Head CT Scan


This handout explains how a CT head scan works, how to prepare, how it is done, what to expect during the scan, and how to get your results.

What is a CT head scan?

For your CT scan, you will lie
​on a table inside the CT machine.

During the scan, you might receive contrast (X-ray dye). Contrast is a substance that makes tissues and blood vessels easy to see in the CT pictures. If you receive contrast, it will be injected into your arm vein through an intravenous (IV) tube.

During the scan, you will lie inside the CT machine. Many X-ray beams will be passed through your head as the X-ray tube revolves around you.

The machine will take pictures from many angles, forming cross-section images (slices) of your head. Your doctor will review the pictures on a computer.

How should I prepare?

  • Wear comfortable, loose-fitting clothing on the day of your scan.
  • It is OK to eat a light meal before your CT scan. Drink plenty of fluids on the day of your scan.
  • Keep taking your regular medicines prescribed by your doctor. 

A CT image of the head

Before the Scan Begins

  • Women: If there is a chance you may be pregnant, tell the CT technologist before the scan begins.
  • Some items can affect the CT images. We may ask you to remove:
    • Any clothing with zippers or snaps
    • Hairpins, jewelry, glasses, hearing aids, and removable dental work
  • If you will have contrast for your scan, we will place an IV tube into your arm vein. This will be done before you enter the scanning room.

If You Will Receive Contrast

Before your scan, the CT technologist will ask you if you:

  • Are allergic to any medicines or iodine. Many types of contrast contain iodine. If you have had an allergic reaction to contrast in the past, we will ask you to take medicine to prevent a reaction to the contrast before your scan.
  • Have asthma, diabetes, a heart problem, multiple myeloma, or kidney disease. These health conditions may increase your risk of having a reaction to the contrast. For example, kidney disease makes it harder for your body to remove the contrast from your bloodstream.

Can a family member or friend stay with me during the scan?

  • Because CT uses X-rays, you may not have a family member or friend in the CT room during the exam.
  • For young patients, a parent may be able to stay in the room with their child to help reduce fear and provide comfort. The parent will need to wear a lead apron to limit exposure to the radiation used in the scan.

How is the scan done?

  • You will lie on your back on the CT table. The technologist will help you place your head in a special head-holder. This device uses soft straps to keep your head and neck in the proper position.
  • The technologist will then leave the room. You will be alone in the room during the scan, but the technologist can see, hear, and speak with you through an intercom at all times.
  • You will need to hold still while the table is moved into the center of the scanner. You will also need to hold still when the scans are being done so that we can get clear images.
  • For the first few scans, the table will move quickly through the scanner. These first scans check the correct starting position. The table will move more slowly for the rest of the scans.
  • If you are having contrast, it will be given to you through your IV at this time.
  • Afterward, the technologist will review the pictures. More scans will be done, if needed.
  • CT exam of the head and brain can take between 2 and 20 minutes.

What will I feel during the scan?

CT scans are painless. You may feel some discomfort from having to stay still.

If contrast is used:

  • You may feel discomfort at the injection site.
  • You may notice a warm, flushed feeling when the contrast is injected. You may also notice a metallic taste in your mouth. These reactions are normal. They should go away within 1 to 2 minutes.
  • Once in a while, a patient gets itching and hives for up to a few hours after receiving contrast. Tell us if this happens to you and we will give you medicine to treat the symptoms.
  • If you start to feel light-headed or short of breath, tell us right away. You may be having an allergic reaction to the contrast. A doctor or nurse will be nearby during the scan to help you, if needed.

What should I do after the scan?

If you received contrast, it is important to drink a lot of fluids after your scan. This will help your kidneys flush the contrast from your body.

Who interprets the results and how do I get them?

A radiologist skilled in reading CT scans will review and interpret your CT images. The radiologist will not talk with you about the results.  The radiologist will send a detailed report to your provider who referred you for the scan. Your own provider will talk with you the results of your scan.

You may also read your results on your eCare Results page. If you need copies of your images on disc, call 206.598.6206.

You and your provider will decide the next step, such as treatment for a problem, as needed.


Your questions are important. Call your doctor or healthcare provider if you have questions or concerns.

  • UWMC Imaging Services: 206.598.6200
  • UW Roosevelt Radiology: 206.598.6868
  • Harborview Imaging Services: 206.744.3105