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radiation dosimetry

Celina Yang, Kyle Bromma, Wonmo Sung, Jan Schuemann, Devika Chithrani
Combined use of chemotherapy and radiation therapy is commonly used in cancer treatment, but the toxic effects on normal tissue are a major limitation. This study assesses the potential to improve radiation therapy when combining gold nanoparticle (GNP) mediated radiation sensitization with chemoradiation compared to chemoradiation alone. Incorporation of GNPs with 2 Gy, 6 MV (megavoltage) radiation resulted in a 19 ± 6% decrease in survival of MDA-MB-231 cells. Monte-Carlo simulations were performed to assess dosimetric differences in the presence of GNPs in radiation...
May 22, 2018: Cancers
C Robert, I Dumas, F Martinetti, C Chargari, C Haie-Meder, D Lefkopoulos
Since 1995, the brachytherapy dosimetry protocols follow the methodology recommended by the Task Group 43. This methodology, which has the advantage of being fast, is based on several approximations that are not always valid in clinical conditions. Model-based dose calculation algorithms have recently emerged in treatment planning stations and are considered as a major evolution by allowing for consideration of the patient's finite dimensions, tissue heterogeneities and the presence of high atomic number materials in applicators...
May 18, 2018: Cancer Radiothérapie: Journal de la Société Française de Radiothérapie Oncologique
Alexandra Zvereva, Florian Kamp, Helmut Schlattl, Maria Zankl, Katia Parodi
PURPOSE: Variance-based sensitivity analysis (SA) is described and applied to the radiation dosimetry model proposed by the Committee on Medical Internal Radiation Dose (MIRD) for the organ-level absorbed dose calculations in nuclear medicine. The uncertainties in the dose coefficients thus calculated are also evaluated. METHODS: A Monte Carlo approach was used to compute first-order and total-effect SA indices, which rank the input factors according to their influence on the uncertainty in the output organ doses...
May 17, 2018: Medical Physics
Olivia A García-Garduño, Manuel A Rodríguez-Ávila, José M Lárraga-Gutiérrez
Silicon-diode-based detectors are commonly used for the dosimetry of small radiotherapy beams due to their relatively small volumes and high sensitivity to ionizing radiation. Nevertheless, silicon-diode-based detectors tend to over-respond in small fields because of their high density relative to water. For that reason, detector-specific beam correction factors ([Formula: see text]) have been recommended not only to correct the total scatter factors but also to correct the tissue maximum and off-axis ratios...
2018: PloS One
Stuart Greenham, Stephen Manley, Kirsty Turnbull, Matthew Hoffmann, Amara Fonseca, Justin Westhuyzen, Andrew Last, Noel J Aherne, Thomas P Shakespeare
Aim: To develop and apply a clinical incident taxonomy for radiation therapy. Background: Capturing clinical incident information that focuses on near-miss events is critical for achieving higher levels of safety and reliability. Methods and materials: A clinical incident taxonomy for radiation therapy was established; coding categories were prescription, consent, simulation, voluming, dosimetry, treatment, bolus, shielding, imaging, quality assurance and coordination of care...
May 2018: Reports of Practical Oncology and Radiotherapy
Naoki Kinoshita, Hiroshi Oguchi, Toshiki Adachi, Hiroki Shioura, Hirohiko Kimura
Background: Uncertainty in the calibration of high-energy radiation sources is dependent on user and equipment type. Aim: We evaluated the uncertainty in the positioning of a cylindrical chamber at a reference depth for reference dosimetry of high-energy photon beams and the resulting uncertainty in the chamber readings for 6- and 10-MV photon beams. The aim was to investigate major contributions to the positioning uncertainty to reduce the uncertainty in calibration for external photon beam radiotherapy...
May 2018: Reports of Practical Oncology and Radiotherapy
Críssia Carem Paiva Fontainha, Neriene Alves, Wilmar Barbosa Ferraz, Luiz Oliveira de Faria
New materials have been widely investigated for ionizing radiation dosimetry for medical procedures. Carbon-doped alumina (α-Al2 O3 :C) have been reported to be excellent thermoluminescent (TL) and optically stimulated luminescence (OSL) radiation dosimeters. In the present study, we have synthetized nano and micro-sized α-Al2 O3 :C polycrystals, doped with different percentages of carbon atoms aiming to compare their efficiency as TL dosimeters. The dosimetric characteristics for X ray and gamma fields were investigated...
May 7, 2018: Applied Radiation and Isotopes
Warren R Bacorro, Ryan Anthony F Agas, Stellar Marie R Cabrera, Maureen R Bojador, Paolo G Sogono, Michael Benedict A Mejia, Teresa T Sy Ortin
PURPOSE: In nasopharyngeal cancer, brachytherapy is given as boost in primary treatment or as salvage for recurrent or persistent disease. The Rotterdam nasopharyngeal applicator (RNA) allows for suboptimal reduction of soft palate radiation dose, based on image-guided brachytherapy plans. Building on the RNA, we propose a novel design, the Benavides nasopharyngeal applicator (BNA). METHODS AND MATERIALS: The virtual BNA was reconstructed on two cases (one T1, one T2) previously treated with intracavitary brachytherapy using the RNA...
May 11, 2018: Brachytherapy
Cheng B Saw, SiCong Li, Frank Battin, Janice McKeague, Christopher A Peters
Eclipse is a 3-dimensional (3D) treatment planning system for radiation therapy offered by Varian Medical Systems, Inc. The system has the network connectivity for the electronic transfer of image datasets and digital data communication among different equipment. The scope of this project for this special issue of Medical Dosimetry on 3D treatment planning systems is the assessment of planning tools in the external beam planning module of Eclipse to generate optimized treatment plans for patients undergoing external beam radiation therapy...
July 2018: Medical Dosimetry: Official Journal of the American Association of Medical Dosimetrists
Yong Hum Na, Yi-Fang Wang, Paul J Black, Christian Velten, Xin Qian, Shih-Chi Lin, John Adamovics, Cheng-Shie Wuu
PURPOSE: The precise dosimetric and geometric characteristics of small animal irradiators are essential to achieving reproducible dose delivery, especially in cases where image-guidance is utilized. Currently, radiochromic film is the established measurement tool used to evaluate beam characteristics for these systems. However, only 2D information can be acquired with film. This study characterized both the dosimetric and geometric properties of the small animal research radiation platform (SARRP, Xstrahl) for commissioning purposes using a 3D radiochromic dosimetry system with a sub-millimeter resolution optical computed tomography (OCT) scanner...
May 10, 2018: Medical Physics
Gérard Lagmago Kamta
The Canadian Organization of Medical Physicists (COMP), in close partnership with the Canadian Partnership for Quality Radiotherapy (CPQR) has developed a series of Technical Quality Control (TQC) guidelines for radiation treatment equipment. These guidelines outline the performance objectives that equipment should meet to ensure an acceptable level of radiation treatment quality. The TQC guidelines have been rigorously reviewed and field tested in a variety of Canadian radiation treatment facilities. The development process enables rapid review and update to keep the guidelines current with changes in technology (the most update version of this guideline can be found on the CPQR website)...
May 9, 2018: Journal of Applied Clinical Medical Physics
Faiçal A A Slimani, Mahdjoub Hamdi, M'hamed Bentourkia
Monte Carlo (MC) simulation is widely recognized as an important technique to study the physics of particle interactions in nuclear medicine and radiation therapy. There are different codes dedicated to dosimetry applications and widely used today in research or in clinical application, such as MCNP, EGSnrc and Geant4. However, such codes made the physics easier but the programming remains a tedious task even for physicists familiar with computer programming. In this paper we report the development of a new interface GEANT4 Dose And Radiation Interactions (G4DARI) based on GEANT4 for absorbed dose calculation and for particle tracking in humans, small animals and complex phantoms...
May 1, 2018: Computerized Medical Imaging and Graphics: the Official Journal of the Computerized Medical Imaging Society
Fatima M Jadu, Asmaa A Alzahrani, Maha A Almutairi, Salma O Al-Amoudi, Ahmed M Jan, Mawya A Khafaji
To investigate changes in the effective radiation dose (E) in relation to variations in voxel (VOX) size settings and the field-of-view (FOV) centralization. Methods: This cross-sectional dosimetry study used nanoDot OSLD dosimeters placed at 25 pre-determined sites in the head and neck slices of a RANDO male phantom to measure the absorbed radiation. The imaging scans took place at King Abdulaziz University Dental Hospital, Jeddah, Saudi Arabia between September 2016 and May 2017 using the i-CAT classic cone beam computed tomography (CBCT)  unit...
May 2018: Saudi Medical Journal
M Robatjazi, S R Mahdavi, H R Baghani, H R Mirzaei, M Mousavi, N Nafissi, E Akbari
Background: One of the main problems of dedicated IORT accelerators is to determine dosimetric characteristics of the electron beams. Monte Carlo simulation of IORT accelerator head and produced beam will be useful to improve the accuracy of beam dosimetry. Materials and Methods: Liac accelerator head was modeled using the BEAMnrcMonte Carlo simulation system. Phase-space files were generated at the bottom of the applicators. These phase-space files were used as an input source in DOSXYZnrc and BEAMDP codes for dose calculation and analysis of the characteristic of the electron beams in all applicators and energies...
March 2018: Journal of Biomedical Physics & Engineering
Gary D Lewis, Jennifer E Agrusa, Bin S Teh, Maria M Gramatges, Viral Kothari, Carl E Allen, Arnold C Paulino
PURPOSE: The purpose of this study is to determine the incidence of radiation pneumonitis (RP) in children receiving radiation therapy (RT) for Hodgkin lymphoma (HL). METHODS AND PATIENTS: A retrospective chart review was conducted of pediatric HL patients who received multiagent chemotherapy followed by RT to any part of the chest. The National Cancer Institute Common Terminology Criteria for Adverse Events, version 4.03, was used to determine the RP grade. Parameters analyzed included sex; age; bleomycin dose; and RT dosimetric variables such as mean lung dose (MLD), mean individual (i; right vs left) lung dose or iMLD, V5 to V25, and individual lung V5 to V25...
February 4, 2018: Practical Radiation Oncology
Jierui Zou, Junwang Guo, Guofu Dong, Lei Ma, Jianbo Cong, Ye Liu, Ye Tian, Ke Wu
The X-band in vivo EPR tooth dosimetry is promising as a tool for the initial triage after a large-scale radiation accident. The dielectric losses caused by water on the tooth surface (WTS) are one of the major sources of inaccuracies in this method. The effect was studied by theoretical simulation calculations and experiments with water films of various thicknesses on teeth. The results demonstrate the possibility of sufficiently accurate measurements of the radiation-induced signal of the tooth enamel provided that the thickness of the water film on the tooth is below 60 µm...
April 24, 2018: Applied Radiation and Isotopes
Tereza Hanušová, Kamila Johnová, Matěj Navrátil, Jiří Valenta, Lutz Müller
Activation of detectors and phantoms used for commissioning and quality assurance of clinical proton beams may lead to radiation protection issues. Good understanding of the activation nuclide vectors involved is necessary to assess radiation risk for the personnel working with these devices on a daily basis or to fulfill legal requirements regarding transport of radioactive material and its release to the public. Eleven devices and material samples were irradiated with a 220 MeV proton pencil beam (PBS, Proton Therapy Center, Prague)...
May 4, 2018: Physics in Medicine and Biology
Stefan Dorsch, Philipp Mann, Clemens Lang, Peter Häring, Armin Runz, Christian P Karger
For conventional irradiation devices, the radiation isocenter accuracy is determined by star shot measurements on films. In magnetic resonance (MR)-guided radiotherapy devices, the results of this test may be altered by the magnetic field and the need to align radiation and imaging isocenter may require a modification of measurement procedures. Polymer dosimetry gels (PG) may offer a way to perform both, radiation and imaging isocenter test, however, it has to be shown first that PG reveals comparable results as the conventionally applied films...
May 3, 2018: Physics in Medicine and Biology
Michael G Stabin, Jeffry A Siegel, X George Xu
No abstract text is available yet for this article.
May 2018: Journal of Nuclear Medicine: Official Publication, Society of Nuclear Medicine
Abdulaziz Alhazmi, Chiara Gianoli, Sebastian Neppl, Juliana Martins, Stella Veloza, Mark Podesta, Frank Verhaegen, Michael Reiner, Claus Belka, Katia Parodi
Intensity Modulated Radiation Therapy (IMRT) and Volumetric Modulated Arc Therapy (VMAT) are relatively complex treatment delivery techniques and require Quality Assurance (QA) procedures. Pre-treatment dosimetric verification represents a fundamental QA rocedure in daily clinical routine in radiation therapy. The purpose of this study is to develop an EPID-based approach to reconstruct a 3D dose distribution as imparted to a virtual cylindrical water phantom to be used for plan-specific pre-treatment dosimetric verification for IMRT and VMAT plans...
May 1, 2018: Physics in Medicine and Biology
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