The SOMATOM Definition CT scanner is the world’s first dual source CT. It uses two X-ray sources and two detectors at the same time (STRATON® tube technology). The design of this scanner removes cooling delays between multiple long range scans, even for large subjects. Rotation time of 0.33 sec with up to 64 slices per rotation acquisition enables early disease diagnosis or cardiac CT imaging. The scanner also enables high speed submillimeter volume coverage and whole body examinations within a breath-hold. Isotropic resolution is below 0.4 mm voxel size. The Definition’s two detectors offer acquisition of 2 x 64 slices per rotation. It has a large bore of 78 cm, scan range of 200 cm, and 160kW generator power. Sub-millimeter volume coverage of 87 mm/sec enables whole body examinations within a few minutes, reducing breath-hold time significantly.