Postdischarge radiation exposure from I-131 treated thyroid cancer patients: Implications for dental practice

Abstract

Objectives. This study evaluated, for the first time, the radiation exposure of dentists examining thyroid cancer patients following radioactive iodine (RAI) therapy. Study Design. External dose-rate measurements were performed at distances of 5 100 cm in 93 differentiated thyroid carcinoma(DTC) patients between Days 1 and 7 after discharge. Patients were classified according to administered RAI activity as Group I (1110 2775MBq,n=31)and Group II (3700 7400MBq,n=62). Measurements were obtained in the anterior oblique position with patients seated upright to simulate dental examination conditions. Results. In Group I, the cumulative radiation dose potentially received by a dentist was 461.75 mSv on Day 1 after discharge, decreasing to 112 mSv and 92 mSv on Days 2 and 3, respectively. In Group II, cumulative doses on Days 1 4 after discharge were 1148 mSv, 447 mSv, 73 mSv, and 37 mSv, respectively. Conclusions. The findings indicate that patients receiving <3700 MBq RAI may safely undergo dental examination approximately 24 26 hours after discharge with appropriate radiation protection precautions, whereas dental treatment in patients receiving 3700 MBq RAI should preferably be postponed for at least 48 hours to maintain occupational exposure below the 1 mSv public dose limit.