Which is safe and mri or ct scan?

Both are safe.....: Mri has no ionizing radiation, thus there is no risk of radiation induced cancer. However, MRI is not for everyone. If you are claustrophobic, have a heart pacer, or have shrapnel you may not be able to have an mri. Ct does have radiation, but the dose is very small and in most cases less than you are exposed to just by living on earth for one year. You, your doc and radiologist should decide.

Depends ...: Both examinations have risk, albeit low. Mri does not expose patients to ionizing radiation whereas ct does. However, if contrast (intravenous) were to be used - there are risks in both types of scans. Contrast for MRI and ct can result in allergic reactions, renal damage, and other adverse side effects. Consult with your physician to determine risk/benefit for either exam.