Objective:To explore the application value of the method of judging the density of small shadows in the lung area by using CT and CT reference films for pneumoconiosis.Methods:The chest imaging data of 244 employees of a large copper company in Tongling City, Anhui Province who underwent occupational physical examination at Tongling Municipal Hospital in Anhui Province from January 2016 to December 2019 were retrospectively analyzed. Totally 244 cases underwent chest CT scan and chest DR radiography at the same time. The shape and size of the small shadows (the size of the circular and quasi-circular nodules in the lung area were represented by p, q, r, and the size of the irregular small shadows were represented by s, t, u), the overall density, the density of small shadows in each lung area, the large shadows, and the diagnosis stage were observed and compared. The small shadow density of each lung area was judged by the method of judging the small shadow density of CT lung area and the reference film, and other observation indicators were judged according to GBZ70-2015 Diagnosis of Occupational Pneumoconiosis. Results:There was a significant difference between CT and DR in judging s-shaped small shadows and no small shadows ( P<0.05), and there was no statistically significant difference in judging p, q, r, t, and u-shaped small shadows ( P>0.05). CT and DR had medium to high consistency in the judgment of the overall density of small shadows (Kappa=0.692, P=0.001), and the diagnostic coincidence rate was 82.38% (201/244). There was moderate to high agreement between CT and DR in the density of small shadows shown in the right upper, right lower, left upper, left middle, and left lower lung regions (Kappa ranged from 0.40 to 0.75, P<0.05), and the consistency in the right middle lung region was poor (Kappa=0.381, P=0.001). Eleven large shadows were detected in 8 cases by DR, 31 large shadows were detected in 23 cases by CT, and 20 (8.20%) large shadows were detected more frequently by CT than DR. The agreement between CT and DR for the diagnosis and staging of silicosis was excellent (Kappa=0.843, P=0.001), and the diagnostic coincidence rate was 91.80% (224/244). Conclusion:Applying the method of determining the density of small shadows in the lung area of pneumoconiosis and reference films, combined with GBZ70-2015 Diagnosis of Occupational Pneumoconiosis, can make a more accurate diagnosis of silicosis.