Avaliação dosimétrica experimental de efeitos de inomogeneidade causados por vértebras torácicas
DOI:
https://doi.org/10.29384/rbfm.2017.v11.n1.p28-34Keywords:
Radioterapia, Efeitos de inomogeneidade, Vértebras, Filmes radiocrômicosAbstract
A presença de inomogeneidades de tecido produz alterações na distribuição da dose absorvida, cuja magnitude depende das propriedades físicas desses tecidos e da qualidade da radiação. A avaliação incorreta da distribuição de dose pode afetar o controle local do tumor ou aumentar as probabilidades de complicações dos tecidos normais. O trabalho teve como objetivo investigar a influência dos efeitos de inomogeneidade de vértebras torácicas sobre a dose absorvida pelo tecido mole circundante. Os valores preditos pelo sistema de planejamento de tratamento (TPS) foram comparados às medidas experimentais com filmes radiocrômicos EBT-2 posicionados em um objeto simulador constituído somente de água e inseridos axialmente em um phantom simplificado de coluna vertebral e água. Observou-se significativa alteração do padrão de distribuição de dose, aumento da dose absorvida na interface osso-tecido mole e doses pontuais altas adjacentes ao osso em comparação com os resultados obtidos para os filmes em meio homogêneo e TPS. As medidas experimentais na água concordaram com o TPS em 1,0% no que se refere à dose modal enquanto que a maior diferença encontrada para o meio contendo as vértebras foi de 4,6%, no entanto, ambos os valores se encontram dentro da incerteza experimental.
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