Dayton Paul A, Allen John S, Ferrara Katherine W
Department of Biomedical Engineering, University of California, Davis 95616, USA.
J Acoust Soc Am. 2002 Nov;112(5 Pt 1):2183-92. doi: 10.1121/1.1509428.
High-speed photography of insonified bubbles with a time resolution of 10 ns allows observations of translation due to radiation force, in addition to the visualization of radial oscillations. A modified version of the Rayleigh-Plesset equation is used to estimate the radius-time behavior of insonified microbubbles, and the accuracy of this model is verified experimentally. The translation of insonified microbubbles is calculated using a differential equation relating the acceleration of the bubble to the forces due to acoustic radiation and the drag imposed by the fluid. Simulations and experiments indicate that microbubbles translate significant distances with clinically relevant parameters. A 1.5 micron radius contrast agent can translate over 5 microns during a single 20-cycle, 2.25 MHz, 380 kPa acoustic pulse, achieving velocities over 0.5 m/s. Therefore, radiation force should be considered during an ultrasonic examination because of the possibility of influencing the position and flow velocity of the contrast agents with the interrogating acoustic beam.
对被声辐射的气泡进行时间分辨率为10纳秒的高速摄影，除了能观察到径向振荡外，还能观测到由于辐射力引起的平移。使用瑞利 - 普莱斯方程的修正版本来估计被声辐射的微气泡的半径 - 时间行为，并通过实验验证了该模型的准确性。利用一个将气泡加速度与声辐射力及流体施加的阻力相关联的微分方程来计算被声辐射的微气泡的平移。模拟和实验表明，在临床相关参数下，微气泡能平移相当大的距离。一个半径为1.5微米的造影剂在单个20周期、2.25兆赫兹、380千帕的声脉冲作用下能平移超过5微米，速度超过0.5米/秒。因此，在超声检查期间应考虑辐射力，因为存在用探测声束影响造影剂位置和流速的可能性。
