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Elise C. Fear

Bio: Elise C. Fear is an academic researcher from University of Calgary. The author has contributed to research in topics: Microwave imaging & Radar imaging. The author has an hindex of 33, co-authored 168 publications receiving 5719 citations. Previous affiliations of Elise C. Fear include University of Victoria & Victoria University, Australia.


Papers
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Journal ArticleDOI
TL;DR: 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 with image formation algorithms developed to enhance tumor responses and reduce early- and late-time clutter are demonstrated.
Abstract: 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.

884 citations

Journal ArticleDOI
TL;DR: In this paper, the main focus is on active microwave systems, in particular microwave tomography and confocal microwave imaging, and the main features of active, passive, and hybrid systems under investigation for breast cancer detection.
Abstract: 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.

625 citations

Journal ArticleDOI
TL;DR: Microwave imaging for medical applications has been of interest for many years and monitoring hyperthermia is one application that has been proposed, which is the application of heat to tissue to indicate the successful deposition of heat in the tissue of interest.
Abstract: Microwave imaging for medical applications has been of interest for many years. Microwave images are maps of the electrical property distributions in the body. The electrical properties of various tissues may be related to their physiological state. For example, the properties of tissues change with temperature. One application of microwave imaging that has been proposed is monitoring hyperthermia, which is the application of heat to tissue. In this case, the changing electrical properties indicate the successful deposition of heat in the tissue of interest. Other changes in electrical properties may be caused by disease. There is some evidence of changes in the properties of cancerous tissues when compared to normal tissues. Cancer detection with microwave imaging is based on this contrast in electrical properties. Microwave imaging for breast cancer detection has also interested many researchers.

371 citations

Journal ArticleDOI
TL;DR: In this paper, a balanced antipodal Vivaldi antenna is designed to be used as a sensor for a microwave breast cancer detection system, which has the ability to send short electromagnetic pulses into the near-field, with low distortion, low loss and in a directional manner.
Abstract: 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.

365 citations

Journal ArticleDOI
TL;DR: A microwave system for breast tumor detection that uses previously introduced confocal microwave imaging techniques is presented in this paper, and the effectiveness of these skin subtraction algorithms is demonstrated.
Abstract: 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.

333 citations


Cited by
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Journal ArticleDOI
TL;DR: A large-scale study to experimentally determine the ultrawideband microwave dielectric properties of a variety of normal, malignant and benign breast tissues, measured from 0.5 to 20 GHz using a precision open-ended coaxial probe shows that the contrast in the microwave-frequency dielectrics properties betweenmalignant and normal adipose-dominated tissues in the breast is considerable, as large as 10:1.
Abstract: The development of microwave breast cancer detection and treatment techniques has been driven by reports of substantial contrast in the dielectric properties of malignant and normal breast tissues. However, definitive knowledge of the dielectric properties of normal and diseased breast tissues at microwave frequencies has been limited by gaps and discrepancies across previously published studies. To address these issues, we conducted a large-scale study to experimentally determine the ultrawideband microwave dielectric properties of a variety of normal, malignant and benign breast tissues, measured from 0.5 to 20 GHz using a precision open-ended coaxial probe. Previously, we reported the dielectric properties of normal breast tissue samples obtained from reduction surgeries. Here, we report the dielectric properties of normal (adipose, glandular and fibroconnective), malignant (invasive and non-invasive ductal and lobular carcinomas) and benign (fibroadenomas and cysts) breast tissue samples obtained from cancer surgeries. We fit a one-pole Cole-Cole model to the complex permittivity data set of each characterized sample. Our analyses show that the contrast in the microwave-frequency dielectric properties between malignant and normal adipose-dominated tissues in the breast is considerable, as large as 10:1, while the contrast in the microwave-frequency dielectric properties between malignant and normal glandular/fibroconnective tissues in the breast is no more than about 10%.

1,164 citations

Book
01 Jan 2012
TL;DR: The Modern Antenna Handbook as mentioned in this paper provides a comprehensive treatment of classical and modern antennas and their related technologies, including metamaterials, microelectromechanical systems (MEMS), frequency selective surfaces (FSS), radar cross sections (RCS), and advanced numerical and computational methods targeted primarily for the analysis and design of antennas.
Abstract: Find the most up-to-date and comprehensive treatment of classical and modern antennas and their related technologies in Modern Antenna Handbook. Have access to current theories and practices in the field of antennas, with topics like metamaterials, microelectromechanical systems (MEMS), frequency selective surfaces (FSS), radar cross sections (RCS), and advanced numerical and computational methods targeted primarily for the analysis and design of antennas. Written by leading international experts, this book will help you understand recent developments in antenna-related technology and the future direction of this fast-paced field.

911 citations

Journal ArticleDOI
TL;DR: 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 with image formation algorithms developed to enhance tumor responses and reduce early- and late-time clutter are demonstrated.
Abstract: 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.

884 citations

Journal ArticleDOI
TL;DR: This clinical experience appears to be the first report of active near-field microwave imaging of the breast and is certainly the first attempt to exploit model-based image reconstructions from in vivo breast data in order to convert the measured microwave signals into spatial maps of electrical permittivity and conductivity.
Abstract: Despite its recognized value in detecting and characterizing breast disease, X-ray mammography has important limitations that motivate the quest for alternatives to augment the diagnostic tools that are currently available to the radiologist. The rationale for pursuing electromagnetic methods is strong given the data in the literature, which show that the electromagnetic properties of breast malignancy are significantly different than normal in the high megahertz to low gigahertz spectral range, microwave illumination can effectively penetrate the breast at these frequencies, and the breast is a small readily accessible tissue volume, making it an ideal site for deploying advanced near-field imaging concepts that exploit model-based image reconstruction methodology. In this paper a clinical prototype of a microwave imaging system, which actively illuminates the breast with a 16-element transceiving monopole antenna array in the 300-1000 MHz range, is reported. Microwave exams have been delivered to five women through a water-coupled interface to the pendant breast with the participant positioned prone on an examination table. This configuration has been found to be a practical, comfortable approach to microwave breast imaging. Sessions lasted 10-15 min per breast and included full tomographic data acquisition at seven different array heights beginning at the chest wall and moving anteriorly toward the nipple for seven different frequencies at each array position. This clinical experience appears to be the first report of active near-field microwave imaging of the breast and is certainly the first attempt to exploit model-based image reconstructions from in vivo breast data in order to convert the measured microwave signals into spatial maps of electrical permittivity and conductivity. While clearly preliminary, the results are encouraging and have supplied some interesting findings. Specifically, it appears that the average relative permittivity of the breast as a whole correlates with radiologic breast density categorization and may be considerably higher than previously published values, which have been based on ex vivo tissue specimens.

765 citations

Journal ArticleDOI
TL;DR: The MIST approach is shown to offer significant improvement in performance over previous UWB microwave breast cancer detection techniques based on simpler focusing schemes.
Abstract: A method of microwave imaging via space-time (MIST) beamforming is proposed for detecting early-stage breast cancer. An array of antennas is located near the surface of the breast and an ultrawideband (UWB) signal is transmitted sequentially from each antenna. The received backscattered signals are passed through a space-time beamformer that is designed to image backscattered signal energy as a function of location. The beamformer spatially focuses the backscattered signals to discriminate against clutter and noise while compensating for frequency-dependent propagation effects. As a consequence of the significant dielectric-properties contrast between normal and malignant tissue, localized regions of large backscatter energy levels in the image correspond to malignant tumors. A data-adaptive algorithm for removing artifacts in the received signals due to backscatter from the skin-breast interface is also presented. The effectiveness of these algorithms is demonstrated using a variety of numerical breast phantoms based on anatomically realistic MRI-derived FDTD models of the breast. Very small (2 mm) malignant tumors embedded within the complex fibroglandular structure of the breast are easily detected above the background clutter. The MIST approach is shown to offer significant improvement in performance over previous UWB microwave breast cancer detection techniques based on simpler focusing schemes.

710 citations