MedMij FHIR Implementation Guide: Images
1 Introduction
This page describes the exchange of images within MedMij. Contrary to other MedMij use cases, we have not identified an existing information standard nor any specifically applicable HCIM? models. To achieve exchange of images, MedMij adopts as much as possible from existing standards, such as the DICOM standard and the Mobile access to Health Documents (MHD) profile from Integrating the Healthcare Enterprise (IHE) that defines a RESTful/HTTP interface to an XDS environment using HL7 FHIR STU3 resources.
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This specification builds off IHE MHD which usually serves as an IHE XDS compatible frontend. However having an XDS network on either sending or receiving side is not a requirement per this specification. |
The specification currently consists of one use case, that covers sending an image by a patient to a healthcare provider. We anticipate adding a use case to retrieve images by the patient in a future version of this specification. This will most likely will be based on DICOMweb™, which is the DICOM standard for web-based medical imaging based on RESTful services.
Note: This implementation guide builds on the general guidelines described in the use case overarching principles.
2 Actors and transactions involved
Table 1 shows the relevant actors, systems and FHIR capability statements in a MedMij context. The capability statements demonstrate the minimum requirements to be in conformance with the described use cases.
| Persons | Systems | FHIR Capability Statements | |||
|---|---|---|---|---|---|
| Name | Description | Name | Description | Name | Description |
| Patient | The user of a personal healthcare environment. | PHR | Personal health record |  CapabilityStatement: Client
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Image FHIR Client requirements |
| Healthcare Provider | The user of a XIS | XIS | Healthcare information system | CapabilityStatement: Server
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Image FHIR Server requirements |
Table 1. Actors, systems and FHIR capability statements
3 Boundaries and Relationships
The use case where an image is sent from a PHR to a XIS is influenced by the IHE MHD profile with regards to the PHR message semantics and mandatory elements. The main deviation of these use-case specifications is the use of the FHIR Media resource instead of the DocumentReference resource. Although the DocumentReference is in line with the requirements of persisting content in an XDS network and the DocumentReference can handle images, the Media resource is more appropriate and specific for the exchange of images. The Media resource has additional, relevant, (medical related) elements compared to the DocumentReference. These are the Media elements view, reasonCode, bodySite, device and to a lesser extent the height and width elements. In addition, the Media resource has a reference coming from the DiagnosticReport that may be of value for further development of the MedMij information standard for images.
A XIS can possibly act within a XDS network. MedMij information standards have the primary objective to enable standardized communication between the parties that act within MedMij. As a secondary objective, exchange with parties that are part of a XDS networks are taken into account. For this objective, the PHR will need to provide additional meta information to the Media resource. The additional meta information allows XIS actors to index an image properly within a XDS network. The XIS is responsible for converting the PHR message into a XDS DocumentEntry. A mapping from the Media resource to the mandatory metadata elements of the IHE MHD DocumentReference resource is provided. The IHE MHD and general IHE XDS profiles will provide the information needed to produce a successful DocumentEntry for an image.
4 Use case: send image from a PHR to a XIS
This FHIR implementation guide assumes that the PHR system is able to make a connection to the right XIS that contains the patient's information. It does not provide information on finding the right XIS nor does it provide information about security. Moreover, each transaction is performed in the context of a specific authenticated patient, for whose context (token) has been established using the authentication mechanisms described in the 'Afsprakenstelsel'. Each XIS Gateway is required to perform filtering based on the patient associated with the context for the request, so only the records associated with the authenticated patient are returned. For this reason, search parameters should not be included for patient identification.
4.1 Introduction
This use case describes the minimal required technical functionalities in order to exchange an image made by the patient to a healthcare provider. Typical process flow would be:
- Patients creates, downloads or receives an image and uploads it to his PHR.
- The PHR sends the image to the chosen XIS system.
- Potentially the patient needs to provide sufficient metadata concerning the image.
- A healthcare provider views the image in his XIS.
This use case presumes made agreements between the patient and healthcare provider. Besides a technical answer by the XIS of the healthcare provider, no answer to the patient is expected.
The following technical specifications will concern the process mentioned in bullet 2.
4.2 Actors
| Transaction group | Transaction | Actor | Role |
|---|---|---|---|
| Send Image Bundle (PUSH) | Send image bundle request | Patient (using a PHR) | Sends image to the XIS |
| Receive image bundle response | Healthcare professional (using a XIS) | Receives image from PHR |
4.3 Invocations
4.3.1 Client - PHR request
When the patient (PHR) wants to send one or more images, it issues a send image bundle request message.
The PHR initiates a FHIR transaction by sending an HTTP POST request composed of a FHIR Bundle Resource containing one List resource, one or more FHIR Media resources, one or more Binary resources, one Patient resource, and zero or one Practitioner resource to the XIS recipient.
The PHR executes an HTTP POST against the XIS's base endpoint as shown below.
POST [base]
The PHR shall guarantee consistency of all FHIR resource elements with the requirements specified in the profiles for List, Media, Patient, Practitioner, PractitionerRole and Organization resources. References to these profiles are provided in list of StructureDefinitions.
4.3.1.1 Textual Requirements
- The Bundle.type shall be 'transaction'.
- The Bundle contains one List resource that has one to three references to a Media resource.
- The Media.content.attachment.url points at the image content, which shall be included in the Bundle as a Binary resource. See FHIR Resolving references in Bundles at the FHIR specification and use within MedMij at the MedMij Use case overarching principles.
- The Media has one version specific identifier. This identifier is discriminated from potential other identifiers by a fixed 'official' value at identifier.use.
- Referenced Resources (for example Patient, Practitioner and PractitionerRole) shall be included in the Bundle.
- Accompanying text from the patient for the image and/or collection of images shall be placed in the Media.note and List.note respectively.
4.3.2 Server - XIS response
The XIS shall process the bundle atomically.
4.3.2.1 Response message
The XIS response message shall be sent when a success or error condition needs to be communicated. Success is only indicated once the image(s) and accompanying resources are received and completely processed and persisted as appropriate to the XIS configuration. The XIS returns an HTTP Status code appropriate to the processing outcome, conforming to the transaction specification requirements as specified in the FHIR specification.
To enable the PHR to know the outcome of processing the transaction, and the identities assigned to the resources by the XIS, the XIS shall return a Bundle, with type set to transaction-response, that contains one entry for each entry in the request, in the same order as received, with the Bundle.entry.response.outcome indicating the results of processing the entry. The XIS shall comply with FHIR Bundle transaction-response and the HTTP transaction-response specifications.
4.3.3 Server - XIS & XDS
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This non-normative section provides advice for receiving XIS actors that want to persist images in an XDS network. MedMij information standards concern the exchange of healthcare information between PHR and XIS systems that act within the MedMij network. The possible backend of those systems is out of scope for the normative section of the information standard. |
If the receiving XIS is part of a XDS network, it may need to convert the PHR request message into a proper message for the IHE "Provide and Register Document Set-b [ITI-41]" transaction. The XIS shall create appropriate metadata from the resources in the FHIR Bundle. The PHR provides the minimally required metadata. A mapping is shown below to assist in creating the XDS entry. The FHIR Media resource is mapped to the mandatory elements in the IHE MHD Profile on "DocumentReference with Comprehensive (aka XDS-on-FHIR) Metadata". IHE MHD defined these elements as a minimum for a XDS DocumentEntry. The Media and List profiles, provided in the list of StructureDefinitions, contain mappings to a XDS DocumentEntry and XDS Folder Metadata Attributes respectively. Some FHIR elements do not translate to XDS concepts; the handling of these elements is left to the implementer of the XIS.
Upon successful conversion of the FHIR Bundle to XDS metadata, the XIS shall execute the Provide and Register Document Set-b [ITI-41] transaction. The transaction result and any error or warning messages shall be reported to the PHR. The XIS is responsible for translating the XDS response to the appropriate HTTP Status Code and FHIR OperationOutcome Resource in the Send Image Bundle Response Message.
4.3.3.1 Mapping Media to mandatory IHE MHD DocumentReference elements needed for XDS DocumentEntry
| IHE MHD Profile on DocumentReference with Comprehensive (aka XDS-on-FHIR) Metadata | Media for images, used by the PHR | Implementation notes for XIS & XDS |
|---|---|---|
| DocumentReference.masterIdentifier | Media.identifier and identifier.use = 'official' | |
| DocumentReference.status | Fixed value "current". | |
| DocumentReference.type | Media.type | Fixed LOINC code: 72170-4 Photographic image Unspecified body region Document. |
| DocumentReference.class | Fixed SNOMED code: 9491000146107 - Imaging documentation (record artifact). | |
| DocumentReference.subject | Media.subject | |
| DocumentReference.indexed | Media.occurrenceDateTime | |
| DocumentReference.securityLabel | Media.meta.security | If no value is present 'normal' should be used as default. |
| DocumentReference.content | Media.content | |
| DocumentReference.content.attachment | Media.content.attachment | |
| DocumentReference.content.attachment.contentType | Media.content.attachment.contentType | Possible media content types: JPEG, PNG, GIF, JP2. |
| DocumentReference.content.attachment.url | Media.content.attachment.url | |
| DocumentReference.content.attachment.size | Media.content.attachment.size | |
| DocumentReference.content.attachment.hash | Media.content.attachment.hash | |
| DocumentReference.content.format | Fixed value "mimeType Sufficient". |
A number of fixed values can be used in indexing to a XDS network based on an image sent by a patient. These are status, type, class, security (if no value is given in the Media.meta.security element) and format.
4.3.3.2 IHE MHD StructureDefinitions
IHE has defined StructureDefinitions and other Conformance Resources applicable to this use case. The FHIR Implementation Guide on the IHE MHD wiki lists these StructureDefinitions.
However, due to errors encountered, that IHE did not intend to fix in STU3, Nictiz has fixed the errors and re-published the IHE.MHD profiles in the Nictiz namespace. Note that IHE originally created two profiles, one for Query DocumentReference and one for Provide DocumentReference which are identical to each other. For usability purposes, these two profiles have been merged.
- http://nictiz.nl/fhir/StructureDefinition/IHE.MHD.Minimal.ProvideDocumentBundle
- http://nictiz.nl/fhir/StructureDefinition/IHE.MHD.List
- http://nictiz.nl/fhir/StructureDefinition/IHE.MHD.DocumentManifest
- http://nictiz.nl/fhir/StructureDefinition/IHE.MHD.Minimal.DocumentReference)
4.4 List of StructureDefinitions
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MedMij uses the FHIR Packaging mechanism. This conveniently bundles all profiles, terminology, example material and other conformance resources you need into a single archive, which can be downloaded or installed using the appropriate FHIR tooling. This version of the information standard uses the following packages:
Note: packages use Semantic Versioning. Other versions can be used at will as long as they have the same major.minor number or a minor number higher than the stated version. |
| HCIM NL / Concept | HCIM EN / Concept | FHIR Resource | URL profile |
| Patient | Patient | Patient | http://fhir.nl/fhir/StructureDefinition/nl-core-patient |
| Zorgverlener | HealthProfessional | Practitioner | http://fhir.nl/fhir/StructureDefinition/nl-core-practitioner |
| PractitionerRole | http://fhir.nl/fhir/StructureDefinition/nl-core-practitionerrole | ||
| Zorgaanbieder | HealthcareProvider | Organization | http://fhir.nl/fhir/StructureDefinition/nl-core-organization |
| Beeld | Image | Media | http://nictiz.nl/fhir/StructureDefinition/images-Media |
| CollectieBeelden | CollectionImages | List | http://nictiz.nl/fhir/StructureDefinition/images-List |
5 Release notes
Release notes can be found on the functional design page.