胸上段食管癌SIB-IMRT治疗不同射野角度的剂量学比较

Dosimetric comparison in SIB-IMRT with 5-field for upper thoracic esophageal carcinoma

目的:比较胸上段食管癌同步加量放疗不同射野角度调强计划的靶区和危及器官的剂量学差异。方法:选择20例食管癌患者,每例患者设计两组5野调强计划,A组:5野均分,射野角度为216°,288°,0°,72°和144°;B组:射野角度为200°,300°,0°,50°,150°。比较两组计划的靶区剂量分布和危及器官的剂量学差异。结果:A组调强计划的PCTV均匀指数(HI)和适形指数(CI)均优于B组调强计划,差异有统计学意义(P<0.05);B组调强计划的双肺V5,V10,V20均低于A组调强计划,心脏的V30、V40及脊髓的Dmax均大于A组,差异有统计学意义(P <0.05),两组计划的PGTV和双肺的V30差异无统计学意义(P> 0.05)。结论:B组调强计划虽然没有A组调强计划的靶区适形度高,但是在减少肺部低剂量照射体积方面更具有优势,可以满足临床上大多数情况的要求。

Objective To compare the dosimetric differences in IMRT plans with 5-field in the treatment of simultaneous integrated boost for upper thoracic esophageal carcinoma.Methods For 20 patients with upper thoracic esophageal were involved in this study.Two IMRT plans with 5-field were designed for each patient.Plan A:The fields were equispaced,including 216°,288°,0°,72°and 144°;Plan B:The fields were optimized,including 200°,300°,0°,50°and 150°.The difference of dose distribution to target and organs at risk was compared.Results PCTV Conformity Index(CI)and Homogeneity Index(HI)of plan A was better than that of plan B(P<0.05).However,the double lung V5,V10 and V20 of plan B were significantly lower than those plan A(P<0.05).In addition,the heart V30,V40 and spinal cord Dmax of plan B were significantly higher than those of plan A(P<0.05).There was no significant dosimetric different in PGTV and lung V30 between those two plans(P>0.05).Conclusions Although the conformity of plan B is no better than that of plan A,the volume of double lungs received lower irradiated dose significantly decreases when compared with plan A.IMRT plan B can meet clinical requirements in most situations.