Avaliação de dose periférica em radioterapia de face com o objeto simulador antropomórfico utilizando filmes radiocrômicos

Abstract

This article aims to study the peripheral doses in face radiotherapy with an anthropomorphic simulator using radiochromic films. To carry out the work was used EBT3 film Ashland, anthropomorphic simulator object Alderson Rando Phantom (ARP), ionization chambers Freiburg PTW Farmer and Exradin A12 Farmer calibrated and linear accelerators, Varian Clinac 2100 and Varian Clinac 600C / D with beam of 6 MV. Two different 10 cm x 10 cm field situations were used with collimators at zero and ninety degrees. The films were positioned on 6 anatomical regions. The higher doses were in the parotid gland and thyroid on both machines. The major difference in the dose received was the comparison with the MLC of the 2 machines which can be suggested as difference in equipment construction and blade spacing, which in the 2100 has 52 sheets of 1.0 cm and in the 600 C / D3 120 0.5 cm in the middle and 1.0 cm in the extremities. When rotated the collimator ninety degrees was observed a higher dose in parotid gland which can lead to the hypothesis that the internal arrangement of the collimator contributes to the value difference. At the end, the dose percentages at the points of interest relative to the dose at the target, considering that the films were irradiated in the 10 cm x 10 cm field buildup, being 1 cGy / UM, were high in parotid and thyroid considering the others. Approximately 1% in parotid and thyroid in AL 600 C / D3 with gantry at 0 degree, while in AL 2100 2,44% in parotid and 1,15% in thyroid. In the other structures the percentages were less than 1% in relation to the target dose. Thus, the results foster further discussions about the dose dispersion allegedly caused by collimators and the construction of ALs.