Americans are now exposed to about seven times more radiation on average than they were in 1980, new research finds, and medical scans may be the reason.
A report published by the National Council on Radiation Protection and Measurement examined radiation exposure in the U.S. population from all sources. The greatest increase in radiation exposure, it found, came from physicians having more and more patients undergo diagnostic imaging tests, which use radiation.
"The increase in medical [radiation] exposure was not a big surprise to anybody," said Kenneth Kase, executive vice president of NCRP. "We expected [radiation] exposures for medical uses to increase dramatically because of the increase in the use of CT scanning in the last 20 years."
While most experts believe that the benefits of diagnostic imaging tests such as CT scans far outweigh the risks, some worry the rise in radiation exposure could lead to many more cancer cases in the future.
"Radiation exposure from these scans is not inconsequential and can lead to later cancers," said Dr. Len Lichtenfeld, deputy chief medical officer for the national office of the American Cancer Society. "This doesn't mean people shouldn't get CT scans, but it does mean we need to be very careful in how we use these technologies in the future."
The report also found that while CT scans account for only 17 percent of the total medical procedures that expose patients to radiation, the CT scan accounts for nearly half (49 percent) of all medical radiation exposure and nearly a quarter (24 percent) of all sources of radiation exposure.
A great deal of the current understanding of the risks associated with radiation-induced cancer stems from studies performed on the survivors of the 1945 atomic bombings on Japan.
A study published in the November 2007 issue of the New England Journal of Medicine notes that those survivors who were exposed to low doses of radiation -- about the equivalent of the dose administered to an adult patient undergoing two or three CT scans -- still experienced a significant increase in their overall cancer risk.
The American College of Radiology estimates that 72 million CT scans were performed in the United States in 2006.
Many experts are concerned that physicians are overusing such tests. An issue of particular concern is that some physicians may be referring more patients to undergo unnecessary medical tests because they are benefiting financially by offering these tests in their practices.
"Our medical care system is rewarding doctors much more for ordering and reading scans than for talking to a patient," Lichtenfeld said.
Medicare statistics show that the number of physicians referring patients for radiological testing in their private practices in which they have a financial stake grew at triple the rate of the same exams in other settings between 1998 and 2005.
"I think [this] is one of the reasons we have the problem with increased background radiation due to medical imaging," explained Dr. Stephen Amis, chairman of radiology at the Montefiore Medical Center in New York. "Physicians are trying to augment income in every way possible in this time of decreasing reimbursement. It's not too hard to come up with a reason to image patients while they're seeing you in the office, and that's an ongoing concern."