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Artigo IPEN-doc 27117 Correction factors for non-uniform large-area reference sources2020 - SILVA JÚNIOR, IREMAR A.; SIQUEIRA, PAULO de T.D.; NASCIMENTO, EDUARDO do; YORIYAZ, HELIO; SORDI, GIAN-MARIA A.A.; VIVOLO, VITOR; POTIENS, MARIA da P.A.Based on uniformity measurements of large-area reference sources used in calibration procedures of surface contamination monitors, an investigation was carried out to obtain a method that estimates the bias originated from surface source intensity distribution deviation from the ideal uniform distribution and corrects it. It relies on correcting the estimated instrument efficiency by applying correction factors driven from the uniformity distribution profiles of the sources used in calibration procedure. Simulations of the monitor calibration procedure are run for 2 distinct surface source distributions: the real and the ideally uniform distributions. Correction factors are driven from counting rate estimates obtained from each source representation. In order to evaluate adequacy of this proposition it was validated against a method proposed by the NPL in the Good Practices Guide No.14.Resumo IPEN-doc 27010 Tandem KAP meters calibration parameters by Monte Carlo Simulation using reference RQR radiation qualities2016 - POTIENS JUNIOR, ADEMAR; COSTA, NATHALIA; CORREA, EDUARDO; SANTOS, LUCAS; VIVOLO, VITOR; POTIENS, MARIA da P.The Kerma-area product quantity can be obtained by measurements carried out with a kerma-area product meter (KAP) with a plane-parallel transmission ionization chamber mounted on the X ray system. It is the integral of the air kerma over the area of the X ray beam in a plane perpendicular to the beam axis. This quantity has been important to establish the diagnostic reference levels (DRLs) all over the word. In this work the MCNP5 code was used to calculate the imparted energy in the air cavity of KAP meter and the spatial distribution of the air collision kerma in entrance plan of the KAP meter. From these data, the air kerma-area product (KAP) and the calibration coefficient for the KAP meter were calculated and compared with those obtained experimentally. The X-ray tube was easily modelled as well the complete tandem calibration set up was possible. The spectra of the diagnostic radiology RQR reference qualities measured were used as a source definition in the input card for the Monte Carlo simulation. The clinical KAP meter calibration coefficients were obtained experimentally and by Monte Carlo simulation. The differences between those values were about 2%, except for RQR 10 (5.45%). The uncertainties in Monte Carlo simulation were less than 0.5% in all cases and the FOM (Figure of Merit) was constant for a number of histories of 1 million.Capítulo IPEN-doc 25888 Determinação dos coeficientes de atenuação para feixes de raios X diagnóstico do PLA e do ABS impressos2018 - VALERIANO, C.; VENEZIANI, G.; JUNIOR, O.; VIVOLO, V.; SANTOS, W.S.; CAMPOS, L.L.Modelos 3D de estruturas anatômicas podem ser obtidos por meio de técnicas de imageamento médico (ressonância magnética e tomografia computadorizada). 70 Variando os materiais (por exemplo poliuretano e resina epóxi) utilizados em sua composição, é possível obter o contraste radiográfico ou a equivalência ao tecido desejado. A produção de objetos simuladores para pacientes específicos precisa preencher requisitos como a acurácia geométrica com a anatomia do individuo, a equivalência ao tecido, de modo que possam ser realizar medidas utilizáveis, e não ser susceptível aos efeitos da radiação. A utilização de impressoras 3D é uma forma rápida de construção de objetos complexos, dessa forma é justificável estudar a viabilidade da impressão 3D para desenvolver objetos simuladores. Baseado nesse cenário, o presente trabalho tem como objetivo avaliar a simulação desenvolvida, utilizando MCNP5, como ferramenta para a obtenção dos coeficientes de atenuação das placas feitas com material de impressora 3D.Resumo IPEN-doc 24579 Concentration and distribution evaluations of trace and rare earth element in sample sediments of the Billings and Guarapiranga reservoir systems2017 - TANCREDI, L.T.; SANTOS, L.C.; DINIZ, R.E.; VIVOLO, V.The Instruments Calibration Laboratory of IPEN calibrates annually about 75 instruments used by the radiation protection service at the nuclear reactor of IPEN. These instruments are used to personal and area monitoring and have different shapes and sizes, difficult their positioning in the calibration set up. They are calibrating usually with gamma radiation (137Cs, energy of about 660 keV). The gamma radiation system was automated recently in order to decrease the occupational dose of the technicians involved and accelerate all the calibration process. With the aim of increase the range of energy available to the calibration of the radiation protection instruments used at the nuclear reactor a new X radiation system was acquired by the LCI (YXLON SYSTEM, MODEL MGC41, 320 Kv). The ISO N series radiation protection radiation qualities will be established at this system. To improve the calibration set up, initially it was made the automation of two filter wheels to insert the appropriate thickness filter to each radiation quality. Each one of the 16 radiation qualities will receive a special filter (aluminum, lead or tin). The automation was made in a wheel filter and shutter (motor and pieces) of a former X radiation system (Rigaku Denki). Using the Arduino MEGA 2560 and a C++ programming it was possible to do the wheel rotation control; it chooses the adequate filtration and the shutter position through an interactive panel facilitating operation. The panel also informs the currently shutter position and the positioned filter. The preliminary tests show precision in selecting the position of the shutter, compared with the previously system (the Rigaku Denki system electro-mechanic) which selection was imprecise and often the shutter rotated instead of stopping at the desired position or stopped at an angle where the X-ray beam remained exposed. The new system also demonstrate to be faster to select the desired filtration because the software identifies the its position and rotates the wheel by the smallest path, choosing automatically right or left direction.Artigo IPEN-doc 24419 Comparação entre duas metodologias para correção da uniformidade de fontes extensas de referência2017 - SILVA JUNIOR, I.A.; SIQUEIRA, P.T.D.; NASCIMENTO, E.; VIVOLO, V.; POTIENS, M.P.A.São apresentados neste artigo os procedimentos para obtenção de fatores de correção de uniformidade de fontes ex- tensas de referência sugerida por duas metodologias distintas. A primeira metodologia é apresentada pelo Guia de Boas Práticas do Nº 14 do NPL, que oferece uma correção numérica e a segunda é uma correção que utiliza o código de transporte de radiação, MCNP5. Ambos os métodos resultam na proposição de valores de correções muito simila- res percentualmente, com desvio máximo de 0,24%.Artigo IPEN-doc 24418 Filtration influence in a constant potential X-ray machine peak voltage measurements2017 - SANTOS, L.R.; VIVOLO, V.; NAVARRO, M.V.T.; XAVIER, M.; POTIENS, M.P.A.This work shows the peak voltage measurements for several beam filtrations used in diagnostic radiology, using two types of non-invasive detectors; a voltage meter and a high-resolution spectrometer. The technique chosen for the voltage peak measurements with the spectrometer was the endpoint. The results were compared to the measured ones and showed good similarity to the nominal values. However the voltage meter detector used in this work pre-sented errors for heavier filtrations.Artigo IPEN-doc 23115 Characterization of a free air ionization chamber for low energy X-rays2016 - SILVA, NATALIA F. DA; XAVIER, M.; VIVOLO, V.; CALDAS, L.V.E.Free air ionization chambers are used by most primary metrology laboratories as primary standards of the quantities air kerma and exposure in X-ray beams. The free air ionization chamber for low energies of the Calibration Laboratory (LCI) of IPEN showed in a characterization test a problem in the set responsible for the variation of its sensitive volume. After a modification in the support of the micrometers used for the movement of the internal cylinder and the establishment of a new alignment system protocol, the tests were redone. The objective of this work was to present the results obtained in the new condition.Artigo IPEN-doc 23025 Mass attenuation coefficients of X-rays in different barite concrete used in radiation protection as shielding against ionizing radiation2017 - ALMEIDA JUNIOR, T.A.; NOGUEIRA, M.S.; VIVOLO, V.; POTIENS, M.P.A.; CAMPOS, L.L.The probability of a photon interacting in a particular way with a given material, per unit path length, is usually called the linear attenuation coefficient (μ), and it is of great importance in radiation shielding. Plates of barite concrete with different thickness were fabricated in order to determining their mass attenuation coefficients at different energies. The plates were irradiated with ISO X-ray beams (N60, N80, N110 and N150), generated by Pantak HF320 X-ray equipment, at the IPEN laboratory. The mass attenuation coefficients of barite concrete have been measured using X-ray attenuation for different thicknesses of barite concrete qualities of the ISO. The attenuator material issued from different regions of Brazil. The experimental procedure in this research was validated by comparison between the experimental measurements of mass attenuation coefficients and coefficients determined by the same atomic composition, using as a tool to XCOM. The highest value of (μ/ ρ) found experimentally was in the energy of 48 keV, in ISO 60 N quality, being 1.32( ± 0.49) for purple barite; 1.47( ± 0.41) for white barite and 1.75( ± 0.41) for cream barite. The determination of the chemical composition of the barite samples was of fundamental importance for the characterization of these materials. It can be seen that both calculated and measured data for the linear attenuation coefficients increase with the increasing materials density, as it is expected. It can be concluded that the photon attenuation coefficients depends on the photon energy and the materials density is the main contribution to the photon attenuation coefficients, which is important for radiation shielding.Artigo IPEN-doc 22882 Resposta de Microcubos de TLD-100TM a dois feixes de qualidade RQR32016 - NUNES, M.G.; VILLANI, D.; ALMEIDA, S.B.; VIVOLO, V.; YORIYAZ, H.; LOUIS, G.M.J.A resposta de microcubos de TLD-100TM a dois feixes de qualidade RQR 3, definida pela norma IEC-61267, é comparada para que a dependência da resposta do TLD-100TM com a energia efetiva do feixe de radiação X reportada na literatura seja avaliada nessas condições. A reprodutibilidade dos microcubos de TLD-100TM é avaliada através da resposta de um segundo conjunto de dosímetros, obtida em uma segunda leitora, ao feixe implementado no Laboratório de Calibração de Instrumentos do IPEN. A dependência da resposta com a energia efetiva ou o espectro do feixe não foi detectada e a reprodutibilidade das medidas é de 90,2%.Artigo IPEN-doc 22686 Comparação entre duas metodologias para correção da uniformidade de fontes extensas de referência2016 - SILVA JUNIOR, IREMAR A.; SIQUEIRA, PAULO de T.D.; NACIMENTO, EDUARDO; VIVOLO, VITOR; POTIENS, MARIA da P.A.São apresentados neste artigo os procedimentos para obtenção de fatores de correção de uniformidade de fontes extensas de referência sugeridos por duas metodologias distintas. A primeira metodologia é apresentada pelo Guia de Boas Práticas do Nº 14 do NPL, que oferece uma correção numérica e a segunda é uma correção que utiliza o código de transporte de radiação, MCNP5. Ambos os métodos resultam na proposição de valores de correções muito similares percentualmente, com desvio máximo de 0,24%.