The Diagnostic Imaging (DI) domain is used to maintain and manage information about orders and results for diagnostic imaging tests which constitute a vital part of a client Electronic Health Record. The technical requirements associated with the management and efficient communication of large images and other types of binary files is what sets this apart from the other domain services. This service allows for the centralised capture and sharing of DICOM compatible objects across a large distributed network. These networks include Picture Archiving and Communication Systems (PACS) implemented in hospitals or diagnostic centers as well as diagnostic modalities used to produce such pictures. Typically, there are two key pieces of data associated with a diagnostic imaging test, a written report outlining the conclusions of a study and the imaging artefacts which may take different forms such as video or sound but most often will take the form of one or several pictures. Both the written reports as well as the key picture(s) used to reach the conclusions expressed in such report are expected to be available from the DI service. The diagnostic images discussed herein are typically the end result of a business process that starts with an order created by a clinician for a certain type of test. The DI domain service is not expected to be used as an active computerized physician order entry (CPOE) system to manage or automate the workflow associated with the process of ordering DI tests. However, the order itself is expected to be represented within the DI domain service as a set of data in support of a given diagnostic image result and therefore is expected to be available as part of the electronic health record of clients.

Other types of large binary objects could also be handled by the DI domain capabilities, examples of those include clips of video streams coming from a telehealth session seen as clinically-relevant for a person’s health record, or eventually any digital stream coming from different modalities (ECG, Respiratory Monitors, etc…).

Providing fast, easy and responsive access to large picture or other types of streaming objects presents a challenge. The EHRi DI Domain services support EHR user requests to retrieve patient clinical data from the DI domain repository system for display. The centralized jurisdictional EHR Index service, provided as part of the Longitudinal Record Services, performs a vital role in recording the location and types of DI information a patient has received. This indexing mechanism is core to the operation of the DI domain service whenever an end-user is trying to access an image (or any object) for viewing.

The following EHRi DI Domain service operations represent the patient centric queries initiated by an EHR user in the context of an EHRi system.

Operations
Name	Return Type
Get DICOM Object()
Get DI Order()
Get DI Report()
List DI Exams()
List DI Orders()

Relations
Name	Type	Begins	Ends
	generalization	DI Domain Repository Services	EHR Data and Services

Description: This service allows an EHR user / point of service system to view DI images, evidence documents, and all other DICOM objects.

XDS-I uses the following level of abstraction for images

• The Diagnostic Image repository (DI-r), will store a patient’s DI documents as a DICOM Object called a “manifest”. A “manifest” describes a set of DICOM images and other objects intended for sharing. (This is to avoid treating each image as a separate document and, thereby, registering every image in the EHR Index which would be performance problem for the EHR Index as well as make it difficult for consumer applications to access a full exam)
• In XDS-I, the registry provides the OID and location pointer to the “manifest”. The consumer retrieves the manifest and parses it. When it does this, it gets a set of pointers to where the images are stored and initiates a DICOM C-MOVE (retrieve transaction)
• This “Get DICOM Object” operation retrieves the “manifest” from the DI-r via standard XDS transactions and allows a consumer to “view” the DICOM objects. It does not need the DICOM standard to complete this operation.
• Once the consumer has parsed the “manifest”, the consumer should use standard DICOM retrieve to get the images. This requires the consumer to initiate a DICOM transaction with the DI-r directly. This DICOM interaction is not described in this operation.

This service will allow the retrieval of the following types of DI documents:

• Full set of images (Exam)
• Set of pertinent images (Key Images)
• Evidence documents (requisition, technologist impressions, screening forms, etc)
• Other DICOM objects

The assumption is that the DI Domain Repository Service “List DI Exams” has been invoked first to locate the desired DICOM object.

Used By: IIP Get, Query EHRi Data

Uses: DI Domain Document query

Inputs:

• EHR Client ID
• EHR Index pointer to the location and method of access to the instance of the patient’s DI documents

Response: DICOM Object document

Rationale: This service allows an EHR user / system to retrieve a DICOM object from a DI domain repository.

This service operation will allow EHR users / PoS systems to view a DI order already placed in a DI Domain repository.

The assumption is that the DI Domain Repository Service “List DI Orders” has been invoked first to locate the desired DI Order via the EHR Index.

Used By: IIP Get, Query EHRi Data

Uses: DI Domain Order query

Inputs:

• EHR Client ID
• EHR Index pointer to the location and method of access to the instance of the patient’s DI Order in a DI domain repository

Response: DI Order Details

Rationale: This service allows an EHR user / system to retrieve details of a DI Order from a DI domain repository.

Description: This service allows an EHR user / point of service system to view a DI report (final, addendum, first impression) either in plain text or PDF format.

The assumption is that the DI Domain Repository Service “List DI Exams” has been invoked first to locate the desired DI Report for a DI Exam via the EHR Index.

Used By: IIP Get, Query EHRi Data

Uses: DI Domain Order query

Inputs:

• EHR Client ID
• EHR Index pointer to the location and method of access to the instance of the patient’s DI Report in a DI domain repository

Response: DI Report document

Rationale: This service allows an EHR user / system to retrieve a DI Report from a DI domain repository.

Description: This service allows an EHR user / point of service system to query and retrieve a list of a patient’s DI Exams using search criteria such as:

• EHR Client ID
• Document type – images, diagnosis, progress report, preliminary report, etc.
• Date Range
• Service Location
• Ordering Physician

Relevant metadata for this query includes (but is not limited to):

• Exam date
• Modality
• Body part/anatomical region
• Procedure code

Used By: IIP List, Query EHRi Data

Uses: This service searches the EHR Index for references to the patient’s DI Exams

Inputs:

• EHR Client ID
• Document type – images, diagnosis, progress report, preliminary report, etc.
• Date Range
• Modality
• Body part/anatomical region
• Procedure code
• Service Location
• Ordering Physician

Response:

• List of Patient’s DI Exams
  • DI Exam summary information
  • EHR Event ID (Instance ID of an Event)
  • Pointer to location of DI Exam

Rationale: This service will allow EHR users / systems to search the EHR for a patient’s DI Exams using different search criteria.

Description: This service allows an EHR user / point of service system to query and retrieve a list of a patient’s DI orders using search criteria such as:

• Type of DI Orders
• Modality
• Date Range
• Service Location
• Ordering Physician

Used By: IIP List, Query EHRi Data

Uses: This service searches the EHR Index for references to the patient’s DI Orders

Inputs:

• EHR Client ID
• DI Order Search Parameters (type of DI information to be found)
  • Type of DI Orders
  • Modality
  • Date Range
  • Service Location
  • Ordering Physician

Response:

• List of Patient’s DI Orders
  • DI Order summary information
  • EHR Event ID (Instance ID of an Event)
  • Pointer to location of DI Order

Rationale: This service will allow EHR users / systems to search the EHR for a patient’s DI Orders using different search criteria.