ABSTRACT
I. Introduction .............................................................................................................................55 II. RF Magnetic Fields and MR Procedures ...............................................................................56 III. MR Safety Standards ..............................................................................................................56 IV. Magnetic and Electric Fields: SAR Calculations...................................................................57 V. Theoretical Estimation of Whole-Body SAR.........................................................................58 VI. RF Energy-Induced Hot Spots................................................................................................59 VII. SAR in Birdcage Coils and Conductors near Patients...........................................................65 VIII. Experimental Measurements of Whole-Body SAR ...............................................................66 IX. Local SAR from Transmit/Receive RF Surface Coils ...........................................................66 X. Experimental Determination of Local SAR ...........................................................................67 XI. Safety Considerations for Receive-Only RF Surface Coils ...................................................68 XII. Possible Mechanisms for RF Bioeffects ................................................................................68 XIII. Thermal Physics and Physiology Literature ..........................................................................68 XIV. Summary and Conclusions .....................................................................................................69 References ........................................................................................................................................70
Radiofrequency (RF) energy is defined as non-ionizing electromagnetic radiation in the frequency range of 0 to 3000 GHz, as distinguished from the very high photon energies and frequencies associated with ionizing electromagnetic radiation (e.g., gamma and X-rays). The RF spectrum includes radar, ultra high frequency (UHF) and very high frequency (VHF) television, AM and FM radio, and microwave communication frequencies. Resonant RF magnetic fields are used in magnetic resonance (MR) for imaging and spectroscopy procedures.
