Implementation of the equation of radiative transfer on block-structured grids for modeling light propagation in tissue

Ludguier D. Montejo, Alexander D. Klose, Andreas H. Hielscher

    Research output: Contribution to journalArticlepeer-review

    Abstract

    We present the first algorithm for solving the equation of radiative transfer (ERT) in the frequency domain (FD) on three-dimensional block-structured Cartesian grids (BSG). This algorithm allows for accurate modeling of light propagation in media of arbitrary shape with air-tissue refractive index mismatch at the boundary at increased speed compared to currently available structured grid algorithms. To accurately model arbitrarily shaped geometries the algorithm generates BSGs that are finely discretized only near physical boundaries and therefore less dense than fine grids. We discretize the FD-ERT using a combination of the upwind-step method and the discrete ordinates (SN) approximation. The source iteration technique is used to obtain the solution. We implement a first order interpolation scheme when traversing between coarse and fine grid regions. Effects of geometry and optical parameters on algorithm performance are evaluated using numerical phantoms (circular, cylindrical, and arbitrary shape) and varying the absorption and scattering coefficients, modulation frequency, and refractive index. The solution on a 3-level BSG is obtained up to 4.2 times faster than the solution on a single fine grid, with minimal increase in numerical error (less than 5%).

    Original languageEnglish (US)
    Pages (from-to)861-878
    Number of pages18
    JournalBiomedical Optics Express
    Volume1
    Issue number3
    DOIs
    StatePublished - Oct 1 2010

    ASJC Scopus subject areas

    • Biotechnology
    • Atomic and Molecular Physics, and Optics

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