1. College of Precision Instrument and Optoelectronics Engineering, Tianjin University, Tianjin, China
2. Department of Statistics and Actuarial Science, The University of Hong Kong, Hong Kong, SAR, China
3. Department of Radiation Oncology, Tianjin Medical University Cancer Institute and Hospital, Key Laboratory of Cancer Prevention and Therapy, National Clinical Research Center for Cancer, Tianjin, China