DVH评价食管癌适形放疗计划对肺的影响

[目的]了解不同食管癌适形放疗计划对肺的影响。[方法]选择7例胸段食管癌病例,用ACQPLAN系统进行CT模拟定位并设计不同适形放疗计划,用剂量体积组方图(DVH)指标进行对比。每一例均设计三野(一前、二后斜)、四野(二前斜、二后斜)和六野(四野加一前一后野),对比以上不同计划中全肺平均接受剂量(Dmean)和受量超过20Gy的肺体积(V20Gy)。[结果]三野和六野计划的肺Dmean较接近,均明显低于四野计划的Dmean(P<0.01);三野计划的V20Gy明显低于四野和六野计划的V20Gy(P<0.01)。三个计划中所有病人的脊髓受照射剂量均在45Gy以下。[结论]综合考虑对脊髓和肺的影响,三野计划为食管癌适形放疗的较优方案。

The Impact of Conformal Radiotherapy on Lung in Patients with Esophageal Carcinoma--An Evaluation of Dose-volume Histogram(DVH)

To investigate the impact of conformal radiotherapy on the lung in patients with esophageal carcinoma.Seven cases of thoracic esophageal carcinoma were selected for the study.All cases were re-ceived CT simulation with ACQPLAN system.Three conformal radiotherapy schemes were planned for each patient.The three beam scheme including one anterior and two posterior oblique beams,four beam scheme including two an-terior oblique and two posterior oblique beams;six beam scheme including one anterior and one posterior beams plus4beams as the same of four beam scheme.The effect of mean dose for whole lung(D mean )and the proportion for lung receiving at least20Gy(V 20Gy )were compared.The three beam scheme and six beam scheme have significant lower D mean than four beam scheme(P<0.01).The V 20Gy of three beam scheme is significant lower than that of four beam scheme and six beam scheme(P<0.01).The distribution dosage of the spinal cords in the three schemes were all lower than45Gy.[Conclusions]Three beam scheme is the optimal choice of conformal radiotherapy plan for esophageal carcinoma as concerning the dose distribution to lung and spinal cord.