Do CT scans cause cancer?
Last updated September 3, 2026.
CT uses ionizing radiation, so a small theoretical cancer risk exists - and for a medically needed scan, the diagnostic benefit usually outweighs it clearly. Scale matters: the FDA's dose table puts a chest x-ray at 0.02 mSv, a CT head at 2, a CT chest at 7, and a CT abdomen at 8 - which is why the question is fair, and why repeated scanning and children's scans get the most caution.
What to do
- Take the needed scan. An undiagnosed problem is a certainty; the radiation risk is small and statistical.
- Ask about alternatives. Ultrasound and MRI carry no ionizing radiation and sometimes answer the same question.
- Keep a scan history. A list of your past CTs helps doctors judge cumulative exposure.
- Watch the duplicate trap. Bring prior images to new providers so scans are not repeated needlessly.
Related questions
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- What happens at an MRI?
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