Quantitative Raman spectroscopy in turbid media

• Published in: Journal of Biomedical Optics Vol. 15; no. 3; p. 037016
• Main Authors: Reble, Carina, Gersonde, Ingo H, Andree, Stefan, Eichler, Hans-Joachim, Helfmann, Jrgen
• Format: Journal Article
• Language: English
• Published: United States 01.05.2010
• Subjects: Computer Simulation; Diffusion; Distortion; Elasticity; Impact tests; Monte Carlo Method; Monte Carlo methods; Phantoms, Imaging; Raman scattering; Reflectance; Reflectivity; Signal Processing, Computer-Assisted; Silicones - chemistry; Spectrum Analysis, Raman - methods
• ISSN: 1083-3668; 1560-2281
• DOI: 10.1117/1.3456370

Intrinsic Raman spectra of biological tissue are distorted by the influences of tissue absorption and scattering, which significantly challenge signal quantification. A combined Raman and spatially resolved reflectance setup is introduced to measure the absorption coefficient a and the reduced scattering coefficient of the tissue, together with the Raman signals. The influence of a and on the resonance Raman signal of -carotene is measured at 1524 cm−1 by tissue phantom measurements and Monte Carlo simulations for a=0.01 to 10 mm−1 and =0.1 to 10 mm−1. Both methods show that the Raman signal drops roughly proportional to 1/ a for a>0.2 mm−1 in the measurement geometry and that the influence of is weaker, but not negligible. Possible correction functions dependent on the elastic diffuse reflectance are investigated to correct the Raman signal for the influence of a and , provided that a and are measured as well. A correction function based on the Monte Carlo simulation of Raman signals is suggested as an alternative. Both approaches strongly reduce the turbidity-induced variation of the Raman signals and allow absolute Raman scattering coefficients to be determined.