Significance: Coherence, a fundamental property of waves and fields, plays a key role in photoacoustic image reconstruction. Previously, techniques such as short-lag spatial coherence (SLSC) and filtered delay, multiply, and sum (FDMAS) have utilized spatial coherence to improve the reconstructed resolution and contrast with respect to delay-and-sum (DAS). While SLSC uses spatial coherence directly as the imaging contrast, FDMAS employs spatial coherence implicitly. Despite being more robust against noise, both techniques have their own drawbacks: SLSC does not preserve a relative signal magnitude, and FDMAS shows a reduced contrast-to-noise ratio. Aim: To overcome these limitations, our aim is to develop a beamforming algorithm—generalized spatial coherence (GSC)—that unifies SLSC and FDMAS into a single equation and outperforms both beamformers. Approach: We demonstrated the application of GSC in photoacoustic computed tomography (PACT) through simulation and experiments and compared it to previous beamformers: DAS, FDMAS, and SLSC. Results: GSC outperforms the imaging metrics of previous state-of-the-art coherence-based beamformers in both simulation and experiments. Conclusions: GSC is an innovative reconstruction algorithm for PACT, which combines the strengths of FDMAS and SLSC expanding PACT’s applications.

中文翻译：

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光声计算机断层扫描的广义空间相干重建

意义：相干性是波和场的基本属性，在光声图像重建中起着关键作用。以前，诸如短滞后空间相干性 (SLSC) 和滤波延迟、乘法和求和 (FDMAS) 等技术已经利用空间相干性来提高重构的分辨率和相对于延迟求和 (DAS) 的对比度。SLSC 直接使用空间相干性作为成像对比度，而 FDMAS 隐含地使用了空间相干性。尽管对噪声更加鲁棒，但这两种技术都有其自身的缺点：SLSC 不保留相对信号幅度，并且 FDMAS 显示降低的对比度噪声比。目标：为了克服这些限制，我们的目标是开发一种波束形成算法——广义空间相干性 (GSC)——将 SLSC 和 FDMAS 统一到一个方程中，并优于这两种波束形成器。方法：我们通过模拟和实验展示了 GSC 在光声计算机断层扫描 (PACT) 中的应用，并将其与之前的波束形成器：DAS、FDMAS 和 SLSC 进行了比较。结果：GSC 在模拟和实验中都优于以前最先进的基于相干的波束形成器的成像指标。结论：GSC 是一种创新的 PACT 重建算法，它结合了 FDMAS 和 SLSC 的优势，扩展了 PACT 的应用。