The standardisation of fluorine-18

The Australian Nuclear Science and Technology Organisation (ANSTO) maintains and disseminates the Australian standards of activity measurement. The standards include all nuclear medicine gamma emitters and pure positron emitters. Calibration factors for the ANSTO 4 π ionisation chamber for pure positron emitters have been traditionally determined from primary standardisations of cobalt-60 and sodium-22. Activity estimates of pure beta emitters have been previously determined by using 4π β-γ coincidence (efficiency tracer) counting. This method was adapted to test activity estimates of short-lived pure positron emitters made using the 4 π ionisation chamber. Detailed are methods whereby the activity of fluorine-18 can be measured. The first method is an efficiency tracing method developed in this work. The method directly tests 4π ionisation chamber fluorine- 18 activity estimates. The gamma-gamma method was carried out to confirm this. 27 refs., 3 tabs., 2 figs