CT Scans and Cancer Risks

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January 15th, 2013

ct scan overuse cancer risksThe use of CT scans (and medical imaging in general) is rising and with it the amount of patient exposure to radiation. A recent JAMA study found that the rate of CT scan use had increased by 20% between 1996 and 2010. CT scans are now said to be responsible for three-fourths of Americans’ exposure to radiation with more than 10% of patients receiving extremely high exposure through CT scans each year.

A CT scan, or computed tomography scan, takes a number of X-Rays from various angles and combines them to create cross-sectional images. CT scans however contain about 100 – 500 times the radiation of traditional X-Rays. This amount of radiation has the potential to cause irreparable damage to DNA and ultimately lead to cancer.

Cancer Risks & CT Scans

In 2001, a major study on CT scan risks predicted that of 600,000 children under the age of 15 who had head and abdominal scans each year, 500 may ultimately die of cancer caused by the CT scan radiation.  In fact, children under 15 who have had 2-3 head scans have triple the risk of developing brain cancer compared to general population. Children receiving 5-10 scans triple their risk of being diagnosed with leukemia.

Adults are also at risk of having adverse effects from exposure to radiation. One study from the National Cancer Institute estimated that there would be approximately 29,000 future cancers related to scans done in 2007 alone. That year, Americans had about 72 million total CT scans.

The Overuse of CT Scans

Even more worrisome is the fact that numerous studies show that at least 30% of all CT scans are completely unnecessary. Overuse of CT scans can be attributed to several reasons.  Doctors worry about the possibility of lawsuits and try to minimize uncertainty by ordering a CT scan. Lack of adherence to best practices and evidence based medicine is also a leading cause of overuse. Other providers and facilities try to recoup the costs of purchasing their own CT scanner or simply order the tests for financial gain. There are even cases where doctors would rather perform another CT scan than contact the previous provider for the patient’s medical records. Patients also play a role in the overuse of CT scans, demanding to have more tests in order to ensure they are receiving the ‘best care’ possible. Many patients are also unaware of the radiation risk of CT scans with only one in 20 patients believing that a scan would increase their chance of ever getting a cancer.

What can be done?

Recognition of the overuse of medical imaging and the harmful effects of radiation has prompted numerous experts to call for more careful consideration before ordering the use of medical radiation. Close adherence to evidence based practices and guidelines can be of great value when determining the appropriate use of medical radiation and balancing the potential risks against the known benefits. There are many conditions (such as appendicitis) for which a CT scan should not be the first imaging technology used. Instead an alternative imaging technology such as an ultra-sound should be used.  Practitioners should also ensure that the lowest amount of radiation possible is being used when conducting the imaging test and make an effort educate patients on the risks of the CT scan.


2 Comments

  • Les says:

    Can you post more details of the 2001 major study and who the authors are?

    Cancer Risks & CT Scans

    In 2001, a major study on CT scan risks predicted that of 600,000 children under the age of 15 who had head and abdominal scans each year, 500 may ultimately die of cancer caused by the CT scan radiation. In fact, children under 15 who have had 2-3 head scans have triple the risk of developing brain cancer compared to general population. Children receiving 5-10 scans triple their risk of being diagnosed with leukemia.
    Adults are also at risk of having adverse effects from exposure to radiation. One study from the National Cancer Institute estimated that there would be approximately 29,000 future cancers related to scans done in 2007 alone. That year, Americans had about 72 million total CT scans

    • Chenoa says:

      Thank you for your comment Les!

      The study on CT risks to children, "Estimated Risks of Radiation Induced Fatal Cancer from Pediatric CT" was published in 2001, and based off of the Japanese atomic bombing exposure. The first author of the study is David Brenner. You can find more about the study here.

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