Instantaneous exposure to nuclear medicine staff involved in PET-CT imaging in developing countries: experience from a tertiary care centre in India

To assess the radiation exposure to nuclear medicine staff at a positron emission tomography-computed tomography (PET-CT) centre with high patient throughput. This prospective study included 70 adult patients who underwent 18F-fluorodeoxyglucose (FDG) PET-CT for their clinical indications. The patients' actual injected FDG activity was calculated by subtracting the syringe activity (post-injection) from the loaded syringe activity (pre-injection). The instantaneous exposure to nuclear medicine staff involved in PET-CT imaging was measured. The instantaneous dose rate of the physicians was recorded during FDG injection and that of the technologist was recorded during the patient's positioning, respectively, at 1.0-m distance from the anterior chest using a calibrated portable gamma-ray survey meter. The average FDG activity injected in adult patients was 308.5 MBq (range 173.1-438.8 MBq). The instantaneous exposure to the nuclear medicine (NM) physician during the injection time was 31 mu Sv/h (14-60 mu Sv/h). The instantaneous exposure to the NM technologist during positioning was 18 (10-34) mu Sv/h. With an average of 10 patients per day, the quarterly dose to physicians was 628 mu Sv and to technologists 182 mu Sv for 300 patients. The extrapolated annual dose was 2.5 mSv for physicians and 0.7 mSv for technologists, respectively. Instantaneous exposure of nuclear medicine staff involved in PET-CT imaging at a busy tertiary care centre is within permissible limits of the International Commission on Radiological Protection (ICRP-103) (total < 100 mSv over 5 years and not > 50 mSv in a single year) and atomic energy regulatory board (total < 100 mSv over 5 years and not > 30 mSv in a single year).