Development of a tissue-mimicking phantom for evaluating the focusing performance of high intensity focused ultrasound

Obiectives: To develop a tissue mimicking phantom which can be used to evaluate the focusing performance of the HIFU transducer, and the phantom should has the same acoustic characteristic and thermotics characteristic as the biological tissue. Materials and methods: The tissue mimicking phantom was made from water, gelatin, fresh biologic tissue Its ultrasonic parameters (attenuation coefficient) of the phantom was measured by the method of radiation pressure. and thermotics parameters of the phantom, including thermal conductivity, specific heat/fusion point et al were tested under the Measurement meter. The HIFU biological effect of the phantom was evaluated under the Model JC focused ultrasound tumor therapeutic system, developed and produced by Chongqing HIFU Technology Co. Ltd (working frequency: 0.7MHz; acoustic power: 200W; focal distance: 135mm; Acoustic focal region: 3x3x25 cubic mm). Results: The self-made phantom is sable, has smooth and glossy appearance, well-distributed construction, and good elasticity. We measured the followed values for acoustic and thermal properties: density 1049 +/- 2 kg/m(3); attenuation 0.532 +/- 0.017 dB/cm (0.8 MHz), 0.612 +/- 0.021 dB/cm (1.0 MHz); thermal conductivity 0.76 +/- 0.08 W/m/-degrees C; specific heat 3653 143 J/kg-degrees C; fusion point154 +/- 8 degrees C. The BFR induced in the phantom after HIFU exposure was stable in its size and appearance. Conclusion: We produced and improved one tissue mimicking phantom successfully which had semblable ultrasound and thermphysical properties like the soft tissue, and can replace the bovine liver to investigate the HIFU biological effect and to detect the focusing performance of the HIFU energy transducer.