The approach to the assessment of thoracic radiographs is summarised in Table 2.2

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:

  1. 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 looking for.
  2. Over-reading the radiograph, or jumping to conclusions (rather than describing the radiographic abnormality).
  3. When examining a film, note the position, normality or abnormality for each structure.
  4. 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.
  5. 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 subtle.
  6. 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.
  7. An over-inflated film is characterised by a flattened diaphragm and loss of contrast in the lung field.
Back to top
Back to menu