Efficiency of Gd2O2S: Eu Powder Phosphor as X-Ray to Light Converter under Radiographic Imaging Conditions

The aim of the present study was to examine the Gd2O2S:Eu powder scintillator under general X-ray Radiographic imaging conditions. For this purpose five scintillator screens with coating thicknesses 33.1, 46.4, 63.1, 78.3 and 139.8 mg/cm2 were prepared in our laboratory by sedimentation of Gd2O2S:Eu powder. Light emission efficiency and optical emission spectra of the screens were measured under X-ray excitation using X-ray tube voltages (50-140 kVp) employed in X-ray radiography. Spectral compatibility with various optical photon detectors (photodiodes, photocathodes, charge coupled devices, films) were determined using emission spectrum data. In addition, parameters related to X-ray detection and energy absorption efficiency were calculated. Gd2O2S:Eu showed peak emission in the wavelength range 620-630 nm. The 139.8 mg/cm2 phosphor screen appeared with the maximum light emission efficiency. Due to its reddish emission spectrum, Gd2O2S:Eu showed excellent compatibility with the sensitivity of many currently used photodetectors and could be considered for application in X-ray imaging especially in various digital detectors.