[Dose reduction at abdominal CT imaging: reduced tension (kV) or reduced intensity (mAs)?]

To compare low-dose protocols using either reduction of the tension (kV) or reduction of the intensity (mAs) at abdominal CT imaging, with reference to image quality.

Fifty adult patients, weighing less than 55 kg, were prospectively included among patients referred for abdominal CT examination when the protocol required a noncontrast study. The images obtained with the standard protocol (120 kV, 200 mAs) were compared to 4 additional test images, two obtained with low intensity (120 kV, 100 mAs) and two obtained with low tension (100 kV, 200 mAs). Two senior radiologists blindly reviewed all images using both subjective (itemized list) and objective criteria (measure of standard deviation for density measurements obtained of the liver parenchyma).

The image quality of the low kV protocol was better than the image quality of the low mAs protocol for both subjective and objective criteria.

For abdominal CT imaging of standard to thin adult patients or children, dose reduction using a low kV protocol may be an alternative to a protocol using a low intensity. This can easily be implemented and can be used in conjunction with a dose reducing software.