Radiation exposure in thyroid cancer patients treated with radioiodine: A dental perspective

Abstract

Introduction: This study aimed to experimentally determine radiation safety criteria for dentists who examine or treat patients receiving radioactive iodine (RAI) therapy for the follow-up of differentiated thyroid cancer in the nuclear medicine department. Methods: Twenty-three patients undergoing whole-body scintigraphy with RAI were included. Each patient received 185 MBq of RAI orally on an outpatient basis and remained in lead-shielded isolation rooms for approximately two hours to allow for systemic distribution. Dose-rate measurements were then obtained along a horizontal line at distances of 5, 15, 30, 60, and 100 cm from the neck and abdominal regions. Results: During the first 0–2 hours, mean dose rates measured from the neck at 5, 15, 30, 60, and 100 cm were 584±120 µSv/h, 312±52 µSv/h, 175±36 µSv/h, 18±6 µSv/h, and 11±4 µSv/h, respectively. Based on these data, the estimated radiation dose to a dentist during close contact (5–30 cm) was 224 µSv on the first day, 117 µSv on the second day, and 3 µSv on the third day after administration. Conclusion: The permissible chairside exposure time on the first day was estimated at approximately 3.12 hours without exceeding safety limits. However, when daily dose limits derived from annual occupational exposure are considered, the third day after RAI administration was identified as the safer period for dental procedures.