In reply to Cameron Neylon.

Maybe we have to agree to disagree here. I don't think I can get behind controlled access as a generalized solution for patient images because it puts another barrier in the way of scientific discovery, particularly where matching disease phenotypes will be critical and ultimately computational. Controlled access is (currently) a necessity for certain data, but I think anyone who's used dbGaP would be dismayed at the notion that something similar would be needed for photographs.

Finally I'd just add that all (except one) flavors of CC licenses provide some restriction/condition. Surely, if (re)use of an open corpus is the over-riding concern, then shouldn't we be agreeing that CC BY is inappropriate (my original query) and that CC0 should be mandated? If that is not the case then I don't see a dedicated hypothetical CC BY-related license created for medical images being that different from CC BY in terms of reuse.