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

An iterative algorithm that reconstructs the attenuation map and emission activity 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 the attenuation map from the previous iteration. Then, the attenuation map is estimated by using the current emission image. To effectively locate the attenuation map within a possible class of solutions the attenuation map is constrained by an optimal basis set, which is derived from a cross-correlation of a priori images known as a “knowledge set.” Computer simulations show that the proposed algorithm has the capability to reconstruct the emission activity distribution and the transmission map without the use of transmission measurements. The proposed method has been tested using clinically acquired data