Ceramic scintillators based on the composition Gd₂O₂S: Pr: Ce have high efficiency in converting X- rays into light rays,  a decay time (t_1/10 = 5.5 us) short enough to permit repeated imaging with an interval of 1 ms, low phosphorescence, and high radiation stability. Because of the combination of these properties, they have become widely used in medical computerized tomography. Gadolinium oxysulfide (Gd₂O₂S) is also to produce phosphors and scintillation ceramics for color television picture tubes, medical imaging equipment, and up conversion luminescence, due to its wide-gap (4.6– 4.8eV), high chemical stability and high density. The present GOS scintillation ceramics are very promising as scintillator materials for X-ray CT detector applications.