Yuan Yu, Zhao Yue, Zhang Nuomin, Xiao Yang, Jin Jing, Feng Naizhang, Shen Yi
Control Theory and Engineering, School of Astronautics, Harbin Institute of Technology, Harbin, China.
Control Theory and Engineering, School of Astronautics, Harbin Institute of Technology, Harbin, China.
Ultrasound Med Biol. 2023 May;49(5):1070-1081. doi: 10.1016/j.ultrasmedbio.2022.12.004. Epub 2023 Feb 1.
The objective of the work described here was to incorporate the spatial shapes of the transducer elements into the framework of the full-waveform inversion.
An element is treated as its cross-section in the 2-D imaging plane, that is, a line segment. The elements are not simply modeled as a set of point sources on their surface to avoid staircasing artifacts. By use of the Fourier collocation method, an element is spatially represented as the discrete convolution between its spatial distribution and a band-limited delta function. The excitation pulses on the emitters and recorded signals on the receivers are then weighted based on the discrete convolution results. Digital and physical experiments are implemented to validate the method.
It is meaningful to model the shapes of the elements if their spatial sizes are similar to or larger than the acoustic wavelengths. It should, however, be noted that because this article focuses on 2-D imaging, the inter-plane effects are not considered.
The approach helps reduce the root mean square errors and increase the structural similarity of the reconstructed images. It also helps to improve the stability of convergence and to accelerate the convergence speed.
本文所述工作的目的是将换能器元件的空间形状纳入全波形反演框架。
在二维成像平面中，将元件视为其横截面，即一条线段。为避免阶梯状伪影，元件并非简单地建模为其表面上的一组点源。通过使用傅里叶配置法，元件在空间上表示为其空间分布与带限狄拉克函数之间的离散卷积。然后根据离散卷积结果对发射器上的激励脉冲和接收器上记录的信号进行加权。进行了数字和物理实验以验证该方法。
如果元件的空间尺寸与声波波长相似或大于声波波长，则对元件形状进行建模是有意义的。然而，应注意的是，由于本文专注于二维成像，未考虑平面间效应。
该方法有助于降低均方根误差，提高重建图像的结构相似性。它还有助于提高收敛稳定性并加快收敛速度。
