Sassaroli Angelo, Blaney Giles, Fantini Sergio
J Opt Soc Am A Opt Image Sci Vis. 2019 Oct 1;36(10):1743-1761. doi: 10.1364/JOSAA.36.001743.
Using diffusion theory, we show that a dual-slope method is more effective than single-slope methods or single-distance methods at enhancing sensitivity to deeper tissue. The dual-slope method requires a minimum of two sources and two detectors arranged in specially configured arrays. In particular, we present diffusion theory results for a symmetrical linear array of two sources (separated by 55 mm) that sandwich two detectors (separated by 15 mm), for which dual slopes achieve maximal sensitivity at a depth of about 5 mm for direct current (DC) intensity (as measured in continuous-wave spectroscopy) and 11 mm for phase (as measured in frequency-domain spectroscopy) under typical values of the tissue optical properties (absorption coefficient: ∼0.01, reduced scattering coefficient: ∼1). This result is a major advance over single-distance or single-slope data, which feature maximal sensitivity to shallow tissue (<2 for the intensity, <5 for the phase).
利用扩散理论，我们表明，在增强对更深层组织的敏感性方面，双斜率方法比单斜率方法或单距离方法更有效。双斜率方法至少需要两个源和两个探测器，以特殊配置的阵列排列。具体而言，我们给出了两个源（相距55毫米）夹着两个探测器（相距15毫米）的对称线性阵列的扩散理论结果，在典型的组织光学特性值（吸收系数：约0.01，约化散射系数：约1）下，对于直流（DC）强度（如在连续波光谱中测量），双斜率在约5毫米深度处实现最大灵敏度，对于相位（如在频域光谱中测量），在11毫米深度处实现最大灵敏度。这一结果相对于单距离或单斜率数据有了重大进展，单距离或单斜率数据对浅层组织的灵敏度最高（强度<2，相位<5）。
