Wang F, Ding H, Lin F
Department of Electrical Engineering and Applied Electronics, Tsinghua University, 100084 Beijing.
Guang Pu Xue Yu Guang Pu Fen Xi. 2000 Aug;20(4):585-8.
Based on the modified Lambert-Beer law under scattering media, near infra-red spectroscopy tissue oximeter measures the changes of absorber concentrations (such as oxy-hemoglobin, deoxy-hemoglobin, cytochrome aa3). This is made possible by recording the optical density change under different physiological status. This paper describes the average penetration depth, average photon path-length and spatial sensitive profile in multi-layered tissue model using Monte-Carlo method. The result shows the probe geometry of the sensor, which is the separation between the light source and the detector, has a great influence on the sensitivity of measurement. Increasing this separation properly allows the improvement of the sensitivity of measurement and the increase of the probability of looking at oxygenation deep under the surface tissue. But this improvement is limited by the decrease of signal-noise ratio. Optimum probe spacing should be estimated for special tissue structure.
基于散射介质下的修正朗伯-比尔定律，近红外光谱组织血氧仪可测量吸收体浓度（如氧合血红蛋白、脱氧血红蛋白、细胞色素aa3）的变化。通过记录不同生理状态下的光密度变化来实现这一点。本文使用蒙特卡洛方法描述了多层组织模型中的平均穿透深度、平均光子路径长度和空间敏感分布。结果表明，传感器的探头几何结构，即光源与探测器之间的间距，对测量灵敏度有很大影响。适当增加此间距可提高测量灵敏度，并增加观察表面组织下方深处氧合情况的概率。但这种提高受到信噪比降低的限制。应针对特殊组织结构估计最佳探头间距。
