Inclusion Criteria:  T3-T4 disease with no evidence of distant metastasis. Histological diagnosis of WHO Type II or III NPC No evidence of distant metastases in staging work up (including lung, liver and bone imaging). Planned for upfront radiotherapy and/or chemotherapy. Cross sectional imaging of the primary and neck disease (MRI preferred) Performance status of ECOG grade 0 or 1 No prior tumour therapy At least 21 years of age, of either sex. Negative serum pregnancy test within 14 days prior to registration for women of childbearing potential; Adequate bone marrow, renal and hepatic function defined as follows:  Bone marrow: WBC > 3000 / mm3 (ANC > 1500 / mm3 ) Platelets > 100 000 / mm3. Hb > 10 gm/dl Renal: serum creatinine within institutional normal range(or) lower than the lower limit of institutional normal range : calculated creatinine clearance > 50 ml / min Hepatic: enzymes (SAP, SGOT) < 2x normal: bilirubin < 24 mol / l.  Exclusion Criteria:  Allergic to 18F-fluoromisonidazole or Nitroimidazoles Planned for neoadjuvant chemotherapy Uncontrolled hypercalcaemia: calcium 2.7 mmol/L (10.8 mg/dL). Other serious concomitant systemic disorders incompatible with the study (at the discretion of the investigator). Have serious active infection. Pregnant or lactating female subjects and subjects with reproductive potential not implementing adequate contraceptive measures