"It has the potential for better contrast and noise performance compared to scintillator-based energy integration detector [CT]," presenter Richard Thompson, PhD, of Canon Medical Research Institute USA in Vernon Hills, IL, told session attendees.

Thompson and colleagues conducted a study using a phantom to compare image quality between a prototype photon-counting CT device and a conventional CT system, analyzing for noise, spatial resolution, and accuracy.

The photon-counting prototype was based on a Canon Aquilion One Vision system. Its smallest detector pixel size is 342 µm; each pixel produces measurements of up to six energy bins starting from 20 keV, Thompson said. (Photon-counting detectors generate energy-specific images that are assigned to energy bins in small ranges.)

The investigators scanned a 40-cm water phantom and Sun Nuclear's Gammex multienergy phantom with both the photon-counting prototype and the conventional scanner, comparing both counting and spectral images. The photon-counting CT device produced images with 20% to 25% reduced noise compared to conventional CT and had higher spatial resolution, from 0.60 lp/mm for conventional CT to 0.69 lp/mm for the photon-counting device.

"The initial performance of this prototype photon-counting CT system in both counting and spectral imaging modes demonstrates its potential to achieve better diagnostic performance with reduced dose," Thompson concluded.