The radiation applied to an object (input dose rate) during irradiation of the object by a radiation source (1) is limited during X-ray exposures. Pairs of values of a control curve which give rise to an input dose rate on the object to be examined which exceeds a predetermined maximum input dose rate are corrected by an arithmetic unit (76). This results in a corrected control curve whose entire length can be used for adjusting the desired tube parameters (tube voltage, tube current or load) without giving rise to the risk of exceeding the maximum input dose rate.