Phase Contrast Computed Tomography

X-ray Computed Tomography (CT) is a versatile and widely used medical imaging modality that generates three-dimensional images of the linear x-ray attenuation coefficient. Current CT scanners suffer from a poor contrast-to-noise ratio (CNR) in the soft tissue regime, which demands the additional usage of contrast agent and/or rather high x-ray dose for soft-tissue protocols. There are several strategies being pursued currently in the field to mitigate this issue: Noise can be reduced by using single photon counting detectors, eliminating electronic noise in the imaging chain in the first place. Furthermore, modern iterative reconstruction methods provide an improved CNR by properly accounting for the statistics of the measured data and by more accurate modeling of the CT scanner than traditional analytic reconstruction methods.

Yet another opportunity to improve CNR is the usage of x-ray interferometry that measures the x-ray deflection rather than its attenuation. This approach is generally called phase contrast imaging. Since the first demonstration of the feasibility of using a Talbot-Lau interferometer in the x-ray regime by Franz Pfeiffer in 2006, this technology gained tremendous interest in the x-ray imaging community. Compared to other interferometric methods, it has the main advantage that a conventional x-ray tube can be used, which is a pre-requisite for a wide use in medical imaging. A further advantage is that the method detects simultaneously the deflection, the attenuation, and the loss of coherence of the x-ray beam, thus it provides images of three different tissue properties at the same time.

In this Focus Group, Rudolf Diesel Industry Fellow Dr. Thomas Koehler (Philips Research Laboratories) and his hosts Prof. Franz Pfeiffer (Biomedical Physics) and Prof. Ernst Rummeny (Radiology) investigate the full potential of x-ray phase contrast tomography for medical applications, also in comparison with other forthcoming improvements in CT like the use of energy resolved single photon counting detectors.

In 2015, Hans Fischer Fellow Dr. Kaye Susannah Morgan (Monash University) joined the group. Furthermore, Prof. Franz Pfeiffer was appointed a Carl von Linde Senior Fellow.

Dr. Peter Noël (Diagnostic and Interventional Radiology, University Hospital “Rechts der Isar) as well as doctoral candidates Andreas Fehringer, Wolfgang Noichl and Max von Teuffenbach (all Biomedical Physics, TUM) also work in this Focus Group.

TUM-IAS funded doctoral candidate:
Regine Gradl, Biomedical Physics

Publications by the Focus Group

2019

  • Gradl, R.; Morgan, K. S.; Dierolf, M.; Jud, C.; Hehn, L.; Gunther, B.; Moller, W.; Kutschke, D.; Yang, L.; Stoeger, T.; Pfeiffer, D.; Gleich, B.; Achterhold, K.; Schmid, O.; Pfeiffer, F.: Dynamic <italic>In Vivo</italic> Chest X-ray Dark-Field Imaging in Mice. IEEE Transactions on Medical Imaging 38 (2), 2019, 649-656 mehr…

2018

  • Birnbacher, Lorenz; Maurer, Stefanie; Scheidt, Katharina; Herzen, Julia; Pfeiffer, Franz; Fromme, Tobias: Electron Density of Adipose Tissues Determined by Phase-Contrast Computed Tomography Provides a Measure for Mitochondrial Density and Fat Content. Frontiers in Physiology 9, 2018 mehr…
  • Birnbacher, Lorenz; Viermetz, Manuel; Noichl, Wolfgang; Allner, Sebastian; Fehringer, Andreas; Marschner, Mathias; von Teuffenbach, Maximilian; Willner, Marian; Achterhold, Klaus; Noël, Peter B.; Koehler, Thomas; Herzen, Julia; Pfeiffer, Franz: Tilted grating phase-contrast computed tomography using statistical iterative reconstruction. Scientific Reports 8 (1), 2018 mehr…
  • Braig, Eva-Maria; Birnbacher, Lorenz; Schaff, Florian; Gromann, Lukas; Fingerle, Alexander; Herzen, Julia; Rummeny, Ernst; Noël, Peter; Pfeiffer, Franz; Muenzel, Daniela: Simultaneous wood and metal particle detection on dark-field radiography. European Radiology Experimental 2 (1), 2018 mehr…
  • Braig, Eva; Böhm, Jessica; Dierolf, Martin; Jud, Christoph; Günther, Benedikt; Mechlem, Korbinian; Allner, Sebastian; Sellerer, Thorsten; Achterhold, Klaus; Gleich, Bernhard; Noël, Peter; Pfeiffer, Daniela; Rummeny, Ernst; Herzen, Julia; Pfeiffer, Franz: Direct quantitative material decomposition employing grating-based X-ray phase-contrast CT. Scientific Reports 8 (1), 2018 mehr…
  • De Marco, Fabio; Marschner, Mathias; Birnbacher, Lorenz; Noël, Peter; Herzen, Julia; Pfeiffer, Franz: Analysis and correction of bias induced by phase stepping jitter in grating-based X-ray phase-contrast imaging. Optics Express 26 (10), 2018, 12707 mehr…
  • Eggl, Elena; Grandl, Susanne; Sztrόkay-Gaul, Anikό; Dierolf, Martin; Jud, Christoph; Heck, Lisa; Burger, Karin; Günther, Benedikt; Achterhold, Klaus; Mayr, Doris; Wilkens, Jan J.; Auweter, Sigrid D.; Gleich, Bernhard; Hellerhoff, Karin; Reiser, Maximilian F.; Pfeiffer, Franz; Herzen, Julia: Dose-compatible grating-based phase-contrast mammography on mastectomy specimens using a compact synchrotron source. Scientific Reports 8 (1), 2018 mehr…
  • Gradl, Regine; Dierolf, Martin; Günther, Benedikt; Hehn, Lorenz; Möller, Winfried; Kutschke, David; Yang, Lin; Donnelley, Martin; Murrie, Rhiannon; Erl, Alexander; Stoeger, Tobias; Gleich, Bernhard; Achterhold, Klaus; Schmid, Otmar; Pfeiffer, Franz; Morgan, Kaye Susannah: In vivo Dynamic Phase-Contrast X-ray Imaging using a Compact Light Source. Scientific Reports 8 (1), 2018 mehr…
  • Hehn, Lorenz; Gradl, Regine; Voss, Andrej; Günther, Benedikt; Dierolf, Martin; Jud, Christoph; Willer, Konstantin; Allner, Sebastian; Hammel, Jörg U.; Hessler, Roland; Morgan, Kaye S.; Herzen, Julia; Hemmert, Werner; Pfeiffer, Franz: Propagation-based phase-contrast tomography of a guinea pig inner ear with cochlear implant using a model-based iterative reconstruction algorithm. Biomedical Optics Express 9 (11), 2018, 5330 mehr…
  • Hehn, Lorenz; Morgan, Kaye; Bidola, Pidassa; Noichl, Wolfgang; Gradl, Regine; Dierolf, Martin; Noël, Peter B.; Pfeiffer, Franz: Nonlinear statistical iterative reconstruction for propagation-based phase-contrast tomography. APL Bioengineering 2 (1), 2018, 016105 mehr…
  • Hellbach, Katharina; Baehr, Andrea; De Marco, Fabio; Willer, Konstantin; Gromann, Lukas B.; Herzen, Julia; Dmochewitz, Michaela; Auweter, Sigrid; Fingerle, Alexander A.; Noël, Peter B.; Rummeny, Ernst J.; Yaroshenko, Andre; Maack, Hanns-Ingo; Pralow, Thomas; van der Heijden, Hendrik; Wieberneit, Nataly; Proksa, Roland; Koehler, Thomas; Rindt, Karsten; Schroeter, Tobias J.; Mohr, Juergen; Bamberg, Fabian; Ertl-Wagner, Birgit; Pfeiffer, Franz; Reiser, Maximilian F.: Depiction of pneumothoraces in a large animal model using x-ray dark-field radiography. Scientific Reports 8 (1), 2018 mehr…
  • Lizal, Frantisek; Jedelsky, Jan; Morgan, Kaye; Bauer, Katrin; Llop, Jordi; Cossio, Unai; Kassinos, Stavros; Verbanck, Sylvia; Ruiz-Cabello, Jesús; Santos, Arnoldo; Koch, Edmund; Schnabel, Christian: Experimental methods for flow and aerosol measurements in human airways and their replicas. European Journal of Pharmaceutical Sciences 113, 2018, 95-131 mehr…
  • Töpperwien, Mareike; Gradl, Regine; Keppeler, Daniel; Vassholz, Malte; Meyer, Alexander; Hessler, Roland; Achterhold, Klaus; Gleich, Bernhard; Dierolf, Martin; Pfeiffer, Franz; Moser, Tobias; Salditt, Tim: Propagation-based phase-contrast x-ray tomography of cochlea using a compact synchrotron source. Scientific Reports 8 (1), 2018 mehr…
  • Viermetz, Manuel; Birnbacher, Lorenz; Willner, Marian; Achterhold, Klaus; Pfeiffer, Franz; Herzen, Julia: High resolution laboratory grating-based X-ray phase-contrast CT. Scientific Reports 8 (1), 2018 mehr…

2017

  • Donnelley, Martin; Morgan, Kaye S.; Awadalla, Maged; Farrow, Nigel R.; Hall, Chris; Parsons, David W.: High-resolution mucociliary transport measurement in live excised large animal trachea using synchrotron X-ray imaging. Respiratory Research 18 (1), 2017 mehr…
  • F. Pfeiffer et al.: Pre-clinical dark-field CT imaging of small-animal lung disease models. Proceedings of the 4th Internatonal Meeting on image formation in X-ray CT, 2017 mehr…
  • Gradl, Regine; Dierolf, Martin; Hehn, Lorenz; Günther, Benedikt; Yildirim, Ali Önder; Gleich, Bernhard; Achterhold, Klaus; Pfeiffer, Franz; Morgan, Kaye Susannah: Propagation-based Phase-Contrast X-ray Imaging at a Compact Light Source. Scientific Reports 7 (1), 2017 mehr…
  • Gromann, Lukas B.; De Marco, Fabio; Willer, Konstantin; Noël, Peter B.; Scherer, Kai; Renger, Bernhard; Gleich, Bernhard; Achterhold, Klaus; Fingerle, Alexander A.; Muenzel, Daniela; Auweter, Sigrid; Hellbach, Katharina; Reiser, Maximilian; Baehr, Andrea; Dmochewitz, Michaela; Schroeter, Tobias J.; Koch, Frieder J.; Meyer, Pascal; Kunka, Danays; Mohr, Juergen; Yaroshenko, Andre; Maack, Hanns-Ingo; Pralow, Thomas; van der Heijden, Hendrik; Proksa, Roland; Koehler, Thomas; Wieberneit, Nataly; Rindt, Karsten; Rummeny, Ernst J.; Pfeiffer, Franz; Herzen, Julia: In-vivo X-ray Dark-Field Chest Radiography of a Pig. Scientific Reports 7 (1), 2017 mehr…
  • L. Gromann et al.: A First Feasibility Study on Phantom Samples and In-Vivo Pigs. Proceedings of the Annual Meeting of the Radiological Society of North America, 2017 mehr…
  • M. Donnelley, K. Morgan, and D. W. Parsons: Direct x-ray measurement of airway surface health in animal models: An update on the state-of-the-art. 2017 mehr…
  • P. Bidola, K. Morgan, M. Willner, A. Fehringer, S. Allner, F. Prade, A F H Pfeiffer, K. Achterhold.: Application of sensitive, high-resolution imaging at a commercial lab-based X-ray micro-CT system using propagation-based phase retrieval. Journal of Microscopy 266 (2), 2017, 211-220 mehr…
  • Pavlov, Konstantin M.; Punegov, Vasily I.; Morgan, Kaye S.; Schmalz, Gerd; Paganin, David M.: Deterministic Bragg Coherent Diffraction Imaging. Scientific Reports 7 (1), 2017 mehr…
  • Teuffenbach, Maximilian von; Koehler, Thomas; Fehringer, Andreas; Viermetz, Manuel; Brendel, Bernhard; Herzen, Julia; Proksa, Roland; Rummeny, Ernst J.; Pfeiffer, Franz; Noël, Peter B.: Grating-based phase-contrast and dark-field computed tomography: a single-shot method. Scientific Reports 7 (1), 2017 mehr…

2016

  • Allner, S; Koehler, T; Fehringer, A; Birnbacher, L; Willner, M; Pfeiffer, F; Noël, P B: Bilateral filtering using the full noise covariance matrix applied to x-ray phase-contrast computed tomography. Physics in Medicine and Biology 61 (10), 2016, 3867-3856 mehr…
  • Birnbacher, Lorenz; Willner, Marian; Velroyen, Astrid; Marschner, Mathias; Hipp, Alexander; Meiser, Jan; Koch, Frieder; Schröter, Tobias; Kunka, Danays; Mohr, Jürgen; Pfeiffer, Franz; Herzen, Julia: Experimental Realisation of High-sensitivity Laboratory X-ray Grating-based Phase-contrast Computed Tomography. Scientific Reports 6 (1), 2016 mehr…
  • Donnelley, Martin; Morgan, Kaye; Farrow, Nigel; Siu, Karen; Parsons, David: Non-invasive airway health measurement using synchrotron x-ray microscopy of high refractive index glass microbeads. , AIP Publishing LLC, 2016 mehr…
  • M. Donnelley, M. Awadalla, K. Morgan, N. Farrow, C. Hall, R. Acres, and D. Parsons: Assessing particle mucociliary transit in excised sheep trachea using the Australian Synchrotron imaging and medical beamline. Respirology 21, 2016 mehr…
  • M. Teuffenbach et al.: Iterative reconstruction of grating-based {PCCT} without phase-stepping. Proceedings of the 4th International Meeting on image formation in X-ray CT, 2016 mehr…
  • Macindoe, David; Kitchen, Marcus J; Irvine, Sarah C; Fouras, Andreas; Morgan, Kaye S: Requirements for dynamical differential phase contrast x-ray imaging with a laboratory source. Physics in Medicine and Biology 61 (24), 2016, 8720-8735 mehr…
  • Marschner, M.; Willner, M.; Potdevin, G.; Fehringer, A.; Noël, P. B.; Pfeiffer, F.; Herzen, J.: Helical X-ray phase-contrast computed tomography without phase stepping. Scientific Reports 6 (1), 2016 mehr…
  • Morgan, Kaye S.; Petersen, Timothy C.; Donnelley, Martin; Farrow, Nigel; Parsons, David W.; Paganin, David M.: Capturing and visualizing transient X-ray wavefront topological features by single-grid phase imaging. Optics Express 24 (21), 2016, 24435 mehr…
  • Petersen, Timothy C.; Bishop, Alexis I.; Eastwood, Samuel A.; Paganin, David M.; Morgan, Kaye S.; Morgan, Michael J.: Singularimetry of local phase gradients using vortex lattices and in-line holography. Optics Express 24 (3), 2016, 2259 mehr…
  • Scherer, Kai; Birnbacher, Lorenz; Willer, Konstantin; Chabior, Michael; Herzen, Julia; Pfeiffer, Franz: Correspondence: Quantitative evaluation of X-ray dark-field images for microcalcification analysis in mammography. Nature Communications 7 (1), 2016 mehr…
  • Stahr, Charlene S.; Samarage, Chaminda R.; Donnelley, Martin; Farrow, Nigel; Morgan, Kaye S.; Zosky, Graeme; Boucher, Richard C.; Siu, Karen K. W.; Mall, Marcus A.; Parsons, David W.; Dubsky, Stephen; Fouras, Andreas: Quantification of heterogeneity in lung disease with image-based pulmonary function testing. Scientific Reports 6 (1), 2016 mehr…
  • Yaroshenko, Andre; Pritzke, Tina; Koschlig, Markus; Kamgari, Nona; Willer, Konstantin; Gromann, Lukas; Auweter, Sigrid; Hellbach, Katharina; Reiser, Maximilian; Eickelberg, Oliver; Pfeiffer, Franz; Hilgendorff, Anne: Visualization of neonatal lung injury associated with mechanical ventilation using x-ray dark-field radiography. Scientific Reports 6 (1), 2016 mehr…

2015

  • Aloisio, Isobel A.; Paganin, David M.; Wright, Christopher A.; Morgan, Kaye S.: Exploring experimental parameter choice for rapid speckle-tracking phase-contrast X-ray imaging with a paper analyzer. Journal of Synchrotron Radiation 22 (5), 2015, 1279-1288 mehr…
  • B. Brendel, M. von Teuffenbach, P. B. Noël, F. Pfeiffer, and Th. Koehler: Intensity based iterative reconstruction for differential phase contrast imaging with reconstruction parameter estimation. International Meeting on Fully Three-Dimensional Image Reconstruction in Radiology and Nuclear Medicine (Fully3D, 2015 mehr…
  • Bidola, Pidassa M.; Zanette, Irene; Achterhold, Klaus; Holzner, Christian; Pfeiffer, Franz: Optimization of propagation-based phase-contrast imaging at a laboratory setup. Optics Express 23 (23), 2015, 30000 mehr…
  • Bidola, Pidassa; Stockmar, Marco; Achterhold, Klaus; Pfeiffer, Franz; Pacheco, Mírian L.A.F.; Soriano, Carmen; Beckmann, Felix; Herzen, Julia: Absorption and Phase Contrast X-Ray Imaging in Paleontology Using Laboratory and Synchrotron Sources. Microscopy and Microanalysis 21 (5), 2015, 1288-1295 mehr…
  • Brendel, Bernhard; von Teuffenbach, Maximilian; Noël, Peter B.; Pfeiffer, Franz; Koehler, Thomas: Penalized maximum likelihood reconstruction for x-ray differential phase-contrast tomography. Medical Physics 43 (1), 2015, 188-194 mehr…
  • Eggl, Elena; Schleede, Simone; Bech, Martin; Achterhold, Klaus; Loewen, Roderick; Ruth, Ronald D.; Pfeiffer, Franz: X-ray phase-contrast tomography with a compact laser-driven synchrotron source. Proceedings of the National Academy of Sciences 112 (18), 2015, 5567-5572 mehr…
  • Epple, Franz M.; Ehn, Sebastian; Thibault, Pierre; Koehler, Thomas; Potdevin, Guillaume; Herzen, Julia; Pennicard, David; Graafsma, Heinz; Noel, Peter B.; Pfeiffer, Franz: Phase Unwrapping in Spectral X-Ray Differential Phase-Contrast Imaging With an Energy-Resolving Photon-Counting Pixel Detector. IEEE Transactions on Medical Imaging 34 (3), 2015, 816-823 mehr…
  • F. Pfeiffer: Principles of X-ray Phase- and Darkfield Imaging. nternational Symposium on Biomedical Applications of X-ray Phase Contrast Imaging, 2015 mehr…
  • F. Pfeiffer: Wave-optical X-ray Imaging Phase- and Dark-Field Contrast. International Conference on Medical Image Computing and Computer Assisted Intervention, 2015 mehr…
  • Hahn, Dieter; Thibault, Pierre; Fehringer, Andreas; Bech, Martin; Koehler, Thomas; Pfeiffer, Franz; Noël, Peter B.: Statistical iterative reconstruction algorithm for X-ray phase-contrast CT. Scientific Reports 5 (1), 2015 mehr…
  • K. S. Morgan: High-speed multi-modal x-ray imaging of airway surfaces for in vivo testing of treatment effectiveness. Medical Applications of Synchrotron Radiation, 2015 mehr…
  • K. S. Morgan: Dynamic Phase Contrast X-ray Imaging for Respiratory Research. Spring-8 Symposium, 2015 mehr…
  • K. S. Morgan: X-ray Phase Contrast Imaging of Living Airways. X-ray and Neutron Phase Imaging with Gratings, 2015 mehr…
  • M. von Teuffenbach, B. Brendel, Th. Koehler, P. B. Noël, and F. Pfeiffer: Iterative Reconstruction of Sliding Window PCCT. International Conference on X-ray and Neutron Phase Imaging with Gratings (XNPIG), 2015 mehr…
  • Murrie, R. P.; Paganin, D. M.; Fouras, A.; Morgan, K. S.: Phase contrast x-ray velocimetry of small animal lungs: optimising imaging rates. Biomedical Optics Express 7 (1), 2015, 79 mehr…
  • Prade, F.; Chabior, M.; Malm, F.; Grosse, C.U.; Pfeiffer, F.: Observing the setting and hardening of cementitious materials by X-ray dark-field radiography. Cement and Concrete Research 74, 2015, 19-25 mehr…
  • Ruiz-Yaniz, M.; Koch, F.; Zanette, I.; Rack, A.; Meyer, P.; Kunka, D.; Hipp, A.; Mohr, J.; Pfeiffer, F.: X-ray grating interferometry at photon energies over 180 keV. Applied Physics Letters 106 (15), 2015, 151105 mehr…
  • Ruiz-Yaniz, M.; Zanette, I.; Rack, A.; Weitkamp, T.; Meyer, P.; Mohr, J.; Pfeiffer, F.: X-ray-refractive-index measurements at photon energies above 100 keV with a grating interferometer. Physical Review A 91 (3), 2015 mehr…
  • Sarapata, Adrian; Ruiz-Yaniz, Maite; Zanette, Irene; Rack, Alexander; Pfeiffer, Franz; Herzen, Julia: Multi-contrast 3D X-ray imaging of porous and composite materials. Applied Physics Letters 106 (15), 2015, 154102 mehr…
  • Schaff, Florian; Bech, Martin; Zaslansky, Paul; Jud, Christoph; Liebi, Marianne; Guizar-Sicairos, Manuel; Pfeiffer, Franz: Six-dimensional real and reciprocal space small-angle X-ray scattering tomography. Nature 527 (7578), 2015, 353-356 mehr…
  • Stockmar, Marco; Zanette, Irene; Dierolf, Martin; Enders, Bjoern; Clare, Richard; Pfeiffer, Franz; Cloetens, Peter; Bonnin, Anne; Thibault, Pierre: X-Ray Near-Field Ptychography for Optically Thick Specimens. Physical Review Applied 3 (1), 2015 mehr…
  • Stockmar, Marco; Zanette, Irene; Dierolf, Martin; Enders, Bjoern; Clare, Richard; Pfeiffer, Franz; Cloetens, Peter; Bonnin, Anne; Thibault, Pierre: X-Ray Near-Field Ptychography for Optically Thick Specimens. Physical Review Applied 3 (1), 2015 mehr…
  • Thomsen, M.; Knudsen, E.B.; Willendrup, P.K.; Bech, M.; Willner, M.; Pfeiffer, F.; Poulsen, M.; Lefmann, K.; Feidenhans’l, R.: Prediction of beam hardening artefacts in computed tomography using Monte Carlo simulations. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms 342, 2015, 314-320 mehr…
  • Vogel, Jakob; Schaff, Florian; Fehringer, Andreas; Jud, Christoph; Wieczorek, Matthias; Pfeiffer, Franz; Lasser, Tobias: Constrained X-ray tensor tomography reconstruction. Optics Express 23 (12), 2015, 15134 mehr…
  • Wenz, J.; Schleede, S.; Khrennikov, K.; Bech, M.; Thibault, P.; Heigoldt, M.; Pfeiffer, F.; Karsch, S.: Quantitative X-ray phase-contrast microtomography from a compact laser-driven betatron source. Nature Communications 6 (1), 2015 mehr…
  • Wolf, Johannes; Sperl, Jonathan I.; Schaff, Florian; Schüttler, Markus; Yaroshenko, Andre; Zanette, Irene; Herzen, Julia; Pfeiffer, Franz: Lens-term- and edge-effect in X-ray grating interferometry. Biomedical Optics Express 6 (12), 2015, 4812 mehr…
  • Zanette, I.; Enders, B.; Dierolf, M.; Thibault, P.; Gradl, R.; Diaz, A.; Guizar-Sicairos, M.; Menzel, A.; Pfeiffer, F.; Zaslansky, P.: Ptychographic X-ray nanotomography quantifies mineral distributions in human dentine. Scientific Reports 5 (1), 2015 mehr…

2014

  • Burger, Karin; Koehler, Thomas; Chabior, Michael; Allner, Sebastian; Marschner, Mathias; Fehringer, Andreas; Willner, Marian; Pfeiffer, Franz; Noël, Peter: Regularized iterative integration combined with non-linear diffusion filtering for phase-contrast x-ray computed tomography. Optics Express 22 (26), 2014, 32107 mehr…
  • Herzen, Julia; Willner, Marian S.; Fingerle, Alexander A.; Noël, Peter B.; Köhler, Thomas; Drecoll, Enken; Rummeny, Ernst J.; Pfeiffer, Franz: Imaging Liver Lesions Using Grating-Based Phase-Contrast Computed Tomography with Bi-Lateral Filter Post-Processing. PLoS ONE 9 (1), 2014, e83369 mehr…

2012

  • Raupach, Rainer; Flohr, Thomas: Performance evaluation of x-ray differential phase contrast computed tomography (PCT) with respect to medical imaging. Medical Physics 39 (8), 2012, 4761-4774 mehr…