Abstract
We investigated a treatment method for hyperthermia in which a ferromagnetic implant with a low curie temperature (FILCT) is implanted into a malignant tumor and then a high-frequency magnetic field is applied outside the body. In earlier studies, we confirmed that the target temperature of the tumor can be non-invasively monitored by detecting changes in the magnetic field caused by magnetic permeability changes. It was very difficult, however, to detect FILCT temperature if the applied magnetic field was in an unstable state. Additionally, if the initial bias is higher, it becomes more difficult to detect FILCT temperature because the resolution of the lock-in amplifier is reduced. To improve the accuracy of low-invasive temperature measurement, we formulated a method that reduces the drift in the pickup coil voltage caused by instability from the applied magnetic field. In addition, we experimentally confirmed that the influence from fluctuation in the applied magnetic field can be reduced by adjusting the initial bias value near 0 V.
