To Evaluate the Efficacy and Feasibility of Modified Reduce-volume Target IMRT in the Treatment of Patients With Non-metastatic NPC

The gross tumor volume of the nasopharynx and neck nodes (GTVnx and GTVnd) were delineated according to the tumor extension. The CTVnx was defined as GTVnx + nasopharynx mucosa + 8mm +corresponding anatomical structure without the delineation of CTV1. The CTVnd was defined as GTVnd plus the elective neck area. The prescribe doses of GTVnx/GTVnd, CTVnx, CTVnd were 66-70Gy,54-56Gy and 50-54Gy in 31-35 fractions, respectively.