| Traditional cancer treatment methods are characterized by strong invasiveness and severe side effects,which seriously affect the quality of life of patients.In recent years,the results of some cell and clinical experiments have shown that low-intensity(1 V/cm-3 V/cm)and medium-frequency(100 kHz-300 kHz)alternating electric field can specifically inhibit the proliferation of malignant cells without harming normal cells.This kind of field is called tumor treating fields(TTFields).Although TTFields has been verified to have good effects in the treatment of various cancers,its physical mechanism still lacks a reasonable and systematic explanation.Therefore,this thesis studies the electric field distribution under different conditions from the three levels of single cell level,multicellular level and organ level through finite element method(FEM),and analyzes the key factors affecting the effect of electric field in tumor treatment.This thesis firstly constructs single cell models of different shapes,sizes and division stages.By calculating the distribution of the electric field inside and outside the cell and the change of the transmembrane voltage under alternating electric fields at different frequencies,it is shown that the intermediate frequency electric field has a selective effect on dividing cells.Then,the influence of the presence of organelles and membrane pores on the electric field distribution is considered,and on this basis,the values of the electric field stress on the cell membrane,the electric field force and the dielectrophoretic force are calculated.The results show that only the dielectrophoretic force can interfere with the mitosis of cells,and the ways are to affect the movement of larger particles in the cell during division,change the material exchange efficiency near the pores of the cell membrane,and change the shape of the cytoskeleton.Based on the single cell model,a multicellular model with different cell spacings is established in this thesis.The narrowing of the intercellular distance does not significantly attenuate the intracellular field strength,but instead increases the inhomogeneity of the intracellular electric field,making it more effective on malignant cells that are more crowded and often in division.In order to further increase the authenticity of the multicellular model,cell boundary segmentation is performed based on the pathological microscopic images of breast cancer to obtain multi-cellular models of benign tissue and malignant tissue,and the difference in the internal electric field between the two is analyzed.Aiming at the problem that it is difficult to obtain the distribution of the electric field in the human body through actual measurement during the treatment process,this thesis divides the breast into four parts: skin,mammary gland,fat and muscle based on CT images,and completes the three-dimensional reconstruction of the breast.The electric field distribution of the mammary gland is calculated,and the results show that the electric field in this area can reach the intensity required for treatment.By adding a virtual tumor in the breast,it is found that the average field strength inside the tumor has little relationship with the tumor radius,but has a negative correlation with the conductivity of the tumor. |
