空间配准是计算机辅助骨科手术的关键步骤，配准精度直接影响导航效果。本文针对基于二维图像的视觉配准方法，通过理论分析和计算机仿真，研究该方法常用的双平面定位标尺标记点分布拓扑对定位精度的影响，得到了标记点间距、数目等因素对定位精度的影响规律，给出了定位误差在空间上的分布特点。研究表明，增加标记点的数目和间距有助于减小定位误差；并且，在包络外接圆半径相等时，五点四边形的分布拓扑方式较四点矩形和四点三角形更优。
The registration is a critical step in the computer assisted orthopaedic surgery (CAOS). The accuracy of the registration directly affects the effect of the navigation. In this paper, the influence of the fiducials configuration on the accuracy of the bi-planar method widely applied in the fluoroscopy-based navigation is investigated through theoretical analysis and computer simulation. The error distribution characteristics under the influence of the factors such as the distance between the fiducials and the number of the fiducials are obtained. The results indicate that increasing the number and spacing of the fiducials can reduce the positioning error. The configuration of the 5-point quadrangle yields a smaller error than the configurations of 4-point rectangles and 4-points triangles. This research provides a reference for the fiducials configuration selection to improve the registration accuracy in the CAOS.
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