dose distribution and dosimetry parameters calculation of med3633 palladium-103 source in water phantom using mcnp

background: palladium-103 (103pd) is a brachytherapy source for cancer treatment. the monte carlo codes are usually applied for dose distribution and effect of shieldings. monte carlo calculation of dose distribution in water phantom due to a med3633 103pd source is presented in this work. materials and methods: the dose distribution around the 103pd model med3633 located in the center of 30×30×30 cm3 water phantom cube was calculated using mcnp code by the monte carlo method. the percentage depth dose (pdd) variation along the different axis parallel and perpendicular to the source was also calculated. then, the isodose curves for 100%, 75%, 50% and 25% pdd and dosimetry parameters of tg-43 protocol were determined. results: the results show that the monte carlo method could calculate dose deposition in high gradient region, near the source, accurately. the isodose curves and dosimetric characteristics obtained for med3633 103pd source are in good agreement with published results. conclusion: the isodose curves of the med3633 103pd source have been derived form dose calculation by mcnp code. the calculated dosimetry parameters for the source agree quite well with their monte carlo calculated and experimental measurement values.