What are multiple IMPAX cluster configurations?

Multiple IMPAX cluster configurations use cluster linking to connect more than one system at a site or multiple systems between sites. In Multiple IMPAX cluster configurations, users can query and retrieve studies from all the clusters as though they were one, regardless of the physical location of the system. Queried locations can include studies in cache, archived studies, and offline studies.

While the terms cluster linking and database linking are often used interchangeably, they are different. Database linking (or linked databases) is an attribute of database systems, while cluster linking is accomplished with standard and private DICOM messages that flow between each cluster. If the PACS system conforms to the linking specification, then data can be synchronized between the PACS systems. IMPAX uses cluster linking to integrate systems at or between sites.

Types of information communicated

Linked queries allow more information to be communicated between systems than a strictly DICOM query. This information includes:

Interpretation (report) status (New, Dictated, Transcribed, Approved, and so on)
Best study location (cache, non-cache)
Number of images in the study (also available via DICOM in some instances)
Specialty (as computed by remote system using mapping tables)
Body part (as computed by remote system using mapping tables)
Verified status of study

Advantages of multiple IMPAX cluster configurations

Extends the types of constraints used to find studies.
Allows the physician to query all clusters for a particular patient without keeping track of where a patient might have had a prior exam.
Allows physicians to retrieve and display studies from remote clusters, update the studies, and save them to the home cluster.
Provides status and markup/annotation information between clusters automatically.
Updates linked clusters when images or series are added to a study, so all clusters have the complete study.
Prefetches relevant priors from other clusters.

When database queries are performed, standard DICOM queries used in the IMPAX Client to query remote clusters are replaced by linked queries.

Limitations of cluster linking

Only unidirectional linking is available between IMPAX systems and third-party PACS systems. Fewer data columns and search criteria are available in the IMPAX Client, and study changes cannot be saved in either direction.
Cluster linking is restricted to information about database queries and study/image updates. It does not include the linking of any type of configuration information such as DICOM network configuration tables, routing tables, mapping tables, or user profiles. All this information must be maintained independently in each system.
Sharing caches between linked clusters is not supported.
Image deletions and additions (such as summary series creation) made in the Client Image area are not saved back to the home cluster.
Bidirectional cluster linking can link two or three IMPAX clusters together. Beyond three IMPAX clusters, all status and markup updates go to all clusters for all studies, regardless of whether the study is at the remote location or not. With each site added to the system, this update traffic increases on each Database Server.