1. Department of Head and Neck Cancer, Cancer Center, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, P.R. China
2. Department of Radiation Physics, Cancer Center, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, P.R. China
3. Department of Radiotherapy, Tumor Hospital of Chengdu, The Seventh People's Hospital of Chengdu, Chengdu, Sichuan 610041, P.R. China
4. State Key Laboratory of Biotherapy and Cancer Center, West China Medical School, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, P.R. China
5. Department of Oncology, Xinjiang Uygur Autonomous Region People's Hospital, Urumqi, Xinjiang 830001, P.R. China
6. Department of Neurosurgery, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, P.R. China