The investigators tries a new method to delineating the oral cavity, oropharynx, larynx and hypopharynx, and use the head-and-neck region to test whether the method can to create a good IMRT plan, and alleviate the oral radiation injury, reduce the incidence of adverse reactions.

Purpose: To assess the dosimetric effect of new delineation approach for oral cavity, oropharynx, larynx and hypopharynx in intensity-modulated radiotherapy(IMRT) treatment planning for head and neck cancer.

Methods: Twenty head and neck cancer patients were treated by IMRT. Target volumes and several organs at risk were delineated with Corvus6．3 treatment planning system. An investigative IMRT plan was generated based on a standard treatment planning protocol, but used a new delineation approach for oral cavity, oropharynx, larynx and hypopharynx. Plans were exported to treatment planning system for quantitative analysis of dose volume parameters. Variables assessed included: maximum oral cavity, oropharynx, larynx and hypopharynx dose, equivalent uniform dose of the oral cavity, oropharynx, larynx and hypopharynx (EUD), mean oral cavity, oropharynx, larynx and hypopharynx dose, mean organs at risks (OARs) doses, and dose homogeneity inside the target volumes.

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Inclusion Criteria:

- patients with previously untreated of the head and neck cancer who received definitive IMRT at our institution

Exclusion Criteria:

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