Visualizing internal organs
Modern technological advances have changed the way in which we investigate the human body, and today a wide variety of visualizing techniques is available. Imaging creates pictures, usually on film or a computer, of internal organs and structures. Viewing techniques use specialized devices, including endoscopes, to allow hollow structures in parts of the body such as the digestive tract to be looked at directly.
Imaging and viewing techniques are often used to confirm a diagnosis or to make one if other tests are not conclusive. These techniques may also be used to screen for some disorders and to monitor the progress of a disease or treatment.
Most imaging techniques, and some complex viewing techniques, are carried out in hospital. Other techniques, such as simple X-rays and basic viewing, may be performed in the doctor's surgery or an outpatient clinic.
Imaging uses modern technology to create a picture of internal organs or body structures. The oldest form of imaging, which is still in use today, consists of “shadow pictures”, mainly of the skeleton, cast by X-ray radiation on to photographic film.
Since the 1940s, there have been major advances in the field of medical imaging. Today, advanced techniques such as CT scanning use X-rays to produce detailed images of soft tissues and structures other than the skeleton. Liquids called contrast media can also be introduced into structures, such as blood vessels, enabling hollow areas or fluid-filled structures to be seen using X-rays. Radionuclide scanning detects the radiation emitted by radioactive substances that are introduced into the body, allowing doctors to assess cell activity in body tissues.
Other modern techniques include MRI, which uses radio waves and magnets to produce clear, detailed images, and ultrasound scanning, which uses sound waves. Both of these techniques do not use radiation.
Some scanning techniques, such as spiral CT scanning, are so advanced that a computer can create a video image that gives an impression of travelling through parts of the body.
Depending on the problem, a direct view of part of the body sometimes provides more useful information than an artificial picture created by an imaging technique. Structures near the surface of the body, such as the eardrum, can be viewed directly using simple instruments. Endoscopes are used to look deeper inside the body.
Endoscopy was first used more than 100 years ago, when short, rigid devices were used to look inside the bladder and the colon. Today, rigid endoscopes are still used to view some body cavities and to carry out certain types of surgery. However, advances in technology have also led to the development of a range of flexible endoscopes. These endoscopes are used to examine the internal walls of hollow structures that can be reached through natural body openings. For example, the upper digestive tract may be viewed through the mouth.
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