Light scattering by tissue severely limits how deep beneath the surface one can image, and the spatial resolution one can obtain from these images. Diffuse optical tomography (DOT) is one of the most powerful techniques for imaging deep within tissue – well beyond the conventional $\sim$ 10-15 mean scattering lengths tolerated by ballistic imaging techniques such as confocal and two-photon microscopy. Unfortunately, existing DOT systems are limited, achieving only centimeter-scale resolution. Furthermore, they suffer from slow acquisition times and slow reconstruction speeds making real-time imaging infeasible. We show that time-of-flight diffuse optical tomography (ToF-DOT) and its confocal variant (CToF-DOT), by exploiting the photon travel time information, allow us to achieve millimeter spatial resolution in the highly scattered diffusion regime ( $> \!\!50$ mean free paths). In addition, we demonstrate two additional innovations: focusing on confocal measurements, and multiplexing the illumination sources allow us to significantly reduce the measurement acquisition time. Finally, we rely on a novel convolutional approximation that allows us to develop a fast reconstruction algorithm, achieving a 100× speedup in reconstruction time compared to traditional DOT reconstruction techniques. Together, we believe that these technical advances serve as the first step towards real-time, millimeter resolution, deep tissue imaging using DOT.

中文翻译：

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使用共焦飞行时间漫反射光学断层扫描的高分辨率深度成像

组织的光散射严重限制了人们可以在表面下方成像的深度，以及人们可以从这些图像中获得的空间分辨率。漫射光学断层扫描 (DOT) 是用于在组织深处成像的最强大的技术之一 - 远远超出了传统的$\sim$ 弹道成像技术（例如共焦和双光子显微镜）可容忍的平均散射长度为 10-15。不幸的是，现有的 DOT 系统是有限的，只能实现厘米级的分辨率。此外，它们遭受缓慢的采集时间和缓慢的重建速度，使得实时成像不可行。我们表明，通过利用光子传播时间信息，飞行时间漫反射光学断层扫描 (ToF-DOT) 及其共焦变体 (CToF-DOT) 使我们能够在高度散射的扩散状态下实现毫米空间分辨率。 $> \!\!50$表示自由路径）。此外，我们展示了两项额外的创新：专注于共焦测量，以及多路复用照明源使我们能够显着减少测量采集时间。最后，我们依靠一种新颖的卷积近似，使我们能够开发一种快速的重建算法，与传统的 DOT 重建技术相比，重建时间提高了 100 倍。总之，我们相信这些技术进步是使用 DOT 实现实时、毫米分辨率、深部组织成像的第一步。