Considerations of radiofrequency induction heating for localised hyperthermia

A finite difference technique for studying both spatial and temporal variations in temperature in tissues subjected to local hyperthermia is described. The calculation offers speed and simplicity whilst remaining stable. Its form is discussed in both 3-dimensional Cartesian coordinates and cylindrical coordinates. The technique is used to predict RF induction heating of a plane skin-fat-muscle model. Physical and physiological parameters are incorporated. These include the contributions to heating from both E and H fields associated with a plane coil, heat transfer across the skin surface for various environmental conditions, and an appropriate dependence of blood flow on temperature for each tissue layer. The effects on tissue temperature of varying each of a number of parameters in the model are considered.