1. Department of Oncology, The Sixth People's Hospital, Shenzhen, Guangdong 518052, P.R. China
2. Guangdong Provincial Key Laboratory of Food, Nutrition and Health, School of Public Health, Sun Yat‑sen University, Guangzhou, Guangdong 510080, P.R. China
3. Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
4. Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA