Room: Track 1
Purpose: To demonstrate the capability of a table-top x-ray imaging system to simultaneously image euthanized mice injected with contrast agents with photon-counting computed tomography (PCCT) and x-ray fluorescence CT (XFCT).
Methods: The table-top system consisted of a diagnostic x-ray tube, translation and rotation stages, a 330µm-pitch cadmium zinc telluride (CZT) photon-counting detector with six energy bins, and two CdTe spectrometers which detected fluorescent x-rays in 0.5-keV bins. The energy bin thresholds on the CZT detector were set to match the contrast agent K-edge energies, enabling K-edge PCCT. A 3cm-diameter phantom containing vials of 1% and 5% Gd and Au solutions by weight, plus a mixed 1% Gd/Au vial, was imaged. Three mice were each injected post-mortem with 0.2mL of 5% Gd, Au, or mixed Gd/Au solutions in the upper torso. Each mouse was scanned with 0.5mm Cu-filtered 120kVp x-rays at 2mA. A pencil beam geometry was used with 33 translation and 30 rotation steps to form XFCT and K-edge PCCT images. A cone beam geometry with 180 rotation steps was used to form high-resolution K-edge PCCT images. All images were calibrated to the highest 5% concentration in the phantom images.
Results: Both Gd and Au XFCT images accurately reconstructed the mixed 1% vial (0.80% and 0.82%) better than the respective pencil (0.31% and 0.71%) or cone beam (0.30% and 0.69%) K-edge PCCT images. For the mouse imaging, good contrast resolution and quantification was evident in Gd- and Au-only K-edge PCCT images. All XFCT images could reconstruct Gd contrast, however excess noise rendered Au contrast undetectable in XFCT. Mixed Gd/Au signal was diminished in the K-edge PCCT mouse images, as predicted by the phantom images.
Conclusion: This is the first demonstration of simultaneously-acquired XFCT, K-edge PCCT, and energy-integrated CT of mice injected with Gd and Au on a table-top imaging system.