NPL secondary standard radionuclide calibrator. Syringe calibration factors for radionuclides used in nuclear medicine

The measurement of the activity of a radiopharmaceutical administration to a patient is normally achieved via the use of a radionuclide calibrator. Although these radionuclides are normally measured initially in a standard glass vial, an aliquot of the solution is then usually withdrawn into a syringe prior to the administration. Both for general quality assurance good practice and for additional guarantees for patient safety, a confirmatory measurement of the syringe is almost obligatory. Because of the different geometries and elemental compositions between plastic syringes and glass vials, the calibration factors for syringes may well be significantly different from those for the glass containers. The magnitude of these differences depends on the energies of the emitted photons. A variety of syringes typically used in hospital administrations, and covering a range of volumes and manufacturers, were obtained. The results obtained were compared to those for glass vials and show the large errors that can be produced by ignoring these differences in container format.