When your children are sick, it's hard not to want doctors to do everything in their power to cure them. But when it comes to CT scans, less is often more.
That's because CT scanners -- which use X-rays to produce richly detailed images of almost any part of the body -- deliver far higher doses of dangerous ionizing radiation than any other commonly used medical imaging device. And children, for a host of reasons, are even more susceptible to the carcinogenicity of ionizing radiation than adults.
Scientists have, of course, understood the risks of ionizing radiation for nearly a century. For a couple of decades after the advent of CT scanners in the mid-1970s, though, doctors generally believed that CT scans delivered such a small dose of radiation that they didn't endanger patients' health. But a growing body of evidence shows this could be a mistaken belief.
Dr. Rebecca Smith-Bindman of the University of California-San Francisco, a leading expert on the effects of medical imaging, told The Huffington Post that research suggests just one CT scan can triple a child's risk of developing some types of cancer. As many as 1 in 300 children who get a CT scan of the abdomen, chest or spine will eventually develop a tumor as a result of the radiation, she said.
"The doses used for CT are in the same range where we've seen direct evidence of harmful effects," Smith-Bindman said. "The median dose that people got in Hiroshima was 40 millisieverts. And we find that those are doses that patients get all the time."
The prevailing belief that CT scans were relatively harmless allowed their use to grow exponentially over the past couple of decades. Yet there are signs that children's hospitals, at least, are starting to take the risks of CT scans into account and cut back on the imaging. A study published Aug. 24 in the journal Pediatrics found that the use of CT scans at children's hospitals has dropped sharply over the past decade.
The study's authors examined the medical records of about 150,000 children treated for the 10 conditions that most often call for CT scans at 33 children's hospitals around the country in 2004 and 2012. (Focusing on specific conditions helped them ensure that the changes they observed weren't the result of changes in the conditions that doctors were treating.) They found doctors became less likely to use CT scans in all 10 conditions, which included seizure, appendectomy and severe head trauma.
The drop was often quite steep. About 25 percent of children treated for seizures in 2004 got CT scans, but only 13.3 percent treated in 2012 did. The rate for abdominal pain declined from 37.7 percent in 2004 to 25.6 percent in 2012; for concussion, it dipped from 75.7 percent in 2004 to 62.8 percent in 2012.
The researchers found that in many cases, decreases in the use of CT scans were accompanied by increases in the use of ultrasounds and MRIs -- neither of which exposes patients to ionizing radiation.
One of the authors, Dr. Michelle Parker of the Cincinnati Children's Hospital, attributed this change to growing awareness of the risks of CT scans, which she said had encouraged doctors to consider alternatives more regularly.
"We are not advocating that all CT scans be replaced by other imaging modalities, or that doctors actively avoid them where they feel they are indicated," Parker wrote in an email to The Huffington Post. "However, this study suggests that physicians may be incorporating new research supporting other imaging choices to provide the safest care to patients by avoiding CT scans when possible."
Smith-Bindman said doctors working in other medical environments, including general hospitals, have been slower to cut back on CT scans than those in children's hospitals -- which actually makes this research more valuable.
"It suggests that we can do better; we've shown we can do better at these hospitals," she explained. "That's really quite important, because it says that if you put effort into doing this, then it's doable."