Overnight in a 180-bed hospital the PACS viewer freezes while the CT scanner still acquires images, the RIS worklist is blank and the ED needs stroke head CTs read remotely by teleradiology with correct patient linkage. Which downtime action should the radiographer prioritize to preserve HIS, RIS and PACS linkage using DICOM and security rules?

The correct action preserves end-to-end identity across HIS, RIS and PACS during combined RIS and viewer failure by creating an auditable paper bridge with numbered downtime forms and captured accession data for later DICOM reconciliation, allowing the CT to keep acquiring, the ED stroke workflow to continue, and teleradiology to receive linkable studies under encryption and access controls. The modality-worklist-plus-secure-forward approach fails by provenance concept because locally entered modality entries without centrally issued downtime accession numbers create DICOM objects that are secure and timely but cannot be deterministically matched to the later-restored RIS orders and HIS encounter, risking duplicates and orphan images. The reboot-the-interface-engine approach fails by continuity concept because restarting integration services is a valid recovery task but does not provide immediate patient linkage and delays time-critical stroke interpretation while waiting for automatic repopulation. The HIS-emergency-registration approach fails by linkage concept because correct demographics in HIS alone do not generate RIS accessions or populate DICOM headers and worklists needed for PACS routing and remote reading. Exam caveat: when stems emphasize linkage using DICOM and security rules plus emergency remote reading, prioritize identity integrity and reconciliation over speed of transmission or system restoration alone. Practical check: verify downtime number on the form matches the DICOM Study ID and accession field, confirm encrypted transmission logs, and schedule RIS-PACS merge and verification before archiving.