谱域光学相干层析系统中基于解卷积方法的像质优化

谱域光学相干层析（spectral domain optical coherence tomography, 简记为SD-OCT）系统的轴向点扩散函数（point spread function, 简记为PSF）并不具备空不变特性，无法直接应用于解卷积运算.为实现SD-OCT系统成像质量基于解卷积算法的优化，本文采用数值校正后的轴向扫描信号和轴向有效PSF来实施基于Lucy-Richardson算法的解卷积运算，进而实现了SD-OCT系统中图像质量尤其是轴向分辨率的改善.本文理论分析了SD-OCT系统中导致轴向有效PSF随成像深度增大而下降和图像模糊的因素，阐述了利用解卷积算法实现图像质量优化的过程，基于建立的SD-OCT系统实施了不同成像深度位置处PSF的标定，并利用离散轴向位置处PSF的峰值拟合了轴向有效PSF的调制函数.利用调制函数对所有轴向扫描信号进行数值校正，然后根据轴向有效PSF进行解卷积算法.典型样品的解卷积图像重建结果表明，提出的解卷积方法能有效提高系统的轴向分辨率，同时有效抑制系统灵敏度随成像深度增大而下降的趋势. 关键词： 谱域光学相干层析 Lucy-Richardson解卷积 有效点扩散函数

Imaging quality enhancement by deconvolution in spectral domain optical coherence tomography

Deconvolution methods are not feasible in spectral domain optical coherence tomography (SD-OCT) system due to the linear space variant property of its axial point spread function (PSF). In order to improve the axial resolution and enhance the imaging quality of the SD-OCT system, a Lucy-Richardson algorithm based deconvolution method is implemented with the numerically compensated A-scan signals and the effective axial PSF in this paper. The main factors decreasing the value of PSF along the axial direction and blurring the images, as well as the deconvolution process, are theoretical studied. With the developed SD-OCT system, the axial modulation function of the PSF is retrieved by curve fitting of the measured peak values of the PSF at different axial positions. After compensating the A-scan signal with the modulation function, deconvolution is performed with the measured effective axial PSF. In vivo imaging on typical samples is conducted and reconstruction is done based on the deconvolution method. The comparing results demonstrate that the proposed deconvolution method not only enhances the axial resolution but also improves the depth dependent sensitivity fall-off in SD-OCT system.