Comparación de dosis absorbida en agua y dosis absorbida en medio en tratamientos de próstata y cabeza y cuello. Análisis con diferentes tamaños de rejilla y curvas de calibración CT
DOI:
https://doi.org/10.37004/sefm/2022.23.1.001Palabras clave:
Dosis absorbida en agua, Dosis absorbida en medio, Monte Carlo, TPS Monaco, interfaseResumen
Se analizan las diferencias entre las distribuciones de dosis calculadas con Dw,m y Dm,m en el planificador Monaco para tratamientos de próstata y cabeza y cuello. Se realiza una división de órganos en forma de capas de diferentes espesores para evaluar la influencia del tamaño de rejilla de cálculo (3mm y 1mm) y se estudia cómo afecta la curva de calibración CT a la dosis calculada. Los resultados muestran una variación, (Dw,m - Dm,m)/Dw,m, de dosis media de 0.1%-0.3% en recto y vejiga, en torno al 1% en canal medular y cavidad oral, 3% en cabezas femorales y 7% en mandíbula. El cubrimiento del PTV es superior en Dw,m un 0.04%, 1,22% para próstata y un 0.92%, 5,8% en cabeza y cuello (V95%, V100% respectivamente). Diferencias en cabeza y cuello en cobertura al PTV, según su grado de solapamiento con hueso, son suficientemente importantes para que la elección del medio de absorción afecte al control tumoral. Las variaciones de dosis entre regiones de diferentes densidades son superiores con el tamaño de rejilla de 1mm, mostrando una mayor sensibilidad a la interfase. La variación con la curva de calibración CT solo es apreciable (0.38%) en órganos de densidad muy diferente a la del agua.
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