What is Computed Tomography?

A Computed Tomography or CT scan is a special examination using x-rays and special computers to produce cross-sectional images of the body, giving detailed information for diagnosis. The advanced multislice CT equipment which is installed in our facilities is capable of giving high-resolution scans at very short scanning time. With advancement in technology, the data can be reconstructed in various planes to produce 3D images with surface rendering, virtual colonoscopy, angiography and cardiac coronary vessels.

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Preparations for Computed Tomography
  • Patient should fast for about four hours if intravenous contrast (a medication that enhances and better define blood vessels and accentuate the appearance between normal and abnormal tissue in organs) injection is required.
  • Please inform staff it you have any history of allergies.
  • Please be punctual for your appointment.

What are the benefits and risks?

  • Unlike other imaging methods, CT scanning offers detailed views of many types of tissue, including the lungs, bones, soft tissues and blood vessels.
  • CT scanning is painless, non invasive and accurate.
  • CT examinations are fast and simple. For example, in emergency cases, they can reveal internal injuries and bleeding quickly enough to help save lives.
  • CT scanning can identity both normal and abnormal structures, making it a useful tool to guide radiotherapy, needle biopsies and other minimally invasive procedures.
  • CT has been shown to be a cost-effective imaging tool for a wide range of clinical problems.

  • The effective radiation dose from this procedure is about 0.01 mSv, which is about the same as the average person receives from background radiation in one day.
  • Women should always inform the radiographer if there is any possibility that they are pregnant.

What are the limitations of a CT Scan?
  • CT does involve exposure to radiation in the form of y-ray, but the benefit of an accurate diagnosis far outweighs the risk. The effective radiation dose from this procedure is about 10 mSv, which is about the same as the average person receives from background radiation in three years.
  • Women should always inform their doctor or nurse or radiographer if there is any possibility that they are pregnant.
  • Nursing mothers should wait for 24 hours after contrast material injection before resuming breast feeding.
  • The risk of serious allergic reaction to iodine-containing contrast material is 1%.
  • The risk of extravasation where injury to blood vessel causes leakage of contrast to surrounding tissues is 0.1% or 1 in 1,000.

On the Day of the Examination

  • You will be asked if you have any history of allergies and kidney functions.
  • Informed consent will be obtained If intravenous contrast is required.
  • If the CT is to examine your abdomen, you will be asked to swallow a liquid contrast material that will enable better visualization of the stomach and bowels. It may be necessary for you to wait while the contrast material reaches the bowels. If the lower bowels are to be studies, we may require to administer contrast material by enema.
  • An intravenous injection line may be set up in preparation of the intravenous injection.

During the Examination
  • You will be positioned on a padded table and moved into the scanner.
  • The radiographer will be able to see and hear you at all times.
  • You will be intermittently asked to stop breathing. It is important to follow the instructions given in order to ensure that the examination is successful.
  • If the intravenous injection is given, a warm sensation will be felt as the injection goes through the body. Some people report feeling a flush of heat or a metallic taste at the back of the mouth. These sensations usually disappear within a minute or two.

How long will it take?

Depending on the parts to be examined, the total examination from preparation could be from 15 mins to 90 mins.

When you can expect results

Images will be reviewed by the radiologist to check that they are clear. The report will be sent to your doctor who will then discuss the scan results with you.

For further information, please consult your doctor or call our staff for assistance.


Radiology Department,
Gleneagles Hospital

6A Napier Road
Singapore 258500
Tel: (65) 6470 5730
Fax: (65) 6470 5749

Radiology Department,
Mount Elizabeth Hospital

3 Mount Elizabeth, Level 2 
Singapore 228510
Tel: (65) 6731 2100
Fax: (65) 6732 3368

Radiology Department,
Mount Elizabeth Novena Hospital 

38 Irrawady Road, Level 2
Singapore 329563 
Tel: (65) 6933 1188
Fax: (65) 6933 0526

Radiology Department,
Parkway East Hospital 
321 Joo Chiat Place
Singapore 427990 
Tel: (65) 6340 8714 
Fax: (65) 6340 8670

CT Centre, 
Mount Elizabeth Hospital 

3 Mount Elizabeth, 
2nd Level
Singapore 228510 
Tel: (65) 6731 2727 
Fax: (65) 6238 0764
For more information, please visit our FAQ (Frequently Asked Questions) page.