The relationships between pulmonary function tests and the findings on chest X-P were statistically analyzed in 162 cases of silicosis. The respiratory function tests were spirography (VC, FEV1), measurements of the lung volumes (TLC, FRC, RV, RV%), CO2 diffusing capacity by single breath methods (DLCO, DLCO/VA), arterial blood gas analysis (PaO2, PaCO2, pH, AaDo2), and mechanical properties (Pel, Cst, Cdyn/Cst, RL, RL). The findings on chest X-ray film in silicosis are divided broadly into three categories: the types and profusion of small opacities and the size of large opacities. The authors observed the statistically significant correlation between the types and profusion (p<0.01), and between the profusion and the size of large opacities (p<0.05). Therefore, taking that correlation into account, the relationships between the function and the roentgenographic findings were investigated by means of multiple regression analysis: the parameters of the function were regarded as criterion variables and the three chest X-ray film categories as predictor variables. The results were as follows: 1) the disturbances of Pel, Cst, lung volumes (VC, TLC, FRC), parameters of obstructive impairment (FFV1, V50, V25, RL, RT, ) and DLCO were in parallel with the grade of profusion of small opacities and the size of large opacities. 2) The parameters correlating with the types of small opacities were merely RL and RT. 3) The relation between the parameters and those mentioned above (RV, %RV, V50/V25, Cdyn/Cst, DLCO/VA and the blood gas parameters) and the grade of chest X-ray film were not significant.
