Determination of activity meter settings for the PET nuclides ⁴⁴Sc and ⁸⁹Zr

Highlights: • Primary standardisation of ⁴⁴Sc and ⁸⁹Zr performed. • Reported dial settings for radionuclide calibrators in clinically relevant geometries. • New dial settings identified for calibrators and clinically relevant geometries. • Results provide data that did not previously exist in the literature. - Abstract: Radionuclide activity meters depend on "calibration setting numbers" that are specific for a certain combination of radionuclide, volume and geometry. This work describes their determination for two PET emerging nuclides (⁴⁴Sc and ⁸⁹Zr), three commercial activity meters (CAPINTEC CRC15 BETA, ATOMLAB BIODEX 500 and VEENSTRA VDC 405) and two geometries: 1 mL plastic syringes and 5 mL glass vials. For ⁴⁴Sc, only values for the dial setting for 5 mL ampoules were reported previously and its use for the assayed geometries would lead to significant differences. For ⁸⁹Zr more data were available in the literature, and results are provided for new geometries. All results rely on the absolute standardisation in activity of solutions of both radionuclides.