Sensing volume of open-ended coaxial probes for dielectric characterization of breast tissue at microwave frequencies
Sensing volume of open-ended coaxial probes for dielectric characterization of breast tissue at microwave frequencies
复制标题
DOI：
10.1109/tmtt.2003.809626
复制
发表时间：
2003-04-01
影响因子：
4.3
通讯作者：
Okoniewski, M
中科院分区：
文献类型：
--
作者：
Hagl, DA;Popovic, D;Okoniewski, M
我们正在使用开放式同轴探头，以确定新鲜切除的正常和患病的乳腺组织标本的介电特性。这些样本的尺寸和组成存在相当大的差异，因此需要确定最小手术样本尺寸，以便对给定的探针直径进行准确测量。我们调查了2.2和3.58毫米直径的无法兰同轴探头的低和高含水量的组织使用标准的液体，表现出类似于乳腺组织的介电特性的微波频率范围从1到20 GHz的感应体积。我们还提出了一种创新的图形技术的基础上使用的科尔-科尔图，以确定在反射系数的幅度和相位的误差阈值，它绑定在测量的复介电常数的误差到一个可接受的水平。自洽实验和时域有限差分模拟的结果表明，厚度为3.0 mm，横向尺寸为1.1 cm的组织标本是使用3.58 mm直径探头进行准确测量的最小尺寸。对于直径为2.2 mm的探头，试样的厚度和宽度应分别至少为1.5 mm和5 mm。这些结论不仅与乳腺组织表征相关，而且更普遍地与各种低水含量和高水含量生物组织的介电表征相关。
We are using open-ended coaxial probes to determine the dielectric properties of freshly excised normal and diseased breast tissue specimens. The considerable variability in size and composition of these specimens predicates the need for determining the minimum surgical specimen size that yields accurate measurements for A given probe diameter. We investigate the sensing volume of 2.2- and 3.58-mm-diameter flange-free coaxial probes for both low- and high-water-content tissue using standard liquids that exhibit dielectric properties similar to breast tissue over the microwave frequency range from 1 to 20 GHz. We also present an innovative graphical technique based on the use of Cole-Cole diagrams to determine the error thresholds in the magnitude and phase of the reflection coefficient, which bound the errors in the measured complex permittivity to an acceptable level. Results from self-consistent experiments and finite-difference time-domain simulations indicate that a tissue specimen with a thickness of 3.0 mm and a transverse dimension of 1.1 cm is the minimum size that yields Accurate measurements with the 3.58-mm-diameter probe. For the 2.2-mm-diameter probe, the specimen's thickness and width should be at least 1.5 and 5 nun, respectively. These conclusions are relevant not only to breast tissue characterization, but also more generally to the dielectric characterization of a variety of low- and high-water-content biological tissues.