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Dose-reduction techniques may make cardiac CT safer

Reuters Health • The Doctor's Channel Daily Newscast

NEW YORK (Reuters Health) – Use of radiation dose-reduction techniques can decrease the amount of radiation a patient receives during cardiac CT angiography (CCTA) without compromising image quality, according to a report in the Journal of the American Medical Association for June 10.

Prior research has suggested that CCTA can be used to definitively rule out the presence of coronary artery disease in appropriately selected patients. However, use of this imaging modality has been limited due to concerns of substantial radiation exposure from repeat scanning.

“The technique of CCTA is particularly amenable to radiation dose reduction using hardware and acquisition protocols customized to patients’ characteristics,” Dr. Gilbert L. Raff, from William Beaumont Hospital, Royal Oak, Michigan, and colleagues explain. However, whether reduction of the radiation dose would impair image quality was unclear.

To investigate, the researchers analyzed data from 4862 patients who were evaluated with CCTA before, during, and after dose-reduction techniques were implemented. Regarding the intervention, the authors note that “a best-practice CCTA scan model was used, which included minimized scan range, heart rate reduction, ECG-gated tube current modulation, and reduced tube voltage in suitable patients.”

Use of the dose-reduction techniques was associated with a 53.3% reduction in the patients’ estimated median radiation dose and with a drop in the effective dose from 21 to 10 mSv (p < 0.001 for both).

No significant changes in median image quality or frequency of diagnostic-quality scans occurred with use of the dose-reduction techniques.

The authors comment that additional studies are now needed to determine if CCTA doses could be reduced even further through the use of newer techniques, such as prospectively triggered scanning and single-heartbeat acquisitions.

JAMA 2009;301:2340-2348.