Monte Carlo simulation of an Ir-192 brachytherapy source spectra, geometry and anysotropy factors using Geant4 Code

In brachytherapy cancer treatments, methods for calculation of dose delivered to tumours and organs have been continuously improving. Monte Carlo methods are an important tool in dose calculation for brachytherapy cancer treatments, where the exposition to the source planning aims at the maximization of dose deposition in the target volume, while minimizing the deposition in healthy tissues. The use of interstitial brachytherapy sources follows the recommendations of AAPM REPORT No. 51. The present work is based on Monte Carlo simulations with the GEANT4 toolkit of the dose quantities recommended by that report. An iridium-192 Buchler HDR source was simulated and the geometry of dose deposition in media and energy spectra have been obtained. Calculations also include the dose rate constant ¿, the geometry factor G(r,¿), the anisotropy function F(r,¿) and the radial dose function g(r,¿).