Recent Developments in Scintillation Detectors for X-Ray CT and Positron CT Applications

The scintillation detectors considered in present and future instrumentation for XCT and PCT diagnostic imaging are Bi4Ge3O12 (BGO), CdWO4, Low Afterglow CsI(Tl) and CsF. These crystals with the exception of BGO have been known to scintillate as far back as NaI(Tl); their importance emphasized by their current use in CT application is relatively new. Recent improvements in purification, growth and performance characteristics present new and valuable data to the instrument designer. An evaluation and comparison of their properties vis à vis suitability for CT applications with particular emphasis on detector efficiency, light conversion, afterglow, timing, emission spectra, and general handling properties are examined and discussed. Future trends and possible replacement by other scintillators are commented on.