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

Radiology. 1981 Feb;138(2):449-54. doi: 10.1148/radiology.138.2.7455129.


The effect of different mAs settings on computed tomobraphy (CT) image quality was evaluated by a clinical study and phantom studies. In the clinical portion of this study, a number of CT images, obtained at various mAs settings, were reviewed by experienced CT interpreters. From these same images, graphs were charted of the root-mean-standard deviation (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 mAs settings on resolution. There was some loss in low contrast resolution at 6 and 20 mAs; however, the resolution was identical at 40 and 100 mAs.

MeSH terms

  • Humans
  • In Vitro Techniques
  • Models, Structural
  • Pancreas / diagnostic imaging
  • Radiation Dosage*
  • Radiographic Image Enhancement / methods*
  • Tomography, X-Ray Computed / methods*