CT Technology

What is a CT scanner?

A Computerized Tomography (CT) scanner is a special kind of X-ray machine. The CT scanner was discovered by Sir Godfrey Hounsfield and Dr. Alan Cormack.
A CT Scanner sends several beams of X-Rays simultaneously from different angles to make detailed study of all parts of the body.

How does a CT scanner work?

A CT Scanner uses a series of X-ray beams to build up images of the body in slices. The CT scanner emits a succession of narrow beams of radiation as it moves through an arc. The X-ray detector within a CT scanner can see hundreds of different levels of density within the organs of the body including the tissues.

A computer uses this information to work out the relative density of the tissues examined and finally processes the results displaying them as a two dimensional picture on a monitor.

CT-Scan in Medical Treatments

CT Scans are far more detailed than ordinary X-Rays. The CT scanner is particularly good at testing for bleeding in the brain, for aneurysms, brain tumours and brain damage.

A CT Scan can study all parts of the body, such as the chest, abdomen, pelvis, or an arm or leg. It can also study blood vessels, bones and the spinal cord.
Fluoroscopy CT is a special test which allows the doctor to inspect the inside of the body without having to operate or perform unpleasant examinations.

Diagnostic Uses

CT Scans are mainly used to study the different areas of the body. A CT Scan of the chest (thorax) can identify problems within the lungs, heart, oesophagus, and the blood vessels or tissues in the chest. The common chest problems that CT Scans identify are lung cancer, pulmonary embolisms, and aneurysms.

A CT Scan of the abdomen can find cysts, abscesses, infection, tumours, bleeding in the abdomen, enlarged lymph nodes, appendicitis, as well as other abnormalities.

A CT Scan of the liver can find liver tumours, bleeding from the liver and liver diseases. A CT Scan of the liver can also help determine the cause of Jaundice.

A CT Scan of the kidneys can find kidney stones, bladder stones or blockage of the urinary tract.


A CT scan can look for problems within the organs of the pelvis. For a woman, these include the uterus, ovaries, and fallopian tubes. For a man, the pelvic organs include the prostate gland and the seminal vesicles.

Transmission Imaging

X-rays, Computer Tomography Scans (CT Scans) and fluoroscopy are radiological examinations whose images are produced by transmission.

A CT scan is a diagnostic imaging procedure that uses a combination of X-rays and computer technology to produce cross-sectional images both horizontally and vertically of the body. A CT scan shows detailed images of any part of the body, including the bones, muscles, fat, and organs.

Preparing a Patient for a CT scan

A CT Scan is usually done by a radiology technologist. The scan may need a contrast dye or substance that improves the picture of certain tissues or blood vessels. This material may be swallowed, given as an enema or injected into the blood stream, depending on the part of your body that is to be scanned.

If the patient is undergoing an abdominal scan, they will be asked not to eat for six hours before the test. The patient will be asked to remove any jewellery or metal fastenings that are in the area to be scanned.

During the scan the patient lies on a bed that is attached to the CT scanner, which is a large doughnut-shaped machine. The CT scanner sends X-rays through the patient’s body and the bed moves slowly backwards and forwards to allow the scanner to take pictures of the body. The length of the scan depends on the number of pictures taken at different angles.

What are the Risks of CT-Scans?

Doctors do not generally recommend CT Scans without a good medical reason as there is far more X-ray exposure than is involved in ordinary X-rays. Pregnant women should not have a CT scan as there is a small risk that X-rays may cause abnormality to the unborn child.

Nursing mothers should wait for 24 hours after a scan using a contrast dye before resuming breastfeeding.

The contrast dye used in CT Scans often contains iodine, which can cause allergic reaction in some patients.

Also, the dye may cause some kidney damage to people who already have kidney problems.

Although every effort is made to educate you on CT-Scan and take control, there will be specific information that will not be discussed. Talk to your doctor or health care provider about any concerns you have about CT-Scan.

Other Diagnostics

  • Royal Australasian College of Surgeons: RACS
  • Neurosurgical Society of Australasia
  • Australian Medical Association
  • Cancer Institute NSW
  • Cooperative Trials Group for Neuro-Oncology (COGNO)
  • Australia and New Zealand Melanoma Trials Group (ANZMTG)
  • Society for Neuro-Oncology
  • Sydney Catalyst
  • National Biobanking Consortium for Brain Cancer (NBCBC)
  • Melanoma Institute Australia
  • The University of Sydney
  • University of Notre Dame
  • Royal Prince Alfred Hospital
  • Chris O'Brien Lifehouse
  • Mater Hospital - Sydney