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目的分析CTVision进行鼻咽癌图像引导时采用不同的配准方式对摆位误差的影响。方法采用两种不同的图像配准方式,对同一个进行调强放射治疗的鼻咽癌患者采集得到的治疗CT图像与计划CT图像进行配准分析。自动配准:系统自动调节窗宽、窗位,进行图像灰度配准。骨性配准:手动调节基于第一颈椎体为骨性标志进行配准。配准得到的摆位误差大小以均数和标准差的形式表示。结果分别计算得到两种方法在X、Y、Z三个方向上的摆位误差数据,自动配准和骨性配准结果分别是X轴为(0.2286±0.1496)cm和(0.0571±0.0976)cm,Y轴为(-0.1000±0.1000)cm和(-0.0714±0.1254)cm,Z轴为(0.100 0±0.081 6)cm和(0.100 0±0.057 7)cm。两种配准方法比较,靶区在X轴上的摆位误差差异有统计学意义(P<0.05),而在Y轴和Z轴上差异均无统计学意义(P>0.05)。结论鼻咽癌进行图像引导时,基于骨性标志的手动配准和基于灰度的自动配准,在X轴方向的摆位误差校正差异明显,在Y轴和Z轴方向的无明显差异。采用骨性标志的配准是一种更为准确和有效的配准方式。
Objective To analyze the effect of different registration methods on the setup error of nasopharyngeal carcinoma images guided by CTVision. Methods Two different image registration methods were used to perform the registration analysis on the CT images and the planned CT images collected from the same NPC patients undergoing IMRT. Automatic registration: the system automatically adjust the window width, window level, the image grayscale registration. Bone registration: Manual adjustment is based on the registration of the first cervical vertebra for the bony signs. The size of registration error is shown as the mean and standard deviation. Results The setup errors of the two methods were calculated respectively in X, Y and Z directions. The results of auto-registration and bony registration were (0.2286 ± 0.1496) cm and (0.0571 ± 0.0976) cm (-0.1000 ± 0.1000) cm and (-0.0714 ± 0.1254) cm respectively on the Y axis and (0.100 ± 0.081 6) cm and (0.100 ± 0.057 7) cm on the Z axis. Compared with the two registration methods, there was a significant difference in the placement error of the target area on the X axis (P <0.05), but no significant difference in the Y axis and the Z axis (P> 0.05). Conclusion During the image guidance of nasopharyngeal carcinoma, manual registration based on bony markers and automatic registration based on grayscale have obvious differences in the error correction of X-axis positioning and no significant difference in Y-axis and Z-axis. Registration with bony signs is a more accurate and effective method of registration.