Dual shear wave induced laser speckle contrast signal and the improvement in shear wave speed measurement.
Dual shear wave induced laser speckle contrast signal and the improvement in shear wave speed measurement.
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DOI：
10.1364/boe.6.001954
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发表时间：
2015-06
影响因子：
3.4
通讯作者：
Sinan Li;Yi Cheng;R. Eckersley;D. Elson;M. Tang
中科院分区：
文献类型：
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作者：
Sinan Li;Yi Cheng;R. Eckersley;D. Elson;M. Tang
剪切波速与组织粘弹性有定量关系。在此之前，我们报道了使用激光散斑对比度检测来跟踪混浊光学介质中厘米深度的横波。剪切波级数调制了光学散射体的位移，从而调制了光子相位，改变了激光散斑图案。基于时间分辨电荷耦合器件(CCD)的散斑对比度分析用于跟踪横波和测量横波的飞行时间，用于速度测量。在本文中，我们报道了对双横波激光散斑对比度差信号的新观测。观察到了一种调制的CCD散斑对比度差，模拟再现了调制图案，推测了它的起源。实验和仿真结果都表明，双剪切波方法改善了飞行时间光信号的时间特征清晰度，提高了信噪比，其标准偏差小于单剪切波的50%。研究结果还表明，双横波能有效地校正由弹性边界的横波反射引起的横波速度测量偏差。
Shear wave speed is quantitatively related to tissue viscoelasticity. Previously we reported shear wave tracking at centimetre depths in a turbid optical medium using laser speckle contrast detection. Shear wave progression modulates displacement of optical scatterers and therefore modulates photon phase and changes the laser speckle patterns. Time-resolved charge-coupled device (CCD)-based speckle contrast analysis was used to track shear waves and measure the time-of-flight of shear waves for speed measurement. In this manuscript, we report a new observation of the laser speckle contrast difference signal for dual shear waves. A modulation of CCD speckle contrast difference was observed and simulation reproduces the modulation pattern, suggesting its origin. Both experimental and simulation results show that the dual shear wave approach generates an improved definition of temporal features in the time-of-flight optical signal and an improved signal to noise ratio with a standard deviation less than 50% that of individual shear waves. Results also show that dual shear waves can correct the bias of shear wave speed measurement caused by shear wave reflections from elastic boundaries.