The Instance Availability Notification Service Class defines an application-level class-of-service that allows one DICOM AE to notify another DICOM AE of the presence and availability of SOP instances that may be retrieved. The AE from which such SOP Instances can later be retrieved may or may not be the SCU performing the notification.
Note: An example of usage of this Service Class is for the receiver of the instances to provide notification of their arrival and availability for subsequent workflow steps to a different entity, such as a separate workflow manager.
The SCU implementation defines the conditions under which it provides the notification. Certain SCUs may provide notification for arbitrary sets of SOP Instances, while other SCUs may provide notification when they determine that the instances associated with a Procedure Step or a Requested Procedure are available. The SCU is required to document in its Conformance Statement the nature of its notification decisions (e.g., frequency of notifications, retrieve capabilities and latency, etc.).
Once the SCU has provided notification about availability of the SOP Instances, the SCP may use that information in directing further workflow, such as in populating the Input Information Sequence and Relevant Information Sequence when forming General Purpose Scheduled Procedure Step. These types of policies are outside the scope of this Standard, however, the SCP is required to document these policies in its Conformance Statement.
The SCU of this Service Class is not required to assure that the study, procedure step or any workflow-related entity is “complete”; indeed no semantics other than the concept of “availability” is expressed or implied by the use of this service.
Notes: 1. The Performed Workitem Code Sequence (0040,4019) attribute of a referenced GP-PPS instance may provide the specific description of the work item that triggered the Instance Availability Notification.
2. The Instance Availability Notification is typically a service of the composite instance Storage SCP, since that application is responsible for making the instances available. The Instance Availability Notification allows that application to report the specific Retrieve AE Title, which may differ from the Storage Service AE Title, and which may vary with different instance SOP Classes, or may vary over time.
The Instance Availability Notification Service Class consists of a single SOP Class: the Instance Availability Notification SOP Class.
The SOP Class specifies Attributes, operations, and behavior applicable to the SOP Class. The conformance requirements shall be specified in terms of the Service Class Provider (SCP) and the Service Class User (SCU).
The Instance Availability Notification Service Class uses the Instance Availability Notification IOD as defined in PS 3.3 and the N-CREATE DIMSE Service specified in PS 3.7.
The DIMSE Services shown in Table R.3.1-1 are applicable to the Instance Availability Notification IOD under the Instance Availability Notification SOP Class.
DIMSE SERVICE GROUP
|DIMSE Service Element||Usage SCU/SCP|
The DIMSE Services and Protocols are specified in PS 3.7.
Note: Though the terminology “notification” is used for this Service Class, the notification is in fact performed through Operations rather than Notifications.
The Application Entity that claims conformance to this SOP Class as an SCU shall be permitted to invoke the following operations and the Application Entity that claims conformance as an SCP shall be capable of providing the following operations.
This operation allows an SCU to create an instance of the Instance Availability Notification SOP Class and to provide availability information about Instances that are under the control of the SCU. This operation shall be invoked through the DIMSE N-CREATE Service.
The Attribute list of the N-CREATE is defined as shown in Table R.3.2-1.
Table R.3.2-1 INSTANCE AVAILABILITY NOTIFICATION SOP CLASS N-CREATE ATTRIBUTES
|Attribute Name||Tag||Req. Type N-CREATE (SCU/SCP)|
|Specific Character Set||(0008,0005)||1C/1C (Required if an extended or replacement character set is used)|
|All other Attributes of SOP Common Module||3/3|
|Referenced Performed Procedure Step Sequence||(0008,1111)||2/2|
|>Referenced SOP Class UID||(0008,1150)||1/1|
|>Referenced SOP Instance UID||(0008,1155)||1/1|
|>Performed Workitem Code Sequence||(0040,4019)||2/2|
|>>Coding Scheme Designator||(0008,0102)||1/1|
|>>All other Attributes from Performed Workitem Code Sequence||3/3|
|Study Instance UID||(0020,000D)||1/1|
|Referenced Series Sequence||(0008,1115)||1/1|
|>Series Instance UID||(0020,000E)||1/1|
|>Referenced SOP Sequence||(0008,1199)||1/1|
|>>Referenced SOP Class UID||(0008,1150)||1/1|
|>>Reference SOP Instance UID||(0008,1155)||1/1|
|>>Retrieve AE Title||(0008,0054)||1/1|
|>>Retrieve Location UID||(0040,E011)||3/3|
|>>Storage Media File-Set ID||(0088,0130)||3/3|
|>>Storage Media File-Set UID||(0088,0140)||3/3|
The SCU shall specify in the N-CREATE request primitive the SOP Class and SOP Instance UIDs of the Instance Availability Notification SOP Instance which is created and for which Attribute Values are to be provided.
The SCU shall provide Attribute values for the Instance Availability Notification SOP Class Attributes as specified in Table R.3.2-1.
The use of additional optional Attributes by the SCU is forbidden.
Note: The reason for forbidding optional attributes is to prevent the use of Standard Extended SOP Classes that might add contextual information such as patient and procedure identifiers.
The encoding rules for Instance Availability Notification Attributes are specified in the N-CREATE request primitive specification in PS 3.7.
There are no requirements on when N-CREATE requests are required to be performed.
In particular, there are no requirements that notification about the availability of the first instance of a Performed Procedure Step or Study be provided upon its reception, nor that availability notification be provided when an entire set of instances comprising a completed Performed Procedure Step or Study are available, though these are typical and common scenarios.
The SCP shall return, via the N-CREATE response primitive, the N-CREATE Response Status Code applicable to the associated request.
There are no specific status codes. See PS 3.7 for response status codes.
The Instance Availability Notification SOP Class shall be uniquely identified by the Instance Availability Notification SOP Class UID, which shall have the value "1.2.840.10008.5.1.4.33".
Implementations shall include within their Conformance Statement information as described below.
An implementation may conform to this SOP Class as an SCU or as an SCP. The Conformance Statement shall be in the format defined in Annex A of PS 3.2.
An implementation that is conformant to this SOP Class as an SCU shall meet conformance requirements for the operations that it invokes.
Any Attributes for which Attribute Values may be provided (using the N-CREATE) by the SCU shall be enumerated in the SCU Conformance Statement. The SCU Conformance Statement shall be formatted as defined in Annex A of PS 3.2.
An implementation that conforms to this SOP Class as an SCU shall specify under which conditions during the performance of real-world activities it will create the SOP Class Instance.
The SCU Conformance Statement shall specify what is meant by each reported value of Instance Availability (0008,0056).
The SCU Conformance Statement shall describe the relationship between the Instance Availability Notification and the Performed Procedure Step SOP Classes, if the latter are supported.
An implementation that is conformant to this SOP Class as an SCP shall meet conformance requirements for the operations that it performs.
The SCP Conformance Statement shall be formatted as defined in Annex A of PS 3.2.
The SCP Conformance Statement shall provide information on the behavior of the SCP (in terms of real world activities) for each reported value of Instance Availability (0008,0056).
The SCP Conformance Statement shall describe the behavioral relationship between the Instance Availability Notification and the Performed Procedure Step SOP Classes, if the latter are supported.