Lifetime attributable cancer risk assessment in pediatric patients undergoing I-124 PET for differentiated thyroid cancer.

The increasing use of I-124 PET for differentiated thyroid cancer (DTC) has raised concerns about radiation exposure in pediatric patients because of their radiosensitivity. This study estimated organ-absorbed doses and the lifetime attributable risk (LAR) of secondary cancer following I-124 PET using Monte Carlo simulations with pediatric voxel phantoms representing 10- and 15-year-old males and females. Organ doses were calculated for oral and intravenous administration under different thyroid uptake conditions, and LAR was estimated using the Biological Effects of Ionizing Radiation (BEIR) VII model. The thyroid absorbed dose was slightly higher after intravenous administration, whereas the total-body dose depended mainly on age. Younger patients showed nearly twice the LAR of older patients. Females had a higher solid cancer risk, whereas leukemia risk was greater in males. Thyroid uptake and administration route had minimal effect on LAR. These findings support individualized I-124 PET protocols to maximize diagnostic benefit while minimizing long-term radiation risk in pediatric DTC.