U.S. Panel Backs Routine Lung CT Scans for Older, Heavy Smokers

Yearly testing will prevent some lung cancer deaths, experts conclude

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Cutting Unneeded CT Scans in Kids Could Lower Future Cancer Risk

MONDAY, June 10 (HealthDay News) -- Reducing the number of unnecessary and high-dose CT scans given to children could cut their lifetime risk of associated cancers by as much as 62 percent, according to a new study.

CT (computed tomography), which uses X-rays to provide doctors with cross-sectional images of patients' bodies, is frequently used in young children who have suffered injuries.

Researchers concluded that the 4 million CT scans of the most commonly imaged organs conducted in children in the United States each year could lead to nearly 4,900 cancers in the future.

They also calculated that reducing the highest 25 percent of radiation doses could prevent nearly 2,100 (43 percent) of these future cancers, and that eliminating unnecessary CT scans could prevent about 3,000 (62 percent) of these future cancers.

The study was published online June 10 in the journal JAMA Pediatrics.

"There are potential harms from CT, meaning that there is a cancer risk -- albeit very small in individual children -- so it's important to reduce this risk in two ways," study lead author Diana Miglioretti, a professor of biostatistics in the department of public health sciences at the UC Davis Health System, in California, said in a health system news release.

"The first is to only do a CT when it's medically necessary, and use alternative imaging when possible," she said. "The second is to dose CT appropriately for children."

The researchers examined data on the use of CT in children at a number of health care systems in the United States between 1996 and 2010. Among children under 5 years old, CT use nearly doubled from 11 per 1,000 in 1996 to 20 per 1,000 between 2005 and 2007, and then decreased to about 16 per 1,000 in 2010.

Among children aged 5 to 14, CT use nearly tripled, from 10.5 per 1,000 in 1996 to a peak of 27 per 1,000 in 2005, before falling to about 24 per 1,000 in 2010.

Researchers examined 744 random CTs of the head, abdomen/pelvis, chest and spine conducted on children between 2001 and 2011 at five of the health systems to calculate radiation exposure levels and estimated cancer risk. These areas of the body account for more than 95 percent of all CT scans, the researchers said.

Head CT -- the most commonly performed CT in children -- poses the highest risk of radiation-induced leukemia and brain cancers, according to the study. Meanwhile, CTs of the abdomen and pelvis -- which had the most dramatic increase in use, especially among older children -- pose the highest risk of radiation-induced solid cancer. Leukemia and breast, thyroid and lung cancers account for 68 percent of estimated future cancers in girls who have had CTs, while leukemia and brain, lung and colon cancers account for 51 percent of future cancers in boys who have had CTs.

More information

The American College of Radiology/Radiological Society of North America has more about CT scans and children.

SOURCE: UC Davis Health System, news release, June 10, 2013

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Child CT Scans Might Up Risk of Brain Cancer, Leukemia

AppId is over the quota
AppId is over the quota

WEDNESDAY, June 6 (HealthDay News) -- Children who undergo CT scans of the head may raise their risk of developing brain cancer or leukemia later in life, a new study says.

Although multiple CT scans could triple the risk, the absolute risk remains small -- one case in 10,000 scans of the head, the researchers said.

"We have shown small increased risks associated with the radiation exposures from CT," said study co-author Louise Parker, from the Canadian Cancer Society and a professor of medicine and pediatrics at Dalhousie University in Halifax, Nova Scotia.

"As long as CT is used only where justified, then the benefits of CT, a potentially lifesaving modality, will almost certainly outweigh the risks," she said.

Lead study author Amy Berrington de Gonzalez, from the U.S. National Cancer Institute, said this study is the first to look at the actual cancer risk of radiation from CT scans.

"All the previous studies about the potential risk of CT scans have been theoretical studies using models from other radiation-exposed populations," she said. Specifically, they studied the results of radiation exposure after atom bombs were dropped on Japan during World War II.

For the new study, researchers collected data on almost 180,000 British patients under age 22 who had CT scans between 1985 and 2002. They looked at cases of leukemia, brain tumors, how many scans were done and radiation dose absorbed by the brain and bone marrow.

Seventy-four patients developed leukemia, and 135 developed brain cancer. The researchers calculated that the relative risk for leukemia increases 0.036 for every extra milli-Gray (mGy) used, and the risk for brain tumors, 0.023 per additional mGy.

Using these data, they further calculated that one head CT scan before age 10 would result in one excess case of leukemia and one excess brain tumor per 10,000 patients in the 10 years after first exposure.

Children are more sensitive to radiation than adults, said the authors, adding that there are steps that parents can take to help limit the risk if a doctor calls for a CT scan on a child.

"Parents should talk to their health care providers and ask for the reasons for the scan, if one is recommended," Berrington de Gonzalez said. "They can also check if CT scanners are set appropriately for the age and size of the child to ensure that the doses are optimized. If this is done, the benefits of the scan should outweigh the small cancer risk."

The study appears in the June 7 online edition of The Lancet.

Richard Morin, chair of the American College of Radiology's Dose Index Registry and chief medical physicist at the Mayo Clinic in Jacksonville, Fla., said this is an epidemiological study that shows an association, but not necessarily a cause-and-effect relationship.

However, "CT scans should be used wisely, and there should be a medical reason why the scan is being done and as long as there is a sufficient medical reason then the benefit far outweighs the risk with regard to radiation," he said. "It's not zero. However, it's a better approach than surgery with sedation and its possible complications."

Parents should ask their doctor if the procedure is necessary or whether there are different tests that can get the same information without radiation, such as ultrasound or an MRI, Morin said.

Parents should also keep track of the tests done and the radiation levels used so they can show doctors if their child is seen at different facilities, he said.

The American College of Radiology recommends that parents ask their child's pediatrician or other provider who orders a scan these other questions:

Recently, to make sure children are not exposed to more radiation than necessary when they get X-rays or CT scans, the U.S. Food and Drug Administration asked the makers of these devices to factor in the safety of pediatric patients when using existing machines and designing new ones.

If the manufacturers can't show their equipment is safe for children, the FDA wants labels on the machines that say so.

More information

For more about imaging tests, visit the U.S. National Library of Medicine.

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