FDTD analysis of a pulsed microwave confocal system for breast cancer detection

A novel focused active microwave system is investigated for detecting breast cancer. In contrast to x-ray and ultrasound modalities, the method reviewed here exploits the breast-tissue physical properties unique to the microwave spectrum, namely, the translucent nature of normal breast tissues and the high dielectric contrast between malignant and normal breast tissues. The system uses a confocal technique and time-gating to enhance the detection of malignant tumors while suppressing the effects of tissue heterogeneity and absorption. Using published data for the dielectric properties of normal and malignant breast tissues, we have conducted a preliminary 2-D finite-difference time-domain (FDTD) computational electromagnetics analysis of the system. We considered two types of inhomogeneities of normal tissue: a statistically random variation of the dielectric parameters throughout the breast in a ±10% range, and a spatially coherent inhomogeneity representing a vein. The modeled excitation was a pulsed 6-GHz waveform. The FDTD simulations showed that malignant tumors as small as 2 mm in diameter could be robustly detected in the presence of the background clutter generated by the heterogeneity of the surrounding normal tissue. Spatial resolution of the tumor location was found to be in the order of 1 cm.