Numerical Simulation And Experimental Study Of Magnetic Fluid Hyperthermia Based On Multiphysics Coupling

As an emerging hyperthermia,magnetic fluid hyperthermia(MFH)has exhibited the advantages of low toxicity,high heating power and excellent transparency in the human torso.However,the difficulties in the accurate determination of temperature distribution and damage degree within treated tissues greatly constrained the clinical applications of MFH,and it is difficult to solve the above problems relying on clinical trials.Numerous studies focused on the numerical methods for the optimization of treatment parameters,by solving the magnetic field and temperature field separately.However,there does not exist a model that neatly incorporates the magnetic and thermal fields into a single calculation.In the present study,we aimed to solve the multiphysics coupling problem in the numerical simulation of MFH using the finite element method,and carry out relevant experiments to provide the verification basis for the numerical results.Firstly,the human abdomen was adopted as the study object and the simplified three-dimensional MFH model was established.Using complex magnetic permeability to solve the magnetic losses of nanoparticles during magnetization reversals,the multiphysics coupling of temperature field,magnetic field and diffusion field was successfully achieved.The optimal treatment time for deep tumors of different radii under different therapy conditions was obtained through the integral analysis of damaged tissue,and the preferable treatment conditions were deduced from the ingenious union of univariate and multivariate analysis.The results showed that the preferred magnetic field conditions are 3–11 kA/m and 200–500 kHz,and the preferred magnetic fluid parameters are 8–10 nm and 5%–10%.Moreover,it is greatly encouraged to adopt the combination of higher magnetic field strength and lower frequency,and the conjunction of higher particle size and volume concentration.Secondly,the therapy effect of typical magnetic field generating device was analysed employing the multiphysics coupling method.The change curves of the optimal treatment time over the ampere turns of coil were obtained,and the preferable range of ampere turns was proposed.The results showed that the applicable ampere turns range of electromagnet,solenoid and new magnetic field applicators were 450–2160 A,1300–6500 A,1440–4500 A,respectively,and the preferable range is 1500–2160 A,3000–5000 A,2160–3600 A,respectively.Finally,we carried out the vitro experiment of MFH,the impact of magnetic field conditions and magnetic fluid parameters on the temperature rise rate of magnetic fluid and tissue was investigated.Additioally,the validity of multiphysics coupling method was verified by comparing numerical and experimental results.The results showed that the relative error did not exceed 10%.Compared to the magnetic field parameters,magnetic fluid parameters and particle dose have less effect on the temperature rise rate of tissues.The steady temperature of magnetic fluid exhibits a non-monotonic change with increasing particle concentration,and it reached the maximum at the volume concentration of 3%.As the tissue diameter and height increased by 1 cm,the steady temperature of the magnetic fluid was reduced by 6–7 °C.