21: Can Intratreatment Pet CT-Based Adaptive Radiotherapy Reduce Treatment Margins in Head and Neck Cancers?. (September 2016) - Farha, Georges; Chin, Lee; Dhillon, Amanpreet; Lim-Reinders, Stephanie; Gaitan, Jidney Cifuentes; Conrad, Tatiana; Brotherston, Drew; Caldwell, Curtis; Lee, Justin; Karam, Irene; Poon, Ian