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Journal of Biomedical Optics • Open Access

Near-infrared light penetration profile in the rodent brain
Author(s): Ammar Abdo; Ali Ersen; Mesut Sahin

Paper Abstract

Near-infrared (NIR) lasers find applications in neuro-medicine both for diagnostic and treatment purposes. Penetration depth and profile into neural tissue are critical parameters to be considered in these applications. Published data on the optical properties of rodent neural tissue are rare, despite the frequent use of rats as an animal model. The aim of this study was to measure the light intensity profile inside the rat brain using a direct method, while the medium is being illuminated by an NIR laser beam, and compare the results with in vitro measurements of transmittance in the rat brain slices. The intensity profile along the vertical axis had an exponential decline with multiple regions that could be approximated with different coefficients. The Monte Carlo method that was used to simulate light–tissue interactions and predict the scattering coefficient of brain tissue from the measurements suggested that more scattering occurred in deeper layers of the cortex. A single scattering coefficient of 125  cm −1 was estimated for cortical layers from 300 to 1500 μm and a gradually increasing value from 125 to 370  cm −1 for depths of 1500 to 3000 μm. The deviations of in vivo results from the in vitro transmittance measurements, as well as the postmortem in vivo results from the alive measurements were significant.

Paper Details

Date Published: 5 July 2013
PDF: 7 pages
J. Biomed. Opt. 18(7) 075001 doi: 10.1117/1.JBO.18.7.075001
Published in: Journal of Biomedical Optics Volume 18, Issue 7
Show Author Affiliations
Ammar Abdo, New Jersey Institute of Technology (United States)
Ali Ersen, New Jersey Institute of Technology (United States)
Mesut Sahin, New Jersey Institute of Technology (United States)

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