Dental Management of Hyperthyroid Patients Undergoing Radioiodine Therapy: A Radiation Safety Perspective

Background: Hyperthyroidism is an endocrine disorder characterized by the excessive production of thyroid hormones (T3 and T4) by the thyroid gland. The treatment of this disease in Nuclear Medicine clinics is performed by the outpatient oral administration of radioactive iodine (RAI or I-131). The gamma radiation emitted from the patient’s body after I-131 administration may lead to radiation exposure for individuals in close proximity. Objectives: The aim of this study was to determine the safe distance and duration for a dentist to provide services to a patient who has undergone hyperthyroidism treatment, in order to ensure radiation protection. Materials and Methods: A total of 50 randomly selected patients who presented for hyperthyroidism treatment were included in this study. Of these, 31 patients were diagnosed with Graves’ disease and 19 with toxic nodular goiter. Patients were divided into two groups according to the administered therapeutic I-131 activity. Group I: ≤444 MBq (n=26), Group II: >444 MBq (n=24). External radiation exposure (dose rate) measurements were performed using a radiation detector at distances of 5 cm, 15 cm, 30 cm, 60 cm, and 100 cm from the thyroid region of each patient. Results: The administered radioiodine activities ranged from 222 MBq to 925 MBq. The most frequently used I-131 therapeutic regimen was 370 MBq, followed by 555 MBq. Dose rate measurements in Group I, 24 hours after administration, were 3528 µSv/h, 968 µSv/h, and 295 µSv/h at 5 cm, 15 cm, and 30 cm, respectively. In Group II, the corresponding values at the same distances were 5525 µSv/h, 1763 µSv/h, and 566 µSv/h. Conclusion: According to our findings, dental examination and treatment of hyperthyroid patients who received ≤444 MBq of I-131 within the first 3 days pose a radiation safety concern. For patients treated with >444 MBq of RAI, the safe approach time for dental procedures was determined to be 5 days. In the case of female and pregnant dentists, these periods should be doubled to ensure adequate radiation protection.