Comparison of the performance of the photon counting hybrid pixel camera XPAD3 versus the CCD camera DALSA XR-4 for cone-beam micro-CT

Hybrid pixel detectors represent a new generation of digital X-ray camera working in a photon counting mode that can replace conventional charge integration in 2D detectors. We compare cone-beam CT using either the hybrid pixel camera XPAD3 or the CCD camera DALSA XR-4 within the newly developed micro-CT irradiation setup PIXSCAN within a range of total integrated doses from 30 to 900 mGy. Detector stability, image uniformity, spatial resolution, noise power spectrum, and detectability at low contrast were studied for both cameras. The results we obtained confirmed the absence of dark current for the hybrid pixel photon counting camera XPAD3, although the two detectors are virtually equivalent in standard conditions. The linearity of the CT value is demonstrated for both cameras, but the achieved contrast and spatial resolution are noticeably better with the hybrid pixel camera than with the CCD camera.