Inclusion Criteria:

- Histologically confirmed squamous cell carcinoma of the oral cavity, oropharynx,
hypopharynx or larynx.

- Primary unresectable tumor and/or patients refused surgery.

- Stage T1-4; T3-4 N0 or Tany N1-3 for cancer of the glottis.

- Multidisciplinary decision of curative radiotherapy or radiochemotherapy.

- Karnofsky performance status ≥70%.

- Age ≥ 18 years old.

- Informed consent obtained, signed and dated before specific protocol procedures.

Exclusion Criteria:

- Treatment combined with brachytherapy.

- Prior irradiation to the head and neck region.

- Distant metastases.

- Second primary tumors that are not under control

- Pregnant or lactating women.

- Creatinine clearance (Cockcroft-Gault) ≤ 60 mL/min before treatment.

- Allergy to the CT-contrast agents.

- Mental condition rendering the patient unable to understand the nature, scope, and
possible consequences of the study.

- Patient unlikely to comply with protocol, i.e. uncooperative attitude, inability to
return for follow-up visits, and unlikely to complete the study.