There are many different possibilities to take a picture of your body. You may know already how to take a picture with a camera. This picture shows the outside of your body.
There are also some methods to take special pictures of the inside of your body. These pictures look very strange, but special doctors called radiologists understand them and get some important information about your disease.
Ultrasound is also called ultrasonography. It uses sound waves to build up a picture of the inside of the body. Ask your mum: Her doctor could already see a picture of you before you were born! And now your doctor needs to see a picture of your kidneys, your liver, or perhaps another organ. The radiologist will spread a clear gel over your skin and pass a microphone over your body. The sound waves bounce off the organs inside the body. The microphone picks the sound waves up and a computer turns the information into pictures. This doesn't hurt at all, but you may perhaps not like the gel on your body. A nurse will help you to wipe it off after the examination.
An X-ray machine looks like a giant camera and uses X-rays to take a picture of the chest and of the bones. This is also called a skeletal survey. The X-ray technician will help you to get into the best position for the x-ray. You can help by trying to hold very still. The X-ray technician will leave you alone for a short moment in order to press the button of the X-ray machine in a small room nearby. This is very quick. Please don’t move, before the X-ray technician tells you to do so. Perhaps you can take a look at the pictures. Your bones will look white.
Magnetic Resonance Imaging (MRI) is also sometimes called nuclear magnetic resonance imaging (NMRI) or magnetic resonance tomography (MRT). In short, you can say MRI scan. It uses powerful magnets - these black pieces which are drawn agains each other and can stick to most fridges. The magnets make the atoms in your body, extraordinarily small parts which you can't feel, move in exactly the same direction. This is like when you lign pencils up on a desk so they all point in the same direction. When the magnet is turned off, the atoms start moving in their own way and send out radio waves. A scanner detects these radio waves and a computer turns them into pictures of the inside of your body, especially the soft tissues. The radiologist has to go to a different room to operate the MRI scan, but you can hear him or her talk to you.
The whole thing is painless, but you may not like that it is quite noisy. Imagine Bob the Builder working with hundreds of friends inside of the machine. You will get a good ear protection like a real builder! You may also not like that it usually takes quite a long time. It is important to keep very still to get good pictures. Small children or those who can't keep still are normally given a medicine called anesthesia which makes them fall asleep and feel comfortable.
MRI scan is often combined with other medical imaging techniques such as computed tomography (CT) or X-rays. Unlike CT scans or traditional X-rays, MRI uses no ionizing radiation (X-rays).
CT Scan or CAT Scan
A Computerised Tomography, in short CT scan or CAT scan, takes a number of X-ray pictures of the body from different angles. A computer turns them in pictures of ‘slices’ of your body. Depending on how big the part of the body is which must be scanned this can take between a few seconds and a few minutes. CT scans are painless. You need to remain still while the scan takes place. Therefore, small children may get a medicine which makes them feel comfortable for this short time. The radiologist has to go to a different room to operate the CT scan, but you can hear him or her talk to you.
Positron emission tomography, in short PET scan, produces a picture of functional processes in your body. This means it shows, how things work inside of you. You get a tracer which is a drug called 'positron-emitting radionuclide'. This tracer is "mixed" to a biologically active molecule, a substance which the inside of your body knows already because it is always there and moves all around. The tracer emits gamma rays. The PET machine detects these gamma rays and makes a three dimensional picture of it. The radiologist has to go to a different room to operate the PET scan, but you can hear him or her talk to you.
The molecule chosen for PET is often FDG. This is like a sugar in your body called glucose. When FDG is used, the scan is called FDG-PET. Sometimes other molecules are used to show different things.