Accurate wave-equation modeling is becoming increasingly important in modern imaging and therapeutic ultrasound methodologies, such as ultrasound computed tomography, optoacoustic tomography, or high-intensity-focused ultrasound. All of them rely on the ability to accurately model the physics of wave propagation, including accurate characterization of the ultrasound transducers, the physical devices that are responsible for generating and recording ultrasound energy. However, existing methods fail to characterize the transducer response with the accuracy required to fully exploit the capabilities of these emerging imaging and therapeutic techniques. Consequently, we have designed a new algorithm for ultrasound transducer calibration and modeling: spatial response identification (SRI). This method introduces a parameterization of the ultrasound transducer and provides a method to calibrate the transducer model using experimental data, based on a formulation of the problem that is completely independent of the discretization chosen for the transducer or the number of parameters used. The proposed technique models the transducer as a linear time-invariant system that is spatially heterogeneous, and identifies the model parameters that are best at explaining the experimental data while honoring the full wave equation. SRI generates a model that can accommodate the complex, heterogeneous spatial response seen experimentally for ultrasound transducers. Experimental results show that SRI outperforms standard methods both in transmission and reception modes. Finally, numerical experiments using full-waveform inversion demonstrate that existing transducer-modeling approaches are insufficient to produce successful reconstructions of the human brain, whereas errors in our SRI algorithm are sufficiently small to allow accurate image reconstructions.

中文翻译：

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灵活准确的超声换能器校准的空间响应识别及其在脑成像中的应用

精确的波方程建模在现代成像和治疗超声方法学中变得越来越重要，例如超声计算机断层扫描，光声断层扫描或高强度聚焦超声。所有这些都依赖于对波传播的物理特性进行准确建模的能力，包括对超声换能器，负责生成和记录超声能量的物理设备的准确表征。但是，现有方法无法以充分利用这些新兴成像和治疗技术的功能所需的精度来表征换能器响应。因此，我们设计了一种用于超声换能器校准和建模的新算法：空间响应识别（SRI）。该方法基于完全不依赖于为换能器选择的离散化或所使用的参数数量的问题的表述，引入了超声换能器的参数化并提供了一种使用实验数据校准换能器模型的方法。所提出的技术将换能器建模为空间异构的线性时不变系统，并确定最能解释实验数据的模型参数，同时尊重全波方程。SRI生成了一个模型，该模型可以适应超声换能器实验上看到的复杂，异构的空间响应。实验结果表明，在传输和接收模式下，SRI均优于标准方法。最后，