Radiation Effects on the Performance of CMOS Photodiode Array Detectors and the Role of Gain-Offset Corrections

Abstract

We report the observation of performance degradation in a detector consisting of a phosphor screen and a CMOS (complementary metal-oxide-semiconductor) photodiode array under the continuous irradiation of 45-kVp x-rays. The performance was assessed in terms of dark pixel signal, dynamic range, modulation-transfer function (MTF), noise-power spectrum (NPS), and detective quantum efficiency (DQE). From the measurement results, it has been observed that the increase of dark pixel signal and the related noise gradually reduces the dynamic range as the cumulative input exposure to the detector increases. Severe degradation in NPS was observed, which gives rise to reduction in DQE as the cumulative input exposure increases. With carefully updated offset and gain correction, however, we can overcome the detrimental effects of increased dark current on NPS and DQE.

Aging of imaging properties of a CMOS flat-panel detector for dental cone-beam computed tomography

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Microtomography with sandwich detectors for small-animal bone imaging

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“…Because the systems were clinically running, we were not allowed to modify any image acquisition options. Instead of applying a typical preprocessing algorithm, such as gain-offset [21,22] and abnormal pixel corrections [23], we used the images preprocessed by the manufacturers.…”