27 MHz conformal capacitive ring (CR) applicators for uniform hyperthermic/diathermic treatment of body segments with axial fields

The devices consist of a pair of ringlike, flexible capacitive electrodes, conformally wrapped round the tissue to be heated. These capacitive ring (CR) applicators produce an axial E-field which can uniformly heat the central portion of a 20-cm OD cylindrical phantom simulating fat and muscle tissues. This electrode-body configuration can be used to heat most human body segments uniformly with the highest symmetry congruence, the RF currents flowing parallel to the boundaries provided by the pseudoaxial symmetry of these segments. With respect to the rigid pads used in RF capacitive heating, the CR electrodes exhibit a larger working surface area. Moreover, they can be used with an interposed dielectric layer between the electrodes and the skin to reduce edge effects. With respect to the axially symmetric radiators of higher frequency, they are applicable to larger cross-section body segments with increased penetration and without the need of an integral water bolus. The CR devices allow free access to most of the body surface for skin temperature measurement and conditioning and for combined treatments.