Thomas Flohr

Associate professor

Thomas Flohr studied physics at the Friedrich Alexander University Erlangen-Nürnberg, Germany, where he received his PhD in 1989. Following his graduation, he joined the computed tomography (CT) research and development department at Siemens Healthcare, Germany (now Siemens Healthineers). During his career spanning more than 30 years at the company, he was closely involved in the development of modern multi-slice CT, the development and clinical introduction of cardiac CT, and the establishment of dual-source CT. More recently, his primary research focus was the development and clinical introduction of photon-counting detector CT. Since 2023, he has been working part-time as a medical physicist in the Department of Radiology and Nuclear Medicine at the Maastricht UMC+.

His primary research interest centers on the physics-based evaluation of the benefits and potential limitations of photon-counting detector CT (PCD-CT) in clinical routine use. In this context, his work focuses on evaluating new clinical applications, exploring the possibilities of spectral imaging and imaging at ultra-high spatial resolution, and investigating the technology's potential to reduce both radiation and contrast media doses.

Department of Radiology and Nuclear Medicine
Adress: Debyelaan 25, 6229HX Maastricht

2026
- Demmert, T. T., Schikorra, T., Heining, S. M., Specovius, A., Klambauer, K., Moser, L. J., Mergen, V., Schmidt, B., Flohr, T., Eberhard, M., & Alkadhi, H. (2026). Advanced Iterative Metal Artifact Reduction With Intrinsic Spectral Information From Photon-counting Detector Computed Tomography: Improving the Assessment of Metal-bone Interface. Investigative Radiology, 61(11), 766-773. https://doi.org/10.1097/RLI.0000000000001282
- Jeukens, C. R. L. P. N., Pinckaers, F. M. E., Martens, B., Jasper, S., Wildberger, J. E., & Flohr, T. (2026). Influence of X-ray Tube Voltage on Computed Tomography Values and Contrast-Noise Ratios in Virtual Monoenergetic Images in routine clinical Photon Counting Detector Computed Tomography: Does kV Still Matter? Investigative Radiology. Advance online publication. https://doi.org/10.1097/RLI.0000000000001312
- Kupfer, S., Klambauer, K., Puippe, G., Weisskopf, M., Pfammatter, T., Flohr, T., & Kobe, A. (2026). Intra-osseous Ice Ball Visualization During Cryoablation Using Photon-Counting Detector Computed Tomography: An In-Vivo Swine Pilot Study. Cardiovascular and Interventional Radiology, 49(9), 1886-1892. https://doi.org/10.1007/s00270-025-04343-w
- Tognella, A., Flohr, T., Froehlich, J. M., Nowak, T., Fischer, M. A., Alkadhi, H., & Ghafoor, S. (2026). Liver Fat and Iron Quantification With Spectral Localizer Radiographs From Photon-counting Detector CT. Investigative Radiology, 61(9), 628-635. https://doi.org/10.1097/RLI.0000000000001268
- Jeukens, C. R. L. P. N., Martens, B., Vandewall, J., Jasper, S., Schrijnemaekers, G., Wildberger, J. E., & Flohr, T. G. (2026). A Practical Rule-of-Thumb to Adapt Contrast Media Dose in Photon-counting Detector CT. Investigative Radiology, 61(8), 527-536. https://doi.org/10.1097/RLI.0000000000001253
- Demmert, T. T., Klambauer, K., Schmidt, B., Mergen, V., Moser, L. J., Maintz, P. N., Allmendinger, T., Flohr, T., Pietsch, H., Eberhard, M., & Alkadhi, H. (2026). High-Z Contrast Media for Coronary Photon-counting Detector CT Angiography Improved Quantification of Calcified Stenoses. Investigative Radiology, 61(8), 568-574. https://doi.org/10.1097/RLI.0000000000001262
- Husain, A. A.-H., Dogan, S., Mergen, V., Demmert, T. T., Alkadhi, H., Flohr, T., Essig, H., Stadlinger, B., & Burian, E. (2026). Photon-Counting Detector CT-Based Virtual Monoenergetic Imaging With Metal Artifact Reduction for Endodontic Diagnostics. International Dental Journal, 76(4), Article 109547. https://doi.org/10.1016/j.identj.2026.109547
- Kekelidze, M., Garcia-Figueiras, R., Kolmos, M., Silberbrandt, A. R., Olech, W. E., Borgbjerg, J., Sliwicka, O., Flohr, T., Alkadhi, H., & Miron Mombiela, R. (2026). Spectral CT in renal cell carcinoma: the promising role of dual-energy and photon-counting techniques. Abdominal Radiology. https://doi.org/10.1007/s00261-026-05578-y
- Flohr, T. G., & Postma, A. A. (2026). SWOT to know: Is the future of photon-counting detector CT in neuroradiology uncertain? European Radiology, 36(5), 3890-3892. https://doi.org/10.1007/s00330-026-12400-2
- Demmert, T. T., Klambauer, K., Moser, L. J., Michel, J., Kasel, M., Manka, R., Mergen, V., Flohr, T., Eberhard, M., & Alkadhi, H. (2026). Ultra-high resolution photon-counting detector coronary CT angiography: diagnostic accuracy in patients with high Agatston scores. European Radiology, 36(5), 4017-4025. https://doi.org/10.1007/s00330-025-12158-z
- Al-Haj Husain, A., Demmert, T. T., Klambauer, K., Maintz, P., Flohr, T., Essig, H., Wagner, M. E. H., Sandhu, S., Burian, E., Stadlinger, B., Alkadhi, H., & Mergen, V. (2026). Optimization of dental implant imaging using photon-counting detector computed tomography in oral and maxillofacial surgery: an ex vivo study. European Radiology Experimental, 10(1), Article 46. https://doi.org/10.1186/s41747-026-00710-5
- Springer, S., Martens, B., Flohr, T., & Jeukens, C. (2026). Phantom-derived method for improving accurate material decomposition in photon-counting detector CT. European Radiology Experimental, 10(1), Article 39. https://doi.org/10.1186/s41747-026-00705-2
- Stammen, L., Hoeijmakers, E. J. I., Flohr, T. G., Gietema, H. A., Vandewall, J., Wildberger, J. E., Jeukens, C. R. L. P. N., & Martens, B. (2026). Reducing contrast media dosage for pulmonary embolism CTPA in PCD-CT: a comparative study of EID-CT and PCD-CT in the era of individualized protocolling. European Radiology, 36(4), 3206-3215. https://doi.org/10.1007/s00330-025-12054-6
- Sandhu, S., Husain, A. A.-H., Mergen, V., Demmert, T. T., Alkadhi, H., Flohr, T., Burian, E., Stadlinger, B., Kessler, P., Essig, H., & Wagner, M. E. H. (2026). Comparative evaluation of photon-counting detector CT and cone-beam CT in the assessment of simulated mandibular trauma. Journal of Stomatology Oral and Maxillofacial Surgery, 127(2), Article 102603. https://doi.org/10.1016/j.jormas.2025.102603
- Al-Haj Husain, A., Mergen, V., Al-Haj Husain, N., Alkadhi, H., Demmert, T. T., Essig, H., Winklhofer, S., Flohr, T., Valdec, S., Dogan, S., Burian, E., & Stadlinger, B. (2026). Photon-counting detector vs. cone-beam CT in endodontics: a study of simulated endodontic conditions, treatments, and associated complications. BMC Oral Health, 26(1), Article 344. https://doi.org/10.1186/s12903-026-07765-1
- Klambauer, K., Demmert, T. T., Moser, L. J., Mergen, V., Senn, T. C., Kolb, B., Eberhard, M., Jost, G., Pietsch, H., Alkadhi, H., & Flohr, T. (2026). The potential of high-Z contrast media for vessel visualization near metal implants: a photon-counting detector CT phantom study with virtual monoenergetic images and iterative metal artifact reduction. Quantitative Imaging in Medicine and Surgery, 16(3), 1-14. Article 215. https://doi.org/10.21037/qims-2025-1861
- Pinckaers, F. M. E., Wagemans, B. A. J. M., Huijberts, I., Flohr, T. G., Wildberger, J. E., & Postma, A. A. (2026). Leveraging the Potential of Ultra-High Resolution Photon Counting Detector CT Angiography of the Cerebral Vasculature by Using Low kVp and Sharp Kernels. Investigative Radiology. Advance online publication. https://doi.org/10.1097/RLI.0000000000001285
- Bierens, J., Kuijpers, J., Pinckaers, F. M. E., Saba, L., Smits, L. J. M., van Oostenbrugge, R. J., Flohr, T., Kooi, M. E., & Postma, A. A. (2026). Spectral Photon-Counting Detector CT for Comprehensive Evaluation of Carotid Plaque and Stenosis. Investigative Radiology. Advance online publication. https://doi.org/10.1097/RLI.0000000000001291
- Maintz, P. N., Demmert, T. T., Flohr, T., Klambauer, K., Moser, L. J., Mergen, V., Eberhard, M., Froehlich, J. M., & Alkadhi, H. (2026). Quantification of myocardial iron and fat-an experimental study with photon-counting detector CT. British Journal of Radiology, 99(1181), 866–871. https://doi.org/10.1093/bjr/tqag020
2025
- Heuts, S., Kawczynski, M. J., Lemmens, M. J., Vernooy, K., Bidar, E., Flohr, T., Wildberger, J. E., Smulders, M. W., & Mihl, C. (2025). Accuracy of Photon-counting Detector CT Angiography for the Diagnosis of Obstructive Coronary Artery Disease: A Bayesian Diagnostic Test Accuracy Meta-Analysis. Radiology. Cardiothoracic imaging, 7(6), Article e250313. https://doi.org/10.1148/ryct.250313
- Klambauer, K., Flohr, T., Moser, L. J., Mergen, V., Eberhard, M., Prokein, A., Alkadhi, H., Jost, G., & Pietsch, H. (2025). Contrast media and radiation dose optimization with task-based automatic keV selection: a proof-of-concept study with photon-counting detector CT. European Radiology, 35(12), 7975-7984. https://doi.org/10.1007/s00330-025-11738-3
- Flohr, T., & Sühling, M. (2025). Artificial intelligence integration into the CT system with a focus on CT planning and scanning-review. British Journal of Radiology, 98(1175), 1766-1774. https://doi.org/10.1093/bjr/tqaf129
- Remy-Jardin, M., Flohr, T., & Remy, J. (2025). Thoracic applications of photon-counting CT: where are we after 3 years of clinical implementation? British Journal of Radiology, 98(1175), 1813-1820. https://doi.org/10.1093/bjr/tqaf026
- Al-Haj Husain, A., Mergen, V., Sandhu, S., Wagner, M. E. H., Demmert, T. T., Alkadhi, H., Burian, E., Flohr, T., Stadlinger, B., Kessler, P., Lie, S. A. N., & Essig, H. (2025). Postoperative assessment of fracture reduction and osteosynthesis materials using photon-counting detector CT in maxillofacial trauma - a pilot study. Oral and Maxillofacial Surgery, 29(1), Article 171. https://doi.org/10.1007/s10006-025-01470-z
- Remy-Jardin, M., Duhamel, A., Delobelle, M., Bervar, J.-F., Flohr, T., & Remy, J. (2025). Lung microvasculopathy in chronic thromboembolic pulmonary hypertension: high-resolution findings with photon-counting detector CT in 29 patients. European Radiology, 35(10), 6369-6381. https://doi.org/10.1007/s00330-025-11561-w
- Schalla, S., Wildberger, J. E., Ramaekers, M. J. F. G., Mihl, C., McDermott, M. C., Stammen, L., Vernooy, K., & Flohr, T. G. (2025). Imaging of Cardiovascular Implantable Electronic Device Leads With Photon-Counting Detector Computed Tomography. Investigative Radiology, 60(9), 616-625. https://doi.org/10.1097/RLI.0000000000001177
- Kerber, B., Hüllner, M., Maurer, A., Flohr, T., Ulrich, S., Lichtblau, M., Frauenfelder, T., & Franckenberg, S. (2025). Photon-Counting Detector CT Iodine Maps Versus SPECT/CT: Advancing Lung Perfusion Imaging in Chronic Thromboembolic Pulmonary Hypertension. Investigative Radiology, 60(9), 569-576. https://doi.org/10.1097/RLI.0000000000001163
- Zijta, F. M., Truyens, A., Weijers, R. E., Wildberger, J. E., Emans, P. J., & Flohr, T. (2025). The emerging role of photon-counting detector CT: primary experience on the integrated assessment of acute knee injuries. European Radiology Experimental, 9(1), Article 71. https://doi.org/10.1186/s41747-025-00616-8
- Aizaz, M., Bierens, J., Gijbels, M. J. J., Schreuder, T. H. C. M. L., van Orshoven, N. P., Daemen, J.-W. H. C., Mess, W. H., Flohr, T., van Oostenbrugge, R. J., Postma, A. A., & Kooi, M. E. (2025). Differentiation of Atherosclerotic Carotid Plaque Components With Dual-Energy Computed Tomography. Investigative Radiology, 60(8), 508-516. https://doi.org/10.1097/RLI.0000000000001153
- Moser, L. J., Klambauer, K., Diaz Machicado, M. C., Frey, D., Mergen, V., Eberhard, M., Nowak, T., Schmidt, B., Flohr, T., Distler, O., & Alkadhi, H. (2025). In Vivo Bone Mineral Density Assessment With Spectral Localizer Radiographs From Photon-Counting Detector CT: Prospective Comparison With DXA. Investigative Radiology, 60(8), 535-542. https://doi.org/10.1097/RLI.0000000000001159
- Hoeijmakers, E. J. I., Martens, B., Wildberger, J. E., Flohr, T. G., & Jeukens, C. R. L. P. N. (2025). Objective assessment of diagnostic image quality in CT scans: what radiologists and researchers need to know. Insights into Imaging, 16(1), Article 154. https://doi.org/10.1186/s13244-025-02037-y
- Kerber, B., Flohr, T., Ulrich, S., Lichtblau, M., Frauenfelder, T., & Franckenberg, S. (2025). Photon-Counting CT Iodine Maps for Diagnosing Chronic Pulmonary Thromboembolism: A Pilot Study. Investigative Radiology, 60(5), 328-333. https://doi.org/10.1097/RLI.0000000000001134
- Klambauer, K., Flohr, T., Moser, L. J., Mergen, V., Eberhard, M., Prokein, A., Alkadhi, H., Pietsch, H., & Jost, G. (2025). Reducing contrast media and radiation dose in CT angiography at low tube voltage: animal study with photon-counting detector CT. European Radiology Experimental, 9(1), Article 37. https://doi.org/10.1186/s41747-025-00577-y
- Klambauer, K., Lisi, C., Moser, L. J., Mergen, V., Flohr, T., Eberhard, M., & Alkadhi, H. (2025). Multienergy Cardiovascular CT Imaging: Current State and Future. British Journal of Radiology, 98(1167), 321-329. https://doi.org/10.1093/bjr/tqae246
- Hardy, J. C. A., Crombag, G. A. J. C., Peters, N. H. G. M., Hermsen, R., Willigers, J. L., Nobel, J. M., Wildberger, J. E., Flohr, T. G., & Postma, A. A. (2025). Bullet characterization using Photon-Counting detector CT: A phantom study with intact bullets. European Journal of Radiology, 183, Article 111898. https://doi.org/10.1016/j.ejrad.2024.111898
2024
- McDermott, M. C., Sartoretti, T., Stammen, L., Martens, B., Jost, G., Pietsch, H., Gutjahr, R., Schmidt, B., Flohr, T. G., Alkadhi, H., & Wildberger, J. E. (2024). Countering Calcium Blooming With Personalized Contrast Media Injection Protocols: The 1-2-3 Rule for Photon-Counting Detector CCTA. Investigative Radiology, 59(10), 684-690. https://doi.org/10.1097/RLI.0000000000001078
- Sartoretti, T., McDermott, M. C., Stammen, L., Martens, B., Moser, L. J., Jost, G., Pietsch, H., Gutjahr, R., Nowak, T., Schmidt, B., Flohr, T. G., Wildberger, J. E., & Alkadhi, H. (2024). Tungsten-Based Contrast Agent for Photon-Counting Detector CT Angiography in Calcified Coronaries: Comparison to Iodine in a Cardiovascular Phantom. Investigative Radiology, 59(10), 677-683. https://doi.org/10.1097/RLI.0000000000001073
- Hoeijmakers, E. J. I., Stammen, L., Wildberger, J. E., Eijsvoogel, N. G., Hersbach, J. M., Pernot, J. C. J. G., Flohr, T. G., Martens, B., & Jeukens, C. R. L. P. N. (2024). PCD-CT enables contrast media reduction in abdominal imaging compared to an individualized kV-adapted contrast media injection protocol on EID-CT. European Journal of Radiology, 179, Article 111680. https://doi.org/10.1016/j.ejrad.2024.111680

Overview

Latest news & events

Prof. dr. J. Terpstra Award Amée Buziau

9 November 2026

Luisa Wensky wins the FIGON PhD Student Competition

3 November 2026

Thomas Flohr

Associate professor