Slice focusing collimation for single photon emission computed tomography

The authors present "slice-focusing" collimation concept for brain SPECT. Two applications of this type of collimation are exposed. In each application the performances of the slice-focusing collimation are compared with the performances of a parallel hole collimator. The first application concerns a single slice prototype tomograph (Tomoline) using two linear detectors. The spatial resolution is improved, and the number of counts by slice is multiplied by 5 for each detector. The second application is a prototype of slice-focusing collimator for scintillation camera. This collimator provides slices 2.5 cm apart. The ratio geometric efficiency / collimator spatial resolution is multiplied by 3.0. Although the applications are principally limited to brain tomography, the focusing-slice collimation allows higher efficiency than any other collimation type using orthogonal reconstruction algorithms.