Imaging System Allows Shorter CT Scans at the Lowest Dose

A new dual-source computed tomography (CT) scanner requires only a fraction of the radiation dose that systems previously required to scan even the smallest anatomic details. A very fast scanning speed in CT (i.e., 43 cm/s) and a temporal resolution of 75 ms enable complete scans of the entire chest region in just 0.6 seconds. Thus, clinicians now have the option of not requiring their patients to hold their breath during the exam.

Siemens Healthcare (Eranlgen, Germany) announced the Mayo Clinic (Rochester, MN, USA) as the first medical facility in the United States to offer patients the innovations of the Somatom Definition Flash dual-source CT scanner.

"Interdisciplinary teamwork at Mayo, combined with industry collaborations like this, continues to support our hallmark mission of extraordinary patient care at Mayo. This second-generation dual-source CT scanner offers new applications that can benefit our patients while minimizing risks,” said J.G. Fletcher, M.D., from the Mayo Clinic. "Reduced radiation dose and scanning speed provide new opportunities for routine use of dual energy CT. This technique helps to highlight pathologies, giving Mayo an additional tool in patient diagnosis and treatment.”

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 8-20 mSv. (In comparison: The amount of radiation the average person is exposed to each year from naturally occurring sources is about 3 mSv.)

"With the introduction of the Somatom Definition Flash, Siemens took on CT's most pressing challenge and made dose reduction the centerpiece of our research,” said Kulin Hemani, vice president, computed tomography, Siemens Medical Solutions USA, Inc. (Malvern, PA, USA). "Its core innovation--the revolutionary flash spiral--was designed specifically to make CT exams much healthier for patients with Flash speed and lowest dose.”

The scanner was designed to reduce dose to patients. The X-Care application selectively reduces the radiation exposure to dose-sensitive anatomic regions, such as the female breast, by as much as 40%. Furthermore, an adaptive dose shield blocks irrelevant pre-spiral and post-spiral radiation, thus ensuring that only a minimum and clinically essential radiation exposure occurs. This enables an additional 25% reduction of the dose required for routine examinations.

With more than 35 years in CT imaging, Mayo's recent addition to its CT product range is part of ongoing collaborations between Siemens and Mayo's CT Clinical Innovation Center. The mission of the Center is to evaluate and make available the latest imaging science and CT technology for the benefit of patient care.

The system will help to usher in new levels of patient friendliness due to the speed of the scans. A full 2-meter scan requires less than five seconds; perfusion or dynamic vascular imaging becomes routine, and gated chest CT scans become sub-second procedures. A scan of the entire heart, for example, can be performed in only 250 milliseconds, which is about one-quarter of a heartbeat. Physicians can now reliably image a heart with a rapid or an irregular heartbeat without using betablockers, simplifying the workflow and yielding clinical and financial advantages.

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