1. Department of Nuclear Science & Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing, P. R. China
2. Radiotherapy Center, Subei People’s Hospital of Jiangsu province, Yangzhou, P. R. China
3. Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education Institutions, P. R. China
4. School of Electronic Science and Engineering, Nanjing University, Nanjing, P. R. China