Assessing Lifetime Cancer Risk for Radiotherapists using the Excess Relative Risk (ERR) and Excess Absolute Risk (EAR) Models.

This research assesses the occupational radiation exposure of workers in the Radiotherapy Department at Usmanu Danfodiyo University Teaching Hospital, Sokoto, where ionizing radiation is frequently utilized. The study evaluates the annual effective dose, individual distribution ratios, and collective effective dose for the personnel. The obtained annual effective doses range from 0.25 to 2.75 mSv, and the collective effective doses range from 8.58 to 90.09 man-mSv for Administrative and Medical Physicists, respectively. No radiotherapist received an annual effective dose exceeding 5 or 10 mSv, ensuring that the lifetime cancer risk remains below 75%. This retrospective study relies on at least five years of thermoluminescent dosimetry (TLD) records to evaluate whole-body occupational exposure among personnel interacting with ionizing radiation. The TLDs were read using a Harshaw dual-4500 TLD reader on a quarterly basis over the five-year study period. The results indicate that no radiologist received an annual effective dose surpassing the 20 mSv limit recommended by UNSCEAR.