Luminescent materials are used as X-ray detectors of medical imaging systems. Out of a large variety of materials, Terbium (Tb)-activated phosphors and needle-like columnar structured CsI:Tl phosphors are currently the most widely used ones. Parameters commonly used to assess the imaging performance of luminescent materials are: the Quantum Detection Efficiency, the Luminescence Efficiency (LE), the Optical Spectral Distribution (OSD), the Modulation Transfer Function (MTF), the Noise Power Spectrum (NPS), the Detective Quantum Efficiency (DQE) and the Information Capacity (IC). The scope of the MISCIRLU project is an in depth theoretical and experimental analysis of the performance of scintillator materials as Xray detectors. The theoretical analysis is performed through Mie scattering theory, Monte Carlo simulation and analytical modeling. The experimental analysis is performed through LE, OSD, MTF and NPS measurements. The initial results of the MISCIRLU project are focused in the theoretical analysis of the luminescent materials like the effect of the grain size, detector thickness, activator importance and scintillator crystal intrinsic conversion efficiency non-proportionality. In addition MTF and NPS have been evaluated via free software tools.