4/spl pi/ Compton imaging using a 3-D position-sensitive CdZnTe detector via weighted list-mode maximum likelihood

In this paper, we describe a 4/spl pi/ Compton imager composed of a single 15 mm /spl times/ 15 mm /spl times/ 10 mm CdZnTe detector. Full 4/spl pi/ images are reconstructed via list-mode maximum likelihood (ML). A new weighting method for ML reconstruction is proposed in which the contributions of small-uncertainty sequences are enhanced relative to sequences with large uncertainties. The new reconstruction method is compared with traditional ML techniques for measured imaging data. The 4/spl pi/ Compton imager has a measured intrinsic imaging efficiency of nearly 2% and an imaging resolution using the weighted ML reconstruction method of 17/spl deg/ at 662 keV after 10 iterations.