Computerised Tomography (CT) uses special x-ray equipment to obtain images from different angles around the body, then uses a computer to process the information to show a cross-section of body tissues and organs. It is a non-invasive procedure which provides detailed views of all types of tissue.
The CT scanner is a large square machine with a hole in the centre. The patient lies still on a table that can move up or down, and slide into and out from the centre of the hole. Within the machine an x-ray tube rotates around the patient’s body to produce the images.
As with x-rays, very small controlled amounts of radiation are passed through the body. The resulting images are then reconstructed by a computer into two-dimensional images of the sections that were scanned. This enables a very detailed, multidimensional view of the body’s interior.
Spiral or helical CT allows faster, higher-quality images with less radiation exposure.
CT scanning is painless. For some examinations of the abdomen you may be required to drink a contrast material prior to the examination. Other examinations may require an injection of intravenous contrast. You may be asked to refrain from eating or drinking anything for up to four hours prior to your examination. Other examinations require no preparation at all. You will be alone in the room during the examination, although the Technologist will be able to see and speak to you.
CT imaging of the lower gastro-intestinal (GI) tract can be used to accurately diagnose many causes of abdominal pain such as an abscess in the abdomen, tumours, diverticulitis and appendicitis. It is also used to detect kidney stones or tumours. CT is often the preferred method for diagnosing many different types of cancer, since it can confirm the presence of a tumour, measure it’s size, precise location and the extent of the tumours involvement with nearby tissue. CT examinations can also be used to plan and administer radiotherapy treatments for cancers, and to guide biopsies.
CT can assist in locating skull fractures and brain damage in patients with head injuries. It may be used to detect a blood clot or bleeding within the brain shortly after a patient exhibits symptoms of a stroke or in a patient with sudden severe headache who may have a ruptured or leaking aneurysm. CT is used to detect some brain tumours. CT is useful to determine whether inflammation or other changes are present in the paranasal sinuses.
CT Colonography is a procedure using a CT scanner and specialised computer software to obtain an interior view of the colon (large intestine).
The major reason for performing a CT colonography is to look for polyps and other lesions in the large intestine. Some polyps may grow and turn into cancers. The goal is to find these growths before they turn into cancers.
If you have heart disease or diabetes it is very important you tell us at the time of booking. Continue to take your essential medications.
It is very important to clean out your bowel for two nights before your examination so the Radiologist can clearly see any polyps that may be present.
You will be given a bowel preparation pack, which includes laxatives and a barium “tagging” mixture, along with a diet and instruction sheet. Please follow the instructions carefully.
You will be asked to undress and put on a gown. When you are ready the Medical Radiation Technologist will take you to the CT scanning room and will explain the procedure to you.
You may be given a small injection of Buscopan to relax the colon.
The Medical Radiation Technologist will position you on your left side on the scanner table. A small, flexible tube will be passed into your rectum to allow carbon dioxide gas to be gently pumped into the colon. The purpose of the carbon dioxide is to distend the colon as much as possible to eliminate any folds or wrinkles that might obscure polyps.
Once enough carbon dioxide has been pumped in you will be positioned on your back on the CT table. You will be asked to hold your breath for about 15 seconds while the first scan is performed. You will then be positioned on your front for a further scan.
Most patients report a feeling of fullness when the colon is inflated. The MRT will remain with you during this procedure but while the scan is performed he or she will leave the room. The MRT can see and hear you at all times.
The scanning procedure itself causes no pain or other symptoms. The entire procedure will take 15 to 20 minutes to complete.
When the examination is completed and the MRT has checked the scans to ensure all areas of your large intestine have be satisfactorily imaged you will be able to go to the toilet. You will then be able to get dressed and have a hot drink if you wish.
The carbon dioxide gas is absorbed by your body very quickly but you may feel full and may experience some mild cramping for a short time. Keeping moving by walking around will help to alleviate this discomfort.
You may resume your normal diet.
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