Organ dose conversion coefficients for 0.1-10 MeV electrons calculated for the VIP-Man tomographic model

A whole-body tomographic model, called VIP-Man, was recently developed at Rensselaer Polytechnic Institute from the high-resolution color photographic images of the National Library of Medicine's Visible Human Project. An EGS4-based Monte Carlo user code, named EGS4-VLSI, was developed to efficiently transport electrons using the large image data set for VIP-Man. VIP-Man has been used to calculate doses for neutrons and photons. This paper presents a new set of fluence-to-absorbed-dose conversion coefficients for monoenergetic electron beams between 100 keV and 10 MeV for VIP-Man. Irradiation conditions include anterior-posterior, posterior-anterior, right lateral, left lateral, rotational, and isotropic source geometries. Comparisons between organ doses from VIP-Man, which is taller and heavier than the Reference Man, and existing data from mathematical models show significant discrepancies. It appears that even slight differences between body models can cause dramatic dosimetric deviations for low penetrating electron irradiation. This suggests that a single standard body model may poorly represent a large population and may not be acceptable for electron dosimetry.