Investigation of luminescence emission properties of (Lu,Y)2SiO5:Ce (LYSO:Ce) and (Lu,Y)AlO3:Ce (LuYAP:Ce) single crystal scintillators under x-ray exposure for use in medical imaging

LYSO: Ce and LuYAP: Ce are single crystal scintillators of high density, non-hydroscopic, high light yield and short decay time and have been successfully used in small animal PET imagers. In our study, the luminescence emission properties of (Lu-0.9,Y-0.1)(2)SiO5:Ce (LYSO:Ce) and (Lu-0.7,Y-0.3)AlO3:Ce (LuYAP:Ce) crystals were investigated for use in medical x-ray imaging. Both crystal studied had dimensions of 2x2x8mm(3), with all surface polished. Evaluation was performed by determining the absolute luminescence efficiency (emitted light flux over incident x-ray exposure) in a wide range of x-ray energies employed in mammography (22-49 kVp) and in general x-ray imaging (50-140 kVp). Measurements were performed using an experimental set-up based on a photomultiplier coupled to an integration sphere. The emission spectrum under UV and x-ray excitation was measured using an optical grating monochromator to determine the spectral compatibility to optical photon detectors incorporated in medical imaging systems. Additionally, the optical characteristics such as transmission and absorption spectra were investigated and correlated with the scintillation properties. The light emission performance of the two scintillation materials studied was found adequately high for x-ray imaging.