Study On The Thermal Field Distribution Of Cholangiocarcinoma Model By Magnetic Hyperthermia

Cholangiocarcinoma is a malignant tumor with a high mortality rate,which has the characteristics of insensitivity to radiotherapy and chemotherapy,low resection rate,and poor prognosis.At present,there is still a lack of effective treatment methods,and it is urgent to find new treatment methods.Magnetic hyperthermia,as a new technology that has developed rapidly in recent years,has a high degree of targeting and extremely low side effects,and has been clinically applied to a variety of cancers.At this stage,there are few studies on magnetic hyperthermia for cholangiocarcinoma.In this thesis,magnetic hyperthermia is introduced into the cholangiocarcinoma model,and the method of multi-physics coupling and computer simulation is used to explore its effect on cholangiocarcinoma tissue.Provide reference for follow-up clinical trials.This thesis firstly compares and analyzes the magnetocaloric effects of different magnetic materials.According to Rosenweig's theory,the Neel relaxation and Brown relaxation loss mechanisms of magnetic nanoparticles under an alternating magnetic field are analyzed,and the heating power calculation equation of the magnetic fluid is deduced.Different from the previous use of a single ball model to simulate tumor magnetic hyperthermia,this thesis constructs a three-dimensional model of human abdomen,liver,bile duct,and tumor based on the location of cholangiocarcinoma,and adds real thermophysical and electrical parameters of biological tissues.Consider The effect of blood perfusion rate on temperature is analyzed.According to the actual needs of hyperthermia,a suitable alternating magnetic field generator is designed,and its spatial electromagnetic field distribution is calculated.MATLAB is used to numerically simulate the influence of the radius,magnetic anisotropy parameter,viscosity coefficient and other properties of magnetic nanoparticles on the heating effect of the magnetic fluid.And 14 simulations were carried out in advance to estimate the heating power required for the bile duct cancer model to reach the hyperthermia temperature.Then the actual heating power of the magnetic fluid is substituted into the Pennes biological heat transfer equation as the external heat source term,and the heating process is simulated in the finite element simulation platform COMSOL Multiphysics,and the temperature is visualized through post-processing,according to the following hyperthermia requirements: tumor tissue The treatment temperature is above 42? and the normal tissue is below the safety threshold of 43? to judge the therapeutic effect of hilar cholangiocarcinoma and intrahepatic cholangiocarcinoma.Finally,the influence of other unsafe factors during hyperthermia is analyzed.The results show that when the peak value of the alternating current of the heating coil is10 A,the frequency is 100 k Hz,and the number of turns is 380,the intensity of the magnetic field generated at the cholangiocarcinoma site is 9208 A/m,which can meet the field strength requirements of magnetic hyperthermia,and The uniformity of the magnetic field distribution in the treatment area is high,which ensures the controllability of the heating effect.During treatment,the bile duct cancer tissue heats up rapidly,and the temperature reaches the highest after about 500 s,and remains stable.The maximum temperature of hilar and intrahepatic cholangiocarcinoma are 46.5? and 45.8? respectively.It is worth noting that at this time,the edge of the cholangiocarcinoma tumor can reach above 42?,and the surrounding healthy tissues are kept below 43 ?,which can ensure the promotion While bile duct cancer cells undergo apoptosis,they have minimal side effects on surrounding healthy tissues.It was also verified that the large blood vessels around the bile duct did not take away too much heat,and the effect on hyperthermia was negligible.When a small amount of magnetic fluid overflows in the bile duct,the healthy bile duct below it will also be heated to 39?,but all are below the safety limit of 43?.During treatment under an alternating magnetic field,the eddy current heat effect in the trunk will cause the body surface temperature to rise slightly,up to 38.8?,and cold compresses and other methods can be considered during long-term hyperthermia.The results of this thesis are encouraging.The distribution of the thermal field of cholangiocarcinoma tissue meets the requirements of hyperthermia,and theoretically,a good therapeutic effect has been obtained.At the same time,it also predicts the influence of other unsafe factors that may exist during treatment,which is of great significance to the development of related clinical trials of magnetic hyperthermia for the treatment of cholangiocarcinoma in the future.