Wuppertal 2015 – scientific programme

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ST: Fachverband Strahlen- und Medizinphysik

ST 1: Biomedical Imaging I

ST 1.7: Talk

Monday, March 9, 2015, 15:30–15:45, BZ.08.02 (HS 3)

Tilted grating phase-contrast computed tomography — •Lorenz Birnbacher, Marian Willner, Mathias Marschner, Julia Herzen, and Franz Pfeiffer — Lehrstuhl für Biomedizinische Physik, Physik-Department & Institut für Medizintechnik, Technische Universität München

An X-ray Talbot-Lau interferometer consists of three gratings which have parallelly oriented grating lines. Via shifting one of those gratings perpendicularly with respect to its grating orientation - the so-called phase-stepping - one measures the differential phase-contrast (DPC) signal of structures in scanning direction (perpendicular to the grating lines). However, due to the grating orientation the DPC signal is insensitive in the direction of the grating lines (parallel to the grating lines).

One approach to overcome this loss of sensitivity is to tilt the gratings by 45 degrees with respect to the tomography axis and perform a tomographic scan during a full sample rotation. Combining two corresponding DPC projections of 0 and 180 degrees with a two-directional integration algorithm, a phase projection sensitive in both directions can be retrieved leading to a fully sensitive tomographic scan of 180 degrees.

We show the results of this method using a high-sensitivity phase-contrast computed tomography (PC-CT) setup and compare the results with standard PC-CT scans with respect to feature detectability of biomedical samples.