The RF toroidal transformer as a heat delivery system for regional hyperthermia

A novel working principle for a RF (radio-frequency) hyperthermia applicator, suitable for heating large cylindrical volumes of coaxial loads, is described. The system includes a toroidal inductor as an active device producing an almost uniform electric field, which is polarized along the toroidal z axis in the space inside the toroidal ring where the conductive tissue is placed. This electric field produces axial RF currents which, in turn, produce the required heating, provided that a closed loop is formed by electrically connecting the conductive load through capacitive ring (CR) electrodes to form an electric circuit closed externally to the toroidal inductor. This system behaves like a toroidal transformer (TT), the secondary circuit of which includes the dissipative load between the CR electrodes.