radial dose functions of gzp6 intracavitary brachytherapy 60co sources: treatment planning system versus monte carlo calculations

background: the monte carlo (mc) method is not only used for dose calculations around brachytherapy sources but also for benchmarking treatment planning systems (tps) calculations. materials and methods: three 60co sources of gzp6 brachytherapy unit were simulated using mcnp4c mc code. the radial dose functions were calculated by mc method and gzp6 tps and were compared. results: there was a good agreement between mc and tps calculations for all sources. discrepancies up to 10% were observed for points close to the sources, but for those farther than 7mm from source center, differences were less than 2% for all sources. conclusion: our results showed that gzp6 tps calculations can accurately be used for dose calculations in brachytherapy treatments for points farther than 7mm from the source center.