Radiographic imaging system including: an x-ray transmission unit； an x-ray receiver unit； a plate made from a material opaque to x-rays and situated between the transmission unit and the receiver unit, the plate including at least four channels, each channel enabling a part of the x-rays emitted by the transmission unit to pass through the channel； and an image processing unit configured to determine the coordinates of the projected patterns and to calculate a position of the receiver unit from the coordinates of the projected patterns and from the coordinates of the channels.
