AAPM/RSNA physics tutorial for residents: Technologic advances in multidetector CT with a focus on cardiac imaging

Cardiac computed tomography (CT) is emerging as an important tool for the diagnosis and monitoring of heart disease. The prevalence of heart disease in the United States is already quite high and is expected to increase as the "baby boomer" segment of the population ages. To use complex multiple-row detector CT scanners most efficiently for cardiac examinations, it is important to understand many of the technical components. New developments in CT technology provide the ability to examine the structure of the heart with a level of detail that was not previously possible. In general, detector configurations have improved, the number of channels has increased, and rotation speed has increased, resulting in better quality of cardiac images. However, radiation dose for cardiac CT is fairly high and demands constant vigilance. Several steps can be taken to reduce the dose, including lowering the tube current as the x-ray beam crosses over certain areas of the body, decreasing the tube current during certain phases of the cardiac cycle, and using a higher pitch. Cardiac CT examination dose (for a coronary artery study) is approximately equivalent to that of an abdominal-pelvic CT examination or a dual-phase chest CT examination.