Objective:To compare the dosimetric advantages of intensity -modulated radiation therapy(IMRT)to three -dimensional conformal radiotherapy(3D -CRT)in patients with up /middle -thoracic esophageal cancer after resection.Methods:Using the same TPS of CMS,ten patients with up /middle -thoracic esophageal cancer after re-section,postoperative pathology of T3 /T4 and /or lymph node -positive were enrolled.Both 3D -CRT plan and a five-field IMRT plan were generated with target 54Gy/27f irradiation.The parameters of dose volume histogram for tar-gets and organs at risk and conformity index(CI)were compared between two techniques.Results:In the same dose of target mode ,the dose distribution of isodose (95%CTV,95%PTV and 100%PTV)and conformity index(0.93 vs 0.79)of sIMRT plan were better than 3D -CRT plan with approximately consistent dose in the normal tissues (lung,spinal cord,stomach and other organs)in all ten cases.Conclusion:The target area dose distribution in IMRT was superior than 3D -CRT in postoperative adjuvant treatment of patients with up /middle -thoracic esophageal cancer.%目的：比较在胸部上中段食管癌术后预防性放射治疗中调强放射治疗（IMRT）与三维适形放射治疗（3D －CRT）剂量分布差异。方法：采用 CMS 治疗计划系统，对10例胸部上中段食管癌术后病理为 T3／T4和／或淋巴结阳性患者分别设定3D －CRT 54Gy／27f 照射和 IMRT 54Gy／27f 照射，比较两者相关靶区和危及器官的剂量体积直方图参数及靶区适形指数（CI）。结果：在相同靶区相同剂量模式下，10例患者在肺、脊髓、胃等组织器官受量近似一致的情况下，IMRT 等剂量线的剂量分布（95％CTV、95％PTV 和100％PTV）及靶区适形指数（CI）（0．93 vs 0．79）均优于3D －CRT。结论：相同靶区相同剂量模式下，胸部上中段食管癌术后预防性照射治疗时，调强放疗技术（IMRT）靶区剂量分布优于三维适形放疗（3D －CRT）。
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