Neurosurgery is an ideal application for image-guided techniques, by virtue of the high precision it requires, the need to visualize nearby tissue, the need for planning of optimal trajectories to target tissue, and the need to localize visually indistinguishable, but functional different, tissue types. Early attempts to achieve image-guided neurosurgery consisted of stereotactic frames which directly provided the fiducials for registering the MRI or CT data to the patient [8]. More recently, frameless stereotaxy systems have been pursued by many groups [1,2,5,15,18,23], and usually consist of two components: registration and tracking. We have added a third, initial, component to our system - reconstructed models of the patient's anatomy. The system's components are described below.
The architecture of our image-guided surgery system (Figure 1) supports frameless, non-fiducial, registration of medical imagery by matching surface data, and supports optical tracking of patient and instrument locations. The system (Figure 1) consists of a portable cart containing a Sun UltraSPARC workstation and the hardware to drive the laser scanner and Flashpoint tracking system. On top of the cart is mounted an articulated extendable arm to which we attach a bar housing the laser scanner and Flashpoint cameras. The three linear Flashpoint cameras are inside the bar. The laser is attached to one end of the bar, and a video camera to the other. The joint between the arm and scanning bar has three degrees-of-freedom to allow easy placement of the bar in desired configurations.
