The approach to the assessment of thoracic radiographs is summarised in
The viewing box should be in good order
and should be used in a darkened room.
Masking off unexposed
parts of the film and unused parts of the viewer enhances film reading. A
bright (hot) light is often helpful to
view small areas of darker film.
Radiographs should be assessed in a quiet
environment without distractions.
X-rays should be viewed in a consistent
manner. Lateral radiographs are usually placed with the
animal's head to the left and a DV or VD
radiograph with the animal's right side to the viewer's
It is important to adopt a routine to ensure
the entire film is inspected thoroughly.
There are two common errors in film reading:
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Not looking at the whole film and overlooking
an abnormality (blinkered by what you want to see); some radiologists therefore
prefer to read a film cold, i.e. with no preconceived notion of what they are
Over-reading the radiograph, or jumping
to conclusions (rather than describing the radiographic
When examining a film, note the position,
normality or abnormality for each structure.
In normal animals the predominant pattern
in the lung is due to the pulmonary vessels while the
additional greyness of the pattern can
be attributed to the lung parenchyma.
Marginal over- or under-exposure can
result in marked changes in radiographic detail that can
significantly affect interpretation and
reduce diagnostic value, if the pathological changes are
A thoracic radiograph with poor lung
inflation is characterised by increased soft tissue density (i.e. lacking air
contrast), making structures indistinct and potentially leading to over-interpretation
of the density.
An over-inflated film is characterised
by a flattened diaphragm and loss of contrast in the lung field.
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