| Magnetic induction hyperthermia is a new method for tumor treatment developed in recent years.Because of its characteristics of heat uniformity,high targeting,and good biocompatibility,it is becoming more domestic than other tumor hyperthermia methods.A new direction for the treatment of tumors.At present,the main research of magnetic induction hyperthermia technology in China focuses on the manufacture of magnetic induction hyperthermia equipment and the preparation of magnetic medium in thermal therapy and the experiment of animal in vitro and in vivo.The coupling research on multiple physical fields in magnetic induction hyperthermia is relatively rare.Usually limited to a single biological tissue.In view of the shortcomings of the magnetic field distribution of the coil-type magnetic field generating device in small animal magnetic induction hyperthermia,the coil is optimized,and the magnetic fluid with high heat-generating efficiency is selected as the magnetic medium of magnetic induction hyperthermia.The three-dimensional rabbit model is constructed and analyzed.The distribution of electromagnetic fields and thermal fields in living organisms under different heating conditions has guiding significance for the manufacture of magnetic induction hyperthermia magnetic field generating devices and improving the clinical safety of tumor treatment.(1)The heating mechanism of the magnetic medium was analyzed.The magnetic loss of superparamagnetic nanoparticles is mainly introduced.By analyzing the magnetic loss of the magnetic medium,it is found that the superparamagnetic magnetic fluid can achieve higher heat generation efficiency because it does not require a strong applied magnetic field strength.Therefore,a superparamagnetic magnetic fluid is selected as the magnetic medium.According to the Rosensweig theory,the heating power of the superparamagnetic fluid is calculated.(2)The coupling mechanism between electromagnetic field and thermal field in magnetic induction hyperthermia is analyzed.The problem of solving electromagnetic field and thermal field is analyzed by finite element method.According to the electromagnetic field theory of the coil,the alternating magnetic field generating device is designed.The magnetic field physics field of COMSOL software is used to simulate.After the compensation coil is added at both ends of the heating coil,the uniformity of the magnetic field of the heating coil is greatly improved.According to the Pennes bioheat transfer equation,the heat transfer mathematical model of biological tissue was established.The three-dimensional rabbit model was constructed by AutoCAD2011 three-dimensional design software,and the dielectric parameters and thermophysical parameters of the organism at 100 kHz were calculated.Through the analysis of coupled field,the indirect coupling method was chosen to study magnetic induction hyperthermia.(3)The simulation results and the parameters affecting the heating effect were analyzed.When the magnetic particle has a particle size of 15 nm,the magnetic field strength is 5000 A/m,the magnetic field frequency is 100 kHz,and 41.5 ° C is used as the magnetic induction thermotherapy critical temperature,the thermal field distribution in the target position is uniform,and the tumor can be killed.purpose.The alternating magnetic field frequency,magnetic field strength and magnetic fluid material parameters were changed and simulated.It was found that the particle size of the magnetic fluid had a great influence on the heating effect.When the particle size was 16 nm,the maximum temperature reached 60.4°C.According to the distribution results of electromagnetic field and thermal field,and changing the relevant parameters,the thermal field distribution during magnetic induction hyperthermia can be estimated,which has guiding significance for actual tumor hyperthermia. |
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