Novel Tissue-Mimicking Material for Phantoms Fabricated from Swollen Segmented Polyurethane Gel with Low Ultrasonic Propagation Loss

Herein, we present a tissue-mimicking material (TMM) for phantoms used in medical diagnostic instruments. Accurate testing of an instrument by phantoms requires a TMM whose sound velocity, characteristic acoustic impedance, and attenuation is as per the International Electrotechnical Commission (IEC) standard. Furthermore, the TMM must be stable over time. Accordingly, we have developed a new permanent gel that allows a wide range of sound speeds to be set by controlling the type and volume of liquid with little attenuation. We found two types of liquids and liquid compositions that can be used for the gels in order to achieve low attenuation, and we developed a TMM with polymer particles blended into the gel to adjust its attenuation to meet IEC standards. Specifically, the gel consists of a swollen segmented polyurethane gel with triethylene glycol dimethyl ether and N-methyl-2-pyrrolidone as media. The TMM is prepared from the permanently swollen segmented polyurethane gel dispersed with highly cross-linked poly(methyl methacrylate) particles. This TMM has more desirable features than agar-based gels, such as the liquid being less prone to evaporation, fracture, and putrefaction.