Basic principles
GTV: Including primary GTV (GTVp) and lymph node GTV (GTVn)	Description
No induction chemotherapy	Tumor range (primary tumor + lymph node) is shown by clinical examination (physical examination + nasopharyngoscopy + imaging).
Induction chemotherapy	The tumor area (primary tumor + lymph node) after induction chemotherapy, and the range of bone and paranasal sinus infiltration, are determined according to the range before induction chemotherapy.
Primary CTV
High‐risk CTVp1 (70 Gy)	GTVp + 5 mm (including the whole nasopharynx). When adjacent to important OAR, the distance can be reduced to 1 mm.
Medium risk CTVp2 (60 Gy)	GTVp + 10 mm When adjacent to an important OAR, the distance can be reduced to 2 mm.
Nasal cavity: posterior	At least 5 mm away from the posterior nostril.
Maxillary sinus: posterior	At least 5 mm away from the back wall.
Posterior ethmoid sinus	Including the vomer.
Skull base	Including the foramen ovale, foramen rotundum, foramen rupture, and apex.
Cavernous sinus	If the T stage is T3‐4 (including the affected side only).
Pterygoid fossa	All
Parapharyngeal space	All
Sphenoid sinus	T1‐2: Lower half; T3‐4: All.
Steep hill	If there is no invasion: First 1/3; if there is invasion: All.
Cervical lymph node CTV
High‐risk CTVn1 (70 Gy)	CTVn1 + 5 mm (if there is capsule invasion, it should be considered as 10 mm).
Medium risk CTVn2 (60 Gy)	CTVn1 + 10 mm.
Retropharyngeal, II, III, Va area	Both sides should be included, and the ipsilateral area should be at least one area lower than the invaded area.
Area VIIb	The upper boundary of region II lymph nodes should be extended upwards to reach the bottom surface of the skull, covering the space of the posterior styloid process to include the lymph node of the posterior styloid process.
Area Ib	The submandibular gland is involved, or tumors involve the anatomical structure of the drainage area of the lymph node with area Ib as the first station (the oral cavity and the anterior half of the nasal cavity). Invasion of area II lymph nodes with extracapsular invasion, or involvement of area II lymph nodes, with a maximum diameter of more than 2 cm, without extracapsular invasion.
Low‐risk CTVn3 (50 Gy)
Areas IV and Vb to the clavicle	If the ipsilateral cervical lymph nodes are not involved, areas IV and Vb may not be irradiated. Accordingly, if cervical lymph nodes are involved, ipsilateral areas IV and Vb need to be irradiated

Abbreviations: GTV, gross tumor volume; CTV, clinical target volume; OAR, organs at risk.