Minor side note: I did that too but found that institutions were locked down and could not access my public server, and they wouldn’t accept a usb drive with the same data. They were only set up to receive FAT dvds - and I spent many, many hours duping DVD’s for doctors in their waiting rooms.
The USB thing might be a security policy in action. The DVD (and that's weird, because I think I've never seen DVDs, but lots of CDRs) is probably a historical thing related to the DICOM Supplement 19 General Purpose CD-R Image Interchange Profile standard.
