SPECT imaging reconstruction through discretization on a polar grid

The problem of reconstructing a two-dimensional tomographic medical image is considered. The emission function $f(P)$ is defined on a plane circular domain $\Omega$ and has to be reconstructed from data collected by SPECT. In this paper the natural pixel discretization approach is used, for which suitable basis functions must be chosen. We show that by choosing the basis on a polar grid a highly structured coefficient matrix can be obtained. Numerical experimentation validates the efficiency of this approach.