Verkruysse Wim, Zhang Rong, Choi Bernard, Lucassen Gerald, Svaasand Lars O, Nelson J Stuart
Beckman Laser Institute, University of California, Irvine, CA 92612, USA.
Phys Med Biol. 2005 Jan 7;50(1):57-70. doi: 10.1088/0031-9155/50/1/005.
The diffuse reflectance spectrum of human skin in the visible region (400-800 nm) contains information on the concentrations of chromophores such as melanin and haemoglobin. This information may be extracted by fitting the reflectance spectrum with an optical diffusion based analytical expression applied to a layered skin model. With the use of the analytical expression, it is assumed that light transport is dominated by scattering. For port wine stain (PWS) and highly pigmented human skin, however, this assumption may not be valid resulting in a potentially large error in visual reflectance spectroscopy (VRS). Monte Carlo based techniques can overcome this problem but are currently too computationally intensive to be combined with previously used fitting procedures. The fitting procedure presented herein is based on a library search which enables the use of accurate reflectance spectra based on forward Monte Carlo simulations or diffusion theory. This allows for accurate VRS to characterize chromophore concentrations in PWS and highly pigmented human skin. The method is demonstrated using both simulated and measured reflectance spectra. An additional advantage of the method is that the fitting procedure is very fast.
人体皮肤在可见光区域（400 - 800纳米）的漫反射光谱包含了诸如黑色素和血红蛋白等发色团浓度的信息。这些信息可以通过将反射光谱与应用于分层皮肤模型的基于光扩散的解析表达式进行拟合来提取。使用该解析表达式时，假定光传输以散射为主。然而，对于葡萄酒色斑（PWS）和色素沉着严重的人体皮肤，这一假设可能不成立，从而导致视觉反射光谱法（VRS）中可能出现较大误差。基于蒙特卡罗的技术可以克服这个问题，但目前计算量太大，无法与先前使用的拟合程序相结合。本文提出的拟合程序基于库搜索，它能够使用基于正向蒙特卡罗模拟或扩散理论的精确反射光谱。这使得准确的VRS能够用于表征PWS和色素沉着严重的人体皮肤中的发色团浓度。该方法通过模拟和实测反射光谱进行了验证。该方法的另一个优点是拟合程序非常快速。
