Fan Weihao, Trobaugh Jason W, Zhang Chengfeng, Yang Dalin, Culver Joseph P, Eggebrecht Adam T
Department of Physics, Washington University, St. Louis, Missouri, USA.
Department of Electrical and Systems Engineering, Washington University, St. Louis, Missouri, USA.
Med Phys. 2025 Feb;52(2):1045-1057. doi: 10.1002/mp.17491. Epub 2024 Nov 4.
Diffuse optical tomography (DOT) provides three-dimensional image reconstruction of chromophore perturbations within a turbid volume. Two leading strategies to optimize DOT image quality include, (i) arrays of regular, interlacing, high-density (HD) grids of sources and detectors with closest spacing less than 15 mm, or (ii) source modulated light of order ∼100 MHz.
However, the general principles for how these crucial design parameters of array density and modulation frequency may interact to provide an optimal system design have yet to be elucidated.
Herein, we systematically evaluated how these design parameters effect image quality via multiple key metrics. Specifically, we simulated 32 system designs with realistic measurement noise and quantified localization error, spatial resolution, signal-to-noise, and localization depth of field for each of ∼85 000 point spread functions in each model.
We found that array density had a far stronger effect on image quality metrics than modulation frequency. Additionally, model fits for image quality metrics revealed that potential improvements diminish with regular arrays denser than 9 mm closest spacing. Further, for a given array density, 300 MHz source modulation provided the deepest reliable imaging compared to other frequencies.
Our results indicate that both array density and modulation frequency affect the spatial sampling of tissue, which asymptotically saturates due to photon diffusivity within a turbid volume. In summary, our results provide comprehensive perspectives for optimizing future DOT system designs in applications from wearable functional brain imaging to breast tumor detection.
扩散光学断层扫描（DOT）可对浑浊介质内发色团扰动进行三维图像重建。优化DOT图像质量的两种主要策略包括：（i）采用规则、交错的高密度（HD）源和探测器网格阵列，其最小间距小于15毫米；或（ii）采用约100兆赫兹量级的源调制光。
然而，阵列密度和调制频率这些关键设计参数如何相互作用以提供最佳系统设计的一般原则尚未阐明。
在此，我们通过多个关键指标系统地评估了这些设计参数如何影响图像质量。具体而言，我们模拟了32种具有实际测量噪声的系统设计，并对每个模型中约85000个点扩散函数的定位误差、空间分辨率、信噪比和定位景深进行了量化。
我们发现，阵列密度对图像质量指标的影响远大于调制频率。此外，图像质量指标的模型拟合表明，对于最小间距小于9毫米的规则阵列，潜在的改进效果会减弱。此外，对于给定的阵列密度，与其他频率相比，300兆赫兹的源调制可提供最深的可靠成像。
我们的结果表明，阵列密度和调制频率都会影响组织的空间采样，由于浑浊介质内的光子扩散率，这种采样会渐近饱和。总之，我们的结果为优化未来DOT系统设计提供了全面的视角，这些设计应用于从可穿戴功能性脑成像到乳腺肿瘤检测等领域。
