Release criteria from hospitals of 131I thyrotoxicosis therapy patients in developing countries--case study.

The current release limit, recommended by the International Atomic Energy Agency (IAEA)(1), from hospitals of patients undergoing 131I thyrotoxicosis therapy is approximately 1100 MBq (approximately 30 mCi). Owing to the difference in socio-economic conditions, literacy rate, family system, etc., this release limit may not be applicable in most of the developing countries like Pakistan. Therefore, the prime objective of this case study was to re-evaluate the release criteria for 131I thyrotoxicosis therapy patients by taking into account their lifestyle, economic conditions and other facilities such as availability of private/public transport, etc. In this context, systematic studies were carried out and 50 patients (i.e. 35 outpatients and 15 inpatients) at the Nuclear Medicine Oncology and Radiotherapy Institute (NORI), Islamabad, were studied. Exposure rate at the surface of the body and at a distance of 1 m from the standing patient was measured. Results obtained from this study showed that the dose equivalent delivered by these patients to their family members (particularly children) and general public was higher than annual dose limits recommended by the International Commission for Radiation Protection in their report ICRP Publication 60(2). In the light of this study, it is recommended that the release activity limit of approximately 370 MBq (or dose rate level of approximately 10 microSv h-1 at 1 m from the patient) be adopted instead of approximately 1100 MBq in developing countries like Pakistan.