The idea that every piece of trivially copyable information should have an "owner" is the root problem here. No one needs to "own the copyright" to these images

The idea that every piece of trivially copyable information should have an "owner" is the root problem here. No one needs to "own the copyright" to these images at all. Copyright is for "creative works" and should not apply here at all. So the NHS can use them for their purposes like monitoring trends across patients, the manufacturer can use them for their purposes like testing their machine, and you can use them for your purposes - even post them to your social media if you're so inclined. Other rules like protecting patient confidentiality may apply to the NHS and the manufacturer, but copyright should not apply.