What is a CT scan?
A computerised tomography (CT) scan, also known as a CAT scan, works by combining numerous X-ray images that are taken from different angles and processing them through a computer to produce a cross-sectional image of different parts of the body. CT scans can be used to take images of bones, blood vessels and soft tissues and provide much more detail than regular X-ray images.
What does a CT scan involve?
CT scans are carried out in just a few minutes, and can take up to 30 minutes to complete. During a CT scan, you lie down on a table that slides in and out of the CT machine. You rest your head on a pillow and you may be strapped to the table to help you stay in position. If your head is being scanned, a special head cradle might be used. Whilst you are being scanned, the CT scan technician stays in an adjacent room and will communicate with you via intercom. In some instances, you might be given a contrast dye which highlights certain tissues for the technician.
What is a CT scan for?
A CT scan is often used for diagnostic reasons, for example, they are used a lot when dealing with patients who have been injured and might have internal damage.
A CT scan is also used for the following:
- To locate a tumour or blood clot
- To guide procedures, such as surgery, biopsies or radiation treatment
- To diagnose bone and muscle disorders
- To determine if there is any internal bleeding present
- To check how effectively a treatment is working
- To examine conditions affecting the heart and its blood vessels (coronary CT scan)
How can you prepare for a CT scan?
It may be necessary to remove certain clothes and accessories before a CT scan, depending on which part of the body is being scanned. Usually you will have to avoid food and drink a few hours before having a CT scan.
What does it feel like during a CT scan?
A CT scan is painless; however, it usually requires you to remain very still, which can sometimes be challenging, particularly if the patient is a child or in pain. Movement can blur the images, so it is important to stay still during the scan. Sometimes the patient can be given a mild sedative to help them relax.
What happens with the results?
Once your scans are complete and the images are ready, the radiologist will write a report which is then shared with your doctor, who will discuss the results with you. Results can be processed either within a few days or a few weeks.