PET IMAGING USING GAMMA-CAMERA SYSTEMS - A REVIEW

Optimized positron emission tomographs have begun to demonstrate an ev er widening range of clinical applications for positron labelled pharm aceuticals. This potential has led to a renewed interest in the use of the more widely available Anger gamma camera detectors for imaging th e 511 keV photons from the positron decay process. Two forms of detect ion can be considered: either the detection of the 511 keV photons as single events or the detection of coincidence events from the opposed pair annihilation photons. The widespread availability of dual, oppose d-pair, large field-of-view detectors has promoted the development of coincidence detection without collimation. With detector rotation, pos itron emission tomography (PET) can be performed. An alternative and l ower cost option has been the universal development of ultra high-ener gy collimators to perform single photon emission tomography (SPET) wit h 511 keV photons. This review outlines the currently available perfor mance characteristics of these two approaches and compares them with t hose from two- and three-dimensional PET optimized systems. The limita tions on the development of these systems is discussed through the ana lysis of the principles underlying both single photon and coincidence detection. Preliminary clinical experience indicates that limitations in the performance characteristics of these systems has implications f or their potential role, although applications in cardiology and oncol ogy are being pursued.