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目的证明ＣＴ扫描所示肿瘤大小的准确性，依此以肿瘤为射野中心，采用合理的照射野。方法１９９３年１２月至１９９６年１２月７７例疗前有病理诊断和ＣＴ扫描的食管癌病人。取３个层面，绘制并测量相应照射野的大小及正常组织的受量。结果（１）ＣＴ所示肿瘤的大小与手术标本比较Ｐ＞０．０５。放射治疗组的肿瘤各径线均大于手术组。（２）肿瘤为非对称性浸润，以管腔为射野中心，经典的照射野大小（前宽６．０ｃｍ，后斜野５．０ｃｍ），≥３５．１％的病人８０％～９０％的等剂量曲线不能包全肿瘤。如以肿瘤为射野中心，前野宽７．０ｃｍ，两后斜野为６．０ｃｍ，８０．７％的病人８０％～９０％的等剂量曲线包全肿瘤且剂量分布均匀。如肿瘤直经＞５．１ｃｍ，先前后对穿野而后分野照射。（３）采用剂量—容积百分比直方图，５０％，２０％肺最大受量体积分别为１８％，４９％。临床上该剂量很少发生急性放射性肺炎。结论（１）证实了食管癌ＣＴ扫描的准确性和可靠性，应列为放射治疗前常规检查方法之一。（２）定位应以肿瘤为中心，确保８０％～９０％的等剂量曲线包全肿瘤。（３）应据ＣＴ所示肿瘤大小，外侵形状，灵活选择照射野。
Objective To prove the accuracy of the tumor size as shown on the CT scan, so that the tumor is the center of the field and a reasonable radiation field is used. Methods From December 1993 to December 1996, 77 patients with esophageal cancer who had pathological diagnosis and CT scan before treatment. Take three levels, draw and measure the size of the corresponding field and the amount of normal tissue. Results (1) The size of the tumor as compared with the surgical specimen P>0.05. The diameters of the tumors in the radiotherapy group were larger than those in the surgery group. (2) The tumor is asymmetrically infiltrated, with the lumen as the center of the field, the size of the classic field (6.0cm in front, 5.0cm in posterior oblique field), 80% to 90% of patients with ≥35.1% The isodose curve does not cover the entire tumor. If the tumor is the center of the field, the width of the front field is 7.0cm, and the back oblique field is 6.0cm. 80.7% of the patients have an 80% to 90% isodose curve to cover the entire tumor and have a uniform dose distribution. If the tumour is more than 5.1cm in diameter, it will be followed by a field-clearing afterwards. (3) Using the dose-volume percentage histogram, the volume of 50% and 20% of the maximum lung volume were 18% and 49%, respectively. Acute radiation pneumonitis rarely occurs clinically at this dose. Conclusions (1) The accuracy and reliability of CT scanning of esophageal cancer were confirmed and should be listed as one of the routine examinations before radiotherapy. (2) The orientation should be centered on the tumor to ensure that an 80% to 90% isodose curve encompasses the entire tumor. (3) According to the size of the tumor as indicated by CT, the shape of the external invasion should be selected flexibly.