Single Photon Emission Computed Tomography Using Multi-Slice Fan Beam Collimators

Scintillation camera systems using parallel collimation have been used for single-photon emission computed tomography (SP/ECT). A major problem is the limited resolution of present parallel-hole collimators. We have built and evaluated collimators for a SP/ECT system, consisting of two opposing LFOV scintillation cameras and a gantry, which have parallel collimation along the cranial-caudal axis of the patient and converging collimation in a direction perpendicular to this axis. The collimator converges to a line of focus located 58 cm from the collimator face and parallel to the cranial-caudal axis of the patient. Two converging collimators combined with opposing LFOV cameras are capable of simultaneously imaging 11 contiguous, 2.6 (or 1.3) cm thick, transverse sections from data collected during a single revolution of the cameras about the patient. A fan beam convolution algorithm reconstructs the transverse slices and provides partial compensation for ¿-ray attenuation. It is concluded that the fan-beam collimator system, when compared with conventional parallel-hole collimator systems, produces simultaneous improvements in SP/ECT system sensitivity and resolution. This results in improved visualization of small centrally located organs.