Effective Dose Equivalents and Effective Doses for Neutrons from 30 to 180 MeV

Abstract

Monte Carlo calculations of neutron fluence-to-dose conversion factors have been performed using the Pacific Northwest Laboratory versions of the MIRD-V male and female anthropomorphic phantoms for the AP, PA, LAT, and ROT irradiation geometries. The phantoms were irradiated with monoenergetic, parallel neutron beams over the energy range from 30 to 180 MeV. The impacts of the new radiation protection quantities recommended in the International Commission on Radiological Protection (ICRP) Publication 60 were explored. Effective dose equivalents were calculated using both the ICRP 21 and ICRP 60 quality factor-LET (Q-L) relationships. The LAHET computer code was utilised to perform the energy deposition calculations for neutrons above 20 MeV. Secondary charged particles are tracked down to 1 MeV in LAHET. Lower energy neutrons and neutron-induced photons were transported using the HMCNP code and the ENDF/B-V continuous energy cross section data library. Previously calculated ambient dose equivalent and the deep dose equivalent index were found to underestimate the effective dose for energies higher than 50 MeV. Tabulations including organ dose equivalents are reported.