Lu2SiO5:Ce LSO scintillator is a relatively new luminescent material which has been successfully applied in positron emission tomography systems. Since it has been recently commercially available in powder form, it could be of value to investigate its performance for use in x-ray projection imaging as both physical and scintillating properties indicate a promising material for such applications. In the present study, a custom and validated Monte Carlo simulation code was used in order to examine the performance of LSO, under diagnostic radiology mammography and general radiography conditions. The Monte Carlo code was based on a model using Mie scattering theory for the description of light attenuation. Imaging characteristics, related to image brightness, spatial resolution and noise of LSO screens were predicted using only physical parameters of the phosphor. The overall performance of LSO powder phosphor screens was investigated in terms of the: i quantum detection efficiency ii emitted K-characteristic radiation iii luminescence efficiency iv modulation transfer function v Swank factor and vi zero-frequency detective quantum efficiency DQE 0 . Results were compared to the traditional rare-earth Gd2O2S:Tb GOS phosphor material. The relative luminescence efficiency of LSO phosphor was found inferior to that of GOS. This is due to the lower intrinsic conversion efficiency of LSO 0.08 instead of 0.15 of GOS and the relatively high light extinction coefficient mext of this phosphor 0.239 m−1 instead of 0.218 m−1 for GOS . However, the property of increased light extinction combined with the rather sharp angular distribution of scattered light photons anisotropy factor g=0.624 for LSO instead of 0.494 for GOS reduce lateral light spreading and improve spatial resolution. In addition, LSO screens were found to exhibit better x-ray absorption as well as higher signal to noise transfer properties in the energy range from 18 keV up to 50.2 keV e.g. DQE 0 =0.62 at 18 keV and for 34 mg/cm2, instead of 0.58 for GOS . The results indicate that certain optical properties of LSO optical extinction coefficient, scattering anisotropy factor combined with the relatively high x-ray coefficients, make this material a promising phosphor which, under appropriate conditions, could be considered for use in x-ray projection imaging detectors.