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https://www.readbyqxmd.com/read/28110197/outdoor-dose-rate-mapping-in-kuwait
#1
Darwish Al-Azmi
As part of ongoing efforts to develop the data base required for the gamma dose rate baseline in Kuwait, a survey of ambient outdoor gamma-ray dose rates was carried out in 112 locations within the country. Measurements were performed, during the period from August 2013 to March 2016, in various undisturbed open areas in the desert using a NaI dosimeter/spectrometer. The dose rates were recorded along with the corresponding gamma-ray spectra for in-situ relative contribution of the primordial radionuclides and (137)Cs in the outdoor environment...
January 19, 2017: Journal of Environmental Radioactivity
https://www.readbyqxmd.com/read/28104641/measured-head-ct-cta-skin-dose-and-intensive-care-unit-patient-cumulative-exposure
#2
R D Nawfel, G S Young
BACKGROUND AND PURPOSE: Estimates of cumulative CT/CTA radiation dose based on volumetric CT dose index have raised concern that neurological intensive care unit patient exposures may reach thresholds for deterministic skin injury. Because the accuracy of volumetric CT dose index for this purpose in unknown, we set out to directly measure head CT and CTA peak skin dose, assess the relationship of volumetric CT dose index to measured peak skin dose, and determine whether multiple CT/CTA exposures in typical patients in the neurological intensive care unit produce cumulative doses approaching or exceeding single-dose deterministic thresholds for skin injury...
January 19, 2017: AJNR. American Journal of Neuroradiology
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/28102349/development-of-patient-specific-phantoms-for-verification-of-stereotactic-body-radiation-therapy-planning-in-patients-with-metallic-screw-fixation
#4
Dongryul Oh, Chae-Seon Hong, Sang Gyu Ju, Minkyu Kim, Bum Yong Koo, SungBack Choi, Hee Chul Park, Doo Ho Choi, Hongryull Pyo
A new technique for manufacturing a patient-specific dosimetric phantom using three-dimensional printing (PSDP_3DP) was developed, and its geometrical and dosimetric accuracy was analyzed. External body contours and structures of the spine and metallic fixation screws (MFS) were delineated from CT images of a patient with MFS who underwent stereotactic body radiation therapy for spine metastasis. Contours were converted into a STereoLithography file format using in-house program. A hollow, four-section PSDP was designed and manufactured using three types of 3DP to allow filling with a muscle-equivalent liquid and insertion of dosimeters...
January 19, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28098666/estimated-internal-and-external-radiation-exposure-of-caregivers-of-patients-with-pediatric-neuroblastoma-undergoing-131i-metaiodobenzylguanidine-therapy-a-prospective-pilot-study
#5
Sangwon Han, Seon Hee Yoo, Kyung-Nam Koh, Jong Jin Lee
PURPOSE: Current recommendations suggest that family members should participate in the care of children receiving in-hospital I metaiodobenzylguanidine (MIBG) therapy for neuroblastoma. The present study aimed to measure the external radiation exposure and estimate the internal radiation exposure of caregivers during the hospital stay for I MIBG therapy. MATERIALS AND METHODS: Caregivers received radiation safety instructions and a potassium iodide solution for thyroid blockade before patient admission...
January 16, 2017: Clinical Nuclear Medicine
https://www.readbyqxmd.com/read/28097673/schoolyard-shade-and-sun-exposure-assessment-of-personal-monitoring-during-children-s-physical-activity
#6
Jennifer K Vanos, Grant R McKercher, Kylie Naughton, Marc Lochbaum
Childhood exposure to ultraviolet radiation (UVR) is a major risk factor for the development of melanoma later in life. However, it is challenging to accurately determine personal outdoor exposure to UVR, specifically erythemally-weighted UVR (UVEry ), due to technological constraints, variable time-activity patterns, and the influence of outdoor environmental design. To address this challenge, the current study utilized mobile and stationary techniques to examine the UVEry exposures of 14 children in a schoolyard in Lubbock, TX in spring 2016...
January 18, 2017: Photochemistry and Photobiology
https://www.readbyqxmd.com/read/28095022/estimating-effective-dose-of-radiation-from-pediatric-cardiac-ct-angiography-using-a-64-mdct-scanner-new-conversion-factors-relating-dose-length-product-to-effective-dose
#7
Sigal Trattner, Anjali Chelliah, Peter Prinsen, Carrie B Ruzal-Shapiro, Yanping Xu, Sachin Jambawalikar, Maxwell Amurao, Andrew J Einstein
OBJECTIVE: The purpose of this study is to determine the conversion factors that enable accurate estimation of the effective dose (ED) used for cardiac 64-MDCT angiography performed for children. MATERIALS AND METHODS: Anthropomorphic phantoms representative of 1- and 10-year-old children, with 50 metal oxide semiconductor field-effect transistor dosimeters placed in organs, underwent scanning performed using a 64-MDCT scanner with different routine clinical cardiac scan modes and x-ray tube potentials...
January 17, 2017: AJR. American Journal of Roentgenology
https://www.readbyqxmd.com/read/28094855/technical-note-dose-distributions-in-the-vicinity-of-high-density-implants-using-3d-gel-dosimeters
#8
Andre Asena, Shaun Thomas Smith, Tanya Kairn, Scott Bradley Crowe, Kazuyuki Hosokawa, Steven Sylvander, Jamie Vincent Trapp
PURPOSE: In this work, we develop a methodology for using Fricke gel dosimeters for dose distribution measurements surrounding high-density implants which circumvents artefact production by removing the obstruction during imaging. METHODS: Custom 3D printed moulds were used to set cavities in Fricke gel phantoms to allow for the suspension of high density implants in different geometries. This allowed for the metal valve extracted from a temporary tissue expander to be suspended during irradiation, and removed during optical-CT scanning...
January 17, 2017: Medical Physics
https://www.readbyqxmd.com/read/28094138/new-normoxic-n-hydroxymethyl-acrylamide-based-polymer-gel-for-3d-dosimetry-in-radiation-therapy
#9
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/28090228/evaluation-of-radiation-dose-received-by-premature-neonates-admitted-to-neonatal-intensive-care-unit
#10
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/28089526/a-feasibility-study-of-2-mm-bolus-for-postmastectomy-radiation-therapy
#11
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/28081000/on-the-development-of-a-vipar-nd-radiotherapy-3d-polymer-gel-dosimeter
#12
Marek Kozicki, Malwina Jaszczak, Piotr Maras, Mariusz Dudek, Marian Cłapa
This work presents an improvement of the VIPAR(nd) ('nd' stands for 'normoxic, double', or VIP) polymer gel dosimeter. The gel composition was altered by increasing the concentration of the monomeric components, N-vinylpyrrolidone (NVP) and N,N'-methylenebisacrylamide (MBA), in co-solvent solutions. The optimal composition (VIPAR(CT), where 'CT' stands for computed tomography, or VIC) comprised: 17% NVP, 8% MBA, 12% t-BuOH, 7.5% gelatine, 0.007% ascorbic acid, 0.0008% CuSO4  ×  5H2O and 0.02% hydroquinone...
February 7, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28074019/point-organ-radiation-dose-in-abdominal-ct-effect-of-patient-off-centering-in-an-experimental-human-cadaver-study
#13
Ranish Deedar Ali Khawaja, Sarabjeet Singh, Atul Padole, Alexi Otrakji, Diego Lira, Da Zhang, Bob Liu, Andrew Primak, George Xu, Mannudeep K Kalra
To determine the effect of patient off-centering on point organ radiation dose measurements in a human cadaver scanned with routine abdominal CT protocol. A human cadaver (88 years, body-mass-index 20 kg/m(2)) was scanned with routine abdominal CT protocol on 128-slice dual source MDCT (Definition Flash, Siemens). A total of 18 scans were performed using two scan protocols (a) 120 kV-200 mAs fixed-mA (CTDIvol 14 mGy) (b) 120 kV-125 ref mAs (7 mGy) with automatic exposure control (AEC, CareDose 4D) at three different positions (a) gantry isocenter, (b) upward off-centering and (c) downward off-centering...
January 10, 2017: Radiation Protection Dosimetry
https://www.readbyqxmd.com/read/28074018/evaluation-of-dose-homogeneity-in-cone-beam-breast-computed-tomography
#14
Giovanni Mettivier, Matilde Costa, Nico Lanconelli, Anna Ianiro, Mariagabriella Pugliese, Maria Quarto, Paolo Russo
The aim of this study is to determine, via measurements on phantoms and Monte Carlo (MC) simulations, the dose distribution of absorbed dose in a cone-beam breast computed tomography scan. The absorbed dose volume distribution was measured inside a polyethylene cylindrical phantom, simulating adipose breast tissue, using LiF:Mg,Ti thermoluminescence dosimeters. A reasonable agreement (between 2 and 8%) between the simulated and measured data was observed. The 3D distribution of absorbed dose was evaluated at 40, 60 and 80 kV in a phantom simulating a pendant breast...
January 10, 2017: Radiation Protection Dosimetry
https://www.readbyqxmd.com/read/28060829/enhancement-of-dose-response-and-nuclear-magnetic-resonance-image-of-pagat-polymer-gel-dosimeter-by-adding-silver-nanoparticles
#15
Rahim Sabbaghizadeh, Roslinda Shamsudin, Najmeh Deyhimihaghighi, Arman Sedghi
In the present study, the normoxic polyacrylamide gelatin and tetrakis hydroxy methyl phosphoniun chloride (PAGAT) polymer gel dosimeters were synthesized with and without the presence of silver (Ag) nanoparticles. The amount of Ag nanoparticles varied from 1 to 3 ml with concentration 3.14 g/l, thus forming two types of PAGAT polymer gel dosimeters before irradiating them with 6 to 25 Gy produced by 1.25-MeV 60Co gamma rays. In this range, the predominant gamma ray interaction with matter is by Compton scattering effect, as the photoelectric absorption effect diminishes...
2017: PloS One
https://www.readbyqxmd.com/read/28056335/effects-of-handling-and-environment-on-preterm-newborns-sleeping-in-incubators
#16
Kelly Cristina Sbampato Calado Orsi, Marta José Avena, Marcia Lurdes de Cacia Pradella-Hallinan, Mavilde da Luz Gonçalves Pedreira, Miriam Harumi Tsunemi, Ariane Ferreira Machado Avelar, Eliana Moreira Pinheiro
OBJECTIVE: To describe the total sleep time, stages of sleep, and wakefulness of preterm newborns and correlate them to levels of sound pressure, light, temperature, relative air humidity, and handling inside incubators. DESIGN: Observational, correlational study. SETTING: A neonatal intermediate care unit. PARTICIPANTS: Twelve preterm newborns, who were 32.2 ± 4.2 weeks gestational age and weighed 1,606 ± 317 g. METHODS: Sleep records were assessed by polysomnograph...
January 2, 2017: Journal of Obstetric, Gynecologic, and Neonatal Nursing: JOGNN
https://www.readbyqxmd.com/read/28048924/mo-b-brb-02-3d-dosimetry-in-the-clinic-imrt-technique-validation-in-sweden
#17
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/28048886/su-g-201-08-energy-response-of-thermoluminescent-microcube-dosimeters-in-water-for-kilovoltage-x-ray-beams
#18
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
#19
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/28048873/su-f-t-32-evaluation-of-the-performance-of-a-multiple-array-diode-detector-for-quality-assurance-tests-in-high-dose-rate-brachytherapy-with-ir-192-source
#20
K Harpool, T De La Fuente Herman, S Ahmad, I Ali
PURPOSE: To evaluate the performance of a two-dimensional (2D) array-diode- detector for geometric and dosimetric quality assurance (QA) tests of high-dose-rate (HDR) brachytherapy with an Ir-192-source. METHODS: A phantom setup was designed that encapsulated a two-dimensional (2D) array-diode-detector (MapCheck2) and a catheter for the HDR brachytherapy Ir-192 source. This setup was used to perform both geometric and dosimetric quality assurance for the HDR-Ir192 source...
June 2016: Medical Physics
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