For the study, the researchers analysed the technical performance of a dual-source PCD-CT system for standard and high-resolution collimations
The first clinical photon-counting-detector (PCD) CT system available for patient care outperforms current state-of-the-art CT systems, according to a new study published in the journal Radiology.
PCD-CT systems have shown several advantages over standard CT, including suppression of electronic noise, improved spatial resolution, and reduced radiation dose. PCDs directly convert x-rays to electrical signal, facilitating small detector pixel designs without loss of geometric dose efficiency and allowing simultaneous multi-energy CT through the use of multiple energy thresholds.
Advances in the detector technology have facilitated translation of PCDs to human imaging at clinical doses and dose rates, demonstrating potential clinical benefits for patients. With the introduction of the first clinical PCD-CT, the beneficial characteristics of PCDs can be realised in clinical practice. However, a comprehensive performance assessment is needed to confirm current clinical requirements are met and to provide performance benchmarks.
Cynthia McCollough, Ph.D., and colleagues from the Department of Radiology at the Mayo Clinic in Rochester, Minnesota—working with representatives from Siemens Healthineers in Forchheim, Germany, and Siemens Medical Solutions in Malvern, Pennsylvania—set out to assess the technical performance of a clinical PCD-CT.
Dr McCollough, director of Mayo Clinic’s CT Clinical Innovation Center said, “PCD-CT is so exciting because it provides information that existing CT detectors – the types that we’ve used for over 50 years – previously just couldn’t capture. 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.”
For the study, the researchers analysed the technical performance of a dual-source PCD-CT system for standard and high-resolution collimations. Noise power spectrum, modulation transfer function, section sensitivity profile, iodine CT number accuracy in virtual monoenergetic images, and iodine concentration accuracy were measured.
Four participants were enrolled between May 2021 and August 2021 in this prospective study and scanned using similar or lower radiation doses compared to same-day exams performed using energy-integrating-detector (EID) CT. Four clinical indications (CT angiography of the coronary arteries and abdomen/pelvis, whole-body low-dose CT for skeletal surveillance, and temporal bone imaging) were selected to illustrate in humans the effects of PCD-CT’s improved technical performance in phantoms. PCD-CT scans were performed at the same or lower radiation dose relative to the clinical exam. The results showed that PCD-CT demonstrated superior spatial resolution relative to current CT systems and improved noise properties and multi-energy temporal resolution relative to similarly configured EID-CT.
The high-resolution mode of the PCD-CT demonstrated 125-micron in-plane spatial resolution and 0.3 mm longitudinal resolution, the smallest reported to date for a clinical CT system. The PCD-CT system provided 66-ms temporal resolution multi-energy imaging in dual source mode. Noise reduction (up to 47 per cent) or dose reduction (up to 30 per cent) were achieved in study participants using the PCD-CT system relative to a similar CT system equipped with conventional detectors.