Methodology development for dosimetry of 90Sr + 90Y beta therapy applicators

The 90Sr+90Y applicators, used in beta therapy for prevention of keloids and pterigio, are imported and its dosimetric features are only illustrated by the manufacturers. The exhaustive routine of the medical physicists in the clinic do not make possible the accomplishment of procedures for the confirmation of these parameters. This work presents a methodology development for dosimetry in two 90Sr+90Y beta therapy applicators of the Amersham brand. The Monte Carlo code MCNP 4 C was used for the simulation of the percentage depth dose curves. The experimental measurements of the radiation attenuation had been done with a mini-extrapolation chamber. The results of the experimental measures had been compared with the simulated values. Both percentage deep dose curves, the theoretical and the experimental ones, had presented similar behavior, which may validate the use of the MCNP 4 C for these simulations, strengthening the usage of this method at procedures of dosimetry of these beta radiation sources. (author)