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

Purpose. To compare low-dose protocols using either reduction of the rension (kV) or reduction of the intensity (mAs) at abdominal CT imaging, with reference to image quality. Materials and Methods. Fifty adult patients, weighing less than 55kg, were prospectively included among patients referred for abdominal CT examination when the protocol required a noncontrast study. The images obtained with the standard protocol (120kV, 200mAs) were compared to 4 additional test images, two obtained with low intensity (120kV, 100mAs) and two obtained with low tension (100kV, 200mAs). 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). Results. 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. Conclusion. 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.