Breast screening with microwave pulses

目的：本发现资助计划建议开发一种用于乳腺组织筛查的低功率脉冲微波设备，包括设计、实施和在患者志愿者身上进行测试。该设备将补充现有的临床测量，而不是取代它们；拟议的系统旨在定期筛查，作为监测变化和与健康基线的重大偏离的工具。科学方法：该项目的主要目标是开发和测试一种类似胸罩的检测设备原型，该设备包含联网的微波传感器阵列，可供女性在家中或小型家庭诊所定期使用。最近的研究表明，低功率微波可以通过利用微波频率范围(100 MHz-10 GHz)内恶性肿瘤和健康乳腺组织之间的电对比来检测小型早期肿瘤。如果存在肿瘤，则发射到组织中的入射电磁波的一部分会发生散射。乳房脂肪组织中的微波传播损失足够低，可以通过在皮肤表面接收天线来检测到这种散射。天线元件既便宜又小，所以可以编织到胸罩的面料中，这种结构熟悉、舒适、使用起来也很简单。采集的信号将用复杂的算法进行处理，产生的结果可以提醒医生潜在的异常。方法：将同时检查拟议原型的几个明确识别的组件。1.天线设计与布局。天线传感器需要体积小、价格便宜，并且印刷在柔性基板上。除了针对单个天线的有利特性外，传感器的数量以及它们的相对布局将在空间和硬件限制下进行优化。需要根据乳房组织的平均电特性来选择将乳房与天线耦合的衬底和介质。这些挑战将通过彻底的模拟、制造和测试来解决。2.微波脉冲的产生。馈送到发射天线的信号将是定制的，以选择感兴趣的频率范围以及天线功能的最佳使用。3.切换机制。天线单元一次充当一个发射机，而网络的其余部分以接收模式运行。每一次扫描都包括一组顺序测量，因为天线轮流担任发射和接收角色。这项任务包括仔细考虑电路连接，以最大限度地减少信号损失并保持信号完整性。4.序贯异常检测。与信号处理领域的专家合作，将开发复杂的算法来检测任何异常和重大变化。将定期从医学专家那里收集反馈，以评估由于荷尔蒙周期而导致的正常组织变化的范围。这些算法将在合成信号(通过使用全面的MRI得出的人类乳房模型进行电磁模拟获得)以及使用真实乳房幻影和志愿者测量的信号上进行测试。5.患者舒适度的整体系统设计。这包括检查患者的整体体位(站立或俯卧)、与皮肤接触的材料的柔软程度，以及最大限度地减少扫描时间。对培训高素质人才的贡献：我们项目的多学科性质使其成为应用于以医疗保健为中心的问题的一系列领域的专家的培训平台：电磁仿真分析、天线设计、微波工程和信号处理。

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.