Tube Current Modulation Reduces Computed Tomography Angiography Radiation Dose
NEW YORK, May 1, 2009 — The effective radiation dose received by patients undergoing "triple rule-out" coronary computed tomography angiography (CCTA) can be reduced by modulating the tube current, without loss of image quality, according to a report in the April issue of the American Journal of Roentgenology.
"We have been able to make definitive diagnoses in 15% to 20% of our patients and to safely discharge the majority of patients without further testing who are found to have negative triple rule-out studies," Dr Kevin M. Takakuwa told Reuters Health.
The triple rule-out protocol "examines for not only coronary artery disease but also aortic dissection, pulmonary embolism, and other chest diseases," he et al explained in their report.
"While there is radiation exposure involved, it can be greatly reduced with techniques such as dose modulation," the researcher said.
Dr Takakuwa from Thomas Jefferson University Hospital in Philadelphia, et al evaluated the reduction in effective dose through the use of electrocardiogram-based tube current modulation in emergency department patients who underwent triple rule-out CCTA for suspected acute coronary syndrome.
The effective radiation dose in 172 patients evaluated without tube current modulation averaged 18 mSv, the authors reported, compared with only 8.75 mSv in 95 patients who underwent CCTA with tube current modulation.
Image quality as judged by the interpreting radiologist was significantly better in patients imaged with tube current modulation than in patients imaged without tube current modulation.
In both groups (with and without tube current modulation), the effective radiation dose was lower for young patients than for middle-aged and older patients, and lower for normal-weight patients than for overweight and obese patients.
Women received less radiation than men did when tube current modulation was not used, the researchers noted, but there was no significant difference between men and women when tube current modulation was used.
"Diagnosing certain conditions is challenging, and the most definitive way to either make the diagnosis or to rule it out is often with CT," Dr Takakuwa commented. "From my perspective, it is more important for patient well-being to rule in or rule out a life-threatening condition now than to worry about the long-term potential consequences of radiation, particularly using a test that is less radiation than commonly used alternative tests."
Nonetheless, "Like all physicians, we are concerned about minimizing radiation expose in our patients," Dr Takakuwa added. "Not only are we asking our patients about their radiation concerns, we are working with new CT techniques like step-and-shoot as a way to further decrease radiation for triple rule-out coronary CTA."
Source: Reuters Health Information
