Influence of tube voltage on image quality in non-contrast photon-counting computed tomography of the head: Comparison of 120 kVp and 140 kVp

Purpose Non-contrast cerebral computed tomography (NCCT) is one of the most frequently performed CT examinations. Photon-counting CT (PCCT) offers advantages in terms of noise reduction, higher spatial resolution, and inherent spectral information. PCCT available today allows NCCT to be performed with tube voltage of 120 or 140 kVp. This study evaluates the impact of tube voltage on image quality at an equivalent dose. Methods 76 patients with an NCCT with 120 kVp, 76 with 140 kVp, and 56 patients with slightly different effective tube current per group were included. Signal, noise, signal-to-noise ratio, gray-white contrast, and contrast-to-noise ratio were determined using several regions of interest for different virtual monoenergetic image (VMI) levels and compared between dose-equivalent groups. An image quality rating of the clinically used virtual monoenergetic images (VMIs) 65 keV was performed. Results The VMI 65 keV images at 120 kVp exhibited reduced noise, improved gray-white contrast, and improved contrast-to-noise ratio compared to 140 kVp (p < .001). The density differences between cortical gray matter at different distances from calvaria were also lower with 120 kVp (p < .001). The rating of image quality showed no difference between 120 kVp and 140 kVp. Conclusions Currently, NCCT with a tube voltage of 120 kVp versus 140 kVp seems to achieve better image quality. However, further studies are required to evaluate possible advantages of 140 kVp, for example artifact reduction in the case of dense foreign materials or enhanced spectral possibilities, and regarding imaging of special intracranial pathologies.