Spectral photon-counting CT: The next revolution in computed tomography (CT) imaging [1]

Photon-counting detector CT technology, in particular, offers the potential to transform patient care by improving diagnostic accuracy through ultra-high-resolution CT imaging, supporting enhanced spectral capabilities, including k-edge imaging, in every CT scan. This allows scans with more than two energy levels. This advance beyond dual-energy CT offers the opportunity to lower radiation dose, minimizing patient risk associated with high and frequent radiation exposure. Current CT system designs encounter challenges in fulfilling the promises of this new technology. Clinicians search for high image quality without electronic noise, dose efficiency and fast image reconstruction. Issues remain with managing various patient protocols and complex workflows, processing large data sets, and the lack of AI integration. These challenges must be overcome if photon-counting CT is able to reach its true potential. At Philips, we are advancing spectral photon-counting CT (SPCCT) together with the University of Lyon to evaluate the clinical impact of this approach to photon-counting computed tomography. In addition, our goal is to expand the clinical implementation of SPCCT to a broader patient population. By combining AI, photon-counting detector technology and enhanced spectral capabilities, SPCCT may enhance the benefits of medical imaging, including enhanced spectral cardiac assessment, lesion detection and tissue characterization. This has positive implications for a range of conditions, including coronary artery disease. With easy-to-manage workflow and smart data management SPCCT may finally bring spectral photon counting into routine clinical use, helping clinicians leverage medical imaging to provide better care for more people.

When each photon’s energy is identified, spectral analysis and material differentiation can be provided in every scan. [2] What differentiates spectral photon-counting CT from current energy-integrating detector (EID) technology is the detector design and detection material. Spectral photon-counting CT uses advanced semiconductor detectors, typically made from cadmium-based material such as cadmium zinc telluride (CZT), to directly convert incoming X-ray photons into electrical signals per photon. [3] Unlike conventional computed tomography detectors that integrate energy, photon-counting detector CT can measure the energy of each individual photon, producing rich spectral data for every scan. The result:

Photon-counting CT offers enhanced clinical benefits across multiple specialties [4]:

When implementing new technology, it is essential that its benefits be capable of reaching all patients. Combining features such as ultra-high resolution, full coverage and radiation dose reduction across all protocols is particularly important, as this combination allows fast, artifact-free exams--especially in time-critical areas such as cardiac imaging. Data volume and workflow complexity may also limit routine use. Currently, photon-counting systems generate a great deal of data. Due to inherent small detector elements of a photon-counting CT system, resulting in smaller slice thicknesses and increased spatial resolution, it is estimated that data size increases dramatically. The sizeable amount of data generated by these scanners, which includes larger matrix size ultra-high-resolution images and spectrally derived images, will require improvements in data storage, interpretation and radiology workflow management. We believe imaging technology must be intuitive and practical to become part of the clinical routine. Advances in photon counting CT detectors must be designed to meet today’s real-world challenges, such as staffing shortages and budget limits, without sacrificing quality or care.

Philips was first to market [6] with a detector-based spectral CT system, redefining what’s possible in dual-energy CT imaging.

Building on this heritage, Philips is now advancing SPCCT technology through major research collaborations, including:

In partnership with the University of Lyon, France, we are advancing this technology to make photon-counting CT accessible for a broad range of patient types. With our clinical prototype with AI-powered reconstruction [7] already installed, we are developing the next-generation CT Smart Spectral Workflow. This is designed to support the integration of photon-counting capabilities into everyday clinical practice. In addition, we are collaborating with leading academic centers across Europe through EU-funded studies [3] that investigate and validate the clinical applications of photon-counting technology. Our focus is on enabling simultaneous photon-counting capabilities that may benefit a broad range of patients and clinical scenarios.

At the end of the day, what truly matters is improving patient outcomes and delivering better care for more people. While we continue developing our next-generation technology to further enhance patient benefits, we are committed to delivering meaningful advantages today through the power of spectral imaging and AI. This is where Verida* Spectral CT is making a difference and delivering on the promise of photon counting today.

Advances in AI are transforming every stage of the imaging process from intelligent image reconstruction and workflow support to powerful diagnostic analytics. By combining the precision of spectral technology with the power of AI, Philips is expanding what CT imaging can offer clinicians and their patients. AI-powered reconstruction [7] lies at the core of Philips Verida* spectral CT system, enhancing both the CT detector data and spectral information to support clinicians in delivering better care. Patients can benefit from faster, high-quality CT scans when time and clarity are critical. Enhanced detail and functional insights help radiologists use medical imaging to provide timely diagnoses. Verida* supports the entire end-to-end workflow, from acquisition to interpretation to data storage, making it ideal for high-throughput environments like ED/trauma, and for stroke and cardiac cases, where speed and precision are critical. Because at the end of the day, what matters most is patient care.