LUCAS VERDI ANGELOCCI

LUCAS VERDI ANGELOCCI

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Thermoluminescent dosimetry planning through MNCP
2023 - NOGUEIRA, THUANY; TALACIMON, CRISTHIAN; TEODORO, LARA; RIGO, MARIA; RODRIGUES, PRISCILA; ANGELOCCI, LUCAS; NOVAES, HAMONA; ZEITUNI, CARLOS; ROSTELATO, MARIA
Dosimetric approach of Au-198 nanoparticles with radiochromic film
2023 - RIGO, MARIA; ANGELOCCI, LUCAS; RODRIGUES, PRISCILA; TALACIMON, CRISTHIAN; MEDEIROS, ILCA; TEODORO, LARA; NOGUEIRA, THUANY; ROSERO, WILMMER; ZEITUNI, CARLOS; ROSTELATO, MARIA
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.
Development of a new material to encapsulate phosphorus-32 for use in brachytherapy
2022 - TEODORO, LARA E.H.; TALACIMON, CRISTHIAN F.; ROSERO, WILMMER A.A.; RIGO, MARIA E.Z.; RODRIGUES, PRISCILA S.; NOGUEIRA, THUANY C.; ANGELOCCI, LUCAS V.; ROSTELATO, MARIA E.C.M.
The term cancer refers to a set of malignant diseases that have in common the disordered growth of mutated cells, which can invade adjacent tissues or distant organs[1]. In 2020, cancer of the central nervous system (CNS) represented 1.6% of all new malignant tumor cases in the world, and about 2.5% of all new cancer deaths[2]. A promising radioactive source for use in intracavitary brachytherapy is phosphorus-32. This source has been prominent as a minimally invasive treatment for craniopharyngiomas and in the treatment of metastatic bone diseases in general[3]. To encapsulate phosphorus-32 and make it a viable radioactive source for use in medicine, some methods have emerged. In this work, we are developing a fabric soaked in industrial latex for this purpose, as this source comes in the form of orthophosphoric acid in aqueous solution and as industrial latex is soluble in water. Tests carried out so far show that the material supports orthophosphoric acid while is still malleable, which is essential for treating spinal cancer.
Homogeneity evaluation of phosphorus-32 epoxy plaques to be used in the treatment of spinal and intracranial cancer by brachytherapy
2021 - SILVA, JOSE T. da; SOUZA, CARLA D. de; NOGUEIRA, BEATRIZ R.; ANGELOCCI, LUCAS V.; ZEITUNI, CARLOS A.; ROSTELATO, MARIA E.C.M.
In Brachytherapy, radioactive source is positioned close to the tumor. The most important advantage is that the target region receives most of the dose, protecting the healthy tissues adjacent to the tumor region. In order to use these sources, a high dosimetric uniformity must be achieved, so a homogeneous dose delivery can be delivered to the target. In the present work, the consistency of the epoxy resin plate was evaluated using a methodology developed in the laboratory for the production of radiotherapy sources at IPEN / CNEN - SP. Several tests were carried out to determine the best mold for the source manufacture. It was concluded that polytetrafluoroethylene (PTFE), which is commercially known as teflon, obtained the best result, due to the ease unmold of the source after the resin curing process. The epoxy plaques were produced with resin 2220 and catalyst 3154 (Avipol), at a 2:1 mass ratio. To simulate the radioactive material, hydrochloric acid (HCl) equivalent to 5% of the total mass (resin + catalyst) is added. The epoxy resin cured for 24 h at room temperature. The thickness of the plaques was measured reaching an average value of 0.300 mm ± 0.070. The measurements were made with a micrometer, measuring 10 points of each plaque. The measures of width and length were not performed, as these parameters do not influence the uniformity of the dose. In order for the distribution of phosphorus-32 activity to be stipulated, a Monte Carlo Simulation using the MCNP code was performed. The maximum dose variation along the plaque, considering a totally uniform thickness of 0.300 mm, resulted in <0.5% up to 0.5 cm before the edge. The result of the simulation shows that with a uniformly thick plaque, the dose distribution trend is homogeneous. Based on the results, the epoxy polymer plaques are shown to be viable for use in brachytherapy, and the next step of the work will be the tests with radioactive material.
Assessing Ir-192 as an alternative to I-125 in ophthalmic treatment
2020 - ANGELOCCI, L.; NOGUEIRA, B.R.; SOUZA, C.D. de; ZEITUNI, C.A.; ROSTELATO, M.E.C.M.
Purpose or Objective: Brachytherapy sources for ocular melanoma usually contain Co-60, I-125, Pd-103 or Ru/Rh-106 as radionuclides. Ir-192 is not a preconized radioactive material for this purpose, although it is used for other brachytherapy applications. Higher mean energy from Ir-192 emission (ca. 380 keV) may be a reason for the preference of I-125 (35 keV) or Pd-103 (21 keV) over it, since low penetration is desired on the small structures of the human eye. This is not, however, an excluding criterion, considering Co-60 and Ru/Rh-106 have even higher mean energies. The demand in Brazil for lower-cost seeds to treat ocular melanoma lead to the development of an Ir-192 seed to make treatment more accessible, but since it is not used as an ophthalmic brachytherapy source, before its dosimetry is considered, one should care about the possibility of using it over more stablished materials. Considering this, the aim of this work is to assess the possibility of using Ir-192 seeds as ophthalmic brachytherapy sources by comparing some dosimetric parameters of a new seed model with the most stablished I-125 seed in literature, OncoSeed 6711. Material and Methods: As an initial study on the topic, this work relies only on Monte-Carlo simulations using MCNP4C transport code. Parameters analyzed are air-kerma strength, dose-rate constant and depth-dose curve, attention given to points within the human eye dimensions. The medium considered was homogeneous water, as it is a good approximation to the eye tissues in terms of composition and density and allows for future comparisons with TG-43 based calculations. OncoSeed 6711 is not produced anymore, but its long term as the reference source for dosimetry was considered. A 20 mm COMS ophthalmic applicator was also modeled and considered to be fully loaded with each seed model to compare the same parameters at a realistically clinical approach. Results: As expected, due to the higher energy of the Ir-192 emission spectrum, dose fall-off on the transversal axis of the seeds is less pronounced for the new seed model. The steeper dose gradient for I-125 is also visible on the doserate constant value. The effect of using a COMS applicator only strengthens this characteristic. Depth-dose curves were calculated up to the distance of 5 cm, both for a single seed and for an applicator fully loaded with 24 seeds. All the eye components relevant for dosimetry are located within this range, like the cells of the crystallin and the optical nerve. Conclusion: If one expects to use Ir-192 as an alternative to I-125 in ophthalmic cancer treatment, at least the dosimetry following TG-43 protocol should be carried with utmost attention, as undesirable dose to healthy nearby tissues is unavoidable. Crafting a different applicator most suited for this radionuclide is a possibility that can be taken into account. Another recommendation is to go beyond TG-43 water-based protocol and actually estimate dose to relevant eye components.
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.