Gantry specifications for a dual modality imaging system for small animals

Dual modality imaging systems are powerful tools that allow researchers to correlate anatomical information with functional imaging. We are building such an imaging system to perform x-ray computed tomography (CT) and radionuclide imaging on smaller species such as mice and rats for biomedical research. A cone-beam microCT system using a microfocus x-ray tube and a CCD based x-ray detector with be mounted on an integrated gantry with a microSPECT system with up to four solid-state gamma cameras fitted with pinhole collimators. The system will allow the animal to be imaged horizontally in a physiologically natural position, and will incorporate a slip ring gantry for helical scanning. CT with spatial resolution of 0.1 mm can be generated using a step-and-shoot acquisition with rotational steps no greater than 0.35° and with angular position accuracy of ±0.01°. Alternatively, images can be acquired with continuous gantry movement if the exposure time per angular sample is limited to <0.1°. The gantry will also translate the subject horizontally at least 40 cm to allow imaging rats and other larger species. The gantry will allow transmission of x-ray and radionuclide detector data and control/status signals across a fiber optic rotary joint at data transmission rates estimated to be 30 Mbit/s for x-ray imaging and 3 Mbit/s for radionuclide image data. The completed system will be used for studying murine models of cancer and hera.