Wafer-scale CMOS Active Pixel Sensor X-ray Detector for Digital Breast Tomosynthesis
C Zhao, A C Konstantinidis, Y Zheng, T Anaxagoras, R D Speller and J Kanicki
Wafer-scale CMOS active pixel sensors (APSs) have been developed recently for x-ray imaging applications. The small pixel pitch and low noise are very promising properties for medical imaging applications such as digital breast tomosynthesis (DBT).We evaluated experimentally and through modeling the imaging properties of a 50 μm pixel pitch CMOS APS x-ray detector. A 9-stage cascaded system model was developed for CMOS APS x-ray detectors by taking into account the device nonlinear signal and noise properties. The imaging properties such as modulation transfer function (MTF), normalized noise power spectrum (NNPS), and detective quantum efficiency (DQE) were extracted from both measurements and the nonlinear cascaded system analysis. The results show that the CMOS APS x-ray detector achieves a high spatial resolution of 10 mm−1 and a DQE of around 0.5 at spatial frequencies <1 mm−1 at Air Kerma values greater than 5.4 μGy. We believe the small pixel pitch (50 μm) and ultra-low electronic noise (~150 e-) of CMOS APS x-ray detector is suitable for distinguishing subtle microcalcifications and reducing the mean glandular dose (MGD) for DBT.
