基于非接触SPAD测量的时间分辨漫射光学模拟器系统验证
Systematic validation of time-resolved diffuse optical simulators via non-contact SPAD-based measurements
AI总结：
本研究针对时域漫射光学成像模拟器缺乏非接触场景实验验证的问题，基于SPAD阵列实测数据评估三款开源模拟器性能，给出选型指南并验证了虚源校正的有效性。
摘要：
研究目标：时域漫射光学成像（DOI）需要散射介质中光子传播的精确正向模型，但现有模拟器缺乏全面的实验验证，尤其是斜向照明的非接触配置场景。本研究利用时间分辨实验数据严格评估了MMC、NIRFASTer和Toast++三款广泛使用的开源模拟器。研究方法：所有仿真采用统一网格与点光源照明，对有限元法（FEM）求解器施加斜入射虚源校正；搭载32×32单光子雪崩二极管（SPAD）阵列的时间分辨DOI系统，从16个吸收系数μₐ、约化散射系数μₛ′各不相同的标准化仿体采集透射模式数据；从空间域（SD）精度、时域（TD）精度、斜光束精度、计算速度、网格密度无关性五个指标量化仿真结果。研究结果：三款模拟器中，MMC在空间域与时域指标上精度最优，在所有光学属性下均表现出鲁棒性；NIRFASTer与Toast++整体性能相当。总体而言，MMC最适合精度要求高的时域DOI应用，NIRFASTer与Toast++则适用于μₛ′足够大且优先考虑速度的场景。此外，虚源校正对非接触有限元建模至关重要，在大角度场景下可将平均误差降低34%以上。研究意义：本工作为下一代时域DOI系统开发阶段的模拟器选择提供了基准指导，是首个在临床相关非接触条件下基于SPAD阵列数据系统验证时域模拟器的研究，填补了生物医学光学仿真标准的关键空白。
英文摘要：
Objective: Time-domain diffuse optical imaging (DOI) requires accurate forward models for photon propagation in scattering media. However, existing simulators lack comprehensive experimental validation, especially for non-contact configurations with oblique illumination. This study rigorously evaluates three widely used open-source simulators, including MMC, NIRFASTer, and Toast++, using time-resolved experimental data. Approach: All simulations employed a unified mesh and point-source illumination. Virtual source correction was applied to FEM solvers for oblique incidence. A time-resolved DOI system with a 32 $\times$ 32 single-photon avalanche diode (SPAD) array acquired transmission-mode data from 16 standardized phantoms with varying absorption coefficient $μ_a$ and reduced scattering coefficient $μ_s'$. The simulation results were quantified across five metrics: spatial-domain (SD) precision, time-domain (TD) precision, oblique beam accuracy, computational speed, and mesh-density independence. Results: Among three simulators, MMC achieves superior accuracy in SD and TD metrics, and shows robustness across all optical properties. NIRFASTer and Toast++ demonstrate comparable overall performance. In general, MMC is optimal for accuracy-critical TD-DOI applications, while NIRFASTer and Toast++ suit scenarios prioritizing speed with sufficiently large $μ_s'$. Besides, virtual source correction is essential for non-contact FEM modeling, which reduced average errors by > 34% in large-angle scenarios. Significance: This work provides benchmarked guidelines for simulator selection during the development phase of next-generation TD-DOI systems. Our work represents the first study to systematically validate TD simulators against SPAD array-based data under clinically relevant non-contact conditions, bridging a critical gap in biomedical optical simulation standards.
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