Investigation Of Microwave Detection Scheme For Early Breast Cancer Based On FDTD Method

Breast cancer is a sarcomata disease which is harmful to the health of women. Its incidence is on the first place of all the malignant tumor of women and the mortality rate is high. Early detection is an important way to lower its mortality. Breast tumor detection technology has been a highlight of medical imaging science all over the world. At present common imaging technologies for breast cancer such as X-ray imaging and ultrasound imaging have their limitation in some case. There is distinct difference in electromagnetic properties between normal breast tissues and malignant tumor, far greater than the differences using in other imaging technologies. This difference is the physics foundation for microwave breast near-field detection. At present most of these researches is focus on the active microwave imaging, which is based on the solution of inverse scattering problem with the irradiation of microwave on the breast.This paper introduces the common method of breast cancer detection, analyzing advantage and disadvantage of them. Then the differences between normal breast tissue and malignant tissues were detailed analyzed. Under the microwave band, these differences in dielectric constant and conductivity were all above five times. This phenomenon induces the normal breast tissues is more translucent than malignant tissues in the irradiation of microwave. This is the physical basis of microwave detection for breast cancer. At microwave frequencies, breast imaging with passive, hybrid, and active methods has been explored for several decades. This paper introduces all of them and specifies the active microwave imaging method, including its algorithm, simulation and practical systems.In this paper, the finite difference time domain (FDTD) method is used for the research of microwave breast imaging method. First, we have some basic simulations using FDTD and a unsplited perfect matched layer (PML) absorb boundary condition. Then two digital breast models were established, including the simple cubic breast model and the ellipsoid model based on magnetic resonance imaging (MRI) data. We analyze the property of two models under the irradiation of microwave by simulation, which is feasibility of detecting the breast cancer.The inverse scattering problem brings the lager computation amount and time needing because in this process ill-posedness and nonlinear problems should be settled. Thus this paper presents a primary localization scheme. This scheme can be used for reducing computation time. We carve up the computation area using coarse grid. We test a possible grid as a tumor, and commutate using FDTD method, comparing the result with measurement data, and then the least difference will be funded indicating the practical tumor position. This paper proves the feasibility of this scheme, and proves the stability in several actual conditions. The result indicates that this scheme can localize the position of tumor in -10dB interfere by optimizing the antenna array.