<qa>  What is the primary tumor of the oral cavity, pharynx, and laryThe investigators propose a prospective, randomized phase III trial in patients undergoing definitive therapy for locally advanced Stage III-IVb carcinoma involving the head and neck. This includes primary tumors of the oral cavity, pharynx, and larynx, as well as cancer of the salivary glands and squamous cell carcinoma of the skin. Patients who have realized a clinical complete response to definitive therapy will be randomized to PETCT vs. CT surveillance, to test the hypothesis that PETCT surveillance is superior to CT surveillance due to earlier diagnosis of recurrence, more timely and effective salvage, and consequent reduction in HNC mortality. The study intervention will solely be the imaging modality assigned for surveillance. All study patients will otherwise be monitored strictly according to NCCN guidelines, including history and physical examination and endoscopy where appropriate. Assigned imaging will be conducted at identical intervals. Areas suspicious for recurrence on the basis of history and physical examination, endoscopy or imaging will be biopsied. Therapeutic interventions will be determined by the treatment team, which will include at least one member from medical oncology, radiation oncology, and otolaryngologyhead and neck surgery. Patients with recurrent locoregional disease will be offered salvage treatment as indicated by the clinical situation. 