Department of Electrical and Computer Engineering, Northeastern University, Boston, MA 02115, USA.
IEEE Trans Ultrason Ferroelectr Freq Control. 2009 Sep;56(9):1903-12. doi: 10.1109/TUFFC.2009.1266.
A fast method for computing the acoustic field of ultrasound transducers is presented with application to rectangular elements that are cylindrically focused. No closed-form solutions exist for this case but several numerical techniques have been described in the ultrasound imaging literature. Our motivation is the rapid calculation of imaging kernels for physics-based diagnostic imaging for which current methods are too computationally intensive. Here, the surface integral defining the acoustic field from a baffled piston is converted to a 3-D spatial convolution of the element surface and the Green's function. A 3-D version of the overlap-save method from digital signal processing is employed to obtain a fast computational algorithm based on spatial Fourier transforms. Further efficiency is gained by using a separable approximation to the Green's function through singular value decomposition and increasing the effective sampling rate by polyphase filtering. The tradeoff between accuracy and spatial sampling rate is explored to determine appropriate parameters for a specific transducer. Comparisons with standard tools such as Field II are presented, where nearly 2 orders of magnitude improvement in computation speed is observed for similar accuracy.
提出了一种快速计算超声换能器声场的方法，应用于圆柱聚焦的矩形单元。对于这种情况，不存在封闭形式的解，但在超声成像文献中已经描述了几种数值技术。我们的动机是快速计算基于物理的诊断成像的成像核，当前的方法计算量太大。在这里，从带挡板活塞定义声场的表面积分转换为元件表面和格林函数的 3-D 空间卷积。采用数字信号处理中的重叠保存方法的 3-D 版本，基于空间傅里叶变换获得快速计算算法。通过奇异值分解对格林函数进行可分离近似，并通过多相滤波增加有效采样率，从而进一步提高效率。探索了准确性和空间采样率之间的权衡，以确定特定换能器的适当参数。与 Field II 等标准工具进行了比较，在相似的精度下，观察到计算速度提高了近 2 个数量级。
