Paranasal sinuses: low-dose CT.

While computed tomography (CT) has become an important imaging modality in the evaluation of the paranasal sinuses, the radiation dose remains higher than is necessary. With use of a head phantom and constant kilovolt peak setting, axial and coronal CT scans of the paranasal sinuses were obtained at each of six successively lower milliampere second settings than are commonly used in clinical practice. Although noise, as measured by the standard deviation of the CT numbers, did increase, images were of diagnostic quality even when dose levels were reduced by a factor of 28. In the same incremental manner, the milliampere second settings used in scanning 90 patients were reduced, with no loss of diagnostic quality. The authors discuss the methods of analysis and the advantages of use of lower milliampere second settings at CT scanning of the sinuses.