调强放疗保护N_0鼻咽癌患者颌下腺的研究

目的：探讨调强放疗保护N0鼻咽癌患者颌下腺的可行性。方法：选择N0鼻咽癌患者10例,对每个病例分别制定保护颌下腺的调强放疗计划（计划A）和不保护颌下腺的调强放疗计划（计划B）,比较两种计划的颌下腺、靶区和正常组织/危及器官的剂量分布、剂量体积直方图（DVH）等指标。结果：计划A和计划B相比,前者明显降低了颌下腺的照射剂量：左侧颌下腺D50分别为50.88Gy和30.96Gy,降低了19.92Gy（39.15%）,D平均分别为50.27Gy和31.16Gy,降低了19.11Gy（38.01%）;右侧颌下腺D50分别为50.71Gy和31.27Gy,降低了19.44Gy（38.34%）,D平均分别为49.79Gy和31.73Gy,降低了18.06Gy（36.27%）。两种计划中靶区剂量无明显差别：GTV的D99分别为67.29Gy和67.62Gy,GTV的D95分别为69.59Gy和69.22Gy,GTV的D1分别为73.64Gy和73.64Gy,GTV的Daverage分别为71.21Gy和70.92Gy,GTV的Dmin分别为66.95Gy和66.79Gy;CTV1的D95分别为63.12Gy和63.32Gy,CTV1的Daverage分别为67.62Gy和67.29Gy,CTV1的Dmin分别为56.94Gy和56.45Gy;CTV2的D95分别为54.35Gy和54.65Gy,CTV2的Daverage分别为61.03Gy和60.83Gy,CTV2的Dmin分别为42.62Gy和42.72Gy。脑干的D1和D5、脊髓的D1、颞叶D5、颞颌关节的D50、腮腺的D50及D平均剂量两种计划比较差别不明显。结论：利用调强放疗可以安全有效地保护N0鼻咽癌患者的颌下腺,从而有可能进一步降低患者的口干症状。

Sparing the submandibular glands by intensity modulated radiotherapy in the treatment of N_0 neck nasopharyngeal carcinoma

Objective：To explore the feasibility of sparing the submandibular glands by intensity modulated radiotherapy in the treatment of N0 neck nasopharyngeal carcinoma.Methods：Ten patients with N0 neck nasopharyngeal carcinoma were selected.Two IMRT plans were designed for each patient.Plan A：sparing submandibular glands;Plan B：non-sparing submandibular glands.The dose distribution and dose volume histograph（DVH） of submandibular glands ,target and organs at risk（OAR） of two IMRT plans were compared.Results：The D50 to the left submandibular gland were 50.88Gy and 30.96Gy respectively in the plan A and plan B and to the right submandibular gland were 50.71Gy and 31.27Gy respectively.The arerage dose to the left submandibular gland were 50.27Gy and 31.16Gy respectively in the plan A and plan B and the right submandibular gland were 49.79Gy and 31.73Gy respectively.Plan A showed 39.15% and 38.34% decrease of D50 to the left and right submandibular gland and 38.01% and 36.27% decrease of arerage dose to the left and right submandibular gland.There were little difference in target＇s D99,D95,D1,Daverage and Dmin.Also there were little difference in the D1/D5/D50/Daverage of organs at risk（OAR）.Conclusion：Submandibular gland sparing with IMRT is safe and effective in the treatment of N0 neck nasopharyngeal carcinoma and decrease the degree of radiation-associated xerostomia.