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Peter Homolka, Michael Figl, Andreas Wartak, Mathias Glanzer, Martina Duenkelmeyer, Azadeh Hojreh, Johann Hummel
An anthropomorphic head phantom including eye inserts allowing placement of TLDs 3 mm below the cornea has been produced on a 3D printer using photo-cured-acrylic resin to best allow tissue equivalence. Thus Hp(3) can be determined in radiological and interventional photon radiation fields. Eye doses and doses to the forehead have been compared to an Alderson RANDO head and a 3M Lucite skull phantom in terms of surface dose per incident air kerma for frontal irradiation since the commercial phantoms do not allow placement of TLDs 3 mm below the corneal surface...
February 13, 2017: Physics in Medicine and Biology
Marnie F Hazlehurst, Elizabeth W Spalt, Cynthia L Curl, Mark E Davey, Sverre Vedal, Gregory L Burke, Joel D Kaufman
Tools to assess time-location patterns related to environmental exposures have expanded from reliance on time-location diaries (TLDs) and questionnaires to use of geospatial location devices such as data-logging Global Positioning System (GPS) equipment. The Multi-Ethnic Study of Atherosclerosis and Air Pollution obtained typical time-location patterns via questionnaire for 6424 adults in six US cities. At a later time (mean 4.6 years after questionnaire), a subset (n=128) participated in high-resolution data collection for specific 2-week periods resulting in concurrent GPS and detailed TLD data, which were aggregated to estimate time spent in various microenvironments...
January 25, 2017: Journal of Exposure Science & Environmental Epidemiology
Mohmmadreza Aramesh, Kobra Aria Zanganeh, Masoud Dehdashtian, Arash Malekian, Jafar Fatahiasl
BACKGROUND: This study aimed to evaluate the radiation dose received by premature neonates using diagnostic radiographies. METHODS: This cross-sectional study was conducted on 116 premature neonates with gestational age from 25 to 37 weeks; with the diagnosis of neonatal respiratory distress syndrome (NRDS) and tachypnea, they were admitted to a neonatal intensive care unit (NICU) at Ahvaz Imam Khomeini Hospital in 2015. For assessing the dose received, the model GR-200 thermoluminescent dosimeter (TLD) was used...
February 2017: Journal of Clinical Medicine Research
L Di Maso, M Lawless, W Culberson, L DeWerd
PURPOSE: To characterize the energy dependence for TLD-100 microcubes in water at kilovoltage energies. METHODS: TLD-100 microcubes with dimensions of (1 × 1 × 1) mm(3) were irradiated with kilovoltage x-rays in a custom-built thin-window liquid water phantom. The TLD-100 microcubes were held in Virtual Water™ probes and aligned at a 2 cm depth in water. Irradiations were performed using the M-series x-ray beams of energies ranging from 50-250 kVp and normalized to a (60) Co beam located at the UWADCL...
June 2016: Medical Physics
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
Stephen Kry
: This presentation will highlight the upcoming TG-191 report: Clinical Use of Luminescent Dosimeters. Luminescent dosimetry based on TLD and OSLD is a practical, accurate, and precise technique for point dosimetry in medical physics applications. The charges of Task Group 191 were to detail the methodologies for practical and optimal luminescent dosimetry in a clinical setting. This includes (1) To review the variety of TLD/OSL materials available, including features and limitations of each...
June 2016: Medical Physics
M Aima, W Culberson, C Hammer, J Micka, L DeWerd
PURPOSE: The aim of this work is to determine the TG-43 dose-rate constant analog for a new directional low-dose rate brachytherapy source based on experimental methods and comparison to Monte Carlo simulations. The CivaSheet™ is a new commercially available planar source array comprised of a variable number of discrete directional source elements called "CivaDots". Given the directional nature and non-conventional design of the source, modifications to the AAPM TG-43 protocol for dosimetry are required...
June 2016: Medical Physics
N Viscariello, W Culberson, M Lawless, K Kunugi, L DeWerd
PURPOSE: Radiation biology research relies on an accurate radiation dose delivered to the biological target. Large field irradiations in a cabinet irradiator may use the AAPM TG-61 protocol. This relies on an air-kerma measurement and conversion to absorbed dose to water (Dw) on the surface of a water phantom using provided backscatter factors. Cell or small animal studies differ significantly from this reference geometry. This study aims to determine the impact of the lack of full scatter conditions in four representative geometries that may be used in radiobiology studies...
June 2016: Medical Physics
C Venencia, A Germanier, E Garrigo, P Castro Pena, J Torres, S Zunino
PURPOSE: The elective irradiation of pelvis lymph node for prostate cancer is still controversial. Including pelvic lymph node as part of the planning target volume could increase the testicular scatter dose, which could have a clinical impact. The objective of this work was to measure testicular scatter dose for prostate SBRT treatment with and without pelvic lymph nodes using TLD dosimetry. METHODS: A 6MV beam (1000UM/min) produce by a Novalis TX (BrainLAB-VARIAN) equipped HDMLC was used...
June 2016: Medical Physics
S Kry
: This presentation will highlight the upcoming TG-191 report: Clinical Use of Luminescent Dosimeters. Luminescent dosimetry based on TLD and OSLD is a practical, accurate, and precise technique for point dosimetry in medical physics applications. The charges of Task Group 191 were to detail the methodologies for practical and optimal luminescent dosimetry in a clinical setting. This includes (1) To review the variety of TLD/OSL materials available, including features and limitations of each...
June 2016: Medical Physics
S Simiele, B Palmer, L DeWerd
PURPOSE: The establishment of an air kerma rate standard at NIST for the Xoft Axxent(®) electronic brachytherapy source (Axxent(®) source) motivated the establishment of a modified TG-43 dosimetry formalism. This work measures the modified dosimetry parameters for the Axxent(®) source in the absence of a treatment applicator for implementation in Xoft's treatment planning system. METHODS: The dose-rate conversion coefficient (DRCC), radial dose function (RDF) values, and polar anisotropy (PA) were measured using TLD-100 microcubes with NIST-calibrated sources...
June 2016: Medical Physics
K Rasmussen, A Baumgarten, D Stanley, C Pelletier, M Corbett, J Jung, Y Feng, Z Huang, A Ju, T Eng, N Kirby, A Gutierrez, S Stathakis, N Papanikolaou
PURPOSE: The use of radiation as a treatment modality for skin cancer has increased significantly over the last decade with standardized applicators. Utilizing 3D printing, the ability to make applicators specifically designed for each patient's anatomy has become economically feasible. With this in mind it was the aim of this study to determine the dosimetric accuracy of a 3-D printed HDR brachytherapy applicator for the skin. METHODS: A CT reference image was used to generate a custom applicator based on an anthropomorphic head and neck phantom...
June 2016: Medical Physics
J Wang, A Rubinstein, J Ohrt, G Ibbott, Z Wen
PURPOSE: To study the effect of strong magnetic field on three types of dosimeters using an electromagnet inside a Linac vault. MATERIALS AND METHODS: Three types of dosimeters, thermoluminescent Dosimeters (TLDs), optically stimulated luminescent Dosimeters (OSLDs), and EBT3 Film were used to measure radiation dose response inside an electromagnet that could produce a strong magnetic field (B>1.5 T). The dosimeters were placed inside a plastic phantom between the two poles of the magnet, at approximately 3 meters from the iso-center of an Elekta Versa HD Linac...
June 2016: Medical Physics
D Roa, A Gonzales, J Kuo
PURPOSE: To, experimentally, corroborated the prescribed doses utilizing dosimeters (e.g. films and TLDs) that can provide high spatial resolution, allow dose measurement of multiple targets at once, and provide accurate dosimetric results. METHODS: A single-isocenter 6FFF SRS VMAT plan consisting of one 358° arc at 0° couch angle and four 179° arcs at 30°, 60°, 330° and 300° couch angles respectively, was generated in ECLIPSE v.11 using a Rando-Alderson anthropomorphic head phantom CT study...
June 2016: Medical Physics
S Li, S Ali, K Harper, Q Liang, D Serratore
PURPOSE: To correct in-vivo metal-oxide-semiconductor field-effect transistor (MOSFET) dosimeters dependence on X-ray energy, dose and dose rate, and temperature in order to measure doses or exposures on several anatomic points of interest undergoing some routine radiographs. METHODS: A mobile MOSFET system (BEST Medical) was carefully calibrated with X-ray at kVp of 70, 80, 100, 120, and 138 kVp, phantom temperatures at 0, 21, and 43 oC, and exposure range from 0...
June 2016: Medical Physics
Maud Jaccard, Kristoffer Petersson, Thierry Buchillier, Jean-François Germond, Maria Teresa Durán, Marie-Catherine Vozenin, Jean Bourhis, François O Bochud, Claude Bailat
PURPOSE: The aim of this study was to assess the suitability of Gafchromic EBT3 films for reference dose measurements in the beam of a prototype high dose-per-pulse linear accelerator (linac), capable of delivering electron beams with a mean dose-rate (Ḋm ) ranging from 0.07 to 3000 Gy/s and a dose-rate in pulse (Ḋp ) of up to 8 × 10(6) Gy/s. To do this, we evaluated the overall uncertainties in EBT3 film dosimetry as well as the energy and dose-rate dependence of their response...
December 26, 2016: Medical Physics
Reham S Sherif, Ehab M Attalla, Wael M Elshemey, Noha G Madian
INTRODUCTION: There is a growing interest in the study of radiation-induced secondary cancer. The aim of this work is (i) to estimate the peripheral doses attributable to intensity modulated radiotherapy (IMRT) and mega-voltage cone beam computed tomography (MV-CBCT) for some organs at risk (OARs) which surround the target being treated (Nasopharynx) in paediatric patients. (ii) To estimate the risk of radiation-induced secondary cancers attributable to patient setup verification imaging dose using MV-CBCT for Nasopharyngeal Carcinoma (NPC) in paediatric patients and comparing it with that attributable to the therapeutic dose using IMRT...
December 25, 2016: Journal of Medical Imaging and Radiation Oncology
Cheng-Chang Lu, Shang-Lung Dong, Hsin-Hon Lin, Yu-Ching Ni, Meei-Ling Jan, Keh-Shih Chuang
In this study, we present a new method for estimating the time-activity data using serial timely measurements of thermoluminescent dosimeters (TLDs). The approach is based on the combination of the measurement of surface dose using TLD and Monte Carlo (MC) simulation to estimate the radiopharmaceutical time-activity data. It involves four steps: (1) identify the source organs and outline their contours in computed tomography images; (2) compute the S values on the body surface for each source organ using a MC code; (3) obtain a serial measurement of the dose with numerous TLDs placed on the body surface; (4) solve the dose-activity equation to generate organ cumulative activity for each period of measurement...
February 21, 2017: Physics in Medicine and Biology
Tao Wang, Hui Wang, Huan Liu, Lei Ma, Feng-Yu Liu, Wen-Yuan Ding
The purpose of our study is to evaluate sagittal parameters in 2-level lumbar degenerative spondylolisthesis (DS) (TLDS).A total of 15 patients with TLDS, 40 patients with single-level DS (SLDS), and 30 normal volunteers as control were included in our study. All subjects performed on full spine X-ray. Two categorized data were analyzed: patient characteristics-age, sex, body mass index, radiographic parameters-pelvic incidence (PI), pelvic tilt (PT), lumbar lordosis (LL), sacral slope (SS), PI-LL, Cobb between the fifth thoracic vertebral and 12th thoracic vertebral (T5-T12), sagittal vertical axis (SVA) Cobb angle of spondylolisthesis level (CSL), ratio of PT to SS (PT/SS), CSL/LL, variation trend of SS over PI, and LL over PI...
December 2016: Medicine (Baltimore)
Sheeba Thengumpallil, Kathleen Smith, Pascal Monnin, Jean Bourhis, François Bochud, Raphaël Moeckli
The study was to describe and to compare the performance of 3D and 4D CBCT imaging modalities by measuring and analyzing the delivered dose and the image quality. The 3D (Chest) and 4D (Symmetry) CBCT Elekta XVI lung IGRT protocols were analyzed. Dose profiles were measured with TLDs inside a dedicated phantom. The dosimetric indicator cone-beam dose index (CBDI) was evaluated. The image quality analysis was performed by assessing the contrast transfer function (CTF), the noise power spectrum (NPS) and the noise-equivalent quanta (NEQ)...
November 8, 2016: Journal of Applied Clinical Medical Physics
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