The feasibility analysis of omission of elective irradiation to level IB lymph nodes in low-risk nasopharyngeal carcinoma based on the 2013 updated consensus guideline for neck nodal levels. - Ou, Xiaomin; Miao, Yibing; Wang, Xiaoshen; Ding, Jianhui; He, Xiayun; Hu, Chaosu (Radiation Oncology, 2017)