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Computed Tomography (CT)

What is computed tomography?

Computed tomography, commonly known as a CT or CAT scan, uses X-rays and computers to produce cross-sectional images – like slices in a loaf of bread – of the bones, blood vessels and soft tissue inside the body. The scan can reveal details of internal organs that cannot be seen by conventional X-rays.

Person getting a CT scan

Getting a CT scan: what to expect

Preparing for the test

Different tests require different preparations. It’s very important that patients follow the correct preparation instructions for the test to be performed properly. If you are scheduled to have a CT at Sunnybrook and are not sure how to prepare for it, please call 416-480-4336.

Generally we require that you do not eat for three hours before your test. But we encourage you to drink plenty of clear fluids (water, clear juice). This will help your kidneys filter out the iodine dye or contrast agent often used to make your inner structures and organs easier to see.

You may require blood tests beforehand to determine how well your kidneys are working – a process that will delay your scan by about 30-60 minutes but will ensure that it is safe for you to receive the contrast injection

On the day of the test

The test will take approximately 45 minutes to 2.5 hours, including time to prepare, depending on the procedure.

Please check-in for your appointment at the Bayview Campus (2075 Bayview Ave), A-wing, ground floor, room AG 256.

After check-in, a nurse will ask you a number of questions, including your medical history, current medications and any allergies you may have.

Depending on the type of scan, you may be instructed to drink a special and safe solution to prepare. The solution is a contrast agent (or “dye”) that will help the radiologist see the body structures on the CT image. In other cases, a contrast agent may be injected intravenously (through an IV) at the start of the test.

You may be asked to change into a hospital gown and remove any jewelry.

During the test

If you have an IV, the contrast agent will be injected into your veins. You may feel warm, feel like you have a metallic taste in your mouth or feel like you have to urinate. These are common reactions and will pass.

The technologist will help you lie in the correct position on the examining table. The table will then move through a large, doughnut-shaped scanning device. The tube rotates around you, taking many images of your body. It is very important that you lie as still as possible during the entire procedure so that your images come out clearly.

After the test

If you’ve been injected with the contrast agent, you will be monitored for 10 minutes before your IV is removed and you are able to leave the hospital.

Generally, you can resume your usual activities and regular diet immediately after the test. We encourage you to drink plenty of fluids for 24 to 48 hours to help clear the contrast agent from your system.

The results of your CT scan should be available to your referring physician in five to seven business days after your test. Your physician will discuss the test results with you.

Your report can also be accessed through MyChart in two to three weeks after your test.


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Location and contact

Computed Tomography (CT) Scan

Sunnybrook Health Sciences Centre
2075 Bayview Avenue, 
A-wing, ground floor, room AG 256
Toronto, ON M4N 3M5

Phone: 416-480-4336


Monday-Friday: 8:00 a.m. - 4:00 p.m. 

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