The luminescence properties of Lu2SiO5: Ce (LSO: Ce) and YAlO3: Ce (YAP: Ce) crystals were studied for use in medical X-ray imaging. LSO: Ce and YAP: Ce are non-hydroscopic with 7.4 g/cm3 and 5.5 g/cm3 density, and short decay time (40 ns and 30 ns respectively) scintillators. Evaluation was performed by determining the absolute luminescence efficiency (emitted light flux over incident x-ray exposure) in energies employed in general X-ray imaging (40-140 kV) and in mammographic X-ray imaging (22-49 kV). Additionally the light emission spectrum at various X-ray energies (22-140 kV), and the spectral compatibility to optical photon detectors incorporated in medical imaging systems, were determined. Furthermore, light transmission measurements were carried out in order to estimate the light transmission efficiency and to calculate their intrinsic conversion efficiency. The light emission performance of the two scintillation materials studied was found adequately high for xray imaging.