"Design, Calibration, and Inversion Algorithms for Novel Microwave Tomography Systems"

这一研究计划的主要研究目标是提高用于生物医学成像应用的微波断层成像(MWT)系统的性能。MWT使用微波测量来创建感兴趣对象(OI)的体电材料属性的定量图像；通常是OI的复介电常数。在生物医学应用中，OIS通常是人体的原位区域，其目标是使用构建的复介电常数图来识别该区域中的异常或病变组织，例如，对癌症组织的成像和检测。MWT用于生物医学诊断成像的独特优势是，重建的介电常数图不直接以任何其他模式成像，因此包含用于诊断的唯一和补充信息。对于生物医学应用，当前最先进的MWT系统的最大性能问题是，与CT和MRI等其他成像方式相比，空间分辨率有限。为了成为一种可行的模式，必须提高MWT的可达到的分辨率，同时保持重建的复介电常数图的准确性。为了实现这一目标，拟议中的研究将研究MWT的三个主要方面：a)用于从适当校准的散射场数据创建图像的反演算法；b)从MWT系统获取原始测量并为反演算法产生适当数据的校准技术；以及c)MWT系统本身的设置，它影响必须使用的电磁(EM)模型以及校准程序。MWT的这三个方面是相互关联的，有时甚至是微妙的，而这项研究的一个基本论点是，只有通过这三个方面的联合研究，才能大幅提高当前的MWT成像性能。

The main research goal of this proposed research program is to improve the performance of Microwave Tomography (MWT) systems for biomedical imaging applications. MWT uses microwave measurements to create a quantitative image of the bulk-electrical material properties of an object-of-interest (OI); typically the complex permittivity of the OI. In biomedical applications the OIs are typically in situ regions of the human body and the goal is to use the constructed complex permittivity maps to identify abnormal or diseased tissue in that region, e.g., the imaging and detection of cancerous tissue. The unique advantage of MWT for biomedical diagnostic imaging is that the reconstructed permittivity map is not directly imaged in any other modality and therefore contains unique and complementary information upon which to base a diagnosis. For biomedical applications, the greatest performance issue with current state-of-the-art MWT systems is the limited spatial resolution compared to other imaging modalities such as CT and MRI. In order to be a viable modality the achievable resolution of MWT must be increased while retaining the accuracy of the reconstructed complex permittivity maps. To achieve this goal the proposed research will investigation the three main aspects of MWT: a) the inversion algorithms used to create the images from appropriately calibrated scattered field data, b) the calibration techniques which take raw measurements from the MWT systems and produce appropriate data for the inversion algorithms, and c) the MWT system set-ups themselves which affect the electromagnetic (EM) model which must be used as well as the calibration procedure. These three aspects of MWT are interrelated, in sometimes subtle ways, and it is a fundamental thesis of this proposed research that a substantial enhancement of current MWT imaging performance can only be accomplished via the joint study of these three aspects.