1. Department of Radiation Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, People's Republic of China
2. Department of Radiation Oncology, Beijing Shijitan Hospital, Capital Medical University, Beijing, People's Republic of China
3. Department of Radiotherapy, Beijing Chao-yang Hospital, Capital Medical University, Beijing, People's Republic of China
4. Department of Thoracic Surgery, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, People's Republic of China