Patent ID: 7622921

Claim:
A method for monitoring a physiologically effective radio-frequency exposure in a defined volume of an examination subject in a magnetic resonance data acquisition sequence in a magnetic resonance system, said magnetic resonance system comprising a radio-frequency antenna structure having a plurality of individually controllable radio-frequency signal channels that collectively generate a radio-frequency field distribution in an examination volume in which the examination subject is disposed during said sequence, each of said radio-frequency channels having a radio-frequency signal associated therewith selected from the group consisting of a radio-frequency signal emitted by that radio-frequency channel in said sequence and a radio-frequency signal to be emitted by that radio-frequency signal channel in said sequence, said method comprising the steps of: for each of said radio-frequency signal channels, detecting an amplitude value and a phase value of the radio-frequency signal associated therewith at a plurality of known acquisition points in time; for each of said known acquisition points in time for each of said radio-frequency signal channels, automatically electronically determining respective local exposure values from the respective amplitude and phase values, the local exposure values respectively representing a physiological exposure caused by the radio-frequency signal at a known location in the examination volume; for each of said radio-frequency signal channels, automatically electronically forming exposure control values from the local exposure values; comparing the respective exposure control values with respective predetermined exposure limit values; and generating a control signal that alters at least one of said radio-frequency signals if an exposure limit value is met or exceeded.