Magnetic fields associated with a nuclear magnetic resonance medical imaging system.
Measurements were made of magnetic and electric field levels in and around a nuclear magnetic resonance imaging system undergoing a clinical trial. Magnetic field levels ranged from 0.04 tesla (T) in the imaging volume down to about 0.0006 T at the end of the patient table. The peak radio-frequency magnetic field level was 15 amperes per meter (A/m) in the imaging volume, while the rms value was 4.6 A/m. The specific absorption rate resulting from the radio-frequency magnetic field was calculated to be no more than 0.017 watts per kilogram (W/kg). The radio-frequency electric field was detectable only within a few centimeters of the coil assembly, and does not significantly contribute to the specific absorption rate. These exposure levels were much lower than existing guidelines for clinical NMR procedures.
D002986:Clinical Trials as Topic; D004574:Electromagnetic Fields; D055590:Electromagnetic Phenomena; D004869:Equipment Safety; D006801:Humans; D009682:Magnetic Resonance Spectroscopy / Q000295:instrumentation*; D008961:Models, Structural; D012306:Risk