CBCT验证食管癌放射治疗中两种体位固定方式摆位误差的比较分析

目的:利用锥形束CT(CBCT)研究不同的体位固定方式对食管癌放射治疗时摆位准确性的影响.方法:随机选取30例食管癌患者分成2组(真空垫组,真空气垫+翼形板固定组),每组治疗时利用CBCT 进行扫描,共扫描150次,获取150组CT 数据,利用XVI 软件将CBCT 扫描图像与计划CT图像进行自动骨性配准,分别得出X、Y、Z共3个线性方向上的摆位误差值,对获得的2组数据进行比较,采用t检验比较数据差异有无统计学意义.结果:真空垫固定体位组摆位后行CBCT扫描,在X、Y、Z方向上进行配准所得的平均误差分别为:X方向(2.19±1.62) mm,Y方向(2.92±2.13) mm、Z方向(2.83±2.17) mm;而翼形板+真空垫固定组摆位后行CBCT扫描,在X、Y、Z方向上进行配准所得的平均误差分别为:X方向(1.89 ±0.83) mm、Y方向(2.33 ±1.29) mm、Z方向(1.54 ±0.93) mm.两组误差数据差异均有统计学意义(P<0.05).结论:翼形板联合真空垫固定体位技术更能减少食管癌放疗时的摆位误差,更能体现恶性肿瘤的"三精"放疗.

Comparison of the two kinds of immobilization of radiotherapy of esophageal carcinoma by CBCT

Objective:To evaluate the accuracy of different body immobilization methods of radiotherapy for esophageal carcinoma was studied by using the cone-beam CT(CBCT) method.Methods:A total number of 30 esophageal cancer patients were randomly assigned into 2 groups(vacuum pad group,wing panels+vacuum pads group) for immobilization,cone beam CT(CBCT) scan was adopted in each patients.XVI software to CBCT scan images and CT images were automatically registered.Setup errors of CBCT were calculated according to its matched and planned CT images in left-right(X),superior-inferior(Y) and anterior-posterior(Z) directions.Paired t-test was used to evaluate the differences.Results:In the vacuum pad group,the set-up errors of CBCT in the X,Y,Z axis were X(2.19±1.62) mm,Y(2.92±2.13) mm and Z(2.83±2.17) mm,respectively.In the wing panels + vacuum pads group,the set-up errors of CBCT in the X,Y,Z axis were X(1.89±0.83) mm,Y(2.33±1.29) mm and Z(1.54±0.93) mm,respectively.The difference between the two groups was statistically significant(P<0.05).Conclusion:The combination of the wing plate and the vacuum pad immobilization technique can further reduce the position error of esophageal carcinoma,and better reflect "three fine" radiotherapy.