X-ray phase-contrast imaging offers a new way to look into the internal structures of objects. At hard x-ray energies the phase shift in some materials is many times the attenuation of intensity, promising greater image details with less radiation. Grating-based differential phase contrast imaging techniques work with compact x-ray sources and are potentially well suited for biomedical applications. Taking the concept to practical imaging systems still faces major challenges, including the limitations associated with mechanical phase stepping, and loss of phase information in dense or porous materials such as bone, lung or metallic implants. We report on advances of grating-based imaging towards main stream applications which address these challenges. We describe an electronic fringe scanning method for retrieving the phase signal without any mechanical motion, thereby removing the constraint in speed, accuracy and flexibility. Recognizing that phase is the primary source of contrast in weakly absorbing materials while the classic intensity attenuation is dominant in dense materials, we developed an adaptive algorithm to combine both pieces of information in the Fourier domain to produce a phase-contrast enhanced image. These methods are broadly applicable for both projection and tomographic imaging of complex objects of varying attenuation and phase properties.
Citation: Proceedings of the National Academy of Sciences of the United States of America
Pub Type: Journals
X-ray, Phase Contrast, Imaging