【作者】 李康；

【导师】 张秀敏；

【作者基本信息】 北京交通大学 ， 电气工程， 2017， 硕士

【摘要】 磁流体热疗是肿瘤热疗的一个分支,因为具有无毒副作用、靶向性等特点,与其他热疗方法相比具有明显优势,逐渐成为国内外肿瘤治疗的研究热点。目前磁流体热疗的研究主要集中在材料制备和实验方面,缺乏有效的理论支撑。本文从磁流体在交变磁场中的发热原理出发,对热疗过程中人体组织的升温情况进行了研究分析,为磁流体热疗的实际应用提供理论依据。首先,对超顺磁性的磁流体纳米颗粒在交变磁场中的发热原理进行了研究,并根据尼尔弛豫和布朗弛豫两种磁损耗机制推导出磁流体的发热功率。通过改变磁流体和交变磁场参数对发热功率进行了对比分析,结果表明发热功率受磁场频率、磁场强度、颗粒直径、体积分数等因素的影响。其次,对人体组织中的热传递方式进行了分析,根据Pennes生物传热方程建立了人体组织的传热数学模型。在二维空间下用有限元法对组织的温度分布进行了计算,并应用COMSOL软件模拟仿真出组织在热疗过程中的温度分布情况。对组织温度分布的影响因素进行了对比分析,提出多点注射的方法,能够显著提高热疗效果。然后,根据磁路理论设计出交变磁场发生装置,仿真结果证实了磁场分布较为均匀,可用于磁流体热疗。创新性地建立了磁场与温度场的耦合模型,通过耦合仿真分析研究了磁场频率、磁场强度、人体组织参数、血液灌注率对磁流体热疗效果的影响,得到最佳的参数条件。最后,利用设计的磁流体热疗实验装置进行了试管实验和离体组织实验。试管实验结果表明了磁流体发热受到磁场频率和磁场强度的影响,与理论分析相吻合。通过离体组织实验得到组织的升温规律,与仿真分析基本符合,证实了仿真的有效性和实验的可行性。更多还原

【Abstract】 Magnetic fluid hyperthermia(MFH)is a type of the hyperthermia used in the treatment of tumors.Compared with other hyperthermia methods,MFH has obvious advantages,namely its targeted nature and absence of toxicity or side effects.Thus it has become a popular research topic in the field of tumor treatment in China and abroad.At present,the studies of MFH tend to focus on material preparation and experiments,but lack effective theoretical support.Guided by the principle that magnetic fluids produce heat in the alternating magnetic field,this dissertation conducts relevant studies on temperature rise in human tissues during the process of hyperthermia,to provide a theoretical basis for the application of MFH.First,research into the principle of superparamagnetic magnetic fluid nanoparticles producing heat in the alternating magnetic field is carried out,and the heating power of magnetic fluids is deduced according to Neel and Brownian relaxation magnetic loss mechanisms.Comparative analysis on heating power is made among different cases by changing the parameters of magnetic fluids and alternating magnetic fields.Analysis of results shows that the heating power is affected by a variety of factors,including magnetic field frequency,magnetic field intensity,particle diameter,and volume fraction.Second,after analysis on the heat transfer modes in human tissues,the mathematical model of heat transfer model in human tissues is established on the basis of the Pennes bioheat transfer equation.The temperature distribution of tissues is calculated in a two-dimensional space through the finite element method,and the tissues’ temperature distribution during the process of hyperthermia is simulated through the COMSOL software.The influencing factors of tissues’ temperature distribution are compared and analyzed,in order to support that the multi-point injection method can significantly improve the effect of hyperthermia.Next,the alternating magnetic field generating device is designed according to the magnetic circuit theory.The simulation results confirm that the magnetic field distribution is even and can be used for MFH.The coupled model of the magnetic field and temperature field is established,and it is used to analyze the effects of magnetic field frequency,magnetic field intensity,human tissue parameters and blood perfusion rate on MFH,in order to ensure the optimal parameters are obtained.Finally,the designed MFH experimental device is used to conduct test tube and in vitro tissue experiments.The results of test tube experiments show that the heat production of magnetic fluids is affected by magnetic field frequency and intensity,which is consistent with the theoretical analysis.The rules of temperature rise in tissues are obtained through the in vitro tissue experiments,which conform to the simulation analysis,confirming the validity of simulation and the feasibility of experiments.更多还原