Review on Recent Developments in Collimators of Single Photon Emission Computed Tomography Imaging

In single photon emission computed tomography, collimator selection, optimization, and also geometric calibration have a major impact on the acquired image quality and so on an accurate detectability and diagnosis. The collimator optimization phenomena consider some parameters such as field of view, resolution, sensitivity, resolution at depth, septal thickness and penetration for a specific application task. While the parallel hole collimator is usually used in SPECT and planar imaging but due to the limited solid angle covered by the collimator, the system sensitivity and resolution were highly reduced. Meanwhile other types of collimators such as pin-hole, multi-pin-hole, slant and slit-slat collimators were introduced with a trade-off between sensitivity and resolution. The slant collimator with a much larger solid angle potentially increase the low detection sensitivity from a thin crystal than a parallel hole. This article reviews improvements on collimators also by considering the geometry and geometric calibration methods for improving the image quality in single photon emission computed tomography.