Query/retrieve and archives

Routes can search and retrieve from archives (PACS, VNAs) on behalf of viewers, workstations and itself (for prior studies). Viewers see one archive, however many sit behind the router.

Archives

A DICOM destination becomes an archive by ticking Query/retrieve archive on it. Per archive:

• How it is retrieved from:
  • through the router (C-GET): the archive needs nothing set up, and what is retrieved for a destination goes through its queue;
  • by the archive (C-MOVE): it sends straight to the target’s AE title, so it must know every target.
• The most matches taken from it for one query (default 1000).
• Other sending addresses: where its C-STOREs may come from besides its own host, such as the other servers of a PACS cluster.

Who may search

A source’s senders may query and retrieve when the source allows it (May query and retrieve), from every archive or only some. A sender that no route accepts but whose source may query is accepted for query/retrieve only.

DICOM: C-FIND, C-MOVE, C-GET

Study Root and Patient Root.

• C-FIND goes to every archive at once, and the answers are merged, each match once. The router is named as the Retrieve AE Title.
• C-MOVE to the AE title of one of the router’s destinations is retrieved through the router and queued for that destination, with its edits, de-identification, retries and history. Archives that retrieve by C-MOVE are asked to send straight to the move destination instead.
• C-GET is retrieved through the router and sent back on the same association as the instances arrive.

DICOMweb: QIDO-RS and WADO-RS

Web viewers such as OHIF search and display studies through the router’s DICOMweb port: see DICOMweb.

Audited

Every search and retrieval through the router is in the audit log: who asked, by which protocol and from where, the node, the study, what was asked for and the outcome. These entries name patients, so only those who may see the history see them. A repeated identical search within a minute is recorded once.