Photo caption:The colorized photos above show two images of pigskin taken under different lighting conditions (top and middle) that were combined by NIST and Johns Hopkins researchers to reveal greater subsurface detail (bottom).
Light scattering method reveals details under skin
A new optical method that can image subsurface structures under skin has been demonstrated by scientists at the National Institute of Standards and Technology (NIST) and the Johns Hopkins University Applied Physics Laboratory.
The method relies on differences in the way surface and subsurface features of various materials scatter light. It was demonstrated with small pieces of pigskin and inorganic materials but might eventually prove useful for imaging living tissues to help diagnose or determine the extent of various types of skin cancers. A paper on the work was presented at a recent technical meeting and is in press.*
The imaging process involves illuminating a sample with polarized light, which has its electric field oriented in a particular direction, and using a digital camera with a rotating polarization filter to image the light scattered from the sample. Researchers manipulated the polarization to minimize light scattered from the rough skin surface, and positioned the light source in multiple locations to separate out, and delete, light scattered more than one time from deeper sample layers. By using certain polarization settings and combining two images made with the light source in different positions, they generated a processed image that reveals significant subsurface structure.
Polarized light imaging already is used in dermatology to identify the edges of lesions. The new method minimizes the effects of two types of unwanted light scattering at once, and thus, if confirmed by other methods, might someday be used in a clinical setting to produce more detailed images of deeper layers of skin.
The method was developed under a Cooperative Research and Development Agreement between the two institutions. The project adapted light scattering techniques originally developed by NIST researchers to image surface and subsurface features in inorganic materials such as silicon wafers, mirrors and paint coatings. Scientists currently are working on making the new method easier and faster to use.
J.C. Ramella-Roman, D. Duncan, T.A. Germer. 2005. Out-of-plane polarimetric imaging of skin: Surface and subsurface effects. In Photonic Therapeutics and Diagnostics, Nikiforos Kollias et al., eds. Proc. SPIE 5686 (forthcoming).
Eurekalert网4月12日报道，来自美国国家标准和技术研究所（NIST）和约翰·霍普金斯大学应用物理学实验室的科学家们展示了一种可以用来观察皮肤表面下结构的新光学扫描技术。
该方法基于多种物质散射光表面和表面下特性的不同，已经在小片的猪皮和无机材料中得到证实，而且最终可能用于生物体组织来帮助诊断各种皮肤癌的程度。关于该项研究的论文已经呈现在最近的一次技术会议上。
整个过程包括：用规定电场方向的偏振光（polarized light）照亮样本，然后使用具有旋转偏振滤色盘的数码相机拍下样本散射出来的光。研究人员对偏振进行控制，使粗糙皮肤表面散射出来的光减到最小。接着在多个方位定位光源，进行分离和去除。他们通过使用某种偏振装置，将两个不同方向光源的图像合并在一起，从而产生出一种可以揭示皮肤表面下结构的图像。
偏振光成像早已应用在皮肤医学中，用来确定病情的程度。新方法将两种不需要的由光散射带来的影响减到最小，如果得到其他方法的证实，那么这项研究可能会被用于临床对深层皮肤的研究。
这项研究采用了由NIST研究人员开发的光散射技术，对无机材料的表层和表层下特性进行成像。目前，科学家正在研究更简单、更快速的新方法。
