1. Department of Electrical and Computer Engineering, University of Massachusetts Lowell, Lowell, MA, USA
2. Biomedical Imaging Center, Center for Biotechnology and Interdisciplinary Studies, Department of Biomedical Engineering, Rensselaer Polytechnic Institute, Troy, NY, USA
3. LMAM, School of Mathematical Sciences, Peking University, Beijing, China
4. CT Systems and Applications Laboratory, GE Global Research Center, Niskayuna, NY, USA