CT
What is a CT Scan?
A CT scan uses X-Rays (radiation) and a computer to create detailed images of the inside of the body, within a single breath hold. A CT scanner is a ‘polo-mint’ shaped machine containing a bank of X-Ray tubes/detectors which spin around an axis in order to create 3D images through the body.
During a CT scan, you’ll usually lie on your back on a flat bed. The bank of X-Ray tubes/detectors rotates around your body, and you will be moved continuously through this rotating beam. The detectors pick up the X-Ray signals and produce an image of the body on the computer. A CT scan can produce images of structures inside the body, including the internal organs, blood vessels, bones and tumours.
The scan is painless and will usually take between ten and twenty minutes depending on the part of your body being scanned.
This video will show you what to expect when coming to the hospital for a CT scan.
How do I prepare for the test?
You will be given an appointment letter; please read this letter carefully as it will tell you which hospital your CT scan has been booked at and the time of your appointment.
It is advisable to attend wearing comfortable clothing, you may be asked to remove clothing which has any metal e.g., zips, belts, braces, and underwired bras.
How is a CT performed?
A CT scan is performed by a Radiographer; who is a specially trained Allied Healthcare Professionals and have expertise in radiographic technique and radiation protection.
Before having a CT scan, you’ll be asked about any previous scans, existing health conditions, whether you are taking any medication, and if you have any allergies. You may also be asked to remove some items of clothing or jewellery; including dentures of hearing aids, to ensure that these do not affect the images. The Radiographer will advise you which items to remove prior to your scan.
The Radiographer will operate the scanner from an adjoining room. While the scan is taking place, you’ll be able to hear and speak to them through an intercom. While each scan is being taken, you’ll need to lie very still and breathe normally. This ensures that the scan images aren’t blurred. You may be asked to breathe in, breathe out, or hold your breath at certain points.
The X-ray unit inside the ring will rotate around you. Each time it goes round it creates a new X-ray scan. The bed will move forward slightly after each scan is completed. Depending on the area of your body being investigated, a CT scan may last up to 20 minutes. You should be able to go home soon after the scan has been completed.
Tell the radiographer if you feel anxious or claustrophobic about having a CT scan. They’ll be able to give you advice to help you feel calm.
Contrast
Your scan may require an injection CT contrast. CT contrast is a liquid that shows up clearly on the images of certain tissues or blood vessels. It helps distinguish blood vessels from other structures in your body.
The CT contrast injection can make you feel warm all over your body and give you a metallic taste.
Contrast is usually harmless and will pass out of your body in your urine. In rare cases, contrast medium can cause an allergic reaction.
Tell the Radiographer if you have had an allergic reaction to iodine or contrast medium in the past, or if you have any other allergies.
