The SCU shall specify in the N-CREATE request primitive the Class and Instance UIDs of the Modality Performed Procedure Step SOP Instance which is created and for which Attribute Values are to be provided.
Note: This requirement facilitates the inclusion of relevant Attributes in the Composite SOP Instances generated during the Performed Procedure Step.
The SCU shall provide Attribute values for the Modality Performed Procedure Step SOP Class Attributes as specified in Table F.7.2-1. Additionally, values may be provided for optional Modality Performed Procedure Step IOD Attributes that are supported by the SCP. The encoding rules for Modality Performed Procedure Step Attributes are specified in the N-CREATE request primitive specification in PS 3.7.
The SCU shall be capable of providing all required Attribute values to the SCP in the N-CREATE request primitive. The SCU may provide Attribute values for optional Attributes which are not maintained by the SCP. In such case the SCU shall function properly regardless of whether the SCP accepts values for those Attributes or not.
All Attributes shall be created before they can be set. Sequence Attributes shall be created before they can be filled. Sequence Item Attributes shall not be created at zero length.
Note: Not all the attributes that can be created can be set afterwards (see Table F.7.2-1).
The SCU shall only send the N-CREATE request primitive with the value for the Attribute “Performed Procedure Step Status” (0040,0252) set to “IN PROGRESS”.
Notea: 1. It is assumed but not required that the SCU (the modality) received the Study Instance UID within the scope of the Basic Worklist Management SOP Class.
2. If the SCU has grouped multiple Requested Procedures into a single performed step the Study Instance UID (0020,000D) attribute within the Scheduled Step Attributes Sequence (0040,0270) may be the Study Instance UID (0020,000D) for the study that contains all images and non-image composite instances created during performance of the current step. This value may be generated by the SCU and may be the same for all items of the sequence. In addition, the Referenced Study Sequence (0008,1110) may contain the Study Instance UIDs from the Requested Procedures being grouped.
3. If the SCU does not have available Scheduled Procedure Step data applicable to the current step, the SCU may generate a value for the Study Instance UID (0020,000D) attribute within the Scheduled Step Attributes Sequence (0040,0270). This value of the Study Instance UID (0020,000D) may be stored in all mages and non-image composite SOP instances created during performance of this step. All other attributes within the Scheduled Step Attribute Sequence (0040,0270) may be set to zero length for 2/2 requirement types or absent for 3/3 requirement types (see Table F.7.2-1) .