胸段食管癌常规采用三野照射法 (前一野 ,后二斜野 ) ,因两后斜野避开脊髓 ,使放射性脊髓炎的发病率明显减少。但两后斜野射线束通过低密度的肺组织 ,使靶区剂量增加 ,有可能出现放射性肺炎的危险 ,为了准确地估算肺组织对食管癌放疗靶区的影响 ,本文分析了 4 2例胸中段食管癌 Thoracic esophageal cancer routine use of three field irradiation (the former field, after the second field), due to the two posterior field to avoid the spinal cord, the incidence of radiation-induced myelitis was significantly reduced. However, the two posterior oblique beam through the low-density lung tissue, the target dose increases, there may be the risk of radiation pneumonitis, in order to accurately estimate the impact of lung tissue on the esophageal cancer radiotherapy target area, the paper analyzed 42 cases of chest Middle esophageal cancer