Performance of a device to minimise radiation dose to the hands during radioactive syringe calibration

The preparation of syringes for routine applications in nuclear medicine, and in particular the calibration procedure, is associated with high radiation exposure to the hands. To reduce this radiation burden, our group developed a modified calibration procedure based on a device that we refer to as the ActivoFix, which allows syringes to be drawn up inside the dose calibrator. This study investigated the performance of the new device as compared to the usual procedure of syringe calibration with regard to the absorbed radiation dose to the hands (fingertips and middle finger bases), the precision of the calibration procedure and the time required to calibrate syringes. Fourteen experienced nuclear medicine technologists drew up syringes from an initial eluate of 8.2 GBq using the conventional technique and the new calibration procedure. All technologists had to calibrate syringes with 50 MBq, 250 MBq and 650 MBq. This sequence was repeated four times using the conventional technique and then the new procedure. The equivalent dose to the hands was measured with thermoluminescent dosimeters. The exact amount of radioactivity in the syringe and the time needed for the calibration procedure were also recorded. The reduction in equivalent dose using the new device compared with the routine procedure ranged from 8.3- to 19.6-fold (mean 14.3-fold) for the fingers of the dominant hand and from 13.6- to 40.3-fold (mean 27-fold) for those of the non-dominant hand (total mean 21.3-fold). For small volumes, time could be saved with the ActivoFix, whereas for greater volumes time was lost. The device produced less variability in calibrating doses at 250 MBq and 650 MBq. Following the ALARA principle, the new device can be recommended for syringe calibration in nuclear medicine because the use of the ActivoFix-based procedure reduces finger dose by an average factor of 21, improves the precision of calibration and reduces the filling time for small volumes.