Photon-Counting CT in the Emergency Department: Practical Impact in a High-Volume Setting

Emergency departments continue to face increasing imaging volumes and growing pressure to deliver rapid, confident diagnoses on the first scan. In that environment, new CT technologies must demonstrate practical value, not only in image quality, but in workflow efficiency and diagnostic confidence.

Recently, Applied Radiology sat down with Aaron Sodickson, MD, PhD, Associate Professor of Radiology at Harvard Medical School, and Division Chief of Emergency Radiology at Mass General Brigham, to discuss how photon-counting CT (PCCT) is being used in a busy emergency department and where it is beginning to make a meaningful difference in daily practice. The conversation was hosted by Applied Radiology Group Publisher Kieran Anderson.

Early Experience with PCCT in the ED

Dr. Sodickson noted that his department installed a photon-counting CT scanner in the emergency department approximately two years ago and has since incorporated it into routine use across the ED population. From his perspective, PCCT is no longer an experimental tool but part of standard emergency imaging workflows.

“We’ve been using it routinely on all of our ER patients,” he said, citing several immediate benefits, including reduced radiation dose, higher spatial resolution, and access to spectral information. Musculoskeletal imaging has stood out for its unprecedented high spatial resolution, with Dr. Sodickson describing the image quality as “gorgeous,” especially for evaluating small fractures and fine bony detail.

According to Dr. Sodickson, the improved spatial resolution of PCCT reveals detail that conventional CT can’t, which can change surgical management. For example, in the peripheral extremities, ”we use ultra-high-resolution mode 0.2 mm images with very sharp kernels for exquisite visualization of fine trabecular details and use 0.4 mm images for the larger extremities—shoulders, hips through knees. With this resolution, we have found nondisplaced fractures that are nearly invisible on more conventional slice thicknesses and are better able to visualize nondisplaced fracture extension to adjacent joints,” he said.

Spectral Information as a Routine Part of Interpretation

One of the more substantive shifts Dr. Sodickson described is how spectral information is used with photon-counting CT. Rather than treating spectral or dual-energy data as an optional add-on, his department has integrated spectral processing into routine interpretation.

“We’re inherently using spectral processing for everything that we do,” he explained. By standardizing image reconstructions using kiloelectron volt (keV) images rather than traditional kVp-based images, the department has achieved greater consistency in image appearance across studies.

In practical terms, this allows radiologists to tailor interpretation to the clinical question without changing acquisition protocols. With pulmonary embolism imaging, for example, low-keV images enhance vascular contrast, while higher-keV images can be used to better evaluate surrounding soft tissues.

By making spectral information easier to access and to incorporate into everyday CT interpretation, PCCT can address some of the workflow and usability barriers that previously limited consistent use of spectral and dual-energy CT techniques in routine practice, Dr. Sodickson noted.

Reducing Repeat Imaging in Time-Sensitive Scenarios

Operational efficiency is especially critical in emergency imaging, and Dr. Sodickson highlighted pulmonary embolism CT angiography as a clear example of where PCCT has changed practice. Historically, inadequate contrast opacification has led to a non-trivial rate of repeat scans.

“With photon-counting CT,” he said, “that failure rate has essentially gone away.” Optimized contrast timing combined with low-keV reconstructions has significantly reduced the need for repeat imaging. Beyond vascular imaging, spectral information can also reduce the need for delayed or follow-up scans in other settings, he notes. In CT of the head, for example, spectral techniques can help distinguish calcification from hemorrhage on the initial exam, allowing more definitive interpretation without additional imaging.

For pulmonary embolus CT, the ED had been averaging a 2-3% repeat injection rate across multiple scanners with optimized contrast infusions. Adding PCCT contrast infusion and 40 keV reconstructions to the protocol, “that repeat injection rate has fallen to a small fraction of a percent,” said Dr. Sodickson.

Managing Incidental Findings More Confidently

Incidental findings are common in emergency CT and frequently drive downstream testing. Dr. Sodickson emphasized that improved tissue characterization with PCCT can help mitigate this issue. “If we can characterize lesions more completely when we first find them,” he said, “we can avoid a lot of downstream testing.”

A significant example is the reduction of imaging recommendations for incidental renal lesions that measure higher than simple fluid attenuation on conventional CT. These findings trigger a large percentage of follow-up imaging with renal mass protocol CT or MRI to differentiate enhancing masses from benign non-enhancing hemorrhagic or proteinaceous cysts. Dr. Sodickson said “improvements in iodine characterization enabled by PCCT allows us to definitively characterize many more of these lesions as benign than we could on previous dual-energy systems, and to avoid follow-up imaging recommendations in many more of these cases.”

Where PCCT Fits Today

While photon-counting CT remains early in its broader adoption, Dr. Sodickson’s experience suggests that its value in the emergency department extends well beyond improved image quality. By combining higher spatial resolution, routine spectral information, and fewer nondiagnostic studies, PCCT is beginning to influence how emergency CT imaging is performed and interpreted.