摘要
针对光学相干断层成像(OCT)系统在发散扫描模式下图像失真的问题,本文研究了图像产生畸变的机理,对图像的畸变量进行了定量分析,提出了一种发散扫描模式OCT图像矫正与重构算法。首先,基于最大类间方差法对原始图像进行了降噪与增强预处理,以减少背景噪声对图像重构的影响。然后,建立OCT原始图像和重构图像的映射关系,从而实现对畸变图像的矫正。利用OCT系统对玻璃样品在发散扫描模式下进行成像,对图像进行矫正后测量样品厚度和宽度并与实际值对比,厚度测量误差为-0.012~0.053 mm,宽度测量误差为-0.107~0.045 mm。以离体猪眼为样品,对比平行扫描模式和发散扫描模式的测量结果,角膜厚度测量误差为-0.022~0.014 mm,虹膜间距测量误差为-0.121~-0.015 mm。实验验证了该算法在抑制OCT图像背景噪声的同时,能够有效矫正图像畸变,对于发散扫描模式OCT图像在医疗诊断和手术导航领域的应用具重要意义。
In order to solve the problem of image distortion in sector scan mode by optical coherence tomography(OCT),this study investigates the causes,provides a quantitative analysis,and proposes a rectification and reconstruction algorithm for the OCT images in sector scan mode. First,based on the maximization of interclass variance(OTSU)algorithm,a preprocessing of denoise and enhancement was applied to the original image,thereby facilitating the reduction of the influence of background noise on image reconstruction. Thereafter,a mapping relationship between the original OCT image and the reconstructed image was established,thus,achieving the rectification of the distorted OCT image. Here,we took advantage of the OCT system to make a glass sample from the images in sector scan mode and measured the thickness and width of the glass sample after rectifying the images. On comparing the measured values with the actual ones,we found that the measured thickness error ranges between-0. 012 mm and 0. 053 mm,and the measured width error ranges from-0. 107 mm to 0. 045 mm. Furthermore,taking the eyes of pigs in vitro as the sample,we made a comparison between the measurement results in the rectangular scan mode to that in the sector scan mode and found that the measured thickness error of corneas range between-0. 022 mm and 0. 014 mm,and the measured width error of irises range from-0. 121 mm to-0. 015 mm. Thus,the proposed method reduces the background noise of OCT images and corrects the image distortion effectively. This is of great significance for the application of OCT in sector scan mode,especially,in the field of medical diagnosis and surgical navigation.
作者
杨帆
刘连圣
翟祚盼
范立成
YANG Fan;LIU Lian-sheng;ZHAI Zuo-pan;FAN Li-cheng(School of Mechanical and Electrical Engineering,Soochow University,Suzhou 215000,Jiangsu,China)
出处
《光学精密工程》
EI
CAS
CSCD
北大核心
2021年第8期1968-1975,共8页
Optics and Precision Engineering
基金
国家自然科学基金(No.61475108)。
关键词
光学相干断层成像
发散扫描
图像畸变
图像重构
最大类间方差法
OCT
sector scan mode
image distortion
image reconstruction
the maximization of interclass variance algorithm
