CT-on-rail图像引导技术在肺癌放疗中的应用

The application of IGRT based on CT-on-rail system in lung cancer

目的比较滑轨CT(CT-on-rail)和电子射野影像系统(EPID)两种图像引导放射治疗(IGRT)技术在肺癌放疗中的应用,并比较不同图像匹配方式对放疗摆位精度的影响。方法对16例肺癌患者在放疗期间每周行1次EPID和CT扫描并进行图像配准,得出X、Y、Z 3个线性方向的误差值,进行统计学分析,对2种IGRT方法进行比较;滑轨CT组分别有灰度、轮廓和骨性标志模式,观察3种配准方式对摆位精度的影响。结果 CT和EPID配准的X、Y、Z三维方向差异均有统计学意义(P<0.05)。CT配准组中通过3种配准方法得出,X轴、Z轴图像匹配采用灰度模式比轮廓和骨性标志模式精度高,差异有统计学意义(P<0.05);Y轴上灰度模式和轮廓模式精度高于骨性标志模式,差异有统计学意义(P<0.05)。结论基于CT-on-rail系统进行的图像引导放射治疗比基于EPID系统进行的图像引导放射治疗精度高;在使用滑轨CT进行肺癌图像引导放疗时,建议首选灰度模式配准。

Objective To compare the application of CT-on-rail system and EPID of radiotherapy in lung cancer and to explore the effects of different matching models on positioning precision. Methods 16 patients with lung cancer were recruited in this study. Each patient received IGRT based on CT-on-rail system and EPID each week, respectively. Compared the difference of set -up errors between two groups. Besides, the group of CT-on-rail sys- tem included grey- scale model, bone model and outline model, and the difference among them were compared. Results There was significant difference between the average set - up errors of EPID and CT-on-rail system in the direction of X, Y and Z axis（P 〈 0.05）. In the lung cancer patients treated using CT-on-rail system, image matc- hing using grey - scale model precise in the direction of X and Z axis （ P 〈 0.05 ） , while grey-scale and outline model precise in the direction of Y axis（P 〈 0.05）. Conclusion CT-on-rail system is better than EPID in detec- ting set - up error of the lung cancer patient. Grey-scale model should be applied in the image matching of IGRT in lung cancer.