Abstract
Summary
It is apparent that errors in the measurement of temperature, due to the presence of a metallic needle (thermocouple, without leads) in tissue during exposure of that tissue to a high frequency electric field are greater when the time of exposure is short and when the intensity of the electric field is low. The relationship of the heat produced in deep-lying tissues to the heat produced in superficial tissues is dependent on the distance at which the condenser plates are placed with respect to the locations of the tissues. This fact is of importance in the therapeutic uses of high frequency fields (radiotherms). When a considerable air space separates these plates from the surface of the tissue, the change in temperature produced in the deep-lying intra-articular tissue is greater than that produced in the subcutaneous tissue. The converse relationship maintains when the plates are placed close to the surface of the tissue. This dielectric layer effect is superimposed or any specific heating due to difference in constitution of tissue and variation in wave length of radiation which may be present. Schliephake 1 , 2 first demonstrated this type of depth effect of the high frequency field, and has presented experimental evidence which indicates that high frequency treatment plates which are allowed to make contact with the surface of tissue produce a tissue heating which is closely comparable with that of diathermy, in which the production of heat is predominantly in the superficial layers of tissue.
The experimental evidence presented clearly demonstrates that it is possible to produce abnormally high temperature in a chosen region (i. e., knee joint of a dog) by means of local applications of short wave electric energy of sufficient intensity.
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