The Somatom Definition Flash is a new dual-source CT from Siemens, featuring two X-ray tubes that simultaneously revolve around the patient's body. The fastest scanning speed in CT (i.e., 43 cm/s) and a temporal resolution of 75 ms, enable for example complete scans of the entire chest region in just 0.6 seconds. Thus, patients are no longer required to hold their breath during the exam the way they had in the past. At the same time, the Somatom Definition Flash operates at an extremely reduced radiation dose. For example, a spiral heart scan can be performed with less than 1 millisievert (mSv), whereas the average effective dose required for this purpose usually ranges from 8 mSv to 40 mSv. The new CT scanner will be available for sale in the first quarter of 2009.