X-rays are produced in an x-ray tube in which high energy electrons are fired at a metal target whereupon they decelerate rapidly and transfer some of their kinetic energy to electromagnetic waves as x-rays.Only about 0.5% of the kinetic energy of the electrons is transfered in this way. The rest heat the target which maybe the anode of an x-ray tue of the glass of a t.v screen.
The beam of x-rays produced have a characteristic series of lines which are superimposed on a background of continous radiation.The beam is hardened to remove the low energy x-rays which would be absorbed by the patients body.
The accelerating potential required to produce x-rays is about 25KV to 400KV. Due to the heating effect the anode must be made of a material which has a high melting point and an efficient cooling system is required for it.The anode is typically made of tungsten which has a meting point of 3700K.
X-rays are used to visulaise certain body structure by passing a beam of x-rays through the body tissue to a photographic plate. Soft tissues do not scatter or absorb the radiation and appear as dark areas. Radio-opaque tissue such as bone aborb or scatter the tissue and they appear as a bright image on the radiograph.
To improve the diagnostic process a high radio-opaque such as barium sulphate can be introduced into the gastrointestinal tract before the x-ray is taken. The digestive tract will then show up clearly on the film as a well defined light region. Any obstructions will appear as a narrowing of a segment in the tract.The passage of the barium through the gastrointestinal tract can be be followed by repeated photographs. The rate of barium can then be determined and intestinal obstructions can be detected.
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