<title>Gallstone identification by fluorescence spectroscopy</title>

Abstract

Gallstones have been classified as being cholesterol type and pigment type. The classification is important for diet control of the patient to avoid recurrence of the stone. Spectroscopy is a sensitive technique to determine the composition of the gallstone both in-vitro and in-vivo. this work deals with the fluorescence spectroscopy of gallstone. For fluorescence spectroscopic studies of gallstone, samples were excited with 5 mw of 488 nm line of argon-ion laser and spectra were recorded with a SPEX 1877E triplemate attached with a cooled PMT and DM3000R data acquisition system. Fluorescence spectra from pure cholesterol and bilirubin were also recorded for comparison. Different types of gallstones: mixed, cholesterol, pigment type were studied. All spectra exhibited a very broad band, 500 to 800 nm and sometimes two bands, depending on type of stone. Pure cholesterol shows three prominent fluorescence peaks at 513, 550, 583 nm along with two peaks at approximately 568 and 586 nm. Pure bilirubin shows prominent peak at 628 nm, without any Raman line. From fluorescence spectra different types of stones are identified. Different gallstones studied show a mixture of cholesterol and bilirubin types and the ratio of the two varies from one sample type to another.