Magnetic resonance imaging apparatus and apparatus for measuring radio frequency output for the same

An apparatus for measuring radio frequency output for a magnetic resonance imaging apparatus, comprising:

• a directional coupler variable in degree of coupling, and configured to attenuate a radio frequency signal which is generated in a radio frequency signal generator and amplified in a radio frequency power amplifier;
• a signal controller configured to control the degree of coupling of the directional coupler;
• and
• a converter configured to perform a digital conversion of the radio frequency signal from the directional coupler so as to output a digital signal.

A magnetic resonance imaging apparatus, comprising:

• a static magnetic field magnet configured to generate a static magnetic field;
• a gradient coil configured to generate a gradient magnetic field where intensity of a magnetic field varies,
• a transmission coil which is a radio frequency coil configured to generate a radio frequency magnetic field;
• a radio frequency power amplifier configured to amplify a radio frequency signal generated in a radio frequency signal generator and to provide the amplified radio frequency signal to the transmission coil;
• a plurality of directional couplers different in degree of coupling from each other, and configured to attenuate the radio frequency signal amplified in the radio frequency power amplifier;
• a comparator configured to compare input-level information of the signal inputted into the radio frequency power amplifier with a threshold value;
• a switcher configured to switch to any one of the plurality of the directional couplers based on a result of the comparison so as to output a radio frequency signal by the one directional coupler;
• a converter configured to perform a digital conversion of the radio frequency signal from the one directional coupler so as to output a digital signal;
• and
• a calculator configured to calculate a specific absorbed fraction based on the radio frequency signal outputted from the converter.