A mathematical model for an intra-operative stereovision system

A mathematical model was created to predict the location and orientation of vertebrae relative to artificial markers. Because the stereovision system detects the position and orientation of artificial markers, the model was d eveloped to transform the marker motion into vertebra motion. Geometry, vec tor analysis, and stereo-radiographs were used to relate the artificial mar kers to the vertebrae. Experiments were done using stereo-radiographs and a n electromagnetic digitizer to determine the orientation and position of ve rtebrae in a simulated operating room (OR) environment. Results demonstrate d that the mathematical model performed as expected when supplied accurate data from an electromagnetic digitizer. Systematic errors in stereo-radiogr aphs however resulted in 3D reconstruction inaccuracies of 6-7mm.