Celebrate the amazing links between polar and Irish brown bears on International Polar Bear Day. Today, February 27, is International Polar Bear Day, an annual event to raise awareness about the conservation status of the polar bear and the impact global warming has had on polar bear populations.
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CT gantry with grating interferometer for dark-field imaging of a phantom human chest.
### Human-scale dark-field computed tomography
To produce 3D images of animal tissues, X-ray computed tomography (CT) infers contrast solely from differences in how X-rays are attenuated as they pass through tissues. Some wave aspects of X-rays, such as refraction and small-angle scattering, also contain useful diagnostic information, but technical challenges have impeded these properties from being exploited for human-scale imaging. Manuel Viermetz, Nikolai Gustschin, et al. describe a human-sized prototype that integrates a Talbot-Lau interferometer into a clinical CT gantry to glean previously unresolvable tissue microstructure from small-angle X-ray scattering, an approach termed dark-field CT. To address the sensitivity requirements for medical applications, the authors fabricated optical gratings fine-tuned with a custom analysis technique ensuring that the gratings are of sufficient qualit