December 27, 2010

ILO International Classification of Radiographs of Pneumoconioses (1)

PA chest radiograph of an 80-year-old man who was a miner decades ago shows multiple large opacities (arrows, large opacity = parenchymal opacity greater than 1 cm) and several tiny rounded opacities in the right lower and left mid/lower lung zones. With the history of exposure, adequate lag time and chest radiographic findings, the patient has findings consistent with coal worker pneumoconiosis.

Background: ILO
  • ILO (International Labour Office, based in Geneva) produces guidelines on how to classify chest radiographs of persons with pneumoconioses
  • The guidelines aim to standardize classification and facilitate comparisons of data internationally
  • The last ILO revision of this classification was in 2000, it is specific for postero-anterior (PA) chest radiography only
  • Because interpreting chest radiography for pneumoconiosis has shown an unacceptable variability, the US's National Institute for Occupational Safety and Health (NIOSH) began the "B" reader program in 1978. The "B" reader has to pass the certification examination organized by NIOSH.
  • It is important to note that there is no pathognomonic imaging sign of pneumoconioses*. Diagnosis requires a combination (2 out of 3) of history of exposure, radiographic findings and pathological findings.
  • Based on ILO classification, these informations on PA chest radiographs are required for reporting: technical quality of the film, parenchymal abnormalities, pleural abnormalities, symbols (findings other than that of pneumoconiosis) and comments.
  • Parenchymal opacities are divided into small and large opacities. Small opacities can be rounded or irregular. These are further subdivided based on their size
  • Pleural abnormalities can be focal plaque, costophrenic angle obliteration and diffuse pleural thickening
1. ILO. Guidelines for the use of the ILO international classification of radiographs of pneumoconioses, revised edition 2000.
2. Wikipedia. "B" reader.

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