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.

近来，已经提出了用于体积聚焦的声透镜，以代替光声（PA）成像中的常规重建算法。声学透镜可以显着降低计算复杂度，并有助于实施实时且经济高效的系统。但是，由于镜头的固定焦距，成像系统的点扩展功能（PSF）在空间上会变化。此外，PSF是不对称的，其横向分辨率低于轴向分辨率。对于许多医疗应用，例如体内甲状腺，乳腺和小动物成像时，可以以不同角度观察目标组织的多个视图。可以利用此方法通过简单的空间复合来减少PSF系统的不对称性和空间变化。在本文中，我们介绍了该技术的配方和实验评估。通过仿真评估了采用拟议的空间复合技术在分辨率和信噪比（SNR）方面对PSF的改进。幻像和离体组织上的实验证明了整体图像质量的提高。当不可能有多个视图时，提出了一种替代的残差重聚焦算法。比较了这两种方法（分别或联合使用）的性能，并讨论了它们的实际含义。