Design of magnetic circuit for radiofrequency hyperthermia

Abstract

Magnetic hyperthermia (MHT) is of considerable practical interest as a new less invasive local tumor treatment. MHT requires a uniform alternating magnetic field (AMF) over a wide volume. However, it is very difficult to actually generate the exchange magnetic field of completely uniform amplitude over a wide area such as a human body. We used electromagnetic-field simulator, Maxwell 3D, to design AMF generator. Before designing AMF generator, reliability of simulation was checked. We measured temperature changes of a magnetic fluid (Resovist®) in an AMF to determine the tolerance range of the magnetic field amplitude suitable for MHT. Then, we designed an AMF generator, optimizing the magnetic circuit parameters such as the diameter of the ferrite core, the coil current and the capacitor voltage using the simulator.