ROTATING ANTENNA MICROWAVE IMAGING SYSTEM FOR BREAST CANCER DETECTION

Breast imaging using Confocal Microwave Imaging (CMI) has becoming a difficult problem, primarily due to the recently-established dielectric heterogeneity of normal breast tissue. CMI for breast cancer detection was originally developed based on several assumptions regarding the dielectric properties of normal and cancerous breast tissue. Historical studies which examined the dielectric properties of breast tissue concluded that the breast was primarily dielectrically homogeneous, and that and that the propagation, attenuation and phase characteristics of normal breast tissue allowed for the constructive addition of the Ultra Wideband (UWB) returns from dielectric scatterers within the breast. However, recent studies by Lazebnik et al. have highlighted a very significant dielectric contrast between normal adipose and fibroglandular tissue within the breast. Lazebnik also established that there was an almost negligible dielectric contrast between fibroglandular and cancerous breast tissue at microwave frequencies. This dielectric heterogeneity presents a considerably more challenging imaging scenario, where constructive addition of the UWB returns, and therefore tumor detection, is much more difficult. Therefore, more sophisticated signal acquisition and beamforming algorithms need to be developed. In this paper, a novel imaging algorithm is described, which uses a rotating antenna system to increase the number of unique propagation paths to and from the tumor to create an improved image of the breast. This approach is shown to provide improved images of more dielectrically heterogeneous breasts than the traditional fixed-antenna delay and sum beamformer from which it is derived.