Luminescence efficiency of Lu2SiO5:Ce (LSO) powder scintillator for X-ray medical radiography applications

This work investigates the light emission efficiency of Lu₂SiO₅:Ce (LSO) powder scintillator under X-ray radiographic imaging conditions. Powder LSO scintillator has never been previously used in X-ray imaging. For the purposes of the present study three scintillating screens with coating thickness of 63.4, 108.4 and 172.5 mg/cm², were prepared by sedimentation of LSO powder. Absolute luminescence efficiency (AE) measurements were performed in the radiographic X-ray tube voltages (40-140 kVp) range. Parameters related to X-ray detection, i.e. energy absorption efficiency and quantum detection efficiency were calculated. A theoretical model, describing radiation and light transfer, was employed to fit experimental data and to estimate values of the intrinsic conversion efficiency and the light attenuation coefficients of the scintillating screens. The spectral compatibility of the LSO powder scintillator to various radiographic optical detectors was determined by performing light emission spectrum measurements and by taking into account the spectral sensitivity of the optical sensors used in digital radiography detectors. LSO was found to exhibit higher X-ray energy absorption than currently employed scintillators (CsI:Tl and Gd₂O₂S:Tb) in the range from 40 to 70 kVp. AE was found to increase with X-ray tube voltage up to 110 kVp. Maximum AE (8.2 times 10^-6 W middot s/mR middot m²) was observed for the screen of 172.5 mg/cm².