In a method for controlling a radio-frequency device, and a magnetic resonance tomography system and a radio-frequency control device wherein the method is implemented, the RF device of a magnetic resonance tomography system is emitted during a magnetic resonance measurement of an examination subject that is moving relative to the transmission field of the RF device. The RF device emits RF pulses at chronological intervals, and measurement values are measured at chronological intervals. At chronological intervals, position values are determined that represent a current position of the examination subject relative to the transmission field. On the basis of the measurement values and the position values, exposure values are determined that represent a physiological degree of effectiveness that the RF pulses have on the subject exposed to the RF pulses. Based on a multiplicity of exposure values, exposure control values are respectively formed. The RF device is limited in its functioning if an exposure control value reaches or exceeds an exposure limit value.