COMPUTED TOMOGRAPHY scans, or CT scans, are one of the fastest-growing medical imaging procedures. Some 70 million of these scans, which use high doses of X-rays to give doctors a three-dimensional view of an area inside the body, are done in the United States every year. But there is ample reason to think that the overuse and misuse of these scans is needlessly putting some patients in harm’s way.
A single scan involves as much radiation as 100 to 800 conventional X-rays, and doses can be as high as those suffered by some nuclear bomb survivors. There is very strong evidence that such levels of radiation increase a person’s lifetime cancer risk. One study from the National Cancer Institute estimated that some 29,000 future cancers might result from the CT scans done in the US during 2007. Other studies estimate that about one of every 100 cancers in the US might result from CT scan radiation.
When medically justified, the benefit of the procedure for an individual patient — a potentially life-saving diagnosis — far outweighs the risks. But many CT scans are unnecessary. Kidney stone sufferers, for example, often get repeated CT scans even though safer alternatives, such as traditional X-rays, can be just as informative once a doctor is aware that a patient has had the condition before. Lack of communication between doctors means some patients receive duplicate scans. Meanwhile, the fear of litigation also contributes to the ordering of scans that may not be warranted.
Voluntary guidelines for how to perform a CT scan — what kind of dosage to use for a certain type of study in a certain patient — are by no means universally adopted. The machines themselves differ in how much radiation they emit. Thus, there can be significant variation — as high as 13-fold — between the radiation produced in the same type of CT scan in one facility versus another.
The Food and Drug Administration and the American College of Radiology are currently working to find solutions. Mandatory standards should be established, so that all facilities will follow the same rules. But the problem will not go away until both doctors and patients become more conscious about questioning the need for these scans in certain cases. When an ultrasound or a conventional X-ray can give the same answers, defensive medicine should give way to pragmatism. After all, the ultimate goal is saving people’s lives.