肺癌立体定向放射治疗中两种固定技术摆位误差的比较研究

Analysis of setup errors in stereotactic body radiotherapy for lung cancer using two immobilization devices

目的:比较分析在立体定向放射治疗中使用热塑体模和负压真空垫两种体位固定方式治疗肺癌患者分次间的摆位误差,并比较两种摆位的时间。方法:回顾性分析2015年1月至2016年11月间浙江省肿瘤医院121例体部立体定向放射治疗的肺癌患者,分为热塑体模组(A组)43例,真空负压垫组(B组)78例。在每次治疗之前使用锥形束CT(cone-beam CT,CBCT)进行扫描,再进行手动配准得出患者左右(X轴)、上下(Y轴)、前后(Z轴)方向的摆位误差,比较两组的摆位误差大小,并记录其摆位时间。结果:A组和B组X方向的摆位误差分别为0.16 0.09/0.25 0.11 cm,(P<0.05),在Y轴方向摆位误差分别为0.27 0.13/0.25 0.15 cm,(P>0.05),在Z轴方向的摆位误差分别为0.19 0.13/0.26 0.12 cm,(P<0.05),A组和B组平均摆位时间分别为57.66 s/58.09 s,(P>0.05)。结论:在X轴和Z轴方向上A组优于B组,在Y轴方向上无明显差异,A组摆位时间低于B组。在使用立体定向放射治疗治疗肺癌患者时在不考虑患者年龄、心肺功能时热塑体模无疑是最好的固定方式。

Objective：To compare the differences in interfraction setup accuracy and setup time between lung cancer patients treated with stereotactic body radiotherapy using thermoplastic masks and vacuum cushion system. Methods：A retrospective study was per-formed on 121 patients during January 2015 to November 2016 and included thermoplastic fixation mask for 43 cases and vacuum fix-ation cushion for 78 cases. Before irradiation, a kilovoltage cone-beam computed tomography （KV-CBCT） scan was performed and im-age registration was done automatically and manually to obtain setup errors from the X, Y, and Z axes. The differences of setup errors between the two immobilization methods were analyzed and the setup time was recorded. Result：The setup errors for thermoplastic masks and vacuum cushion in the X, Y, and Z axes were （0.16 ± 0.09 versus 0.25 ± 0.11） cm （P〈0.05）, （0.27 ± 0.13 versus 0.25 ± 0.15） cm （P〉0.05）, and （0.19 ± 0.13 versus 0.26 ± 0.12） cm （P〈0.05）, respectively. The setup time for thermoplastic masks and vacuum cush-ion were （57.66 versus 58.09） s （P〉0.05）. Conclusion：Thermoplastic masks offer better reproducibility and significantly less interfrac-tional setup displacement than vacuum cushions in the X and Z axes. No significant difference was found in the Y axis. Moreover, the setup time of thermoplastic masks is less than vacuum cushions. The thermoplastic mask is the best choice if the age and cardio-pul-monary function of patients can be ignored.