A new approach to SPECT attenuation correction without transmission measurements

We propose a new approach to correct for nonuniform photon attenuation in SPECT imaging without transmission measurements. The new method can be considered a variant of F. Natterer's (1993) method based on the consistency condition. The method is based on estimating parameters of the attenuation map model such that the consistency condition is satisfied. However, to improve the accuracy and stability of Natterer's method, we introduce two new concepts in this problem. The first new concept is a new consistency condition based on the ordered subsets EM iterative attenuation correction, which is more informative that Natterer's one. The second new concept is a topologically constrained labeling method to estimate a segmented attenuation map. This labeling method allows to deal with complicated attenuation maps consisting of more than one region or having concave boundaries. The performance of the proposed method is tested with simulated data.