DICOM PS3.4 2021b - Service Class Specifications

Q.2 DIMSE-C Service Group (Current)
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## Q.2 DIMSE-C Service Group

One DIMSE-C Service is used in the construction of SOP Classes of the Relevant Patient Information Query Service Class. The following DIMSE-C operation is used.

- C-FIND

### Q.2.1 C-FIND Operation

SCPs of the Relevant Patient Information Query Service Class are capable of processing queries using the C-FIND operation as described in PS3.7. The C-FIND operation is the mechanism by which queries are performed. The SCP shall provide Relevant Patient Information for at most one matching patient in the C-FIND response.

#### Q.2.1.1 C-FIND Service Parameters

##### Q.2.1.1.1 SOP Class UID

The SOP Class UID identifies the Relevant Patient Information Model and Template against which the C-FIND 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-FIND operation.

##### Q.2.1.1.2 Priority

The Priority Attribute defines the requested priority of the C-FIND operation 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.

##### Q.2.1.1.3 Identifier

Both the C-FIND request and response contain an Identifier encoded as a Data Set (see PS3.5).

###### Q.2.1.1.3.1 Request Identifier Structure

An Identifier in a C-FIND request shall contain:

- Key Attributes with values to be matched against the values of Attributes specified in the SOP Class.

- Content Template Sequence (0040,A504), which shall include a single sequence item containing the Template Identifier (0040,DB00) and Mapping Resource (0008,0105) Attributes, to identify the template structure to use in the matching C-FIND responses.

- Conditionally, the Attribute Specific Character Set (0008,0005). This Attribute shall be included if expanded or replacement character sets may be used in any of the Attributes in the Request Identifier. It shall not be included otherwise.

The Key Attributes and values allowable for the query are defined in the SOP Class definition for the Relevant Patient Information Model.

###### Q.2.1.1.3.2 Response Identifier Structure

The C-FIND response shall not contain Attributes that were not in the request or specified in this section.

An Identifier in a C-FIND response shall contain:

- Key Attributes with values corresponding to Key Attributes contained in the Identifier of the request.

- Content Template Sequence (0040,A504), which shall include a single sequence item containing the Template Identifier (0040,DB00) and Mapping Resource (0008,0105) Attributes, to identify the template structure used in the C-FIND response. The values shall be the same as specified in the Request Identifier.

- Conditionally, the Attribute Specific Character Set (0008,0005). This Attribute shall be included if expanded or replacement character sets may be used in any of the Attributes in the Response Identifier. It shall not be included otherwise. The C-FIND SCP is not required to return responses in the Specific Character Set requested by the SCU if that character set is not supported by the SCP. The SCP may return responses with a different Specific Character Set.

###### Q.2.1.1.3.3 Relevant Patient Information Templates

Templates used in the Relevant Patient Information query are defined in PS3.16.

The template specified in the Request Identifier shall not use by-reference relationships.

##### Q.2.1.1.4 Status

Table Q.2-1 defines the status code values that might be returned in a C-FIND response. General status code values and fields related to status code values are defined for C-FIND DIMSE Service in PS3.7.

Table Q.2-1. C-FIND Response Status Values

Service Status | Further Meaning | Status Codes | Related Fields
--- | --- | --- | ---
Failure | Refused: Out of resources | A700 | (0000,0902)
Error: Data Set does not match SOP Class | A900 | (0000,0901) (0000,0902)
Failed: Unable to process | C000 | (0000,0901) (0000,0902)
Failed: More than one match found | C100 | (0000,0901) (0000,0902)
Failed: Unable to support requested template | C200 | (0000,0901) (0000,0902)
Cancel | Matching terminated due to Cancel request | FE00 | None
Success | Success. Matching is complete - No final Identifier is supplied. | 0000 | None
Pending | Current Match is supplied. | FF00 | Identifier

### Note

Status Codes are returned in DIMSE response messages (see PS3.7). The code values stated in column "Status Codes" are returned in Status Command Element (0000,0900).

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DICOM PS3.4 2021b - Service Class Specifications