Microwave detection of breast tumors using the finite difference time domain method

With the development of modern computer technologies and techniques, a computational approach to accurately and analytically solving complicated electromagnetic problems becomes possible. Various numerical methods were developed to predict the characteristics of the electromagnetic fields in complicated structures. The Finite Difference Time Domain (FDTD) algorithm, introduced by K. S. Yee in 1996, is one of the most popular tools. FDTD begins with the general Maxwell's curl equations in time domain; it applies to a large number of linear and nonlinear materials and various geometries. Numerous technologies are used to make the FDTD calculation more efficient and accurate, among these are conformal calculation, non uniform mesh and anisotropic perfect matched layers (APMLs) boundary conditions.; It is well known that early detection of tumors is key in reducing cancer mortality. Although X-ray mammography is currently the most popular technology in breast cancer screening, about 10--30% of early cases are missed by the mammogram. It has been found that breast tumors' electrical properties at microwave frequencies are significantly different from those of healthy breast tissues; thus, microwave technology is particularly promising for breast cancer detection. Over the past several years, steady progress has been made towards realizing this dream. In this research, 2 dimensional and 3 dimensional conformal non-uniform FDTD Maxwell's solvers are developed to simulate the breast cancer early detection system. We apply a virtual-focus scanning method to detect a tumor inside a simplified breast model in which breast tissue, ribs, tumor and antennas are simulated to resemble a real case. The tumor can be located very accurately. We believe that a simple method such as the one we propose in this research is needed in order to make a detection system reliable and practical.; In addition, conformal calculations and APMLs boundary conditions are applied in the codes which will make the solution more accurate. Conformal calculations use the weighted electromagnetic parameters of the media in the boundary between two objects in the computation domain. APML shows better absorbing results than other absorbing boundary conditions.; This research shows that using FDTD to simulate microwave breast tumor detection system is an efficient way to solve the complex electromagnetic problems. Combined with the tumor's high reflections in the microwave band, we get a high signal to noise level. We conclude that FDTD simulation will improve the real detection system which can detect breast cancer in the early stages.