Cesium Fluoride: A New Detector for Positron Emission Tomography

The ideal scintillation detector for positron tomography would be a very high Z material, nonhygroscopic, have a fast decay time, and copious light output. NaI(Tl) has good light output, and even though it is hygroscopic has found acceptance as a good scintillator. Recently BGO has been shown to satisfy the first two requirements for tomography, and has replaced NaI(Tl) as the detector of choice in tomography. However, its low light yield and poor coincidence timing make it unsuitable for fast scanners. Cesium fluoride (CsF) has been investigated by us as a possible scintillation detector for positron tomography, and shows great promise even though it is extremely hygroscopic and exhibits low scintillation efficiency as compared to NaI(Tl). Its very fast decay time, good detection efficiency, and fast coincidence timing make it an ideal detector for tomographs designed for fast dynamic studies. Moreover, it permits the incorporation of time of flight information with conventional tomography for improved signal to noise ratio in the image.