High speed spectral domain optical coherence tomography for retinal imaging at 500,000 A‑lines per second.
High speed spectral domain optical coherence tomography for retinal imaging at 500,000 A‑lines per second.
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DOI：
10.1364/boe.2.002770
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发表时间：
2011-10-01
影响因子：
3.4
通讯作者：
Wang R
中科院分区：
文献类型：
--
作者：
An L;Li P;Shen TT;Wang R
介绍了一种用于中心波长为850 nm的超高速光谱域光学相干层析成像(SDOCT)的新发展，它采用了两个高速的线扫描CMOS摄像机，每个摄像机的工作频率为250 kHz。通过精确控制两台相机的记录和读取时间周期，SDOCT系统实现了每秒50万A线的成像速度，同时保持了高轴向分辨率(~8μm)和可接受的深度测距(~2.5 mm)。利用该系统，我们提出了两种用于人体视网膜成像的扫描方案。第一个目标是实现各向同性的密集采样和快速扫描速度，能够在0.72秒内对覆盖4x4平方毫米的区域进行3D成像。在这种情况下，B帧速率是700赫兹，各向同性密集采样是沿着快轴和慢轴的500条A线。该扫描协议最大限度地减少了运动伪影，从而使执行双向平均成为可能，从而提高了系统的信噪比，同时最小化了其分辨率的降低。第二种方案被设计成在大视野内扫描视网膜，其中沿着快轴和慢轴捕获1200条A线，覆盖10平方毫米，以提供关于视网膜状态的整体信息。由于成像时间相对较长(3D扫描需要4秒)，运动伪影是不可避免的，这使得对3D数据集的解释变得困难，特别是在深度分辨的内面部眼底图像中。为了缓解这一困难，我们建议使用相对高反射的视网膜色素上皮层作为参考，沿着快轴和慢轴平坦化原始3D数据集。我们表明，所提出的系统为人类视网膜成像提供了卓越的性能。
We present a new development of ultrahigh speed spectral domain optical coherence tomography (SDOCT) for human retinal imaging at 850 nm central wavelength by employing two high-speed line scan CMOS cameras, each running at 250 kHz. Through precisely controlling the recording and reading time periods of the two cameras, the SDOCT system realizes an imaging speed at 500,000 A-lines per second, while maintaining both high axial resolution (~8 μm) and acceptable depth ranging (~2.5 mm). With this system, we propose two scanning protocols for human retinal imaging. The first is aimed to achieve isotropic dense sampling and fast scanning speed, enabling a 3D imaging within 0.72 sec for a region covering 4x4 mm2. In this case, the B-frame rate is 700 Hz and the isotropic dense sampling is 500 A-lines along both the fast and slow axes. This scanning protocol minimizes the motion artifacts, thus making it possible to perform two directional averaging so that the signal to noise ratio of the system is enhanced while the degradation of its resolution is minimized. The second protocol is designed to scan the retina in a large field of view, in which 1200 A-lines are captured along both the fast and slow axes, covering 10 mm2, to provide overall information about the retinal status. Because of relatively long imaging time (4 seconds for a 3D scan), the motion artifact is inevitable, making it difficult to interpret the 3D data set, particularly in a way of depth-resolved en-face fundus images. To mitigate this difficulty, we propose to use the relatively high reflecting retinal pigmented epithelium layer as the reference to flatten the original 3D data set along both the fast and slow axes. We show that the proposed system delivers superb performance for human retina imaging.