Advancing pediatric organ dose assessment in radioiodine therapy with ICRP pediatric mesh-type reference computational phantoms

Abstract

The present study provides updated S values (rT ← thyroid) for 30 radiosensitive organs/tissues for pediatric patients undergoing radioiodine therapy with iodine-131, utilizing the pediatric mesh-type reference computational phantoms (MRCPs) very recently released by the International Commission on Radiological Protection (ICRP) in ICRP Publication 156. These MRCPs represent substantial anatomical and geometric advancements over previous pediatric voxel-type reference computational phantoms (VRCPs) of ICRP Publication 143, with refined thyroid positioning and sizing, along with enhancements in various organs/tissues (e.g., skeletal system and lung airway). These improvements resulted in dose differences of up to a factor of six, especially in organs/ tissues adjacent to the thyroid, compared to the VRCPs. Furthermore, age-based analyses revealed that younger (and therefore smaller-bodied) phantoms generated higher dose estimates. Gender-based analyses also showed differences at age 15, primarily due to the smaller body size of the female phantom. These findings underscore the MRCPs’ potential to improve accuracy in organ dose calculations for pediatric patients, facilitating safer, more precise applications in radioiodine therapy and advancing methodologies in health risk assessment