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Abstract(s)
Desde a emergência das primeiras preocupações com a possibilidade de as radiações ionizantes induzirem detrimentos à saúde humana, métodos de caracterização e medição da radiação, têm sido desenvolvidos para estabelecer princípios e sistemas de proteção radiológica. Em particular, o Decreto-Lei 108/2018 tem por desiderato a transposição para a jurisdição portuguesa da Diretiva 2013/59/Euratom, que fixa valores de dose efetiva anual, aplicáveis aos trabalhadores expostos, bem como os valores de dose equivalente destinados a certas regiões corporais, como, nomeadamente, o cristalino [1]. No domínio da estrutura ocular, a morbilidade decorrente da radiação abrange uma ampla gama de condições, com um impacto substancial na função visual, sendo a catarata um fenómeno particularmente frequente. Face a este enquadramento, emerge a necessidade premente de avaliar a carga de radiação absorvida pela estrutura ocular no decurso da exposição ocupacional dos técnicos de medicina nuclear. Estabeleceu-se a distribuição de dose intraocular nos técnicos de medicina nuclear, mais precisamente durante a administração de tecnécio-99m, através de simulações Monte Carlo. Além disso, realizou-se a medição da dose de radiação recebida pelos técnicos de medicina nuclear durante um período de trabalho efetivo, através de dosímetros termoluminescentes, com posterior extrapolação de modo a obter um valor estimado da dose anual. Os resultados evidenciaram que, de forma geral, a atividade dos técnicos de medicina nuclear está em conformidade com os limites de dose estabelecidos, tanto para a estrutura ocular como para a tiroide. Além disso, as simulações revelaram que a utilização da proteção de chumbo envolta da seringa e a rotação da mesma exercem uma influência significativa no número diário de administrações passiveis de serem realizadas, mantendo as doses de radiação a níveis aceitáveis. Foi constatado que o chumbo desempenha de maneira eficaz a função de agente de proteção, absorvendo a radiação de modo significativo, contribuindo para o reforço da segurança inerente aos procedimentos em questão. A pesquisa denota que, não obstante os técnicos de medicina nuclear encontrarem-se adstritos aos limites de exposição consignados, assume particular preponderância uma precaução na manipulação de fontes radioativas, com o desígnio de evitar eventuais riscos para a saúde. Os resultados, de forma veemente, sublinham ainda a relevância de uma abordagem individualizada no que tange à proteção radiológica, na medida em que se pondera a diversidade de sensibilidades à radiação entre diferentes regiões anatómicas.
ABSTRACT - Since the first concerns arose about the possibility of ionizing radiation harming human health, methods of characterizing and measuring radiation have been developed to prove principles and systems of radiological protection. Decree-Law 108/2018 aims to transpose Directive 2013/59/Euratom into Portuguese law, which sets annual effective dose values applicable to exposed workers, as well as dose equivalent values for certain body regions, such as the lens [1]. In the field of ocular structure, morbidity due to radiation covers a wide range of conditions, with a substantial impact on visual function, cataracts being a particularly frequent phenomenon. Against this background, there is a pressing need to assess the radiation load absorbed by the eye structure during occupational exposure of nuclear medicine technicians. The intraocular dose distribution in nuclear medicine technicians was established, specifically during the administration of technetium-99m, using Monte Carlo simulations. In addition, the radiation dose received by nuclear medicine technicians during an actual working period was measured using thermoluminescent dosimeters and then extrapolated to obtain an estimated annual dose. The results showed that, in general, the activity of nuclear medicine technicians complies with the established dose limits, both for the eye structure and for the thyroid. In addition, the simulations revealed that the use of lead shielding around the syringe and the rotation of the syringe have a significant influence on the daily number of technetium-99m administrations that can be carried out, keeping radiation doses at acceptable levels. It was found that lead effectively performs the function of a shielding agent, absorbing radiation significantly and helping to reinforce the safety inherent in the procedures in question. The research shows that, although nuclear medicine technicians are bound by the established exposure limits, caution is particularly important when managing radioactive sources, to avoid possible health risks. The results also strongly underline the importance of an individualized approach to radiological protection, as far as the diversity of sensitivities to radiation between different anatomical regions is considered.
ABSTRACT - Since the first concerns arose about the possibility of ionizing radiation harming human health, methods of characterizing and measuring radiation have been developed to prove principles and systems of radiological protection. Decree-Law 108/2018 aims to transpose Directive 2013/59/Euratom into Portuguese law, which sets annual effective dose values applicable to exposed workers, as well as dose equivalent values for certain body regions, such as the lens [1]. In the field of ocular structure, morbidity due to radiation covers a wide range of conditions, with a substantial impact on visual function, cataracts being a particularly frequent phenomenon. Against this background, there is a pressing need to assess the radiation load absorbed by the eye structure during occupational exposure of nuclear medicine technicians. The intraocular dose distribution in nuclear medicine technicians was established, specifically during the administration of technetium-99m, using Monte Carlo simulations. In addition, the radiation dose received by nuclear medicine technicians during an actual working period was measured using thermoluminescent dosimeters and then extrapolated to obtain an estimated annual dose. The results showed that, in general, the activity of nuclear medicine technicians complies with the established dose limits, both for the eye structure and for the thyroid. In addition, the simulations revealed that the use of lead shielding around the syringe and the rotation of the syringe have a significant influence on the daily number of technetium-99m administrations that can be carried out, keeping radiation doses at acceptable levels. It was found that lead effectively performs the function of a shielding agent, absorbing radiation significantly and helping to reinforce the safety inherent in the procedures in question. The research shows that, although nuclear medicine technicians are bound by the established exposure limits, caution is particularly important when managing radioactive sources, to avoid possible health risks. The results also strongly underline the importance of an individualized approach to radiological protection, as far as the diversity of sensitivities to radiation between different anatomical regions is considered.
Description
Mestrado em Engenharia Biomédica
Keywords
Medicina nuclear Exposição ocupacional Estrutura ocular Monte Carlo Dosímetro Nuclear medicine Ocular structure Dosimeter
Citation
Brito CM. Avaliação da exposição ocupacional dos técnicos de medicina nuclear a radiações ionizantes na estrutura ocular [dissertation]. Lisboa: Escola Superior de Tecnologia da Saúde de Lisboa – Instituto Superior de Engenharia de Lisboa/Instituto Politécnico de Lisboa; 2023.
Publisher
Instituto Politécnico de Lisboa, Escola Superior de Tecnologia da Saúde de Lisboa