热塑体膜联合真空垫在肺癌放疗中的应用

Application of thermoplastic phantom with vacuum pad in radiotherapy of lung cancers

摘要:

目的 分析热塑体膜联合真空垫在肺癌放疗中的临床应用价值。方法 将26 例肺癌调强放射治疗 （IMRT）患者随机分为两组，常规组采用胸部热塑体膜固定，改进组采用热塑体膜联合真空垫固定。治疗过 程通过锥形束CT 图像引导系统（CBCT）测量摆位数据，与参考图像对比分析。采用二参数法计算由内靶 体积（ITV）外扩产生计划靶体积（PTV）间距。结果 常规组与改进组比较，在X、Y、Z 3 个方向的偏移误差 为（2.63±1.53）/（2.26±0.95）mm，（2.39±1.36）/（1.53±1.16）mm，（3.26±2.17）/（2.13±1.14）mm，差异均 有统计学意义（P <0.05）；常规组ITV 外放PTV 范围在X 、Y 、Z 轴方向依次为6.33、5.73 和8.04 mm，改进 组ITV 外放PTV 范围在X 、Y 、Z 轴方向依次为5.19、3.87 和5.06 mm。结论 热塑体膜联合真空垫可以更小 的减小摆位误差，提高肺癌放疗体位的准确性和重复性。

Abstract:

Objective To analyze the clinical value of thermoplastic phantom with vacuum pad in radiotherapy of lung cancers. Methods Twenty-six cases of lung cancer patients treated with IMRT were randomly divided into two groups. In the conventional group thermoplastic phantom was used for fixation, in the improvement group thermoplastic phantom and vacuum pad were fixation. A two-parameter method was used to calculate the distance of planned target volume (PTV) extended from the internal target volume (ITV). Cone beam CT (CBCT) was used to measure positioning data through the course of treatment, and the data were analyzed with the DRR images. Results In the conventional group and the improvement group, the set-up errors in X, Y and Z directions were (2.63 ± 1.53) mm and (2.26 ± 0.95) mm (P < 0.05), (2.39 ± 1.36) mm and (1.53 ± 1.16) mm (P < 0.05), (3.26 ± 2.17) mm and (2.13 ± 1.14) mm (P < 0.05) respectively. The PTV ranges from ITV in the directions of X, Y and Z axes were 6.33, 5.73 and 8.04 mm in the conventional group and 5.19, 3.87 and 5.06 mm in the improvement group. Conclusions Combined use of thermoplastic phantom and vacuum pad can better reduce positioning errors, and improve position accuracy and repeatability in lung cancer radiotherapy.