Target and trajectory guidance for interactive surgical navigation systems

The proliferation of interactive surgical navigation systems (ISN) is evidence of their ability to provide useful information about current location and orientation at surgery. The utility of these systems would potentially expand with intuitive methods to guide the user towards a predefined target(s) along a predefined trajectory. A system of target and trajectory guidance is described comprised of three components: (1) auto-push that displays the plane perpendicular to the present trajectory that contains the preselected target and the distance from probe tip to this plane; (2) concentric circles and collinear spheres where spheres representing the target, entry point and wand tip are projected onto the 'autopush' plane as circles, thereby visually defining the rotations and translations required to reorient the wand to the predefined target and trajectory, and (3) projected trajectories where the ideal wand trajectory is projected onto two orthogonal planes, each of which contain the present wand trajectory. Together, these enhancements enable users of ISN to easily access small, deep intracranial structures along predefined surgical trajectories.