Breast Cancer Detection Via CPML Boundary And UWB Antenna Design

Ultra-wideband(UWB) imaging is currently a new technique used in breastcancer screening. Comparing with other detection system, UWB technique doesn’temploy ionizing radiation and uncomfortable compression of the breast, it has becomeone of the more promising breast cancer detection method and attracted the interest ofmany research groups all over the world.The perfectly matched layer(PML) absorbing boundary condition is a commonmethod to truncate the Finite Difference Time Domain(FDTD) lattices. Among manykinds of PML, Stretched Coordinate PML(SC-PML) is easy to achieve as a breastmodel absorbing boundary, and a new Convolutional PML(CPML) was modifiedfrom this SC-PML. Comparing with traditional PML, CPML performs bettercharacters in dispersive, nonlinear, anisotropic medium. In breast cancer detection,breast model was built by media with above properties and a CPML absorbingboundary was adopted to truncate this breast model. Detailed test of CPML reflectiveinformation was implemented by applying an sine signal in the center of the model,the reflectivity of CPML is easy to get with FDTD method. Time-consuming wascompared by the same computer with CPML layers of4,6,8. Images of breast modeltruncated by different layers were given by confocal and beamforming algorithm.Experiment shows CPML is an effective absorbing boundary.A3D breast model was built by FDTD method with MATLAB software. Thismodel take dispersive factor into consideration and better approximate to humanbreast. FDTD method can simulate UWB microwave propagation in breast model, itemploys many kinds of antenna array in detection simulation to transmit and receivesignals. Each antenna has different bandwidth, shape, and imaging performance.Confocal imaging and beamforming imaging were used to form the inner breaststructure. Finally, An antenna whose bandwidth ranges from4GHz to7.5GHz leads tobetter imaging quality.