RT Book, Section A1 Nieman, Koen A2 Samady, Habib A2 Fearon, William F. A2 Yeung, Alan C. A2 King III, Spencer B. SR Print(0) ID 1146596028 T1 Computed Tomography of the Coronary Arteries T2 Interventional Cardiology, 2e YR 2017 FD 2017 PB McGraw-Hill Education PP New York, NY SN 9780071820363 LK accesscardiology.mhmedical.com/content.aspx?aid=1146596028 RD 2024/03/29 AB Computed tomography (CT) was developed in the early 1970s. The first computed axial tomography (CAT) scanners developed by Sir Geoffrey Hounsfield and colleagues required long acquisition and reconstruction times and were only suited for (small) stationary body parts like the head (Fig. 12-1). However, within the same decade, scanners dedicated to cardiac imaging were developed that were able to acquire images in 100 milliseconds or less, which was sufficient to virtually freeze cardiac motion. Contrary to mechanical CT scanners, these electron-beam CT systems lacked mechanically rotating parts. Instead of a rotating tube-detector unit, a beam of electrons was electromagnetically swept along a stationary tungsten target ring around the patient. As the electrons hit the tungsten ring, a roentgen fan beam was created. On the opposite side of the gantry, attenuated roentgen rays were collected by a stationary ring of roentgen detectors. For over 2 decades, these scanners were in operation, primarily to image coronary calcium,1 but also to image the coronary lumen after intravenous contrast injection.2 Technical and other practical challenges to electron-beam CT, such as difficulties expanding the number of simultaneously acquired slices and expanding the longitudinal scan range, stalled further exploitation.