Optimization of the ICRP 67 and NCRP 156 Transfer Rates Applied to Nonhuman Primates Intramuscularly Injected With 241Am.

Nonhuman primates intramuscularly injected with Am-241 have been investigated using the International Commission on Radiological Protection Report 67 model coupled with National Council on Radiation Protection and Measurements Report 156 model. Default parameters from these models were input into the Integrated Modules for Bioassay Analysis software to predict the intake and skeleton retention in 20 tested nonhuman primates. The predictions generated were compared to the experimental data from the Durbin nonhuman primate studies. A previous study conducted by Alomairy in 2017 indicated that the early behavior of Am-241(NO3)(3) in wound cases can be explained using the default transfer rates. However, these transfer rates were not able to predict the intake and skeleton retention at the time of sacrifice after 100 d postintake due to differences in the amount of activity translocated or deposited in liver tissue and nonliver tissues (primarily skeleton). This is likely due to the physiological differences between the nonhuman primate and human. The objective of this study was to develop new transfer rate parameters for wound and systemic models in an effort to improve biokinetic predictions. Estimates of new transfer rates appropriate for nonhuman primate data were estimated by employing a companion software program called Integrated Modules for Bioassay Analysis Uncertainty Analyzer. During validation of the suggested transfer rates, it was observed that the optimized parameters predicted the intake in 66% of the tested animals used in this investigation. The activity retained in the skeleton improved in almost all cases where the differences between predicted and measured activity is less than 20%.