Preparation of fine ferrite powder for local thermal coagulation technique under alternating magnetic field

点击翻译按钮获取中文摘要

Selection of ferrite powder and suitable frequency were carried out to realize a thermal coagulation technique in which tumors are locally heated to 60-80℃ by an application of alternating magnetic field from external coils after they are stuffed with ferrite powder. Various ferrite powders were heated by an alternating magnetic field in 80kHz-399kHz. In this frequency range, the largest increase in temperature (ΔT) was obtained for the MgFe_2O_4 in all the samples examined. The ΔT value was almost proportional to the applied power and the weight of the powder. The heating ability for the Mg-ferrite was ca. 86 J・min^<-1>・g^<-1> under AC magnetic field (200 W, 370 kHz). The heating ability in alternating magnetic field was clearly depended on the magnitude of the hysteresis loss for the ferrite powder. Fine Mg_<1-x>Ca_xFe_2O_4 ferrite powders for local thermal coagulation therapy were synthesized by a reverse coprecipitation method. The enhancement of temperature under an AC magnetic field was improved by the partial Ca^<2+> substitution. A high heat ability was obtained for the samples calcined at 300℃ and 800℃.