As an emerging molecular imaging modality, cone-beam X-ray luminescence computed tomography (CB-XLCT) uses X-ray-excitable probes to produce near-infrared (NIR) luminescence and then reconstructs three-dimensional (3D) distribution of the probes from surface measurements. A proper photon-transportation model is critical to accuracy of XLCT. Here, we presented a systematic comparison between the common-used Monte Carlo model and simplified spherical harmonics (SPN). The performance of the two methods was evaluated over several main spectrums using a known XLCT material. We designed both a global measurement based on the cosine similarity and a locally-averaged relative error, to quantitatively assess these methods. The results show that the SP3 could reach a good balance between the modeling accuracy and computational e±ciency for all of the tested emission spectrums. Besides, the SP1 (which is equivalent to the diffusion equation (DE)) can be a reasonable alternative model for emission wavelength over 692 nm. In vivo experiment further demonstrates the reconstruction performance of the SP3 and DE. This study would provide a valuable guidance for modeling the photon-transportation in CB-XLCT.

生物发光断层成像(BLT)是一种非常有效的光学分子成像方式，在医学预临床研究中的有着广泛的研究。然而，BLT的核心问题即光源重建仍然存在着巨大的挑战：光在生物组织中的传输模型是否精确与重建问题不适定性都使得光源位置与密度的重建变得十分困难。为了准确高效地实现光源重建，在光传输模型的选择上，通过将扩散近似模型和高阶简化球谐近似模型（SPN）的结果与蒙特卡罗金标准进行比较，结果表明阶次（N）为3时的SP3模型描述光子在生物体的传输时能够最佳地兼顾精度和速度。基于SP3传输模型，结合光源在生物体内稀疏分布的特征，采用变量分离近似稀疏重构（SpaRSA）的方法来解决BLT的重建问题。为了验证提出方法的有效性，通过将数字鼠仿真和真实小鼠实验与典型的l1_ls方法对比表明在SP3模型下SpaRSA算法可行。