Certain hospitals and medical facilities are aggressively advertising low-cost computerized tomography (CT) scans. These scans sometimes cost just a few hundred dollars or less, a fraction of the price typically charged. Some even are free. Why? So the medical facility will get your business if any treatment is needed.

A CT scan combines a series of X-ray views of the body taken from many different angles. But it’s usually not a good idea to get a CT scan unless your doctor provides a specific medical reason why you need one. Each CT scan you get during your lifetime exposes you to radiation, increasing your risk for cancer. Also, though “precautionary” (not ordered for a specific reason) CT scans often are advertised as offering “peace of mind,” they are likely instead to cause unnecessary health scares. The issues they turn up frequently turn out to be false alarms.

Potential exception: A recent study suggests that there could be some benefit to precautionary chest CT scans for certain long-term heavy smokers. This applies only to people ages 55 to 74 who have smoked a pack or more a day for 30 years or more.

An advertised low-cost CT scan could be worth investigating if your doctor has a legitimate reason to recommend a CT scan and you lack health insurance or you would have to pay a significant amount out of pocket for the scan under the terms of your policy. Contact the hospital recommended by your doctor (and your insurer if you have one) to ask how much you would have to pay for the scan. If it’s more than a few hundred dollars, ask your doctor if he/she knows of any way to lower that CT scan cost—many hospitals have programs to help the uninsured and underinsured pay these bills. If not, ask your doctor if he thinks highly of the facility that’s been advertising low-cost CT scans. If your doctor cannot recommend the facility, don’t use it—there’s little point in having a CT scan done at a facility that cannot be trusted to interpret it correctly. Alternatively, call around to other hospitals and medical facilities in your area, and ask them to quote you their prices for the CT scan you need. Rates can vary dramatically.