Spectral distortion in diffuse molecular luminescence tomography in turbid media

Research output: Contribution to journalArticle

Authors

Colleges, School and Institutes

Abstract

The influence of tissue optical properties on the shape of near-infrared (NIR) fluorescence emission spectra propagating through multiple centimeters of tissue-like media was investigated. Fluorescence emission spectra measured from 6 cm homogeneous tissue-simulating phantoms show dramatic spectral distortion which results in emission peak shifts of up to 60 nm in wavelength. Measured spectral shapes are highly dependent on the photon path length and the scattered photon field in the NIR amplifies the wavelength-dependent absorption of the fluorescence spectra. Simulations of the peak propagation using diffusion modeling describe the experimental observations and confirm the path length dependence of fluorescence emission spectra. Spectral changes are largest for long path length measurements and thus will be most important in human tomography studies in the NIR. Spectrally resolved detection strategies are required to detect and interpret these effects which may otherwise produce erroneous intensity measurements. This observed phenomenon is analogous to beam hardening in x-ray tomography, which can lead to image artifacts without appropriate compensation. The peak shift toward longer wavelengths, and therefore lower energy photons, observed for NIR luminescent signals propagating through tissue may readily be described as a beam softening phenomenon.

Details

Original languageEnglish
Pages (from-to)102024
Number of pages1
JournalJournal of Applied Physics
Volume105
Issue number10
Publication statusPublished - 19 May 2009

Keywords

  • spectral line breadth, fluorescence, spectral line shift, turbidity, molecular biophysics, phantoms, biological tissues, infrared spectra