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An even greater radiation
hazard in veterinary radiography could occur during fluoroscopy. This is a
procedure in which the X-ray film is replaced by a special screen coated with
fluorescent zinc sulphide crystals, enabling the operator to see directly the
dynamic structure and internal anatomy of a patient, in a darkened room.
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It has
been used to save time and the expense of exposing and developing X-ray film and
also because it is a technically simple procedure.
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Fluoroscopy should not be
attempted by a veterinary surgeon unless his equipment fulfils the following
requirements:
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a. The screen must be covered by
a sheet of lead-glass with a lead equivalent of not less than 2 mm if used at
less 100 k .V.
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b. The X-ray tube and screen
should be on a common mounting and aligned on a common axis. Hand-held screens
must not be used.
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c.
The primary beam should be restricted by an adjustable lead-shuttered diaphragm
of the rectangular type.
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Further, to prevent lateral escape of radiation, the diaphragm system should be
mounted in a protective enclosure. The useful beam should not overlap the full
screen area.
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d. The fluoroscopic stand
must be provided with adequate protective arrangements of lead-rubber or lead-plywood of a lead equivalent not less than 0.5 mm to protect the operators and
handlers against scattered radiation.
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e. Protective clothing (aprons
and gloves) must also be worn by all persons participating in the examination.
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f. Each examination should be of
the shortest duration, using the lowest tube current .
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In medical radiography all
these requirements are met by using the correct equipment. There is also the
advantage of rarely having to restrain the patient during an examination.
