Two Standards, Two Jobs
HL7 carries patient, order and report data between hospital systems. DICOM carries the images and the modality worklist. Pacslink uses HL7 version 2 to connect its HMIS, EMR, RIS, PACS and LIS with each other and with third-party systems, and DICOM 3.0 between the RIS, PACS and imaging modalities.
The result is that a patient registered once in the HMIS flows through radiology without re-typing, and every signed report returns to the right patient record.
HL7 v2 Messages
Interfaces are agreed per project in an interface specification. The message types used in a typical radiology integration are listed below.
| Message | Direction | Purpose |
|---|---|---|
| ADT^A04 / ADT^A01 | HMIS → RIS | Patient registration or admission |
| ADT^A08 | HMIS → RIS | Patient demographic updates |
| ORM^O01 | HMIS / EMR → RIS | New, changed or cancelled radiology orders |
| ORU^R01 | RIS → HMIS / EMR | Signed radiology reports returned to the patient record |
| ACK | Both directions | Acknowledgement of each message received |
The Integrated Radiology Workflow
- The patient is registered in the HMIS and the doctor orders a scan.
- The HMIS sends the order to the RIS as an HL7 message.
- The RIS publishes a DICOM modality worklist, so the CT, MRI or X-ray machine picks up the correct patient.
- The modality sends the images to the PACS over DICOM.
- The radiologist reads the study in the web DICOM viewer and signs the report in the RIS.
- The RIS returns the report to the HMIS or EMR as an HL7 result message.
HL7 FHIR
HL7 FHIR exposes healthcare data through modern web APIs (REST and JSON) and is increasingly used for mobile apps and data sharing between organisations. If a FHIR interface is a requirement for your project, raise it during scoping so the integration approach, resources and security model can be agreed up front.
Laboratory and Third-Party Systems
Pacslink LIS interfaces directly with laboratory analysers and machines, and lab orders and results flow between the LIS and HMIS in the same way as radiology. Existing third-party HMIS, EMR or billing systems are connected over HL7 v2 after their interface specification has been reviewed.
How an Integration Project Runs
- Scoping: list the systems, message types and data each interface needs.
- Interface specification: agree message fields, identifiers and code tables with each vendor.
- Testing: run test patients end to end, from order to signed report.
- Go-live and monitoring: switch over, with support from our Lahore team.
