Comparative evaluation of single crystal scintillators under x-ray imaging conditions

The present study is a comparative investigation of the luminescence properties of (Lu,Y)₂SiO₅: Ce (LYSO: Ce), YAlO₃: Ce (YAP: Ce), Gd₂SiO₅: Ce (GSO: Ce) and (Bi₄Ge₃O₁₂) BGO single crystal scintillators under x-ray excitation. Results will be of value in designing dual modality tomographic systems (PET/CT, SPECT/CT) based on a common scintillator crystal. All scintillating crystals have dimensions of 10 × 10 × 10 cm³ are non-hygroscopic exhibiting high radiation absorption efficiency in the energy range used in medical imaging applications. The comparative investigation was performed by determining the x-ray luminescence efficiency (emitted light flux over incident x-ray energy flux) in the range of x-ray energies employed in: (i) general x-ray imaging (40–140 kV, using a W/Al x-ray spectrum) and (ii) x-ray mammography imaging (22–49 kV, using a Mo/Mo x-ray spectrum). Additionally, light emission spectra of crystals at various x-ray energies were measured, in order to determine the intrinsic conversion efficiency and the spectral compatibility to optical photon detectors incorporated in medical imaging systems. The light emission performance of LYSO:Ce scintillator studied was found very high for x-ray imaging.