Joint activity/attenuation reconstruction in SPECT using photopeak and scatter sinograms

This work presents a joint activity/attenuation reconstruction method in SPECT, based on the maximisation of the scatter and non-scatter data joint log-likelihood. The activity image is updated with standard expectation maximisation (EM) whereas the attenuation is updated with a quasi-Newton line-search. Results on simulation demonstrates that the utilisation of scatter considerably reduces the ill-posedness of the initial reconstruction problem with non-scatter counts only. Results on phantom data show that using scatter enables myocardial reconstruction similar to an EM reconstruction with CT attenuation correction.