Quantifying lung and diaphragm morphology using radiographs in normative pediatric subjects, and predicting CT‐derived lung volume

Objective To quantify the effect of age on two‐dimensional (2D) radiographic lung and diaphragm morphology and determine if 2D radiographic lung measurements can be used to estimate computer tomography (CT)‐derived lung volume in normative pediatric subjects. Materials and Methods Digitally reconstructed radiographs (DRRs) were created using retrospective chest CT scans from 77 pediatric male and female subjects aged birth to 19 years. 2D lung and diaphragm measurements were made on the DRRs using custom MATLAB code, and Spearman correlations and exponential regression equations were used to relate 2D measurements with age. In addition, 3D lung volumes were segmented using CT scans, and power regression equations were fitted to predict each lung's CT‐derived volume from 2D lung measurements. The coefficient of determination (R2) and standard error of the estimate (SEE) were used to assess the precision of the predictive equations with p