Unnecessary CT Scans and Excessive Radiation Raise Cancer Risk

While CT (computed tomography) scans are undeniably useful, it may be time to reassess when they are necessary. Each scan exposes the patient to high amounts of radiation. This radiation is likely causing a large number of additional cancers. Because cancer from radiation takes a number of years to develop, it is particularly important to minimize unnecessary CT scans in younger patients.

The average radiation dose from a single CT scan was as high as what an individual would receive from 74 mammograms or 442 chest x−rays.

Two recent studies dealt with various aspects of this problem. One attempted to estimate the number of cancers caused by CT scans in the U.S. (1) The second sought to determine how much radiation patients are exposed to during CT scans, how much this radiation varied from procedure to procedure and to calculate the risk of a patient developing cancer from an individual CT procedure.(2)

Physicians don't seem to be taking this into account in deciding when to have a CT scan taken. An example is in patients who are known to have kidney stones. While a CT scan may provide information about the size and location of a kidney stone, it is unlikely to change the treatment. This is exactly the type of scan that may be doing a patient more harm than good. And some patients go directly from the emergency room to the CT scanner before they are even seen by a physician.

Because CT reveals information that might otherwise require exploratory surgery, its use has soared. There were approximately 3 million CT scans performed in 1980; by 2007 that number had increased to around 72 million. This means that patients are being exposed to an increasing amount of radiation. And radiation exposure at this level leads to increased numbers of cancers. The risks to individuals may be small, but because of the sheer number of persons exposed annually, this can add up to a considerable number of total cancers.