Investigation of Histology Region in Dielectric Measurements of Heterogeneous Tissues

Abstract

The dielectric properties of tissues are key parameters in electromagnetic medical technologies. Despite the apparent simplicity of the dielectric measurement process, reported data has been inconsistent for heterogeneous tissues. Dielectric properties may be attributed to heterogeneous tissues by identifying the tissue types that contributed to the measurement through histological analysis. However, accurate interpretation of the measurements with histological analysis requires first defining an appropriate histology region to examine. Here, we investigate multiple definitions for the probe sensing depth and uniquely calculate this parameter for measurements with a realistic range of tissues. We demonstrate that different sensing depth definitions are not equivalent, and may introduce error in dielectric data. Lastly, we propose an improved definition, given by the depth to which the probe can detect changes in the tissue sample, within the measurement uncertainty. We equate this sensing depth with histology depth, thus supporting the need of having the tissue region that contributes to the dielectric data be the same as that which is analysed histologically. This study demonstrates that, for these tissues, the histology depth is both frequency and tissue dependent. Therefore, the histology depth should be selected based on the measurement scenario, otherwise inaccuracies in the data may result.

Broadband lung dielectric properties over the ablative temperature range: Experimental measurements and parametric models

“…Furthermore, the heating protocol was repeated with an additional two fiber optic temperature sensors positioned in tissue at distances 2 and 3 mm away from the dielectric measurement probe. These measurements were conducted to assess the variation in temperature within the sensing volume of the dielectric probe . Figure illustrates the experimental setup.…”

“…These measurements were conducted to assess the variation in temperature within the sensing volume of the dielectric probe. [28][29][30][31][32] Figure 2 illustrates the experimental setup.…”

In Vivo Dielectric Properties of Healthy and Benign Rat Mammary Tissues from 500 MHz to 18 GHz

“…The sensing depth of the custom made probe with 2.2 mm aperture is reported to be between 0.75 and 1.5 mm in homogeneous materials [17]. Similarly, the sensing depth of the slim form probe is reported to be between 1.05 and 1.41 mm for homogeneous materials [18]. For heterogeneous two layered high dielectric property contrast materials, the sensing depth is reported to be well below 1 mm [18].…”

Review of Microwaves Techniques for Breast Cancer Detection

“…The table is subdivided into five categories: the year of study, the author names, the operating frequency, the probe used in measurements, and the number of samples. The accuracy of the difference between the normal and tumourous tissues of each reported study is based on many factors such as the frequency range for the fitting model, tissue type and size, number of samples used for the study, sensing depth and volume, time from excision to measurement of tissues in the study, type of the fitting data model used, and the environment of testing (i.e., in vivo or ex vivo states) [19,20,[24][25][26][27]. Several studies have investigated the contrast between the dielectric properties of normal and malignant breast tissues [13,17].…”