Before you have a CT scan, you will be asked a few questions about your health. This may concern whether you have any existing health conditions, whether you are taking any medication, whether you have any allergies and whether you are pregnant (if you are a woman of childbearing age). You will be asked these questions to minimise the chance of side-effects or reactions during the scan.
If you are nervous, worried or even suffer from claustrophobia, you can talk to the radiographer who will be operating the CT scanner. Your radiographer can answer any questions you may have, help to calm you down and feel relaxed and offer advice if you feel claustrophobic. If you are really struggling, they may advise you to have a sedative.
Getting ready for the scan
Before you have your scan you will be asked to undress and put on a gown. You will also be asked to remove any jewellery and anything with metal fastenings, as this will affect the scan images. If you are having a scan on your head, you may be asked to remove glasses, earrings or other piercings, hair clips, dentures, contact lenses and hearing aids.
Once you are ready for the scan, you will be asked to lie on the motorised bed. The radiographer will adjust the position of the bed to ensure that the correct part of the body is scanned, and they will only begin the scan when you are ready.
Contrast medium
In some cases, patients are given a contrast medium to make the images clearer. The contrast medium is a dye, which shows up on the scan images. Contrast medium is used only in some scans, as it helps doctors to distinguish between the blood vessels and other structures inside the body.
The contrast medium can be injected, swallowed or given as an enema. It is usually very safe but in extremely rare cases it can trigger an allergic reaction. Sometimes, people say that having the contrast medium injection can make them feel like they need to urinate, however, this sensation is completely normal and usually subsides very quickly.
During the scan
Once you are ready for your scan, the radiographer will leave the room, in order to protect themselves from exposure to radiation. If they were to stay in the room during the amount of CT scans they perform on a daily basis, then this would leave them exposed far too much. You will still be able to hear the radiographer and you can talk to them if you need to. During the scan, the motorised bed will move into the scanner and the X-ray scanner will rotate around you. As it moves you will be asked to remain as still as possible to prevent the images being blurred. The radiographer may ask you to breathe in, breathe out or hold your breath at certain points during the scan.
The bed will continue to move and X-rays will be taken as you move through the scanner, with the procedure taking up to 30 minutes. Sometimes, spiral CT scans are used (these are also known as helical scans), which are much faster than standard CT scans and can produce images in a matter of minutes.
After the scan
After the scan you should be able to go home straight away. Your results will not be available immediately and they will be sent to your doctor, who may either be your GP or your specialist. You can ask how long your results will take before you leave the hospital but, in most cases, they take around two weeks.