Paired-organ and other selected absorbed fraction for the Korean Reference Adult Male model

Abstract

The authors have developed a mathematical model for calculating internal radionuclide dosimetry for the Korean Reference Adult Male, and have also derived paired-organ and other selected inter-organ photon-specific absorbed fractions for this model. Each lung, kidney and adrenal gland was set as a separate source region even though each of them shares an identical physiological function with their complementary half. The thyroid gland was also set as a source region. Specific absorbed fractions (SAFs) were then derived by selecting 10 photon energies from 0.02 to 4.0 MeV inclusive. For this purpose the Monte Carlo methodology was used, and the derived SAF was compared with the resulting value of MIRD Pamphlet No. 5 and ORNL TM-8381, both of which were derived on the basis of the ICRP-23 reference man. The comparison showed that MIRD No. 5 and ORNL TM-8381 resulted in a higher absorbed fraction, but the phantom created on the basis of the Korean reference man led to a higher SAF. The weight of the organs of the phantom, and the size and location of the trunk seem to account for the differences. The energy-dependent differences in the SAFs are considered to be related to the distance between the source and target regions, the composition of the intervening tissues, and the photon energies and mean free paths. Also, as a result of deriving SAFs after setting each separate lung, kidney and adrenal gland as a source region, it was found that, although they are of the same physiological function, each individual organ serves as a source region on its own. Differences were noted in SAFs exerted on the source and target organs in accordance with the location of the organs, that is, whether they were located to the left or right of the source organs. The SAF derived in this study can be used for a more accurate internal radionuclide dosimetry for Koreans and other Orientals whose physiology, lifestyle and dietary habits are similar to those of Koreans.

Input files with ORNL—mathematical phantoms of the human body for MCNP-4B

“…The first type was a family of analytical phantoms, where all organs and the whole human body were represented with 3D analytical equations [6][7][8][9][10]. The chemical constitution of different tissues presented in the human body was also given.…”

Paired organs-Should they be treated jointly or separately in internal dosimetry?

“…Such error may be avoided only when SAFs are estimated for counterpart organs separately. Kim et al 31 previously reported such differences in the SAF values of counterpart organs in Korean human mathematical phantom.…”

DynamicMC: An Open-source GUI Program Coupled with MCNP for Modeling Relative Dynamic Movement of Radioactive Source and ORNL Phantom in a 3-dimensional Radiation Field

“…Generally, three main types of widely used phantoms would be (1) analytical, (2) voxel, and (3) mesh-type phantoms. The human organs in analytical phantoms are defined using 3-dimensional (3D) analytical equations (Zankl et al 1992; Yamaguchi 1994; Chou et al 2003; Kim et al 2006). On the other hand, human organs in voxel phantoms are defined using a large number of small elements (i.e., volume-pixels) (Xu et al 2000; Caon 2004).…”