A 3-D impedance method to calculate power deposition in biological bodies subjected to time varying magnetic fields

A previously described two-dimensional impedance method (ibid., vol.31, p.644-51, 1984) for modeling the response of biological bodies exposed to time-varying electromagnetic fields has been extended to three dimensions. This method is useful at those frequencies where the quasistatic approximation is valid and calculates the fields, current densities, and power depositions in the bodies. Solutions using this method for homogeneous spheres in plane waves are presented and compared to the analytic solutions for the same configuration. Solutions for a man exposed to a uniform radio-frequency magnetic field at 30 MHz, are presented, as well as for a man exposed to either circularly or linearly polarized magnetic fields at 63 MHz, uniform within a portion of his body and linearly decreasing outside of that portion, which approximates the exposure in some nuclear-magnetic-resonance imaging devices.