Positron emission tomography: a review of basic principles, scanner design and performance, and current systems.

S N INCE THE INCEPTION of positron emission tomography (PET) several decades ago, PET canner design and performance have improved ramatically. The number of detector elements has ncreased from 20 to 20,000 and the axial field f view from 2 to 20 cm, the spatial resolution as improved from 25 to 5 mm, and the ensitivity has increased 1000-fold.1,2 At the ame time, the clinical applications of PET have rown dramatically as well.3-5 The current article eviews the technical basis of the remarkable dvance of this modality—the underlying princiles of PET and the basic design and performance haracteristics of PET scanners—emphasizing edicated “full-ring” devices and including multiodality (ie, PET-CT) and special-purpose (ie, mall-animal) devices.