Elise C. Fear

Confocal microwave imaging for breast cancer detection: localization of tumors in three dimensions

The physical basis for breast tumor detection with microwave imaging is the contrast in dielectric properties of normal and malignant breast tissues. Confocal microwave imaging involves illuminating the breast with an ultra-wideband pulse from a number of antenna locations, then synthetically focusing reflections from the breast. The detection of malignant tumors is achieved by the coherent addition of returns from these strongly scattering objects. In this paper, we demonstrate the feasibility of detecting and localizing small (<1 cm) tumors in three dimensions with numerical models of two system configurations involving synthetic cylindrical and planar antenna arrays. Image formation algorithms are developed to enhance tumor responses and reduce early- and late-time clutter. The early-time clutter consists of the incident pulse and reflections from the skin, while the late-time clutter is primarily due to the heterogeneity of breast tissue. Successful detection of 6-mm-diameter spherical tumors is achieved with both planar and cylindrical systems, and similar performance measures are obtained. The influences of the synthetic array size and position relative to the tumor are also explored.

Enhancing breast tumor detection with near-field imaging

This article outlines the main features of active, passive, and hybrid systems under investigation for breast cancer detection. Our main focus is on active microwave systems, in particular microwave tomography and confocal microwave imaging.

Microwave detection of breast cancer

Breast cancer affects many women, and early detection aids in fast and effective treatment. Mammography, which is currently the most popular method of breast screening, has some limitations, and microwave imaging offers an attractive alternative. A microwave system for breast tumor detection that uses previously introduced confocal microwave imaging techniques is presented in this paper. The breast is illuminated with an ultrawide-band pulse and a synthetic scan of the focal point is used to detect tumors; however, the geometric configuration and algorithms are different from those previously used. The feasibility of using small antennas for tumor detection is investigated. Signal processing algorithms developed to mitigate the dominant reflection from the skin are described, and the effectiveness of these skin subtraction algorithms is demonstrated. Images of homogeneous and heterogeneous breast models are reconstructed with various numbers of antennas. Both the influence of antenna spacing and the suitability of simplified models for system evaluation are examined.

Tissue Sensing Adaptive Radar for Breast Cancer Detection&#8212;Experimental Investigation of Simple Tumor Models

Microwave breast cancer detection is based on differences in electrical properties between healthy and malignant tissues. Tissue sensing adaptive radar (TSAR) has been proposed as a method of microwave breast imaging for early tumor detection. TSAR senses all tissues in the volume of interest and adapts accordingly. Simulation results have shown the feasibility of this system for detecting tumors of 4 mm in diameter. In this paper, the second-generation experimental system for TSAR is presented. Materials with electrical properties similar to those in the breast are used for the breast model. A resistively loaded Wu–King monopole antenna is fabricated, and reflections from the breast model over the frequency range of 1–10 GHz are recorded. The reflected signals are processed with the TSAR algorithm, which includes improved skin subtraction and TSAR focusing algorithms. Various tumor models are examined; specifically, a 1-cm tumor is detected with a signal-to-clutter ratio of 10.41 dB. Tumor detection with the experimental system is evaluated and compared to simulation results.

Balanced Antipodal Vivaldi Antenna With Dielectric Director for Near-Field Microwave Imaging

A balanced antipodal Vivaldi antenna is designed to be used as a sensor for a microwave breast cancer detection system. The antenna has the ability to send short electromagnetic pulses into the near-field, with low distortion, low loss and in a directional manner. The antenna directivity is further improved by the inclusion of a novel feature in the antenna aperture called a “director” which consists of a profiled piece of higher dielectric constant material. Several simulated results are successfully confirmed with measurements. Reflections of a tumor placed in a breast model are simulated for two cases, namely a balanced antipodal Vivaldi antenna with and without a director. Greater tumor responses are recorded with the director present, demonstrating the potential of this feature for microwave breast imaging.

Experimental feasibility study of confocal microwave imaging for breast tumor detection

Initial experimental verification of confocal microwave imaging for breast tumor detection is described. Simple phantoms, consisting of a PVC pipe and objects representing tumors, are scanned with resistively loaded monopole or horn antennas. Successful reduction of clutter and detection of a variety of two-dimensional objects is demonstrated.

Microwave Breast Imaging With a Monostatic Radar-Based System: A Study of Application to Patients

A prototype microwave breast imaging system is used to scan a small group of patients. The prototype implements a monostatic radar-based approach to microwave imaging and utilizes ultra-wideband signals. Eight patients were successfully scanned, and several of the resulting images show responses consistent with the clinical patient histories. These encouraging results motivate further studies of microwave imaging for breast health assessment.

Microwave imaging of the breast.

Microwave imaging for medical applications has been of interest for many years. Recently, microwave imaging for breast cancer detection has gained attention due to advances in imaging algorithms, microwave hardware and computational power. The breast is relatively translucent to microwaves, accessible for imaging, and there appears to be a significant electromagnetic property contrast between tumors and healthy tissues. Therefore, breast imaging may be the first clinically viable application of microwave imaging. This paper reviews recent developments in passive, hybrid, and active approaches to microwave breast cancer detection.

A prototype system for measuring microwave frequency reflections from the breast

Microwave imaging of the breast is of interest for monitoring breast health, and approaches to active microwave imaging include tomography and radar-based methods. While the literature contains a growing body of work related to microwave breast imaging, there are only a few prototype systems that have been used to collect data from humans. In this paper, a prototype system for monostatic radar-based imaging that has been used in an initial study measuring reflections from volunteers is discussed. The performance of the system is explored by examining the mechanical positioning of sensor, as well as microwave measurement sensitivity. To gain insight into the measurement of reflected signals, simulations and measurements of a simple phantom are compared and discussed in relation to system sensitivity. Finally, a successful scan of a volunteer is described.

Compact antenna for Radar-based breast cancer detection

Microwave imaging for breast cancer detection is based on the contrast in electrical properties of healthy fatty breast tissues and malignant tumors. This inherent contrast causes microwave reflections from tumors embedded in normal tissues. Radar-based breast imaging detects tumors by observing variations in microwave signals reflected from the tumors as the antenna location changes. The topics of this paper are the development of a compact antenna for the detection of cross-polarized reflections and the application of this antenna to radar-based breast cancer detection. The antenna is designed, simulated, constructed and measured. The capabilities and limitations of the antenna for detecting tumor models are investigated through simulation and experiments, demonstrating the potential of this method for the detection of tumors in the breast.