Radiology informatics is the discipline of managing imaging data and the systems that carry it: acquisition, storage, retrieval, reporting, exchange and analysis. In practice it covers the PACS, the RIS, the standards they speak, and increasingly the AI applied to both the images and the operation around them.

Informatics is a discipline, not a product. Nobody sells you "informatics".
In practice it means the systems and the standards: PACS, RIS, DICOM, HL7 and FHIR.
The operational half is underrated. Most informatics attention goes to images; most wasted time is in the workflow around them.