F-18 Half-life measurement using 2-gamma coincidence method

Abstract

The accuracy of the half-life measurement of short-lived radioisotopes such as positron-emitting F-18 (tau(1/2) approximate to 100 min) is limited mainly by inaccuracies in the detector counting statistics. Gamma-ray measurement with a high-activity F-18 source requires counting-loss corrections to compensate for random summing effects and the detector's dead time. In this study, we measure the half-life of F-18 with two 511-keV gamma-rays using two high-purity germanium (HPGe) detectors. The counting-loss corrections are performed via two approaches to address the problems of random coincidence summing and dead time: a half-life measurement with a Na-22 source and a Geant4 simulation of the detector response. Variations in the full-width at half maximum (FWHM) of the 511-keV peak are found to show good correlation with the random summing effect. The half-life of F-18 is estimated as 109.73 +/- 0.14 min. (C) 2015 Elsevier B.V. All rights reserved