Discrimination of gallbladder stone employing Laser-Induced Breakdown Spectroscopy (LIBS) and Photoacoustic Spectroscopy (PAS)

Abstract

Compositional analysis of gallstone samples has been carried out, using Laser-Induced Breakdown Spectroscopy (LIBS) and Photoacoustic Spectroscopy (PAS). Classification of gallstone has been made on the basis of intensities of the inorganic and organic constituents present in the LIBS spectra. A regression plot is drawn between LIBS spectral intensities of organic & inorganic elements and the stoichiometric ratio of Cholesterol, Bilirubin and Calcium Carbonate. Atomic lines of various elements, as well as molecular signatures of CaO Orange band, CN Violet band, and C₂ Swan band, are observed in LIBS spectra. The relative hardness of gallstones is estimated from the intensity ratio of ionic to neutral atomic lines of the species observed in LIBS spectra. PAS is used for detecting molecular constituents in the gallstones. Principal Component Analysis (PCA) is performed for the discrimination of gallstones. It is found that PAS data, in combination with LIBS provide a suitable method for the compositional analysis of gallstones.

Keywords: Gallstone; LIBS; PAS; PCA.