Spectroscopic imaging and the characterization of the autofluorescence properties of human bronchus tissues using UV laser diodes

Ultraviolet laser diodes (UV-LD) were used for the excitation source of the autofluorescence (AF) measurements and spectroscopic imaging of the AF originated from the human bronchus was obtained. The AF spectra from the normal bronchus tissues were measured and the clear AF spectrum was obtained by using a short wavelength (400 nm) laser diode; the overlap of the AF signal and excitation source could be substantially eliminated. In order to study the origin of the AF intensity deterioration from the bronchus tissue due to the formation of the tumor tissues, the fluorescence spectrum was measured for various AF substances under various conditions. The blue AF signal of the elastin and NADH solutions which could not be easily studied by the conventional excitation light sources as well as the green AF became weak by adding the lactic acid. The AF spectrum was measured for 512 × 512 pixels and the intensity mapping as a function of the emission wavelength was obtained. Two-dimensional information of the AF signal intensity distribution for a certain wavelength component was measured. The feature originated from the region as small as about 100 μm could be recognized. The numerical calculation of the data was performed and the precise feature of the AF was revealed.