Standardization of 67Ga by live-timed anti-concidence counting with extending dead time

Primary standardization of activity using the coincidence method based on analogue instrumentation

“…Considered as an important alternative to the classical coincidence method, anti-coincidence counting offers the advantage of avoiding the use of a resolving time and, as a result, its associated corrections (accidental coincidences, Gandy effect). Moreover, it becomes particularly interesting for radionuclides having a delayed γ -emission with a reduced half-life (a few microseconds); indeed, when a live-timed anti-coincidence system is used, the standardization of the radiopharmaceutical 67 Ga is performed as for a prompt β-γ emitter by setting the extendable dead time to 100 µs [60,61]. In that case, anti-coincidence counting avoids the infinite dead time extrapolation method suggested when a classical system is used [62].…”

“…Since 1959 [2], several authors have treated the problem concerning dead-time counting losses and accidental coincidences and have derived various approximate correction formulae [5]. In 1975, a high count rate 60 Co source comparison [9] revealed systematic discrepancies due to the inadequacy of the available formulae. These discrepancies were reduced using the formulation developed by Cox and Isham [10] and afterwards extended by Smith [11][12][13] and Funck [14], who considered time jitter effects and out-ofchannel events [5].…”