Internal dosimetry of radioiodine using ICRP reference phantoms and updated biokinetic model

The purpose of this study is to estimate internal dose to human body due to administration of I-131 using new biokinetic model of iodine. In this respect, we used international commission on radiological protection (ICRP) adult reference phantoms. Monte Carlo calculations were performed using MCNPX 2.6 code. The average dose to target organ per disintegration inside source organ, namely S factor, was estimated using F6 and *F8 tallies, and then compared to those from previous studies. The results show that the difference between S factors is on average less than 8%. Furthermore, the variations caused by different 131I decay spectrums were investigated. Finally, the absorbed and the effective doses were obtained for adult female and male ICRP reference phantoms considering two biokinetic models. To conclude, using different tallies and decay spectrums, as well as, various biokinetic models could affect considerably on the amount of estimated internal dose.