What is CT scanning?
CT stands for Computed Tomography and is a method of examining body organs using X-rays and a computer to construct a series of cross-sectional scans to form 2D and 3D imaging.
A CT scanner is an X-ray tube and an X-ray detector housed in a gantry shaped like a giant ring. The X-ray tube and the detector move around in a circle; when X-rays are emitted they are received by the detector and converted into a two dimensional image. This image can be reconstructed to produce virtual 3D images.
CT scans can be performed on any part of the body. They are very useful because they can demonstrate several kinds of body tissue (lung, bone, soft tissue and blood vessels) with great clarity. Doctors who interpret the scans (Radiologists) are able to diagnose diseases such as cancer, heart and vascular disease, injuries and musculoskeletal disorders.
At St John & St Elizabeth Hospital we have a Toshiba Acquilion One Genesis Edition CT scanner that can acquire cross-sectional images of large areas of the body in a matter of seconds.
This allows routine scanning of the chest and abdomen in a single breath hold. The short scan time is beneficial for all patients but especially for elderly, paediatric, or critically ill patients, where the length of scanning was often problematic.
Because it provides detailed views of all types of tissue, CT is one of the best tools for studying the head, chest and abdomen.
CT can clearly show even very small bones, as well as surrounding tissues, muscle and blood vessels. This makes it invaluable in diagnosing and treating spinal problems and injuries to the hands, feet, and other skeletal structures.
CT angiography (CTA) is a technique used to visualize blood flow throughout the body. This minimally invasive technique is now widely used to assess the arteries; from those serving the brain to those bringing blood to the lungs, kidneys, and the arms and legs.
A full range of specialist applications installed on our CT scanner enable us to perform:
- Single breath-hold CT of the chest, abdomen and pelvis
- High resolution chest CT
- Spinal and Orthopaedic CT
- High resolution head CT – Brain, Sinuses, IAM’s, etc.
- CT angiography – all areas of the arterial system can be imaged.
- 3D multiplanar reconstruction – useful in head, body and orthopaedic scanning.
- Cardiac calcium scoring: A non-invasive scan of the heart that detects areas of calcification in the coronary arteries. The results of the scan are then used to assess the likelihood and degree of coronary artery disease.
- Coronary angiography: detailed examination of the coronary arteries and chambers of the heart using an intravenous injection of contrast media.
- Interventional CT: radio frequency ablations, denervations and pain management injections under CT guidance
- Virtual colonography: volume rendered and ‘fly through’ non-invasive examination of the large bowel.
About CT scanning
Depending on the part of your body being examined, a dye (contrast medium) may be used to make some tissues show up more clearly. These dyes are harmlessly removed from the blood by the kidney and passed out in the urine.
If you are having an abdominal or pelvic scan, you may be given a special fluid to drink up to 90 minutes before the scan. The fluid allows the bowel to show up more clearly on the scan.
The scanner is a large machine with a hole in the centre (like a ring). Only the part of your body inside the ring can be scanned. You will be asked to lie on a table that can slide in or out of the scanner.
Your radiographer will position the table so that the part of your body to be scanned is lying in the centre of the scanner. The table will move backwards or forwards very slowly. The X-ray unit will rotate around you to help produce images from all directions.
Your radiographer will operate the scanner from behind a window, and he or she will be able to see, hear, and speak to you during the procedure. It can take several minutes for each image to form and it’s important to lie very still during the process.
At certain points during the scan you may be asked to hold your breath or to swallow.
CT scans are commonly performed and generally safe. You will be exposed to some X-ray radiation. Level of exposure is about the same as you would receive naturally from the environment over three years. Pregnant women are advised not to have CT scans as there’s a risk the radiation may cause damage to the unborn child.
Complications from a CT scan test are uncommon. In rare cases, it’s possible to have an allergic reaction to the contrast injection. Medicines are available to treat any allergic reaction.
Your doctor will explain the benefits and risks of having a CT scan and will also discuss alternatives to the procedure.