DICOM PS3.4 2021c - Service Class Specifications

C.5.2 Association Negotiation for C-MOVE SOP Classes (Current)
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### C.5.2 Association Negotiation for C-MOVE SOP Classes

The following negotiation rules apply to DICOM SOP Classes and Specialized DICOM SOP Classes of the Query/Retrieve Service Class that include the C-MOVE operation.

The Association-requester (retrieval SCU role) shall convey in the A-ASSOCIATE request:

- one Abstract Syntax, in a Presentation Context, for each retrieval based SOP Class supported

- optionally, one SOP Class Extended Negotiation Sub-Item, for each retrieval based SOP Class

The Association-acceptor (retrieval SCP role) of an A-ASSOCIATE request shall accept:

- one Abstract Syntax, in a Presentation Context, for each retrieval based SOP Class supported

- optionally, one SOP Class Extended Negotiation Sub-Item, for each retrieval based SOP Class

#### C.5.2.1 SOP Class Extended Negotiation

The SOP Class Extended Negotiation allows, at Association establishment, peer DICOM AEs to exchange application Association information defined by specific SOP Classes. This is achieved by defining the Service-class-application-information field. The Service-class-application-information field is used to define support for relational-retrievals.

This negotiation is optional. If absent, the default condition shall be:

- no relational-retrieval support

- no Enhanced Multi-Frame Image Conversion support

The Association-requester, for each SOP Class, may use one SOP Class Extended Negotiation Sub-Item. The SOP Class is identified by the corresponding Abstract Syntax Name (as defined by PS3.7) followed by the Service-class-application-information field. This field defines:

- relational-retrieval support by the Association-requester

- Enhanced Multi-Frame Image Conversion support by the Association-requester

The Association-acceptor shall return a single byte field (single sub-field) if offered a single byte field (single sub-field) by the Association-requester. The Association-acceptor may return either a single byte field (single sub-field) or a multiple byte field if offered a multiple byte field by the Association-requester. A one byte response to a multiple byte request means that the missing sub-fields shall be treated as 0 values.

### Note

The restriction to return only a single byte field if that was all that was offered is because the original DICOM Standard only contained one byte and older systems may not be expecting more.

The Association-acceptor, for each SOP Class Extended Negotiation Sub-Item offered, either accepts the Association-requester proposal by returning the same value (1) or turns down the proposal by returning the value (0).

If the SOP Class Extended Negotiation Sub-Item is not returned by the Association-acceptor then relational-retrievals and Enhanced Multi-Frame Image Conversion are not supported (default condition).

If the SOP Class Extended Negotiation Sub-Items do not exist in the A-ASSOCIATE indication they shall be omitted in the A-ASSOCIATE response.

##### C.5.2.1.1 SOP Class Extended Negotiation Sub-Item Structure (A-ASSOCIATE-RQ)

The SOP Class Extended Negotiation Sub-Item consists of a sequence of mandatory fields as defined by PS3.7. Table C.5-3 defines the Service-class-application-information field for DICOM Query/Retrieve SOP Classes and Specialized DICOM Query/Retrieve SOP Classes that include the C-MOVE and C-GET operations.

Table C.5-3. SOP Class Extended Negotiation Sub-Item (Service-Class-Application-Information Field) - A-ASSOCIATE-RQ

Item Bytes | Field Name | Description of Field
--- | --- | ---
1 | Relational-retrieval | This byte field defines relational-retrieval support by the Association-requester. It shall be encoded as an unsigned binary integer and shall use one of the following values 0 - relational-retrieval not supported 1 - relational-retrieval supported
2 | Enhanced Multi-Frame Image Conversion | This byte field defines whether or not the Attribute Query/Retrieve View (0008,0053) shall be used to adjust the view returned in queries to consider conversion to or from Enhanced Multi-Frame Images. It shall be encoded as an unsigned binary integer and shall use one of the following values 0 - Query/Retrieve View not supported 1 - Query/Retrieve View supported

##### C.5.2.1.2 SOP Class Extended Negotiation Sub-Item Structure (A-ASSOCIATE-AC)

The SOP Class Extended Negotiation Sub-Item consists of a sequence of mandatory fields as defined by PS3.7. Table C.5-4 defines the Service-class-application-information field for DICOM Query/Retrieve SOP Classes and Specialized DICOM Query/Retrieve SOP Classes that include the C-MOVE and C-GET operations.

Table C.5-4. SOP Class Extended Negotiation Sub-Item (Service-Class-Application-Information Field) - A-ASSOCIATE-AC

Item Bytes | Field Name | Description of Field
--- | --- | ---
1 | Relational-retrieval | This byte field defines relational-retrieval support for the Association-acceptor. It shall be encoded as an unsigned binary integer and shall use one of the following values 0 - relational-retrievals not supported 1 - relational-retrievals supported
2 | Enhanced Multi-Frame Image Conversion | This byte field defines whether or not the Attribute Query/Retrieve View (0008,0053) shall be used to adjust the view returned in queries to consider conversion to or from Enhanced Multi-Frame Images. It shall be encoded as an unsigned binary integer and shall use one of the following values 0 - Query/Retrieve View not supported 1 - Query/Retrieve View supported

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DICOM PS3.4 2021c - Service Class Specifications