The paper is aimed at comparing dosimetric assessments performed with three Monte Carlo codes: EGS4, MCNP4C2 and MCNPX2.5d, and considering a realistic voxel phantom, namely the Zubal phantom, in two configurations of exposure.
The first one deals with an external irradiation corresponding to an example of a radiological accident. A photon point source (Energy = 800 keV) is placed at a distance of 1 meter in front of the thorax. The results are obtained using the EGS4 and the MCNP4C2 codes and expressed in terms of the mean absorbed dose (in Gy per source particle) for brain, lungs, liver and spleen.
The second one deals with an internal exposure corresponding to the treatment of a medullar thyroid cancer by iodine 131. The source of iodine 131 is homogeneously distributed at different levels within the following organs: liver, kidneys, thyroid (corresponding to the tumour) and whole body. The results are obtained by EGS4 and MCNPX2.5d and compared in terms of the mean absorbed dose (expressed in mGy per kBq and per hour) for liver, kidney, whole body and thyroid. Results of these two studies are presented and differences between the codes are analysed and discussed.