Magnetic induced hyperthermia using thermosensitive ferromagnetic material

背景：热敏材料的磁感应加热可用于深部肿瘤的高局部热疗。居里温度是一个过渡点，在这个点上，材料内部的特定温度的发展导致其磁性的损失；因此，当达到这个温度时，电流停止，因此热量产生停止。低居里温度提高了整个肿瘤的自动温度控制性能，可以通过热敏材料的自调节特性来实现。我们开发了热敏铁磁粒子，该粒子通过涡流产生足够的热量，并且在43度温度下具有低居里点，可以实现自动温度控制。方法：将热敏铁磁颗粒（直径40 ~ 150μm，剂量500mg）置于1%琼脂中，通过感应加热系统在600A， 188kHz磁场下连续测量病灶内温度。结果：在磁场作用下，这些铁磁颗粒在居里点温度下的产热速率在5分钟内急剧上升，组织温度稳定在居里点，在整个受热体积内温度均匀性良好。结论：该微创手术具有良好的临床应用前景；2)热敏铁磁颗粒直径为40-100μm，比毛细血管和淋巴管大，颗粒残留在注射部位，可作为门诊患者重复接受治疗，无需每次治疗均经皮穿刺，如射频烧灼。上述结果表明，利用热敏铁磁颗粒在43℃时具有较低的居里点，可提供自动温度控制的磁致热疗法，在未来的临床应用中可能会有所转变。少

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