Pattern Recognition algorithm for charge sharing compensation in single photon counting pixel detectors

Thanks to the detector technology development based on high Z materials (GaAs, CdTe, CZT, etc.), the hybrid pixel detectors with direct photon-to-charge conversion become more and more popular, even in medical applications. Single photon counting systems aim at good position resolution, so making a pixel size smaller is a general tendency in such systems. However, for the detectors with pixel pitch of about 100 mu m charge division effect becomes visible and it affects up to 20-30% of all interactions, depending on detector thickness and bias voltage. For the smaller pixel size this effect is even more pronounced. In this article we propose a new algorithm for charge sharing compensation - the Multithreshold Pattern Recognition algorithm. The algorithm was implemented in a readout circuit of pixel architecture with four energy thresholds, designed for operation with wide energy-range X-ray radiation. The simulation results and implementation details are presented in this paper.