Estimation and analysis of S values for ¹³¹I using paediatric mesh type reference computational phantoms

This study examines the effect of paediatric mesh-type reference computational phantoms on organ<i>S</i>values resulting from radioiodine (¹³¹I) intake. Using Geant4, we estimated¹³¹I<i>S</i>values for 30 radiosensitive target tissues due to emission from the thyroid (Target ← Thyroid) in these phantoms. Our results show that<i>S</i>values differ between male and female phantoms of the same age and<i>S</i>values also decrease as phantom age increases. The male-to-female<i>S</i>value ratio typically varies within 10%, with larger differences observed for the esophagus, extra-thoracic regions, muscles, bladder, and sex organs. On average,<i>S</i>values for mesh phantoms are approximately 17% higher than those for voxel phantoms, with larger discrepancies for organs remodelled separately in mesh phantoms. The study provides organ<i>S</i>values for the paediatric population due to¹³¹I exposure from the thyroid, based on the reference mesh-type computational phantoms, enhancing organ dose estimation in emergency situations and during radioiodine treatment.