Acquisition and calibration principles for ASPECT-A SPECT camera using digital position analysis

The design of the data acquisition and calibration procedures used in the nuclear medicine SPECT camera coined ASPECT (annular single-photon-emission computed tomography) is presented. ASPECT´s unique detector is a stationary annular single-crystal NaI(Tl) scintillator used with a lightweight rotating collimator, which will provide 3-D imaging of the brain with up to sixfold improvement in sensitivity over conventional single-headed rotating gamma cameras. ASPECT is unique in other important respects. Signals from each photomultiplier are separately digitized on an event-by-event basis, with all position-analysis algorithms performed digitally. This results in significant differences from a conventional Anger camera, where the first determination of the position of a scintillation event is calculated using analog circuitry. Automated procedures enable quality control and total system calibration to be easily undertaken by the user.<>