The rapid technological development within CT has resulted in a continuing expansion of CT examinations. Due to the high radiation dose often delivered by CT it is important to ensure that the required diagnostic information is achieved with minimum dose to the patient. The European Guidelines on Quality Criteria for CT includes anatomical/diagnostic image quality criteria for six main groups of examinations: cranium, face and neck, spine, chest, abdomen and pelvis, and bones and joints. The clinical use of such criteria has been limited and a pilot multicentre study has therefore been performed with regard to their utility in clinical practice for five types of examinations: (1) face and sinuses, (2) vertebral trauma, (3) HRCT of the lung, (4) liver and spleen, and (5) osseous pelvis. The results show that the diagnostic criteria can be used to optimise CT procedures to achieve doses that are as low as consistent with required diagnostic image quality.