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Radiology Scheduled Workflow (SWF.b)

Radiology is the largest imaging service. It uses a Radiology Information System (RIS) for requests, scheduling and reporting, and a PACS for images. Its workflow is described by IHE Radiology Scheduled Workflow (SWF.b).

References

• IHE Radiology (RAD) profiles
• IHE RAD Scheduled Workflow.b (SWF.b) supplement - Trial Implementation
• HL7 Europe Imaging Report - FHIR model of the imaging report
• NICIP code set - NHS England
• Diagnostic Imaging Dataset (DID) - NHS England

The Imaging Pathway

Seen from the patient and the referrer, a radiology examination is a short pathway embedded in the wider clinical (or cancer) pathway: the clinician asks a question, imaging answers it, and the clinician acts on the answer.

flowchart LR
    A[Clinical assessment<br/>GP, outpatient, ED, ward] --> B[Request<br/>Order Comms + decision support]
    B --> C[Vetting and justification<br/>radiologist / radiographer]
    C -->|justified| D[Protocol and schedule<br/>booking, hot / cold slots]
    C -->|not justified| A
    D --> E[Acquisition<br/>modality, images to PACS]
    E --> F[Reporting<br/>radiologist / reporting radiographer]
    F --> G[Report to referrer<br/>urgent / unexpected findings alerted]
    G --> H[Acknowledge and act<br/>referrer, MDT]

Reporting turnaround times (NHS England, effective 9 August 2023), measured from the examination to a verified report being available to the referrer; no report should take longer than 4 weeks from image acquisition:

Ultrasound and interventional radiology are reported at the time of the examination. Fluoroscopy and nuclear medicine (including PET-CT) follow the CT/MRI categories. See the guidance for the full table.

Further references for the pathway:

• GIRFT Radiology national specialty report (November 2020) - including recommendation 9: all trusts to meet RCR IT standards, Order Comms as the standard request method, new PACS/RIS to meet RCR standards for image and report sharing
• NHS England Diagnostic imaging network implementation guide
• NICE has no radiology-wide pathway guidance; imaging appears within condition-specific guidance such as NG12 (suspected cancer)

Scheduled Workflow

sequenceDiagram
    participant OP as Order Placer<br/>EPR / Order Comms
    participant OF as Order Filler<br/>RIS
    participant MOD as Acquisition Modality<br/>CT, MR, US, ...
    participant IM as Image Manager / Archive<br/>PACS / VNA
    participant RC as Report Creator / Manager<br/>RIS reporting

    OP ->> OF: Placer Order Management [RAD-2]<br/>OMG^O19 (or FHIR Message O19)
    OF -->> OF: Vetting (justification), protocol, schedule
    OF ->> OP: Filler Order Management [RAD-3]<br/>OMG^O19 (status, or FHIR Message O19)
    OF ->> IM: Procedure Scheduled [RAD-4] / Update [RAD-13]<br/>OMI^O23
    MOD ->> OF: Query Modality Worklist [RAD-5]<br/>DICOM MWL
    OF -->> MOD: Scheduled procedure step
    MOD -->> MOD: Acquire images
    MOD ->> OF: Modality Procedure Step In Progress / Completed<br/>[RAD-6] / [RAD-7] (DICOM MPPS)
    MOD ->> IM: Modality Images Stored [RAD-8]<br/>DICOM C-STORE
    MOD ->> IM: Storage Commitment [RAD-10]
    IM ->> OF: Instance Availability Notification [RAD-49] (optional)<br/>or Image Availability Query [RAD-11]
    RC ->> IM: Retrieve Images [RAD-16]
    RC -->> RC: Radiologist / reporting radiographer reports
    RC ->> OP: Send Imaging Result [RAD-128]<br/>ORU^R01 (or FHIR Message R01)

SWF.b requires HL7 v2.5.1 for its HL7 transactions (the version the NW GMSA IG also uses). Transactions covered by this guide:

Indicative mapping of the main SWF.b actors to typical NHS systems:

Identifiers that tie the workflow together:

In FHIR these appear as ServiceRequest.identifier (placer and accession), ImagingStudy.identifier (Study Instance UID and accession) and DiagnosticReport.identifier - see FHIR Resources, which also lists the report data items described by the Royal College of Radiologists, mapped to FHIR, HL7 v2 and DICOM.

Procedure Codes

Radiology procedures in England are coded with NICIP (National Interim Clinical Imaging Procedure) codes, mapped to SNOMED CT:

• NICIP is a national set of codes and descriptions for imaging procedures, for use in all imaging department systems. A NICIP code identifies both the modality and the body site.
• Each NICIP code is mapped to SNOMED CT (the UK Diagnostic Imaging Procedure subset). NICIP, with and without SNOMED CT maps, is distributed through TRUD, with releases on 1 April and 1 October.
• NHS England has consulted on withdrawing NICIP in favour of SNOMED CT only. The current status is To confirm.

This guide codes NICIP with the Interweave NICIP CodeSystem - the NICIP code is required on the request and used on the report, as in the Interweave FHIR IG. See Terminology.

Diagnostic Imaging Dataset

The Diagnostic Imaging Dataset (DID) is the national collection of radiology activity, submitted monthly from RIS. It records the test (NICIP and SNOMED CT codes), dates (request, test, report) and patient details. It is radiology activity data, not the report content.

Out of Scope

• Detailed HL7 v2 message profiles for radiology orders and results
• DICOM conformance of modalities and PACS
• Radiation dose management