A photon-counting X-ray detector using SiPM and FPGA-only MVT digitizer

Multi-voltage threshold (MVT) digitizes the scintillation pulse by taking the timing samples when it crosses the predefined thresholds. In our previous work, we have demonstrated an FPGA-only MVT digitizer based on this method and developed several modularized PET detectors. It has become a promised high integration density and low cost digitizer for readout the signal from the SiPM based scintillation detector. In this work, we describe the design and implementation of a photon-counting x-ray detector using FPGA-only MVT digitizer and YSO/SiPM detector. The count-rate of the detector is measured to be as high as 1.3 Mcps/pixel and it's variation is 11.9 kcps/pixel. We also demonstrated an X-ray security inspection system by using of such detectors. Our preliminary imaging from the system indicated a spatial resolution of 1.0 line pair/mm and a wire resolution of 0.2 mm. Moreover the normalized imaging indicates that the mean value of gray scale varying with the sampling time in one channel is 253 with a standout deviation 4. And the mean gradation between channels is 253 with a standout deviation 3.