linear accelerators dedicated to intraoperative radiation therapy (IORT), generating electron beams in the energy range of 3-12 MeV. Due to high dose-per-pulse (up to 70 mGy per pulse), in 2003 the Italian National Institute of Health (ISS) stated that "for the measure of dose to water in reference conditions, ionization chambers cannot be employed and no published dosimetry protocol can be used". As a consequence, ferrous sulphate (or, alternatively alanine) dosimetry was recommended...
January 2017: Medical Physics
https://www.readbyqxmd.com/read/28102946/a-portal-dosimetry-dose-prediction-method-based-on-collapsed-cone-algorithm-using-the-clinical-beam-model
#4
J Martínez Ortega, N Gómez González, P Castro Tejero, M Pinto Monedero, N B Tolani, L Núñez Martín, R Sánchez Montero
PURPOSE: Amorphous silicon electronical portal imaging devices (EPIDs) are widely used for dosimetric measurements in Radiation Therapy. The purpose of this work was to determine if a portal dose prediction method can be utilized for dose map calculations based on the linear accelerator model within a commercial treatment planning system (Pinnacle(3) v8.0 m). METHODS: The method was developed for a 6 MV photon beam on the Varian Clinac 21-EX, at a nominal dose rate of 400 MU/min...
January 2017: Medical Physics
https://www.readbyqxmd.com/read/28094138/new-normoxic-n-hydroxymethyl-acrylamide-based-polymer-gel-for-3d-dosimetry-in-radiation-therapy
#5
Khalid A Rabaeh, Ahmed A Basfar, Akram A Almousa, Slobodan Devic, Belal Moftah
A novel composition of normoxic polymer gel dosimeters based on radiation-induced polymerization of N-(Hydroxymethyl)acrylamide (NHMA) is introduced in this study for 3D dosimetry for Quality Assurance (QA) in radiation therapy. Dosimeters were irradiated by 6, 10 and 18MV photon beams of a medical linear accelerator at various dose rates to doses of up to 20Gy. The dose response of polymer gel dosimeters was studied using nuclear magnetic resonance (NMR) spin-spin relaxation rate (R2) of hydrogen protons within the water molecule...
January 13, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28092407/study-of-potential-health-effects-of-electromagnetic-fields-of-telephony-and-wi-fi-using-chicken-embryo-development-as-animal-model
#6
Henri Woelders, Agnes de Wit, Alexander Lourens, Norbert Stockhofe, Bas Engel, Ina Hulsegge, Dirkjan Schokker, Paula van Heijningen, Stefan Vossen, Dave Bekers, Peter Zwamborn
The objective of this study is to investigate possible biological effects of radiofrequency electromagnetic fields (RF-EMF) as used in modern wireless telecommunication in a well-controlled experimental environment using chicken embryo development as animal model. Chicken eggs were incubated under continuous experimental exposure to GSM (1.8 GHz), DECT (1.88 GHz), UMTS (2.1 GHz), and WLAN (5.6 GHz) radiation, with the appropriate modulation protocol, using a homogeneous field distribution at a field strength of approximately 3 V/m, representing the maximum field level in a normal living environment...
January 16, 2017: Bioelectromagnetics
https://www.readbyqxmd.com/read/28089526/a-feasibility-study-of-2-mm-bolus-for-postmastectomy-radiation-therapy
#7
Lauren C Das, Daniel W Golden, Eugenia Perevalova, Anthony C Wong, Kimberly De Nardo, Christopher Stepaniak, Daniel S Joyce, Bradley P McCabe, Yasmin Hasan, Steven J Chmura, Anne McCall
PURPOSE: The purpose of this study was to prospectively evaluate the use of daily 2-mm bolus in patients undergoing postmastectomy radiation without reconstruction using optically stimulated luminescence dosimetry and weekly assessment of skin toxicity. METHODS AND MATERIALS: We prospectively collected data from the first 49 women treated with a daily 2-mm Superflab bolus during their postmastectomy radiation therapy from 2013 to 2016 at The University of Chicago Comprehensive Cancer Center at Silver Cross...
October 24, 2016: Practical Radiation Oncology
https://www.readbyqxmd.com/read/28089106/-edge-on-moskin-detector-for-stereotactic-beam-measurement-and-verification
#8
Wei Loong Jong, Ngie Min Ung, Ath Vannyat, Zulaikha Jamalludin, Anatoly Rosenfeld, Jeannie Hsiu Ding Wong
Dosimetry in small radiation field is challenging and complicated because of dose volume averaging and beam perturbations in a detector. We evaluated the suitability of the "Edge-on" MOSkin (MOSFET) detector in small radiation field measurement. We also tested the feasibility for dosimetric verification in stereotactic radiosurgery (SRS) and stereotactic radiotherapy (SRT). "Edge-on" MOSkin detector was calibrated and the reproducibility and linearity were determined. Lateral dose profiles and output factors were measured using the "Edge-on" MOSkin detector, ionization chamber, SRS diode and EBT2 film...
January 6, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28067253/whole-organ-and-islet-of-langerhans-dosimetry-for-calculation-of-absorbed-doses-resulting-from-imaging-with-radiolabeled-exendin
#9
Inge van der Kroon, Wietske Woliner-van der Weg, Maarten Brom, Lieke Joosten, Cathelijne Frielink, Mark W Konijnenberg, Eric P Visser, Martin Gotthardt
Radiolabeled exendin is used for non-invasive quantification of beta cells in the islets of Langerhans in vivo. High accumulation of radiolabeled exendin in the islets raised concerns about possible radiation-induced damage to these islets in man. In this work, islet absorbed doses resulting from exendin-imaging were calculated by combining whole organ dosimetry with small scale dosimetry for the islets. Our model contains the tissues with high accumulation of radiolabeled exendin: kidneys, pancreas and islets...
January 9, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28063356/nanoparticles-for-radiooncology-mission-vision-challenges
#10
REVIEW
Leoni A Kunz-Schughart, Anna Dubrovska, Claudia Peitzsch, Alexander Ewe, Achim Aigner, Samuel Schellenburg, Michael H Muders, Silke Hampel, Giuseppe Cirillo, Francesca Iemma, Rainer Tietze, Christoph Alexiou, Holger Stephan, Kristof Zarschler, Orazio Vittorio, Maria Kavallaris, Wolfgang J Parak, Lutz Mädler, Suman Pokhrel
Cancer is one of the leading non-communicable diseases with highest mortality rates worldwide. About half of all cancer patients receive radiation treatment in the course of their disease. However, treatment outcome and curative potential of radiotherapy is often impeded by genetically and/or environmentally driven mechanisms of tumor radioresistance and normal tissue radiotoxicity. While nanomedicine-based tools for imaging, dosimetry and treatment are potential keys to the improvement of therapeutic efficacy and reducing side effects, radiotherapy is an established technique to eradicate the tumor cells...
December 14, 2016: Biomaterials
https://www.readbyqxmd.com/read/28055251/commentary-opportunities-for-research-in-molecular-radiotherapy
#11
Glenn D Flux, Joe O'Sullivan, Mark N Gaze, Kevin M Prise
Cancer has been treated with radiopharmaceuticals for 80 years. A recent NCRI report from the Clinical and Translational Radiotherapy Research Working Group (CTRad) reviews the current status of molecular radiotherapy (MRT) and has highlighted the barriers to, and the opportunities for increased research activities. The report recommends a number of actions to promote this field, which in the dawning age of personalised medicine and theragnostics is of increasing importance, particularly with the clinical introduction of a range of new commercial radiotherapeutics at costs in line with those seen for conventional chemotherapeutics...
January 5, 2017: British Journal of Radiology
https://www.readbyqxmd.com/read/28048930/su-f-t-54-determination-of-the-aapm-tg-43-brachytherapy-dosimetry-parameters-for-a-new-titanium-encapsulated-yb-169-source-by-monte-carlo-calculations
#12
F Reynoso, J Munro, S Cho
PURPOSE: To determine the AAPM TG-43 brachytherapy dosimetry parameters of a new titanium-encapsulated Yb-169 source designed to maximize the dose enhancement during gold nanoparticle-aided radiation therapy (GNRT). METHODS: An existing Monte Carlo (MC) model of the titanium-encapsulated Yb-169 source, which was described in the current investigators' published MC optimization study, was modified based on the source manufacturer's detailed specifications, resulting in an accurate model of the titanium-encapsulated Yb-169 source that was actually manufactured...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048924/mo-b-brb-02-3d-dosimetry-in-the-clinic-imrt-technique-validation-in-sweden
#13
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/28048921/su-f-j-127-multi-institutional-evaluation-of-setup-organ-deformation-precision-dosimetry-in-total-marrow-irradiation
#14
D Zuro, S Hui
PURPOSE: Totals Marrow Irradiation (TMI) is a highly focused radiation delivery to the human skeleton structure therefore requiring a high amount of precision and accuracy for a quality treatment. Not much is known on how the patient position varies across multiple treatment fractions and how that positioning impacts the dose delivery. Currently TMI is studied as an international collaboration with multiple centers around the world; however, many of these centers used different pretreatment techniques...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048884/th-ef-204-02-small-field-radiation-therapy-physics-and-recent-recommendations-from-iaea-and-icru
#15
J Seuntjens
: Joanna E. Cygler, Jan Seuntjens, J. Daniel Bourland, M. Saiful Huq, Josep Puxeu Vaque, Daniel Zucca Aparicio, Tatiana Krylova, Yuri Kirpichev, Eric Ford, Caridad Borras Stereotactic Radiation Therapy (SRT) utilizes small static and dynamic (IMRT) fields, to successfully treat malignant and benign diseases using techniques such as Stereotactic Radiosurgery (SRS) and Stereotactic Body Radiation Therapy (SBRT). SRT is characterized by sharp dose gradients for individual fields and their resultant dose distributions...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048877/su-g-brb-08-investigation-on-the-magnetic-field-effect-on-tlds-oslds-and-gafchromic-films-using-an-mr-linac
#16
Z Wen, J Wang, W Jiang, D O'Brien, G Sawakuchi, G Ibbott
PURPOSE: To investigate whether a strong magnetic field (B=1.5 T) can affect dose responses of thermoluminescent dosimeters (TLDs), optically stimulated luminescence dosimeters (OSLDs) and Gafchromic films using an MR-Linac (Elekta) before and after the magnet was ramped down from 1.5 T to 0 T. METHODS: Three types of dosimeters (TLDs, OSLDs, EBT3 films) were divided into two groups. Group 1 was first irradiated in a phantom of Solid Water slabs (Standard Imaging) inside a B=1...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048872/we-fg-bra-10-radiodosimetry-of-a-novel-alpha-particle-therapy-targeted-to-uveal-melanoma-absorbed-dose-to-organs-in-mice
#17
Christopher J Tichacek, Narges K Tafreshi, Mikalai M Budzevich, Epifanio Ruiz, Thaddeus J Wadas, Mark L McLaughlin, Eduardo G Moros, David L Morse
PURPOSE: The melanocortin-1 receptor (MC1R) is expressed in 94% of uveal melanomas and is described as an ideal target for this untreatable disease. MC1RL is a high affinity MC1R specific peptidomimetic ligand that can serve as a scaffold for therapeutic conjugates such as alpha particle emitting isotopes. The purpose of this study was to assess normal tissue distribution and risk as a result of using the DOTA chelator conjugated to MC1RL to deliver (225) Ac: MC1RL-DOTA-(225) Ac. METHODS: 17 non-tumor bearing BALB/c mice were intravenously injected with the novel MC1RL-DOTA-(225) Ac radiopharmaceutical with an average initial administered activity of 2...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048847/su-f-t-21-a-novel-beam-light-view-collimating-applicator-for-hdr-ocular-conjunctiva-brachytherapy-treatments
#18
S Koren, J Kindler, A Guemnie Tafo, G Cohen, E Reich
PURPOSE: We propose the use of a HDR X-ray source collimator to apply a conformal, relatively small, radiation suitable for a single fraction with short delivery time. In addition, this technique can be applied using a radioactive source. METHODS: We have built a stainless steel 1.5 mm thick applicator, to accommodate the needle applicator of the Intra-Beam X-ray source. Additional cavity is created in the applicator to allow the hosting/nesting/positioning of a LED diode...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048755/mo-fg-campus-iep1-03-establishment-of-provincial-diagnostic-reference-levels-in-pediatric-imaging
#19
E Tonkopi, K O'Brien
PURPOSE: To establish provincial diagnostic reference levels (DRLs) in pediatric general radiography and computed tomography (CT) as a tool for the optimization of exposure parameters. METHODS: Patient dose survey was conducted in the only pediatric hospital in the province of Nova Scotia. The DRLs were established as the 75th percentile of patient dose distributions in different age groups. For routine radiography projections the DRLs were determined in terms of entrance surface dose (ESD) calculated from the radiation output measurements and the tube current-exposure time product (mAs) recorded for each examination...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048748/su-f-t-159-monte-carlo-simulation-studies-of-three-dimensional-dose-distribution-for-polymer-gel-dosimeter-and-radiochromic-gel-dosimeter-in-a-proton-beam
#20
M Park, G Kim, H Jung, S Park, S Park, Y Ji, J Yun
PURPOSE: The purpose of this simulation study is to evaluate the proton detectability of gel dosimeters, and estimate the three-dimensional dose distribution of protons in the radiochromic gel and polymer gel dosimeter compared with the dose distribution in water. METHODS: The commercial composition ratios of normoxic polymer gel and LCV micelle radiochromic gel were included in this simulation study. The densities of polymer and radiochromic gel were 1.024 and 1...
June 2016: Medical Physics
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