CT scans, X-rays and Radiation

How much exposure to radiation is too much?

One of the surprising things about President Obama having a virtual colonoscopy and the brouhaha about reducing the frequency of mammograms is that, at exactly the same time, multiple stories appeared in the press about the risks of excessive exposure to radiation from CT scans and X-rays, especially for children. There also have been hearings in Congress on the subject and now the FDA is weighing in. For background, try this NY Times story about radiation overdoses in hospitals during "routine" CT-scans and this more recent story about how "hundreds of hospitals across the country needlessly exposed patients to radiation by scanning their chests twice on the same day."

I don't think people are making the connections. They should be questioning whether these procedures are too frequent and whether the doses are too high.

Most ionizing radiation we experience comes from nature but the balance is shifting. The amounts used in CT scans can be as much as 400-500 times that of an X-ray and while there is no question in my mind that these procedures are medically useful, the doses are cumulative and can actually raise the risk of cancer. The rate of Americans getting CT scans and MRIs has tripled between 1996 and 2006, according to the National Center for Health Statistics, and it’s now about 70 million annually. Studies in The New England Journal of Medicine have said that up to a third of those CT scans are unnecessary. Radiologists tend to disagree of course but some doctors and technicians are scaling back usage and dose amounts. Should we exercise the same concern about MRIs which use powerful magnetic fields? This is not the place to wade into concerns about radiation from excessive cel phone use, cel phone towers and so on (more here), but it does add up.

In October of 2009 it was revealed that 250 patients at Cedars-Sinai Medical Center received overdoses at up to eight times as much radiation as intended. This reveals that the (mis-)application by medical staff is as big a problem as the technology.

In November 2009, concerned about excessive radiation through over-screening in mammographies, the U.S. Preventive Services Task Force recommended that women wait until age 50 to begin regular tests, and then get them every two years. The American Cancer Society (among others) went ballistic. The ACS just updated its prostate cancer screening guidelines and – rightly - it urges caution and making patients more informed, but it omits the dangers of radiation from treatment.

In December 2009, there were complaints about the over-exposure of children and the over-use of CT scans. Articles in the Archives of Internal Medicine warned of a significant increase in cancer related to CT scans. Apparently 5-10% of all CT scans are conducted on children.

Now that there has been an explosion of stories in the press about the risks from radiation, there still seems to be a disconnect in people’s minds between CT scans and X-rays and the albeit unlikely possibility of accelerating cancer. It all may be a vicious circle.