The Research On Microwave Thermal Therapy For Breast Cancer

Microwave Thermal Therapy and Microwave Cancer Treatment (MCT) have been widely used as a regular treatment for various types of diseases, such as liver cancer, skin cancer and so on. Compared with surgery and chemoradiotherapy, It has advantages of small side effect, high operability, good efficiency and safety. The significant difference between the dielectric parameters of tumor and health cells causes the big gap of capability of absorbing microwave energy between them. Tumor has higher water content, higher dielectric parameter and lower ability of heat dissipation, ends up with faster heating effect during the microwave treatment. And with the temperature rising up to the deadly limit for tumor effects, the bad cells will be exterminated and the health ones will be saved.This thesis focuses on the microwave thermal therapy for breast cancer, contains feasibility research, antenna designs for invasive and non-invasive treatment, human breast phantom preparation, return loss measurement of the antennas, and the experiment study of heating effect. For MCT antennas, different characteristics are being interested in compared with the traditional communication antennas. The near field characteristic is the study interest, and the SAR distribution in the near field area is the indicator of the possible treatment effect for MCT. Meanwhile the return loss of the antenna also affects the efficiency of the MCT. Thus the return loss and the near field SAR study is the emphasis of the thesis.First of all, a2.45GHz spiral microstrip antenna with sharpening for non-invasive breast cancer MCT is designed and optimized, using3D full wave simulation software HFSS, based on FEM. Ten set of SAR distributions are obtained and compared, one is selected for fabrication and experiment, whose SAR distribution is symmetrical and near field energy is concentrated on the axial of the antenna. With the modification of the structure of antenna, the return loss at2.45GHz can be optimized.Then, a2.45GHz monopole antenna with bipyramid structure and sleeve structure is designed for invasive treatment of tumors that locate deep inside the breast. By introducing topping structure, the SAR distribution on top of the antenna is enhanced, which is good for the treatment. By adding a sleeve, the back radiation is reduced, also the SAR distribution won’t change with insert depth with this sleeve. The two novel structures will affect the return loss of the antenna, the return loss will be enhanced with optimization.Moreover, the human breast phantom is prepared with adequate research of dielectric characteristics of breast for the use of following antenna tests. To verify the phantom, pig breast is used as a reference, and a good agreement is observed.Finally, the MCT experiments are conducted by using the human breast phantom. With the results acquired from temperature measurement instruments, the SAR distributions are concluded indirectly, and show good agreement with the numerical results.In this thesis, the research of MCT, from theory to application, is deeply studied, two effective MCT antennas are proposed, the human breast phantom is prepared with the reference with pig breast, and the numerical results is verified by measurement. All these novel research work build up a reference and basis for intensive study of microwave thermal therapy for breast cancer.