Analysis of scattered radiation in an irradiated body by means of the Monte Carlo simulation

In this paper, photon spectra in an irradiated body for the 60Co γ-ray has been calculated by means of the Monte Carlo simulation, and using this spectra data, the ratios of the average mass energy-absorption coefficients ((μ-baren/ρ)med,air for each field size and for each depth were calculated. (μ-baren/ρ)med,air, which has been obtained in this paper, varied with the field size and depth, and deviated from (μ-baren/ρ)med,air, which AAPM showed as being the constant, with the maximum difference being 0.84%. Cλ', which has been calculated using (μ-baren/ρ)med,air in this paper and average mass restricted stopping power ratios (L-bar/ρ)med,air shown in previous paper, deviated from Cλ', which has been calculated using (μ-baren/ρ)med,air and (L-bar/ρ)med,air shown in the AAPM protocol, with the maximum difference being 1%. (author)