Photon Counting Detector-based Multi-energy Cone Beam CT Platform for Preclinical Small Animal Radiation Research

We reported our developments of a photon counting detector (PCD) based multi-energy cone beam CT (ME-CBCT) for preclinical small animal radiation research. The development was based on an existing preclinical small animal irradiator that includes a gantry mounted x-ray tube for imaging and radiation experiments in a self-shielded cabinet. We installed a PCD on the gantry and developed the data acquisition, processing, and image reconstruction pipeline to reconstruct CBCT images at three energy channels. We determined the optimal energy thresholds as 26, 56, and 90 keV to achieve uniform signal-to-noise ratio among energy channels. Pixel-based detector response calibration was performed to remove ring artifacts in the reconstructed CBCT images. The average difference between measured x-ray attenuation coefficients of targeted materials from ME-CBCT images and analytically calculated values was 10%. We decomposed the ME-CBCT images into images of water and bone material via an optimization model. The PCD-based ME-CBCT is expected to facilitate critical tasks in preclinical small animal irradiation researches, such as improved accuracy of radiation dose calculations in experiment planning.