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Overview

A CT (computed tomography) or CAT (computerized axial tomography) head scan looks inside your head and neck. CT and CAT scans are the same test. Special X-ray technology gives your healthcare provider a picture of your skull, brain, eyes, nasal passages, veins, arteries, and tissue. It’s a common test. It’s used for a serious head injury, stubborn headaches, brain and skull birth defects, brain diseases, and stroke. Healthcare providers decide when a person needs a CT head scan.

A machine is used for a CT scan. The machine is shaped like a giant cylinder. It’s attached to a long table that slides in and out of the machine. The technology takes multiple X-ray views of your head. It layers them on top of each other to create a 3-D image for your healthcare provider.

If you’re having a CT head scan, you’ll lie on the table during the procedure. You’ll be asked to remain still. It could take 30 minutes to complete. The machine is noisy; however, the test is painless. Children often have difficulties remaining still, so they may be given an injection of a medicine to make them sleep through the test. You probably won’t be given the results of the test at the time of the test.

Path to improved health

An injury or illness related to your head can be scary. However, the images provided by CT head scan can help your healthcare provider better diagnose and treat head and brain conditions. It also may reduce the need for you to have other medical procedures, including surgery.

Your healthcare provider may first do an office exam and discuss your symptoms. Your healthcare provider also will look at the seriousness of your symptoms. That will help them decide if a head scan is necessary. If your head scan is not an emergency, it will be scheduled (an appointment).

In the event of an emergency, such as an accident, a serious injury, or stroke, healthcare providers can do a CT head scan through the emergency room. In those types of health emergencies, timing is critical. An emergency room doctor may need to do a head scan in order to diagnose, treat, and evaluate the damage a person may have suffered. For example, CT head scans are used to diagnose stroke. A person who has had a stroke has a better chance at recovery when examined and treated early. An emergency room head scan helps healthcare providers confirm that it was a stroke, evaluate the damage, and decide on further treatment.

For the head scan test, you may need to undress and put on a hospital gown. Some people must have a dye (contrast) injected into the vein in their arm for the CT head scan. The dye contains iodine. This makes it easier for certain parts and functions in your head or neck to show up on the image. Once the dye is injected, you may feel a burning sensation, the taste of metal, and a warm feeling in your body. These last only a few seconds. Some people are allergic to the dye (see “Things to consider”). Tell your healthcare provider if you know you’re allergic to dye.

Things to consider

Some people with poor kidney function caused by kidney disease or diabetes may need extra fluids after the test to help remove the iodine from their kidneys. People who have diabetes and are taking the medicine metformin should tell their healthcare provider before the test. Metformin and the dye can result in a serious drug interaction. The most serious allergy to the dye could cause difficulty breathing. If you have trouble breathing during the test, tell the scan technician immediately.

Like an X-ray, CT head scans will expose you to a small dose of radiation. One head scan image is made up of multiple X-rays. That’s how the technology creates a clear image of the inside of your head or neck. Therefore, a head scan exposes you to more radiation than a single X-ray. The exposure to radiation is small with one head scan.  The benefits of detecting disease are believed to outweigh the risks from receiving such a small radiation dose. The lowest amount of radiation needed to produce quality images is used.