Photoacoustic imaging (PAI) is susceptible to speed of sound (SOS) differences in heterogeneous media which greatly reduce the resolutions and qualities of the imaging results. Several reconstruction methods have been reported to adapt for heterogenous media, but they are limited by specific deficiencies such as efficiency, accuracy, and model limitation problems. Among them, the plane wave model based on wavefield reconstruction is the most efficient and promising one for high-efficiency three-dimensional PAI. However, the classic plane wave model only suits for planar layered media, severely limiting its applications in practice. To this end, we modify the plane wave model to apply for irregularly layered heterogeneous media and propose a corresponding wavefield extrapolation to reconstruct photoacoustic image. This method employs split-step Fourier to compensate the SOS differences, extrapolates wavefields and reconstructs the image depth by depth. Furthermore, a floating discretization strategy is introduced to control and balance the efficiency and accuracy with a hyperparameter. The simulation and experiment results demonstrate that the proposed method can reconstruct the image with an equivalent resolution to time reversal's and even have higher efficiency and robustness. To reconstruct a three-dimensional image with 50×50×600 pixels, the proposed method takes only 5.5 seconds using a laptop loaded with Intel(R) Core (TM) i7-8550U CPU @1.8GHz.

中文翻译：

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不规则分层异质介质的快速三维光声成像重建。

光声成像（PAI）易受异质介质中声速（SOS）差异的影响，这大大降低了成像结果的分辨率和质量。据报道，有几种重建方法适用于异构媒体，但是它们受到诸如效率，准确性和模型限制问题之类的特定缺陷的限制。其中，基于波场重构的平面波模型是高效三维PAI的最有效，最有前途的模型。但是，经典的平面波模型仅适用于平面分层介质，严重限制了其在实践中的应用。为此，我们修改了平面波模型以适用于不规则分层的非均质介质，并提出了相应的波场外推法来重建光声图像。该方法采用分步傅里叶补偿SOS差异，外推波场并按深度重建图像深度。此外，引入了浮动离散化策略来控制和平衡具有超参数的效率和准确性。仿真和实验结果表明，所提出的方法能够以与时间反转等效的分辨率重建图像，甚至具有更高的效率和鲁棒性。为了重建具有50×50×600像素的三维图像，使用装有Intel®Core（TM）i7-8550U CPU @ 1.8GHz的笔记本电脑，提出的方法仅需5.5秒。引入了浮动离散化策略，以通过超参数控制和平衡效率和准确性。仿真和实验结果表明，所提出的方法能够以与时间反转等效的分辨率重建图像，甚至具有更高的效率和鲁棒性。为了重建具有50×50×600像素的三维图像，使用装有Intel®Core（TM）i7-8550U CPU @ 1.8GHz的笔记本电脑，提出的方法仅需5.5秒。引入了浮动离散化策略，以通过超参数控制和平衡效率和准确性。仿真和实验结果表明，所提出的方法能够以与时间反转等效的分辨率重建图像，甚至具有更高的效率和鲁棒性。为了重建具有50×50×600像素的三维图像，使用装有Intel®Core（TM）i7-8550U CPU @ 1.8GHz的笔记本电脑，提出的方法仅需5.5秒。