Three-dimensional FDTD analysis of a pulsed microwave confocal system for breast cancer detection: design of an antenna-array element

Abstract

We are investigating a new ultrawide-band (UWB) microwave radar technology to detect and image early-stage malignant breast tumors that are often invisible to X rays. In this paper, we present the methodology and initial results of three-dimensional (3-D) finite-difference time-domain (FDTD) simulations. The discussion concentrates on the design of a single resistively loaded bowtie antenna element of a proposed confocal sensor array. We present the reflection, radiation, and scattering properties of the electromagnetic pulse radiated by the antenna element within a homogeneous, layered half-space model of the human breast and the polarization and frequencyresponse characteristics of generic tumor shapes. We conclude that the dynamic range of a sensor array comprised of such elements in conjunction with existing microwave equipment is adequate to detect small cancerous tumors usually missed by X-ray mammography. Index Terms-Antenna array, cancer, FDTD methods. I. INTRODUCTION A potentially important strategy for reducing breast cancer mortality is the detection of early-stage tumors [1]. X-ray mammography is currently the most effective screening modality for detecting clinically occult breast cancers. However, approximately 10-30% of breast cancers are missed by mammography [2], [3]. The significant number of false negatives may be attributed to the limitations of mammography in: 1) assessing dense glandular tissue and regions located close to the chest wall or underarm and 2) imaging very early-stage tumors that do not yet exhibit microcalcifications. Another concern is the high rate of false positives in screening mammograms [3], [4]. These statistics indicate a critical need for complementary modalities with high sensitivity and specificity for early detection through low-cost screening. Ultrasound and contrast-enhanced MRI are effective in the diagnostic evaluation of mammographically detected breast lesions. However,

Numerical Modelling for Ultra Wideband Radar Breast Cancer Detection and Classification

“…It should be noted that although lymph nodes are not constituents of the breast per se, they are represented in this figure as breast cancer can be diagnosed through detection of metastasised tumour cells particularly in the axillary lymph nodes, where approximately 50% of breast cancer occur [18,19]. …”

Thermal Therapy, Part IV: Electromagnetic and Thermal Dosimetry

“…Microwave imaging has been explored as a new modality for breast cancer diagnosis since tissue physical properties are unique to the microwave spectrum, namely, the translucent nature of normal breast tissues and the signifi cant contrast in the dielectric properties of normal tissue and malignant tumors. 238,239 Although the specifi c contrasts vary with frequency and among the results from different groups, there is now a general belief that these contrasts are substantial, especially near 800 MHz. [240][241][242][243][244] Other clinical evaluations were made with radiometers for measuring changes in lung water, 222 cerebral temperatures, 223 measurement of blood fl ow, 225 and infl ammatory arthritis.…”

An Overview of Uwb Antennas for Microwave Imaging Systems for Cancer Detection Purposes

“…In that sense, some techniques based on microwave signals using image reconstruction algorithms have been investigated [8][9][10][11]. Compared to X-rays, microwave imaging can be safely repeated more frequently because it is free from ionizing radiation [12].…”