Determination of organ doses in thyroid treatments with radioactive iodine by Monte Carlo simulation

Abstract

I-131 is a radioisotope widely used in nuclear medicine for the treatment of pathologies such as thyroid cancer or hyperthyroidism. When I-131 is ingested, it rapidly accumulates in the thyroid gland, emitting radiation that affects the targeted thyroid tissue while also impacting other organs. To ensure patients receive the appropriate dose for desired therapeutic outcomes while minimizing the risk of adverse effects, accurate estimations of absorbed doses after the treatment is crucial. This study focuses on evaluating organ doses following I-131 pill administration. It leverages the recent High-Resolution Anthropomorphic Computational Phantom distributed by the International Commission on Radiological Protection (ICRP), known as the Mesh Type Reference Computational Phantom. Additionally, a biokinetic analysis of iodine is conducted using a Matlab-developed tool based on the ICRP compartment model for oral iodine administration. Furthermore, Monte Carlo simulation techniques employing the MCNP6.2 code have been used to examine the radiation transport within the phantom at various time points. Consequently, the study provides dose data for each affected organ throughout the treatment, demonstrating the suitability of this simulation methodology for conducting dosimetric investigations in thyroid treatment.