Almasian Mitra, Bosschaart Nienke, van Leeuwen Ton G, Faber Dirk J
University of Amsterdam, Academic Medical Center, Department of Biomedical Engineering and Physics, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands.
University of Twente, MIRA Institute for Biomedical Technology and Technical Medicine, Biomedical Photonic Imaging Group, Zuidhorst ZH263, 7500 AE, Enschede, The Netherlands.
J Biomed Opt. 2015;20(12):121314. doi: 10.1117/1.JBO.20.12.121314.
Optical coherence tomography (OCT) has the potential to quantitatively measure optical properties of tissue such as the attenuation coefficient and backscattering coefficient. However, to obtain reliable values for strong scattering tissues, accurate consideration of the effects of multiple scattering and the nonlinear relation between the scattering coefficient and scatterer concentration (concentration-dependent scattering) is required. We present a comprehensive model for the OCT signal in which we quantitatively account for both effects, as well as our system parameters (confocal point spread function and sensitivity roll-off). We verify our model with experimental data from controlled phantoms of monodisperse silica beads (scattering coefficients between 1 and 30 mm(−1) and scattering anisotropy between 0.4 and 0.9). The optical properties of the phantoms are calculated using Mie theory combined with the Percus–Yevick structure factor to account for concentration-dependent scattering. We demonstrate excellent agreement between the OCT attenuation and backscattering coefficient predicted by our model and experimentally derived values. We conclude that this model enables us to accurately model OCT-derived parameters (i.e., attenuation and backscattering coefficients) in the concentration-dependent and multiple scattering regime for spherical monodisperse samples.
光学相干断层扫描（OCT）有潜力定量测量组织的光学特性，如衰减系数和后向散射系数。然而，为了获得强散射组织的可靠值，需要准确考虑多重散射的影响以及散射系数与散射体浓度之间的非线性关系（浓度依赖性散射）。我们提出了一个用于OCT信号的综合模型，其中我们定量考虑了这两种影响以及我们的系统参数（共焦点扩散函数和灵敏度滚降）。我们用来自单分散二氧化硅珠控制体模（散射系数在1至30 mm⁻¹之间，散射各向异性在0.4至0.9之间）的实验数据验证了我们的模型。使用米氏理论结合珀库斯 - 耶维克结构因子来计算体模的光学特性，以考虑浓度依赖性散射。我们证明了我们模型预测的OCT衰减和后向散射系数与实验得出的值之间具有极好的一致性。我们得出结论，该模型使我们能够在浓度依赖性和多重散射区域中，对球形单分散样品的OCT衍生参数（即衰减和后向散射系数）进行准确建模。
