Post-radiation primary hypothyroidism in patients with head and neck cancer: External validation of thyroid gland dose–volume constraints with long-term endocrine outcomes

James Chung Hang Chow, Jeffrey C.F. Lui, Ka Man Cheung, Anthony H.P. Tam, Martin Ho Ching LAM, Tony Y.S. Yuen, Francis K.H. Lee, Alex Leung, Kwok‐Hung Au, Wai Tong Ng, Anne W.M. Lee, Chung-Kong Kwan, Harry Yiu