Enhanced Radiation Monitoring for Radiopharmacists: Quantification of Extremity Doses and Optimal Dosimeter Placement During 131I Dispensing

Occupational radiation protection remains a fundamental concern in nuclear medicine practice, particularly when handling unsealed radiopharmaceuticals such as iodine-131 (131I). Personnel involved in dispensing are at elevated risk of significant extremity exposure, especially to the fingers, due to close contact with high-activity sources. This study was conducted to quantify extremity doses among radiopharmacists during routine 131I dispensing procedures and to determine the most suitable placement of dosimeters for accurate dose monitoring. Optically stimulated luminescent dosimeters were strategically placed at multiple anatomical sites on the fingers of three radiopharmacists to capture site-specific variations in dose distribution. Results demonstrated that the highest recorded dose per dispensing procedure was 2.386 ± 0.223 mSv, with the index and thumb fingers, particularly on the non-dominant hand, receiving the greatest exposure. This finding reflects the hand positioning typically adopted during manipulation of 131I vials and syringes. Considerable variability in dose patterns between individuals highlights the importance of standardized dosimeter positioning. Regression analysis was applied to estimate fingertip doses from base measurements, but a nonlinear relationship was identified, limiting predictive accuracy. Overall, the study underscores the limitations of current monitoring practices and support the recommendation of finger base dosimetry, standardized protocols, and optimization strategies such as automation and bilateral hand monitoring to improve radiation protection for nuclear medicine professionals.