Adam Santorelli

Time-Domain Multistatic Radar System for Microwave Breast Screening

This letter presents an experimental system for microwave breast cancer detection that uses multistatic radar. The system operates by transmitting a short-duration pulse and collecting the signals scattered within the breast. We describe the 16-element array, along with the pulse generation scheme, switches, and all auxiliary equipment. This work provides a sample selection of the collected time-domain data and shows the proof of concept by imaging the breast tumors in realistically shaped breast phantoms.

Flexible 16 Antenna Array for Microwave Breast Cancer Detection

Radar-based microwave imaging has been widely studied for breast cancer detection in recent times. Sensing dielectric property differences of tissues has been studied over a wide frequency band for this application. We design single- and dual-polarization antennas for wireless ultrawideband breast cancer detection systems using an inhomogeneous multilayer model of the human breast. Antennas made from flexible materials are more easily adapted to wearable applications. Miniaturized flexible monopole and spiral antennas on a 50-μm Kapton polyimide are designed, using a high-frequency structure simulator, to be in contact with biological breast tissues. The proposed antennas are designed to operate in a frequency range of 2-4 GHz (with reflection coefficient (S11) below -10 dB). Measurements show that the flexible antennas have good impedance matching when in different positions with different curvature around the breast. Our miniaturized flexible antennas are 20 mm × 20 mm. Furthermore, two flexible conformal 4 × 4 ultrawideband antenna arrays (single and dual polarization), in a format similar to that of a bra, were developed for a radar-based breast cancer detection system. By using a reflector for the arrays, the penetration of the propagated electromagnetic waves from the antennas into the breast can be improved by factors of 3.3 and 2.6, respectively.

Experimental Demonstration of Pulse Shaping for Time-Domain Microwave Breast Imaging

We experimentally demonstrate a low-cost hardware technique for synthesizing a speciflc electromagnetic pulse shape to improve a time-domain microwave breast imaging system. A synthesized broadband re∞ector (SBR) fllter structure is used to reshape a generic impulse to create an ad-hoc pulse with a speciflcally chosen frequency spectrum that improves the detection and imaging capabilities of our experimental system. The tailored pulse shape beneflts the system by improving the level of signal detection after transmission through the breast and thus permits higher-resolution images. We report on our ability to use this technique to detect the presence of tumours in realistic breast phantoms composed of varying quantities of glandular tissue. Additionally, we provide a set of images based on this experimental data that demonstrates the increased efiectiveness of the system using the SBR-shaped pulse in the localisation and identiflcation of the embedded tumour.

Investigation of Classifiers for Tumor Detection with an Experimental Time-Domain Breast Screening System

In this work we examine, for the flrst time, the use of classiflcation algorithms for early- stage tumor detection with an experimental time-domain microwave breast screening system. The experimental system contains a 16-element antenna array, and testing is done on breast phantoms that mimic breast tissue dielectric properties. We obtain experimental data from multiple breast phantoms with two possible tumor locations. In this work, we investigate a method for detecting the tumors within the breast but without the usual complexity inherent to image-generation methods, and conflrm its feasibility on experimental data. The proposed method uses machine learning techniques, namely Support Vector Machines (SVM) and Linear Discriminant Analysis (LDA), to determine whether the current breast being scanned is tumor-free. Our results show that both SVM and LDA methods have promise as algorithms supporting early breast cancer microwave screening.

A Time-Domain Microwave System for Breast Cancer Detection Using a Flexible Circuit Board

We present the design of a flexible multilayer circuit board for use in a custom-built microwave system for breast health monitoring. The flexible circuit features both an integrated solid-state switching network and 16 wideband antennas, which transmit short-duration pulses into the breast tissues and receive the backscattered responses. By integrating the switching matrix and the antenna array on the same substrate, we reduce the overall cost and size of the system in comparison with previously demonstrated systems in the literature. We characterize the performance of the flexible circuit board using our clinically tested experimental system and demonstrate its functionality through successful imaging of dielectrically realistic breast phantoms that simulate the presence of a tumor. This represents a step toward a more patient-friendly, compact, cost-effective, and wearable design in contrast to previous systems in the literature that required a clinical table or used bulky rigid antenna housings and electromechanical switching networks.

A Wearable Microwave Antenna Array for Time-Domain Breast Tumor Screening

In this work, we present a clinical prototype with a wearable patient interface for microwave breast cancer detection. The long-term aim of the prototype is a breast health monitoring application. The system operates using multistatic time-domain pulsed radar, with 16 flexible antennas embedded into a bra. Unlike the previously reported, table-based prototype with a rigid cup-like holder, the wearable one requires no immersion medium and enables simple localization of breast surface. In comparison with the table-based prototype, the wearable one is also significantly more cost-effective and has a smaller footprint. To demonstrate the improved functionality of the wearable prototype, we here report the outcome of daily testing of the new, wearable prototype on a healthy volunteer over a 28-day period. The resulting data (both signals and reconstructed images) is compared to that obtained with our table-based prototype. We show that the use of the wearable prototype has improved the quality of collected volunteer data by every investigated measure. This work demonstrates the proof-of-concept for a wearable breast health monitoring array, which can be further optimized in the future for use with patients with various breast sizes and tissue densities.

Time-Domain Microwave Radar Applied to Breast Imaging: Measurement Reliability in a Clinical Setting

This work presents an evaluation of the measurement challenges in clinical testing of our microwave breast cancer screening system. The time-domain radar system contains a multistatic 16- antenna hemi-spherical array operating in the 2{4GHz frequency range. We investigate, for the flrst time with such a system in clinical trials, the repeatability of measurements and its efiect on image reconstruction. We record vertical and horizontal measurement uncertainties under difierent scenarios and verify using previously introduced compensation methods that they can be successfully reduced to an acceptable level from the standpoint of image reconstruction. We also examine how placement of an immersion medium can afiect collected breast scan data. Finally, we probe the repeatability and consistency of measurements with patients. With the goal of conflrming the feasibility of frequent breast health monitoring, with our system, we obtain a total of 342 breast scans collected over 57 patient visits to determine how much scan data varies when there are no changes in between scans, and how much it varies when the patient is repositioned in the system. We conflrm that, by taking care in patient positioning in the system and with respect to the immersion medium, the measurement repeatability is high.

Microwave Breast Screening in the Time-Domain: Identification and Compensation of Measurement-Induced Uncertainties

In this work we examine several sources of measurement uncertainty that can hinder the use of time-domain microwave techniques for breast imaging. The efiects that are investigated include those due to clock and trigger jitter, antenna movements, discrepancies in antenna fabrication, and random measurement noise. We explore the signiflcance of the noise contribution of each efiect, and present methods to mitigate them when possible and necessary. We demonstrate that, after applying the aforementioned methods, the noise is minimized to the noise ∞oor of the system, thereby enabling successful tumor detection.

Microwave breast cancer detection via cost-sensitive ensemble classifiers: Phantom and patient investigation

Abstract Microwave breast screening has been proposed as a complementary modality to the current standard of X-ray mammography. In this work, we design three ensemble classification structures that fuse information from multiple sensors to detect abnormalities in the breast. A principled Neyman–Pearson approach is developed to allow control of the trade-off between false positive rate and the false negative rate. We evaluate performance using data derived from measurements of heterogeneous breast phantoms. We also use data collected in a clinical trial that monitored 12 healthy patients monthly over an eight-month period. In order to assess the efficacy of the proposed algorithms we model scans of breasts with malignant lesions by artificially adding simulated tumour responses to existing scans of healthy volunteers. Tumour responses are constructed based on measured properties of breast tissues and real breast measurements, thus the simulation model takes into account the heterogeneity of the breast tissue. The algorithms we present take advantage of breast scans from other patients or tissue-mimicking breast phantoms to learn about breast content and what constitutes a “tumour-free” and “tumour-bearing” set of measurements. We demonstrate that the ensemble selection-based algorithm, which constructs an ensemble of the most informative classifiers, significantly outperforms other detection techniques for the clinical trial data set.

Flexible sixteen monopole antenna array for microwave breast cancer detection.

Radar based microwave imaging (MI) has been widely studied for breast cancer detection in recent times. Sensing dielectric property differences of tissues over a wide frequency band has been made possible by ultra-wideband (UWB) techniques. In this paper, a flexible, compact monopole antenna on a 100 μm Kapton polyimide is designed, using a high frequency structure simulator (HFSS), to be in contact with biological breast tissues over the 2-5GHz frequency range. The antenna parameters are optimized to obtain a good impedance match over the required frequency range. The designed antenna size is 18mm × 18mm. Further, a flexible conformal 4×4 ultra-wideband antenna array, in a format similar to that of a bra, was developed for a radar-based breast cancer detection system.