Assembly, calibration and application of a hyperspectral image system for biomedical imaging

Abstract

The use of light-mater interaction for the detection of chemical-physical processes is not a new concept in biology, though it is not fully developed for tissue diagnosis. It is already known that reflectance as well as fluorescence images can provide important information on biochemical composition and metabolic processes in biological samples. In spite of this potential, the experimental available image systems usually are complex making clinical implementation difficult. In this study, we describe the construction and characterization of an experimental device to produce hyperspectral images between 400 and 1.000 nm. The system is composed by a spectrograph, a set of lenses for image formation and a CCD camera for acquisition. We describe in details also the calibration procedure to determine system parameters as image width, field of vision, spectral and space resolution. The illumination system uses high power light emitting diodes, either at white light or centered at 470 and 405 nm. We demonstrate that our system is able to obtain reflectance as well as fluorescence images of biological samples. As example of application it was used in Dentistry. Data from spectral images of violetinduced autofluorescence of bovine tooth were evaluated in order to detect demineralization process. Our results demonstrate that this system is operating as projected and it has enough sensitivity to detect changes in low-intensity optical signals as fluorescence. © 2009 Springer-Verlag.