An X-ray imager has a navigation-aid subsystem including one or more transmitters (TX), one or more receivers (RX) and one or more reflectors (RFL). A radio signal is transmitted by transmitter (TX), is then reflected off reflector RFL and is then received at receiver (RX). The received signal is then resolved into positional correction information that can be used to guide a motion of the imager's tube (S) and or detector (D) to position and/or align the tube (S) and/or detector (D) relative to each other in a desired spatial configuration to ensure optimal imaging results. The imager may be a mobile imaging system with the detector (D) portable.