Abstract
Computed tomographic study on 50 asbestos exposed workers who have some of the roentgenographic changes caused by asbestos exposure on the chest was made. After that study, 236 asbestos exposed workers of a certain Japanese National Railways (JNR) repair facility were taken chest roentgenograms of PA projection, right oblique projection and left oblique projection at an angle of 30°.
Computed tomographic examination of the chest of the asbestos exposed workers showed pleural plaques in all areas of the chest wall, but the distribution was unbalance. There were few plaques in costal cartilage area, and there were many plaques in paravertebral area.
On the other hand, there were no plaque in costal cartilage area, anterior area and lateral area of the chest wall in contorols. The types of plaques were Ia except for 3 cases suspected Ib.
Paravertebral area was very difficult to assess on routine chest radiographs and there were no cases of detection of pleural plaques.
Thirty cases (83%) out of 36 cases of pleural plaques in anterior area and posterior area of the chest wall were detected on the routine fronal view of the chest. In order to detect the plaques in anterior area and posterior area of the chest wall, the most suitable oblique angles which were calculated using computed tomography were between 20° and 45° in right and left oblique projection.
