Occupational internal monitoring in nuclear medicine service of Sainte-Anne military hospital: previous considerations and results.

The Nuclear Medicine Department of Sainte-Anne military hospital in Toulon uses 99mTc, 123I and 18F unsealed sources to provide therapeutic and diagnostic care. For a few years, only ambient air and surface monitoring were performed to check the absence of internal contamination risk for workers. To verify this risk assessment hypothesis, confirmatory monitoring programme including in vivo and in vitro measurements was performed by the French defence radiation protection service (SPRA, Clamart). Here, due to the short half-life of targeted radionuclides, the analytical sensitivity was determined with estimations of minimal detectable activities and derived recording levels. It was shown that sensitivity was sufficient to detect an internal contamination leading to an effective dose of 0.1 mSv for few days post intake. At the same time, around 20 whole-body countings were performed. Results were below minimal detectable activity and were confirmed by 24-hours urine analysis. So, actual working conditions do not lead to measurable internal contamination for nuclear medicine staff.