奥德热塑体模联合真空垫固定技术提高鼻咽癌放疗摆位精度的分析

摘要

目的：应用锥束计算机体层摄影术（CBCT）评估热塑体模加真空垫固定技术在鼻咽癌放疗中的作用，以期寻找最优的固定辅助装置，减少摆位误差，提高治疗精度。方法选取60例行调强放射治疗的鼻咽癌患者，随机分为热塑体模组（n=30）和热塑体模+真空垫组（n=30），两组患者均在放疗第一周每天1次，此后每周进行1次图像引导放射治疗。治疗过程中用实时图像与定位CT图像进行自动灰度配准，计算出当前患者在X、Y、Z轴方向的误差。结果在治疗第1、第2周，热塑体模+真空垫组患者X轴误差绝对值均明显小于热塑体模组，差异有统计学意义（P﹤0.01）；而在第3、第4周两组X轴误差绝对值比较，差异均无统计学意义（P﹥0.05）；两组间Y轴和Z轴误差绝对值在各时间点比较，差异均无统计学意义（P﹥0.05）；随时间的推移，热塑体模+真空垫组X轴上的误差不断升高，而热塑体模组X轴上误差不断降低。结论热塑体模加真空垫固定技术能够有效减少放疗过程中的摆位误差，有助于提高放疗的精确性。%Objective To investigate the combined utilization of thermoplastic film plus vacuum mold in radiothera-py for patient with nasopharyngeal carcinoma using cone beam computed tomography (CBCT), in order to find the opti-mal auxiliary fixing device to reduce setup errors and improve therapeutic accuracy. Method Sixty patients with naso-pharyngeal carcinoma treated with IMRT were randomized as control group (n=30) and study group (n=30), applied with thermoplastic film alone, or with thermoplastic film plus vacuum mold, respectively. All patients were treated with IGRT every week during radiotherapy. The positioning errors in X-, Y-, and Z-axis were obtained using automatic gray level reg-istration through comparing real time piece and CT image. The setup error was corrected automatically with automatic po-sition. Result In the 1st and 2nd week of treatment cycle, the absolute setup error in X-axis of study group was significant lower than that in control group (P<0.01);While in the 3rd and 4th week, the difference in X-axis turned insignificant (P>0.05);The absolute setup error of Y-and Z-axis in the two groups were of no significant difference at all time points (P>0.05);As time elapsed, the setup error in X-axis was increased in study group, while that of control group was decreased. Conclusion Thermoplastic film plus vacuum mold can effectively reduce the setup errors during radiotherapy, and im-prove the accuracy and precision of radiotherapy.