CT Scans Can Triple Brain Cancer Risk
People who are exposed to two or three CT scans as children are three times more likely to develop brain cancer as they get older, according to a new study, published in the Lancet medical journal on Wednesday.
A CT scan, also known as an X-ray computed tomography, is an imaging test used to generate a three-dimensional image of the inside of an object, such as the head, to look for damage.
"It's well known that radiation can cause cancer but there is an ongoing scientific debate about whether relatively low doses of radiation, like those received from CT scans, do increase cancer risks, and if so the magnitude of those risks," Amy Berrington de Gonzalez, study coauthor and researcher with the National Cancer Institute, told Reuters. "Ours is the first study to provide direct evidence of a link...and we were also able to quantify that risk."
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Researchers followed over 180,000 people over 20 years and found that for every milligray (mGy) of radiation, a dosage measurement, a patient receives, their risk of brain cancer increases by .023. The average head CT scan is 2 mGy's, according to RadiologyInfo.
Researchers also found that repeated CT scans ups the risk for leukemia as well, with every mGy of radiation increasing the risk by .036.
A total of 74 out of 178,604 patients were diagnosed with leukemia and 135 of 176,587 were diagnosed with brain cancer, according to Reuters.
"CT scans are very useful, but they also have relatively high doses of radiation, when compared to X-rays," Mark Pearce, study author and researcher from Newcastle University, said, according to Fox News.
Pearce said more needs to be done to cut back on the amount of radiation children receive. He advocates asking for the lowest radiation dose possible, avoiding multiple scans, and asking for an ultrasound or MRI instead, which do not use radiation.
However, the researchers said parents should be afraid of CT scans -- they're valuable diagnostic tools.
"If an imaging scan is warranted, the immediate benefits outweigh what is still a very small long-term risk," Dr. Marta Schulman, a pediatric radiologist and chair of the American College of Radiology's Pediatric Imaging Commission, told CNN. "Parents should certainly discuss risk with their provider, but not refuse care that may save and extend their child's life."
David Spiegelhalter, an expert in the understanding of risk at Cambridge University, who was not directly involved in the research, told Reuters the risk needs to be seen in context.
"This study suggests there is around a 1 in 10,000 chance that a young person's CT scan will give them leukemia over the next 10 years," he said. "This study suggests there is around a 1 in 10,000 chance that a young person's CT scan will give them leukemia over the next 10 years."
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