Examination of the Role of Detection Systems in Quantitation and Image Quality in PET

Future improvement in PET will likely be the result of the development of devices to circumvent limitations on resolution imposed by one crystal/photomultiplier (PMT) detector systems. Three types of systems are in some stage of development: (1) multiple crystals coupled to multiple PMTs in such a manner that simple digital logic codes identify crystals of interaction, (2) single or multiple crystals coupled to multiple PMTs in such a manner that analog logic systems identify crystals of interaction, and (3) small solid-state photosensors which either identify crystals of interaction with timing by the PMT or completely replace the PMT. The value of the various types of detectors must be considered in terms of the type of measurement that is to be performed. Factors that must be considered are the distribution of the radioisotope in the field-of-view, the amount of activity that may be injected because of dose considerations and the size of the structures to be imaged.