Fig. 3

Conventional (a) and dark-field chest x-ray (b) of a healthy subject and a patient (#5) with alpha1-antitrypsin deficiency (AATD) (e, f). For both subjects, same window/level settings were applied within conventional and dark-field images, respectively. The dark-field signal is notably reduced in the lungs of the AATD patient (f), in particular in lower zones, whereas healthy lungs show a strong homogenous signal over all zones. Corresponding coronal computed tomography (CT) image (g) reveals lung parenchymal destruction, highlighted by emphysema overlay (red colour) using a threshold of -950 Hounsfield units (h) compared to images of healthy patient (c, d). Conventional chest x-ray fails to visualise extent of parenchymal disease in the AATD patient (e), showing similar transmission in the healthy patient (a). Only secondary signs like flattening of diaphragm, increased volume of lungs or widened costophrenic angles point to emphysema (e). While the dark-field image exhibits a generally reduced dark-field signal over the entire lung region in contrast to the normal lung, CT only reveals defects in lower regions which correspond to the stronger manifestation of signal reduction in the dark-field radiograph