Visual Monte Carlo and the Simulation of Whole Body Counter and Gamma Camera Counting Systems

The Monte Carlo program Visual Monte Carlo in vivo (VMC in-vivo) was developed and tested over thirteen years at the Instituto de Radioprotecao e Dosimetria (IRD), Rio de Janeiro, Brazil. VMC in-vivo has been extensively validated through international intercomparisons and is available for free download. The program simulates the geometry of Whole Body Counter (WBC) and Gamma-Camera Counting systems. The available phantoms are an anthropomorphic phantom of the whole body, a BOMAB phantom, and the University of Cincinnati knee phantom. VMC in-vivo was originally developed, starting in 1994, to perform photon transport through voxel structures followed by the detection of the photons. In this way, calibration factors were obtained relevant to WBC systems. The resulting program, VMC in-vivo was used in 2001 to perform the calculations for the international WBC intercomparison promoted by the IAEA. VMC was also modified to perform equivalent and effective dose calculations due to gamma emitters, and was also modified to transport protons and alpha particles through voxel structures. Intensive validation work was done involving comparisons of VMC results against physical phantoms, other Monte Carlo programs, and also in other international intercomparisons such in the calculations relevant to the 2007 CONRAD WP4-WP5 intercomparison “Monte Carlo modelling for in-vivo measurements of Americium in a knee phantom”. The good results obtained in the two intercomparisons show that VMC in-vivo can be used to calculate calibration factors for WBC systems.