[PeterisP]

You don't need labels for the image if you can get them from other patient information, in particular, the diagnosis.

E.g. you know from image metadata that it's a chest x-ray of patient #1234 at 2012/03/04. Then you automatically check patient EHR near that date - do they have lung cancer Y/N; do they have broken ribs Y/N; do they have TB Y/N, etc, and make your image labels based on that. How diagnosis are codified, though, differs significantly between various medical systems, I have no idea how it's in USA EHR.