Microwave Imaging for Breast Cancer Detection

Abstract

Breast cancer is the most common form of cancer found in women. Early detection and timely medical treatment are key factors affecting long-term survival of breast-cancer patients. XRay Mammography is currently the main method of screening for breast cancer. However exposure to ionizing radiation and high percentage of false negative and false positive diagnosis, expedite the need to develop a complementary or alternative screening method. This thesis proposes using Microwave Imaging as a viable alternative to X-ray mammography. Microwave imaging system is essentially a “breast tissue radar”. It involves the propagation of very low levels (1000 times less than a mobile phone) of microwave energy through the breast tissue to measure electrical properties. The reason for using microwave is the difference between the electrical properties of normal and malignant tissues in this frequency range. Normal breast tissue is largely transparent to microwave radiation while malignant tissues which contain more water and blood will scatter microwave back toward their source. The antenna array picks up these scattered signals, which can be analysed using a computer to construct a three dimensional image showing the malignant tissues’ location and size. An experimental study into a breast cancer detection technique employing a microwave imaging system is conducted. The system uses a step-frequency synthesized pulse technique and a planar or cylindrical near-field scanning sub-system to detect the presence of small objects inside a breast phantom. A simple breast phantom in the form of a cylindrical plastic container including liquid imitating fatty tissues and small highly reflecting objects approximately emulating tumours is used in the experimental set up. A special calibration technique for the Vector Network Analyser combined with a novel signal processing approach utilising frequency-domain data is employed to enhance detection of the target. Successful detection of the target is demonstrated. The work performed as part of this Ph.D. thesis has been published in 4 journal papers and 15 conference papers, all subjected to peer-reviewing. This acceptance rate supports the claim of the originality and significance of the research undertaken as part of the thesis project