Three-dimensional SAR distributions computed in a multilayered cylindrical model for electromagnetic hyperthermia

A model consisting of multilayered, concentric, circular cylinders is used to investigate numerically specific absorption rate (SAR) distributions for electromagnetic hyperthermia. The fields in the cylinders are expanded in eigenfunctions, and axial confinement is achieved via Fourier transformation. Only axisymmetric SAR distributions are considered. TM₀ modes have SAR distributions that appear to be most useful for hyperthermia of deep-seated tumors. As the SAR is more confined axially: (1) the radial components of the TM₀ mode fields increase, and (2) the attenuation in the radial direction increases. Differences in SAR distributions are more apparent near the surface of a model than they are near the core. The effect of axial confinement on the optimal frequency of operation is discussed