光学体表影像系统联合开放式双面膜在头部肿瘤放疗中的应用

Application of optical surface imaging system combined with open double shell positioning system in radiotherapy of head tumor

目的比较光学体表成像系统Catalyst HD联合两种不同双面膜(DSPS)定位方式在头部肿瘤放疗中摆位精度的差异,探讨开放式双面膜临床使用的可行性。方法回顾性分析50例头部肿瘤放疗患者的摆位误差数据,根据双面膜类型分为封闭式双面膜组(C-DSPS)27例和开放式双面膜组(O-DSPS)23例。所有患者首次治疗获取真实参考床值,行锥形束CT(CBCT)验证并移床后获取体表参考图像;C-DSPS组的体表参考图像为全面部,O-DSPS组在头脚方向短于C-DSPS组,为双面膜开口长度,其余方向相同。通过CBCT图像与计划CT图像的刚性配准,获取床左右(X方向)、升降(Y方向)、进出(Z方向)、床旋转(Rtn)、进出倾斜(Pitch)、左右转动(Roll)的摆位误差并统计摆位时间。结果O-DSPS组和C-DSPS组Y方向的摆位误差分别为(0.05±0.05)cm、(0.07±0.05)cm,差异有统计学意义(P=0.03);Pitch方向的摆位误差分别为(0.61±0.41)°、(0.47±0.36)°,差异有统计学意义(P=0.01)。C-DSPS和O-DSPS两种方式的摆位时间分别为(53±17)s、(50±16)s,差异无统计学意义(P>0.05);两种摆位方式的异常摆位误差个数进行比较,所有方向的差异均无统计学意义(P>0.05)。结论开放式双面膜联合小体表方式各旋转方向误差略增大,但完全可接受,摆位时间未增加,实现了分次内误差实时监控,具有临床推广价值。

Objective To compare the setup accuracy of two different kinds of double shell positioning system(DSPS)positioned by optical surface imaging system of Catalyst HD in head tumor radiotherapy,and explore the feasibility of clinical use of open double shell positioning system.Methods The setup errors of 50 patients with head tumor radiotherapy were retrospectively analyzed.According to the type of double shell positioning system,they were 27 cases of closed double shell positioning system(C-DSPS)and 23 cases of open shell positioning system(O-DSPS).All patients were acquired the true reference couch values and body surface reference images after the first treatment verified by cone beam CT(CBCT).The body surface reference image of C-DSPS group was the full face,and the O-DSPS group was shorter than C-DSPS group in the head-foot orientation,which was the opening length of DSPS,while the other orientations were the same.Through the rigid registration of CBCT and planned CT images,the setup errors of six orientations(X,Y,Z,Rtn,Pitch,Roll)were obtained and the setup time was counted.Results The setup errors in Y direction in O-DSPS group and C-DSPS group were(0.05±0.05)cm and(0.07±0.05)cm,respectively,and the difference was statistically significant(P=0.03).The setup errors in pitch direction in O-DSPS group and C-DSPS group were(0.61±0.41)°and(0.47±0.36)°respectively,and the difference was statistically significant(P=0.01).The setup time of C-DSPS and O-DSPS were(53±17)s and(50±16)s respectively,and the difference was not statistically significant(P>0.05).There was no statistically significant difference in the count data of abnormal error(P>0.05).Conclusion The O-DSPS combined with small optical surface has slightly increased the errors of rotation orientation,but the setup time has not increased.It has realized the real-time monitoring of fractional internal error,and has the value of clinical promotion.