Delineating target volume
tumor, primary tumors, palate
TUMOR, METASTASIS, PRIMARY TUMORS, INNER EAR, OPTIC NERVE, NASOPHARYNGEAL CARCINOMA, LENS, PRIMARY TUMOR
Gross tumor volume of nasopharyngeal carcinoma (GTVnx) refers to the area of primary tumors in the nasopharynx observed in clinical practice and various imaging studies. Gross tumor volume of cervical node (GTVnd) refers to the area of enlarged lymph nodes observed in clinical practice and/or imaging studies. The clinical target volume (CTV) range is mainly divided into high‐ and low‐risk areas according to the local progression of NPC. Clinical target volume 1 (CTV1) is defined as the adjacent area around a primary tumor that is very likely to be invaded by the tumor or the area to which the tumor is very likely to metastasize. Clinical target volume 2 (CTV2) is defined as a lymph node region with possible metastasis deduced from the biological behavior of a tumor, including the cervical lymphatic drainage area without metastatic lymph nodes.Organs at risk (OAR) should be delineated by including the brainstem, cervical spinal cord, temporal lobe, optic nerve, optic chiasm, pituitary gland, lens, temporomandibular joint, mandible, inner ear, and parotid gland.Oral delineation ranged from the hard palate to the floor of the mouth, from the buccal mucosa around the teeth to the lingual surface and uvula.