Is it safe to get repeated imaging tests?

Radiation from diagnostic tests has the potential to damage tissue in the body, including cell DNA. Rarely, that can cause cell mutations that lead to cancer 10 or 20 years later. The long-term cancer risk from standard x-rays is considered very low; the risk from computed tomography (CT) scans might be higher. If a doctor orders a CT scan for someone who recently had that same type of scan, the patient should ask what the results might show, whether they’ll affect treatment, and whether an alternative test can be substituted.