Roentgenographic determination of total lung capacity: normal values from a National Population Survey.

Planimetric measurements of total lung capacity (TLC) were made from posteroanterior and lateral chest roentgenograms obtained during a nationwide survey of the civilian, noninstitutionalized United States population. Regression equations for TLC, residual volume (RV), and the ratio of RV to TLC for healthy, nonsmoking participants are presented. The equations predict values that agree closely with previously published normal values obtained by other methods.