LUCAS VERDI ANGELOCCI

LUCAS VERDI ANGELOCCI

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Avaliação do método produtivo de placas de epóxi com fósforo-32 para o tratamento do câncer espinhal e intracranial por braquiterapia
2022 - SILVA, J.T.; NOGUEIRA, B.R.; ANGELOCCI, L.V.; SOUZA, C.D.; TEODORO, L.E.; SOUZA, P.D.; RODRIGUES, B.T.; CORREIA, R.W.; SANTOS, H.N. dos; ZEITUNI, C.A.; ROSTELATO, M.E.
A braquiterapia é uma modalidade de radioterapia utilizada no tratamento do câncer. Nessa modalidade, a fonte radioativa é posiciona junto ao tumor ou bem próxima a ele. A dose de radiação é entregue de forma contínua em um período curto de tempo (fontes temporárias) ou em períodos mais longos durante todo o decaimento radioativo do material (fontes permanentes). A maior vantagem da braquiterapia, é o fato da fonte estar bem próxima ao tumor o que significa que a região alvo recebe a maior parte da dose protegendo os tecidos sadios adjacentes à região tumoral. Shtrombakh et. al. trabalharam com césio-137 e verificaram que o uso do epóxi para a imobilização de fontes radiativas ocorreu sem vazamento por dois anos de testes. Pesquisas realizadas nos Estados Unidos por Folkert et. al. mostraram que placas flexíveis incorporadas com fósforo-32 são alternativas para o tratamento de câncer do sistema nervoso central na fase intraoperatória. No presente trabalho foi avaliada a uniformidade da placa de resina epóxi a partir de uma metodologia desenvolvida no Laboratório de fontes para Braquiterapia do IPEN/CNEN- SP. Vários testes foram realizados para determinar o melhor molde para a fabricação da placa. Concluiu-se que o politetrafluoretileno (PTFE), que comercialmente é conhecido como teflon foi o que obteve melhor resultado, devido a facilidade para desenformar a fonte após o processo de cura da resina. As placas de epóxi foram produzidas a resina 2220 e catalisador 3154 (Avipol), à proporção de 2:1 (massa). Para simular o material radioativo, ácido clorídrico (HCl) equivalente a 5 % da massa total (resina + catalisador) é acrescentado. O processo de cura da resina epóxi foi durante 24 h sob temperatura ambiente. As espessuras das placas foram medidas chegando-se a um valor médio de 0,300 mm ± 0,070. As medidas foram efetuadas com micrômetro medindo-se 10 pontos de cada placa. As medidas de largura e comprimento não foram realizadas, pois esses parâmetros não influenciam na uniformidade da dose. Para que a distribuição da atividade do fósforo-32 fosse estipulada, uma simulação por Método de Monte Carlo utilizando o código MCNP foi realizada. A variação máxima de dose ao longo da placa, considerando uma espessura totalmente uniforme de 0,300 mm, resultou em < 0,5 % até 0,5 cm antes da borda. O resultado da simulação mostra que com uma placa de espessura uniforme, a tendência da distribuição de dose seja homogênea. Pautando-se nos resultados, as placas de polímero epóxi se mostram viáveis para o uso em braquiterapia, sendo que o próximo passo do trabalho será os testes com material radioativo, a avaliação por métodos dosimétricos físicos e computacionais.
Caracterização dosimétrica de uma nova fonte oftálmica de Irídio-192 usando métodos experimentais e simulações de Monte Carlo
2022 - ANGELOCCI, LUCAS V.
Aplicadores contendo sementes com núcleos radioativos são utilizados na braquiterapia oftálmica, para tratamento de câncer ocular, em um processo cirúrgico onde são suturados ao globo ocular do paciente por certo período de tempo, planejado para entregar a dose determinada ao alvo. Um novo modelo de semente para uso em braquiterapia oftálmica de produção nacional foi desenvolvido no Laboratório de Produção de Fontes para Radioterapia do Instituto de Pesquisas Energéticas e Nucleares, de forma que o custo final da semente será menor do que o custo de importação de um modelo internacional, ampliando sua possibilidade de uso. Para que a semente possa ser usada de forma segura na prática clínica, foi realizada uma caracterização dosimétrica da mesma seguindo os protocolos do Task Group 43 da American Association of Physicists in Medicine. Neste trabalho o cálculo dosimétrico foi realizado por três vias diferentes: dosimetria termoluminescente, com filmes radiocrômicos, e por simulações de Monte Carlo; comparando-as para validar os resultados, que se mostraram compatíveis para a maioria dos pontos analisados. Também foram realizadas análises para além daquelas propostas pelo protocolo, como comparações com outras fontes comerciais, avaliação do efeito no perfil de dose da variação de parâmetros de produção da fonte, e estimativas de dose no olho humano. Seus resultados foram discutidos com base na aplicação clínica pretendida, embasando com dados a discussão a respeito do Irídio-192 ser utilizado de forma viável e segura como radioisótopo para o tratamento em braquiterapia oftálmica.
New model for an epoxy-based brachytherapy source to be used in spinal cancer treatment
2021 - SILVA, JOSE T.; SOUZA, CARLA D. de; ANGELOCCI, LUCAS V.; ROSERO, WILMMER A.A.; NOGUEIRA, BEATRIZ R.; CORREIA, RUANYTO W.; ZEITUNI, CARLOS A.; ROSTELATO, MARIA E.C.M.
The present work described the cold fabrication of a P-32 radioactive source to be used in CNS cancer using epoxy resin. The epoxy plaque fabricated with Teflon mold presented better agreement. MCNP simulation evaluated the radiation dose. Special attention was given to factors that can impact dose distribution. Average dose was 16.44 ± 2.89% cGy/s. Differences of less than 0.01 cm in thickness within the plaque lead to differences of up to 12% in the dose rate.
Anisotropy function of a new 192-Ir brachytherapy source
2021 - ABREU, R.T.; ANGELOCCI, L.V.; NOGUEIRA, B.R.; SANTOS, H.N.; ZEITUNI, C.A.; ROSTELATO, M.E.C.M.
Brachytherapy is a type of radiotherapy that uses radioactive sources (seeds, wires, among others) close to the tumor. Is important to provide a detailed description of seed dosimetry, so only the tumor will be irradiated avoiding unnecessary dose on adjacent organs and structures. To evaluate the dosimetric parameter of the anisotropy function for a new brachytherapy source, this work proposes the use of microcube TLD-100 dosimeters to find the dose rate using the AAPM Task Group 43 protocol (TG-43). The anisotropy function represents dose distribution around the source and has a major role for characterization of a new iridium source being implemented in Brazil. The value of D(r,θ) was measured using Solid Water phantoms, r value being the distance from the geometric center of the source to the position of the dosimeter on the phantom, and θ being the angle formed between the longitudinal axis of the source and the line connecting the geometric center to the TLD. Monte Carlo calculations were performed to evaluate the anisotropy function to validate the experimental measurements. For each distance value (r), an anisotropy function was plotted (1.0, 2.0, 3.0, 4.0, 5.0, and 10.0 cm). The results obtained with Monte Carlo calculations agreed ±2% with the experimental values for r greater than 3.0 cm, so these results show a good distribution of dose around the seed considering the high energy of 192-Ir (average of 380 KeV) and encapsulation thickness.
Dose-rate constant and air-kerma strength evaluation of a new 125I brachytherapy source using Monte-Carlo
2021 - PRIMO, C.O.; ANGELOCCI, L.V.; KARAM JUNIOR, D.; ZEITUNI, C.A.; ROSTELATO, M.E.C.M.
Brachytherapy is a modality of radiotherapy which treats tumors using ionizing radiation with sources located close to the tumor. The sources can be produced from several radionuclides in various formats, such as Iodine-125 seeds and Iridium-192 wires. In order to produce a new Iodine-125 seed in IPEN/CNEN and ensure its quality, it is essential to describe the seed dosimetry, so when applied in a treatment the lowest possible dose to neighboring healthy tissues can be reached. The report by the AAPM’s Task Group 43 U1 is a document that indicates the dosimetry procedures in brachytherapy based on physical and geometrical parameters. In this study, dose-rate constant and air-kerma strength parameters were simulated using the Monte Carlo radiation transport code MCNP4C. The air-kerma strength is obtained from an ideal modeled seed, since its actual value should be measured for seeds individually in a specialized lab with a Wide-Angle Free-Air Chamber (WAFAC). Dose-rate constant and air-kerma strength are parameters that depends on intrinsic characteristics of the source, i.e. geometry, radionuclide, encapsulation, and together they define the dose-rate to the reference point. Radial dose function describes the dose fall-off with distance from the source. This study presents the values found for these parameters with associated statistical uncertainty, and is part of a larger project that aims the full dosimetry of this new seed model, including experimental measures.
Monte Carlo simulation to assess free space and end-weld thickness variation effects on dose rate for a new Ir-192 brachytherapy source
2021 - ANGELOCCI, LUCAS V.; SOUZA, CARLA D. de; PANTELIS, EVAGGELOS; NOGUEIRA, BEATRIZ R.; ZEITUNI, CARLOS A.; ROSTELATO, MARIA E.C.M.
A new Iridium-192 seed for brachytherapy is under development. Specific dose rate contribution by two different factors were evaluated: the effect from movement of the core in the free space within the seed and the effect of the end-weld thickness variation. Both were investigated through use of the Monte Carlo radiation transport code MCNP6 and an in-house routine programmed with MATLAB. Differences greater than 15% compared to results from the nominal seed were found near the source, indicating a significant dose variation.
New core configuration for the fabrication of 125I radioactive sources for cancer treatment
2020 - SOUZA, CARLA D. de; ZEITUNI, CARLOS A.; FEHER, ANSELMO; MOURA, JOÃO A.; COSTA, OSVALDO L. da; ANGELOCCI, LUCAS V.; ROSTELATO, MARIA E.C.M.
In order to provide prostate brachytherapy treatment for more Brazilian men, IPEN is building a laboratory for the manufacture of radioactive sources. The new methodology for the production of iodine-125 seeds with yield 71.7% ± 5.3%. Points of importance were evaluated/discussed: photo-sensibility, reaction vial type, the substitution for iodine-131, pH, and solution volume. The surface was analyzed by FTIR and EDS. At the end, a Monte Carlo-MCNP6 simulation was performed to evaluate the TG-43 parameters.
End-weld thickness variation effects on dose rate for a new ir-192 brachytherapy source
2019 - ANGELOCCI, LUCAS V.; NOGUEIRA, BEATRIZ R.; ABREU, RODRIGO T.; ZEITUNI, CARLOS A.; ROSTELATO, MARIA E.C.M.
Brachytherapy is a form of radiation therapy that uses small sealed sources close to the tumor to deliver a high dose to target while keeping dose on neighboring healthy tissues as low as possible. A wide variety of radionuclides and different sources are available for brachytherapy, each with his own unique geometry. The Laboratory of Sources Production for Radiotherapy (IPEN/CNEN) developed a new Ir-192 seed for eye tumor treatment that is currently under dosimetric definition. This work is part of a larger project that aims the full dosimetry of this new source, but rather than calculate the usual parameters proposed by the American Association of Physicists in Medicine, the specific contribution to the dose rate of a usually not considered factor was investigated under a statistical approach: end-weld thickness variation, which is important due to this source being welded by an in-house method. Its effects were investigated using the Monte Carlo radiation transport code MCNP4C and an in-house routine programmed with MATLAB® to analyze the data. Final results are presented as a mean value for dose rate at different points of interest and their associated standard deviations. The results are discussed based on the influence of said parameter on different points around the source.
Anisotropy function of a new 192-Ir brachytherapy source
2019 - ABREU, RODRIGO T.; ANGELOCCI, LUCAS V.; NOGUEIRA, BEATRIZ R.; SANTOS, HAMONA N. dos; ZEITUNI, CARLOS A.; ROSTELATO, MARIA E.C.M.
Brachytherapy is a type of radiotherapy that uses radioactive sources (seeds, wires, among others) close to the tumor. Is important to provide a detailed description of seed dosimetry, so only the tumor will be irradiated avoiding unnecessary dose on adjacent organs and structures. To evaluate the dosimetric parameter of the anisotropy function for a new brachytherapy source, this work proposes the use of microcube TLD-100 dosimeters to find the dose rate using the AAPM Task Group 43 protocol (TG-43). The anisotropy function represents dose distribution around the source and has a major role for characterization of a new iridium source being implemented in Brazil. The value of D(r,θ) was measured using Solid Water phantoms, r value being the distance from the geometric center of the source to the position of the dosimeter on the phantom, and θ being the angle formed between the longitudinal axis of the source and the line connecting the geometric center to the TLD. Monte Carlo calculations were performed to evaluate the anisotropy function to validate the experimental measurements. For each distance value (r), an anisotropy function was plotted (1.0, 2.0, 3.0, 4.0, 5.0, and 10.0 cm). The results obtained with Monte Carlo calculations agreed ±2% with the experimental values for r greater than 3.0 cm, so these results show a good distribution of dose around the seed considering the high energy of 192-Ir (average of 380 KeV) and encapsulation thickness.
Dose-rate constant and air-kerma strength evaluation of a new 125-I brachytherapy source using Monte-Carlo
2019 - PRIMO, CAMILA de O.; ANGELOCCI, LUCAS V.; KARAM JUNIOR, DIB; ZEITUNI, CARLOS A.; ROSTELATO, MARIA E.C.M.
Brachytherapy is a modality of radiotherapy which treats tumors using ionizing radiation with sources located close to the tumor. The sources can be produced from several radionuclides in various formats, such as Iodine-125 seeds and Iridium-192 wires. In order to produce a new Iodine-125 seed in IPEN/CNEN and ensure its quality, it is essential to describe the dosimetry of the seed, so when applied in a treatment the lowest possible dose to neighboring healthy tissues can be reached. The report by the AAPM’s Task Group 43 U1 is a document that indicates the dosimetry procedures in brachytherapy based on physical and geometrical parameters. In this study, dose-rate constant and air-kerma strength parameters were simulated using the Monte Carlo method radiation transport code MCNP4C. The air-kerma strength is obtained from an ideal modeled seed, since its actual value should be measured for seeds individually in a specialized lab with a Wide-Angle Free-Air Chamber (WAFAC). Dose-rate constant and air-kerma strength are parameters that depends on intrinsic characteristics of the source, i.e. geometry, radionuclide, encapsulation, and together they define the dose-rate to the reference point, defined as the dose-rate to a point 1 cm away from the geometric center of the source, in its transverse plane. This study presents the values found for these parameters with associated statistical uncertainty, and is part of a larger project that aims the full dosimetry of this new seed model, including experimental measures.