title: Helical X-ray phase-contrast computed tomography without phase stepping.
abstract: X-ray phase-contrast computed tomography (PCCT) using grating interferometry provides enhanced soft-tissue contrast. The possibility to use standard polychromatic laboratory sources enables an implementation into a clinical setting. Thus, PCCT has gained significant attention in recent years. However, phase-contrast CT scans still require significantly increased measurement times in comparison to conventional attenuation-based CT imaging. This is mainly due to a time-consuming stepping of a grating, which is necessary for an accurate retrieval of the phase information. In this paper, we demonstrate a novel scan technique, which directly allows the determination of the phase signal without a phase-stepping procedure. The presented work is based on moiré fringe scanning, which allows fast data acquisition in radiographic applications such as mammography or in-line product analysis. Here, we demonstrate its extension to tomography enabling a continuous helical sample rotation as routinely performed in clinical CT systems. Compared to standard phase-stepping techniques, the proposed helical fringe-scanning procedure enables faster measurements, an extended field of view and relaxes the stability requirements of the system, since the gratings remain stationary. Finally, our approach exceeds previously introduced methods by not relying on spatial interpolation to acquire the phase-contrast signal.
authors.affiliation: Lehrstuhl für Biomedizinische Physik, Physik-Department &Institut für Medizintechnik, Technische Universität München, 85748 Garching, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Marschner
authors.affiliation: Lehrstuhl für Biomedizinische Physik, Physik-Department &Institut für Medizintechnik, Technische Universität München, 85748 Garching, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Willner
authors.affiliation: Lehrstuhl für Biomedizinische Physik, Physik-Department &Institut für Medizintechnik, Technische Universität München, 85748 Garching, Germany.
authors.forename: G
authors.initials: G
authors.lastname: Potdevin
authors.affiliation: Lehrstuhl für Biomedizinische Physik, Physik-Department &Institut für Medizintechnik, Technische Universität München, 85748 Garching, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Fehringer
authors.affiliation: Lehrstuhl für Biomedizinische Physik, Physik-Department &Institut für Medizintechnik, Technische Universität München, 85748 Garching, Germany.|Institut für diagnostische und interventionelle Radiologie, Klinikum rechts der Isar, Technische Universität München, 81675 München, Germany.
authors.forename: P B
authors.initials: PB
authors.lastname: Noël
authors.affiliation: Lehrstuhl für Biomedizinische Physik, Physik-Department &Institut für Medizintechnik, Technische Universität München, 85748 Garching, Germany.|Institut für diagnostische und interventionelle Radiologie, Klinikum rechts der Isar, Technische Universität München, 81675 München, Germany.
authors.forename: F
authors.initials: F
authors.lastname: Pfeiffer
authors.affiliation: Lehrstuhl für Biomedizinische Physik, Physik-Department &Institut für Medizintechnik, Technische Universität München, 85748 Garching, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Herzen