Development of a quasi-ideal photon counting x-ray detector with spectral coincidence counters

Project Summary The proposed project aims at developing the next generation of photon counting detectors (PCDs) with multi- energy inter-pixel coincidence counter (MEICC) and digital pulse energy correction (DPEC) for x-ray computed tomography (CT). We believe that MEICC–DPEC design will bring PCDs much closer to ideal devices and brings many clinical dreams surrounding PCD CT into reality. In a prior R21 EB029739 grant, we developed MEICC concept using Monte Carlo simulations and found that MEICC improved the dose efficiency by a factor of 3.9, which is 87% (=3.9/4.5 with respect to dose efficiency) toward the ideal spectral PCD. Simulations showed that DPEC made the PCD performance almost insensitive to the intensity of x-rays. Building upon this foundation, under this BPI project, we propose to translate our theoretical results into the real world, fabricate physical application-specific integrated circuits (ASICs) with MEICC–DPEC functionality, develop algorithms to process MEICC–DPEC data, and evaluate the performance of PCD using a tabletop x-ray CT system. Our goas are to achieve Cramér–Rao lower bound values (i.e., the minimum noise variance with unbiased estimators) that are >75% lower than the current PCD with 2 energy bins for spectral imaging tasks, which corresponds to dose efficiency improvements by a factor of >4. The specific aims are: (SA1) Optimize MEICC– DPEC design parameters and develop algorithms. (SA2) Develop MEICC–DPEC PCD. (SA3) Assess MEICC– DPEC PCD using a tabletop CT system. We will compare results against (a) the same PCDs but with 2 energy bins without MEICC–DPEC, (b) a clinical PCD CT system, and (c) two clinical dual-energy CT systems. Experimental results in SA3 will be compared against computer simulation results in SA1.