We compare two optical tracking systems with regard to their suitability for soft tissue navigation with fiducial needles: The Polaris system with passive markers (Northern Digital Inc. (NDI); Waterloo, Ontario, Canada), and the MicronTracker 2, model H40 (Claron Technology, Inc.; Toronto, Ontario, Canada). We introduce appropriate tool designs and assess the tool tip tracking accuracy under typical clinical light conditions in a sufficiently sized measurement volume. To assess the robustness of the tracking systems, we further evaluate their sensitivity to illumination conditions as well as to the velocity and the orientation of a tracked tool. While the Polaris system showed robust tracking accuracy under all conditions, the MicronTracker 2 was highly sensitive to the examined factors. |