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  • Radiology in Public Focus

    April 01, 2013

    Body CT Scanning in Young Adults: Examination Indications, Patient Outcomes and Risk of Radiation-induced Cancer

    Among young adults undergoing body CT, risk of death from underlying morbidity is more than an order of magnitude greater than death from long-term radiation-induced cancer, according to new research.

    Robert L. Zondervan, M.S., of Massachusetts General Hospital, Boston, and colleagues analyzed imaging records of patients 18 to 35 years old who underwent chest or abdominopelvic CT exams between 2003 and 2007 at one of three university-affiliated hospitals in Boston.

    Researchers accessed records from 22,000 patients, including 16,851 chest and 24,112 abdominopelvic CT scans. During the average 5.5-year follow-up period, 7.1 percent of young adults who underwent chest CT and 3.9 percent of those who had abdominopelvic CT died: figures that were much greater than the 0.1 percent long-term risk of death from radiation-induced cancer predicted by statistical models in both groups.

    Radiation reduction efforts should also focus on patients who are very rarely scanned rather than exclusively on those who are scanned repeatedly, according to the authors. “When consulting on radiation concerns, the radiologist should counsel that the underlying medical morbidity, rather than CT-induced cancer, is the much greater driver of a potentially adverse patient outcome,” the authors write.

    Obstructive coronary CT angiogram of proximal portion of obtuse margin
    Obstructive coronary CT angiogram of proximal portion of obtuse margin (OM, arrows) in 67-year-old man (height, 67.7 cm; weight, 176 kg; body mass index, 29.5 kg/m2; effective diameter, 31.3 cm; heart rate, 44 beats per minute). Nonobstructive mixed calcified and/or noncalcified coronary artery disease (*) of proximal left anterior descending coronary artery (LAD) was present on the invasive angiogram. Estimated effective radiation dose was 0.90 mSv (dose-length product, 64.1 mGy × cm; CTDI, 5.3 mGy; SSDE, 6.16 mGy). (Radiology 2013;267;1:76–85 ©RSNA, 2013. All rights reserved. Printed with permission.

    Submillisievert Median Radiation Dose for Coronary Angiography with a Second-Generation 320–Detector Row CT Scanner in 107 Consecutive Patients

    The combination of a gantry rotation time of 275 milliseconds, wide-volume coverage, iterative reconstruction, automated exposure control and larger X-ray power generator of the second-generation CT scanner provides excellent image quality over a wide range of body sizes and heart rates at low radiation doses, according to new research.

    Marcus Y. Chen, M.D., of the National Institutes of Health, Bethesda, Md., and colleagues performed contrast-enhanced coronary CT angiography (CCTA) with a second-generation 320-slice CT system on 107 adult patients (mean age, 55.4) and compared radiation exposure and image quality to those of CCTA exams previously performed on 100 patients using a first-generation 320-slice scanner.

    Effective radiation dose was estimated by multiplying the dose-length product by an effective dose conversion factor and reported with size-specific dose estimates (SSDE). Image quality was evaluated by two independent readers.

    The median radiation dose was 0.93 millisieverts (mSv) with the second-generation unit and 2.67 mSv with the first-generation unit. The median SSDE was 6.0 milligray (mGy) with the second-generation unit and 13.2 mGy with the first-generation unit. Overall, the radiation dose was less than 0.5 mSv for 23 of the 107 CTA examinations (21.5 percent), less than 1 mSv for 58 (54.2 percent), and less than 4 mSv for 103 (96.3 percent). All studies were of diagnostic quality with most having excellent image quality.

    “Minimizing radiation exposure while maintaining diagnostic-quality scans is clearly feasible with this new second-generation 320–detector row CT scanner,” the authors write. “The low dose achieved during CTA could be used to minimize overall radiation dose to the patient or to enable additional types of imaging (e.g., perfusion imaging) within reasonable radiation doses.”

    Media Coverage of RSNA

    In January, 4,016 RSNA-related news stories were tracked in the media. These stories reached an estimated 4 billion people.

    Print coverage included USA Today, Detroit Free Press, Las Vegas Review-Journal, Palm Beach Post, Baltimore Sun, The Wall Street Journal, Boston Globe and Investor’s Business Daily.

    Broadcast coverage included WPIX-TV (New York), WLS-TV (Chicago), WGN-TV (Chicago), WMAQ-TV (Chicago) and WCVB-TV (Boston).

    Online coverage included Yahoo! News, The Huffington Post, MSNBC, The Wall Street Journal, The New York Times, Forbes, and U.S. News & World Report.

    Total RSNA 2012 annual meeting media coverage through February 11, 2013, has resulted in 10,077 tracked media placements, yielding an estimated potential audience/circulation of more than 6.3 billion.

    Notable placements for RSNA 2012 include: USA Today, The Wall Street Journal, The Washington Post, Bloomberg News, Daily Mail and The Daily Telegraph.

    RadiologyInfo.org Posts New “Your Radiologist Explains” Videos

    RadiologyInfo.org, the RSNA and American College of Radiology (ACR) public information website, will soon have 22 new video clips to help explain various radiology tests and treatments to patients. In addition, some of the videos will focus on explaining diseases or conditions that are either diagnosed or treated using radiology. These videos, which include topics such as cardiac CT, lung cancer, blood clots, pneumonia, brain tumors and more, are the latest in the “Your Radiologist Explains” series to provide website visitors with a unique format for learning about radiology procedures.

    The videos feature PowerPoint presentations with images and narration. All presentations were created by members of the RSNA-ACR Public Information Website Committee. Visit RadiologyInfo.org/vids.

    Read coverage of RSNA in these media:

    April Outreach Activities Focus on Coronary Artery Disease

    In April, RSNA is distributing the “60-Second Checkup” audio program to nearly 100 radio stations across the U.S. The segments focus on the use of CT scanning to depict racial differences in coronary artery disease.

    Common examination indications according to frequency of scanning
    Above: (a, b) Common examination indications according to frequency of scanning. The four most common reasons for chest (a) and abdominal (b) CT are shown in scanning frequency group, with 95 percent confidence intervals indicated. (Radiology 2013;267;InPress) ©RSNA, 2013. All rights reserved. Printed with permission.
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