3D automatic exposure control for 64-detector row CT: Radiation dose reduction in chest phantom study

Purpose

The purpose of this study was to determine the utility of three-dimensional (3D) automatic exposure control (AEC) for low-dose CT examination in a chest phantom study.

Materials and methods

A chest CT phantom including simulated focal ground-glass opacities (GGOs) and nodules was scanned with a 64-detector row CT with and without AEC. Performance of 3D AEC included changing targeted standard deviations (SDs) of image noise from scout view. To determine the appropriate targeted SD number for identification, the capability of overall identification with the CT protocol adapted to each of the targeted SDs was compared with that obtained with CT without AEC by means of receiver operating characteristic analysis.

Results

When targeted SD values equal to or higher than 250 were used, areas under the curve (Azs) of nodule identification with CT protocol using AEC were significantly smaller than that for CT protocol without AEC (p < 0.05). When targeted SD numbers at equal to or more than 180 were adapted, Azs of CT protocol with AEC had significantly smaller than that without AEC (p < 0.05).

Conclusion

This phantom study shows 3D AEC is useful for low-dose lung CT examination, and can reduce the radiation dose while maintaining good identification capability and good image quality.