Control of the temperature rise in magnetic hyperthermia with use of an external static magnetic field
Control of the temperature rise in magnetic hyperthermia with use of an external static magnetic field
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DOI：
10.1016/j.ejmp.2012.08.005
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发表时间：
2013-11-01
影响因子：
3.4
通讯作者：
Saito, Shigeyoshi
中科院分区：
文献类型：
--
作者：
Murase, Kenya;Takata, Hiroshige;Saito, Shigeyoshi
本研究的目的是探讨利用外部静磁场（SMF）控制磁热疗（MH）温升的方法的有效性，并通过模拟实验推导出在交变磁场（AMF）和静磁场（SMF）存在下磁性纳米颗粒（MNPs）能量耗散的经验方程。我们使用麦克斯韦线圈对制作了一种允许在具有无场点（FFP）的SMF存在下进行MH的器件。我们测量了不同AMP和SMF条件下MNPs的温升以及与FFP的不同距离(d)，并从温度曲线的初始斜率计算出比吸收率（SAR）。SAR值随SMF强度的增大而减小（H-s），随SMF梯度的增大而减小（G(s)）。SAR与H-s和SAR与d之间的关系可以用Rosensweig方程很好地近似，其中AMF （H-ac）的振幅由H-ac(2)/根H-ac(2) + H-s(2)代替，但G(s)较小的情况除外。总之，使用带有FFP的外部SMF将有效地控制MH内的温度升高，以减少加热周围健康组织的风险，我们的经验方程将有助于估计AMF和SMF存在时的SAR，并为MH设计有效的局部加热系统。(C) 2012 Associazione Italiana di Fisica Medica。Elsevier Ltd.出版。版权所有。
Our purpose in this study was to investigate the usefulness of a method for controlling the temperature rise in magnetic hyperthermia (MH) using an external static magnetic field (SMF), and to derive an empirical equation for describing the energy dissipation of magnetic nanoparticles (MNPs) in the presence of both the alternating magnetic field (AMF) and SMF through phantom experiments.We made a device that allows for MH in the presence of an SMF with a field-free point (FFP) using a Maxwell coil pair. We measured the temperature rise of MNPs under various conditions of AMP and SMF and various distances from the FFP (d), and calculated the specific absorption rate (SAR) from the initial slope of the temperature curve.The SAR values decreased with increasing strength of SMF (H-s) and d. The extent of their decrease with d increased with an increase of the gradient of SMF (G(s)). The relationships between SAR and H-s and between SAR and d could be well approximated by Rosensweig's equation in which the amplitude of AMF (H-ac) is replaced by H-ac(2)/root H-ac(2) + H-s(2) except for the case when G(s) was small.In conclusion, the use of an external SMF with an FFP will be effective for controlling the temperature rise in MH in order to reduce the risk of heating surrounding healthy tissues, and our empirical equation will be useful for estimating SAR in the presence of both the AMF and SMF and for designing an effective local heating system for MH. (C) 2012 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.