AJR:195, September 2010
Charles S.White
Medical imaging has increased dramatically over the past two decades and with it the cumulative radiation dose to the population. Much of this increased dose has been attributed to the proliferation of CT [1]. Despite a low volume compared with CT of many other parts of the body, coronary CT angiography (CTA) has become the poster child for examinations perceived to have excessive radiation exposure. This sentiment is partly justified because several studies have indicated that coronary CTA can produce dose numbers higher than most other CT examinations, although unlike many parts of the body, competing or complementary car-diac tests often produce doses that are as high or higher. Concerns surrounding the potentially harmful impact of CT in general and coronary CTA in particular have led to numerous strategies to decrease the dose, including automatic exposure control, low kVp settings, ECG-triggered current modulation, prospective ECG-triggering, noise reduction filters, and bismuth breast shielding.