The aim of imaging is to provide detailed and reliable pictorial information about structures within the body with the minimum risk and discomfort. Most imaging is now highly computerized and has largely replaced exploratory surgery in establishing the presence and extent of disease. Recent techniques are also able to indicate how well a tissue or an organ is functioning.
The first techniques used for imaging the body were based on X-rays, a form of high-energy radiation that is able to pass through body tissues. Some X-rays require particular substances, called contrast media, to improve the visibility of certain structures.
Over the last 40–50 years, many new techniques have been introduced, most of which involve the use of computers that control the imaging equipment and are able to create images of the body in three dimensions.
This section begins by explaining the basic imaging methods that use X-rays, which include ordinary and contrast X-rays and CT scanning. Other imaging techniques are then covered, such as MRI and ultrasound scanning, which do not involve the use of radiation, and different types of radionuclide scanning.
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.