F.7.2.2 SET Modality Performed Procedure Step Information

This operation allows an SCU to set Attribute Values of an instance of the Modality Performed Procedure Step SOP Class and provide information about a specific real-world Modality Performed Procedure Step that is under control of the SCU. This operation shall be invoked through the DIMSE N-SET Service.

F.7.2.2.1 Modality Performed Procedure Step IOD Subset Specification

The Application Entity which claims conformance to this SOP Class as an SCU may choose to modify a subset of the Attributes maintained by the SCP. The Application Entity which claims conformance as an SCP to this SOP Class shall support the subset of the Modality Performed Procedure Step Attributes specified in Table F.7.2-1.

The character set used for Attribute Values updated using the N-SET shall be the same as that specified by the N-CREATE Request Primitive.

F.7.2.2.2 Service Class User

The SCU shall specify in the N-SET request primitive the UID of the Modality Performed Procedure Step SOP Instance for which it wants to set Attribute Values.

The SCU shall be permitted to set Attribute values for any Modality Performed Procedure Step SOP Class Attribute specified in Table F.7.2-1. The SCU shall specify the list of Modality Performed Procedure Step SOP Class Attributes for which it wants to set the Attribute Values. The SCU shall provide, with one or more N-SET request primitives, the attribute values specified in Table F.7.2-1. The encoding rules for Modality Performed Procedure Step Attributes are specified in the N-SET request primitive specification in PS 3.7. The SCU shall only set Attribute Values which are already created with an N-CREATE request.

The SCU shall not send N-SET request primitives for a Modality Performed Procedure Step SOP Instance after a N-SET request primitive with a value for the attribute “Performed Procedure Step Status” (0040,0252) is “COMPLETED” or “DISCONTINUED” has been sent.

If Sequences are included in a N-SET command, all Items of a Sequence are to be included in the command and not only the Items to be updated.

Once the Modality Performed Procedure Step Status (0040,0252) has been set to “COMPLETED” or “DISCONTINUED” the SCU shall no longer modify the Modality Performed Procedure Step SOP Instance, and shall not create new Composite SOP Instances as part of the same Modality Performed Procedure Step SOP Instance.

Note: A Modality that wishes to continue or resume creating Composite SOP Instances may create a new Modality Performed Procedure Step.

Before or when Modality Performed Procedure Step Status (0040,0252) is set to “COMPLETED” or “DISCONTINUED” the SCU shall have created or set all the Attributes according to the requirements in the Final State column of Table F.7.2-1.

Before or when Modality Performed Procedure Step Status (0040,0252) is set to “COMPLETED” or “DISCONTINUED” the SCU shall have sent to the SCP a list of all Image SOP Instances and all Non-Image Composite SOP Instances created during the Procedure Step in Referenced Image Sequence (0008,1140) and Referenced Non-Image Composite SOP Instance Sequence (0040,0220) respectively.

Notes: 1. The intent is that a completed or discontinued Modality Performed Procedure Step entity will contain a complete list of all the Images and Non-Image Composite SOP Instances that were created.

2. The distinction between the list of images and non-images is present for historic reasons only, and has no semantic significance.

The Modality Performed Procedure Step Status (0040,0252) shall not be set to “COMPLETED” or “DISCONTINUED” if the list contains neither Image references nor Non-Image Composite SOP Instance references, unless no such Instances were created.

F.7.2.2.3 Service Class Provider

The N-SET operation allows the SCU to request that the SCP update selected Attribute values for a specific Modality Performed Procedure Step SOP Instance. This operation shall be invoked through the use of the DIMSE N-SET Service used in conjunction with the appropriate Modality Performed Procedure Step SOP Instance.

The SCP shall return, via the N-SET response primitive, the N-SET Response Status Code applicable to the associated request. Contingent on the N-SET Response Status, the SCP shall update the Referenced Performed Procedure Step Attributes.

The SCP shall accept N-SET request primitives only if the value of the already existing attribute “Performed Procedure Step Status” (0040,0252) is “IN PROGRESS”. If the already existing Performed Procedure Step Status attribute has another value, the SCP shall set the failure status code “Processing failure” (Code: 0110H) with a Specific Error Comment (see Section F.7.2.2.4).

The SCP may itself modify any Attributes of the Modality Performed Procedure Step SOP Instance only after the “Performed Procedure Step Status” (0040,0252) has been set to “COMPLETED” or “DISCONTINUED”.

Notes: 1. Such coercion of Attributes by the SCP may be necessary to correct, for example, patient identification information or incorrectly selected scheduling information. Such an operation is not permitted to the SCU by the requirements described in Table F.7.2-1, which might create a new Modality Performed Procedure Step SOP Instance to achieve the same objective.

2. Under exceptional circumstances, it may be necessary for the SCP to itself set the Performed Procedure Step Status (0040,0252) to COMPLETED or DISCONTINUED, for example if the Modality has failed. When the Modality recovers, subsequent N-SETs may fail.

F.7.2.2.4 Status Codes

The specific error comment which may be returned as a status code in a N-SET-RSP is defined in Table F.7.2-2. See PS 3.7 for additional response status codes.

Table F.7.2-2

N-SET STATUS

Service Status Further Meaning Status Code Error Comment (0000,0902) Error ID (0000,0903)
Failure Processing Failure 0110H Performed Procedure Step Object may no longer be updated A710