For your CT scan you will usually be required to lie flat on your back for around 10 minutes. The scanner is a ring shape and the table you are lying on will move through the machine several times to get all the information needed. Unlike an MRI, the CT does not surround your whole body so should not be a problem if you are claustrophobic.
If you are having a contrast injection with your scan, someone will place a small tube called a cannula into your arm. The contrast injection will happen mid-way through your scan and you will be told before this happens. Contrast works a dye that goes into your blood stream and is absorbed, which helps distinguish between different structures. There is a small risk of allergic reaction when given the contrast injection, someone will explain this to your before your scan. Not everyone will need this injection.
The radiographer will operate the scanner from the control room next door, however, will be able to speak to you during you scan via an intercom. You will need to lie very still during your scan and may be given different breathing instructions to breathe in, breathe out or hold your breath.
If you have a contrast injection you may feel the liquid going up your arm however it should not be painful.