High-sensitivity Single-Photon Emission Computed Tomography (SPECT): Safer, faster, and more accurate SPECT

A method and apparatus are described for high-sensitivity Single-Photon Emission Computed Tomography (SPECT). The apparatus includes a two-dimensional (2D) gamma detector array that, unlike a conventional SPECT machine, moves to different positions in a three-dimensional (3D) volume space near an emission source and records a data vector g which is a measure of gamma emission field. In particular, the 3D volume space in which emission data g is measured extends substantially along a radial direction r pointing away from the emission source, and unlike a conventional SPECT machine, each photon detector element in the 2D gamma detector array is provided with a very large collimator aperture. Data g is related to the 3D spatial density distribution f of the emission source, noise vector n, and a system matrix H of the SPECT apparatus through the linear system of equations g = Hf+n. This equation is solved for f by a method that reduces the effect of noise.