A registration fixture or plate is configured for use with a medical imaging system. The registration fixture may be an optical magnetic registration plate including a plurality of fiducial markers in arranged in a predefined unique pattern. The pattern can be unambiguously detected on 2D image of the plate produced by the medical imaging system. Association of the 2D imaged pattern of fiducial markers with the actual 3D pattern on the optical magnetic registration plate allows for accurate calculation of projection matrices and co-registration of the 3D and 2D coordinate systems.