The countrate performance of the volume imaging PENN-PET scanner.

The UGM PENN-PET camera uses large position sensitive detectors and operates without septa. This design results in high sensitivity and 3-D imaging capability, but poses problems in high countrate situations. The maximum true countrates and random countrates have been measured, as a function of object size in the field-of-view. The countrate performance is understood in terms of the limiting process rates and event rejection in the camera. In addition, the camera is calibrated to generate absolute activity concentrations to within 5% by correcting for system deadtime with up to 3 mCi in the field of view in brain studies (50% deadtime at 3 muCi/mL). This allows the performance of a variety of brain and body studies, and accurate quantitation of the data over a wide range of imaging countrates, from (18)F-FDG brain studies to (15)O-water dynamic brain studies.