DICOM PS3.4 2020b - Service Class Specifications

Y.4.2 C-GET Operation (Current)
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### Y.4.2 C-GET Operation

SCUs of the Composite Instance Root Retrieve Service shall generate retrievals using the C-GET operation as described in PS3.7. The C-GET operation allows an application entity to instruct another application entity to transfer stored SOP Instances or new SOP Instances derived from such stored SOP Instances to the initiating application entity using the C-STORE operation. Support for the C-GET service shall be agreed upon at Association establishment time by both the SCU and SCP of the C-GET in order for a C-GET operation to occur over the Association. The C-STORE Sub-operations shall be accomplished on the same Association as the C-GET operation. Hence, the SCP of the Query/Retrieve Service Class serves as the SCU of the Storage Service Class.

### Note

The Application Entity that receives the stored SOP Instances is always the originator of the C-GET operation.

A C-GET request may be performed to any level of the Composite Instance Root Retrieve Information Model, and the expected SCP behavior depends on the level selected.

#### Y.4.2.1 C-GET Service Parameters

##### Y.4.2.1.1 SOP Class UID

The SOP Class UID identifies the Query/Retrieve Information Model against which the C-GET is to be performed. Support for the SOP Class UID is implied by the Abstract Syntax UID of the Presentation Context used by this C-GET operation.

##### Y.4.2.1.2 Priority

The Priority Attribute defines the requested priority of the C-GET operation and corresponding C-STORE sub-operations with respect to other DIMSE operations being performed by the same SCP.

Processing of priority requests is not required of SCPs. Whether or not an SCP supports priority processing, and the meaning of the different priority levels shall be stated in the Conformance Statement of the SCP. The same priority shall be used for all C-STORE sub-operations.

##### Y.4.2.1.3 Identifier

The C-GET request shall contain an Identifier. The C-GET response shall conditionally contain an Identifier as required in Section C.4.3.1.3.2.

### Note

The Identifier is specified as U in the definition of the C-GET primitive in PS3.7 but is specialized for use with this service.

###### Y.4.2.1.3.1 Request Identifier Structure

An Identifier in a C-GET request shall contain:

- the Query/Retrieve Level (0008,0052) that defines the level of the retrieval

- SOP Instance UID(s) (0008,0018)

- One of the Frame Range Keys if present in the Information Model for the level of the Retrieval

- Conditionally, the Attribute Query/Retrieve View (0008,0053). This Attribute may be included if Enhanced Multi-Frame Image Conversion has accepted during Association Extended Negotiation. It shall not be included otherwise.

Specific Character Set (0008,0005) shall not be present.

The Keys at each level of the hierarchy and the values allowable for the level of the retrieval shall be defined in the SOP Class definition for the Query/Retrieve Information Model.

##### Y.4.2.1.4 Status

The status code values that might be returned in a C-GET response shall be as specified in Table Y.4-2

Table Y.4-2. C-GET Response Status Values for Composite Instance Root Retrieve

Service Status | Further Meaning | Status Codes | Related Fields
--- | --- | --- | ---
Failure | Refused: Out of resources - Unable to calculate number of matches | A701 | (0000,0902)
Refused: Out of resources - Unable to perform sub-operations | A702 | (0000,1020) (0000,1021) (0000,1022) (0000,1023)
Error: Data Set does not match SOP Class | A900 | (0000,0901) (0000,0902)
Failed: Unable to process | Cxxx | (0000,0901) (0000,0902)
Failed: None of the frames requested were found in the SOP Instance | AA00 | (0000,0902)
Failed: Unable to create new object for this SOP Class | AA01 | (0000,0902)
Failed: Unable to extract frames | AA02 | (0000,0902)
Failed: Time-based request received for a non-time-based original SOP Instance. | AA03 | (0000,0902)
Failed: Invalid Request | AA04 | (0000,0901) (0000,0902)
Cancel | Sub-operations terminated due to Cancel Indication | FE00 | (0000,1020) (0000,1021) (0000,1022) (0000,1023)
Warning | Sub-operations Complete - One or more Failures or Warnings | B000 | (0000,1020) (0000,1021) (0000,1022) (0000,1023)
Success | Sub-operations Complete - No Failures or Warnings | 0000 | (0000,1020) (0000,1021) (0000,1022) (0000,1023)
Pending | Sub-operations are continuing | FF00 | (0000,1020) (0000,1021) (0000,1022) (0000,1023)

##### Y.4.2.1.5 Number of Remaining Sub-Operations

Inclusion of the Number of Remaining Sub-operations shall be as specified in Section C.4.3.1.5

##### Y.4.2.1.6 Number of Completed Sub-Operations

Inclusion of the Number of Completed Sub-operations shall be as specified in Section C.4.3.1.6

##### Y.4.2.1.7 Number of Failed Sub-Operations

Inclusion of the Number of Failed Sub-operations shall be as specified in Section C.4.3.1.7

##### Y.4.2.1.8 Number of Warning Sub-Operations

Inclusion of the Number of Warning Sub-operations shall be as specified in Section C.4.3.1.8.

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DICOM PS3.4 2020b - Service Class Specifications