Strategies and Scientific Basis of Dose Reduction on State-of-the-Art Multirow Detector X-Ray CT Systems.

Abstract

The continued development in multirow detector computed tomography (MDCT) technology accompanied by tremendous enhancement in the clinical utility and rapid increase in the number of MDCT scanners worldwide are causing a steep rise in the number of diagnostic computed tomography (CT) procedures performed each year. The everincreasing use of this X-radiation-based imaging technique has raised radiation protection concerns among the clinical community and general public. To address these concerns, significant efforts have been made by the clinical community as well as industry, research, and government organizations. Because of these efforts, modern MDCT systems are now equipped with a variety of tools that can lead to "radiation dose-optimized" CT images if used properly. This review describes CT dose metrics and their limitations, radiation dose reduction techniques and strategies implemented using modern MDCT scanners, and the role of research and regulatory organizations in developing guidelines and regulations to facilitate the adoption of the dose reduction strategies. An account of further developments required to achieve submillisievert X-ray CT doses and to make X-ray CT a radiation risk-free imaging modality is also given. A detailed description of the scientific basis and controversies surrounding the linear no threshold (LNT) model, which forms the basis of all radiation dose reduction strategies, is also provided in this review. According to the LNT model, there is no amount of radiation that is safe or beneficial for human beings. Based on recent epidemiological studies, despite all of the controversies, the LNT model continues to be the basis of the ALARA (as low as reasonably achievable) principle of radiation protection framework in CT.