CT scans

What is a CT scan?

A CT scan stands for a computerized tomography scan. It is often referred to as viewing a slice of bread within a loaf, without cutting it up. It combines multiple X-ray images taken from different angles to generate cross-sectional views, or “slices” of your body. A CT scan can provide more information than a regular X-ray scan.

A CT scan allows doctors to see the bones, soft tissues, internal organs and blood vessels in your body. It can be performed on any part of your body, and allows doctors to diagnose diseases or examine internal injuries.

When do I need a CT scan?

Your doctor may order a CT scan to help:

  • Diagnose muscle and bone problems – such as bone fractures and tumors
  • Determine the location, size, and shape of a tumour
  • Locate a blood clot, infection or the presence of excess fluid
  • Study the blood vessels and other internal structures to check for abnormalities
  • Detect and access the extent of internal injuries and bleeding
  • Monitor and access the effectiveness of treatments such as radiotherapy and chemotherapy for cancer treatment

What happens during a CT scan?

You may be advised by your doctor not to eat or drink for a few hours before the CT scan. You may need to wear a hospital gown and remove any metal objects or jewelry. 

Sometimes, a contrast dye may be given to you either by mouth, by injection or by enema through the rectum. This contrast dye allows a clearer image of your blood vessels, intestines and other body systems on the resulting images. Inform your doctor if you have any known allergies to contrast material.

During the CT scan, you will lie down on your back on a flat bed that passes into the CT scanner, a machine shaped like a large doughnut. Unlike an MRI scan, a CT scan does not surround your whole body at once. As the bed slowly moves into the CT scanner, X-rays will rotate around you to capture images of your internal structures. It is normal to hear some buzzing or whirring noises.

It is important to lie still during the CT scan as movements can lead to blur images. You may be asked to hold your breath for a short period. You will be able to communicate with the radiographer or technologists via intercom. They will be able to hear and see you from another room.

How long does it take?

A CT scan is a painless procedure and depending on which body part is being scanned, a CT scan can last for a few minutes to half an hour. Typically, the whole procedure is completed within 30 minutes.

What to expect after a CT scan?

In most cases, you will be able to go home on the same day after a CT scan. You may be advised by the doctor to drink lots of fluids to flush out the contrast dye if you have ingested it before the procedure. After the CT scan, the images are sent to a radiologist for examination. Your doctor will follow-up with you on the results after a few days or a week.

Are there any risks involved in a CT scan?

A CT scan is a generally safe procedure associated with little risk. During a CT scan, you will be briefly exposed to ionizing radiation. Although CT scans expose you to more radiation than normal X-ray scans, the risk of developing cancer from CT scans is low and they have not proven to be harmful. Your doctor will weigh the risks and benefits before deciding if you need a scan. Talk to your doctor if you have any concerns.

Inform your doctor if you are pregnant. Although the radiation from a CT scan is unlikely to be harmful to your baby, your doctor may recommend a different diagnostic method such as ultrasound or MRI scans in order to minimise any risk.

Some people may be allergic to contrast material. The contrast is a special dye that may contain iodine. Most allergic reactions are mild and result in a rash or itchiness. In rare situations, allergic reactions may be serious. Inform your doctor if you have any adverse effects to the contrast material and your doctor may give you some allergy medication or steroids.