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As CT Scans Add Up, So Does Radiation Risk
 Cancer Center Feature Story

As CT Scans Add Up, So Does Radiation Risk
Not having the test, though, could be more dangerous

'As CT Scans Add Up, So Does Radiation Risk(HealthDay News) -- For many patients and their doctors, CT scans can be a lifesaving glimpse inside the body. But the higher dose of radiation that the scans use may put some people at risk for cancer.

The procedure uses special X-ray equipment to get detailed, cross-sectional pictures of organs, bones and other tissues to detect or track the progression of tumors, or even find a blood clot.

But researchers from Harvard University found that because the scans involve a higher dose of radiation than other imaging tests, cumulative exposure can increase the risk for cancer by up to 12 percent.

"People should be aware that cumulative radiation risks do add up when they have numerous CT scans," Dr. Aaron Sodickson, assistant director of emergency radiology at Brigham and Women's Hospital in Boston, told HealthDay.

The study, led by Sodickson and published in Radiology, examined medical records from 31,462 people who had 190,712 CT scans over 22 years. About 33 percent had five or more scans, 5 percent had more than 22 and 1 percent had more than 38.

In all, 15 percent of the people in the study received cumulative radiation doses of more than 100 millisieverts (mSv), equal to 1,000 chest X-rays. For 4 percent, the cumulative amount reached more than 250 mSv, and it totaled more than 399 mSv for 1 percent of the group.

Radiation exposure boosted the risk for cancer by 1 percent above the U.S. cancer risk rate of 42 percent for about 7 percent of the participants. For the 315 people who had received the most radiation, their risk of cancer increased 12 percent, the researchers calculated.

Nonetheless, Sodickson said that most people need not worry. "Patients getting a small number of CT scans, they really shouldn't be very concerned at all" about increased cancer risk, he said.

In fact, the U.S. National Cancer Institute says that not having the procedure can be more risky than having it, especially if cancer is suspected, stressing that people considering CT must weigh the risks and benefits of the scan.

Dr. E. Stephen Amis Jr., chairman of the radiology department at Montefiore Medical Center in New York City, agrees that the dangers are real but that most people shouldn't lose sleep over it.

If you really need the test, you should have it, Amis said.

"People should not be lying awake at night wondering when they are going to get their cancer -- after one or two or five or six CT scans -- if they needed to have them done," he said.

But people with an ongoing health problem should be prepared to ask about less-dangerous testing options, Amis said.

"If you have a chronic problem like passing kidney stones, and every time you show up at the emergency department every six months, they get another CT scan rather than doing a less-dangerous [test] that doesn't use radiation, like ultrasound, you are being mis-served, and CT is being overused," Amis said.

On the Web

To learn more about CT scans, visit the U.S. National Cancer Institute.

SOURCES: HealthDay News; Aaron Sodickson, M.D., Ph.D., assistant director, emergency radiology, Brigham and Women's Hospital, Boston; E. Stephen Amis Jr., M.D., chairman, radiology, Montefiore Medical Center, New York City; April 2009, Radiology; U.S. National Cancer Institute (
Author: Dennis Thompson
Publication Date: March 31, 2010
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