Increased radio-frequency power absorption in human tissue due to coupling between body coil and surface coil tech./dosim.

By: Boesiger P, Buchli R, Saner M, Meier D
Published in: Ann N Y Acad Sci 1992; 649: 160-165
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Exposure

Exposure Parameters
Exposure 1: 64 MHz
Modulation type: pulsed
Exposure duration: 15 min

Exposure 1

Main characteristics
Frequency 64 MHz
Type
Exposure duration 15 min
Modulation
Modulation type pulsed
Duty cycle 2.6 %
Additional info

repetition time 500 ms echo time (6 echos): 50-300 ms
Exposure setup
Exposure source
  • 1.5 T whole body imager
Setup coil placed concentrically on the face of the phantom (2 cm high, r = 6 cm) in such a way that coil center and phantom center coincide
Parameters
Measurand Value Method Remarks
magnetic flux density 11.7 µT measured from the transmitting radio-frequency
magnetic flux density 12 µT calculated without surface coil
magnetic flux density 14 µT measured without surface coil
magnetic flux density 112 µT calculated with surface coil with mechanical tuning capacitors
magnetic flux density 94 µT measured with surface coil with mechanical tuning capacitors
magnetic flux density 6 µT measured with surface coil with variocaps
SAR 0.3 W/kg calculated from transmitting B-field
SAR 24 W/kg calculated from induced B-field