Fig. 3

Optimising X-ray contrast. a A comparison of conventional attenuation (absorption) contrast and phase contrast radiographs of a rat, reproduced with permission from [27]. b CT section of an alligator head before and after 2 weeks of iodine staining, reproduced with permission from [28]. In a the conventional radiograph reveals the bone structure but not the soft tissue, whereas under grating-based phase contrast the soft tissues, including trachea and lungs, are well defined, the bones less so; in b only the bones are clear in the unstained sample, whereas staining reveals the soft tissues