Thomas Koehler

Rudolf Diesel Industry Fellow


Philips Research Laboratories

Digital Imaging

Franz Pfeiffer and Ernst Rummeny

Focus Group
Phase Contrast Computed Tomography

Short CV

Thomas Koehler studied physics at the Christian-Albrechts-University in Kiel from 1989 to 1994. Immediately after the diploma he started to work at the Philips Research Laboratories in Hamburg on the inverse problem of electro- and magnetocardiography, resulting in a Ph.D. thesis, which was finished in 1998. Since 1998, Thomas Koehler has been working on several projects in the area of inverse problems for different applications, namely computed tomography (CT), diffuse optical tomography (DOT), transmission electron microscopy (TEM), and differential phase contrast imaging (DPCI). His primary focus has been the development of reconstruction algorithms for CT and adjacent topics. Major contributions in the field of CT are in the area of approximate and exact reconstructions algorithms for helical cone-beam CT, where he covered the mathematics of reconstruction, the practical aspects arising in clinical applications, and the implementation on dedicated hardware. Furthermore, he contributed to the field of iterative reconstruction, and he is currently working together with the Department of Radiology at TUM on the forthcoming generation of iterative reconstruction algorithms for CT. During the last few years, he has gained interest in the emerging field of DPCI, where he has worked on both projection imaging as well as on tomographic imaging.

Research Interests

  • Tomographic imaging
  • Inverse problems
  • Computed tomography
  • X-ray imaging
  • Phase contrast x-ray imaging
  • Medical imaging

Selected Publications

  • Schirra, C. O.; Roessl, E.; Koehler, T.; Brendel, B.; Thran, A.; Pan, D.; Anastasio, M. A.; Proksa, R.: Statistical Reconstruction of Material Decomposed Data in Spectral CT. IEEE Transactions on Medical Imaging 32 (7), 2013, 1249-1257.
  • Köhler, Thomas; Jürgen Engel, Klaus; Roessl, Ewald: Noise properties of grating-based x-ray phase contrast computed tomography. Med. Phys. 38 (S1), 2011, S106.
  • Köhler, Thomas; Brendel, Bernhard; Roessl, Ewald: Iterative reconstruction for differential phase contrast imaging using spherically symmetric basis functions. Med. Phys. 38 (8), 2011, 4542.
  • Pfeiffer, F.; David, C.; Bunk, O.; Donath, T.; Bech, M.; Le Duc, G.; Bravin, A.; Cloetens, P.: Region-of-Interest Tomography for Grating-Based X-Ray Differential Phase-Contrast Imaging. Phys. Rev. Lett. 101 (16), 2008.
  • Ziegler, A.; Köhler, Th.; Proksa, R.: Noise and resolution in images reconstructed with FBP and OSC algorithms for CT. Med. Phys. 34 (2), 2007, 585.

Publications as TUM-IAS-Fellow


  • Frank, Manuela; Gassert, Florian; Urban, Theresa; Willer, Konstantin; Noichl, Wolfgang; Schick, Rafael; Schultheiß, Manuel; Viermetz, Manuel; Gleich, Bernhard; De Marco, Fabio; Herzen, Julia; Koehler, Thomas; Engel, Klaus; Renger, Bernhard; Gassert, Felix; Sauter, Andreas; Fingerle, Alexander; Haller, Bernhard; Makowski, Marcus; Pfeiffer, Franz: Dark-field Chest X-ray Imaging for the Assessment of COVID‑19‑Pneumonia. , 2022 mehr… BibTeX Volltext ( DOI )
  • Urban, Theresa; Gassert, Florian T.; Frank, Manuela; Willer, Konstantin; Noichl, Wolfgang; Buchberger, Philipp; Schick, Rafael C.; Koehler, Thomas; Bodden, Jannis H.; Fingerle, Alexander A.; Sauter, Andreas P.; Makowski, Marcus R.; Pfeiffer, Franz; Pfeiffer, Daniela: Qualitative and Quantitative Assessment of Emphysema Using Dark-Field Chest Radiography. Radiology 303 (1), 2022, 119-127 mehr… BibTeX Volltext ( DOI )
  • Viermetz, Manuel; Gustschin, Nikolai; Schmid, Clemens; Haeusele, Jakob; Teuffenbach, Maximilian von; Meyer, Pascal; Bergner, Frank; Lasser, Tobias; Proksa, Roland; Koehler, Thomas; Pfeiffer, Franz: Dark-field computed tomography reaches the human scale. Proceedings of the National Academy of Sciences 119 (8), 2022, e2118799119 mehr… BibTeX Volltext ( DOI )


  • Willer, Konstantin; Fingerle, Alexander A; Noichl, Wolfgang; De Marco, Fabio; Frank, Manuela; Urban, Theresa; Schick, Rafael; Gustschin, Alex; Gleich, Bernhard; Herzen, Julia; Koehler, Thomas; Yaroshenko, Andre; Pralow, Thomas; Zimmermann, Gregor S; Renger, Bernhard; Sauter, Andreas P; Pfeiffer, Daniela; Makowski, Marcus R; Rummeny, Ernst J; Grenier, Philippe A; Pfeiffer, Franz: X-ray dark-field chest imaging for detection and quantification of emphysema in patients with chronic obstructive pulmonary disease: a diagnostic accuracy study. The Lancet Digital Health 3 (11), 2021, e733-e744 mehr… BibTeX Volltext ( DOI )


  • 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… BibTeX Volltext ( DOI )


  • 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… BibTeX Volltext ( DOI )


  • 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… BibTeX Volltext ( DOI )
  • 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… BibTeX Volltext ( DOI )


  • 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… BibTeX Volltext ( DOI )
  • 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… BibTeX Volltext ( DOI )