3 STATE OF THE ART
3.1 Dose Summary on FHIR
An ongoing work item within the DICOM
R
WG-
20 and the HL7
R
O&O (Orders and Observations)
group analyses the specification and the profiling of
the Dose Summary on FHIR
R
(DICOM, 2020a). The
aim of this working item is to describe the minimal re-
quired dose information within a normative resource
(likely the Observation resource), allowing commu-
nication of the accumulated dose information from
the performed procedure step, to provide a summary
overview of the patient dose exposure. This working
item will involve several activities, like the identifica-
tion of the minimal dose information from various na-
tional regulations and recommendations, and the pro-
filing of the Observation resource in order to integrate
the minimal dose information. The scope of the Dose
Summary on FHIR
R
is to share a summary of dose in-
formation by exam through FHIR
R
, which is different
than the scope of this analysis: sharing details of the
radiation administration, and sharing of the enhanced
data like SSDE and effective dose to third party appli-
cations.
3.2 DICOM SR to FHIR Mapping
Another ongoing work item is a mapping be-
tween DICOM
R
SR and FHIR
R
resources (DICOM,
2020b). The scope of this work item is to map key
SR templates and content into FHIR
R
resources. At
the time of this paper, the work item was concentrated
in the mapping of measurement TIDs (Template IDs:
TID1410, TID1411, and TID1420). There are two
explored solutions: Observation based solution, and a
CDA
R
based solution. The first solution is describing
all elements inside the TIDs using the ”hasMember”
and ”component” attributes. The second solution is
to translate the SR into CDA
R
, following DICOM
R
PS3.20 (DICOM, 2020d). After CDA
R
mapping, a
translation between CDA
R
and FHIR
R
can be per-
formed using custom resources, following the project
Clinical Document Architecture V2.1 (HL7, 2020a).
The methodology is very interesting, as it allows the
direct mapping from SR templates to custom FHIR
R
resources. However, this is less relevant for DICOM
R
Radiation SR templates. In fact, in PS3.20, there is
only one CDA
R
section defined, summarizing the pa-
tient dose exposure. This section is useful for the
Dose Summary on FHIR
R
work item; however, it is
not useful for a detailed mapping between DICOM
R
RDSRs and FHIR
R
resources.
3.3 DICOM SR and FHIR
Representations for Imaging
Measurements
An analysis was performed within the 30th Project
Week event, in order to convert the TID 1500 - Mea-
surement Report, to FHIR
R
resources (H. Meine,
2019). The working team concluded that the FHIR
R
resources should be used to store only the most rele-
vant information, and to keep DICOM
R
as main stor-
age format. A python based project is shared in a
GitHub repository to describe the different samples
and code used to generate the FHIR
R
resources. From
the samples provided, the targeted mapping between
TID 1500 and FHIR
R
is based on combination be-
tween the resources DiagnosticReport, Observation
and ImagingStudy.
4 METHODOLOGY
4.1 Apization of DICOM Radiation SR
The best way to expose detailed radiation informa-
tion through an API is to combine the strength of
FHIR
R
(HL7, 2019) (T. Benson, 2016), and the sta-
ble structure of the RDSRs coming from PS3.16
(DICOM, 2020c). HL7
R
FHIR
R
provides a strong
API model and capabilities for searching and ex-
posing resources, like indexing and searching oper-
ations. The FHIR
R
community has published nu-
merous open source tools, simplifying any integration
with a FHIR
R
server, and simplifying the creation
of FHIR
R
servers. FHIR
R
also comes with defined
primitive and complex types, ready for use. Compar-
ing to proprietary APIs, FHIR
R
facilitates conception
of custom resources and the profiling of existing re-
sources, which reduces the time to production. In
fact, many open source applications exist, facilitat-
ing the profiling of FHIR
R
resources. Examples in-
clude FHIR
R
Shorthand / Sushi (HL7, 2020b), SIM-
PLIFIER.NET (K. Gopinathan, 2018), and FHIR
R
IG
publisher tool (HL7, 2020d). For custom resources,
HL7
R
provides FHIR
R
spreadsheet authoring, an Ex-
cel or OpenOffice structure for designing FHIR
R
data
types, resources, and profiles (HL7, 2020c).
DICOM
R
PS3.16 provides a complete definition
of each RDSR type, with a clear definition of con-
tent items, cardinality, data type, format, and con-
straints. The structure of the RDSRs have been de-
fined since 2004 and tested hundreds of times during
testing events like IHE Connectathons, or directly in
production. Their structure has evolved over the years
Custom FHIR Resources Definition of Detailed Radiation Information for Dose Management Systems
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