Imaging

How photon-counting CT has redefined clinical decision-making

Photon-counting computed tomography (CT) is a groundbreaking innovation in medical imaging and is set to redefine healthcare delivery. With over 1.5 million patients scanned worldwide since its introduction in 2021, photon-counting CT is already proving to be a game-changer in diagnostic imaging.

Andrea Lutz

Published on April 11, 2025

Photon-counting CT is transforming clinical practice. By “counting” each X-ray photon that passes through the patient, this technology enables the acquisition of detailed images that include both anatomical and functional information.

Profound clinical impact

Photon-counting CT technology supports precise detection and evaluation of small structures at low radiation doses, reduces artifacts, and improves diagnostic accuracy for fast decision-making and optimized imaging workflows.

Photon-counting CT is changing the game, the field, the language, the priorities, and in the end, it will change the entire infrastructure of diagnostic medicine [1].
Filippo Cademartiri, MD, PhD, IRCCS SYNLAB SDN, Naples, Italy

Previously, NAEOTOM Alpha¹ was the only commercially available whole-body CT system with photon-counting technology for clinical use. Now, the NAEOTOM Alpha class¹ includes a second dual-source scanner and the world’s first single-source whole-body photon-counting CT system. This will make this technology available to even more healthcare providers and their patients.

The infographic shows that 54% of patients examined with photon-counting CT were spared invasive coronary angiography.

Clinical image of a heart acquired with photon-counting CT

Infographic indicates that 100% of CSF-venous fistulas were found with photon-counting CT

Photon-counting CT image of the abdomen in 3D

Clinical image of a head acquired with photon-counting CT

Infographic shows that photon-counting CT images show up to 20.6% less image noise compared to conventional CT images

Photon-counting CT image of the abdomen in 3D

Illustration shows that more than 500 scientific papers were published on photon-counting CT

The infographic shows that 54% of patients examined with photon-counting CT were spared invasive coronary angiography.

A one-stop imaging shop

Radiologists describe photon-counting CT as a new modality² that provides “impact beyond radiology” and envision “a photon-counting CT centric imaging approach.”² With its ability to provide high detail and efficiency, the technology will impact a wide range of medical fields, from oncology and cardiology to pediatrics and emergency care.

Where photon-counting CT is already essential in clinical routine

Photon-counting CT is set to improve patient outcomes and usher in a new era of precision medicine. Dive into the world of photon-counting and hear from key opinion leaders about how it delivers benefits across various clinical disciplines:

Improved visualization of fine brain structures

In neurology, photon-counting CT has improved the visualization of fine brain structures and subtle abnormalities through its high spatial resolution. It enhances diagnostic accuracy in detecting conditions like ischemic stroke and brain tumors, while reducing radiation exposure.²
“Up to 40 percent of all ischemic strokes are due to occlusions in the M2 or M3 vessels. With NAEOTOM Alpha, we can optimize the visibility of such small-sized arteries in the brain. This may expand the number of patients treated for their acute ischemic stroke.”
Pieter Jan van Doormaal, MD, Interventional and Neurointerventional Radiologist, Erasmus Medical Center, Rotterdam, The Netherlands

Precise tissue differentiation in oncology

In oncology, photon-counting CT enhances tumor detection and characterization through precise tissue differentiation. It enables detailed assessment of treatment response and reduces radiation exposure, which is particularly beneficial for patients who require frequent imaging.²
“We are seeing an improved tumor lesion depiction and detection of smaller parenchymal lesions, especially in difficult situations, such as in obese patients. This can give us more information on whether the therapies are effective or not.”
Professor Konstantin Nikolaou, MD, Head of Radiology, Diagnostic and Interventional Radiology, University Hospital Tübingen, Germany

High-resolution imaging of lung structures

In pulmonology, photon-counting CT provides high-resolution imaging of lung structures and subpleural structures, which enables precise detection of small nodules, and pulmonary vascular abnormalities. Experts have found that the technology’s ability to differentiate small lung structures and reduce radiation exposure makes it especially valuable for repeated imaging in chronic respiratory conditions [5, 6].

Detailed cardiac assessments

In cardiology, photon-counting CT offers ultra-high-resolution imaging of the coronary arteries, allowing for precise detection of plaques.² Experts have found that, by enhancing tissue characterization and reducing radiation dose, photon-counting CT is ideal for detailed cardiac assessments as well as follow-up imaging [7].
“Being able to image coronary stents and to see through coronary calcium better than ever before was very much part of the plan and thankfully has come to fruition for us.”
Conor Murray, MD, Principal Radiologist and CEO, ChestRad, Perth, Australia

Precision imaging for bone and soft-tissue insights

Photon-counting CT offers high spatial resolution and enhanced tissue contrast for visualizing complex musculoskeletal structures and cartilage. With metal artifact reduction and multi-energy imaging, it supports diagnostic accuracy for bone and soft tissue.
“I’ve never seen so detailed images in bone imaging. All our patients with bone questions will definitely go to photon-counting CT.”
Professor Dieter Szolar, MD, Diagnostikum Graz, Austria

Improved visualization of fine brain structures

In neurology, photon-counting CT has improved the visualization of fine brain structures and subtle abnormalities through its high spatial resolution. It enhances diagnostic accuracy in detecting conditions like ischemic stroke and brain tumors, while reducing radiation exposure.²
“Up to 40 percent of all ischemic strokes are due to occlusions in the M2 or M3 vessels. With NAEOTOM Alpha, we can optimize the visibility of such small-sized arteries in the brain. This may expand the number of patients treated for their acute ischemic stroke.”
Pieter Jan van Doormaal, MD, Interventional and Neurointerventional Radiologist, Erasmus Medical Center, Rotterdam, The Netherlands

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Already a gateway to the right treatment

The integration of photon-counting into routine CT imaging offers high image resolution and enhanced tissue characterization, with the NAEOTOM Alpha systems displaying anatomical details at 0.2-millimeter slice thickness. Combined with a temporal resolution of up to 66 milliseconds and reduced radiation dose in many cases, small abnormalities become visible. These features enable early, accurate diagnoses, personalized treatment planning, and improved monitoring. According to one study, “Patients who underwent PCD-CT [photon-counting detector CT] were less frequently referred to subsequent ICA [invasive coronary angiography] than those undergoing EID-CT [energy-integrating detector CT] [7].”

Professor Constantin von zur Mühlen³, MD, a cardiologist in the Department of Cardiology and Angiology at University Heart Center in Freiburg-Bad Krozingen, Germany, describes photon-counting CT as “the perfect method for quantifying calcification and for evaluating the amount of calcification or calcified stenosis.”

You can avoid an interventional procedure in these patients.
Professor Constantin von zur Mühlen, MD, Department of Cardiology and Angiology, University Heart Center in Freiburg-Bad Krozingen, Germany³

AI-driven workflows

With AI assistance integrated into all photon-counting CT systems, every step – from patient preparation to image acquisition, reconstruction, evaluation, and postprocessing – is seamlessly guided, thereby enhancing efficiency and accuracy. This streamlined workflow supports healthcare teams to consistently deliver high-quality results for various patient groups, procedures, or levels of operator experience. The impact is profound: Faster physicians’ diagnoses lead to quicker treatment initiation, offering the potential to improve outcomes, slow disease progression, and ease patients’ anxiety by supporting timely care delivery.

Rising precision: Photon-counting CT will define the future of imaging

Philipp Fischer, Head of CT at Siemens Healthineers, highlights the profound clinical impact that photon-counting CT is already having on patient pathways. He is confident that this technology will shape the future of CT imaging. As the medical field shifts from conventional CT to photon-counting systems, Fischer emphasizes the immense potential of this evolution. Photon-counting CT is not just a step forward – it is poised to revolutionize diagnostic capabilities, providing increasingly precise, efficient, and patient-friendly imaging solutions.

By Andrea Lutz

Andrea Lutz is a journalist and business trainer specialized on medical topics, technology, and healthcare IT. She lives in Nuremberg, Germany.

Disclaimers

¹NAEOTOM Alpha, NAEOTOM Alpha.Peak, NAEOTOM Alpha.Pro, and NAEOTOM Alpha.Prime are not commercially available in all countries. Their future availability cannot be guaranteed.

²Data on file.

³Professor Constantin von zur Mühlen, MD, is employed by an institution that receives financial support from Siemens Healthineers for collaborations.

The statements by customers of Siemens Healthineers described herein are based on results that were achieved in the customer's unique setting. Because there is no “typical” hospital or laboratory and many variables exist (e.g., hospital size, samples mix, case mix, level of IT and/or automation adoption) there can be no guarantee that other customers will achieve the same results.

References

[1] Cademartiri F. INSIGHT INTO PHOTON COUNTING CT TECHNOLOGY. Available from https://www.linkedin.com/posts/filippocademartiri_pcct-photoncounting-quantumhd-activity-7232677930269646848-8Bd1?utm_source=share&utm_medium=member_desktop. Last accessed Feb 3, 2025.

[2] Hagar MT, Soschynski M, Saffar R, Rau A, Taron J, Weiss J, et al. Accuracy of ultrahigh-resolution photon-counting CT for detecting coronary artery disease in a high-risk population. Radiology [Internet]. 2023;307(5).

[3] Madhavan AA, Yu L, Brinjikji W, Cutsforth-Gregory JK, Schwartz FR, Mark IT, et al. Utility of photon-counting detector CT myelography for the detection of CSF-venous fistulas. AJNR Am J Neuroradiol [Internet]. 2023;44(6):740–4.

[4] Pourmorteza A, Symons R, Reich DS, Bagheri M, Cork TE, Kappler S, et al. Photon-counting CT of the brain: In vivo human results and image-quality assessment. AJNR Am J Neuroradiol [Internet]. 2017;38(12):2257–63.

[5] Aurumskjöld M-L, Sjunnesson L, Pistea A, Ásbjörnsson G, Wellman F, Bozovic G. A new era of high-resolution CT diagnostics of the lung: improved image quality, detailed morphology, and reduced radiation dose with high-resolution photon-counting CT of the lungs compared to high-resolution energy-integrated CT. Acta Radiol. 2024;65(10):1211–1221.

[6] Graafen D, Halfmann MC, Emrich T, Yang Y, Kreuter M, Düber C, et al. Optimization of the reconstruction settings for low-dose ultra-high-resolution photon-counting detector CT of the lungs. Diagnostics (Basel) [Internet]. 2023;13(23).

[7] Sakai K, Shin D, Singh M, Malik S, Dakroub A, Sami Z, et al. Diagnostic performance and clinical impact of photon-counting detector computed tomography in coronary artery disease. J Am Coll Cardiol. 2025;85(4):339–348.