Gadolinium oxysulfide scintillator (Gd2O2S) is a high-density rare-earth ceramic material for X-ray and gamma-ray detection. This article analyzes Pr- and Tb-activated gadolinium oxysulfide, thin films and pixelated arrays, covering luminescence physics, sintering technology, emission characteristics (512–550 nm), and integration with silicon photodetectors in medical, industrial and security imaging systems.