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Rapid sequence angiography with a 3D printed aneurysm phantom and an ultra-high frame rate imaging photon counting detector (PCD)

Temporal and spatial details of vascular flow patterns and rates in neuro and cardio vascular pathology are difficult to evaluate even with so-called “real-time” 15 or 30 fps x-ray imaging using flat panel detectors (FPDs). Higher frame rates of 1000 fps with high spatial resolution of 100 um pixels can demonstrate vascular flow details previously unseen by any other means. A new ultra-high temporal and spatial resolution detector with the above capabilities, the XCounter’s Actaeon, is a direct conversion photon counting detector (PCD) with built-in electronic charge sharing correction and dual energy threshold settings. This PCD was used to image a 3D-printed realistic aneurysm flow phantom injected with both iodine and gas bubble contrast media. The flow patterns, including details of the vortex flow and velocities of individual gas bubbles, were recorded in a sequence of 1 ms images and compared with frames from standard 30 fps angiographic imaging where flow patterns were blurred and individual gas bubble movement could not be observed. Because of the low-energy threshold capability of the PCD, instrumentation noise was virtually negligible enabling quantum limited performance such that, at standard angiography dose rates for FPDs, the per frame noise quality for the 1 ms frames of the PCD sequences was acceptable. This resulted in a combination of temporal, spatial, and contrast resolution unseen previously.