Introduction
The radiation risk of computed tomography (CT) is well known in the radiological community, although the continuous development of new scanners with greater temporal and spatial resolution sometimes leads to an abuse of CT. The excellent image quality, beautiful 3D reconstructions and important clinical utility have made the request for CT examinations increase enormously all over the world, especially in western countries. In Europe, there is a balanced use of all imaging modalities and a widespread use of ultrasonography (US), which in most cases reduces or limits the requests for CT. Nevertheless, new applications for CT, such as angiography, coronary angiography and colonography, and vast use in the emergency room have led to a significant increase in the number of CT exams.