Determinação da Dose dos Fótons Contaminantes de Feixes de Elétrons Clínicos usando o Método de Recozimento Simulado Generalizado
DOI:
https://doi.org/10.29384/rbfm.2017.v11.n2.p2-6Keywords:
recozimento simulado generalizado, fótons contaminantes, elétrons clínicos, radioterapia, PDP, MATLAB, otimizaçãoAbstract
Os feixes de elétrons clínicos são compostos por uma mistura de elétrons puros e fótons de freamento produzidos nas estruturas internas do cabeçote do acelerador bem como no ar. O conhecimento acurado desses componentes é importante para o cálculo da dose quanto para o planejamento do tratamento. Existem ao menos duas abordagens para determinar a contribuição dos fótons na porcentagem de dose em profundidade dos elétrons clínicos: a) Método Analítico que calcula a dose dos fótons a partir da prévia determinação do espectro dos fótons de freamento incidentes; b) Método de Ajuste baseado em uma formula biexponencial semiempírica em que quatro parâmetros devem ser estabelecidos a partir de métodos de otimização. Os resultados revelam que o método de recozimento simulado generalizado consegue calcular a dose dos fótons contaminantes superestimando a dose na cauda não mais do que 0,6% da dose máxima (elétrons e fótons).
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