Comparison of finite-difference transport and diffusion calculations for photon migration in homogeneous and heterogeneous tissues

Andreas H. Hielscher, Raymond E. Alcouffe, Randall L. Barbour

    Research output: Contribution to journalArticlepeer-review

    Abstract

    We analyse the limits of the diffusion approximation to the time- independent equation of radiative transfer for homogeneous and heterogeneous biological media. Analytical calculations and finite-difference simulations based on diffusion theory are compared with discrete-ordinate, finite- difference transport calculations. The influence of the ratio of absorption and transport scattering coefficient (μ(a)/μ'(s)) on the accuracy of the diffusion approximation are quantified and different definitions for the diffusion coefficient, D, are discussed. We also address effects caused by void-like heterogeneities in which absorption and scattering are very small compared with the surrounding medium. Based on results for simple homogeneous and heterogeneous systems, we analyse diffusion and transport calculation of light propagation in the human brain. For these simulations we convert density maps obtained from magnetic resonance imaging (MRI) to optical- parameter maps (μ(a) and μ'(s)) of the brain. We show that diffusion theory fails to describe accurately light propagation in highly absorbing regions, such as haematoma, and void-like spaces, such as the ventricles and the subarachnoid space.

    Original languageEnglish (US)
    Pages (from-to)1285-1302
    Number of pages18
    JournalPhysics in Medicine and Biology
    Volume43
    Issue number5
    DOIs
    StatePublished - May 1998

    ASJC Scopus subject areas

    • Radiological and Ultrasound Technology
    • Radiology Nuclear Medicine and imaging

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