Gelatine-alginate complex gel: a new acoustically tissue-equivalent material.

Methods are described for the preparation of gelatine-alginate complex gels and measurements are reported of certain of their acoustic and physical properties relevant to their use as tissue-equivalent phantoms in medical ultrasonics applications. Speed of sound at 20 degrees C is 1520 ms-1 with a coefficient of +2.6 ms-1/degrees C. Attenuation coefficient in unloaded gel is 0.12 dB cm-1 MHz-1 (varying approximately linearly with frequency) but can readily be increased to at least 0.5 dB cm-1 MHz-1 by loading the gel with polyethylene or lipid microspheres. Volume stability under conditions of water immersion without an impermeable boundary layer is within about +/- 2% over a 300 day period, an improvement by a factor of at least 25 on both simple and cross-linked gelatine gels, and stability against chemical or bacterial degradation can also readily be maintained.