A comparative investigation of Lu2SiO5:Ce and Gd2O2S:Eu phosphor scintillators for use in a medical imaging detectors

The dominant powder scintillator in most medical imaging modalities for decades is Gd₂O₂S:Tb due to the very good intrinsic properties and overall efficiency. Except Gd₂O₂S:Tb there are alternative powder phosphor scintillators like Lu₂SiO₅:Ce and Gd₂O₂S:Eu that has been suggested for use in various medical imaging modalities. Gd₂O₂S:Eu emits red light and can be combined mainly with digital detectors like CCDs and wavelength selective detectors. Lu₂SiO₅:Ce emits blue light and can be combined with blue sensitivity films, photocathodes and some photodiodes. For the purpose of this study two Lu₂SiO₅:Ce and Gd₂O₂S:Eu powder phosphor scintillators with screen coating thicknesses of 25 and 33 mg/cm² respectively, were prepared by the method of sedimentation in our laboratory. The output efficiency of the phosphor screens were evaluated with respect to incident exposure rate and the spatial frequency dependent Modulation Transfer Function (MTF). Furthermore the spectral compatibility of those materials with various detectors was evaluated. Results were compared to published data for the commercially employed dasiaKodak Min-R film-screen systempsila, based on a 31.7 mg/cm² thick Gd₂O₂S:Tb phosphor. For Gd₂O₂S:Eu, MTF data were found comparable to those of Gd₂O₂S:Tb, while the MTF of Lu₂SiO₅:Ce was even higher. The different spectral compatibility of these phosphors could be interesting for application based on red and blue sensitive optical sensors respectively.