Abstract: A distortion （ D distortion） between the actual projection data of emission CT and the numerical projection data of image is defined using Bregman function.A generalized multiplicative iterative algorithm is constructed on the basis of such D distortion.It’s found that ML EM and ISRA algorithms of ECT are special instances of this algorithm.Some typical cases of the algorithm are utilized in SPECT image reconstruction from projection and many interesting results are obtained.