Dead time correction and counting statistics for positron tomography

A correction for loss of events due to dead time in dynamic positron emission tomography has been studied. The model employs a paralyzing dead time to describe the behavior of a tomograph over the range of event rates normally encountered in patient studies (up to 200,000 events/sec/detector layer). The Donner 280-Crystal Positron Tomograph is characterized by a dead time of 1.8 μsec/event for observed count rates of less than 200,000 events/sec. The dead time correction factor is 1.8 at 180,000 events/sec. The correction is applied to projection data and to region-of-interest analysis of dynamic PET studies and formulae for the covariances between corrected projection data and between counts in regions of interest in different images from the same dynamic study are established