Half Value Layer
Mostrando 1-12 de 25 artigos, teses e dissertações.
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1. Gamma Ray and FTIR Studies in Zinc Doped Lead Borate Glasses for Radiation Shielding Application
Gamma ray shielding properties of borate glass samples containing oxides of lead and zinc are prepared by melt and quench technique and evaluated theoretically using XCOM computer software for gamma ray shielding properties. However, gamma ray shielding properties are discussed in terms of various calculated parameters such as half value layer, mean free pat
Mat. Res.. Publicado em: 14/11/2018
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2. Study on patient dosimetry and image quality in digital mammography
Abstract Introduction Digital mammography present many advantages in comparison to conventional mammography, such as high dynamic range and the post-processing of acquired images. One problem is that protocols may not be optimized, resulting in higher absorbed doses to patients. The objective of this work is to evaluate image quality and to estimate mean gl
Res. Biomed. Eng.. Publicado em: 2017-06
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3. Comparative Study of Radiation Shielding Parameters for Bismuth Borate Glasses
Melt and quench technique was used for the preparation of glassy samples of the composition x Bi2O3-(1-x) B2O3 where x= .05 to .040. XCOM computer program is used for the evaluation of gamma-ray shielding parameters of the prepared glass samples. Further the values of mass attenuation coefficients, effective atomic number and half value layer for the glassy
Mat. Res.. Publicado em: 31/05/2016
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4. Análise dos procedimentos e critérios de implantação de feixes de raios X de referência ISO 4037 em baixas energias
According to the radiological protection principles, practices involving ionizing radiation must be planned and carried out under the guarantee that the values of individual doses, the number of people exposed to radiation and the probability of accidental exposures are as low as reasonably achievable. Therefore, radiation dosimetry is required to be done wi
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 09/08/2012
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5. Determination of dosimetric quantities of interest in Mammography using thermoluminescent detectors. / Determinação de grandezas dosimétricas de interesse em mamografia usando detectores termoluminescentes
National and international health organizations such as the Brazilian Ministry of Health, through its Secretary of Health Surveillance establishes in the publication Nº 453/98 that in all mammographic equipments must be evaluated the entrance-skin dose through the readings of an ionization chamber-electrometer system corrected by the backscatter factor, amo
Publicado em: 2010
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6. Transmissão e fluência de fótons na área de radiodiagnóstico para diferentes configurações de feixes e blindagens
Neste trabalho foi realizado um estudo da influencia das composições dos materiais de blindagem e variações nos espectros emitidos por equipamentos de raios X através da utilização de um programa computacional que utiliza a técnica de Monte Carlo. Foi determinada a fluência de fótons depois das blindagens, com geometrias realísticas de feixe prim�
Publicado em: 2010
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7. Development of a calibration methodology for instruments used to interventional radiology quality control / Desenvolvimento de uma metodologia para a calibração de instrumentos de medida utilizados no controle da qualidade em radiodiagnóstico intervencional
Interventional radiology is the technique where X radiation images are used as a tool in the conduction of diagnostic or/and therapeutic procedures. The exposition times are long for both procedures, diagnostic and therapeutic, may cause serious injuries in the patient, and also contribute to the dose of the clinical staff. In Brazil there are not yet well e
Publicado em: 2009
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8. Desenvolvimento de um sistema computacional para utilização em procedimentos de controle de qualidade em equipamentos mamográficos / Development of a computational system for quality control procedures on mammographic equipment
The present work consists on developing a computational methodology to provide information regarding to mammographic equipment quality evaluation. This investigation have taken into account, beyond the required operational parameters, such as kVp, electrical current, focal point, dose, exposition time, half-value layer, the influence of the film digitizer ut
Publicado em: 2007
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9. Caracterização e dosimetria de feixes de raios-x de 100 e 140kVp usados em radioterapia
Radiotherapy is the modality used in the treatment of malignant neoplasias that aims the deposition of a controlled amount of ionizing radiation in a limited area of the patient body. In order to provide a well-known and as accurate as possible absorbed dose for controlling a lesion, all characteristics of the treatment radiation beam must be known. For this
Publicado em: 2006
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10. Construction and the validation tests of an electronic device able to measure the half value layer in diagnostic X-ray beams / Construção de um dispositivo eletronico para determinação de camada semi-condutora em feixe de raios-x diagnostico
This work describes the construction and the validation tests of an electronic device able to measure the half value layer in diagnostic X-ray beams. The device utilizes a transducer assembled with three sensors using the photoluminescence of the organic scintillator anthracene. The light signal, proportional to the incident radiation, reaches three photo re
Publicado em: 2005
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11. Individual monitoring for external exposures: experimentation and simulation with Monte Carlo Method / Monitoração individual externa: experimentos e simulações com o método de Monte Carlo
In this work, we have evaluated the possibility of applying the Monte Carlo simulation technique in photon dosimetry of external individual monitoring. The GEANT4 toolkit was employed to simulate experiments with radiation monitors containing TLD-100 and CaF2:NaCl thermoluminescent detectors. As a first step, X ray spectra were generated impinging electrons
Publicado em: 2005
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12. Quality evaluation in diagnostic radiology: computer simulation for half-value layer investigation / Avaliação de qualidade em radiodiagnóstico: simulação computacional para investigação da camada semi-redutora
A camada semi-redutora (CSR), definida como a espessura de um material absorvedor que colocado sob um feixe de raios-X reduz sua intensidade à metade, é um parâmetro que deve ser avaliado periodicamente nos programas de garantia de qualidade em radiologia médica, pois fornece informações a respeito do desempenho do feixe radiográfico produzido pelo ap
Publicado em: 1999