1. Department of Radiation Oncology, The First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi 530021, P.R. China
2. School of Public Health, Guangxi Medical University, Nanning, Guangxi 530021, P.R. China
3. Department of Radiation Oncology, Liuzhou Worker Hospital, Liuzhou, Guangxi 545000, P.R. China
4. Department of Radiation Oncology, First People's Hospital of Yulin City, Yulin, Guangxi 537000, P.R. China
5. Department of Radiation Oncology, People's Hospital of Guangxi Zhuang Autonomous Region, Nanning, Guangxi 530021, P.R. China
6. Department of Radiation Oncology, Affiliated Hospital of Guilin Medical University, Guilin, Guangxi 541000, P.R. China
7. Department of Radiation Oncology, Wuzhou Red Cross Hospital, Wuzhou, Guangxi 543000, P.R. China