US Patent 9737370 Patient reference tool

A patient reference device is provided for use during a medical procedure. The patient reference device includes a housing having a back side and a front side, at least three tracking markers attached to the front side of the housing, the housing extending around the at least three tracking markers and beyond a horizontal plane defined by tops of the at least three tracking markers, the housing terminating at a substantially continuous edge, and a sterile cover attached to the substantially continuous edge of the housing for covering the housing and the tracking markers.