The projection approximation and edge contrast for x-ray propagation-based phase contrast imaging of a cylindrical edge

Kaye Susannah Morgan, Karen Kit Wan Siu, David Paganin

    Research output: Contribution to journalArticleResearchpeer-review

    35 Citations (Scopus)

    Abstract

    We examine the projection approximation in the context of propagation-based phase contrast imaging using hard x-rays. Specifically, we consider the case of a cylinder or a rounded edge, as a simple model for the edges of many biological samples. The Argand-plane signature of a propagation-based phase contrast fringe from the edge of a cylinder is studied, and the evolution of this signature with propagation. This, along with experimental images obtained using a synchrotron source, reveals how propagation within the scattering volume is not fully described in the projection approximation s ray-based approach. This means that phase contrast fringes are underestimated by the projection approximation at a short object-to-detector propagation distance, namely a distance comparable to the free-space propagation within the volume. This failure of the projection approximation may become non-negligible in the detailed study of small anatomical features deep within a large body. Nevertheless, the projection approximation matches the exact solution for a larger propagation distance typical of those used in biomedical phase contrast imaging.
    Original languageEnglish
    Pages (from-to)9865 - 9878
    Number of pages14
    JournalOptics Express
    Volume18
    Issue number10
    DOIs
    Publication statusPublished - 2010

    Cite this