How providers and staff can help patients to contribute
Give them DICOM CDs

Seriously, that's about all it takes.

They will also need copies of their radiology and pathology reports to scan and upload, and if you have the means to provide these electronically as well, either on the same CD as the images, or on some other medium, regardless of file format, that would be great too.

(Much) more detail will follow here shortly, including a one page "handout" sheet in PDF that the patients can take to their local doctors and imaging centers to encourage them to help.