DOSE CONVERSION COEFFICIENTS FROM MONOENERGETIC NEUTRONS COMPUTED WITH THE MCNP6.2 CODE IN THE VIP-MAN PHANTOM.

Computational estimates of dosimetric quantities from external exposures to neutron fields are valuable to ongoing radiation protection studies that are of interest to US defense-focused organizations. Conversion coefficients for fluence-to-absorbed dose and fluence-to-effective dose were computed using version 6.2 of the Monte Carlo N-Particle® code (MCNP6.2) in the visible photographic man (VIP-Man) numerical model for 45 monoenergetic neutron fields between 10-9 and 20 MeV under six irradiation geometries. Comparisons to the formative VIP-Man study by Bozkurt et al. revealed excellent agreement. The mean relative difference between our VIP-Man/MCNP6.2-computed and the International Commission on Radiological Protection (ICRP) 116-published absorbed dose conversion coefficients in 14 organs and remainder tissues under all geometries was 4.7%, which is within ICRP-reported variations. The effective dose coefficients computed with VIP-Man/MCNP6.2 were strongly similar to ICRP 116 values in all geometries except for posterior-anterior, where the difference was attributed to shielding of anterior organs by the relatively fatty composition of the VIP-Man phantom.