Research On Magneto-thermal Coupling Mechanism Of Magnetic Fluid Hyperthermia

Magnetic fluid hyperthermia is one of the safe and efficient physical technology that can treat tumors.Magnetic fluid hyperthermia can selectively destroy malignant cells by controlling the heating temperature due to the malignant cells sensitive to heat than normal cells.The magnetic fluid hyperthermia has the advantages of high safety,precise targeted therapy,high heating efficiency,and strong universality.Therefore,magnetic fluid hyperthermia has great potential in the field of tumor therapy and can improve the quality of life of patients.The therapeutic effect of Magnetic fluid hyperthermia is controlled by the temperature distribution in the tissue.In this paper,a magnetic fluid hyperthermia model was established to analyze the influence of different factors on the distribution of effective therapeutic volume and temperature field,so as to provide theoretical guidance for clinical application.(1)The characteristics of magnetic nanoparticles were studied.Acccording to the heating principle of magnetic materials in an alternating magnetic field,the numerical relationship between the effective relaxation time,Neel relaxation time and Brownian relaxation time was studied when the nanoparticles radius ranged from 5nm to 10 nm.The results show that the effective relaxation time was determined by the smaller values of the two kinds of relaxation time.The heating power of magnetic nanoparticles in alternating magnetic field is deduced,and the influence of the diameter of magnetic fluid particles,magnetic anisotropy constant,magnetic field frequency,magnetic field intensity and other factors on the heating power of magnetic fluid is analyzed.(2)Combining the heating power of magnetic nanoparticles,the MHD flow in tissue model,the magnetic liquid diffusion model and the heat transfer model of biological tissue are established.The temperature distribution in the tissue during magnetic fluid hyperthermia is simulated by the COMSOL Multiphysics software.The factors on the effective treatment volume and the temperature distribution such asthe diffusion time of magnetic liquid,infusion rate and injection volume,volume concentration,blood perfusion rate were analyzed.(3)The influence of the number of injection points and injection location on the temperature field was analyzed when multi-point injection was adopted,and it was found that multi-point injection could significantly improve the hyperthermia effect.The magnetic fluid hyperthermia model with blood vessels was established,and it was found that the blood vessels would have a cooling effect on the temperature field,and the presence of blood vessels would affect the distribution of magnetic nanoparticles,resulting in a slightly higher central point temperature than that without the blood vessel model.(4)The simulation results of helmholtz coil show that the magnetic field distribution is uniform and can be used for magnetic fluid hyperthermia.The coupling model of magnetic field and temperature field was established,and the effects of magnetic field frequency,magnetic field intensity and human tissue parameters on magnetic fluid hyperthermia were studied by coupling simulation.