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三个宽波段的形式提供有限的可见光光谱：红、绿和蓝。多光谱图像记录了许多狭窄的光谱波段，可以提供观察或传统摄影无法提供的信息。特别是，先进的计算技术可以用来以完全非侵入性的方式得出类似活组织检查的定量地图，以表征组织成分。通过优化技术，可以选择不同的谱带集合，以可视化不同的组织成分，例如氧化和非氧化的血液、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被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，因此可能在一系列图像中移位。虽然可以使用图像处理技术(图像配准)来校正位移，但点的照度在移动时也会发生变化，这不能通过配准来校正。因此，有必要在比组织的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(例如，白光)光源和数字摄像机，有各种各样的商业数字成像系统可用。在需要有限光谱带宽的地方，可以插入窄滤光片。然而，这样的系统可能不允许以足以用于非静止物体的速度获取不同光谱波段的一系列图像。该项目的主要目标是开发一种可用于一系列成像仪器的模块化成像系统，使它们能够以视频速度帧速率顺序获取任意波长的数字图像。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，通过计算机控制接口连接，从而使照明和图像捕获同步，并可根据应用的需要选择采集的顺序和时间。设计将通过建立和演示与眼底相机一起使用的原型系统来举例，以用于视网膜的快速多光谱成像。最近的研究表明，从这类图像数据中提取的视网膜血液定量图可能会取代侵入性荧光血管造影术，后者通常用于揭示视网膜出血，这是糖尿病视网膜病变的早期迹象，可能导致失明。显示黄斑色素数量和分布的类似地图可以用来预测老年性黄斑变性(ARMD)发展成威胁视力的并发症的风险。除了改进多光谱视网膜成像，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，包括对活细胞动态过程的荧光显微镜研究。设想的其他应用包括将成像仪与内窥镜和光学断层成像系统等诊断成像系统一起使用，以实现对人体组织和器官的非侵入性体内诊断和监测。

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.