Alternative technique reducing the dose inhomogeneity related to fields matching for head and neck cancer and tolerance of organ at risk

We investigate the ability of One Point-Setup Multi-Segment technique (1PS-MST) to avoid electron beams and fields Matching, and to reduce the volume of Organ at Risk (OARs: spinal cord, left and right parotid glands (LPG and RPG), brainstem and ARiasma) irradiated in Head and Neck (H&N) cancer patients. This is for situations where the Inverse-Planned Intensity-Modulated Radiation Therapy (IP-IMRT) is not available in medical clinic, or for patients who are not suitable for IP-IMRT. Moreover, to allow a higher accuracy of patient positioning, we also compare the 1PS-MST with the Mono-Isocentric Conventional Technique (MICT) according to the homogeneity and conformity of the planning target volume dose and the OARs's dose volume histograms (DVHs) for 13 patients with different clinical pathologies (nasopharynx, larynx, hypopharynx and oral cavity).