Table 4.

Target volumes used in the study by Yang et al. (64).

Target/Group	Group A (pre-induction)	Group B (post induction)
Imaging timing	Pre-induction CT and MR	CT and MR at day 14, cycle 2 of induction (cisplatin + paclitaxel or 5-FU)
Pre-IC GTVnx	Clinical + imaging findings pre-IC;	Clinical + imaging findings pre-IC;
Post-IC GTVnx	N/A	Clinical + imaging findings post-IC;
GTVnx (includes primary and retropharyngeal nodes)	Pre-IC GTVnx	Post-IC GTVnx
P-GTVnx dose (GTVnx +3–5 mm)	70Gy/33#	70Gy/33#
CTV1 (subclinical disease)	Pre-IC GTVnx + 0.5–1 cm margin Whole nasopharyngeal wall 0.5cm margin under normal pharyngeal mucosa	Post-IC GTVnx + 0.5–1 cm margin Pre-IC GTVnx Whole nasopharyngeal wall 0.5 cm margin under normal pharyngeal mucosa
P-CTV1 dose (CTV1 + 3–5 mm)	64Gy/33#	64Gy/33#
GTVnd	Clinical + imaging findings of gross nodal disease post-IC Pre-IC ECE was assessed and included based in pre-IC imaging	Clinical + imaging findings of gross nodal disease post-IC Pre-IC ECE was assessed and included based in pre-IC imaging
P-GTVnd dose (GTVnd +3–5 mm)	70Gy/33#	70Gy/33#
CTV2	Pre-IC CTV1 Posterior nasal cavity Posterior maxillary sinus Pterygopalatine fossa Part of posterior ethmoid sinus Parapharyngeal space Skull base Clivus (whole/partial depending on involvement)	Post-IC CTV1 Posterior nasal cavity Posterior maxillary sinus Pterygopalatine fossa Part of posterior ethmoid sinus Parapharyngeal space Skull base Clivus (whole/partial depending on involvement)
Pre-IC CTV2	Elective nodal irradiation	Elective nodal irradiation
P-CTV2 (CTV2 + 3-5mm)	54Gy/33#	54Gy/33#

CT, computed tomography; MR, magnetic resonance imaging; 5-FU, 5-Fluorouracil; IC- induction chemotherapy; GTVnx, nasopharynx gross tumor volume; P-GTV-nx, high dose primary planning target volume; CTV, clinical planning volume; P-CTV –planning target volume based on CTV; GTVnd, nodal gross tumor volume; P-GTVnd, high dose nodal planning target volume.