Development of a dielectric equivalent gel for better impedance matching for human skin

Abstract

It would be useful to develop a tissue equivalent gel to improve the uniformity of the electromagnetic field in the human body, and for making a tissue equivalent dielectric human phantom. In this study, solid type, water based gelatin-honey gels were developed which have the electrical characteristics of skin tissue. It was demonstrated that a stable and homogeneous gel, with a relative dielectric constant epsilon ' chosen from desired ranges found in skin, can be made for 200-400 MHz.

Reduction of a High-field Dielectric Artifact with Homemade Gel

“…We made our pad from gelatin produced from pig skin (13.5z), honey syrup (50.1z), NaCl (1.7z) and distilled water (34.7z), utilizing a method reported previously. 7 The gelatin corresponds to solidity and relative dielectric constant, honey syrup corresponds to relative dielectric constant with antiseptic action, and NaCl shows conductivity. The gel's dielectric equivalent is adjusted to approximate that of human skin.…”

“…1,3,5 Other causal factors include interference related to shortened radiofrequency (RF) wave on a high-tesla magneticˆeld, electromagnetic wave impedance mismatching of the air-to-tissue interface at the surface of an object, and multiple current-carrying elements in RF coils. 1,[6][7][8] Shortened RF wavelengths cause various problems in the high-tesla magnetiĉ eld because changes in wavelength are inversely proportional to the strength of B0. Shortened wavelength would be partly re‰ected, partly transmitted, and partly absorbed at an object's surface.…”

“…Several methods to improve B1 inhomogeneity have been reported and include use of a novel RF transmitter coil system, modiˆed RF pulse sequences, adequate imaging processing after examination, and dielectric material around objects during examination. 2,3,7,8 We have reported an original method to develop a dielectric-equivalent gel with better impedance matching for human skin. 6,7 Use of the gel between an object and the receiver coil during MR scanning can improve B1 inhomogeneity in a high-tesla magneticˆeld by reducing the interference and re‰ection of RF waves at the object's surface.…”

“…2,3,7,8 We have reported an original method to develop a dielectric-equivalent gel with better impedance matching for human skin. 6,7 Use of the gel between an object and the receiver coil during MR scanning can improve B1 inhomogeneity in a high-tesla magneticˆeld by reducing the interference and re‰ection of RF waves at the object's surface. In this study, we assessed the eŠect of our home-made gel pad using a plastic-bottle phantom on a 3T MR system.…”

Candidate for Tissue Mimicking Material Made of an Epoxy Matrix Loaded With Alginate Microspheres

“…There are materials which contain substances such as honey syrup or egg whites [17,18]. These materials are also proposed as phantom materials because their properties at some frequencies agree with tissue properties.…”