Erste untersuchungen zur anwendung der linearen signalübertragungstheorie in der auswertung diaphanoskopischer untersuchungen am beispiel der rheumadiagnostik

Translated title of the contribution: Initial investigations of the application of linear signal transfer theory to tissue optics

J. Beuthan, H. J. Cappius, A. Hielscher, M. Hopf, A. Klose, U. Netz

    Research output: Contribution to journalArticlepeer-review

    Abstract

    Rheumatoid arthritis affecting the small joints - in particular the fingers - has advantageous geometry for the transmission of near-infrared (NIR) light. Examination of the optical properties of tissues has revealed that as a result of changes to the capsule and synovial fluid there is a considerable increase in photon scattering already in the early stages of the disease - in particular around 685 nm. This suggests the appropriateness of analysing the photon density profile resulting from punctiform irradiation of the joint. In a first approximation, the point spread function of transmitted photon density is confirmed to be proportional to a Gauss distribution, as suggested by Arridge. In accordance with the linear signal transfer theory, therefore, it is possible to establish a virtual transfer system described by a first-order differential equation. (The tissue optical conditions μa ≪ μ′s and μa ≈ constant (μa = absorption coefficient) were assumed). The parameter μ′s (= reduced scattering coefficient) was determined by linear approximation of the Gauss distribution to the calculated or measured point spread function. For selected patient data, the μ′s was determined in healthy and diseased finger joints (e.g. 10.1 cm-1 and 26.8 cm-1, respectively), and the results were in good agreement with those obtained experimentally.

    Translated title of the contributionInitial investigations of the application of linear signal transfer theory to tissue optics
    Original languageGerman
    Pages (from-to)298-303
    Number of pages6
    JournalBiomedizinische Technik
    Volume46
    Issue number11
    DOIs
    StatePublished - 2001

    Keywords

    • Optical parameters
    • Rheumatoid arthritis
    • Scattering media
    • System theory
    • Transport theory

    ASJC Scopus subject areas

    • Biomedical Engineering

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