Development of a Flexible Benchtop Spectral Photon Counting CT System for Tissue and Material Characterization
Abstract
Purpose
Spectral photon-counting CT (SPCCT) counts individual X-ray photons and separates them into different energy windows, producing energy-resolved images from a single scan. However, commercial SPCCT systems offer limited flexibility to vary system geometry and acquisition parameters. We describe the design and initial scanning of a flexible benchtop SPCCT system intended for quantitative image development and tissue/material characterization.
Methods
The system integrates a 120 kVp X-ray tube and a Medipix3RX photon-counting detector mounted on motorized linear and rotational stages. Adjustable source-to-object, source-to-detector distances, magnification, tube voltage and current, beam filtration, energy windows and thresholds, sample rotation speed, number of projections, and scan time. The setup is installed in a lead-shielded enclosure with a door interlock tied to the X-ray tube. A cross-line laser is used to align the focal spot, detector center, and rotation axis, and a cross-hair wire phantom supports geometric calibration and alignment. In-house software synchronizes tube exposure, detector readout, and stage motion, enabling step-and-shoot circular CT and multi-energy acquisitions.
Results
Initial multi-energy scans of a material phantom and an ex vivo chicken heart produced stable reconstructions with clear anatomical detail, confirming correct alignment and basic system performance. Ring artifacts from detector non-uniformity are present and are being mitigated with improved calibration and ring-reduction algorithms.
Conclusion
The benchtop SPCCT platform enables controlled studies of geometry, filtration, and energy-threshold configuration and will serve as a testbed for optimizing quantitative spectral imaging and downstream physics-based and AI-based methods for tissue characterization and material analysis.