A method of monitoring a radiation amount received from an X-ray source in an X-ray imaging system for taking an X-ray image of an object includes the steps of obtaining one or more depth images from one or more depth cameras； the one or more depth cameras covering at least an area covered by an X-ray bundle of an X-ray source of the X-ray imaging system； positioning the object against or on a surface including radiation measurement chambers and identifying select radiation measurement chambers underneath the object from the one or more depth images and/or from a single depth image derived from the one or more depth images； and activating the select radiation measurement chambers.
