Photon-counting, energy-resolving and super-resolution phase contrast X-ray imaging using an integrating detector

• Published in: Optics express 2020-03, Vol.28 (5), p.7080-7094
• Main Authors: O'Connell, Dylan W, Morgan, Kaye S, Ruben, Gary, Schaff, Florian, Croton, Linda C P, Buckley, Genevieve A, Paganin, David M, Uesugi, Kentaro, Kitchen, Marcus J
• Format: Article
• Language: English
• ISSN: 1094-4087; 1094-4087
• DOI: 10.1364/oe.384928

This work demonstrates the use of a scientific-CMOS (sCMOS) energy-integrating detector as a photon-counting detector, thereby eliminating dark current and read-out noise issues, that simultaneously provides both energy resolution and sub-pixel spatial resolution for X-ray imaging. These capabilities are obtained by analyzing visible light photon clouds that result when X-ray photons produce fluorescence from a scintillator in front of the visible light sensor. Using low-fluence monochromatic X-ray projections to avoid overlapping photon clouds, the centroid of individual X-ray photon interactions was identified. This enabled a tripling of the spatial resolution of the detector to 6.71 ± 0.04 µm. By calculating the total charge deposited by this interaction, an energy resolution of 61.2 ± 0.1% at 17 keV was obtained. When combined with propagation-based phase contrast imaging and phase retrieval, a signal-to-noise ratio of up to 15 ± 3 was achieved for an X-ray fluence of less than 3 photons/mm .