The analysis of affecting factors on the application accuracy of interactive image guided surgery

In this study the authors studied different factors that might affecting the application accuracy of interactive image guided neurosurgery. A phantom was mounted with the standard ring and also implanted with a frameless marker system that randomly distributed markers on the surface of the phantom. The target point was digitized and the coordinates were recorded and compared with reference points. The tip of each semi-invasive fiducial marker was digitized to achieve a frameless transformation matrix, and the special points on the Zamorano-Dujovy ring were digitized to achieve a frame-based transformation matrix. The differences from the reference points were used as the deviation from the "true point". The mean square root was calculated to show the sum of vectors. Different image quality and marker distribution were compared. A paired t-test was used to analyze results. The results of the phantom showed that the mean square roots were 2.57/spl plusmn/0.54 mm and 1.53/spl plusmn/0.68 mm respectively (p<0.001). These preliminary results showed that the implantable semi-invasive fiducial can provide more accurate localization for many procedures. The motion of the ring after computed tomographic scan was the main reason for the errors in the frame-based system.