We've occasionally taken ad-hoc steps to harmonize with DICOM; for example, the use of DICOMweb's websockets influenced FHIRcast's, but there hasn't been a comprehensive harmonization.  I'd like to defer this comment until the project and working group seriously tackles the question of how to exchange image measurement data via FHIRcast. For example, a simple approach to DICOM/FHIRcast harmonization could simply be: use OAuth for DICOMWeb and publish the DICOMWeb url in the FHIR server's conformance statement.