CT scan and cancer diagnosis

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CT scans take a series of images that help the health-care team diagnose the type of cancer you may have. Find out how CT scans are done, what you need to do to prepare and what to expect when you get your results.

Key points

  • CT scans take a series of pictures that are then put together so the doctors can see different "slices" through your body.
  • You will need to remove any metal before a CT scan, change into a hospital gown and lie completely still during the scan.
  • A CT scan usually takes about 30 minutes.
  • You may need to drink or have an injection of contrast dye that will make the CT pictures clearer.
  • It may take up to a week before your get the results of the scan.

What is a CT scan?

CT stands for computed tomography. CT scans take a series of X-ray pictures as the scanner moves down your body. Then a computer puts all the X-ray pictures together and the doctors can see different representing "slices" through your body.

A CT scan can take a picture of any body part. The pictures are clearer than regular X-rays and it is easier to see all the different little parts inside the body.

CT scans are used often and are considered safe. Some people worry about radiation from the X-ray camera in a CT scan. If you or your family have questions or are concerned about radiation, talk to your doctor or nurse.

How are CT scans done?

The CT scan machine looks like a giant donut. You will lie on a narrow bed that slides into the centre of the donut. You will hear some noise as the camera moves around inside the donut to take X-ray pictures from many different angles.

A technologist will show you what to do during your CT scan. You will probably need to change into a hospital gown and you will need to take off any metal you are wearing because it can cause problems with the picture.

During the scan, you will need to stay completely still. The technologist will leave the room, but you will still be able to hear and talk to them over an intercom.

If you are worried about being inside the machine or that you will not be able to stay still, talk to your doctor before the day of the scan. They can give you suggestions to help you through it or may be able to give you some medicine that will help you relax.

Usually, a CT scan takes about 30 minutes. The scan itself is usually pretty quick, but it can take a while to prepare the machine and help you get into the right position.


Sometimes you will need to drink or have an injection with a special dye called contrast that makes the CT scan pictures clearer. Some people say they feel warm or taste bananas or a metallic taste when the dye is in their body, but this sensation goes away.

CT scan results

A specialist doctor called a radiologist will look at the pictures from the CT scan and will then talk to your doctor. Your doctor will tell you and your family what the pictures showed. It can sometimes take up to a week for the results to be ready.

Last updated: September 3rd 2019