Optimization of CTCA Protocols Offers Significant Radiation Dose Reduction

Optimization of protocols during computed tomography coronary angiography (CTCA) using prospective electrocardiogram (ECG) gating and breast shields can reduce the radiation dose delivered to the female breast by more than 80%.

CTCA is a common, noninvasive procedure that is used to evaluate the coronary arteries. Prospective ECG gating is an imaging technique that allows radiologists to scan only during a certain phase of the heart beat cycle. Breast shields are placed over the chest during a CT exam to block out primary X-ray beams, which are responsible for most of the breast radiation during a CT study.

"As cardiac CTCA has significant potential for the noninvasive imaging of coronary artery disease, its utilization is continuously increased, particularly among young women,” said Sobhi Abadi, M.D., lead author of the study. "Therefore, the radiation dose delivered to the female's breasts should be addressed.”

Researchers from the University Health Network (Toronto, Canada), scanned an adult female phantom using eight different CTCA protocols. "The highest breast dose (82.9 mGy) was associated with using retrospective ECG gating. The lowest breast dose (15.2 mGy) was achieved with prospective gating with narrow exposure window, resulting in an 82% reduction in breast dose. The use of surface breast shields resulted in an additional 38% reduction in breast dose,” said Dr. Abadi.

The study was presented May 4, 2010, at the American Roentgen Ray Society (ARRS) 2010 annual meeting held in San Diego, CA,USA. "All use of ionizing radiation requires constant vigilance to ensure appropriate utilization and this is certainly true for CTCA,” Dr. Abadi concluded. "Significant reductions in radiation dose will reduce the statistical likelihood of causing genetic damage and long-term risk of adverse results.”

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