Breast screening with microwave pulses

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OBJECTIVES: This Discovery Grant program proposes development of a low-power pulsed microwave device for breast tissue screening, including design, implementation and testing on patient volunteers. The device will complement existing clinical measurements rather than replace them; the proposed system is intended for regular screening as a tool for monitoring changes and significant departures from a healthy baseline. SCIENTIFIC APPROACH: The primary goal of the program is to develop and test a prototype of a bra-like detection device that incorporates a networked array of microwave sensors which can be used regularly by women at home or in small family clinics. Recent research suggests that low-power microwaves can detect small, early-stage tumors by exploiting the electrical contrast between malign tumors and healthy breast tissue in the microwave frequency range (100MHz – 10GHz). If a tumor is present, then part of an incident electromagnetic wave, launched into the tissue, scatters. The microwave propagation loss in the fatty tissue of the breast is sufficiently low to allow for this scatter to be detectable by receiving antennas on the skin surface. The antenna elements are inexpensive and small, so they can be woven into the fabric of a bra, a structure that is familiar, comfortable and simple to use. Acquired signals will be processed with sophisticated algorithms, yielding results that can alert the physician to potential abnormalities. METHODOLOGY: Several clearly identified components of the proposed prototype will be examined concurrently. 1. Antenna design and layout. The antenna-sensors need to be small, inexpensive and printed on a flexible substrate. In addition to targeting favorable characteristics of individual antennas, the number of sensors, as well as their relative layout will be optimized within spatial and hardware constraints. The substrate and the medium which couples the breast to the antennas need to be chosen in accordance with average electrical properties of the breast tissue. These challenges will be addressed through thorough simulation, fabrication and testing. 2. Microwave pulse generation. The signals fed to the transmitting antennas will be custom-shaped for selection of the frequency range of interest, as well as optimal usage of antenna capabilities. 3. The switching mechanism. Antenna elements act as transmitters one at a time, while the rest of the network operates in the receiving mode. Each scan involves a set of sequential measurements as the antennas take turns in their transmitting and receiving roles. This task includes careful consideration of circuit connections which will minimize signal loss and maintain signal integrity. 4. Sequential anomaly detection. In collaboration with experts in the signal-processing field, sophisticated algorithms will be developed to detect any abnormalities and significant changes. Regular feedback will be collected from medical experts to assess the range of changes which correspond to normal tissue changes due to hormonal cycles. The algorithms will be tested on synthetic signals (obtained through electromagnetic simulation with comprehensive MRI-derived human breast models) as well as on signals measured with realistic breast phantoms and volunteers. 5. Overall system design for patient comfort. This includes investigations of overall patient position (standing or prone), softness of materials in contact with skin, and minimizing the scan time. CONTRIBUTION TO TRAINING HIGHLY-QUALIFIED PERSONNEL: The multi-disciplinary nature of our program allows it to be a training platform for experts in a range of areas applied to a healthcare-centered problem: electromagnetic simulation analysis, antenna design, microwave engineering and signal processing.