By Genevra Pittman
NEW YORK (Reuters Health) - After years on the rise, the number of CT scans performed on kids every year seems to have started falling, according to a new study.
However, researchers found that U.S. children still have about 4 million head, chest, stomach or spine CT tests every year - which they believe will go on to cause close to 5,000 radiation-related cancers.
Many of those cancers could be avoided, either with lower-dose scans or no scans at all when they're not needed, according to Diana Miglioretti and her colleagues.
Parents should "ask if it's really medically necessary, or if there are other exams they can do," said Miglioretti, from the University of California, Davis, School of Medicine.
For example, some kids get a CT when they have belly pain and the doctor suspects appendicitis - but in that case, an ultrasound can often be done instead, she told Reuters Health.
Still, researchers said, there are many cases in which the more advanced imaging test is important to help doctors make a diagnosis and decide on the right type of treatment.
"In the case when a CT is medically necessary, it's important for parents to realize the benefit of a CT far outweighs any cancer risk," Miglioretti said.
She and her colleagues looked back at records of CT use at seven non-profit health systems between 1996 and 2010.
They found that in general, the number of CT tests given both to preschoolers and older kids increased until 2005, then leveled off and began to decline after 2007. In 2010, 16 out of every 1,000 kids under age 5 and 24 per 1,000 youth ages 5 to 14 had a head, chest, stomach or spine CT scan.
Radiation risks varied by type of scan as well as kids' age and gender.
For example, researchers expected one solid cancer to develop as a result of every 300 to 390 stomach and pelvis CT scans performed on girls and for every 670 to 760 given to boys.
One case of leukemia was expected to come from every 5,250 head scans on kids younger than 5 and for every 21,160 head CT tests among those ages 10 to 14.
Those calculations were based on data from Japanese atomic bomb survivors who were exposed to varying degrees of radiation.
In total, Miglioretti's team predicted that an estimated 4 million pediatric CT scans done over a year in the U.S. would be responsible for 4,870 future cancers, the researchers wrote Monday in JAMA Pediatrics.
Up to 62 percent of those could be prevented, they added, if doctors skipped the approximately one-third of CT tests that are unnecessary and lowered the dosing on necessary scans that use the highest radiation.
The American College of Radiology wrote in a statement that parents shouldn't delay or skip needed tests for their kids based on these findings.
"Diagnostic scans reduce the number of invasive surgeries, unnecessary hospital admissions and the length of hospital stays," the group said. "However, they must be used judiciously, when indicated, and when the needed information cannot be obtained in other ways, in order to minimize radiation exposure to all Americans - particularly children."
David Brenner, a radiology researcher at Columbia University Medical Center in New York, said parents should always feel comfortable asking if their child really needs a CT scan.
"Why not ask, ‘What are the reasons? What are you going to learn from the CT, and are there in fact other options?'" Brenner, who wasn't involved in the new study, told Reuters Health.
"Often, there will be a good answer from the physician," he said. But asking "is absolutely a reasonable thing to do."
SOURCE: http://bit.ly/1bpi6OI JAMA Pediatrics, online June 10, 2013.