Medical imaging

From ArticleWorld


Medical imaging is the process with the help of which physicians examine internal parts of the body using electromagnetic radiation. It is also known as diagnostic imaging as it aims at accurately diagnosing illnesses.

Medical imaging, as the name suggests, is used mainly for clinical purposes. It is also used for studying the internal working of living organisms. Techniques developed for medical imaging are also applied in other scientific fields and in factories.

Before medical imaging was introduced, physicians would only touch the patient and try to estimate the condition of the internal organs. This would help diagnose fractures and abnormalities in internal organs. This is necessary even today as an initial step in medical imaging, but it cannot be solely relied upon because interpretations can be inaccurate it cannot be recorded.

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Modern imaging technology

Radiography

Radiography employs the use of X rays for photographing internal organs. X rays, used since the late 19th century, are absorbed by denser body tissue like bones and pass through soft tissue. Bones show up as white areas in an X ray photograph. These photographs help in detecting the kind and degree of a fracture and also in detecting abnormalities in other internal organs.

Fluoroscopy

Fluoroscopy is a procedure that employs the use of an instrument called a fluoroscope in order to get real-time moving images of internal organs. It uses X rays and is similar to radiography, except that it provides continuous feedback.

Tomography

Tomography is a technique is which internal structures deep within the body are photographed using X rays or other radiation. There are three main types of tomography:

  1. Linear tomography: This is the most basic method. In this method, the X ray tube moves in one direction and the cassette holder (or film) moves in the opposite direction with the pivot point set to the part of the body under examination. This results in the blurring out of the objects in the body above and below the focal plane.
  2. Poly tomography or multidirectional tomography: This produces sharper images, but is more complicated. The X ray and film assembly are moved in any of the following geometrical movements: circular, elliptical, figure 8 and hypocycloidic.
  3. Computed tomography (CT): A CT scan, also known as a Computed Axial tomography (CAT) scan, is a widely used method in which a 2D image of structures is recorded on a radiation detector.

Magnetic resonance imaging (MRI)

This imaging technique, through the use of powerful magnets, obtains 2D images of soft tissues in the body like joints and the brain. Introduced in the 1980s, MRI is a relatively new technique.

Ultrasound

This imaging technique uses high frequency sound waves (between 2 to 10 MHz) that are reflected differentially by tissue to produce 2D images on a television screen. Ultrasound is used for examining foetuses in wombs, abdominal organs the heart and some other internal organs.