Abstract
In the studies of diagnosis of pneumoconiosis, 533 cases inhalating mineral dust in high and low concentrations were examined. The distribution of the nodular shadows due to pneumoconiosis was studied by comparing the International Standard of Radiological Classification of Pneumoconiosis, adopted in the third International Conference of Pneumoconiosis, with Oka's classification which we had previously used.
Even in the earliest stage the nodular shadows were seen in the outer one-third of the lung field in most of the cases. For this reason it is believed that further study is required befor the degree of pneumoconiosis can be determined chiefly by the distribution areas of the nodular shadows.
Furthermore, the size of the nodular shadows, in the cases of low concentration-inhalation was not proportional to the number of working years under mineral dust. The number of the shadws, but not the size, increased in a greater part of the cases, and the progress to the end of the “first degree” was comparatively rapid, few reaching the “second degree”. However, the rapidity of the development of the disease was observed to be influenced by individual differences. The pleural adhesions were mostly noticed in those with tuberculous findings. Bleb-formation of emphysema was seen in the comparatively early stages. The size of the destinction-shadows due to pneumoconiosis in the hilum lymph nodes were mostly two or three centimeters.
