Measurement of Pneumoconiosis by Computer

We describe and assess computer programs for measuring pneumoconiosis in chest X-rays. The 36 films studied had been read by 11 skilled human observers and a radiological score of pneumoconiotic severity was therefore available for each film. The computer assigns to each square grid of side 3.6 mm a measure which reflects the ``unevenness´´ of the density distribution in that grid. The computed score is defined as the mean diversity over all relevant grids in both lung fields. On the set of 36 films the correlation between radiological score and computed score was 0.88. By contrast the correlation between the score assigned by a single observer and the average of the scores assigned by the other 10 was in the range 0.95 to 0.99. The program can use the computed score to classify a film to one of the four major UICC categories, the success rate of this process being 80 percent as compared to those quoted by other workers in the range 45 percent-65 percent. If the films used in this study are typical then the program described may form the basis of an automatic method for measuring pneumoconiosis in epidemiological work.