Does a CT scan use a lot of radiation?

A CT scan uses X-rays, which are a form of ionizing radiation. The dose is higher than a plain X-ray, but the National Cancer Institute notes that the increase in cancer risk from a single CT scan is still small.

For comparison, a typical chest CT (about 6 mSv) is roughly the amount of natural background radiation a person receives in about two years. NCI emphasizes that when a CT scan is used to diagnose a serious condition in someone with symptoms, the benefits greatly outweigh the potential risks.

It's reasonable to ask your doctor whether a scan is needed and whether an alternative without radiation would work — especially for children, who are more sensitive to radiation.