1. Department of Radiation Oncology, Xiamen Cancer Center, The First Affiliated Hospital of Xiamen University, Xiamen, People's Republic of China.
2. State Key Laboratory for Cancer Research in Southern China, Sun Yat-sen University Cancer Center, Guangzhou, People's Republic of China.
3. Department of Radiation Oncology, Sun Yat-sen University Cancer Center, Guangzhou, People's Republic of China.
4. Department of Radiotherapy, Zhongshan Affiliated Hospital of Sun Yat-sen University, Zhongshan, People's Republic of China.