Development of silicon-based materials for ultrasound biological phantoms

Ultrasound (US) phantoms are made of materials that mimic acoustic properties of human soft tissue. Ideally, such materials should mimic US velocity (1435 to 1631 m.s^-1), attenuation (0.22 to 1.47 dB.cm^-1MHz^-n with ranging from 1.09 to 1.15), density (916 to 1100 kg.m^-3) and scattering. Many of the tested materials have some of the desired properties like Agar, polyvinyl alcohol gel and polyacrylamide gel, however, they are susceptible to dehydration and biological attacks. This fact imposes a frequent material renewal, being other source for inaccuracies and uncertainties for measurements. Silicone rubbers are stable materials, but present higher attenuation and lower US velocity compared to tissues. This work investigates the mixing of silicone rubber with other substances to bring its properties close to biological tissues, and evaluates its stability along time.