OpenStax College (cnx.org) has a large number of image files/illustrations available for use under CC BY 3.0 creative commons. Many of these are excellent. In the spirit of Free Open Access Medical education, we undertook to transfer illustrations that would be useful to add to Radiopaedia and upload the images under a bespoke OpenStax College.
All the images were of course appropriately attributed (example case) and were then added to relevant articles (example article). In many instances, a square crop was performed to make the images work better in the Radiopaedia layout.
The team consisted primarily of Andrew Dixon (lead), Chamath Ariyasinghe (aka "Spangles"), Henry Knipe and Humberto Rodrigo Tibau, although many others pitched in.
Overall 30 'cases' were created, each containing numerous images. Check them all out here.
Best of all, these images can then be used to illustrate specific features in years to come.