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https://www.readbyqxmd.com/read/28441973/treatment-limiting-decisions-in-patients-with-severe-traumatic-brain-injury-in-a-norwegian-regional-trauma-center
#1
Annette Robertsen, Reidun Førde, Nils Oddvar Skaga, Eirik Helseth
BACKGROUND: Treatment-limiting decisions (TLD) for severe traumatic brain injury (sTBI) have been sparsely studied. This study determine prevalence, main reason for, categories and timing of TLDs in a Norwegian regional trauma setting. METHODS: A retrospective study of a 2-year cohort of 579 sTBI patients admitted to Oslo University Hospital (OUH). Prospectively collected data in the OUH Trauma Registry were combined with retrospective data from a chart review regarding TLDs...
April 26, 2017: Scandinavian Journal of Trauma, Resuscitation and Emergency Medicine
https://www.readbyqxmd.com/read/28437010/technical-note-comparison-of-peripheral-patient-dose-from-mr-guided-60-co-therapy-and-6mv-linear-accelerator-igrt
#2
Pascal Hauri, Roger A Hälg, Uwe Schneider
PURPOSE: The use of X-ray imaging in radiation therapy can give a substantial dose to the patient. A Cobalt machine combined with an magnetic resonance imaging (MRI) was recently introduced to clinical work. One positive aspect of using non-ionizing imaging devices is the reduction of the patient exposure. The purpose of this study was to quantify the difference in out-of-field dose to the patient between the image guided radiation therapy (IGRT) treatment applied with a linear accelerator with cone beam CT (CBCT) equipment and a Cobalt machine combined with an MRI...
April 24, 2017: Medical Physics
https://www.readbyqxmd.com/read/28419323/monte-carlo-simulation-used-to-calculate-energy-correction-factor-for-thermoluminescent-dosimeters-used-by-occupational-workers-on-pediatric-exams
#3
G Hoff, D Filipov, S Paschuk, H R Schelin, V Denyak
The main objective of this work is to simulate the X-ray scattered spectra by different pediatric phantoms (simulation of children subjected to barium meal procedures) to calculate an energy correction factor (ECF) to the reading of thermoluminescent dosimeters (TLDs). To perform this evaluation, the TLDs were positioned over three areas in two occupational workers: eyes, thyroid and hands. The Geant4 toolkit was used to define the spectra collected by TLDs, making possible to calculate the ECF. This work was developed in two stages: (1) evaluation of scattered spectra by different standard phantoms (newborn, 1, 5 and 10 years old); (2) definition of the ECF to the absorbed energy by each TLD...
April 13, 2017: Radiation Protection Dosimetry
https://www.readbyqxmd.com/read/28398210/out-of-field-doses-from-pediatric-craniospinal-irradiations-using-3d-crt-imrt-helical-tomotherapy-and-electron-based-therapy
#4
Marijke De Saint-Hubert, Dirk Verellen, Kenneth Poels, Wouter Crijns, Federica Magliona, Tom Depuydt, Filip Vanhavere, Lara Struelens
Medulloblastoma treatment involves irradiation of the entire central nervous system, i.e craniospinal irradiation (CSI). This is associated with significant exposure of large volumes of healthy tissue with a growing concern regarding treatment associated side effects. The current study compares out-of-field organ doses in children receiving CSI with three-dimensional-conformal radiotherapy (3D-CRT), intensity modulated radiotherapy (IMRT), helical tomotherapy (HT) and an electron-based technique, including as well radiation doses resulting from imaging performed during treatment...
April 11, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28300387/real-time-ray-casting-based-scatter-dose-estimation-for-c-arm-x-ray-system
#5
Zaid Alnewaini, Eric Langer, Philipp Schaber, Matthias David, Dominik Kretz, Volker Steil, Jürgen Hesser
OBJECTIVES: Dosimetric control of staff exposure during interventional procedures under fluoroscopy is of high relevance. In this paper, a novel ray casting approximation of radiation transport is presented and the potential and limitation vs. a full Monte Carlo transport and dose measurements are discussed. METHOD: The x-ray source of a Siemens Axiom Artix C-arm is modeled by a virtual source model using single Gaussian-shaped source. A Geant4-based Monte Carlo simulation determines the radiation transport from the source to compute scatter from the patient, the table, the ceiling and the floor...
March 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28300368/reduction-in-stray-radiation-dose-using-a-body-shielding-device-during-external-radiation-therapy
#6
Shuxu Zhang, Shaohui Jiang, Quanbin Zhang, Shengqu Lin, Ruihao Wang, Xiang Zhou, Guoqian Zhang, Huaiyu Lei, Hui Yu
With the purpose of reducing stray radiation dose (SRD) in out-of-field region (OFR) during radiotherapy with 6 MV intensity-modulated radiation therapy (IMRT), a body-shielding device (BSD) was prepared according to the measurements obtained in experimental testing. In experimental testing, optimal shielding conditions, such as 1 mm lead, 2 mm lead, and 1 mm lead plus 10 mm bolus, were investigated along the medial axis of a phantom using thermoluminescent dosimeters (TLDs). The SRDs at distances from field edge were then measured and analyzed for a clinical IMRT treatment plan for nasopharyngeal carcinoma before and after shielding using the BSD...
March 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28297279/difference-in-performance-between-3d-and-4d-cbct-for-lung-imaging-a-dose-and-image-quality-analysis
#7
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 2016: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28296300/experimental-validation-of-a-kv-source-model-and-dose-computation-method-for-cbct-imaging-in-an-anthropomorphic-phantom
#8
Yannick Poirier, Mauro Tambasco
We present an experimental validation of a kilovoltage (kV) X-ray source characterization model in an anthropomorphic phantom to estimate patient-specific absorbed dose from kV cone-beam computed tomography (CBCT) imaging procedures and compare these doses to nominal weighted CT-dose index (CTDIw) dose estimates. We simulated the default Varian on-board imager 1.4 (OBI) default CBCT imaging protocols (i.e., standard-dose head, low-dose thorax, pelvis, and pelvis spotlight) using our previously developed and easy to implement X-ray point-source model and source characterization approach...
July 2016: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28290334/gonad-dose-in-ap-pelvis-radiography-impact-of-anode-heel-orientation
#9
H A A B Mraity, A England, P Hogg
PURPOSE: For antero posterior (AP) pelvis radiographic examination, determine the impact of anode heel orientation on female/male gonad dose. METHODS: High sensitivity thermo-luminescent dosimeters (TLDs) were used with an ATOM dosimetry phantom; the phantom was positioned for AP pelvis. TLDs were placed into the testes and ovaries. Radiation dose received by these organs was measured with the feet toward anode and feet toward the cathode. kVp, mAs and SID were manipulated to generate a range of exposures...
February 2017: Radiography
https://www.readbyqxmd.com/read/28266870/evaluation-of-different-low-dose-multidetector-ct-and-cone-beam-ct-protocols-in-maxillary-sinus-imaging-part-i-an-in-vitro-study
#10
Abeer A Almashraqi, Eman A Ahmed, Nashwa S Mohamed, Imad H Barngkgei, Nader A Elsherbini, Esam S Halboub
OBJECTIVES: This in vitro study aimed to assess radiation dose and image quality of different low-dose multidetector CT (MDCT) and CBCT imaging protocols in comparison with the standard MDCT protocol for maxillary sinus imaging. METHODS: Effective dose (E) and image quality of 10 MDCT (changing effective milliampere second starting from 141.3 EmAs to 20 EmAs) and 3 CBCT protocols (changing milliampere second and voxel size) were assessed throughout scanning an anthropomorphic head and neck Alderson Rando phantom...
April 12, 2017: Dento Maxillo Facial Radiology
https://www.readbyqxmd.com/read/28242653/comparison-of-eye-lens-doses-imparted-during-interventional-and-non-interventional-neuroimaging-techniques-for-assessment-of-intracranial-aneurysms
#11
N Guberina, U Dietrich, M Forsting, A Ringelstein
BACKGROUND: A neurointerventional examination of intracranial aneurysms often involves the eye lens in the primary beam of radiation. OBJECTIVE: To assess and compare eye-lens doses imparted during interventional and non-interventional imaging techniques for the examination of intracranial aneurysms. METHODS: We performed a phantom study on an anthropomorphic phantom (ATOM dosimetry phantom 702-D; CIRS, Norfolk, Virginia, USA) and assessed eye-lens doses with thermoluminescent dosimeters (TLDs) type 100 (LiF:Mg, Ti) during (1) interventional (depiction of all cerebral arteries with triple 3D-rotational angiography and twice 2-plane DSA anteroposterior and lateral projections) and (2) non-interventional (CT angiography (CTA)) diagnosis of intracranial aneurysms...
February 27, 2017: Journal of Neurointerventional Surgery
https://www.readbyqxmd.com/read/28192281/design-of-a-head-phantom-produced-on-a-3d-rapid-prototyping-printer-and-comparison-with-a-rando-and-3m-lucite-head-phantom-in-eye-dosimetry-applications
#12
Peter Homolka, Michael Figl, Andreas Wartak, Mathias Glanzer, Martina Dünkelmeyer, 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 a 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...
April 21, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28120831/integrating-data-from-multiple-time-location-measurement-methods-for-use-in-exposure-assessment-the-multi-ethnic-study-of-atherosclerosis-and-air-pollution-mesa-air
#13
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
https://www.readbyqxmd.com/read/28090228/evaluation-of-radiation-dose-received-by-premature-neonates-admitted-to-neonatal-intensive-care-unit
#14
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
https://www.readbyqxmd.com/read/28048886/su-g-201-08-energy-response-of-thermoluminescent-microcube-dosimeters-in-water-for-kilovoltage-x-ray-beams
#15
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
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/28048839/mo-a-brb-00-tg191-clinical-use-of-luminescent-dosimeters
#17
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. (2) To outline the optimal steps to achieve accurate and precise dosimetry with luminescent detectors and to evaluate the uncertainty induced when less rigorous procedures are used...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048443/su-g-201-06-directional-low-dose-rate-brachytherapy-determination-of-the-tg-43-dose-rate-constant-analog-for-a-new-pd-103-source
#18
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
https://www.readbyqxmd.com/read/28048304/su-g-tep3-02-determination-of-geometry-specific-backscatter-factors-for-radiobiology-studies
#19
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
https://www.readbyqxmd.com/read/28048209/su-f-p-55-testicular-scatter-dose-determination-during-prostate-sbrt-with-and-without-pelvic-lymph-nodes
#20
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
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