System performance of phosphor screen coupled CMOS imager for long-term radiation exposure

We present the performances of a scintillator coupled CMOS APS imager under cumulative X-ray exposure conditions in terms of the modulation transfer function (MTF), noise power spectrum, and detective quantum efficiency (DQE). An industrial X-ray generator with the condition of 50 kVp/500 μA was used to take cumulative exposure conditions. The experimental results show that the MTF and DQE exponentially degraded because of direct X-ray exposure of the imager through the scintillator. For the given scintillator and radiation exposure, the system performance of the scintillator coupled CMOS APS imager can be predicted.