Background and purpose: Head and neck lymphedema (HNL) is a common side effect of intensitymodulated (IMRT) radiotherapy for nasopharyngeal carcinoma (NPC)

but few studies have been reported. The purpose of this study was to explore a method to prevent or mitigate HNL after radiotherapy for NPC patients and to study its dosimetric feasibility. Methods: Two groups of plans were designed for 20 NPC patients. Plan A included simplified intensity-modulated radiotherapy (sIMRT) plans by conventional method

and plan B included sIMRT plans using the anterior head and neck lymphatic drainage protection area. Dose distributions of the target

dose-volume parameters of organs at risk (OAR) and the total monitor units (MU) were compared between the two groups. Results: The target dose distributions of the two groups all met the clinical requirements. The indicators of planning target volume 1 (PTV1) had no significant difference between the two groups. In plan A

D

98%

V

100%

(%)

V

95%

(%) and homogeneity index (HI) of PTV2 were superior to those in plan B (t=4.134

3.455

2.423 and -2.410

P0.05). D

mean

of left and right parotid gland and V

30

of left parotid gland in plan A were lower than those in plan B (t =-2.454

-2.113 and -4.651

P0.05). For oral cavity

D

mean

and V50 were higher in plan A (t=4.639 and 2.237

P0.05). Similarly

D

mean

and V

50

of larynx were also higher in plan A (t=10.934 and 4.624

P0.05). Compared with plan A

the total MU of plan B increased slightly

but the differences were not statistically significant. Conclusion: The plan design of the anterior head and neck lymphatic drainage protection is feasible in dosimetry for NPC patients. Without sacrificing the target coverage

a low-dose (20 Gy) lymphatic drainage area can be reserved to the front of head and neck while oral cavity and larynx are better protected.