Application of Numerical Phantoms and MCNP Calculation for In Vivo Calibration

The paper reports on development of numeric phantoms for Monte Carlo calculations for in vivo measurements of radionuclides deposited in tissues. The individual properties of each person require rather precise geometric representations. It is particularly important for low energy gamma ray emitting sources as thorium, uranium, plutonium and other actinides. The new utility which allows automatic creation of MCNP initial file from individual scanning information, was developed. It includes segmentation of voxel matrix, obtained with computer tomography, for distinguishing tissues by level of brightness, association colors with certain tissues, source and detector specification and, finally, voxel coupling to reduce the consumed memory and increase speed of calculations.