Explanation

CT scans are a way for doctors to diagnose certain problems and illnesses. CT stands for computed tomography. You might also hear them called CAT (computed axial tomography) scans.

CT scans are like more detailed x-rays. They use x-rays, but they are different because they can see LOTS more. CT scans can be done on any part of your head or body, and they can show things that x-rays can't, like your internal organs (like your liver, kidneys, brain and pancreas), muscles and blood vessels .

CT scans give your doctors a clear and detailed picture of what is happening. As well as using this information to help them find out what's wrong with you, they can also use it to help them decide what treatment to give you.

Why do I need one?

If your doctor thinks you might have an infection or an abscess, you will have a CT scan to help him or her to find it! CT scans can also help your doctor to diagnose inflammation in places like your liver, kidneys and lungs, and assess injuries to your bones. Doctors can also find tumours this way too.

If you are going to have surgery, CT scans can give the doctors a clear picture of the area they are going to operate on before they start.

CT scans are also used to show doctors EXACTLY where a tumour is, so that when they zap it with radiotherapy they can make sure they get a direct hit!

How does it work?

CT scans use x-rays and computers to take pictures of your body. The scan counts how many x-rays get through different parts of your body, and then makes a picture of what your body looks like!

CT scans are taken by a machine that looks like a giant donut! It is called a CT scanner . You lie down on a special bed, which passes through the donut while it spins around you like a dancer. Don't worry though - YOU don't spin, only the machine! You just have to lie still while it goes on around you!

Inside the scanner is an x-ray torch that shoots x-rays right through you, while an x-ray camera takes hundreds of pictures as it goes around. The pictures are black, white and grey, and the scanner uses a computer to put them all together in one image. This helps to tell doctors what the problem inside you is and exactly where it is.

What happens?

Before you have the CT scan you will have to remove any metal objects from your body, like jewellery and hairclips. It's also a good idea not to wear clothes with things like metal zips or studs in when you are going for your scan. This is because metal can stop the scanning machine from doing its job properly.

Your doctor might tell you not to eat or drink for a few hours before your scan. You may also need to have an injection of a harmless dye to make the pictures come out clearer, for example if it is your brain that is being scanned.

It can take a few minutes to set up and get you comfortable on the bed, but then all you have to do is lie very still so the picture doesn't get blurry - just like when you stay still to have your photo taken.

Most CT scans last for about 10 to 15 minutes, although they can sometimes take longer, depending on which part of your body is being scanned. A lot of this time is spent actually setting up the scan though, the scan itself doesn't take that long - often even as little as 20 seconds!

The CT scanner will make some quiet noises while the pictures are being taken. You and the radiographer can actually talk to each other while you are having the scan, through a special microphone that is built into the scanner!

The great thing is that you can have your Mum and Dad with you the whole time that you have the scan. They will have to wear something called a lead apron to protect them from the x-rays, but they can stand right next to you. If your Mum is pregnant, the radiologist will tell her to stay out of the room though, because the x-rays could harm the baby in her tummy. But remember - you can still talk to her through the microphone!

You can have music played to you to help you relax while you are having the scan - you might even be able to watch a DVD!

Doctors called radiologists, who are CT scan experts, may come and check the pictures before the scan is finished. As soon as the scan is over, you will probably be able to go straight home.

Will it hurt?

CT scans are totally painless - you can't see or feel x-rays. If you need to have an injection of a harmless dye to make the pictures come out clearer, you will only feel a little prick and this will hardly hurt at all. You can even have some local anaesthetic cream on the area beforehand if you want to, just ask.

What happens next?

The radiologist will send a report of your scan to your doctor so that you can talk about the results at your next appointment.

You won't feel any after-effects from the scan so you can just do all the stuff you would normally do.

Is there anything else I need to know about CT scans?

The dye that is used in the injections to make the picture clearer has iodine in it and this can cause an allergic reaction, although this is VERY VERY rare.

If you have had an allergic reaction to iodine or any other dye in the past, or if you have any other allergies, or asthma, make sure you tell the radiologist before you have your CT scan.

The dye could cause some damage to your kidneys, but only if you already have very serious kidney problems.

What if I have any more questions?

If you have any other questions, you can ask your doctor, or chat to other people about having a CT scan in the Medikidz forums and virtual world, Mediland.