Magnetic induced hyperthermia using thermosensitive ferromagnetic material

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Background : Magnetic induction heating of thermosensitive material can be used to produce highly localized hyperthermia in deep-seated tumors. The Curie temperature is a transition point at which the development of a particular temperature within the material results in loss of its magnetic properties ; as such, when this temperature is reached, there is cessation of current, and thus heat production stops. Low Curie temperature improves the performance of automatic temperature control throughout the tumor can be achieved by the self-regulating character of thermosensitive materials. We have developed the thermosensitive ferromagnetic particles, which was designed to produce enough heat by eddy current and also to have low Curie point at 43 degrees temperature to provide automatic temperature control.Method : Thermosensitive ferromagnetic particles (diameter : 40-150μm, dose : 500mg) were placed into the 1%-agar and intra-lesional temperatures were measured continuously using ceramics … More thermometer during exposure to magnetic field (600A, 188kHz) by induction heating system.Results : When exposed to magnetic field, these ferromagnetic particles show a sharp rise in the rate of heat production at temperatures at the Curie point in 5 minutes, and the tissue temperature stabilized at the Curie point with good temperature homogeneity throughout the volume heated.Conclusion : This minimally invasive method is attractive for ; 1)constant automatic temperature control in tumor was provided by low Curie point without measuring temperature, 2)the diameter of thermosensitive ferromagnetic particle is 40-100μm, which is larger than capillary blood vessel and lymphatic vessel, particles remain into the injected site, so this method make it possible to be received treatment as outpatients repeatedly without percutaneous puncture every treatment, like RF cauterization. Those results showed that the magnetic induced hyperthermia using thermosensitive ferromagnetic particle, which have low Curie point at 43 degrees temperature to provide automatic temperature control, might be made shift for clinical use in future. Less