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Cross-Community Access for Imaging (XCA-I)

The Cross-Community Access for Imaging (XCA-I) IHE profile makes it possible for communities to share imaging. Once a community uses an XCA actor to retrieve an Imaging Manifest with a ITI-38 Cross Gateway Query, it can use the XCA-I profile to retrieve the image referenced by that Manifest from a XDS-I.b Imaging Document Source. The community requesting access to an image uses an Initiating Imaging Gateway actor to send the XCA-I request to the Responding Imaging Gateway actor of the community that includes the Imaging Document Source. Specifically, the Initiating Imaging Gateway uses the Cross Gateway Retrieve Imaging Document Set transaction (RAD-75) to request the image from the Responding Imaging Gateway.

InterSystems products provide built-in components to create both XCA-I actors (Initiating Imaging Gateway and Responding Imaging Gateway) and to register an existing Imaging Document Source so these XCA-I actors can find it. At this time, InterSystems products do not provide pre-built components for creating an XDS-I.b Imaging Document Source actor.

Initiating Imaging Gateway

When a community’s Imaging Document Consumer actor needs to retrieve imaging from an XDS-I.b source, it sends a request to its local XCA-I Initiating Imaging Gateway actor using a Retrieve Imaging Document Set transaction (RAD-69). If the XDS-I.b source is located in a different community, the Initiating Imaging Gateway sends an XCA-I request message (RAD-75) to the Responding Imaging Gateway of the community that contains the imaging. If the XDS-I.b source is located in the same community as the Initiating Imaging Gateway, it retrieves the imaging directly without using a Responding Imaging Gateway.

Setting up the Initiating Imaging Gateway consists of creating an interoperability production that contains the following business hosts:

  • HS.IHE.XCAI.InitiatingGateway.Services

  • HS.IHE.XCAI.InitiatingGateway.Process

  • HS.IHE.XCAI.InitiatingGateway.Operations

In addition, you need to define an Service Registry entry for the Responding Imaging Gateway of every external community that contains an XDS-I.b source with imaging that the Initiating Imaging Gateway might need. This Service Registry entry includes the OID of the responding community. For each responding community with an XDS-I.b source:

  1. Open the Management Portal.

  2. Navigate to Health > IHE Configuration > OID Registry > Add/Edit OIDs, and select Add OID to add the OID of the responding community. When defining the fields of the OID, be sure that you select HomeCommunity in the Type field.

  3. Navigate to Health > Service Registry to create a new Service Name for the Responding Imaging Gateway. When defining the required fields of the Service Registry entry, be sure to:

    • Select the correct Code of the responding community in the HomeCommunity drop-down list. This is the Code for the community’s OID that you defined in the previous step.

    • Specify XCAI.Retrieve in the Device Function field.

When the Initiating Imaging Gateway receives a message from a Imaging Document Consumer actor, it examines the HomeCommunityId and uses the following logic to find the correct XDS-I.b source:

  • If the value of HomeCommunityId matches the home community of the Initiating Imaging Gateway, the local XDS-I.b source is identified by searching the Service Registry for the endpoint with Device Function = XDSI.Retrieve and a Repository that matches the message’s RepositoryUniqueId OID.

  • If the value of HomeCommunityId is not the same as the Initiating Imaging Gateway’s community, then the Responding Imaging Gateway where the XCA-I message will be sent is identified by searching the Service Registry for an endpoint with Device Function = XCAI.Retrieve and a HomeCommunity that matches the HomeCommunityId OID.

Responding Imaging Gateway

Using an InterSystems product to configure a responding community to accept XCA-I requests and return imaging from an XDS-I.b source consists of creating an interoperability production for the Responding Imaging Gateway and defining an OID and Service Registry entry for the XDS-I.b source.

The interoperability production for the Responding Imaging Gateway must include the following business hosts:

  • HS.IHE.XCAI.RespondingGateway.Services

  • HS.IHE.XCAI.RespondingGateway.Process

  • HS.IHE.XCAI.RespondingGateway.Operations

For details on defining the OID and Service Registry entry for the responding community’s XDS-I.b source, see Registering XDS-I.b Sources.

Registering XDS-I.b Sources

Though InterSystems products do not provide built-in components designed to create an XDS-I.b source, they do provide the ability to register existing sources from which images can be retrieved by XCA-I actors. The XDS-I.b source can be in the same community as the Initiating Imaging Gateway or it can be part of the Responding Imaging Gateway’s community, in which case the Responding Imaging Gateway will retrieve the image from the source when it receives an XCA-I request from another community.

Registering an XDS-I.b Imaging Document Source consists of defining an OID and Service Name entry as described in the following procedure:

  1. Open the Management Portal.

  2. Navigate to Health > IHE Configuration > OID Registry > Add/Edit OIDs, and select Add OID to add the OID of the Imaging Document Source. When defining the fields of the OID, be sure that you select Repository in the Type field.

  3. Navigate to Health > Service Registry to create a new Service Name for the XDS-I.b source. When defining the required fields of the Service Registry entry, be sure to:

    • Select the correct Code of the XDS-I.b source in the Repository drop-down list. This is the Code for the XDS-I.b source that you created in the previous step.

    • Select XDSI.Retrieve from the Device Function drop-down list.