Evaluation of the luminescence efficiency of YAG:Ce powder scintillating screens for use in digital mammography detectors

In the present study scintillating screens prepared from Y3Al5O12:Ce (YAG:Ce) powder phosphor were evaluated for use in digital mammography. YAG:Ce has never been previously used in x-ray medical imaging, however since it emits yellow light (i.e peak at 550nm), it is expected to match well the spectral sensitivities of most photodetectors (photodiodes, CCDs and amorphous silicon sensors) incorporated in various digital mammography detectors. YAG:Ce was purchased in powder form and was used to prepare test screens in laboratory. Screens were evaluated by determining the absolute luminescence efficiency, the light emission spectrum, the x-ray to light intrinsic conversion efficiency and the spectral compatibility with photodetectors. Results were compared with phosphor materials commercially employed in x-ray imaging. Maximum YAG:Ce emission efficiency was observed for the 63 mg/cm² screen at 49 kV. Emission spectra peaked at 553 nm. The spectral compatibility with amorphous silicon photodiodes (0.93) and CCDs (0.95) was found to be very high, better than the corresponding compatibility of the CsI:Tl, mostly used in current digital radiography detectors. Taking into account the YAG:Ce overall performance, its short decay time as well as its spectral compatibility with amorphous silicon detectors and CCDs, this phosphor could be of interest for further investigation for use in digital mammography detectors.