Imaging techniques
Imaging techniques are ways in which doctors can create detailed pictures of what's going on in our bodies without having to open us up.
X-rays
X-rays are a form of electromagnetic radiation that can be used to take photographs of the inside of your body. X-rays are absorbed by dense materials inside the body, such as cartilage and bone, but not by lighter substances like blood.
Cancers and other abnormal growths often show up as a 'shadow' on an x-ray photograph. A breast x-ray is often called a mammogram, and is the mainstay of breast cancer screening.
CT scans
A CT scan (or CAT scan as it is sometimes called) is a way of taking lots of different x-ray photos of your body from different angles. These are then put back together using a powerful computer to form a 3D image or a series of pictures of 'slices' through your body. This allows doctors to see exactly where a tumour may be, and what organs it is close to.
CT scans can also be a huge help in planning surgery or radiotherapy.
You can find out more about CT scans on our patient information website, CancerHelp UK.
MRI scans
Magnetic Resonance Imaging, or MRI, uses magnetism rather than x-rays to build up a picture of the insides of your body. In an MRI scanner, the body is exposed to a magnetic field about 20,000 times stronger than the earth's. This causes the atoms that make up your body to vibrate slightly, although the procedure is completely painless. These vibrations release radio waves that are picked up by the scanner.
By analysing these signals, doctors can construct a picture of your insides.
MRI scans can be used like a CT scan (see above) to view 'slices' through the body, or can make 3D images of your organs. It usually produces a more detailed view of the body than x-rays can, so doctors often use MRI to examine your head and brain. It can also be used to measure blood flow.
You can find out more about MRI scans on our patient information website, CancerHelp UK.
PET scans
Positron Emission Tomography (PET) is a very new technology and is only available in a few hospitals in the UK. The patient is injected with a tiny amount of a special tracer material that releases sub-atomic particles called positrons.
When positrons collide with the atoms of the body, they release tiny bursts of energy. The patient is then placed in a scanner that picks up these energy bursts and builds a picture based on where the tracer has travelled in the body.
PET scans can be even more sensitive type of scan than MRI and x-rays (see above). They can show how a particular bit of your body is working, not just what it looks like. For example, a PET scan can show whether the tissue remaining after treatment is living cancer or just dead tissue. Cancer Research UK has been leading the way in developing PET in Europe.
You can find out more about PET scans on our patient information website, CancerHelp UK.
Ultrasound
Ultrasound scans use sound waves to build up a picture of the inside of your body. A tiny speaker emits sound waves, which bounce off your internal organs, and a microphone picks up the reflections. This is connected to a computer, which converts the sound waves into a picture.
You can find out more about ultrasound on our patient information website, CancerHelp UK.
