Photoacoustic tomography (PAT) is a non-invasive, high-resolution imaging modality, capable of providing functional and molecular information of various pathologies, such as cancer. One limitation of PAT is the depth and wavelength dependent optical fluence, which results in reduced PA signal amplitude from deeper tissue regions. These factors can therefore introduce errors into quantitative measurements such as oxygen saturation (sO₂) or the localization and concentration of various chromophores. The variation in the speed-of-sound between different tissues can also lead to distortions in object location and shape. Compensating for these effects allows PAT to be used more quantitatively. We have developed a proof-of-concept algorithm capable of compensating for the heterogeneity in speed-of-sound and depth dependent optical fluence. Speed-of-sound correction was done by using a straight ray-based algorithm for calculating the family of iso-time-of-flight contours between the transducers and every pixel in the imaging grid, while fluence compensation was done by utilizing the graphics processing unit (GPU) accelerated software MCXCL for Monte Carlo modeling of optical fluence variation. This algorithm was tested on a polyvinyl chloride plastisol (PVCP) phantom, which contained cyst mimics and blood inclusions to test the algorithm under relatively heterogeneous conditions. Our results indicate that our PAT algorithm can compensate for the speed-of-sound variation and depth dependent fluence effects within a heterogeneous phantom. The results of this study will pave the way for further development and evaluation of the proposed method in more complex in-vitro and ex-vivo phantoms, as well as compensating for the wavelength-dependent optical fluence in spectroscopic PAT.

光声层析成像（PAT）是一种非侵入性的高分辨率成像方式，能够提供各种病理学（例如癌症）的功能和分子信息。PAT的局限性之一是与深度和波长有关的光学能量密度，这会导致来自较深组织区域的PA信号幅度降低。因此，这些因素会将误差引入定量测量中，例如氧饱和度（sO ₂）或各种发色团的定位和浓度。不同组织之间的音速变化也可能导致物体位置和形状变形。补偿这些影响可以使PAT更定量地使用。我们已经开发了一种概念证明算法，能够补偿音速和深度相关的光学通量的异质性。通过使用基于直射线的算法来计算声速校正，以计算换能器与成像网格中每个像素之间的等速飞行等高线族，而通量补偿则通过利用图形处理来完成单元（GPU）加速软件MCXCL，用于光学通量变化的蒙特卡洛建模。该算法已在聚氯乙烯增塑溶胶（PVCP）体模上进行了测试，其中包含囊肿模拟物和血液包裹体，以在相对异构的条件下测试该算法。我们的结果表明，我们的PAT算法可以补偿异类体模中的音速变化和与深度相关的注量效应。这项研究的结果将为进一步开发和评估更复杂的提议方法铺平道路。体外和离体幻像，以及补偿光谱PAT中依赖于波长的光学通量。