1. Key Laboratory of Optoelectronics Technology and System, Ministry of Education, Chongqing University, Chongqing, China
2. Department of Biomedical Engineering, Rensselaer Polytechnic Institute, Troy, NY, USA
3. Division of Nuclear Technology and Applications, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, China
4. Beijing Engineering Research Center of Radiographic Techniques and Equipment, Beijing, China