Are Doctors Required to Obtain Patient Permission For Posting Non-Identifiable X-Rays, CT Scans, Etc Online?

The blunt answer is no... as long as there is no way the patient can be identified by looking at the image. (in other words, anonymous).

Dr. Ves Dimov at CasesBlog has written a very good article regarding this very question and the guidelines used to determine whether patient permission is required or not.

Read his blog article here.