A method of attenuation map and emission activity reconstruction from emission data

An iterative algorithm that reconstructs the attenuation map and emission a ctivity distribution from SPECT emission data is proposed. The algorithm is based on the quasilinearized attenuated Radon transform. At each iteration of the algorithm, emission activity distribution is reconstructed using th e attenuation map from the previous iteration. Then, the attenuation map is estimated by using the current emission image. To effectively locate the a ttenuation map within a possible class of solutions the attenuation map is constrained by an optimal basis set, which is derived from a cross-correlat ion of a priori images known as a "knowledge set." Computer simulations sho w that the proposed algorithm has the capability to reconstruct the emissio n activity distribution and the transmission map without the use of transmi ssion measurements. The proposed method has been tested using clinically ac quired data.