A research prototype system for quantum-counting clinical CT

Recent publications emphasize the benefits of quantum-counting applied to the field of Computed Tomography (CT). We present a research prototype scanner with a CdTe-based quantum-counting detector and 20 cm field-of-view (FOV). As of today there is no direct converter material on the market able to operate reliably in the harsh high-flux regime of clinical CT scanners. Nevertheless, we investigate the CT imaging performance that could be expected with high-flux capable material. Therefore we chose pixel sizes of 0.05 mm2, a good compromise between high-flux counting ability and energy resolution. Every pixel is equipped with two energy threshold counters, enabling contrast-optimization and dual-energy scans. We present a first quantitative analysis of contrast measurements, in which we limit ourselves to a low-flux scenario. Using an Iodine-based contrast agent, we find 17% contrast enhancement at 120 kVp, compared to energy-integrating CT. In addition, the general dual-energy capability was confirmed in first measurements. We conclude our work by demonstrating good agreement of measurement results and detailed CT-system simulations.