Power absorption in ferromagnetic implants from radiofrequency magnetic fields and the problem of optimization
Power absorption in ferromagnetic implants from radiofrequency magnetic fields and the problem of optimization
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DOI：
10.1109/22.97482
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发表时间：
1991-11
影响因子：
4.3
通讯作者：
S. Haider;T. Cetas;James R. Wait;J. S. Chen
中科院分区：
文献类型：
--
作者：
S. Haider;T. Cetas;James R. Wait;J. S. Chen
对于间质性热疗中使用的植入物，获得了小铁磁圆柱体中因诱导涡流循环而产生的射频磁场（使用准静态近似）吸收功率的显式表达式。据发现，最佳的功率吸收每单位体积的圆柱形植入物发生时，所施加的磁场是平行的圆柱体的轴和感应数（即两倍的植入物半径的比，皮肤深度）是2.5。这一结果被用来设计植入物的几何配置，以实现最佳的加热效果。计算了圆柱形植入物相对于磁场极化的取向上的吸收功率的依赖性，发现与实验结果吻合良好。>
Explicit expressions for absorbed power in small ferromagnetic cylinders from a radiofrequency magnetic field (using a quasi-static approximation) due to induced eddy current circulation are obtained for implants used in interstitial hyperthermic therapy. It is found that optimum power absorption per unit volume of cylindrical implant occurs when the applied magnetic field is parallel to the axis of the cylinder and the induction number (i.e. two times the ratio of implant radius to skin depth) is 2.5. This result is used to design geometrical configurations for implants to achieve optimum heating effects. The dependence of absorbed power on the orientation of the cylindrical implant with respect to polarization of the magnetic field is calculated and found to be in good agreement with experimental results. >