Key Takeaways:

• DICOM has defined new standardized services to obtain a complete inventory of a PACS/VNA
• These services are crucial to PACS migration, and useful for other operational and research functions
• PACS/VNA vendors will implement these services only if their customers demand them – if you manage a PACS, call your vendor

What would you do with a complete inventory of the contents of your PACS and/or VNA? Would you import it into your data warehouse to make you research data set more comprehensive? Would you analyze it for studies that are missing critical metadata, indicating operational problems in the radiology department? Would you sequester it offline as a backup in the event of a malware attack? Or would you use it as your PACS nears its end-of-life, to reduce the pain of migration to a new system (on-premises or cloud-based)?

In fact, your PACS will eventually reach its end-of-life, probably within the next 10 years (if not sooner). Having a complete inventory is critical to planning and executing a migration project. However, obtaining such an inventory has typically meant digging into the bowels of the PACS database, often undocumented and/or wrapped up in proprietary designs and data structures. It is therefore one of the major challenges for a smoother migration process.

This summer, work was completed on DICOM Supplement 223: Repository Query, Inventory IOD, and Related Services (https://www.dicomstandard.org/News-dir/ftsup/docs/sups/sup223.pdf). Sup223 adds a new set of features and services to the DICOM Standard to create and manage a complete inventory of the PACS archive that is application independent. “Application independent” means the data is in a DICOM Standard format and is not tied to the proprietary PACS database – it could be read by any DICOM-conformant application supporting this new feature.

Sup223 specifies several approaches that a PACS might use to produce an inventory. First, a PACS may produce a set of objects/files in accordance with the new Inventory Information Object Definition. Production of those files might be initiated by a local user control (the PACS UI), or through an optional DICOM remote service call. A second approach uses an enhanced version of DICOM Study Root Query to allow a robust traversal of the entire PACS database across a series of (many) Query transactions. This second approach fits easily into the architectural and commercial models of many existing PACS, and may facilitate implementation.

However, the next step is actually getting implementation of inventory services in PACS. DICOM is a voluntary standard, and there are no regulatory mandates regarding which of its defined features and capabilities are implemented in a PACS product. The only mandate is customer demand. So, if you are a PACS administrator, or a biomedical imaging researcher, or an enterprise IT director, and you see the utility of a DICOM Standard PACS inventory, it is up to you to tell your PACS vendor that you want them to implement these new features, and for you to start planning how to utilize the new capabilities. You may also want to consult with solution providers in the PACS migration or archive data management fields for ways to effectively use the new DICOM Inventory services.

Further information:

• Sup223 is incorporated into the published 2022c edition of the DICOM Standard, at https://www.dicomstandard.org/current. A suggested starting point is the informative Annex YYYY in Part 17 https://dicom.nema.org/medical/dicom/current/output/chtml/part17/chapter_YYYY.html.
• An extensive presentation on the details of Sup223 is online https://www.dicomstandard.org/news-dir/progress/docs/sups/sup223-slides.pdf.

Author Harry Solomon is an interoperability consultant for Laitek Inc., past Co-Chair of the DICOM Standards Committee, and principal author of Sup223. He has been involved in the development of DICOM since 1993, and has taught graduate courses in healthcare interoperability and standards at Northwestern University and at Oregon Health & Science University. Contact him at hsolomon@laitek.com.