RESUMO
PURPOSE: The intra-arterial administration of radioactive glass microspheres is an alternative therapy option for treating primary hepatocellular carcinoma, the main cause of liver cancer death, and metastatic liver cancer, another important kind of cancer induced in the liver. The technique involves the administration of radioactive microspheres in the hepatic artery, which are trapped preferentially in the tumor. METHODS: In this work the GEANT4 toolkit was used to calculate the radial dose-rate distributions in water from 32P-loaded glass microspheres and also from 90Y-loaded glass microspheres. To validate the toolkit for this application, the authors compared the dose-rate distribution of 32P and 90Y point sources in water with data from the International Commission on Radiation Units and Measurements report 72. RESULTS: Tables of radial dose-rate distributions are provided for practical use in brachytherapy planning with these microspheres. CONCLUSIONS: The simulations with the microspheres show that the shape of the beta ray energy spectra with respect to the 32P and 90Y sources is significantly modified by the glass matrix.