WILLIAM DE SOUZA SANTOS
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Resumo IPEN-doc 27946 Monte Carlo approach for the determination of the angular dependence of an extrapolation chamber response2019 - POLO, IVON O.; CALDAS, LINDA V.E.; SANTOS, WILLIAM S.The angular dependence of an extrapolation chamber response is reported. The determination of the angular factors were carried out using the MCNP Monte Carlo Method. To determine the angular dependence, the PTW type 23392 extrapolation chamber of the Laboratory for Calibration of Instruments (LCI/IPEN) was simulated. The experiments were performed for the radiation fields of beta secondary standard BSS2 system sources. For the 90Sr/90Y source, the calibration distance of 11 cm without the beam flattening filter was used. For the 85Kr and 147Pm sources, the distances of 30 cm and 20 cm with the filter were used, respectively. The simulations were carried out by rotating the extrapolation chamber around the reference axis for angles between -90º and 90º, in steps of 5º. For the 90Sr/90Y source the angular dependence factor is greater than 1, predominating the dose build-up effect up to 60º and -60º, and the factor is less than 1 for the other angles, prevailing the absorption of beta particles. For the 85Kr and 147Pm sources, the angular dependence factor is less than 1 for all angles, predominating the absorption of beta particles too. The determined angular factors are in good agreement with the international report ISO 6980.Resumo IPEN-doc 26808 An extrapolation chamber for the establishment of a primary radiation standard in 85Kr and 147Pm beta radiation beams2019 - POLO, IVON O.; SANTOS, WILLIAM S.; CALDAS, LINDA V.E.Introduction At the Calibration Laboratory (LCI) of the IPEN/CNEN, studies are in development on the establishment of the Böhm extrapolation chamber model 23392 as a primary standard system for the dosimetry and calibration of beta-radiation sources and detectors. This chamber was already characterized at the LCI in 90Sr/90Y beams using two different entrance windows: one of aluminized Mylar and another of Hostaphan. This extrapolation chamber was characterized in 85Kr and 147Pm beams. All tests were carried out with the reference 90Sr /90Y source, for comparative purposes. Methods A Keithley model 6517B electrometer was used for the measurements. The utilized radiation sources are part of the Beta Secondary Standard BSS2. Moreover, the Monte Carlo code MCNP5 was used to determine the absorbed dose rates and to compare them with the experimentally determined dose rates and with those from the PTB calibration certifi cate. Results Saturation curves, ion collection effi ciency, ion recombination, polarity effect, response stability, real null depth, linearity of response, variation of response as a function of sourcedetector distance, extrapolation curves, correction factors and absorbed dose rates were obtained. The ion collection effi ciency was greater than 99%; the ionic recombination was less than 1%, and the polarity effect was greater than 1%. The stability of the response was lower than 0.15% for the repeatability test, and it was less than 0.36% for the reproducibility test. The difference between the experimental absorbed dose rates and those from the Monte Carlo model, compared to those from the calibration certifi cate, was less than 1.9% for all sources. Conclusions All results of the performed tests are within the limits of the international recommendations. The results for the 90Sr/90Y source were in the good agreement with previous works performed at LCI. These results are suitable for the establishment of a primary standard for beta radiation.Resumo IPEN-doc 26058 Cálculo de fator de conversão para dose absorvida em atividade de navegação utilizando o método Monte Carlo e um simulador antropomórfico virtual2019 - TAMURA, T.M.; SOUZA, R.E.; NEVES, L.P.; PERINI, A.P.; SANTOS, W.S.Resumo IPEN-doc 26011 Evaluation of polymer gels using Monte Carlo simulations2018 - SANTOS, W.S.; NEVES, L.P.; PERINI, A.P.; BELINATO, W.; CALDAS, L.V.E.Resumo IPEN-doc 23503 Dosimetria de pacientes adultos submetidos a exames de PET/CT2016 - BELINATO, W.; SANTOS, W.S.; CALDAS, L.V.E.; NEVES, L.P.; SOUZA, D.N.