Patients who undergo CT scans are exposed to more radiation than they would have been with a plain X-ray. Studies have shown a small potential to increase your risk of cancer. If you're pregnant, your doctor might want to use a different test, for there's some concern about the impact of the radiation on the fetus. Also, if you don't know that you're allergic to iodine, you can have an allergic reaction to the dye.
What's the follow-up?
The number of times you'll have a CT scan will depend on your diagnosis and what you and your doctor decide works best. For example, if you are a cancer patient, you likely will undergo several CT scans.
If there's a finding on your CT scan that doctors can't quite figure out, you might have a follow-up scan to see if anything is growing.
For example, it's common to find benign nodules in the chest.
Sometimes they're too small, and doctors can't figure out whether they're actually benign. In that case, your doctor might have you undergo a CT scan periodically to ensure that the nodules aren't cancerous and growing tumors.
Dr. James Hendrix, a radiologist at Mercy Hospital Oklahoma City; the National Institutes of Health;
The Mayo Clinic.