What are PACS and RIS in radiology?

PACS (Picture Archiving and Communication System) replaced film-based workflows with digital image storage, retrieval, and display via DICOM. It comprises acquisition gateways, archive servers, and diagnostic workstations. RIS (Radiology Information System) manages administrative workflow: order entry, scheduling, patient tracking, structured reporting, and radiation dose tracking. Integration between PACS, RIS, and the EHR uses HL7 messaging and DICOM worklists.