The effect of mAs variation upon computed tomography image quality as evaluated by in vivo and in vitro studies.

Abstract

The effect of different mA settings on computed tomography (CT) image quality was evaluated by a human study and phantom studies. In the clinical portion of this study, a number of CT images, obtained at various mA settings, were reviewed by experienced CT interpreters. From these same images, graphs were charted of the root-mean SD (RMSD) vs. body size; there appeared to be a linear relationship between noise, as measured by RMSD, and body size. A performance phantom was used to evaluate the effect of the different mA settings on resolution. There was some loss in low contrast resolution at 6 and 20 mA; however, the resolution was identical at 40 and 100 mA.