Guenther Drake A, Walker William F
Department of Biomedical Engineering, University of Virginia, 415 Lane Road, Charlottesville, VA 22908, USA.
Ultrasonics. 2009 May;49(4-5):404-12. doi: 10.1016/j.ultras.2008.10.010. Epub 2008 Oct 30.
This paper presents a new approach to improve the in silico modeling of ultrasound transducer arrays. While current simulation tools accurately predict the theoretical element spatio-temporal pressure response, transducers do not always behave as theorized. In practice, using the probe's physical dimensions and published specifications in silico, often results in unsatisfactory agreement between simulation and experiment. We describe a general optimization procedure used to maximize the correlation between the observed and simulated spatio-temporal response of a pulsed single element in a commercial ultrasound probe. A linear systems approach is employed to model element angular sensitivity, lens effects, and diffraction phenomena. A numerical deconvolution method is described to characterize the intrinsic electro-mechanical impulse response of the element. Once the response of the element and optimal element characteristics are known, prediction of the pressure response for arbitrary apertures and excitation signals is performed through direct convolution using available tools. We achieve a correlation of 0.846 between the experimental emitted waveform and simulated waveform when using the probe's physical specifications in silico. A far superior correlation of 0.988 is achieved when using the optimized in silico model. Electronic noise appears to be the main effect preventing the realization of higher correlation coefficients. More accurate in silico modeling will improve the evaluation and design of ultrasound transducers as well as aid in the development of sophisticated beamforming strategies.
本文提出了一种改进超声换能器阵列计算机模拟的新方法。虽然当前的模拟工具能够准确预测理论上的元件时空压力响应，但换能器的实际表现并不总是与理论一致。在实际应用中，在计算机模拟中使用探头的物理尺寸和已公布的规格，往往会导致模拟结果与实验结果之间的一致性不尽人意。我们描述了一种通用的优化程序，用于最大化商用超声探头中脉冲单元素的观测时空响应与模拟时空响应之间的相关性。采用线性系统方法对元件角度灵敏度、透镜效应和衍射现象进行建模。描述了一种数值反卷积方法来表征元件的固有机电脉冲响应。一旦知道了元件的响应和最佳元件特性，就可以使用现有工具通过直接卷积对任意孔径和激励信号的压力响应进行预测。当在计算机模拟中使用探头的物理规格时，我们在实验发射波形和模拟波形之间实现了0.846的相关性。当使用优化的计算机模拟模型时，相关性达到了远高于此的0.988。电子噪声似乎是阻碍实现更高相关系数的主要因素。更精确的计算机模拟将改善超声换能器的评估和设计，并有助于开发复杂的波束形成策略。
