Cavagnaro Marta, Ruvio Giuseppe
Department of Information Engineering, Electronics, and Telecommunications, Sapienza University, Piazzale Aldo Moro 5, 00185 Rome, Italy.
School of Medicine, National University of Ireland Galway, University Road, H91 TK33 Galway, Ireland.
Sensors (Basel). 2020 Jul 4;20(13):3756. doi: 10.3390/s20133756.
Dielectric characterization of biological tissues has become a fundamental aspect of the design of medical treatments based on electromagnetic energy delivery and their pre-treatment planning. Among several measuring techniques proposed in the literature, broadband and minimally-invasive open-ended probe measurements are best-suited for biological tissues. However, several challenges related to measurement accuracy arise when dealing with biological tissues in both ex vivo and in vivo scenarios such as very constrained set-ups in terms of limited sample size and probe positioning. By means of the Finite Integration Technique in the CST Studio Suite software, the numerical accuracy of the reconstruction of the complex permittivity of a high water-content tissue such as liver and a low water-content tissue such as fat is evaluated for different sample dimensions, different location of the probe, and considering the influence of the background environment. It is found that for high water-content tissues, the insertion depth of the probe into the sample is the most critical parameter on the accuracy of the reconstruction. Whereas when low water-content tissues are measured, the probe could be simply placed in contact with the surface of the sample but a deeper and wider sample is required to mitigate biasing effects from the background environment. The numerical analysis proves to be a valid tool to assess the suitability of a measurement set-up for a target accuracy threshold.
生物组织的介电特性已成为基于电磁能量传递的医学治疗设计及其预处理规划的一个基本方面。在文献中提出的几种测量技术中，宽带和微创开放式探头测量最适合生物组织。然而，在体外和体内场景中处理生物组织时，会出现一些与测量精度相关的挑战，例如在有限样本大小和探头定位方面设置非常受限。借助CST Studio Suite软件中的有限积分技术，针对不同的样本尺寸、探头的不同位置，并考虑背景环境的影响，评估了高含水量组织（如肝脏）和低含水量组织（如脂肪）复介电常数重建的数值精度。研究发现，对于高含水量组织，探头插入样本的深度是重建精度的最关键参数。而在测量低含水量组织时，探头可以简单地放置在与样本表面接触的位置，但需要更深更宽的样本以减轻背景环境的偏差影响。数值分析被证明是评估测量设置是否适合目标精度阈值的有效工具。
