PAULO DE TARSO DALLEDONE SIQUEIRA

PAULO DE TARSO DALLEDONE SIQUEIRA

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Thermal neutron dose measurements using TLD-100 detectors in the IPEN/MB-01 reactor core
2024 - CAVALIERI, TASSIO A.; SIQUEIRA, PAULO de T.D.; SHORTO, JULIAN M.B.; YORIYAZ, HELIO
Considerable experimental effort has been aimed at uncovering a reliable way to perform a dosimetric assessment in mixed radiation fields. In fields composed by gammas and neutrons, TLD dosimeters are usually applied to execute such measurements, although there is no consensus on the most favorable strategy to employ them. In this context, TLD-100 measurements within two different core configurations of the IPEN/MB-01 research reactor and Monte Carlo simulations have been used to investigate the behavior of those detectors in multiple mixed radiation fields, deriving a methodology to evaluate the dose deposition in the dosimeter by different gamma and neutron energy spectra and intensities. A surprising outcome is the linear neutron dose response shown by TLD-100 even irradiated by so distinct irradiation fields.
Princípios e aplicações da terapia por captura de nêutrons por boro
2019 - SIQUEIRA, PAULO T.D.; YORIYAZ, HELIO; SHORTO, JULIAN M.B.; CAVALIERI, TASSIO A.
A terapia por captura de nêutrons (neutron capture therapy — NCT) é uma técnica radioterápica bimodal com princípios de funcionamento muito vantajosos para o tratamento de cânceres difusos. Contudo, apesar dessa vantagem conceitual e de sua primeira proposição já exceder 80 anos, essa técnica ainda não se encontra consolidada na comunidade clínica internacional como proposta terapêutica. Esse insucesso em seu estabelecimento não tem impedido que diversos grupos de pesquisa de diversos países do mundo invistam tempo e recursos em seu desenvolvimento. Neste texto apresentamos brevemente um histórico da NCT e dos principais desafios enfrentados pelos diversos grupos de pesquisas, uma comunidade de entusiastas da técnica, no seu desenvolvimento e na consolidação terapêutica da sua vertente mais estudada, a boron neutron capture therapy (BNCT). É apresentado também um resumo dos principais resultados alcançados com a técnica, além de um breve relato dos estudos realizados na instalação experimental de BNCT no Brasil.
Design, fabrication and modeling of an AmBe neutron irradiator for TLD screening for neutron dose measurement in mixed radiation fields
2019 - CAVALIERI, TASSIO A.; SIQUEIRA, PAULO T.D.; SHORTO, JULIAN M.B.; GENEZINI, FREDERICO A.; YORIYAZ, HELIO
TLDs dosimeters are frequently presented as a viable choice for dosimetric studies when dealing with mixed neutron-gamma radiation fields. However, this choice is not without some drawbacks, because not only TLD response is highly dependent on particle type but also on neutron energy spectrum. Therefore, a correct screening and calibration of the dosimeter are required, and a simple shift from gamma screening methodology for mixed field is not suitable. This paper presents the design, fabrication and tests of an irradiator for TLD screening for neutron dose measurement using an AmBe source and polyethylene as moderator material. The design of the irradiator was conducted through Monte Carlo simulations using the MCNP5 code. The experimental validation and tests were performed using Indium activation foils and TLD 600 dosimeters. The manufactured irradiator demonstrated to be suitable for TLD screening under neutron source radiation field, offering very good homogeneity conditions in the radiation field so to guarantee same radiation dose delivered to the TLDs.
Reactor IPEN/MB-01 dosimetry using TLDs
2017 - CAVALIERI, TASSIO A.; SIQUEIRA, PAULO T.D.; YORIYAZ, HELIO
This paper is a preliminary study on the use of reactor IPEN/MB-01 as standard radiation source for mixed field dosimetry studies. As a first step on this attempt, simulations and experiments, evaluating the neutron and gamma field distributions, were performed and compared. TLDs are widely employed in dose measurements and the TLD 100 / TLD 700 pair conforms with ICRU recommendations for mixed field dosimetry. In this study, TLD irradiations were performed in the IPEN/MB-01 nuclear reactor. IPEN/MB-01 reactor is zero power reactor widely used to perform reactor physics experiments. Its neutron flux distribution is well known for a variety of reactor core configurations. However, the photon fluxes are unknown. A series of experiments with TLD 100 and TLD 700 were performed for two different core configurations (rectangular and cylindrical with a central flux trap). Simulations with MCNP5 for these two configurations were also done, and neutron and gamma fluxes distributions along the core were computed. The responses of TLD 100 and TLD 700 were compared with simulated fluxes and showing a good agreement between them. This paper presents the results of the experiments done so far given the status of the study under way in order to couple IPEN/MB-01 and TLD 100 / 700 pair into a mixed field calibration methodology.
Study of energetic dependence of LiF TLDs for photons
2015 - CAVALIERI, TASSIO A.; ANTUNES, PAULA C.G.; PAIVA, FABIO; BRANCO, ISABELA S.; SENA, MICHELLE K.S.; SIQUEIRA, PAULO T.D.; YORIYAZ, HELIO
Comparing the responses of TLD 100, TLD 600, TLD 700 and TLD 400 in mixed neutron-gamma fields
2015 - PAIVA, FABIO; SIQUEIRA, PAULO T.D.; CAVALIERI, TASSIO A.
Evaluation of TLD dose response compared to MCNO-5 simulation of diagnostic X ray equipment - radiation diagnostic image
2014 - GIAROLA, RODRIGO S.; CAVALIERI, TASSIO A.; PAIVA, FABIO de; FERNANDES, MARCO A.R.; SIQUEIRA, PAULO de T.D.; VIVOLO, VITOR; YORIYAZ, HELIO
Differences TLD 600 and TLD 700 glow curves derived from distict mixed gamma/neutron field irradiations
2013 - CAVALIERI, TASSIO A.; CASTRO, VINICIUS A.; SIQUEIRA, PAULO T.D.
MCNP study the BFsub(3) detection efficiency
2011 - CASTRO, VINICIUS A.; CAVALIERI, TASSIO A.; SIQUEIRA, PAULO T.D.; FEDORENKO, GIULIANA G.; COELHO, PAULO R.P.; MADI FILHO, TUFIC