Evaluation of x-ray detectors for dual-modality CT-SPECT animal imaging

We are developing a bench-top animal scanner that will acquire both functional SPECT images and anatomical CT images with sub-millimeter spatial resolution for both imaging modalities. This paper presents preliminary results from the evaluation of two x-ray detectors for the CT application, and dual SPECT-CT images using one of these detectors. Two phosphor-CMOS x-ray detectors, one with 48 m pixels and 5 cm x 5 cm area and the other with 50 μm pixels and 12 cm x 12 cm area, were evaluated for linearity and dynamic range. Each detector showed linearity over ~ 3 orders of magnitude, which is sufficient for mouse CT imaging. The smaller detector was mounted to an A-SPECT system, along with a custom 50 W x-ray source with focal spot size of ~ 150 μm. Phantoms and mice were scanned sequentially, SPECT followed by CT, and the resulting reconstructed images fused into a single SPECT-CT image. These preliminary results show that the two detectors evaluated for this application can successfully achieve high contrast CT images of mice and similar sized objects.