Study On Microwave Thermoacoustic/Ultrasonic Dual-mode Imaging For Breast Cancer Detection

Breast cancer is one of the most frequent malignant tumors in women.According to relevant data,breast cancer has become the most lethal cancers among women in China.Because the absorption of electromagnetic energy by breast cancer cell tissue is 2-5 times higher than that of normal breast tissue,this feature makes microwave-induced thermoacoustic tomography(MITAT)a huge advantage in the clinical detection of breast cancer.MITAT is a new type of low-cost non-invasive imaging technology based on thermoacoustic effect.It has high contrast of microwave imaging and high spatial resolution of ultrasound imaging,and has the potential of imaging deep lesions.And ultrasound imaging technology is highly sensitive to lymph nodes and is not affected by the density of breast glands.So dual-modality imaging combined with microwave thermoacoustic imaging can provide more comprehensive structural and functional information.In order to improve the sensitivity and specificity of breast cancer detection,this article combines these two imaging technologies to build a microwave thermoacoustic / ultrasound dual-modality system to load high-contrast thermoacoustic imaging information on the precise structural imaging of ultrasound,to achieve the fusion of structural and functional imaging.The main work of this article include:1.The image reconstruction part has been optimized.By integrating the acquisition program and the imaging program into the Labview panel,the time required for signal acquisition to image reconstruction is reduced,and the imaging speed is increased.The image reconstruction time is reduced from 3.6s to 0.8 s,to achieve the integration of acquisition and imaging..2.Simulating the requirements of breast cancer clinical detection,phantom experiments were carried out to optimize the microwave thermoacoustic / ultrasound dual-modality imaging system.First,the imaging performance of the microwave thermoacoustic imaging mode based on the traditional horn antenna and the handheld dipole antenna is compared.By comparison with the horn antenna,the imaging quality of the handheld dipole antenna is verified,and it is light and portable.Because it is suitable for clinical testing,the dipole antenna is used as the antenna used in the construction of the dual-mode system.3.In the case of transformer oil coupling,we conducted three sets of experiments in order to test the spatial resolution of the dual-modal system.And the experimental results show that the spatial resolution of the dual-modal system is about 0.973 mm,which is much smaller than the size of early breast cancer tumors.It validates the potential for systematic early breast cancer detection.4.A breast cancer tumor experiment was designed.The ultrasound images and thermoacoustic images of breast phantoms,breast cancer phantoms and Plexiglas rods were used to verify that the system can provide images with accurate structure and high contrast.Then we showed the image fusion results of the two groups of experiments.The registered fusion image combines the advantages of ultrasound imaging and microwave thermoacoustic imaging to make up for each other's shortcomings,which shows that our system has the ability of dual-modal imaging.5.The effects of different polarization directions and different incident angles of the dipole antenna relative to the breast phantom on imaging quality were simulated and experimentally explored.The experimental results show that the best image quality is obtained when the polarization direction angle is 90 degrees.When the incident angle is 90 degrees,the electric field distribution in the imaging plane is uniform.The results of these studies can also provide guidance for the operation of breast cancer clinical detection.These experiments and data analysis of the results verify that this microwave thermoacoustic/ultrasonic dual-modal system constructed in this paper not only has dual-modal imaging capabilities,but also can achieve structural and functional imaging fusion.And it has great potential in clinical early breast cancer screening.