Light Emission Efficiency of ${\rm Gd}_{2} {\rm O} _{2} {\rm S}\!\!\!:\!\!\!{\rm Eu}$ (GOS:Eu) Powder Screens Under X-Ray Mammography Conditions

The aim of this study was to examine Gd₂O₂S:Eu (also known as GOS:Eu) powder scintillator under X-ray mammography imaging conditions. For this purpose, three scintillator screens with coating thicknesses of 33.1, 46.4 and 63.1 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 (22-49 kVp) employed in mammography. Spectral compatibility with various optical photon detectors (photodiodes, photocathodes, charge coupled devices, films) and intrinsic conversion efficiency value (0.12) were determined by 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 63.1 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.