1. School of Computer and Information Technology, Beijing Jiaotong University, Beijing, China
2. School of Engineering Medicine, Beihang University, Beijing, China
3. CAS Key Laboratory of Molecular Imaging, Beijing Key Laboratory of Molecular Imaging, Institute of Automation, Beijing, China
4. School of Computer Science and Engineering, Southeast University, Nanjing, China
5. CAS Key Laboratory of Molecular Imaging, Beijing Key Laboratory of Molecular Imaging, Institute of Automation, Chinese Academy of Sciences, Beijing, China