The one I worked for also included a viewer on discs burned for distribution (typic'ly to patients, but could go elsewhere if patient signed the right document), but we used a couple different viewers internally. If we received a disc, that DICOM data was imported using our viewers, never whatever was provided on the disc. Local network traffic was…closely monitored.
Occasionally, a remote doctor (not from our office) would call for help with the viewer we provided on disc. Usually, because some advanced feature they could have used at their office didn't exist in the patient viewer, or worked differently.
Normally, instead of discs, we just transceived images via PACS, or accepted physical films to be scanned into our PACS.