Theoretical temperature distributions for solenoidal-type hyperthermia systems

One type of system proposed for producing hyperthermia for cancer therapy of deep-seated tumors consists of a cylindrical conducting coil (solenoid) in which the patient (or a limb of the patient) is placed. The current in the conducting coil creates an alternating magnetic field inside the patient, which induces eddy currents in the tissue. The eddy currents deposit power and hence produce heating. In this paper, steady-state temperature profiles are calculated analytically, assuming a homogeneous one-dimensional model which includes blood perfusion. Numerical methods are used to calculate the temperature distributions as a function of time for this homogeneous model and to calculate the temperature profiles when there are radial variations in tissue parameters including blood flow. Based on these computer simulations, it would appear that in most cases a solenoid-type hyperthermia system will not be able to provide deep-seated heating in the abdomen or thorax, but should be able to raise temperatures to therapeutic levels to about 6 cm depth in the abdomen and in the muscle layer in the thorax.