Dielectric properties of gelatine phantoms used for simulations of biological tissues between 10 and 50 MHz

Abstract

The use of gelatine phantoms for simulating the dielectric properties of human tissues is suggested. These phantoms are mainly made of gelatine and water and are therefore readily prepared at a low cost. They can be poured into moulds and adopt various shapes depending on the organ to be simulated. In addition, their preservation is not critical. We have studied, at 10, 27 and 50 MHz, the variations of relative permittivity and conductivity as a function of temperature between 15 and 50 degrees C. What is shown is that those values vary both as a function of gelatine concentrations and as a function of temperature. For example, at 37 degrees C and 27 MHz, variations of relative permittivity from 87 to 100 and variations of the conductivity from 0.27 to 0.45 S/m for concentrations of 10% to 40% are observed. At the above frequency, the permittivity of human and animal tissues range between 95 and 180 and the conductivity between 0.4 and 0.6 S/m. Furthermore, the addition of sodium chloride at variable concentrations enables both conductivity and permittivity values to be modified. We propose, as 'muscle-equivalent' phantoms at 27 MHz, a phantom consisting of 20% gelatine with an electrical conductivity from 0.27 to 0.48 S/m and a relative permittivity from 90 to 93 at temperatures between 15 and 50 degrees C. These gelatine, water and sodium chloride phantoms are adapted for easy and cheap simulation of most human tissues in a temperature range from 15 to 50 degrees C, for frequencies from 10 to 50 MHz.