Module order 

Imaging-order identifiers as carried by ORM^O01, OMI^O23 and ORU^R01 messages.

The four fields that link an HL7 message to a DICOM study, per the IHE Radiology Technical Framework (Scheduled Workflow) and the HL7 v2.5.1 imaging order messages:

Field	Candidates, in precedence order	DICOM counterpart
Patient identifier	PID-3.1 (first repetition)	Patient ID (0010,0020)
Accession number	OBR-18 (Placer Field 1), then IPC-1.1	Accession Number (0008,0050)
Requested procedure ID	OBR-19 (Placer Field 2), then IPC-2.1	Requested Procedure ID (0040,1001)
Study instance UID	IPC-3.1, then ZDS-1.1, then an OBX carrying DCM 110180	Study Instance UID (0020,000D)

Three ways the study UID travels, and all three occur in the wild:

• IPC (Imaging Procedure Control) is a standard segment of the imaging order messages (OMI^O23, HL7 2.5.1 and later): IPC-1 is the accession identifier, IPC-2 the requested procedure ID, IPC-3 the Study Instance UID, IPC-4 the scheduled procedure step ID. Several procedure steps give several IPC segments whose IPC-3 must agree.
• ZDS is a vendor-defined Z-segment from the IHE profile used with ORM^O01 on older interfaces. ZDS-1 is uid^^Application^DICOM; only the first component is the UID. Many sites never populate it.
• An OBX in an ORU^R01 image-availability notification whose OBX-3 is the DICOM code 110180 (Study Instance UID, coding system DCM), with the UID in OBX-5. This is how a PACS tells the RIS that images have arrived, and it is the only place some integration engines look.

When sources disagree, the first in precedence is used and a Warning::ConflictingStudyUid is recorded on the Order.

In practice the accession number is the key most RIS and order workflows actually use; the study UID is exact when present but is sometimes derived or regenerated by the archive. The linkage logic that consumes an Order should therefore compare both and say when they disagree with each other, not only fall from one to the other.

Structs

Order

The identifiers extracted from an order message.

Enums

OrderField

One of the four order identifiers.

StudyUidSource

Which segment supplied the study instance UID.

Constants

DCM_STUDY_INSTANCE_UID

DICOM code for “Study Instance UID” in coding scheme DCM (PS3.16).