MONTE CARLO DOSE CALCULATIONS FOR BREAST RADIOTHERAPY USING 60Co GAMMA RAYS

The present study aims to assess radiation dose received by the target tumor cells and non-target organs during breast radiotherapy. The human body with its details, was modeled using three dimensional Monte Carlo Nuclear Particles Code (MCNP-4B). The dose distribution from 60Co γ-rays, with average energy 1.25 MeV, in two fields in humantheoretical model was calculated at selected points using the same code. Monte Carlo computer calculations of the photon spectra and the ratios of doses at the surfaces and insome of the internal organs of the model were also performed. In order to validate the calculated data, dose distribution at the same selected points were measured during a real radiotherapy practice using ARP phantom and TLD. Moreover, depth dose distribution was established by modeling water phantom with capacity 80 cm3 and measured by ion chamber0.125. Both measured and calculated data were compared. The comparison showed that the calculated and the measured data have the same behavior in different organs. The correlation coefficient of both sets of data (R) was found to be = 0.9126. The comparison between calculated and measured depth dose gives fair agreement.