Experimental characterization of an X-ray photon counting detector

Abstract

This paper presents the experimental test results of the X-ray photon counting detectors based on our pixel readout ASIC. The chip integrates a 64 × 128 array of pixels in the size of 150 µm × 150 µm and each pixel consists of four 12-bit energy windows. Two types of CdTe detectors have been bump bonded to the ASICs and have been tested.The electronic characteristics of the readout chip were evaluated first by injecting charge through the calibration capacitors. The non-uniformity of the energy thresholds among pixels was measured and then were compensated by tuning the local DACs.The detector performance was then characterized using X-ray tubes. The energy responses of the detectors were measured using the characteristic X-ray of the target materials. The global energy thresholds were then calibrated with these specific energies of photons. Polarization effects under different photon fluxes were also studied. Preliminary imaging was conducted. The detector response under uniform irradiation was investigated. The spatial uniformity of the detectors was analyzed and the flat field correction was then conducted to improve image quality. CT detailed test results will be discussed in this paper.