Computed Tomography (CT) Scan: About This Test

Skip to the navigation

What is it?

A computed tomography (CT) scan uses X-rays to make detailed pictures of parts of your body and the structures inside your body. During the test, you will lie on a table that is attached to the CT scanner. The CT scanner is a large doughnut-shaped machine.

Why is this test done?

Doctors use CT scans to study areas of the body, such as the brain, chest, or belly. CT scans are also used to assist or check on the success of a procedure or surgery. An example of this is when a CT is used to guide a needle into the body during a tissue biopsy.

How can you prepare for the test?

Talk to your doctor about all your health conditions before the test. For example, tell your doctor if:

  • You are or might be pregnant.
  • You are breastfeeding.
  • You have diabetes.
  • You take metformin.
  • You are allergic to any medicines.
  • You have had an X-ray test using barium contrast material in the past 4 days.
  • You get nervous in confined spaces. You may need medicine to help you relax.

What happens before the test?

  • You may be asked to take off your jewellery.
  • You will take off all or most of your clothes and then change into a gown.
  • If you do leave some clothes on, make sure you take everything out of your pockets.
  • You may have contrast materials (dye) put into an IV in your arm. In some cases, you may have to drink a contrast material. Contrast material helps doctors see specific organs, blood vessels, and most tumours.

What happens during the test?

  • You will lie on a table that is attached to the CT scanner.
  • The table slides into the round opening of the scanner. The table will move during the scan. The scanner moves within the doughnut-shaped casing around your body.
  • You will be asked to hold still during the scan. You may be asked to hold your breath for short periods.
  • You may be alone in the scanning room, but a technologist will be watching you through a window and talking with you during the test.

What else should you know about the test?

  • A CT scan does not hurt.
  • If a dye is used, you may feel a quick sting or pinch when the IV is started. The dye may make you feel warm and flushed and give you a metallic taste in your mouth. Some people feel sick to their stomach or get a headache.
  • If you breastfeed and are concerned about whether the dye used in this test is safe, talk to your doctor. Most experts believe that very little dye passes into breast milk and even less is passed on to the baby. But if you prefer, you can store some of your breast milk ahead of time and use it for a day or two after the test.
  • There is a small chance of getting cancer from some types of CT scans. The risk is higher in children, young adults, and people who have many radiation tests. If you are concerned about this risk, talk to your doctor about the benefits and risks of a CT scan and confirm that the test is needed.

How long does the test take?

  • The test will take about 30 to 60 minutes. Most of this time is spent getting ready for the scan. The actual test only takes a few seconds.

What happens after the test?

  • Depending on the reason for the test, you will probably be able to go home right away.
  • If contrast material was used, drink lots of liquids for 24 hours after the test unless your doctor tells you not to.

Follow-up care is a key part of your treatment and safety. Be sure to make and go to all appointments, and call your doctor or nurse call line if you are having problems. It's also a good idea to keep a list of the medicines you take. Ask your doctor when you can expect to have your test results.

Where can you learn more?

Go to https://www.healthwise.net/patientEd

Enter Q352 in the search box to learn more about "Computed Tomography (CT) Scan: About This Test."