Comparison of Photon and Electron Absorbed Fractions in Voxel-Based and Simplified Phantoms for Small Animals

Abstract

Internal dosimetry on non-human biota is getting more important from the viewpoint of radiation protection of the environment. The International Commission on Radiological Protection (ICRP) proposed the Reference Animals and Plants using simplified phantoms, such as ellipsoids and spheres, and assessed absorbed fractions (AFs) for the whole bodies. In this study, photon and electron AFs in whole body of voxel-based frog and mouse phantoms were evaluated and compared with AFs in simplified phantoms. The evaluations were done by Monte Carlo methods for voxel-based and simplified phantoms. The monoenergetic photon or electron source was considered to be distributed uniformly in whole body. There were very small differences (less than 2%) between whole-body AFs in voxel-based and simplified mouse phantoms, however, the differences were up to 24% for the voxel-based and the Reference Frog phantoms. Whole-body AFs in voxel-based and simplified phantoms demonstrated that not only mass but also shape of whole body affected AFs significantly. The results of this study may suggest the replacement of the Reference Animal phantoms by voxel-based animal phantoms to improve the accuracy of the whole-body AFs.

Application of computational models to estimate organ radiation dose in rainbow trout from uptake of molybdenum-99 with comparison to iodine-131

“…A few studies have compared the variation between different phantom types (Padilla et al, 2008;Xie et al, 2010;Mohammadi et al, 2011Mohammadi et al, , 2012Mauxion et al, 2013;Martinez et al, 2014b) with generally consistent results for whole body, but varying results for organ doses. The variation between organ doses in stylized vs voxel/hybrid models has been attributed to variation in organ shape, location, and orientation.…”

“…virtualphantoms.org/), but plant and animal model development (beyond murine models) for dosimetric purposes is limited (Zaidi and Tsui, 2009). However, as there has been increased emphasis on environmental radiation protection in recent years, some computational models have been used for this specific purpose (Kinase et al, 2008;Mohammadi et al, 2011Mohammadi et al, , 2012Caffrey and Higley, 2013;Ruedig et al, 2014;Martinez et al, 2014a,b). It is worth mentioning that all of the above mentioned studies are animal models; beyond single ellipsoid representation, very few studies have considered computational phantoms for plant internal dosimetry.…”

Creation and application of voxelised dosimetric models, and a comparison with the current methodology as used for the International Commission on Radiological Protection’s Reference Animals and Plants

“…AF data were obtained from published literature in the case of Reference Rat (Mohammadi et al, 2011(Mohammadi et al, , 2012 and Reference Crab (Caffrey and Higley, 2013), and from the Master's theses of Oregon State University students in the case of Reference Flatfish (Caffrey, 2012) and Reference Trout (Hess, MSc thesis in progress; Ruedig et al, to be published). DCFs for simplified models were taken from Publication 108 (ICRP, 2008).…”

“…RAPs and radionuclides were selected based on the availability of dosimetric data. To this end, Reference Rat, Reference Flatfish, Reference Trout, and Reference Crab were included in this analysis (Mohammadi et al., 2011, 2012; Caffrey, 2012; Caffrey and Higley, 2013; Hess, MSc thesis in progress). Seven radionuclides were selected for analysis as they represented a wide range of radiation types and energies, and are commonly encountered: 14 C, 36 Cl, 60 Co, 90 Sr, 131 I, 137 Cs, and 210 Po.…”

Assessment of radiation exposure of murine rodents at the EURT territories

“…for humans, the calculations of dose coefficients relating the intake of radionuclides and the equivalent dose in organs are made using the human voxel models. Recently, a number of animal voxel phantoms, particularly mice voxel phantoms, were developed [23][24][25][26][27].…”