MTF evaluation of a phosphor-coated CCD for x-ray imaging

A novel digital x-ray detector has been assembled. The imaging system is based on a phosphor-coated charge-coupled device (CCD) obtained by direct deposition of a gadolinium oxysulphide scintillator onto the detector surface. The modulation transfer function has been measured along the two directions of the digital coordinates with the narrow slit technique. A resolution limit of about 20 line pairs per mm has been obtained for both directions. The high spatial resolution currently demanded in mammography can be achieved with this imaging system.