In a method for examining a body region executing a periodic motion in an examination subject with a diagnostic apparatus having a radiation source for generating radiation penetrating the examination subject and a detector system for the radiation emanating from the radiation source, the intensity of the radiation emanating from the radiation source is modulated between a reference value and a reduced value compared to the reference value, substantially synchronously with the movement, so that the reference value is present during a phase of the periodic motion to be imaged with the diagnostic apparatus, and substantially only the data that were output by the detector system during the presence of the reference value of the radiation are utilized for the determination of the image.