The first photon-counting detector CT to be used in a clinical capacity has outperformed current state-of-the-art CT systems, demonstrating several advantages that can now be realized in clinical settings.

Unlike standard CT, PCD-CT systems can suppress electronic noise, improve spatial resolution and reduce radiation dose. Its main difference is that it measures each individual X-ray that passes through a patient’s body. By "counting" each individual X-ray photon, the scanner can collect more detailed information about the patient and form images that reflect the most useful information for diagnosis and treatment, and personalize care.

With advances in detector technology, such scanners can be used to image humans at clinical doses and dose rates. Still, a comprehensive performance assessment must confirm clinical requirements are met and show performance benchmarks. To assess its technical performance in a clinical setting, the radiology department at Mayo Clinic teamed up with Siemens Healthineers, which owns the system under evaluation, and Siemens Medical Solutions in Pennsylvania.
The researchers evaluated the dual-source PCD-CT system for standard and high-resolution collimations on four patients who were also imaged the same day with energy-integrating detector CT. The dose in both scans was the same or lower relative to the clinical exam. The clinical indications assessed included CT angiography of the coronary arteries and abdomen/pelvis, whole-body low-dose CT for skeletal surveillance and temporal bone imaging.

PCD-CT had better spatial resolution, improved noise properties, and multi-energy temporal resolution. The high-resolution mode was 125-micron in-plane spatial resolution and 0.3 mm longitudinal resolution, the smallest reported to date for a clinical CT. It also provided 66-ms temporal resolution multi-energy imaging in dual source mode, reduced noise by up to 47%, and dose by up to 30% in study participants, compared to a similar CT system equipped with conventional detectors.

"It allows us to scan faster, with lower radiation and contrast media doses, while obtaining higher quality images with greater spatial detail and lower noise levels. For many clinical applications, the improvements in image quality are really striking,” said Dr. Cynthia McCollough, director of Mayo Clinic's CT Clinical Innovation Center, in a statement.

She adds that in addition to enhancing resolution and providing new information and insights, the use of PCD-CT could potentially expand the pool of candidates eligible for a broad range of exams. “In patients with coronary artery disease, for example, PCD-CT can provide diagnostic quality images in patients who previously were not good candidates for CT imaging of their coronary arteries. This will spare many patients from having to have more invasive types of testing.”

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