Significance: Photoacoustic tomography (PAT) is a promising emergent modality for the screening and staging of breast cancer. To minimize barriers to clinical translation, it is common to develop PAT systems based upon existing ultrasound hardware, which can entail significant design challenges in terms of light delivery. This often results in inherently non-uniform fluence within the tissue and should be accounted for during image reconstruction. Aim: We aim to integrate PAT into an automated breast ultrasound scanner with minimal change to the existing system. Approach: We designed and implemented an illuminator that directs spatially non-uniform light to the tissue near the acquisition plane of the imaging array. We developed a graphics processing unit-accelerated reconstruction method, which accounts for this illumination geometry by modeling the structure of the light in the sample. We quantified the performance of this system using a custom, modular photoacoustic phantom and graphite rods embedded in chicken breast tissue. Results: Our illuminator provides a fluence of 2.5 mJ cm − 2 at the tissue surface, which was sufficient to attain a signal-to-noise ratio (SNR) of 8 dB at 2 cm in chicken breast tissue and image 0.25-mm features at depths of up to 3 cm in a medium with moderate optical scattering. Our reconstruction scheme is 200 × faster than a CPU implementation; it provides a 25% increase in SNR at 2 cm in chicken breast tissue and lowers image error by an average of 31% at imaging depths >1.5 cm compared with a method that does not account for the inhomogeneity of the illumination or the transducer directivity. Conclusions: A fan-shaped illumination geometry is feasible for PAT; however, it is important to account for non-uniform fluence in illumination scenarios such as this. Future work will focus on increasing fluence and further optimizing the ultrasound hardware to improve SNR and overall image quality.

中文翻译：

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将光声断层扫描集成到多模式自动乳腺超声扫描仪中

意义：光声断层扫描（PAT）是一种很有前途的乳腺癌筛查和分期的新兴方式。为了最大限度地减少临床转化的障碍，开发基于现有超声硬件的 PAT 系统是很常见的，这可能会带来光传输方面的重大设计挑战。这通常会导致组织内固有的非均匀通量，应在图像重建过程中加以考虑。目标：我们的目标是将 PAT 集成到自动化乳房超声扫描仪中，对现有系统进行最小的改动。方法：我们设计并实施了一种照明器，可将空间非均匀光引导到成像阵列采集平面附近的组织。我们开发了一种图形处理单元加速重建方法，它通过对样本中的光结构进行建模来解释这种照明几何结构。我们使用嵌入鸡胸组织的定制模块化光声幻影和石墨棒来量化该系统的性能。结果：我们的照明器在组织表面提供了 2.5 mJ cm - 2 的能量密度，这足以在鸡胸组织中在 2 cm 处获得 8 dB 的信噪比 (SNR) 并在 0.25 mm 处成像在中等光学散射的介质中深度可达 3 cm。我们的重建方案比 CPU 实现快 200 倍；与不考虑照明不均匀性或换能器方向性的方法相比，它在鸡胸组织中 2 cm 处提供了 25% 的 SNR 增加，并在成像深度 >1.5 cm 处将图像误差平均降低了 31%。结论：扇形照明几何结构对于 PAT 是可行的；然而，重要的是要考虑到这种照明场景中的非均匀注量。未来的工作将集中在增加通量和进一步优化超声硬件以提高 SNR 和整体图像质量。