Evaluation of the imaging performance of LSO powder scintillator for use in X-ray mammography

The aim of the present study was to evaluate the imaging performance of Lu2SiO5:Ce (LSO:Ce) powder scintillator for use in X-ray detectors used in mammography. LSO:Ce scintillator is a high efficiency, fast emitting material, which in single-crystal form is used in positron emission tomography detectors. A scintillating screen, with a coating thickness of 25 mg/cm2, was prepared in our laboratory from commercially available LSO:Ce powder (Phosphor Technology Ltd.). The imaging performance of the screen was assessed by experimental determination of the modulation transfer function (MTF) and the noise transfer function (NTF). Experimental MTF values were compared to data obtained by a custom Monte Carlo simulation program. Screen irradiation was performed under exposure conditions employed in mammographic applications (27 kVp, 63 mAs). MTF was determined by the Square Wave Response Function (SWRF) method whereas NTF was estimated by Noise Power Spectrum (NPS) measurements, under uniform screen irradiation. Our results showed that LSO:Ce exhibits high MTF, which is comparable to that of the commercially used Gd2O2S:Tb powder scintillator. Considering our MTF results and the fast response of LSO:Ce scintillator screen (40 ns), this material can be considered for use in X-ray mammographic detectors.