Internal exposure rate conversion coefficients and absorbed fractions of mouse for 137Cs, 134Cs and 90Sr contamination in body

Abstract

<jats:title>Abstract</jats:title> <jats:p>The aim of this study was to determine parameters for estimating the internal exposure of all organs in mouse experiments from the radioactivity concentration in organs. The estimation of internal exposure rate conversion coefficients and absorbed fractions for 137Cs, 134Cs and 90Sr by the Particle and Heavy Ion Transport code System (PHITS) with a voxel-based mouse phantom is presented. The geometry of the voxel phantom is constructed from computer tomography images of a mouse 9 cm in length weighing 23.9 g. The voxel-based mouse phantom has the following organs: brain, skull, heart, lungs, liver, stomach, spleen, kidneys, bladder, testis and tissue (tissue and other organs). Gamma- and beta-rays from 137Cs, 134Cs and 90Sr sources in each source organ are generated and scored for every target organ. The internal exposure rate conversion coefficients and absorbed fractions are calculated from deposition energies in each target organ from each source organ and are used to generate an internal exposure rate conversion coefficient matrix and an absorbed fraction matrix. The absorbed fractions of beta-rays in the source organs are roughly 0.5–0.8 for 137Cs and 134Cs, and the absorbed fractions of gamma-rays are &amp;lt;0.04 for 137Cs and &amp;lt;0.03 for 134Cs. The internal exposure rate conversion coefficient matrix is defined using the absorbed fractions. The calculated internal exposure rate coefficient matrix is tested under a uniform radioactivity concentration of 1 Bq/kg for 137Cs, 134Cs and 90Sr. The estimated internal exposure rates in the mouse whole body for 137Cs, 134Cs and 90Sr are 3.28 × 10−3, 2.55 × 10−3 and 1.20 × 10−2 μGy/d, respectively. These values are very similar to those for an ellipsoid frog (31.4 g) and an ellipsoid crab egg mass (12.6 g) reported in ICRP Publication 108.</jats:p>

137Cesium (137Cs) assessment in wild boars from northwestern Italy

“…Also, the kidney seems to show higher contamination. This issue is interesting because distribution has been studied in several animals and insects but not in wild boar [ 21 , 34 , 36 ].…”

“…Muscle is the most common sampling site, but many authors have stressed that more data are needed on the distribution of radionuclides in the whole body to define safety limits more accurately, taking into account the distribution in the different anatomical systems and that some of the radionuclides are normally consumed [ 1 , 6 ]. This is an important aspect if we consider that biodistribution and biological half-life depend on the organ [ 21 ].…”

“…In all Europe the attention on radionuclides contamination raised after two main nuclear plant accidents: Chernobyl and Fukushima nuclear plants accidents. Both nuclear plants accidents lead to a severe contamination across Europe of Cs isotope, 134 Cesium ( 134 Cs) and 137 Cesium ( 137 Cs) even if the contamination levels varied among regions [ 21 ]. With regard to Italy, considerable levels of 137 Cs contamination were detected in the northwestern alpine region, in addition to natural sources of radionuclides.…”

Internal organ dose rate conversion coefficients of Japanese macaques to 134Cs,137Cs and 131I

“…The 3D model was converted to a DICOM image, and a voxel phantom was created using DICOM2PHITS [ 7 ]. The details of voxel phantom creation have been reported previously [ 2 ]. The created voxel-based Japanese macaque phantom has a body weight of 11.35 kg and sitting height of about 58.0 cm.…”

“…To estimate the radiation dose in the organs of a Japanese macaque sampled in the study area, a Japanese macaque voxel phantom was deemed necessary to analyze the effects of low radiation exposure such as oxidative stress. However, few studies have developed numerical phantoms for macaques, and only a few rhesus macaque phantoms have been reported as primate computational phantoms for purposes ranging from radiation-effects research to veterinary medicine, evolutionary biology and biophysics [ 2 ].…”