Low-contrast detectability of a mobile head CT compared with conventional CT

To investigate the image quality of a newly introduced mobile head CT system in comparison with a modern stationary CT scanner, emphasizing low-contrast detectability pertinent to brain imaging.

The Siemens On.site mobile head CT system has been compared with the conventional Siemens X.ceed scanner under matching imaging conditions. Measures of spatial resolution (TTF), noise (NPS), and noise equivalent quanta (NEQ), along with low-contrast detectability in terms of the spatial-domain channelized Hotelling observer, have been assessed. These quantitative evaluations were performed by scanning the Catphan 191 (head) MITA phantom using typical head CT imaging settings. This phantom, which is about the size of an adult head, contains a uniform section to measure noise, and a section with cylindrical features of varying diameters (2-15 mm) and contrasts (3-9 HU) to measure resolution and low-contrast detectability. Statistical significance was tested with a paired two-sample t-test.

The two scanners exhibited similar spatial resolution. However, the mobile head CT was associated with less noise, thereby improving the NEQ by approximately 10%, suggesting a higher efficiency of scanner dose utilization. In terms of low contrast detectability, the mobile head CT performed better by 5%-34%, depending on the size of the feature, its contrast, and whether iterative reconstruction was used or not. This improvement was found to be statistically significant (p-value less than 0.02).

The On.site mobile head CT system represents progress in mobile scanning technology, providing low-contrast detectability that is non-inferior compared with modern stationary CT scanners.