title: Contrast-to-noise ratio optimization for a prototype phase-contrast computed tomography scanner.
abstract: In the field of biomedical X-ray imaging, novel techniques, such as phase-contrast and dark-field imaging, have the potential to enhance the contrast and provide complementary structural information about a specimen. In this paper, a first prototype of a preclinical X-ray phase-contrast CT scanner based on a Talbot-Lau interferometer is characterized. We present a study of the contrast-to-noise ratios for attenuation and phase-contrast images acquired with the prototype scanner. The shown results are based on a series of projection images and tomographic data sets of a plastic phantom in phase and attenuation-contrast recorded with varying acquisition settings. Subsequently, the signal and noise distribution of different regions in the phantom were determined. We present a novel method for estimation of contrast-to-noise ratios for projection images based on the cylindrical geometry of the phantom. Analytical functions, representing the expected signal in phase and attenuation-contrast for a circular object, are fitted to individual line profiles of the projection data. The free parameter of the fit function is used to estimate the contrast and the goodness of the fit is determined to assess the noise in the respective signal. The results depict the dependence of the contrast-to-noise ratios on the applied source voltages, the number of steps of the phase stepping routine, and the exposure times for an individual step. Moreover, the influence of the number of projection angles on the image quality of CT slices is investigated. Finally, the implications for future imaging purposes with the scanner are discussed.
authors.affiliation: Lehrstuhl für Biomedizinische Physik, Physik-Department & Institut für Medizintechnik, Technische Universität München, 85748 Garching, Germany.
authors.forename: Mark
authors.initials: M
authors.lastname: Müller
authors.affiliation: Lehrstuhl für Biomedizinische Physik, Physik-Department & Institut für Medizintechnik, Technische Universität München, 85748 Garching, Germany.
authors.forename: Andre
authors.initials: A
authors.lastname: Yaroshenko
authors.affiliation: Lehrstuhl für Biomedizinische Physik, Physik-Department & Institut für Medizintechnik, Technische Universität München, 85748 Garching, Germany.
authors.forename: Astrid
authors.initials: A
authors.lastname: Velroyen
authors.affiliation: Medical Radiation Physics, Lund University, Barngatan 2:1, 221 85 Lund, Sweden.
authors.forename: Martin
authors.initials: M
authors.lastname: Bech
authors.affiliation: Lehrstuhl für Biomedizinische Physik, Physik-Department & Institut für Medizintechnik, Technische Universität München, 85748 Garching, Germany.
authors.forename: Arne
authors.initials: A
authors.lastname: Tapfer
authors.affiliation: Bruker microCT, Kartuizersweg 3B, B-2550 Kontich, Belgium.
authors.forename: Bart
authors.initials: B
authors.lastname: Pauwels
authors.affiliation: Bruker microCT, Kartuizersweg 3B, B-2550 Kontich, Belgium.
authors.forename: Peter
authors.initials: P
authors.lastname: Bruyndonckx
authors.affiliation: Bruker microCT, Kartuizersweg 3B, B-2550 Kontich, Belgium.
authors.forename: Alexander
authors.initials: A
authors.lastname: Sasov
authors.affiliation: Lehrstuhl für Biomedizinische Physik, Physik-Department & Institut für Medizintechnik, Technische Universität München, 85748 Garching, Germany.
authors.forename: Franz
authors.initials: F
authors.lastname: Pfeiffer
mesh_terms: D004867:Equipment Design; D019544:Equipment Failure Analysis; D019047:Phantoms, Imaging; D010865:Pilot Projects; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000295:instrumentation* / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D059629:Signal-To-Noise Ratio; D014057:Tomography, X-Ray Computed / Q000295:instrumentation*