Xiao Jiaying, Xiao Mengdi, Wang Bo, Huang Zhongchao, Peng Kuan
Department of Biomedical Engineering, School of Basic Medical Science, Central South University, Changsha 410083, China.
College of Biology, Hunan University, Changsha 410082, China.
Quant Imaging Med Surg. 2018 Dec;8(11):1084-1094. doi: 10.21037/qims.2018.12.07.
Simulation of the emitted acoustic field is crucial to the design of ultrasound transducers. The method based on the spatial impulse response (SIR) and aperture discretization provides a powerful tool to study the acoustic field emitted by a transducer with complex aperture geometry and sophisticated apodization/excitation pattern.
In this work, a new method based on the dynamically refined sub-elements (SE) is employed to discrete the aperture and generate the SIR. Then, these SIRs are convoluted with the excitation pulse to get the acoustic pressure (AP) signal. When calculating the SIR with this method, the slowly changed time flight from a SE to a field point (FP) is approximated with a step function, and the fast changed length of intersection between a SE and a spherical wave centered at a FP is accurately estimated with the areas of the sub-parts (SP) which are given by the dynamically refined SE.
Simulations of the acoustic field created by a focusing transducer array and a hollow structured point focusing transducer indicate that the proposed new method can give similar data accuracy with a sampling frequency 16 times lower than the conventional time tracing SE (TTSE) based method. The computational cost is also reduced by nearly one order of magnitude.
A new method is proposed to simulate the acoustic field emitted by transducers with complex geometrical structure and sophisticated apodization/excitation patterns. The required sampling frequency with the new algorithm is greatly reduced compared to that of the conventional TTSE-based method; thus, the efficiency of the acoustic field calculation is improved significantly.
发射声场的模拟对于超声换能器的设计至关重要。基于空间脉冲响应（SIR）和孔径离散化的方法为研究具有复杂孔径几何形状和复杂变迹/激励模式的换能器所发射的声场提供了一个强大的工具。
在这项工作中，采用了一种基于动态细化子单元（SE）的新方法来离散孔径并生成SIR。然后，将这些SIR与激励脉冲进行卷积以获得声压（AP）信号。用该方法计算SIR时，从一个SE到一个场点（FP）的缓慢变化的飞行时间用阶跃函数近似，并且一个SE与以一个FP为中心的球面波之间相交的快速变化长度用由动态细化SE给出的子部分（SP）的面积精确估计。
对聚焦换能器阵列和空心结构点聚焦换能器产生的声场进行模拟表明，所提出的新方法在采样频率比传统的基于时间追踪SE（TTSE）的方法低16倍的情况下，能给出相似的数据精度。计算成本也降低了近一个数量级。
提出了一种新方法来模拟具有复杂几何结构和复杂变迹/激励模式的换能器所发射的声场。与传统的基于TTSE的方法相比，新算法所需的采样频率大大降低；因此，显著提高了声场计算的效率。
