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Abstract：
Recently, an acoustic lens has been proposed for volumetric focusing as an alternative to conventional reconstruction algorithms in Photoacoustic (PA) Imaging. Acoustic lens can significantly reduce computational complexity and facilitate the implementation of real-time and cost-effective systems. However, due to the fixed focal length of the lens, the Point Spread Function (PSF) of the imaging system varies spatially. Furthermore, the PSF is asymmetric, with the lateral resolution being lower than the axial resolution. For many medical applications, such as in vivo thyroid, breast and small animal imaging, multiple views of the target tissue at varying angles are possible. This can be exploited to reduce the asymmetry and spatial variation of system the PSF with simple spatial compounding. In this article, we present a formulation and experimental evaluation of this technique. PSF improvement in terms of resolution and Signal to Noise Ratio (SNR) with the proposed spatial compounding is evaluated through simulation. Overall image quality improvement is demonstrated with experiments on phantom and ex vivo tissue. When multiple views are not possible, an alternative residual refocusing algorithm is proposed. The performances of these two methods, both separately and in conjunction, are compared and their practical implications are discussed.
摘要：
最近,已经提出了用于体积聚焦的声透镜作为光声(PA)成像中的常规重建算法的替代方案。声透镜可以显着降低计算复杂性，并有助于实现实时和具有成本效益的系统。然而,由于镜头的焦距固定，成像系统的点扩散函数(PSF)在空间上变化。此外，PSF是不对称的，横向分辨率低于轴向分辨率。对于许多医疗应用，如体内甲状腺，乳房和小动物成像，目标组织在不同角度的多个视图是可能的。这可以利用简单的空间复合来减少系统PSF的不对称性和空间变化。在这篇文章中,我们提出了该技术的配方和实验评估。通过仿真评估了所提出的空间复合在分辨率和信噪比（SNR）方面的PSF改善。通过对体模和离体组织的实验证明了整体图像质量的改善。当多个视图是不可能的，提出了一种替代的残差重聚焦算法。这两种方法的性能，无论是单独还是连带，进行了比较，并讨论了它们的实际意义。
