胸段食管癌术后预防照射三维适形放疗与常规放疗剂量学比较

Comparison of dose distribution between 3-DCRT and conventional radiotherapy in postoperative radiotherapy for thoracic esophageal carcinoma

目的:比较胸段食管癌术后预防照射三维适形放疗与常规放疗时的剂量分布特点以指导临床应用。方法:采用统一体位自身对照的方法,以三维治疗计划中体积剂量分布图(DVH)和等剂量曲线为评价标准,观察10例胸段食管癌术后预防照射患者分别在三维适形放疗和常规放疗56Gy时,靶区和正常组织的剂量分布情况。结果:靶区剂量95%PTV三维适形放疗组56Gy高于常规放疗组35.6Gy(P<0.05)。达到56Gy的PTV体积三维适形放疗组为95%,高于常规放疗组51.5%(P<0.05)。心脏V40、V50三维适形放疗组为26.5%、5.9%,低于常规放疗组47.7%、30.4%(P<0.05)。双肺V20三维适形放疗组为23.8%,高于常规放疗组7.8%(P<0.05)。脊髓最大照射剂量三维适形放疗组和常规放疗组分别为43.5Gy和44.5Gy(P>0.05)。残胃V40、V50及最大剂量两组无显著差别(P>0.05)。结论:在胸段食管癌术后预防照射中,三维适形放疗比常规放疗在保证靶区剂量上有明显优势,并使心脏损伤风险显著降低。在脊髓和残胃的剂量分布无明显差异。对双肺V20则提高较明显,临床应予以重视。

Objective：To compare the dose distribution between 3-DCRT and conventional radiotherapy in the preventive radiotherapy of the thoracic esophageal cancer after operation.Methods：By the same body position and self control,with the dose-volume histograms and isodose curve in 3-DCRT program as standard,the dose distribution of target and normal tissue in ten postoperative patients with thoracic esophageal carcinoma at the dose of 56Gy was observed.Results：When the doseage of the 95%PTV in 3-DCRT group was 56Gy,which in conventional group was 35.6Gy（P〈0.05）.The volume of PTV which reached 56Gy in 3-DCRT group was 95%,in conventional group was 51.5%（P〈0.05）.The V40,V50 of heart in 3-DCRT group were 26.5%,5.9%,in conventional group were 47.7%,30.4%,respectively（P〈0.05）.The V20 of both lung in 3-DCRT group was 23.8%,in conventional group was 7.8%（P〈0.05）.The spinal cord in 3-DCRT group and conventional group were separately 43.5 Gy and 44.5Gy（P〉0.05）.The V40,V50 and maximum dose of remnant stomach had no difference in the two groups,respectively（P〉0.05）.Conclusion：With the preventive radiotherapy of the thoracic esophageal cancer after operation,there are some differences between 3-DCRT and conventional radiotherapy.It has better dose distribution in target area and lower damage in heart.It has no different in spinal cord and remnant stomach on dose distribution,but it can increase the V20 of the lung.and we should pay attention to the clinical application.