MEDICAL DIAGNOSTIC SYSTEM BASED ON SIMULTANEOUS MULTISPECTRAL FLUORESCENCE IMAGING

A multicolor fluorescence imaging system applied to medical diagnostic s is described. The system presented simultaneously records four fluor escence images in different wavelength bands, permitting low-resolutio n spectroscopy imaging. An arithmetic function image of the four spect ral images is constructed by a pixel-to-pixel calculation and is prese nted on a monitor in false-color coding. A sensitive detector is requi red for minimizing the excitation energy necessary to obtain an image and thus avoid side effects on the investigated tissue. Characteristic s of the system of importance for the detector sensitivity as well as image quality are discussed. A high degree of suppression of ambient b ackground light is reached with this system by the use of a pulsed las er as an excitation source together with gated detection. Examples of fluorescence images from tumors on the hind legs and in the brain of r ats injected with Photofrin are given.