A method controls for a planned radiographic exposure the spatial position of a portable digital direct x-ray detector in a medical imaging system including multiple radiographic exposure stands. The method includes creating a three-dimensional spatial model of the medical imaging system, determining within the model the spatial position of the detector based on input received from three gravity sensors installed thereon, determining a three-dimensional volume space for each radiographic exposure stand, and checking whether the spatial position of the detector fits within the three-dimensional volume space of the radiographic exposure stand.