There is no conclusive evidence that radiation from diagnostic or interventional x-rays causes cancer. However, some studies of large populations exposed to radiation have demonstrated slight increases in cancer risk even at low levels of radiation exposure, particularly in children. To be safe, doctors should presume that even low doses of radiation may cause harm.
A person's cancer risk from having a medical procedure should be evaluated against the statistical risk of developing cancer in the entire population. The overall risk of a person dying from cancer is estimated to be 20-25 percent. This means that out of every 1,000 people, between 200-250 will eventually die of cancer even if they never had a single x-ray, CT scan, etc., in their entire life. Doctors and scientists are not entirely sure how much a medical radiation procedure will increase a person's risk of dying from cancer (above the 20-25 percent). Doctors estimate that the increased risk of cancer over a person's lifetime from a single CT scan is very small, only 0.03 to 0.05 percent.
These cancer risk estimates are averages for the U.S. population. Any individual's cancer risk might be higher or lower depending on a number of factors, including age, lifestyle and heredity.
Like any medical test, the beneficial information gained from diagnostic imaging procedures should outweigh the risk of having the test performed. Medical imaging is a very powerful and valuable technique that can provide important and even life-saving information.