University of Toronto, Department of Medical Biophysics, Temerty Faculty of Medicine, Toronto, Ontario, Canada.
University Health Network, Princess Margaret Cancer Centre, Toronto, Ontario, Canada.
J Biomed Opt. 2023 Oct;28(10):102906. doi: 10.1117/1.JBO.28.10.102906. Epub 2023 Sep 9.
Early tooth demineralization may be detectable through spatial analysis of polarized light images as demonstrated in this study. This may also prove useful in the early detection of epithelial tumors that comprise the majority of the cancer burden worldwide.
The spatial properties of polarized light images have not been greatly exploited in biomedicine to improve sensitivity to superficial tissue regions; therefore, we investigate the optical sampling depth effects as a function of location in the backscattered polarimetric images.
Backscattered linear polarization intensity distributions exhibit four-lobed patterns arising through single-scattering, multiple-scattering, and geometrical effects. These photon pathway dynamics are investigated through experimental imaging of microsphere suspensions along with corroborative computational polarization-sensitive Monte Carlo modeling. The studied sampling depth effects of linear and circular polarization images (explored in a previous study) are then evaluated on normal and demineralized human teeth, which are known to differ in their surface and sub-surface structures.
Backscattered linear polarization images exhibit enhanced sensitivity to near-surface properties of media (for example, surface roughness and turbidity) at specific locations within the four-lobed patterns. This yields improved differentiation of two tooth types when spatially selecting image regions in the direction perpendicular to the incident linear polarization vector. Circular polarimetric imaging also yields improved differentiation through spatial selection of regions close to the site of illumination. Improved sensitivity to superficial tissues is achieved through a combination of these linear and circular polarimetric imaging approaches.
Heightened sampling sensitivity to tissue microstructure in the surface/near-surface region of turbid tissue-like media and dental tissue is achieved through a judicious spatial selection of specific regions in the resultant co-linear and cross-circular backscattered polarimetric images.
本研究表明，早期牙齿脱矿可以通过偏光图像的空间分析来检测。这对于早期发现构成全球癌症负担的大部分上皮肿瘤也可能证明是有用的。
偏光图像的空间特性在生物医学中尚未得到广泛利用，以提高对浅表组织区域的敏感性；因此，我们研究了作为反向散射偏光图像中位置函数的光学采样深度效应。
反向散射线性偏振光强度分布呈现出四叶图案，这是通过单次散射、多次散射和几何效应产生的。通过微球悬浮液的实验成像以及与验证计算偏振敏感蒙特卡罗建模，研究了这些光子路径动力学。然后，在正常和脱矿化的人牙齿上评估了线性和圆偏振图像的研究采样深度效应（在之前的研究中进行了探讨），这些牙齿在其表面和亚表面结构上已知有所不同。
反向散射线性偏振图像在四叶图案的特定位置上对介质的近表面特性（例如表面粗糙度和浑浊度）具有更高的敏感性。这在垂直于入射线性偏振矢量的方向上空间选择图像区域时，产生了对两种牙齿类型的更好区分。通过空间选择接近照明位置的区域，圆偏振成像也可以实现更好的区分。通过这些线性和圆偏振成像方法的组合，可以实现对浅表组织的更高敏感性。
通过明智地选择反向散射共线和交叉圆偏振图像中特定区域，可以实现混浊组织样介质和牙齿的表面/近表面区域组织微观结构的采样敏感性提高。
