Excitation of ultrasonic Lamb waves using a phased array system with two array probes: Phantom and in vitro bone studies
Excitation of ultrasonic Lamb waves using a phased array system with two array probes: Phantom and in vitro bone studies
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DOI：
10.1016/j.ultras.2013.08.004
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发表时间：
2014-07-01
期刊：
影响因子：
4.2
通讯作者：
Lou, Edmond H. M.
中科院分区：
文献类型：
--
作者：
Nguyen, Kim-Cuong T.;Le, Lawrence H.;Lou, Edmond H. M.
长骨是支持超声导波传播的良好波导。在定量超声骨研究中一直观察到低阶导波。这些低阶导模的选择性激发需要使用换能器楔系统的超声波束的倾斜入射。通常假设入射角θ（i）通过斯涅耳定律θ（i）= sin（1）（v（w）/c（o））产生感兴趣的特定相速度c（o），其中v（w）是耦合介质的速度。在这项研究中，我们研究了6.3毫米厚的黄铜板和6.5毫米厚的牛骨板使用超声相控阵系统与两个0.75毫米间距的阵列探头内的导波的激励。将五个元件布置为一组，第一组16元件探头用作发射器，64元件探头用作接收器阵列。使用1.6-MHz源信号将波束转向六个角度（0度、20度、30度、40度、50度和60度）。伴随Radon变换算法将时距矩阵映射到频率-相位速度频散面元。通过理论色散曲线对兰姆板模式进行了识别。结果表明，0 °激励产生了许多模式，没有模式歧视和倾斜光束激发的相速度谱的c（o）不对称的扩展。激励区域的宽度随着转向角的增加而减小，从而在大角度下呈现模态选择性。源影响理论的激发函数很好地预测了这些现象。对于两个板，在转向角>= 30度时低阶模式更好地成像。该研究还证明了使用双探头相控阵系统用于未来体内研究的可行性。(C)2013年爱思唯尔B。V.保留所有权利。
Long bones are good waveguides to support the propagation of ultrasonic guided waves. The low-order guided waves have been consistently observed in quantitative ultrasound bone studies. Selective excitation of these low-order guided modes requires oblique incidence of the ultrasound beam using a transducer-wedge system. It is generally assumed that an angle of incidence, theta(i), generates a specific phase velocity of interest, c(o), via Snell's law, theta(i) = sin (1)(v(w)/c(o)) where v(w) is the velocity of the coupling medium. In this study, we investigated the excitation of guided waves within a 6.3-mm thick brass plate and a 6.5-mm thick bovine bone plate using an ultrasound phased array system with two 0.75-mm-pitch array probes. Arranging five elements as a group, the first group of a 16-element probe was used as a transmitter and a 64-element probe was a receiver array. The beam was steered for six angles (0 degrees, 20 degrees, 30 degrees, 40 degrees, 50 degrees, and 60 degrees) with a 1.6-MHz source signal. An adjoint Radon transform algorithm mapped the time-offset matrix into the frequency-phase velocity dispersion panels. The imaged Lamb plate modes were identified by the theoretical dispersion curves. The results show that the 0 degrees excitation generated many modes with no modal discrimination and the oblique beam excited a spectrum of phase velocities spread asymmetrically about c(o). The width of the excitation region decreased as the steering angle increased, rendering modal selectivity at large angles. The phenomena were well predicted by the excitation function of the source influence theory. The low-order modes were better imaged at steering angle >= 30 degrees for both plates. The study has also demonstrated the feasibility of using the two-probe phased array system for future in vivo study. (C) 2013 Elsevier B. V. All rights reserved.