Brodeur P, Dansereau J, De Guise J, Labelle H
Institute de Génie Biomédical, Ecole Polytechnique, Montréal, Québec, Canada.
Ann Chir. 1997;51(8):861-7.
A computer assisted surgery system has been developed to quantify the vertebral displacements induced by the Cotrel-Dubousset instrumentation and to visualize in 3-D the spine at different per-operative steps. This spinal surgery is realized to correct idiopathic scoliosis. Per-operative measurements are obtained by using a magnetic digitizer. Five points per thoracic vertebra and six points per lumbar vertebra are digitized. The method proposed estimates the location of the digitized points on a computer graphics 3-D model of vertebrae by a point-to-surface matching algorithm. The 3-D models are constructed before the surgery using multiplanar radiographic reconstruction technique (2 or 3 views) and geometric modeling methods. Computer tools permit the 3-D visualization of the spine peroperatively and the evaluation of clinical indices such as Cobb angles and vertebral rotations. The system includes 3 principal error sources: 2) reconstruction error; 2) digitizer error (digitizer precision) and 3) point-to-surface matching error. In order to validate the overall system, measurements have been simulated for 2 vertebrae and 2 digitizers of different precision, taking onto account the reconstruction error. For 5 and 6 digitized points per vertebra, the matching algorithm gives a RMS error of respectively 3.0 and 2.0 mm.
已经开发出一种计算机辅助手术系统，用于量化Cotrel-Dubousset器械引起的椎体位移，并在三维空间中可视化脊柱在不同手术步骤中的情况。这种脊柱手术旨在矫正特发性脊柱侧凸。术中测量通过使用磁性数字化仪获得。每个胸椎数字化5个点，每个腰椎数字化6个点。所提出的方法通过点到面匹配算法估计数字化点在计算机图形学椎体三维模型上的位置。三维模型在手术前使用多平面放射成像重建技术（2或3个视图）和几何建模方法构建。计算机工具允许术中对脊柱进行三维可视化，并评估诸如Cobb角和椎体旋转等临床指标。该系统包括3个主要误差源：1）重建误差；2）数字化仪误差（数字化仪精度）和3）点到面匹配误差。为了验证整个系统，考虑到重建误差，对2个椎体和2个不同精度的数字化仪进行了测量模拟。对于每个椎体5个和6个数字化点，匹配算法的均方根误差分别为3.0毫米和2.0毫米。
