ANATOMICALLY ADAPTED VARIATION OF THE TUBE CURRENT IN CT - STUDIES ON REDUCTION OF RADIATION-DOSE AND IMAGE QUALITY

Purpose: To assess the impact of a method for anatomically adapted tube current variation. The resulting CT image quality was evaluated quantitatively and qualitatively. Methods: CT scans of 100 patients were performed with a constant tube current (Group 1) and another 100 patients with an anatomically adapted tube current (Group 2). The CT tube current was varied during a 360 degrees tube rotation reflecting the measured density values extracted from two perpendicular scout views. The standard deviation of densities of defined regions was measured. The image quality was ranked (1 = non-diagnostic-5 = excellent) by three radiologists. Results: The effective tube current could be reduced by an average of 8.9% (0-20.4%). The mean tube current reduction depended on the body region: pelvis (13.2%), abdomen (8.4%) and thorax (3.3%). The image:quality was not significantly reduced in Group 2. Conclusion: The method for anatomically adapted tube current variation leads especially in the pelvis to a significant mAs reduction without considerable loss of image quality.