Measurement of charge division in pixelated CZT

In medical X-ray imaging using semiconductor detectors, small pixels are employed to increase image resolution and count rate capability. However, the use of small pixels increases the occurrence of imaging signals that are split between neighboring pixels or even lost in the gap regions between pixels. To assess this problem monolithic pixelated CZT blocks were scanned from pixel to gap to pixel using a filtered X-ray beam and a narrow diameter collimator. A novel technique for recording and digitizing time series data from neighboring pixels for analysis offline was employed. Singles and coincidence spectra were compiled for each location and energy. The extent of charge splitting or charge loss was determined. The technique of digital summing of coincidence signals in neighboring pixels to recover split events is demonstrated.