What We Do

A computed tomography (CT) scan uses X-rays to make detailed pictures of structures inside the body. The CT scanner sends x-rays through the body area being studied. Each rotation of the scanner takes less than a second and provides a picture of a thin slice of the organ or area of interest. A CT scan can be used to study all parts of your body such as the chest, abdomen, pelvis and head. It can take pictures of body organs such as the liver, kidneys, pancreas and lungs. It can also study blood vessels, bones and the spinal cord.

 Materials and Resources to Help You

Resources from the Patient & Family Education Program

Visit our Health Information section to find dedicated resources to help you understand your condition. Find the information you're looking for.​

 Your Procedure

How to Prepare

If you have diabetes or kidney disease, your blood work should include a serum creatinine test. Your doctor should make sure that you have had blood work done no more than 3 months before your CT scan.

If you haven't had a blood test done recently, or if your blood work doesn't have the information we need, the receptionist or technologist may ask you to return to your clinic or your referring physician to arrange for a blood test. Your CT scan will be rebooked accordingly.

If you're having a CT scan of the abdomen, do not eat or drink 4 hours before your appointment. We might ask you to drink barium or water one hour before the procedure. Barium is a liquid that makes your stomach and intestines show up in the scan. It's important to follow the drinking instructions carefully.

For some CT scans, we might also inject you with a contrast. We'll put a needle in a vein in your arm or hand right before the scan to inject the contrast, which makes your blood vessels show up on the scan and can provide more information for the radiologist.

If you've had a previous contrast reaction, you'll need pre-medication and your referring doctor will have to give you a prescription. Please take the medication according to the instructions for your own safety.

If you're having a biopsy, you may have to do some special preparations. You'll get instructions from your doctor, and the clerical staff who book your appointment at the hospital. Call the hospital if you have questions about what to do before or after your biopsy. Our contact information is as follows:

Toronto General Hospital Medical Imaging CT Bookings Office
Monday – Friday
8:00 am – 3:45 pm
416 340 3384

Toronto Western Hospital Medical Imaging CT/Interventional Bookings Office
Monday – Friday
8:00 am – 4:00 pm
416 603 5800 ext. 5249

Checking In

When you come in for your CT scan:

Don't wear jewellery (or be prepared to take it off for the scan). If we are scanning you above the neck, you may also have to take off your dentures, hearing aids or hairpins or wigs.

Try to bring someone with you. If you're having a CT-guided biopsy, you'll need someone to help you get home afterward.

Bring a translator if you don't speak English or notify the hospital before your appointment so that we can make arrangements for a translator to be available.

It's important to arrive on time. If you are more than 15 minutes late, we may need to reschedule your appointment.

When you arrive at the Medical Imaging Department, check in at the reception desk. The receptionist may ask you:

  • For your health card (OHIP card). If you do not have an OHIP card, please bring another form of government-issued photo ID (such as a driver's license, passport or other provincial health card). Please arrive 15 minutes before your appointment.
  • Your name, address and birth date
  • Completed Requisition form if not booked online

At TGH the receptionist will then send you to the CT assistant's desk. At TWH patients are asked to wait in the main waiting room. The technologist will pick them up and bring them to the sub-waiting room in preparation for the CT scan.

You will be asked:

  • If you have had a CT scan before
  • If you have had a reaction to IV contrast
  • If you have diabetes or a history of kidney disease

If you have diabetes or a history of kidney disease, we'll need the results of a serum creatinine test that's no older than 3 months. Contact your doctor if you have not had a recent serum creatinine test. If we don't have these results on the day of your appointment, we may need to rebook your CT scan for your safety.

If you are taking oral diabetes medication containing metformin (such as Avandamet, Glucophage, Glucovance, Glumetza, Glycon, Metaglip or Riomet), you may need to stop taking your medication for 48 hours after being injected with the IV contrast. A technologist will inform you if you need to stop taking your medication. You should drink lots of water after your scan. Call your referring doctor if you notice a change in how much you urinate before restarting your medication.

Before the CT Scan

You will be given a name band to wear on your wrist if you are receiving IV contrast. You will be asked to read a medical history sheet and check off anything that applies. If you are here for an abdominal CT scan, you may be given a barium drink that needs to be finished within an hour in another waiting room.

You will then be asked to change into a gown and to keep all valuables with you. When you have finished changing, a technologist will ask for your name and take you into the CT scan room. Then the technologist will confirm your identification, explain the procedure, provide you with time to ask questions and ask for your consent to the procedure.

Depending on the medical history provided by your referring physician, you may be given the IV contrast injection. When receiving the injection, you may feel a warm, flushed feeling throughout your body and the need to urinate. You may also notice an odd taste or smell. This is normal.

During and After the CT Scan

The technologist will connect your IV to a special pump, position you on the CT scan table and then go to the CT control area. It will take a few minutes for the technologist to start the scanner, and you'll hear some noise.

More importantly, you'll also hear instructions for your breathing. It's important to follow them in order for us to make clear, sharp images. If you're being injected with the contrast, the technologist will warn you when the injection starts.

After the scan, the technologist will give you a contrast reaction card, if you were injected. It is available in several languages. Some people may have a reaction to the contrast up to 7 days after the scan. If you notice any hives, itching or rash, please seek medical attention and take the contrast reaction card with you.

After the reaction has been treated, call the number on the card to have your reaction added to your electronic medical record. Tell us your name, your doctor's name and your MRN number (your hospital number on your blue hospital card).

Important: If you had to drink barium or if you were injected with the dye, drink lots of fluid over the next 24 hours to help flush this out of your body if your fluids are not restricted.

The Results of Your CT Scan

The technologist uploads your scan pictures to a computer database. Then a radiologist studies the images and writes the report, which will be attached to your electronic health record. Your doctor can then review it and share it with you.

Please understand that the technologist can't give you the results when your scan is finished.

How Long Will Your Appointment Be?

The length of your appointment will vary depending on what kind of CT scan you are having.

We do our best to stay on time. Unfortunately, your appointment may be delayed by unforeseen circumstances. We recommend that you come prepared for delays.​

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