Image reconstruction from truncated data in SPECT with uniform attenuation

We prove that accurate SPECT reconstruction of a region-of-interest (ROI) in the activity map is possible from truncated projections collected over 180 degrees, assuming that the attenuation map is constant in a convex region Omega that includes all activity sources. The amount of allowable truncation depends on the size and location of the ROI relative to the direction of the first and last projections and relative to the boundary of Omega. A sketch of the proof is given along with reconstructions from computer-simulated data in support of the theory. Our result may be seen as an extension to SPECT of recent results obtained in classical tomography.