Development of a Family of RF Helical Coil Applicators Which Produce Transversely Uniform Axially Distributed Heating in Cylindrical Fat-Muscle Phantoms

Uniform transverse heating, without excessive surface heating, in phantoms which simulate human limbs or trunks has long been sought after as a precursor for predictable hyperthermia treatment of deep-seated cancerous tissues. A family of helical coils developed at the National Center for Devices and Radiological Health has induced transversely uniform axially distributed heating in the muscle portion of simulated fat-muscle, cylindrical arm- and thigh-sized phantoms without excessively heating the simulated fat. The final design parameters for the coils were derived using different sized coil/phantom combinations and electric (E)-and magnetic (H)-field strength measurement scans. Transverse heating patterns, in the form of thermographic pictures, will be the principal format for presentation of the experimental data in this paper. Independent nonperturbing thermometry data are also included to enhance the accuracy of the thermographic results obtained.