NEW SCINTILLATORS FOR X-RAY COMPUTED-TOMOGRAPHY

The conversion of X-ray radiation to visible light can be performed by luminescent materials. This effect finds an attractive application in X-ray computed tomography (XCT). The centre of the XCT system with a solid state detector arrangement is the luminescent material coupled to a photosensitive diode. The requirements for efficient luminescent materials are: high X-ray absorption, high light output, fast decay time, and low afterglow. The dominant single crystalline scintillators which meet these specifications, at least in part, are CsI:Tl, CdWO4 and ZnWO4. Recently, polycrystalline scintillators such as rare earth-doped gadolinium oxysulphide, Gd2O2S:RE, and yttrium-gadolinium oxide, (Y,Gd)2O3:RE have been created. These scintillators exhibit high chemical stability. Homogeneous incorporation of rare earth (RE) activators as well as other chemical additives is achieved by controlled ceramic processing.