Patent ID: 8442616
Filing Date: 2013-05-14
Classification: G01R

Abstract:
1. A radio-frequency transmitter device for a magnetic resonance apparatus, comprising: a transmitter antenna system comprising a plurality of transmitter channels; and a monitoring device that monitors transmission by said transmitter antenna system during acquisition of magnetic resonance data, said monitoring device comprising a processor configured to operate said magnetic resonance apparatus and said transmitter antenna system prior to introducing an examination subject into the magnetic resonance apparatus, to determine a reference scattering parameter matrix of the transmitter antenna system in an unloaded state, and to operate said transmission antenna system and said magnetic resonance apparatus, and, after introduction of an examination subject into the magnetic resonance apparatus, to execute a procedure, in which said transmitter antenna system participates, to acquire magnetic resonance data from the examination subject, and to determine a subject-specific scattering parameter matrix of the transmitter antenna system in a state loaded by the examination subject, and to automatically determine time-dependent transmitter amplitude vectors for each of said transmitter channels that represent radio-frequency voltage amplitudes in the respective transmitter channels, and to use said subject-specific scattering parameter matrix and said reference scattering parameter matrix and said transmitter amplitude vectors to determine radio-frequency power values that are absorbed by the examination subject at respective transmit times in said procedure, and to form a plurality of monitoring values based on the determined radio-frequency power values, and to limit operation of said radio-frequency transmitter device during the acquisition of said magnetic resonance data when one of said monitoring values equals or exceeds a predetermined boundary monitoring value, wherein the scattering parameter matrix is obtained by comparing wave magnitude vectors of outgoing waves and returning waves of said transmission antenna system, and wherein the wave magnitude vectors of outgoing waves and returning waves are obtained from outgoing and returning voltages of the transmission antenna system.