Métodos de dosimetria de superfícies aplicados ao controle de qualidade e investigação de dose na pele em tratamentos de Radioterapia

Abstract

This work was developed around the topic of the measurement of supercial doses in Radiotherapy. At this point, it has become necessary to deal with the challenging region of electronic imbalance for the accurate obtaining of dosimetric information on the surfaces. It was established the accomplishment of two works that contemplated the desired surface dosimetry. The rst work sought to evaluate the supercial doses in treatments by conformal radiotherapy, investigating the dose increase in the skin as a consequence of the use of thermoplastic immobilizers of head and neck. For the study, TLD-100 thermoluminescent dosimeters, EBT-3 radiochromic lms and computational simulations based on analytical and stochastic algorithms were used. The work developed a meticulous metrological methodology, comparing the dosimetric systems, comparing dierent types of commercial immobilizers and confronting dierent computational methods of dose calculation. The results exhibited a signicant increase in surface dose caused by the use of immobilizers. In addition, the dierent dosimetric systems were concordant in the measurements of surface doses in the unmasked simulator. The relation between the area of the orice of the masks and the total area of the masks was studied in the alteration of the magnitude of supercialisation of the dose. Finally, it was possible to discuss the implementation of corrections and dosimetric considerations in the results oered by computational algorithms on the surface of volumes treated by Radiotherapy. The second work turned to quality control in Total Body Irradiation. Based on the need to perform treatments with a high degree of dose homogeneity and precision, the use of in vivo dosimetry with TLDs was an important alternative to verify the quality of the treatment, allowing the adoption of changes if necessary . The choice of insertion positions of the TLD-100 on the skin was based on the intention to comprehensively cover all the anatomical regions of the patient, including those of smaller thickness and those with lower electronic density. The methodology included proposed corrections to reduce the error caused by known inuence factors. The results corroborated the minimum criteria for the therapeutic quality of BIT, establishing thermoluminescent dosimetry as a safe option for the quality control of these treatments