保护颈动脉鞘的局部晚期鼻咽癌IMRT计划对靶区及危及器官剂量的影响

Effects of carotid sheath-sparing intensity-modulated radiotherapy for locally advanced nasopharyngeal carcinoma on doses of target areas and organs-at-risk

目的:探讨保护颈动脉鞘的局部晚期鼻咽癌调强放疗(IMRT)计划对靶区及危及器官剂量的影响。方法:对10例局部晚期鼻咽癌患者行回顾性分析,分别设计常规IMRT计划及保护颈动脉鞘的IMRT计划。对PGTV_(nx)和PCTV_1的平均剂量(D_(mean))、D_(98%)、D_(50%)、D_(5%)、D_(2%)、适形度指数、均匀性指数,颈动脉鞘和危及器官剂量进行评价。结果:与常规IMRT计划相比,保护颈动脉鞘的IMRT计划中PGTV_(nx)的适形度指数、均匀性指数,PCTV_1的D_(50%)、D_(mean),颈动脉鞘的D_(max)、D_(mean),脊髓的D_(mean),以及脑干的V_(40)、D_(mean)均有所降低,有统计学差异(P<0.05);其它指标比较无统计学差异。结论:保护颈动脉鞘的局部晚期鼻咽癌IMRT计划能保证靶区剂量覆盖,降低颈动脉鞘和脑干的剂量,同时,计划的剂量分布也更为合理。

Objective To investigate the effects of carotid sheath-sparing intensity-modulated radiotherapy(IMRT)on the doses of target areas and organs-at-risk(OAR)in patients with locally advanced nasopharyngeal carcinoma(NPC).Methods A retrospective dosimetric analysis was performed on 10 patients with locally advanced NPC.Two plans,namely routine IMRT plan and carotid sheath-sparing IMRT plan,were designed for each patient.The mean dose(Dmean),D98%,D50%,D5%,D2%,conformity index and homogeneity index of planning gross target volume(PGTVnx)and planning clinical target volume(PCTV1)as well as the doses of the carotid sheath and OAR were evaluated.Results The conformity index and homogeneity index of PGTVnx,D50%and Dmeanof PCTV1,Dmax and Dmeanof carotid sheath,Dmeanof spinal cord,and V40 and Dmeanof brain stem in carotid sheath-sparing IMRT plan were significantly lower than those in routine IMRT plan,with statistical differences(P<0.05).No statistical differences were found in other dosimetric indexes.Conclusion Carotid sheath-sparing IMRT plan for locally advanced NPC can significantly reduce the doses of carotid sheath and brain stem without affecting target coverage,and achieve a superior dose distribution.