Figure 7.

Effect of increasing the sample-to-detector distance from 2 cm to 50 cm when imaging the respiratory system of a mouse. The magnified region clearly shows the enhanced contrast at the edges of the lung. Inside the lung, a speckle pattern is seen which arises from the scattering from the small air sacs in the lung (alveoli). These chest images show that the intensity projection image (edge-enhanced image), recorded at a certain sample-to-detector distance, contains a mixture of contributions from both the absorption (e.g. the contrast of the bones) and the phase shifts (e.g. the contrast of the lung tissue) in the sample. This means that, in general, the edge-enhanced images only deliver qualitative data. Detector: Hamamatsu, 6.5 µm pixel size, 0.5 s exposure time. Scale bars: 2 mm, magnified area: 0.5 mm. 25 keV X-rays, flux 1.7 × 10¹⁰ photons s⁻¹. Flat-field and dark-current corrected. Linear grey-scale.