A reference device (166) for surgery includes a substrate (156) forming a matrix of windows (154) configured to be attached to an external portion of a body. The windows provide access location choices from which access to a target area may be determined. A radiopaque marker (150) is integrated with the substrate such that the at least one radiopaque marker is visible in X-ray images. A fixing mechanism (155) is coupled to the substrate to secure the substrate in contact with the body to prevent motion of the substrate relative to the body. Methods and systems using this device are also disclosed.