University of Connecticut, Department of Electrical and Computer Engineering, 371 Fairfield Road, Storrs, Connecticut 06269, USA.
J Biomed Opt. 2010 May-Jun;15(3):036003. doi: 10.1117/1.3431086.
When a large, highly absorbing breast lesion is imaged by optical tomography in reflection geometry, most of the photons are absorbed by the top portion of the lesion. As a result, the lower portion of the lesion is not quantified correctly. This posterior light shadowing effect is similar to the sound shadowing effect frequently seen in pulse-echo ultrasound images. The presence of significant posterior shadowing of a lesion in ultrasound images suggests malignance. The light shadowing effect due to optical contrast is characterized using a simple measure and validated by the Monte Carlo photon-tracking method and phantom experiments. Clinical examples of large malignant and benign lesions are presented to demonstrate the shadowing effect and the utility of the measure. Understanding and quantifying the shadowing effect due to optical contrast is important for characterizing larger malignant cancers from benign lesions.
当大而高吸收率的乳房病变在反射几何结构下用光学层析成像技术进行成像时，大部分光子会被病变的上半部分吸收。结果，病变的下半部分无法被正确量化。这种后向光遮蔽效应类似于在脉冲回波超声图像中经常见到的声影效应。超声图像中病变的显著后向阴影提示恶性病变的存在。利用一种简单的方法对光对比度引起的光遮蔽效应进行了特征描述，并通过蒙特卡罗光子跟踪法和体模实验进行了验证。文中还给出了大的恶性和良性病变的临床实例，以演示遮蔽效应和该测量方法的应用。理解和量化光对比度引起的遮蔽效应对于将较大的恶性肿瘤与良性病变区分开来非常重要。
