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Autor: Bianca Lamarca da Cruz

Resumo: The Institute of Nuclear Engineering has a radiopharmaceutical production sector that manufactures ultrapure Iodine-123 for medical applications, using the CV-28 cyclotron accelerator. The particle beam is driven to the target sample to be irradiated, that is placed in a own concret cave placed 15 m away from CV-28. This target cave, where a xenon-124 gas target is positioned, reaches the dose level limits set out by the Brazilian National Nuclear Energy Commission Standard 3.01[1] in its surrounding ar

Autor: Victor Rocha Carvalho, Walsan Wagner Pereira, Simone da Silva Fernandes, Karla Cristina de Souza Patrão, Evaldo Simões da Fonseca

Resumo: A medição do espectro de nêutrons foi realizada através da metodologia das multiesferas de Bonner, que consiste em usar um detector de nêutrons térmicos de 6LiI(Eu). As contagens de nêutrons das fontes isotópicas 241AmB, 241AmLi e 241AmF foram realizadas com seis diferentes moderadores esféricos em torno do detector, e por meio dessas medições foi obtido o espectro de nêutrons através do software desenvolvido pelo laboratório de metrologia de nêutrons do Instituto de Radioproteção e Dosimetria – LN/IRD, NeutraLN que utiliza a técnica de redes neurais. A importância da caracterização do espectro em energia das fontes citadas é fundamental para a ampliação da capacidade de medição do LN/IRD, apesar das intensidades de emissão dessas fontes serem pequenas quando comparadas a outras fontes utilizadas para calibração de dispositivos pela instalação, tais como: 241AmBe e 252Cf. Os valores médios dos equivalentes de dose ambiente dessas fontes isotópicas também são apresentados.

Autor: Beatriz Silva de Assis, Leonardo de Castro Pacífico, José Guilherme Pereira Peixoto

Resumo: The radiation dose to which an Occupationally Exposed Individual (OEI) is subjected is obtained by the operational quantity of the ambient dose equivalent (H*(10) for strongly penetrating radiation). This quantity makes it possible to estimate the dose received by the OEI during the time spent at its workplace. Thus, to automate the counting of this time and improve the accuracy of the calculation of the received dose, it is proposed to build a smart system based on Arduino with a PIR presence sensor. In that sense, a work routine in a radiopharmacy was analyzed, where the times and dates of entry and exit of the OEI in this place during their work period, for 15 days, were evaluated. A total of 368 accumulated hours were acquired, of which 96 hours were OEI’s exposure to ionizing radiation inside the radiopharmacy, where a radiometric survey was carried out to obtain the average ambient dose equivalent rate in the center of the room. From this, a calculation was made to obtain the total dose received by the OEI. This showed that the presence of a smart system using Arduino was promising in estimating the ambient dose equivalent, which favors the creation of future smart system projects aimed at Metrology 4.0.

Autor: João Henrique Hamann da Silva, José Guilherme Pereira Peixoto, Otávio Riani de Oliveira

Resumo: Dosimeters gels, in particular polymerics gels, are used to evaluate threedimensional dose distribution in radiotherapy treatments. Thus, polymer gel dosimeters allow a volumetric and not point visualization, as occurs with an ionization chamber. Therefore, this work consisted in evaluating the planning of cancer treatment for the head region using a phantom of the anatomical area filled with gels. Next, tomographic images (computed tomography scan) were generated, which were used for virtual planning and mathematically evaluated. After irradiating the phantom set in a medical linear accelerator, the next step was to submit the simulator to magnetic resonance (MRI) where images were mathematically postprocessed. Thus, uncertainties associated at this stage of the process were evaluated.

Autor: Monaliza de Oliveira Almeida, Matheus Rabello do Nascimento, Carlos Henrique Simões de Sousa, José Guilherme Pereira Peixoto

Resumo: The MC method makes it possible to assess the dose in diagnostic procedures and in studies of the quality of medical images. Half Value Layer can be defined as the thickness of absorbing material needed to reduce the intensity of the X-ray beam to 50% of the initial value, under conditions of good geometry. In view of this, it is possible to simulate, through the MC Method, situations and find values close to reality. The objective of this work is to investigate the use of the Monte Carlo simulation code EGSncr to calculate the Half Value Layers of shields aimed at Radiological Protection, stating its real need and estimating the thickness of the materials to be used in the shields. To carry out the simulations, 1 (one) Desktop computer with Linux Mint 20.1 Cinnamon operating system, Intel© Core™2 Duo Processor E8400 CPU @ 3.00GHz × 2, 3.7 GiB Memory, 160.1 GB Hard Disks; Monte Carlo EGSncr code for the construction of the simulations, where 15 cm diameter barium concrete discs were created, with thicknesses of 0.5, 1.0, 1.5 and 2.5, where x-ray beams of 70, 120 and 140 KeV. Thus, according to the results found, we can state that there is a lot of energy scattering, and that there is the necessary shielding to be able to have protection against the x-ray beams, confirming the effectiveness of the protection of the barium mixture, as shown. The simulation’s easing graphs show that the values are in line with what was expected. Therefore, we can state that the Monte Carlo simulation program EGSnrc is a reliable and efficient tool for experiments with x-ray beams.

Autor: JEOVANA SANTOS FERREIRA, ERIC MATOS MACEDO, IGOR FERNANDO MADESTO GARCIA, DANIELE ANDRADE CORRÊA DE JESUS, MARCUS VINÍCIUS TEIXEIRA NAVARRO

Resumo: Na mamografia, exame de referência para detecção de alterações mínimas nos tecidos moles da mama que possuem densidades próximas, a dose glandular média (DGM) avalia a exposição da mama à radiação, e é a grandeza que melhor expressa o risco carcinogênico induzido pela radiação ionizante na mama sendo avaliada utilizando-se dosímetro calibrado e coeficientes de conversão tabelados derivados da determinação da camada semirredutora (CSR) e da glandularidade da mama. Este trabalho teve como objetivo implantar no LABPROSAUD/IFBA a base metrológica para calibração de medidores de radiação com aplicação em mamografia, para as séries de qualidades de radiação com combinação anodo de Tungstênio e filtro de Paládio, Prata e Ródio nas tensões de 25, 28, 30 e 35 kV, de acordo com os parâmetros técnicos recomendados pela IEC 61267 e pelo TRS457, seguindo referências do PTB. Os resultados obtidos de CSR foram satisfatórios para caracterização das qualidades bem como a taxa de kerma no ar e kerma de referência apresentados para as séries de qualidades de radiação W-Ag, W-Pd e W-Rh. Sendo implantar estas séries aplicadas a mamografia, desenvolvendo um processo que assegura rastreabilidade metrológica e ampliação do escopo do cenário brasileiro de calibração.

Autor: Henrique Viccari Cabete, Rafael Eidi Goto, Orlando Rodrigues Junior, Renato Semmler

Resumo: Após a atualização da Instrução Normativa IN 92 que dispõe sobre requisitos sanitários para a garantia da qualidade e da segurança de sistemas de mamografia em 27 de maio de 2021, inseriu-se um novo parâmetro para a avaliação das doses típicas, a dose glandular média (DGM). Diante deste contexto, objetivou-se verificar a influência dos detectores e de outros fatores na estimativa da DGM. Verificou-se que o espalhamento da radiação na bandeja de compressão mamográfica contribuiu para um aumento nos valores estimados entre 3,3 e 4,9%. Quando reduzido o espalhamento, os resultados das estimativas para os quatro detectores usados na avaliação tiveram uma diferença de no máximo de 7,1% e 2,1% quando comparados apenas detectores específicos para a modalidade de mamografia. Verificou-se que o retroespalhamento não contribuiu de forma significativa para a alteração dos resultados.

Autor: Eric Matos Macedo, Matheus Rebello Nascimento, Leonardo Pacífico, Igor F M Garcia, Jeovana Ferreira, Walmir Belinato, William S Santos, Marcus Navarro, José Guilherme P Peixoto

Resumo: The digital revolution is a reality. Many areas of industry, services as well as others applications fields, are migrating part of their jobs – even the totality – to the digital environment. Ionizing radiation metrology can not be out of this world. For this objective, the creation of a virtual environment from the physical systems of radiation meter calibration has been proposed. The methodology tools used consist of describing all the key elements of this laboratory in Monte Carlo, using EGSnrc and egs_phd application, to simulate them and to validate the system comparing it with experimental data in the same condition. In this context, the N60 radiation quality, from ISO 4037-1, was chosen for this purpose. An AMPTEK XR-100T CdTe was used on spectrometry, and the spectra were corrected based on the Stripping method. The results showed a good agreement between experimental and simulated spectra, with a difference in their mean energy of 1.4% within the ±5% tolerance range required on ISO 4037-1:1996. After being corrected, both had mean energy of 47.2 keV and a spectral resolution of 33%, which complies with the requirements to produce the ISO N60 reference beam. This indicates that, at first analysis, the virtual system can be exposed to new metrological tests.

Autor: Solano Rigotti Caiano, Vanderlei Cruz, Márcio Bottaro, Marco Aurélio Lisboa Leite, Hélio Massaharu Murata, Daniel Alexandre Baptista Bonifácio

Resumo: A fotomultiplicadora de silício (SiPM – “Silicon Photomultiplier”) tornou-se um dispositivo importante capaz de detectar a radiação X e gama. Uma desvantagem dessa tecnologia é a dependência de temperatura que o material semicondutor possui. A caracterização em energia da SiPM, possibilita mensurar parâmetros importantes sobre o detector. A SiPM acoplada ao cristal cintilador, compõe o aparato experimental e as medidas são realizadas através de um osciloscópio. Os resultados apresentados demonstram o comportamento esperado da SiPM sem a influência do cristal cintilador. Com a análise dos espectros em energia, é possível desenvolver um método de controle capaz de minimizar a influência da dependência da temperatura.

Autor: Matheus Rebello do Nascimento, Josilene Cerqueira Santos, Eric Matos Macedo, Leonardo de Castro Pacífico, José Guilherme Pereira Peixoto

Resumo: X-ray detection systems require a deep analysis of their particularities and operational limitation. In that sense, measurements with solid-state detectors can present considerable distortions due to the interaction between the photons and the detector. Therefore, to overcome these distortions, the Stripping methodology correction is extensively discussed in this paper. To evaluate the performance of this methodology, the ISO 4037-1 narrow-spectrum series from N10 to N150 was measured using a CdTe diode and corrected for some physical effects that cause distortions. The corrected spectra were compared to SpekCalc analytical spectra, in terms of their shape and mean energy, as well as with the correction made by Santos (2013), a highly cited reference. It was observed that the differences between computed mean energy of corrected spectra for both approaches are inside of norm tolerance (5%), except for N150, where both shape and mean energy are slightly different, with an error of 6,5% by this work correction and 5,1% by Santos (2013). It should be mentioned that the shape of both corrected spectra converges qualitatively with those from SpekCalc, except for N120 and N150 where there is a longer low energy tail on both corrections. These results suggest that the Stripping method is suitable for the diagnostic energy range.