A biomarker of lung condition can conventionally be obtained using a spirometer. A spirometer provides an estimate of the volume of air expelled by the lungs. This is a rather indirect biomarker of the staging of a lung condition, because a reduction in lung volume may only manifest itself at a point where symptoms are well advanced. A lung condition such as Chronic Obstructive Pulmonary Disorder (COPD) is typically not visible on conventional X-ray attenuation images, because the relevant tissue (alve-oli-bearing microstructured lung tissue) contains a lot of air. The X-ray dark- field can successfully indicate microstructure, such as lung alveoli. Therefore, imaging the lungs using the dark-field can provide information on the status of COPD.
