Passive acoustic mapping (PAM) is a promising tool for monitoring acoustic cavitation activities in the applications of ultrasound therapy. Data-adaptive beamformers for PAM have better image quality compared to the time exposure acoustics (TEA) algorithms. However, the computational cost of data-adaptive beamformers is considerably expensive. In this work, we develop a deep beamformer based on a generative adversarial network, which can switch between different transducer arrays and reconstruct high-quality PAM images directly from radio frequency ultrasound signals with low computational cost. The deep beamformer was trained on the dataset consisting of simulated and experimental cavitation signals of single and multiple microbubble clouds measured by different (linear and phased) arrays covering 1-15 MHz. We compared the performance of the deep beamformer to TEA and three different data-adaptive beamformers using the simulated and experimental test dataset. Compared with TEA, the deep beamformer reduced the energy spread area by 18.9%-65.0% and improved the image signal-to-noise ratio by 9.3-22.9 dB in average for the different arrays in our data. Compared to the data-adaptive beamformers, the deep beamformer reduced the computational cost by three orders of magnitude achieving 10.5 ms image reconstruction speed in our data, while the image quality was as good as that of the data-adaptive beamformers. These results demonstrated the potential of the deep beamformer for high-resolution monitoring of microbubble cavitation activities for ultrasound therapy.

翻译：被动声学成像（PAM）是监测超声治疗中声空化活动的一种前景广阔的工具。相较于时间曝光声学（TEA）算法，用于PAM的数据自适应波束形成器具有更优的图像质量。然而，数据自适应波束形成器的计算成本相当高昂。在本研究中，我们开发了一种基于生成对抗网络的深度波束形成器，它能够在不同换能器阵列间切换，并以较低计算成本直接从射频超声信号重建高质量的PAM图像。该深度波束形成器在包含模拟和实验空化信号的数据集上进行训练，这些信号由覆盖1-15 MHz的不同（线阵和相控）阵列测量，涉及单泡及多泡云团。我们使用模拟和实验测试数据集，将深度波束形成器的性能与TEA及三种不同的数据自适应波束形成器进行了比较。与TEA相比，深度波束形成器在我们数据的不同阵列上平均将能量扩散面积减少了18.9%-65.0%，并将图像信噪比提高了9.3-22.9 dB。与数据自适应波束形成器相比，深度波束形成器将计算成本降低了三个数量级，在我们的数据中实现了10.5毫秒的图像重建速度，同时图像质量与数据自适应波束形成器相当。这些结果证明了深度波束形成器在超声治疗中用于微泡空化活动高分辨率监测的潜力。