The radical question about photon-counting CT: can we afford not to use it?
Since the first photon-counting CT system received FDA clearance in 2021, the technology has begun to demonstrate its potential in clinical practice. The technology captures greater detail from each examination, supporting greater diagnostic confidence where conventional CT may leave questions unresolved. The FDA described it as the first major new CT imaging technology in nearly a decade.[1] Cardiovascular imaging has already shown how coronary CT angiography can inform referrals to the catheterisation laboratory and support revascularisation planning. The next frontier is to understand what this could mean for spectral imaging across clinical pathways.
But greater capability brings a practical challenge. Photon-counting CT can generate a wealth of spectral and quantitative information alongside conventional CT images. At a time when many radiologists already have too little time, how can services make use of that additional information without creating additional work? With demand rising, workforce shortages continuing and reporting backlogs placing services under sustained pressure, concern about the workload associated with spectral imaging is entirely reasonable.
Yet reporting time alone may be the wrong measure of efficiency. If spectral information helps resolve diagnostic uncertainty during the initial CT examination, the work has not necessarily been added to the patient pathway. It may simply have been moved upstream. Radiology has adapted to increasing volumes and complexity of information before. MRI is perhaps the most obvious comparison. Diffusion-weighted imaging, once routinely associated with head imaging, is now used much more widely, including in oncological imaging and surveillance. As diffusion, perfusion and multiparametric techniques expanded the information available to radiologists, expertise, workflows and clinical applications evolved alongside them.
Spectral CT presents a different implementation challenge because many of its capabilities arrive at the same time. MRI accumulated new sequences gradually, allowing radiologists to absorb additional information into clinical practice over time. With spectral CT, the change can feel much more immediate. Alongside conventional CT images, an examination may provide monoenergetic images, iodine maps, virtual non-contrast images and other spectral or quantitative information at once. For radiologists already facing significant reporting pressures, it is reasonable to ask whether there is realistically time to review all of this. That is not resistance to innovation. It is a practical response to the significant resource and workforce challenges facing radiology services. However, we should also consider where the alternative work takes place.
Diagnostic uncertainty following CT may lead to an additional CT phase, an ultrasound or MRI examination, interval surveillance, or further discussion at a multidisciplinary team meeting. Each additional step consumes time and resources across the healthcare system. It also consumes something we perhaps discuss less often: the patient’s time. Perhaps the most efficient pathway is one in which the first CT provides a conclusive answer, avoiding further scans, reports and delays for the patient.
Spectral information creates an opportunity to answer some of these questions during the initial CT consultation. Interrogating that information may require a little more time during reporting. Yet, if it increases diagnostic confidence and avoids a subsequent investigation and report, that time has not simply been added to the pathway. It has been invested earlier to remove work later.
This raises a broader question about how we measure productivity. If an additional minute spent reviewing spectral information helps avoid a follow-up examination and report, should the CT examination be considered less efficient? Or should efficiency also reflect how much uncertainty has been removed and how quickly the patient can move to the next appropriate stage of care?
Of course, the answer cannot simply be to give radiologists more images to review. The clinical value of spectral information and the workflow through which it is accessed are two separate considerations.
Historically, advanced post-processing has often required radiologists to leave their primary reporting environment, open another application or complete additional steps to retrieve the information they need. In a pressured service, even relatively small interruptions can become barriers to routine use. That is beginning to change as spectral tools are increasingly incorporated into the environments radiologists already use. This will be crucial as the adoption of photon-counting CT broadens.
The goal should not be to present every possible spectral reconstruction from every examination. It should be to surface the right information, at the right time, for the clinical question being asked. The future is not more images. It is more actionable information, delivered within the workflow.
There is also much to learn from the NHS departments already pioneering photon-counting CT. Their experience can help the wider radiology community understand where spectral information genuinely influences clinical decisions, which protocols and pathways may need to be redesigned, and where additional acquisitions or downstream investigations might be avoided.
This is not a challenge for radiologists alone. Radiographers have a crucial role in protocol design and optimisation, working alongside radiologists, medical physicists and the wider multidisciplinary team. Maximising the potential of photon-counting CT will require those groups to consider not only how an examination is acquired, but how the information it provides can support decisions across the patient pathway.
Training will be equally important. Making spectral information available does not automatically make it useful. Teams need the confidence to recognise when it may add value, understand which reconstruction is relevant to the clinical question and know when conventional imaging already provides the answer.
The workforce pressures facing UK radiology make caution understandable. But they also make it more important to evaluate innovation across the whole patient pathway, rather than solely by its immediate impact at the reporting workstation.
The challenge is not simply whether photon-counting CT can provide useful information. It is how to create the workflows, training and clinical pathways that allow radiology teams to turn that information into earlier, more confident decisions.
Radiology cannot assess spectral imaging solely by the time it adds at the reporting workstation. In an NHS under increasing pressure, the more radical question is this: can we afford not to use the information we already have?
References
[1] PR Newswire; ‘FDA Clears First Major Imaging Device Advancement for Computed Tomography in Nearly a Decade’ [2021]. Available from: https://www.prnewswire.com/news-releases/fda-clears-first-major-imaging-device-advancement-for-computed-tomography-in-nearly-a-decade-301389131.html
Further information on the topic of photon-counting CT can be found here.
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