However, it has also been reported that quantitative analyses of emphysema are sensitive to technical factors during CT scanning or reconstruction.5–10 Both differences in CT manufacturers or scanners and several imaging factors can affect the results, such as radiation dose settings, reconstruction kernels, or slice thickness. For example, it is well known that using sharp reconstruction kernels (for lung or bone) usually results in overestimating the extent of emphysema; therefore, standard kernels (for soft tissue) are recommended for CT-based quantitative analysis of emphysema.5,6 It is also known that different tube current settings result in inconsistent measurements, which result in overestimating the extent of emphysema when using lower tube current settings.7,8