American College of Radiology Dose Index Registry: A User's Guide for Cardiothoracic Radiologists Part 1: Dose Index Registry (DIR)-What it Means and Does for CT?

Computed tomography (CT) is an indispensable part of diagnostic imaging and contributes significantly to patient care. With increasing use of CT, there have been growing concerns regarding risks from radiation exposure. This has prompted efforts to introduce measures to optimize the radiation dose used in CT imaging. The Dose Index Registry (DIR) was launched by the American College of Radiology (ACR) in 2011. It provides a national database of radiation dose indices for various CT examinations performed at participating institutions. It affords an opportunity for institutions to compare and tailor their CT protocols against existing national averages. In this article, we review the history, mechanism, and major elements of the DIR. We also briefly discuss similar radiation dose registries in other countries.