The Alternate Representation Sequence (0008,3001) encodes a reference to an alternate encoding of the composite image identified in the Query response item. This alternate encoding may utilize a different SOP Class or have different image quality characteristics, but it shall be the same image.
Note: The Alternate Representation Sequence (0008,3001)allows the query response about an original image to reference a lossy compressed version, and vice versa.
An image may be lossy compressed, e.g., for long-term archive purposes, and its SOP Instance UID changed. An application processing a SOP Instance that references the original image UID, e.g., a Structured Report, may query the C-FIND SCP for the image. The SCP returns a reference to an accessible version of the image even if the original SOP Instance is no longer available.
The Alternate Representation Sequence (0008,3001), if present in a Query Request Identifier, shall be zero-length, or shall contain a single zero-length Item. That is, only Universal Matching is defined for this attribute.
The Alternate Representation Sequence (0008,3001), if present in the Query Response Identifier, may include zero or more Items. Each Alternate Representation Sequence Item in the Query Response Identifier shall include
the Series Instance UID (0020,000E) if the alternately encoded image is in a different Series.
the Purpose of Reference Code Sequence (0040,A170), which shall describe the nature of the alternate encoding of the image. The Purpose of Reference Code Sequence (0040,A170) shall include only one Item. The Baseline Context Group for this Code Sequence is CID 7205.
C.184.108.40.206 Scope of the GET and MOVE Commands and Sub-Operations
A C-MOVE or C-GET request may be performed to any level of the Query/Retrieve Model. However, the transfer of Stored SOP Instances shall always take place at the Composite object instance level. A C-MOVE or C-GET where the Query/Retrieve level is the:
PATIENT level indicates that all composite object instances related to a Patient shall be transferred.
STUDY level indicates that all composite object instances related to a Study shall be transferred.
SERIES level indicates that all composite object instances related to a Series shall be transferred.
IMAGE level indicates that selected individual composite object instances shall be transferred.
Note: In the Baseline behavior, more than one entity may be retrieved if the Query/Retrieve Level is IMAGE, SERIES or STUDY, using List of UID matching, but only Single Value Matching value may be specified for Patient ID (0010,0020).