Narrowband shear wave generation by a finite-amplitude radiation force: The fundamental component
Narrowband shear wave generation by a finite-amplitude radiation force: The fundamental component
复制标题
有限振幅辐射力产生窄带剪切波：基本分量
DOI：
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复制
发表时间：
2008
期刊：
影响因子：
--
通讯作者：
Richard S. C. Cobbold
中科院分区：
文献类型：
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作者：
A. Giannoula;Richard S. C. Cobbold
由两个相交的频率略有不同的准连续波超声光束产生的调制辐射力可以产生低频剪切波的高度局域化源。与大多数其他基于辐射力的方法相比，这些剪切波可以是窄带的。因此，当它们在粘弹性介质中传播时，不同的频率相关效应不会显著影响它们的频谱，从而可以在任何给定的调制频率下确定介质的粘弹性剪切特性。这可以通过跟踪横波相位延迟和振幅在特定距离上的变化来实现。本文探讨了短历时（动态）低频剪切波的传播特性，研究了剪切位移场对激励条件的依赖关系。我们的研究使用了粘弹性介质的近似格林函数，并从理论角度研究了这种波的时空演化。虽然我们的共焦源模型中包含非线性，但本文只研究了基本剪切分量的性质。我们研究了剪切粘度、耦合波、力的空间分布、剪切速度和调制波的持续时间如何影响剪切波的传播。提出了一种估计粘弹性介质剪切粘度的方法。此外，还展示了如何从频率相关的速度和衰减中提取Voigt模型参数。
A highly localized source of low-frequency shear waves can be created by the modulated radiation force resulting from two intersecting quasi-continuous-wave ultrasound beams of slightly different frequencies. In contrast to most other radiation force-based methods, these shear waves can be narrowband. Consequently, different frequency-dependent effects will not significantly affect their spectrum as they propagate within a viscoelastic medium, thereby enabling the viscoelastic shear properties of the medium to be determined at any given modulation frequency. This can be achieved by tracking the shear wave phase delay and change in amplitude over a specific distance. In this paper we explore the properties of short duration (dynamic) low-frequency shear wave propagation and study how the shear displacement field depends on the excitation conditions. Our investigations make use of the approximate Green's functions for viscoelastic media, and the evolution of such waves is studied in the spatioternporal domain from a theoretical perspective. Although nonlinearities are included in our confocal source model, just the properties of the fundamental shear component are examined in this paper. We examine how the shear wave propagation is affected by the shear viscosity, the coupling wave, the spatial distribution of the force, the shear speed, and the duration of the modulated wave. A method is proposed for estimating the shear viscosity of a viscoelastic medium. In addition, it is shown how the Voigt model parameters can be extracted from the frequency-dependent speed and attenuation.
影响因子：
3.5
作者：
Fatemi, M;Greenleaf, JF
通讯作者：
Greenleaf, JF