TTR algorithm for the inversion of the exponential X-ray transform [SPECT application]

Presents an FBP algorithm suitable for image reconstruction from exponential X-ray projections sampled on any subset of the sphere that includes great circles. This algorithm is similar to the TTR-algorithm of Ra et al. (1982) for non-attenuated projections. It is derived by combining all reconstructions that can be obtained from the subsets of measurements corresponding to a great circle. The authors' results generalize those published by I. Hazou (1988) and Weng et al. (1996) for reconstruction from projections sampled on the unit sphere. However, they remain modest as they only apply to specific sets of measurements.