US Patent 10456201 Skull-mounted instrument trajectory guide

An instrument guiding trajectory guide can include a ball-and-socket motion constrained by an arch. Z-height adjustment of a trajectory guide lumen can be provided, with or without a ball-and-socket, such as to permit target-centered alignment of the trajectory to a target. A polar-offset or x-y stage can be included. Contrast-enhanced imageable fiducial marker concentric rings can be used to help align the trajectory to the target. The concentric rings can be progressively smaller in a direction along the trajectory.