On the response of a europium doped phosphor-coated CMOS digital imaging detector

Purpose: The purpose of the present study was to assess the information content of a high resolution active pixel CMOS imaging sensor coupled to Gd2O2S:Eu phosphor screens in terms of single index image quality metrics such as the information capacity (IC) and the noise equivalent passband (Ne). Methods: The CMOS sensor was coupled to two Gd2O2S:Eu scintillator screens with coating thicknesses of 33.3 and 65.1 mg/cm 2 . IC and Ne were obtained by means of experimentally determined parameters such as the modulation transfer function (MTF), the detective quantum efficiency (DQE) and the noise equivalent quanta (NEQ). Measurements were performed using the standard IEC-RQA5 radiation beam quality (70 kVp) and a W/Rh beam quality (28 kVp). Results: It was found that the detector response function was linear for the exposure ranges under investigation. At 70 kVp, under the RQA 5 conditions IC values were found to range between 1730 and 1851 bits/mm 2 and Ne values were found between 2.28 and 2.52 mm � 1 . At 28 kVp the corresponding IC values were found to range between 2535 and 2747 bits/mm 2 , while the Ne values were found between 5.91 and 7.09 mm � 1 . Conclusion: IC and Ne of the red emitting phosphor/CMOS sensor combination were found with high values suggesting an acceptable imaging performance in terms of information content and sharpness, for X-ray digital imaging.