Estudo da interferência da caixa de localização na qualidade da imagem tomográfica e no cálculo da dose de radiação em tratamentos de radiocirurgia

Abstract

Radiosurgery treatments require high precision because they involve lesions of small dimensions, which are treated with elevated radiation doses in a few fractionated sessions. Thus, the localization accuracy of the region of interest is very important for successful radiation therapy. In this study, the interference of the target localizer box in such procedures was investigated using tomographic images of the skull of an anthropomorphic phantom in order to simulate a radiosurgery treatment using two exposure techniques according to a protocol of the Albert Einstein Hospital. The radiosurgery treatment process was performed, including the calculation of the average radiation dose with and without tissue inhomogeneity considerations for all exposures, using the AAA and PBC dose calculation algorithms. An analysis of the variance of pixel values in the CT number histogram was also conducted in order to analyze the interference of the target localization box on the quality of the acquired tomographic images. The experiments indicate that the AAA algorithm is less susceptible to differences in the calculation of the average doses. Regarding noise, the experiments performed with the target localization box demonstrated greater loss in tomographic image quality.