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The Epic Interactive Encyclopedia 1998
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Epic Interactive Encyclopedia, The - 1998 Edition (1998)(Epic Marketing).iso
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Radiotherapy
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INFOTEXT
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1992-09-02
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Treatment of disease by radiation from X-ray
machines or radioactive sources. Radiation,
which reduces the activity of dividing cells,
is of special value for its effect on
malignant tissues, certain nonmalignant
tumours, and some diseases of the skin.
Generally speaking, the rays of the
diagnostic X-ray machine are not penetrating
enough to be efficient in treatment, so for
this purpose more powerful machines are
required, operating from 10,000 to over 30
million volts. The lower-voltage machines are
similar to conventional X-ray machines; the
higher-voltage ones may be of special design;
for example, linear accelerators and
betatrons. Much radiation now given uses
synthesized radio isotopes. Radioactive
cobalt is the most useful, since it produces
gamma rays (highly penetrating), and it is
used instead of very high- energy X-rays.
Similarly, certain radioactive substances may
be administered to patients; for example,
radioactive iodine for thyroid disease.
Radium, formerly widely used for
radiotherapy, has now been supplanted by more
easily obtainable, artificially produced
substances.