Estimation of radiation dose to commuters using patient transport and the nursing staff from thyrotoxicosis patients treated with radioactive iodine-131 at Universitas Academic Hospital

Introduction: Thyrotoxicosis patients are treated with radioactive I-131 to control the disease. The challenge comes after the I-131 treatment. The patient needs to be accommodated in a single room and separate rooms as per SAHPRA regulations, public dose below 1 mSv/year. The patients treated at Universitas Academic Hospital (UAH) come from the Free State, Eastern Cape, Northern Cape and Lesotho. As a result of prevailing economic disparity after discharge, some patients may thus be obliged to travel long distances (4–7 h) in crowded public transportation (e.g. FS Health Patient Transport Services). The ongoing concern of the dose to nursing staff caring for these patients was also addressed. Aim: The study aimed to determine the 24 h radiation exposure from thyrotoxicosis patients' post-treatment with I-131. Methods and materials: Two electronic alarm dosimeters were used to measure radiation exposure in the room of admitted I-131 patient, and a total of 85 patients were monitored (October 2021 – December 2022). The dosimeter was at the wall (head side of the patient bed), 1.5 m above the floor, and 0.2 m from the patient's head. The second set of measurements was performed at the wall (feet side of the patient bed), 1.5 m above the floor, and 2 m from the patient's abdomen. The average time to monitor the room's radiation levels was approximately 18 h – the mean prescribed I-131 activity was 15.7 ± 2.9 (ranging from 12 mCi to 20 mCi). Results and discussion: The results show that radiation dose in the room varied from 106 μSv to 6220.0 μSv (Median: 385.0 μSv, Mean: 545.0 μSv ± 793.0 μSv) for approximately 18.6 ± 6.9 h post I-131 administration. The results indicate that the I-131 patients might give significantly higher radiation doses to other passengers using patient transport because of the reduced distance between them. The results for the second part show that radiation dose in the room varied from 32.0 μSv to 149.0 μSv (Median: 57.0 μSv, Mean; 66.8 μSv ± 35.5 μSv) for approximately 18.6 ± 2 h after I-131 administration. Conclusions: The SAHPRA regulation of isolating patients after the I-131 therapy capsule ensures that the family and public are safe from radiation exposure. The dose received by the nursing staff is low. However, the dose to passengers in patient transport can be higher if patients are treated as outpatients without considering socioeconomic factors. (authors)