磁热耦合下不同注射方式对温度场的影响

磁流体热疗是具有生物相容性的磁性纳米流体注射到靶向肿瘤组织，通过施加交变磁场使注射区域升温达到杀死肿瘤组织目的。热疗期间的温度分布是磁热疗的关键因素，它直接影响了治疗效果。为分析不同注射方式对治疗效果的影响，本文采用有限元方法，建立磁热耦合模型，分析亥姆霍兹线圈产生磁场的均匀性，讨论了不同电流大小对磁场强度以及温度分布的影响。为了提升治疗效果，分析了不同注射方式对温度分布的影响，并以有效治疗体积这一参数较好的量化了治疗效果。结果表明：亥姆霍兹线圈作为磁场发生装置产生的磁场均匀性较高，不均匀度偏差在1%以内，通入线圈的电流每增加1A，磁场强度增加195.3 A/m；外加磁场条件相同，采用中心点注射时，组织内的温度最高为49.8℃，有效治疗体积最大为1 156.4 mm3，效果最好；调节外加磁场，使组织内最高温度保持48℃时，采用多点注射时有效治疗体积最大为1 530.7 mm3，治疗效果最好。因此，采用多点注射技术可以使治疗区域温度分布较为均匀，达到更好的治疗效果。

Influence of Different Injection Methods on Temperature Field Distribution Under Magneto-Thermal Coupling

Magnetic fluid hyperthermia is the injection of biocompatible magnetic nanofluids into targeted tumor tissue, and the injection area is heated by applying an alternating magnetic field to kill the tumor tissue. The temperature distribution during hyperthermia is a key factor in magnetic hyperthermia, which directly affects the therapeutic effect. In order to analyze the influence of different injection methods on the treatment effect, this paper used the finite element method to establish a magneto-thermal coupling model to analyze the uniformity of the magnetic field generated by the Helmholtz coil, and the effects of different currents on the magnetic field strength as well as the temperature distribution were discussed. In order to enhance the treatment effect, the effect of different injection methods on temperature distribution was analyzed and the treatment effect was better quantified in terms of effective treatment volume. The results show that the magnetic field generated by the Helmholtz coil as a magnetic field generating device is highly uniform, with the deviation of the inhomogeneity within 1%, and the magnetic field strength increases by 195.3 A/m for every 1A increase in the current passing through the coil. When the external magnetic field conditions are the same, the central point injection is used, the maximum temperature in the tissue is 49.8 °C, and the maximum effective treatment volume is 1156.4 mm3, and the effect is the best. When the applied magnetic field is adjusted so that the maximum temperature in the tissue is maintained at 48°C, the effective treatment volume is 1,530.7 mm3 at maximum when multi-point injection is used, and the treatment effect is the best. Therefore, the multi-point injection technique can make the temperature distribution more uniform and achieve better therapeutic effect.