Aberrant Heating: A Problem in Regional Hyperthermia

A 180 cell block model of man has been used to compute the pattern of energy deposition when radio-frequency applicators are used for treatment of cancer by hyperthermia. When the abdomen is exposed with polarization parallel to the length of the body at frequencies from 10 to 60 MHz, approximately 60-70 percent of the total energy is deposited outside of the abdomen. This fraction is increased to as much as 90 percent at several resonances which occur between 100 and 500 MHz. The local rates of energy deposition in the arms, neck, chest, and thighs often exceed that in the abdomen. The pattern of this aberrant heating is dependent upon the positions of the arms and legs. Aberrant heating appears to be much less pronounced for treatment of the thigh or upper arm than it is for treatment of the abdomen.