A dagger photon counting detector system for both 2D and 3D interventional imaging

C-arm x-ray systems equipped with flat panel detectors (FPD) lack spectral and ultra-high-resolution (UHR) capabilities desired by physicians for image guided interventions (IGIs), for example to discriminate between and/or quantify different materials such as iodine and calcium, or in the visualization of very fine structures or devices used in interventional procedures. Photon counting detectors (PCDs) can introduce these capabilities to the interventional suite: In this work, we propose a new dagger-shaped PCD design tailored for IGIs to upgrade the imaging capabilities in the C-arm interventional system while preserving the functionality of the existing FPD and reducing the system cost compared to completely replacing the FPD with a large-area PCD. The design consists of two modules integrated together: One is a long-strip shape for narrow-beam spectral and UHR CT with full axial coverage, and one is rectangle-shaped for volume- and region-of-interest 2D and 3D spectral and UHR imaging. As a proof of concept, prototypes of each module were used to perform phantom and in vivo animal experiments. Results show the potential of the proposed design in discriminating between and quantifying iodine and calcium by leveraging the spectral information provided by PCDs. UHR 2D and 3D PCD images show the improved capabilities of the dagger PCD in delineating small blood vessels with improved contrast-to-noise ratios, as well as resolving fine structures such as stents commonly used in IGIs.