For most CT scans you can eat and drink normally. If your scan uses contrast dye, you'll usually be asked to skip food for about four hours beforehand but keep drinking water.

Keep taking your regular medications. If you take metformin for type 2 diabetes, mention it when you book. You may be asked to pause it for 48 hours after a contrast scan.

Wear something loose and comfortable, and avoid clothing with metal zips or underwire if you can.

The X-ray scan itself doesn't hurt. You won't feel the X-rays.

If you have contrast dye, you may notice a brief warm flush and a metallic taste. Some people get a passing sensation of needing to wee. These effects are common and pass in under a minute.

Yes. CAT, short for computed axial tomography, is the older name for the same test. Both terms describe the same scanner and the same kind of imaging.

Yes. CT scans need a referral from your GP or specialist. Bring the original on the day, or have a photo of it on your phone when you book.

Yes. CT scans don't use sedation, so you can drive, return to work, or carry on with whatever you had planned for the day.

CT uses X-rays and takes a few minutes. MRI uses magnets and takes 30 to 60 minutes inside an enclosed tunnel. CT scanners are short and open at both ends, which many people find more comfortable.

Tell us before your appointment if you're pregnant or think you might be. Your referring doctor and our radiologist will decide whether a CT is appropriate, or whether an ultrasound or MRI would be more suitable.

Yes. A partner, friend or family member is welcome in the waiting area. They cannot enter the scanning room because of the radiation, but they can be with you before and after.

CT scans use a small dose of ionising radiation. Your referring doctor will decide whether the diagnostic benefit is appropriate for your situation. Low-dose imaging protocols are used to keep exposure as small as practical.