Fig. 2

Phantom study for foreign-body detection with x-ray dark-field radiography. The test structures made of aluminium and wood were prepared onto a PMMA plate with 1.8 cm thickness for phantom configuration 1. The diameters of the structures were about 0.5, 0.7, 0.9, and 1.1 mm increasing from right to left. We aligned two splinters of each size perpendicularly to each other. In all images, the wooden test structures are on the top and the aluminium structures are on the bottom. The conventional attenuation is displayed on the upper row, the x-ray dark-field images on the lower row. a The radiographies at 5s exposure time per step. The same configuration has been imaged with 1s exposure time (b). c The phantom configuration 2 (i.e. with an additional aluminium plate) at 2s exposure time per step