External radiation exposure rate after 18F-FDG PET/CT examination

Abstract

18F fluorodeoxyglucose (FDG) is widely used for PET CT examinations; however, positron-emitting florin generates relatively high gamma radiation (511 keV) raising occupational as well as public safety concerns. This study aimed to measure the rate of radiation emitted from patients that underwent 18FDG PET/CT examination for oncological conditions, approximately 2 hours after the procedure, before and after urination. A total of 100 patients who underwent 18F-FDG PET/CT examination were included in this study. Following imaging, external radiation exposure rate was measured using proportional counter probe at 1-m distance, approximately 2 hours after the completion of imaging procedure, before and after urination. Factors effecting resulting exposure from patients were examined. The mean post-urination activity ranged between 0.2 and 6.3 μSv/h (median, 1.8 μSv/h). Presence of metastasis, tumor type and gender did not have any effect on mean post-urination activity (P>0.05 for all comparisons). Older age, greater BMI and higher administered dose were associated with higher post-urination activity (P < 0.05 for all comparisons). Findings of this study showed that 2 hours after radionuclide injection, activity rate from patients is far below the recommended limits for general population and further decreases after urination. Discharging patients at 2 hours after urination would not seem to pose radiation health risk for relatives, public or other hospital staff.