CT Scans, Other Imaging Tests Becoming More Common
CT Scan Rates Tripled at HMOs in the Last 15 Years, Doubling Radiation Exposure to Patients
Concerns Over CT Scans continued...
"We do know that the higher dose will be associated with a much higher risk of cancer," says researcher Rebecca Smith-Bindman, MD, a radiologist and professor in residence at the University of California at San Francisco.
Although the current study did not look at the health effects of radiation, another one published last week in The Lancet found that children who have repeated CT scans before age 15 are at higher risk of brain tumors and leukemia.
Smith-Bindman says the risk of getting cancer from any one scan appears to be very small. But over time, doses may accumulate, increasing the risk. She says they will be looking at this issue in a future study.
The study also showed that doses of radiation delivered to patients can vary widely for the same test, depending on where it's performed. "Very few facilities know the doses they're using. They don't collect them. They don't look at them, so that's a huge problem," she says.
Though radiologists sometimes use higher doses of radiation to get a clearer image, Smith-Bindman says doses have escalated beyond the range that's needed for image clarity. "The doses are so much higher than they need to be," she says.
And researchers say that they found some evidence that testing was being ordered when it might not be needed.
"We know that in a lot of the cases, the CT really isn't necessary and maybe you can wait. Or if the CT is necessary, then maybe you can just go lower dose," Diana L. Miglioretti, PhD, tells WebMD. She is a senior investigator and biostatistician at the Group Health Research Institute in Seattle.
Miglioretti says the doses of radiation they documented in the study were chilling when viewed in the light of the risks of brain tumors and leukemia documented in the recent Lancet paper.
Assuming typical average doses for CT scans, The Lancet study found that having two to three CT scans of the head before age 15 exposed children to radiation levels that could triple a child's risk of having a brain tumor.