Time-of-flight method for positron tomographic imaging and state-of-the-art of detector technology for emission tomography

A new method for positron computed tomography imaging is proposed that combines the advantages of a fast and efficient detection method providing the time-of-flight information with those of the reconstruction method by backprojection. In measuring the time distribution of the events with a far greater accuracy than the transit time of a photon in the object, a gaussian spatial distribution of each event can be determined. Basic differences between the conventional method and the proposed method are clearly indicated. A theoretical comparison is given of the conventional and the TOF technique. Inorganic scintillator detectors appropriate to fast coincidence time detection are described with respect to (1) the used positron imaging crystals (cesium-fluoride) and (2) timing characteristics. (G.J.P.)