Co-planar PET/CT for small animal imaging

A small animal PET/CT system based on a common rotating gantry is proposed. The PET detection subsystem is composed of two detector modules based on MLS arrays and four flat panel type PS-PMT. The CT subsystem consists in a micro-focus X-ray tube and a semiconductor X-ray detector. Space for opposed PET detectors and the CT scanner have been allocated on the same plane in such a way that the trans-axial and axial centers are common for both systems. Shielding elements have been placed around the detectors to avoid cross modality contamination. The gantry can rotate 370 degrees to provide complete data sets for the CT image reconstruction algorithm that is based on the cone beam geometry. PET image reconstruction is implemented using FBP (2D and 3D) and OSEM. Sequential acquisition protocols minimize the scan duration, and CT information can be used to implement PET imaging corrections. The coplanar configuration of this system provides intrinsically co-registered data sets, and it is not necessary to reposition the animal to perform any modality imaging, avoiding undesired animal or additional accessories movements. An additional advantage is the compactness of the system that saves space and allows a direct visual monitoring of the animal during the scan.