This page is part of the DICOM® SR to FHIR Resource Mapping IG (v1.0.0-ballot: STU1 Ballot 1) based on FHIR (HL7® FHIR® Standard) v5.0.0. . For a full list of available versions, see the Directory of published versions

Architecture

This chapter describes the architecture of this implementation guide.

Profiles & Extensions

Resource Profiles

Observation

The mapping of the core DICOM SR measurement groups, measurements and qualitative analysis content items are covered by the following resource profiles:

• Imaging Measurement Group profiles the Observation resource representing DICOM SR measurement group templates:
  • DTID 1410 “Planar ROI Measurements and Qualitative Evaluations”
  • DTID 1411 “Volumetric ROI Measurements and Qualitative Evaluations”
  • DTID 1501 “Measurement and Qualitative Evaluation Group”
• Imaging Measurement profiles the Observation resource representing imaging measurements extracted from DICOM SR measurement templates:
  • DTID 300 “Measurement”
  • DTID 1419 “ROI Measurements”

• Derived Imaging Measurement profiles the Observation resource representing the DICOM SR derived measurement template DTID 1420 “Measurements Derived From Multiple ROI Measurements”

• Imaging Qualitative Evaluation profiles the Observation resource representing qualitative evaluation content items

The above resource profiles depend on the following resource profiles:

ImagingSelection

• Image Region – 2D profiles the ImagingSelection resource representing a referenced 2D image region content item CID 111030 "Image Region"
• Image Region – 3D profiles the ImagingSelection resource representing a referenced 3D image region content item CID 111030 "Image Region"
• Referenced Segment profiles the ImagingSelection resource representing a referenced segment content item CID 121191 "Referenced Segment"
• Referenced Segmentation Frame profiles the ImagingSelection resource representing a referenced segmentation frame content item CID 121214 "Referenced Segmentation Frame"
• Region In Space profiles the ImagingSelection resource representing a referenced RT Structure Set content item CID 130488 "Region in Space"
• Volume Surface profiles the ImagingSelection resource representing a referenced volume surface content item CID 121231 "Volume Surface"
• Real World Value Map profiles the ImagingSelection resource representing a referenced real world value map content item CID 126100 "Real World Value Map used for measurement"
• Illustration of ROI profiles the ImagingSelection resource representing a referenced ROI illustration content item CID 121200 "Illustration of ROI"
• Visual explanation profiles the ImagingSelection resource representing a referenced visual explanation content item CID 130401 "Visual explanation

Device

• Algorithm Identification profiles the Device resource representing the DICOM SR template DTID 4019 “Algorithm Identification”
• General Equipment profiles the Device resource representing the DICOM General Equipment Module DICOM PS3.3 C.7.5.1 General Equipment Module

BodyStructure

• Finding Site profiles the BodyStructure resource representing a finding site content item CID SCT#363698007 "Finding Site"

Supporting DataType Profiles

There is no special supporting DataType profiles defined by this IG.

Supporting Extensions

There is no special supporting extensions defined by this IG.

Profile Relationships

DICOM SR Basics

The content of a DICOM SR is a tree of "content items". Each content item has:

• a coded "Concept Name" describing the content item
• a "Value Type"
• a value (for most value types)
• zero or more children, each of which is also a content item¹

The content item value types relevant to this implementation guide are:

• CONTAINER: a container with children but no value
• NUM: a numerical value with units
• TEXT: a textual value
• CODE: a coded value
  • Note that a CODE content item has a coded concept name and a coded value

Relationship to DICOM SR TID 1500 Measurement Report

This implementation guide maps content items contained within the DICOM TID 1500 Measurement Report to FHIR resources.

All mapped content items are children of the following CONTAINER content items:

Container Concept Name	Child FHIR Resource Profile	Notes
DCM#126010 "Imaging Measurements"	Imaging Measurement Group	See Imaging Measurement Group relationship
DCM#126011 "Derived Imaging Measurements"	Derived Imaging Measurements	See Derived Imaging Measurements relationship
UMLS#C0034375 "Qualitative Evaluations"	Imaging Qualitative Evaluation	See Imaging Qualitative Evaluations relationship

e.g. the children of the CONTAINER with a Concept Name of DCM#126010 "Imaging Measurements" are mapped to Measurement Group Observations.

Imaging Measurement Group Relationship

An Imaging Measurement Group CONTAINER contains 0-n NUM content items representing numerical measurements. Each of these is mapped to an Imaging Measurement Observation.

An Imaging Measurement Group CONTAINER contains 0-n TEXT or CODE content items representing qualitative evaluations. Each of these is mapped to an Imaging Qualitative Evaluation Observation.

The Imaging Measurement Group CONTAINER is mapped to a Imaging Measurement Group Observation.

The Imaging Measurement Group Observation hasMember element references the child Imaging Measurement and Imaging Qualitative Evaluation Observations.

Note: Not all TEXT or CODE content items contained within the Imaging Measurement Group represent qualitative evaluations.

A TEXT or CODE child content item should only be interpreted as a qualitative evaluation if it does not have a Concept Name from the following list:

• DCM#112039 "Tracking Identifier"
• DCM#121071 "Finding"
• DCM#130400 "Geometric purpose of region"
• NCIt#C67447 "Activity Session"
• SCT#276214006 "Finding Category"
• SCT#363698007 "Finding Site"
• SCT#370129005 "Measurement Method"

Derived Imaging Measurements Relationship

A Derived Imaging Measurement CONTAINER contains 0-n NUM content items representing derived numerical measurements. Each of these is mapped to a Derived Measurement Observation.

A Derived Imaging Measurement CONTAINER contains 0-n Imaging Measurement Group CONTAINER content items. Each of these is mapped to an Imaging Measurement Group Observation (see Imaging Measurement Group relationship).

The Derived Imaging Measurements Observation derivedFrom element references the child Imaging Measurement Group Observations.

Imaging Qualitative Evaluations Relationship

An Imaging Qualitative Evaluations CONTAINER contains 0-n TEXT or CODE content items representing qualitative evaluations. Each of these is mapped to an Imaging Qualitative Evaluation Observation.

Device Relationship

A FHIR Observation can only have a single device value. However, a DICOM SR can have two types of devices:

• The equipment that created the SR
• An algorithm used to create the Observation

The DICOM SR General Equipment Module attributes are mapped to an Equipment Device.

If an Imaging Measurement Group, Imaging Measurement or Imaging Qualitative Evaluation has a child with Concept Name DCM#111001 "Algorithm Name" then it is mapped to an Algorithm Identification Device.

All algorithm devices will populate use the Equipment Device to populate the parent element.

If an Imaging Measurement Group, Imaging Measurement or Imaging Qualitative Evaluation does not have a defined device then the device element references the Equipment Device.

e.g.

• If an Imaging Qualitative Evaluation is part of an Imaging Measurement Group:
  • If both have a defined Algorithm Identification Device, both devices will be created and each will have the Equipment Device as its parent.
  • If the Imaging Qualitative Evaluation does not have a defined Algorithm Identification Device it's device element will reference the Equipment Device

Other Resource Relationships

All DICOM SOP Instances include information relating to the patient, service request, procedure, etc.

Typically, these resources are managed by the EMR and the imaging system is not able to create or update these resources in the FHIR server.

Therefore, this implementation guide assumes that these resources already exist in the destination FHIR server and does not include a full mapping between their DICOM representation and their FHIR representation.

Instead, it specifies the identifier mapping to allow newly-created resources to be associated with the appropriate existing FHIR resources.

See DICOM SR Information Object Definition (IOD) Mapping to FHIR and DICOM SR Document Information Entity (IE) Mapping to FHIR.

Actors

Terminology

Security Consideration

Exchanging imaging measurement report resources makes use of patient-specific information which could be exploited by malicious actors resulting in exposure of patient data. For these reasons, all data exchange between the different actors must be secured appropriately with access to limited authorized individuals, data protected in transit, and appropriate audit measures taken.

Implementers SHOULD be aware of these security considerations associated with FHIR transactions, particularly those related to:

• Communications
• Authentication
• Authorization/Access Control
• Audit Logging
• Digital Signatures
• Security Labels
• Narrative

These security requirements are highlighted in the context of this IG:

• Systems SHALL keep audit logs of the various transactions. Some auditing workflows can be used like IHE ATNA or Restful ATNA.
• Systems SHALL use TLS version 1.2 or higher for all transmissions not taking place over a secure network connection. IHE ATNA may be followed for the TLS usage.
• Systems SHALL conform to FHIR Communications Security requirements.
• Systems SHALL implement consent requirements per their country, state, local, and institutional policies.