Intersticial implants of radioactive seeds are used as an efficient way of treating brain tumors. Bioglasses is an interesting alternative to the metallic implanted materials, because they can be absorved by the organism, reducing the possibilities of side effects. The present paper investigates the dosimetry by the implants performed on rabbit’s brain on the NRI/UFMG research group. The spatial distribution of the specific ionizing energy deposited per unit of mass generated by Sm-153 seeds were evaluated. A computational model of the brain’s region was built using the software SISCODES produced by the research group. The sections of the computer tomography of a rabbit, which was included on the experiment, were digitalized. Those were converted in a three dimensional voxel model, including the tissues, its chemical composition and density. A simulation of the particles transport is performed by the estocastic code MCNP5. The implants consist of 15 ceramic Ca-Si-Sm seeds enriched with Sm-153, with 1.6mm of length and 0.3mm diameter, implanted on the rabbit’s brain. It was predicted on the model three ribbons of 5 seeds each, spaced by 1.2mm, since the ribbons were in a triangular topology whose vertices were spaced by 8mm. The activities were 120MBq/seed. The results show isodose regions superposed over the rabbits’ model, reproducing the spatial energy deposition on the brain region. The absorbed dose predicted was 3.2Gy per 15 seed; however it was not enough to tumor control. The authors suggest to increase the number of seeds and activity, reduction of the space to 5-6mm among ribbons, improving dose with the beta emitting.
Bioglass; brachytherapy; dosimetry
