Improvements in the dosimetric models of selected benthic organisms

Abstract

The International Commission on Radiological Protection (ICRP) has modeled twelve reference animal and plant (RAP) species using simple geometric shapes in Monte–Carlo (MCNP) based simulations. The focus has now shifted to creating voxel phantoms of each RAP to advance the understanding of radiation interactions in nonhuman biota. The work contained herein presents results for the voxel phantom of the Dungeness crab, Metacarcinus magister, the Sand Dab, Limanda limanda, and the brown seaweed, Fucus vesiculosus, and details a generalized framework for creating voxel phantoms of the other RAPs. Absorbed fractions (AFs) for all identified organs were calculated at several discrete initial energies: 0.01, 0.015, 0.02, 0.03, 0.05, 0.1, 0.2, 0.5, 1.0, 1.5, 2.0, and 4.0 MeV for photons and 0.1, 0.2, 0.4, 0.5, 0.7, 1.0, 1.5, 2.0 and 4.0 MeV for electrons. AFs were then tabulated for each organ as a source and target at each energy listed above. AFs whose error exceeded 5% are marked with an underline in the data tables; AFs whose error was higher than 10% are shown in the tabulated data as a dashed line. The AF’s were highly dependent on organ mass and geometry. For photons above 0.5 MeV and electrons above 0.2-0.4 MeV a nontrivial amount of energy escapes the source organ.