Modular discrete-wavelength light source synchronised with an intensity imaging camera for high-speed multispectral imaging

颜色在许多疾病的临床诊断中起着重要作用。然而，眼睛中的感受器以及标准彩色相机中的传感器只能以红、绿、蓝三种宽频带的形式提供有限的可见光谱。多光谱图像记录了许多狭窄的光谱带，可以产生通过观察或传统摄影所无法获得的信息。特别是，先进的计算技术可用于以完全无创的方式获得组织组成特征的活检样定量图。通过优化技术，可以选择不同的光谱波段，以可视化不同的组织成分，如氧化和非氧化血液、黑色素、黄斑色素、细胞和细胞器的密度等。这些技术在组织可以固定的情况下工作得很好，但在某些应用中（例如视网膜成像，内窥镜检查），被检查的组织受到不自主运动的影响，因此在一系列图像中可能会发生移位。虽然位移可以使用图像处理技术（图像配准）来纠正，但点的照明也会随着运动而变化，这不能通过配准来纠正。因此，有必要在比组织自然运动更快的时间尺度上获得图像，同时确保足够长的曝光时间以保持高图像质量。基于宽带（如白光）光源和数字摄像机的商业数字成像系统种类繁多。在需要有限频谱带宽的地方，可以插入窄滤光片。然而，这样的系统可能不允许以足够的速度获取非静止物体的不同光谱带的一系列图像。该项目的主要目标是开发一种模块化成像系统，该系统可用于一系列成像仪器，使它们能够以视频速度帧速率连续获取任意数量波长的数字图像。该系统将包括一个与科学级单色成像相机同步的离散多光谱光源，通过计算机控制的接口连接，使照明和图像捕获同步，并且可以根据应用程序的需要选择采集的顺序和时间。该设计将通过构建和演示一个用于眼底相机的原型系统来实现视网膜的快速多光谱成像。最近的研究表明，从这些图像数据中获得的视网膜血液定量图可以替代侵入性荧光素血管造影，后者通常用于显示视网膜出血，这是糖尿病视网膜病变的早期征兆，可能导致失明。显示黄斑色素数量和分布的类似图谱可用于预测年龄相关性黄斑变性（ARMD）中发生威胁视力的并发症的风险。所提出的成像仪是一种具有潜在广泛适用性的通用设备。除了改进多光谱视网膜成像外，该项目还将展示成像仪作为一种灵活的研究设备的价值，用于生物科学的探索性研究，包括荧光显微镜对活细胞动态过程的研究。设想的其他应用包括将成像仪与诊断成像系统一起使用，例如内窥镜和光学断层扫描系统，用于非侵入性体内诊断和监测人体组织和器官。

Colour plays an important role in the clinical diagnosis of many conditions. However, the receptors in the eye, as well as the sensors in a standard colour camera, provide only a limited representation of the visible spectrum in the form of three broad bands: red, green and blue. Multispectral images, where many narrow spectral bands are recorded, can yield information beyond what is possible by observation or conventional photography. In particular, advanced computational techniques can be used to derive biopsy-like quantitative maps characterising tissue composition in a totally non-invasive manner. Different sets of spectral bands can be selected, through optimisation techniques, to visualise different tissue components such as oxidised and non-oxidised blood, melanin, macular pigment, density of cells and organelles, etc. These techniques work well in situations where the tissue can be immobilised, but in some applications (e.g. retinal imaging, endoscopy), the tissue under examination is subject to involuntary movement and so can become displaced in a sequence of images. Whilst the displacement can be corrected using image processing techniques (image registration), the illumination of points also changes under movement, and this cannot be corrected by registration. It is thus necessary to obtain images at timescales faster than the natural movement of the tissue, at the same ensuring sufficiently long exposure times to maintain high image quality.A wide variety of commercial digital imaging systems are available based on broadband (e.g. white light) sources and digital video cameras. Where limited spectral bandwidth is required, narrow optical filters can be inserted. However, such systems may not allow a series of images at different spectral bands to be acquired with the speed sufficient for non-stationary objects. The principal objective of this project is to develop a modular imaging system which can be used in a range of imaging instruments to enable them to sequentially acquire digital images at an arbitrary number of wavelengths at video speed frame rates. The system will comprise a discrete multispectral light source synchronised with a scientific-grade monochrome imaging camera, connected via a computer controlled interface so that illumination and image capture are synchronised and the sequence and timing of the acquisition can be selected according to the needs of the application.The design will be exemplified by building and demonstrating a prototype system for use with a fundus camera for rapid multispectral imaging of the retina. Recent research has shown that quantitative maps of retinal blood derived from such image data may provide a substitute for invasive fluorescein angiography, commonly used to reveal retinal haemorrhages which are an early sign of diabetic retinopathy and may lead to blindness. Similar maps showing the quantity and distribution of Macular Pigment could be used to predict the risk of developing sight-threatening complications in age-related macular degeneration (ARMD). The proposed imager is a generic device with potentially broad applicability. As well as improving multispectral retinal imaging, the project will demonstrate the value of the imager as a flexible research device for exploratory studies in biosciences involving fluorescence microscopy studies of dynamic processes in living cells. Other applications envisaged include the use of the imager with diagnostic imaging systems such as endoscopes and optical tomography systems for non-invasive in-vivo diagnosis and monitoring of human tissues and organs.