CT Scans

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Computed tomography (CT) or computed axial tomography (CAT) scanning is a special non-invasive x-ray test that produces cross-section images of the body. Special x-ray equipment combined with sophisticated computers produces multiple images of the inside of the body.
These are viewed on a computer monitor allowing manipulation of the data to create 3-D and multi-planar images. 64-slice CT technology makes use of 4x as many detectors as a typical multi-detector CT scanner. This results in much improved image quality with remarkable speed. Detailed pictures of any organ are produced in a few seconds thus reducing motion artefact.
This technology has allowed special investigations such as coronary CT to image the coronary arteries of the heart and CT colonography or virtual colonography.
Patient Q & A
Why is a CT Scan requested?

CT defines normal and abnormal structures and is also used as guidance for certain procedure such as biopsy, placement of drains and infiltrations.  Specific indications for a CT scan can be obtained under the heading of interest.

Are there any risks to undergoing CT?

Iodinated contrast material is often used to opacify blood vessels and other abnormalities. The patient must thus notify the department of any allergies to Penicillin or sea food/iodine before contrast is injected. Specific medications can be prescribed to prevent an adverse reaction.

The contrast is excreted via the kidneys.  In the elderly or in those with kidney dysfunction, a blood test to assess kidney function is required as iodine can adversely affect the kidneys. Please arrange to have a urea and creatinine done the day before the study. As a CT scan involves radiation, female patients must notify us of possible pregnancy.

What is going to happen?

Patients are usually scanned on their backs but sometimes other positions are adopted. The scans are fast and the patient does not lie in a tunnel as with MRI. The procedure is painless other than a small needle prick when contrast is injected. When iodine contrast material is used, it is not uncommon to get a metallic taste in your mouth and experience a ‘hot flush.’ This rapidly disappears.

The Radiologist is equipped to manage any adverse contrast reaction. The needle will be removed after the scan is completed. Results will be available the same day.

Brain and CTA

A CT scan of the brain is the most common investigation in the setting of trauma. Bleeding is detected which may require neurosurgical intervention.
Non-traumatic causes of bleeds are also best assessed by CT.
A CT scan can be done with iodinated contrast material to look for infection or tumours.
High definition scans will detect skull and facial bone fractures and sinus disease.
A CTA (CT angiogram)  is a special investigation to evaluate the intracranial vessels. Typically we would be looking for aneurysms or other vascular abnormalities.


CT Chest

A CT scan of the chest is commonly done following an abnormal chest x-ray finding.

Intravenous contrast material is often used to better delineate the anatomy and look for abnormalities.


  • To evaluate tumours of the pleura, lung and mediastinum.
  • Pulmonary embolism (clots in the lung) is detected using CT.
  • Interstitial lung disease (i.e. pulmonary fibrosis) is best demonstrated using high resolution scanning techniques (HRCT).
  • Lung infections (abscess) and empyema (infected pleural fluid) can be imaged.
  • Fractures of the ribs and sternum are easily seen on CT.


CT Colonography

This is a minimally invasive procedure to detect colorectal polyps and cancers.
It is indicated for those who are unable or unwilling to undergo conventional colonoscopy.
No sedation is required.
Bowel preparation is necessary to avoid false results from faecal residue. Diet requirements together with a purgative will be explained to the patient at the time of booking. Carbon dioxide is pumped into the colon per rectum during the procedure. This is to distend the bowel somewhat. Abdominal discomfort is managed with an anti-spasmodic.
The investigation does expose you to radiation.
No intravenous contrast is used.
This procedure does not allow for biopsy or polypectomy.


CT Peripherals

Iodinated contrast material is used to opacify the vessels which can then be imaged and displayed in 3-D.
This can be done in trauma patients where vascular injury is suspected or to evaluate the extent of peripheral vascular disease (atherosclerosis).

CT Spine

  • A CT scan is a very sensitive investigation for assessing the bony structures.
  • 3-D images can be obtained.
  • This investigation is commonly done in the trauma setting.


CT ABDO and Pelvis


  • Unexplained abdominal pain, weight loss and abdominal swelling are commonly investigated by CT.
  • An abnormality which was previously noted clinically or on ultrasound may be submitted for CT evaluation due to its cross-sectional imaging ability.
  • Renal tract stones are easily detected on CT.
  • Complications of surgery can be evaluated and sometimes managed.
  • Oral contrast material is often used to opacify the bowel which will be obtained from the department when the scan is booked. Detailed instructions will be given to the patient. Sometimes it may be necessary to place contrast in the rectum using a catheter.
  • Intravenous contrast material is usually used to more accurately evaluate the abdomen and detect abnormalities.


CT Coronaries

64-slice CT technology allows imaging of the coronary arteries.
Special scanning techniques allow imaging of the heart during the split second that the heart is not beating to eliminate motion artefact
Iodinated contrast material is used.
This investigation is non-invasive and used to detect coronary artery disease in those with abnormal clinical or ECG changes.
This technique does not allow for intervention such as stenting/balloon dilatation which will require formal angiography.
Special precautions
  • No caffeine 24 hours prior to study
  • No stimulant drinks such as Red Bull
  • Only rooibos tea permitted
  • Avoid peas and bananas
  • No Viagra 24 hours before

Continue with usual medication but avoid Metformin if diabetic.