Inclusion Criteria:  More than or equal to 18 years old. ECOG Performance Scale (0-2). Histological confirmation of SCC of the oral cavity, oropharynx, nasopharynx, hypopharynx or larynx.  Clinical stage II-IVB (AJCC, 8th edition). Multidisciplinary decision of radical radiation or concurrent chemoradiotherapy (CCRT).  Informed consent obtained, signed and dated before specific protocol procedures.  Exclusion Criteria:  Stage I/II glottic cancer. Patients who underwent surgery for the primary tumor location. Distant metastases. Inability to undergo PET-CT or MRI. Prior invasive malignancy (except non-melanomatous skin cancer) unless disease- free for a minimum of 5 years. Prior radiotherapy to the region of the head and neck that would result in overlap of radiation fields. Any psychological, familial, sociological or geographical condition that hamper compliance with the study and/ or follow up schedule.