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  1 / 25524 MEDLINE  
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[PMID]:29216961
[Au] Autor:Li S; Lu X; Feng JB; Tian M; Liu QJ
[Ad] Endereço:China CDC Key Laboratory of Radiological Protection and Nuclear Emergency, National Institute for Radiological Protection, Chinese Center for Disease Control and Prevention, Beijing 100088, China.
[Ti] Título:Identification and Validation of Candidate Radiation-responsive Genes for Human Biodosimetr.
[So] Source:Biomed Environ Sci;30(11):834-840, 2017 Nov.
[Is] ISSN:0895-3988
[Cp] País de publicação:Netherlands
[La] Idioma:eng
[Ab] Resumo:The aim of the present study is to analyze the global research trend of radiation-responsive genes and identify the highly reproducible radiation-responsive genes. Bibliometric methods were applied to analyze the global research trend of radiation-responsive genes. We found 79 publications on radiation-responsive genes from 2000 to 2017. A total of 35 highly reproducible radiation-responsive genes were identified. Most genes are involved in response to DNA damage, cell proliferation, cell cycle regulation, and DNA repair. The p53 signal pathway was the top enriched pathway. The expression levels of 18 genes in human B lymphoblastoid cell line (AHH-1) cells were significantly up-regulated in a dose-dependent manner at 24 h after exposure to 0-5 Gy 60Co γ-ray irradiation. Our results indicate that developing a gene expression panel with the 35 high reproducibility radiation-responsive genes may be necessary for qualitative and quantitative assessment after exposure.
[Mh] Termos MeSH primário: Regulação da Expressão Gênica/efeitos da radiação
Radiometria/métodos
[Mh] Termos MeSH secundário: Relação Dose-Resposta à Radiação
Perfilação da Expressão Gênica
Seres Humanos
Reprodutibilidade dos Testes
Regulação para Cima/efeitos da radiação
[Pt] Tipo de publicação:JOURNAL ARTICLE; META-ANALYSIS; REVIEW
[Em] Mês de entrada:1803
[Cu] Atualização por classe:180305
[Lr] Data última revisão:
180305
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:171209
[St] Status:MEDLINE
[do] DOI:10.3967/bes2017.112


  2 / 25524 MEDLINE  
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[PMID]:28742061
[Au] Autor:Poppinga D; Halbur J; Lemmer S; Delfs B; Harder D; Looe HK; Poppe B
[Ad] Endereço:University Clinic for Medical Radiation Physics, Medical Campus Pius-Hospital, Carl von Ossietzky University, Oldenburg, Germany.
[Ti] Título:Test study of boron nitride as a new detector material for dosimetry in high-energy photon beams.
[So] Source:Phys Med Biol;62(18):N436-N444, 2017 Sep 05.
[Is] ISSN:1361-6560
[Cp] País de publicação:England
[La] Idioma:eng
[Ab] Resumo:The aim of this test study is to check whether boron nitride (BN) might be applied as a detector material in high-energy photon-beam dosimetry. Boron nitride exists in various crystalline forms. Hexagonal boron nitride (h-BN) possesses high mobility of the electrons and holes as well as a high volume resistivity, so that ionizing radiation in the clinical range of the dose rate can be expected to produce a measurable electrical current at low background current. Due to the low atomic numbers of its constituents, its density (2.0 g cm ) similar to silicon and its commercial availability, h-BN appears as possibly suitable for the dosimetry of ionizing radiation. Five h-BN plates were contacted to triaxial cables, and the detector current was measured in a solid-state ionization chamber circuit at an applied voltage of 50 V. Basic dosimetric properties such as formation by pre-irradiation, sensitivity, reproducibility, linearity and temporal resolution were measured with 6 MV photon irradiation. Depth dose curves at quadratic field sizes of 10 cm and 40 cm were measured and compared to ionization chamber measurements. After a pre-irradiation with 6 Gy, the devices show a stable current signal at a given dose rate. The current-voltage characteristic up to 400 V shows an increase in the collection efficiency with the voltage. The time-resolved detector current behavior during beam interrupts is comparable to diamond material, and the background current is negligible. The measured percentage depth dose curves at 10 cm × 10 cm field size agreed with the results of ionization chamber measurements within ±2%. This is a first study of boron nitride as a detector material for high-energy photon radiation. By current measurements on solid ionization chambers made from boron nitride chips we could demonstrate that boron nitride is in principle suitable as a detector material for high-energy photon-beam dosimetry.
[Mh] Termos MeSH primário: Compostos de Boro/química
Teste de Materiais
Fótons/uso terapêutico
Radiometria/instrumentação
Radiometria/métodos
Radioterapia de Alta Energia/instrumentação
[Mh] Termos MeSH secundário: Diamante/química
Elétrons
Reprodutibilidade dos Testes
Silício/química
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Boron Compounds); 2U4T60A6YD (boron nitride); 7782-40-3 (Diamond); Z4152N8IUI (Silicon)
[Em] Mês de entrada:1803
[Cu] Atualização por classe:180305
[Lr] Data última revisão:
180305
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170726
[St] Status:MEDLINE
[do] DOI:10.1088/1361-6560/aa81f7


  3 / 25524 MEDLINE  
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[PMID]:28741595
[Au] Autor:Simeonov Y; Weber U; Penchev P; Ringbæk TP; Schuy C; Brons S; Engenhart-Cabillic R; Bliedtner J; Zink K
[Ad] Endereço:Institute of Medical Physics and Radiation Protection (IMPS), University of Applied Sciences, Giessen, Germany.
[Ti] Título:3D range-modulator for scanned particle therapy: development, Monte Carlo simulations and experimental evaluation.
[So] Source:Phys Med Biol;62(17):7075-7096, 2017 Aug 11.
[Is] ISSN:1361-6560
[Cp] País de publicação:England
[La] Idioma:eng
[Ab] Resumo:The purpose of this work was to design and manufacture a 3D range-modulator for scanned particle therapy. The modulator is intended to create a highly conformal dose distribution with only one fixed energy, simultaneously reducing considerably the treatment time. As a proof of concept, a 3D range-modulator was developed for a spherical target volume with a diameter of 5 cm, placed at a depth of 25 cm in a water phantom. It consists of a large number of thin pins with a well-defined shape and different lengths to modulate the necessary shift of the Bragg peak. The 3D range-modulator was manufactured with a rapid prototyping technique. The FLUKA Monte Carlo package was used to simulate the modulating effect of the 3D range-modulator and the resulting dose distribution. For that purpose, a special user routine was implemented to handle its complex geometrical contour. Additionally, FLUKA was extended with the capability of intensity modulated scanning. To validate the simulation results, dose measurements were carried out at the Heidelberg Ion Beam Therapy Center with a 400.41 MeV/u C beam. The high resolution dosimetric measurements show a good agreement between simulated and measured dose distributions. Irradiation of the monoenergetic raster plan took 3 s, which is approximately 20 times shorter than a comparable plan with 16 different energies. The combination of only one energy and a 3D range-modulator leads to a tremendous decrease in irradiation time. 'Interplay effects', typical for moving targets and pencil beam scanning, can be immensely reduced or disappear completely, making the delivery of a homogeneous dose to moving targets more reliable. Combining high dose conformity, very good homogeneity and extremely short irradiation times, the 3D range-modulator is considered to become a clinically applicable method for very fast treatment of lung tumours.
[Mh] Termos MeSH primário: Radioterapia com Íons Pesados
Método de Monte Carlo
Imagens de Fantasmas
Radiometria/instrumentação
Planejamento da Radioterapia Assistida por Computador/métodos
[Mh] Termos MeSH secundário: Seres Humanos
Radiometria/métodos
Dosagem Radioterapêutica
Água
[Pt] Tipo de publicação:EVALUATION STUDIES; JOURNAL ARTICLE
[Nm] Nome de substância:
059QF0KO0R (Water)
[Em] Mês de entrada:1803
[Cu] Atualização por classe:180305
[Lr] Data última revisão:
180305
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170726
[St] Status:MEDLINE
[do] DOI:10.1088/1361-6560/aa81f4


  4 / 25524 MEDLINE  
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[PMID]:29182384
[Au] Autor:King RB; Osman SO; Fairmichael C; Irvine DM; Lyons CA; Ravi A; O'Sullivan JM; Hounsell AR; Mitchell DM; McGarry CK; Jain S
[Ad] Endereço:1 Centre for Cancer Research and Cell Biology, Queen's University Belfast , Belfast , Ireland.
[Ti] Título:Efficacy of a rectal spacer with prostate SABR-first UK experience.
[So] Source:Br J Radiol;91(1083):20170672, 2018 Feb.
[Is] ISSN:1748-880X
[Cp] País de publicação:England
[La] Idioma:eng
[Ab] Resumo:OBJECTIVE: This study assessed the use of implanted hydrogel rectal spacers for stereotactic ablative radiotherapy-volumetric modulated arc therapy (SABR-VMAT) patients, investigating practicality, dosimetric impact, normal tissue complication probability (NTCP) and early toxicity. METHODS: Data from the first 6 patients treated within a prostate SABR and rectal spacer trial were examined to determine spacer insertion tolerability, resultant changes in treatment planning and dosimetry and early toxicity effects. CT scans acquired prior to spacer insertion were used to generate SABR plans which were compared to post-insertion plans. Plans were evaluated for target coverage, conformity, and organs at risk doses with NTCPs also determined from resultant dose fluences. Early toxicity data were also collected. RESULTS: All patients had successful spacer insertion under local anaesthetic with maximal Grade 1 toxicity. All plans were highly conformal, with no significant differences in clinical target volume dose coverage between pre- and post-spacer plans. Substantial improvements in rectal dose metrics were observed in post-spacer plans, e.g. rectal volume receiving 36 Gy reduced by ≥42% for all patients. Median NTCP for Grade 2 + rectal bleeding significantly decreased from 4.9 to 0.8% with the use of a rectal spacer (p = 0.031). To date, two episodes of acute Grade 1 proctitis have been reported following treatment. CONCLUSION: The spacer resulted in clinically and statistically significant reduction in rectal doses for all patients. Advances in knowledge: This is one of the first studies to investigate the efficacy of a hydrogel spacer in prostate SABR treatments. Observed dose sparing of the rectum is predicted to result in meaningful clinical benefit.
[Mh] Termos MeSH primário: Adenocarcinoma/radioterapia
Neoplasias da Próstata/radioterapia
Próteses e Implantes
Lesões por Radiação/prevenção & controle
Radiocirurgia/métodos
Radioterapia de Intensidade Modulada/métodos
Reto/efeitos da radiação
[Mh] Termos MeSH secundário: Adenocarcinoma/patologia
Adulto
Idoso
Biópsia
Marcadores Fiduciais
Seres Humanos
Hidrogel de Polietilenoglicol-Dimetacrilato
Imagem por Ressonância Magnética
Masculino
Meia-Idade
Gradação de Tumores
Estadiamento de Neoplasias
Tratamentos com Preservação do Órgão
Órgãos em Risco
Neoplasias da Próstata/patologia
Radiometria
Dosagem Radioterapêutica
Reto/diagnóstico por imagem
Tomografia Computadorizada por Raios X
Resultado do Tratamento
Reino Unido
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
25852-47-5 (Hydrogel, Polyethylene Glycol Dimethacrylate)
[Em] Mês de entrada:1802
[Cu] Atualização por classe:180226
[Lr] Data última revisão:
180226
[Sb] Subgrupo de revista:AIM; IM
[Da] Data de entrada para processamento:171129
[St] Status:MEDLINE
[do] DOI:10.1259/bjr.20170672


  5 / 25524 MEDLINE  
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[PMID]:28469106
[Au] Autor:Yao LH; Wang JJ; Shang C; Jiang P; Lin L; Sun HT; Liu L; Liu H; He D; Yang RJ
[Ad] Endereço:Department of Radiation Oncology, Peking University Third Hospital, Beijing 100191, China.
[Ti] Título: Dosimetric Study of Biliary Stent Loaded with Radioactive I Seeds.
[So] Source:Chin Med J (Engl);130(9):1093-1099, 2017 May 05.
[Is] ISSN:0366-6999
[Cp] País de publicação:China
[La] Idioma:eng
[Ab] Resumo:BACKGROUND: A novel radioactive 125I seed-loaded biliary stent has been used for patients with malignant biliary obstruction. However, the dosimetric characteristics of the stents remain unclear. Therefore, we aimed to describe the dosimetry of the stents of different lengths - with different number as well as activities of 125I seeds. METHODS: The radiation dosimetry of three representative radioactive stent models was evaluated using a treatment planning system (TPS), thermoluminescent dosimeter (TLD) measurements, and Monte Carlo (MC) simulations. In the process of TPS calculation and TLD measurement, two different water-equivalent phantoms were designed to obtain cumulative radial dose distribution. Calibration procedures using TLD in the designed phantom were also conducted. MC simulations were performed using the Monte Carlo N-Particle eXtended version 2.5 general purpose code to calculate the radioactive stent's three-dimensional dose rate distribution in liquid water. Analysis of covariance was used to examine the factors influencing radial dose distribution of the radioactive stent. RESULTS: The maximum reduction in cumulative radial dose was 26% when the seed activity changed from 0.5 mCi to 0.4 mCi for the same length of radioactive stents. The TLD's dose response in the range of 0-10 mGy irradiation by 137Cs γ-ray was linear: y = 182225x - 6651.9 (R2=0.99152; y is the irradiation dose in mGy, x is the TLDs' reading in nC). When TLDs were irradiated by different energy radiation sources to a dose of 1 mGy, reading of TLDs was different. Doses at a distance of 0.1 cm from the three stents' surface simulated by MC were 79, 93, and 97 Gy. CONCLUSIONS: TPS calculation, TLD measurement, and MC simulation were performed and were found to be in good agreement. Although the whole experiment was conducted in water-equivalent phantom, data in our evaluation may provide a theoretical basis for dosimetry for the clinical application.
[Mh] Termos MeSH primário: Dosimetria Termoluminescente/métodos
[Mh] Termos MeSH secundário: Braquiterapia/métodos
Simulação por Computador
Seres Humanos
Método de Monte Carlo
Radiometria/métodos
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Em] Mês de entrada:1802
[Cu] Atualização por classe:180226
[Lr] Data última revisão:
180226
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170505
[St] Status:MEDLINE
[do] DOI:10.4103/0366-6999.204936


  6 / 25524 MEDLINE  
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[PMID]:29177263
[Au] Autor:Cheki M; Gali H
[Ad] Endereço:Department of Radiologic Technology, Faculty of Paramedicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran. mohsencheky@gmail.com.
[Ti] Título:Primary radiation dosimetry of a novel PET radiopharmaceutical Ga-NODAGA-glycine in comparison with Tc-DTPA in renal studies.
[So] Source:Hell J Nucl Med;20(3):241-246, 2017 Sep-Dec.
[Is] ISSN:1790-5427
[Cp] País de publicação:Greece
[La] Idioma:eng
[Ab] Resumo:OBJECTIVE: In this study, we tried to estimate human absorbed dose of Ga-NODAGA-glycine as a new potential positron emission tomography (PET) renal agent based on the biodistribution data reported in healthy rats, and compare our estimation with the available absorbed dose data from technetium-99m-diethylenetriaminepentaacetic acid ( Tc-DTPA). SUBJECTS AND METHODS: The medical internal radiation dose (MIRD) formulation was applied to extrapolate from rats to human and to project the absorbed radiation dose for various organs in humans. S factor calculated by Monte-Carlo N-particle (MCNP) simulation and also this factor has been taken from the tables presented in MIRD pamphlet No.11. Hence, two radiation absorbed dose were calculated for organs. RESULTS: Our dose prediction shows that an 185MBq injection of gallium-68-1,4,7-triazacyclononane-1-γ-glutamylglycine-4,7-diacetic acid ( Ga-NODAGA-glycine) in humans might result in an estimated absorbed dose of 0.063mGy in the whole body when S factor calculated by MCNP simulation. The highest absorbed doses are observed in kidneys, lungs, spleen, liver, and red marrow with 3.510, 0.453, 0.335, 0.268, and 0.239mGy, respectively. In addition to, the estimated absorbed dose for total body after injection of 185MBq of Ga-NODAGA-glycine is 0.053mGy when S factor has been taken from MIRD pamphlet No.11. The highest absorbed doses are observed in kidneys, lungs, liver, spleen, and red marrow with 3.110, 0.438, 0.209, 0.203, and 0.203mGy, respectively. Comparison between human absorbed dose estimation for Ga-NODAGA-glycine and Tc-DTPA indicated that the absorbed dose of the most organs after injection of Tc-DTPA is higher than the amount after Ga-NODAGA-glycine. CONCLUSION: The results showed that Ga-NODAGA-glycine delivers lower dose to the patients. Also due to its application in PET (which offers higher sensitivity and spatial resolution compared to planar or SPET), Ga-NODAGA-glycine would be a superior choice than Tc-DTPA for renography and impose less radiation doses to patients.
[Mh] Termos MeSH primário: Absorção de Radiação/fisiologia
Complexos de Coordenação/farmacocinética
Glicina/análogos & derivados
Compostos Heterocíclicos com 1 Anel/farmacocinética
Rim/metabolismo
Modelos Biológicos
Tomografia por Emissão de Pósitrons/métodos
Radiometria/métodos
Pentetato de Tecnécio Tc 99m/farmacocinética
[Mh] Termos MeSH secundário: Animais
Simulação por Computador
Glicina/farmacocinética
Seres Humanos
Rim/diagnóstico por imagem
Especificidade de Órgãos/fisiologia
Projetos Piloto
Dose de Radiação
Exposição à Radiação/análise
Compostos Radiofarmacêuticos/farmacocinética
Ratos
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (68Ga-NODAGA-glycine); 0 (Coordination Complexes); 0 (Heterocyclic Compounds, 1-Ring); 0 (Radiopharmaceuticals); TE7660XO1C (Glycine); VW78417PU1 (Technetium Tc 99m Pentetate)
[Em] Mês de entrada:1802
[Cu] Atualização por classe:180223
[Lr] Data última revisão:
180223
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:171128
[St] Status:MEDLINE
[do] DOI:10.1967/s002449910609


  7 / 25524 MEDLINE  
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[PMID]:29394013
[Au] Autor:Qu X; Zhao X; Chen Z
[Ti] Título:A new in vitro method to determine sun protection factor.
[So] Source:J Cosmet Sci;67(2):101-08, 2016 Mar-Apr.
[Is] ISSN:1525-7886
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:A new in vitro sun protection factor (SPF) test method to determine the efficacy of sun care products is proposed and evaluated. Based on ultraviolet (UV) dose cumulate response protocols, the new method employs Gafchromic EBT3 film, a self-developing dosimetry film originally created for applications in radiotherapy. Unlike the current standardized method, a UV spectrophotometer is not required. In vitro SPF values of 15 commercial products were measured with EBT3 film and compared with labeled in vivo SPF values. It is apparent that the new method is accurate, cost-effective, and reproducible. These results can be seen across sun care product lines, including sunscreen lotions, blemish balm (BB) creams, foundations, and sprays with organic and\/or inorganic UV filters.
[Mh] Termos MeSH primário: Radiometria/métodos
Fator de Proteção Solar/métodos
Protetores Solares/análise
[Mh] Termos MeSH secundário: Seres Humanos
Dose de Radiação
Pele/efeitos da radiação
Raios Ultravioleta/efeitos adversos
Filme para Raios X
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Sunscreening Agents)
[Em] Mês de entrada:1802
[Cu] Atualização por classe:180222
[Lr] Data última revisão:
180222
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:180203
[St] Status:MEDLINE


  8 / 25524 MEDLINE  
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[PMID]:29290555
[Au] Autor:Ben Salem L; Essadok A; Saidani I; Mahdouani M; Benna M; Mahjoubi K; Besbes M; Benna F
[Ad] Endereço:Unité de radiophysique, service de radiothérapie, institut Salah-Azaiz de Tunis, boulevard 9-Avril, 1006 Tunis, Tunisie. Electronic address: lotfi.bsalem@gmail.com.
[Ti] Título:[Experimental determination of correction factors of four detectors used in small field radiotherapy].
[Ti] Título:Détermination expérimentale des facteurs de correction de quatre détecteurs actifs utilisés pour la dosimétrie des minifaisceaux utilisés en radiothérapie..
[So] Source:Cancer Radiother;22(1):45-51, 2018 Feb.
[Is] ISSN:1769-6658
[Cp] País de publicação:France
[La] Idioma:fre
[Ab] Resumo:PURPOSE: The aim of this work is to determine experimentally the correction factors [Formula: see text] for four active commercial dosimeters: two microchambers and two diode detectors based on the output factor measured with radiochromic film for a radiotherapy linear accelerator equipped with circular cones. MATERIALS AND METHODS: Initially, a radiochromic film dosimetry measurement protocol with an accuracy of 2% was developed to approach the "reference output factor". Afterwards, the corrective factors of four detectors were determined for two ionization chambers (PinPoint PTW 31016 3D, Micropoint Extradin A16) and two diodes (PTW T60017 Diode, PTW-60019 Micro-Diamond). These measurements were carried out under conical BrainLAB collimators defining circular fields with diameters equal to 7.5mm, 10mm, 12.5mm, 15mm, 17.5mm, 20mm, 25mm, 30mm, 35mm and 45mm of a 6MV X-ray beam generated by the ClinaciX linear accelerator (Varian ). These factors are weakly dependent on the type of accelerator, whether the model and the collimation type. This allowed their comparisons with those published for the same type of detector and for an accelerator with the same index of beam quality. RESULTS: The correction factors obtained experimentally were comparable in maximum deviation of 1.9% with published ones of the works using the same type of detector (mark and model) and an accelerator delivering the same beam quality for the same field size at the measurement point. CONCLUSION: The measurement protocol using the EBT3 film, which was used as a passive dosimeter to determine the "reference output factor", was validated by comparing measured and published data of active detector correction factors.
[Mh] Termos MeSH primário: Radiometria/instrumentação
[Mh] Termos MeSH secundário: Seres Humanos
Método de Monte Carlo
Aceleradores de Partículas
Radiocirurgia
Planejamento da Radioterapia Assistida por Computador
Software
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Em] Mês de entrada:1802
[Cu] Atualização por classe:180220
[Lr] Data última revisão:
180220
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:180102
[St] Status:MEDLINE


  9 / 25524 MEDLINE  
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[PMID]:28749809
[Au] Autor:Piper RK; Mozhayev AV; Murphy MK; Thompson AK
[Ad] Endereço:*Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA 99352; †National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD 20899.
[Ti] Título:Beyond Californium-A Neutron Generator Alternative for Dosimetry and Instrument Calibration in the U.S.
[So] Source:Health Phys;113(3):183-194, 2017 09.
[Is] ISSN:1538-5159
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:Evaluations of neutron survey instruments, area monitors, and personal dosimeters rely on reference neutron radiations, which have evolved from the heavy reliance on (α,n) sources to a shared reliance on (α,n) and the spontaneous fission neutrons of californium-252 (Cf). Capable of producing high dose equivalent rates from an almost point source geometry, the characteristics of Cf are generally more favorable when compared to the use of (α,n) and (γ,n) sources or reactor-produced reference neutron radiations. Californium-252 is typically used in two standardized configurations: unmoderated, to yield a fission energy spectrum; or with the capsule placed within a heavy-water moderating sphere to produce a softened spectrum that is generally considered more appropriate for evaluating devices used in nuclear power plant work environments. The U.S. Department of Energy Cf Loan/Lease Program, a longtime origin of affordable Cf sources for research, testing and calibration, was terminated in 2009. Since then, high-activity sources have become increasingly cost-prohibitive for laboratories that formerly benefited from that program. Neutron generators, based on the D-T and D-D fusion reactions, have become economically competitive with Cf and are recognized internationally as important calibration and test standards. Researchers from the National Institute of Standards and Technology and the Pacific Northwest National Laboratory are jointly considering the practicality and technical challenges of implementing neutron generators as calibration standards in the U.S. This article reviews the characteristics of isotope-based neutron sources, possible isotope alternatives to Cf, and the rationale behind the increasing favor of electronically generated neutron options. The evaluation of a D-T system at PNNL has revealed characteristics that must be considered in adapting generators to the task of calibration and testing where accurate determination of a dosimetric quantity is necessary. Finally, concepts are presented for modifying the generated neutron spectra to achieve particular targeted spectra, simulating Cf or workplace environments.
[Mh] Termos MeSH primário: Califórnio/química
Nêutrons
Radiometria/instrumentação
[Mh] Termos MeSH secundário: Calibragem
Aceleradores de Partículas
Estados Unidos
[Pt] Tipo de publicação:JOURNAL ARTICLE; RESEARCH SUPPORT, U.S. GOV'T, NON-P.H.S.
[Nm] Nome de substância:
975X05H15A (Californium)
[Em] Mês de entrada:1708
[Cu] Atualização por classe:180214
[Lr] Data última revisão:
180214
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170728
[St] Status:MEDLINE
[do] DOI:10.1097/HP.0000000000000689


  10 / 25524 MEDLINE  
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[PMID]:28705533
[Au] Autor:Agounad S; Aassif EH; Khandouch Y; Maze G; Décultot D
[Ad] Endereço:Laboratory of Metrology and Information Processing, Department of Physics, Ibn Zohr University, B.P. 8106, 80000 Agadir, Morocco. Electronic address: said.agounad@edu.uiz.ac.ma.
[Ti] Título:Characterization and prediction of the backscattered form function of an immersed cylindrical shell using hybrid fuzzy clustering and bio-inspired algorithms.
[So] Source:Ultrasonics;83:222-235, 2018 Feb.
[Is] ISSN:1874-9968
[Cp] País de publicação:Netherlands
[La] Idioma:eng
[Ab] Resumo:The acoustic scattering of a plane wave by an elastic cylindrical shell is studied. A new approach is developed to predict the form function of an immersed cylindrical shell of the radius ratio b/a ('b' is the inner radius and 'a' is the outer radius). The prediction of the backscattered form function is investigated by a combined approach between fuzzy clustering algorithms and bio-inspired algorithms. Four famous fuzzy clustering algorithms: the fuzzy c-means (FCM), the Gustafson-Kessel algorithm (GK), the fuzzy c-regression model (FCRM) and the Gath-Geva algorithm (GG) are combined with particle swarm optimization and genetic algorithm. The symmetric and antisymmetric circumferential waves A, S , A , S and S are investigated in a reduced frequency (k a) range extends over 0.1
[Mh] Termos MeSH primário: Algoritmos
Biomimética/métodos
Lógica Fuzzy
Modelos Teóricos
Espalhamento de Radiação
Som
[Mh] Termos MeSH secundário: Simulação por Computador
Dose de Radiação
Radiometria/métodos
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Em] Mês de entrada:1802
[Cu] Atualização por classe:180212
[Lr] Data última revisão:
180212
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170715
[St] Status:MEDLINE



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