PS-2020a / part17

RRR Measurement Report SR Document for​ Planar and Volumetric ROI (Informative)​

This Annex contains examples of the use of ROI templates within Measurement Report SR Documents.​

RRR.1 Measurement Report SR Document Volumetric ROI on CT Example​

ThisCTexampledescribestheminimumcontentnecessarytoencodeasinglemeasurement(volume)madefromasinglevolumetric​ ROI encoded as a single segment that spans two source CT images.​

Note​

1.​References to Segmentation Image or Surface Segmentation objects are encoded as IMAGE references, with a single​ value specified in Referenced Segment Number.​

2.​The method of volume calculation is not described in this example.​

Table RRR.1-1. Volumetric ROI on CT Example​

RRR.2 Measurement Report SR Document Volumetric ROI on CT Example​

ThisCTexampledescribesasetofmeasurements(volume.longaxisandmeanattenuationcoefficient)madefromasinglevolumetric​ ROI encoded as a single segment that spans two source CT images, and includes a description of the measurement methods and​ the finding site, as well as an image library to describe characteristics of the images used, and categorical observations at the​ measurement group and entire subject level.​

Note​

1.​For a different modality than CT, the choice of measurement for the mean intensity would not be (122713, DCM, "Atten-​ uation Coefficient").​

2.​For MR one might use (110852, DCM, "MR signal intensity"), or (110804, DCM, "T1 Weighted MR Signal Intensity"),​ etc. See also CID 7180 “Abstract Multi-dimensional Image Model Component Semantics” for various appropriate signal​ intensity types for MR and other modalities.​

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3.​For PET one might use (110821, DCM, "Nuclear Medicine Tomographic Activity"), in which case the specific type of​ signal would be apparent from the units, e.g., ({SUVbw}g/ml, UCUM, "Standardized Uptake Value body weight") or for​ activity-concentration, (Bq/ml, UCUM, "Becquerels/milliliter"). See also CID 84 “PET Units”.​

4.​Care should be taken when selecting modifiers such as (370129005, SCT, "Measurement Method") versus (121401,​ DCM, "Derivation").​

5.​The finding site and laterality within the measurement template (TID 1419 “ROI Measurements”) are factored out and​ shared by both measurements.​

6.​ThepatternusedfortheimagelibraryusesTID4020“CADImageLibraryEntry”,thoughcommonalitymayberefactored.​

7.​The length of the long axis of the volumetric ROI is encoded, but the end points of the line segment used to make that​ measurement are not recorded, since only the volumetric spatial description of TID 1411 is used. For an alternative​ encoding, see Section RRR.5.​

Table RRR.2-1. Volumetric ROI on CT Example​

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RRR.3MeasurementReportSRDocumentPlanarROIonDCE-MRTracerKinetic​

Model Example​

This DCE-MR example illustrates encoding measurements of mean and standard deviation Ktrans values in a planar ROI.​

Note​

1.​The measurement method and finding site and laterality within the measurement template (TID 1419) are factored out​ and shared by both measurements.​

Table RRR.3-1. Planar ROI on DCE-MR Example​

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RRR.4MeasurementReportSRDocumentVolumetricandSUVROIonFDGPET​

Example​

This FDG PET example illustrates encoding measurements of various SUVbw related measurements.​

Note​

1.​The real world value map reference (for intensity, not size measurements) and finding site within the measurement​ template (TID 1419) are factored out and shared by measurements.​

2.​The time point is described in this case only with a simple label.​

Table RRR.4-1. SUV ROI on FDG PET Example​

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RRR.5 Measurement Report SR Document Volumetric ROI with RECIST Linear​ Distance Specified by Coordinates on CT Example​

ThisCTexampledescribesasetofmeasurements(volume,longaxis(RECIST),shortaxis(WHObi-dimensional)andmeanattenuation​ coefficient) made from a single volumetric ROI encoded as a single segment, including specification of the end points of the line​ segment used to make the linear distance measurements.​

Note​

1.​The lengths of the long axis and the short axis of the lesion are not encoded as characteristics of the volumetric ROI,​ but rather the long axis and the short axis are encoded explicitly as the end points of line segments used to make those​ measurements. The commonality of the Tracking Unique Identifier establishes that they are measurements of the same​ ROI. If multiple measurements were to be made of the same ROI over time or by different observers, other content​ items such as those related to Timepoint, Activity Session and Observer may be used. For an alternative encoding, see​ Section RRR.2.​

2.​The pattern of using multiple sibling linear distance measurements within TID 1419 “ROI Measurements” is similar to​ and not incompatible with the pattern used for length, width and height in the OB/GYN Ultrasound template TID 5016​ “LWH Volume Group”.​

3.​The Finding Site information is duplicated in the second measurement template invocation in this example, though it is​ not required to be.​

Table RRR.5-1. Volumetric ROI on CT Example​

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SSSUseofImageLibrariesinSRDocuments​ (Informative)​

This Annex contains examples of the use of Image Library templates within SR Documents.​

SSS.1 Image Library for PET-CT Example​

This PET-CT example dillustrates an Image Library in which Attributes of images for two modalities are described, with common At-​ tributes factored out of the individual image references.​

Note​

1.​OnlytheAttributesofrelevancetoSUVandspatialmeasurementsareincluded,notacompletedescriptionofallaspects​ of acquisition.​

2.​Only two images for each modality are described, rather than all slices acquired, since it is usually only necessary to​ describe images that are referenced elsewhere in the SR content tree, e.g., on which a region of interest is specified​ from which measurements are made.​

Table SSS.1-1. Image Library for PET-CT Example​

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TTT X-Ray 3D Angiographic Image Encoding​

Examples (Informative)​

TTT.1 General Concepts of X-Ray 3D Angiography​

This chapter describes the general concepts of the X-Ray 3D Angiography: the acquisition of the projection images, the 3D recon-​ struction, and the encoding of the X-Ray 3D Angiographic Image SOP instances. They provide better understanding of the different​ application cases in the rest of this Annex.​

TTT.1.1 Process of Creating An X-Ray 3D Angiography​

Two main steps are involved in the process of creating an X-Ray 3D Angiographic Instance: The acquisition of 2D projections and​ the 3D reconstruction of the volume.​

Figure TTT.1.1-1. Process flow of the X-Ray 3D Angiographic Volume Creation​

TTT.1.1.1 Acquisition of 2D Projections​

The X-Ray equipment acquires 2D projections at different angles. The Acquisition Context describes the technical parameters of a​ set of 2D projection acquisitions that are used to perform a 3D reconstruction. In the scope of the X-Ray 3D Angiographic SOP Class,​ all the projections of an Acquisition Context share common parameter values, such as:​

•​Detector settings, anti-scatter grid, field of view characteristics​

•​Distances from the X-Ray source to the Isocenter and to the detector, table position and table angles​

•​Focal spot, spectral filters​

•​Contrast injection details​

If one value of such common parameters changes during the acquisition of the projections, then more than one Acquisition Context​ will be defined.​

TypicallytheprojectionsofanAcquisitionContextaretheresultofarotationalacquisitionwheretheX-Raypositionerfollowsacircular​ trajectory. However, it is possible to define an Acquisition Context as the set of multiple projections at different X-Ray incidences​ without a particular spatial trajectory.​

An Acquisition Context is characterized by a period of time in which all the projections are acquired. Some other parameters are used​ to describe the Acquisition Context: start and end DateTime, average exposure techniques (mA, kVp, exposure duration, etc.), posi-​ tioner start, end and increment angles.​

Additionally, other technical parameters that change at each projection can be documented in the X-Ray 3D Angiographic SOP Class​ on a per-projection basis:​

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•​kVp, mA, exposure duration​ •​Collimator shape and dimensions​ •​X-Ray positioner angles​

TTT.1.1.2 3D Reconstruction​

The 3D Reconstruction Application performing the 3D Reconstruction can be located in the same X-Ray equipment or in another​ workstation.​

A 3D Reconstruction in the scope of the X-Ray 3D Angiographic SOP Class is the creation of one X-Ray 3D Angiographic volume​ fromasetofprojectionsfromoneormoreAcquisitionContext(s).Therefore,one3DReconstructioninthisscopereferstotheresulting​ volume, and not to the application logic to process the projections. This application logic is out of the scope of this SOP Class, the​ same encoding will result whether several 3D Reconstructions are performed in a single or in multiple application steps to create​ several volumes (e.g., low and high resolution volumes) from the same set of projections.​

One 3D Reconstruction is characterized by some parameters like name, version, manufacturer, description and the type of algorithm​ used to process the projections.​

The 3D Reconstruction can use one or more Acquisition Contexts to generate one single X-Ray 3D Angiographic Volume. Several​ 3D Reconstructions can be encoded in one single X-Ray 3D Angiographic Instance.​

TTT.1.2 X-Ray 3D Angiographic Real World Entities Relationships​

This section describes the relationships between the real world entities involved in X-Ray 3D Angiography.​

The X-Ray equipment creates one or more acquisition contexts (i.e., one or more rotational acquisitions with different technical​ parameters). The projections can be kept internal to the equipment (i.e., not exported outside the equipment) or can be encoded as​ DICOMinstances.InthescopeoftheX-Ray3DAngiographicSOPClass,theprojectionscanbeencodedeitherasX-RayAngiography​ SOP Class or Enhanced XA SOP Class.​

If the projections are encoded as DICOM Instances, they can be referenced in the X-Ray 3D Angiographic image as Contributing​ Sources. Each Acquisition Context refers to all the DICOM instances involved in that context. If the projections are kept internal to​ the equipment, the X-Ray 3D Angiographic image can still describe the technical parameters of each acquisition context without ref-​ erencing any DICOM instance.​

The 3D Reconstruction Application creates one or more 3D Reconstructions, each 3D Reconstruction uses one or more Acquisition​ Contexts. One or more 3D Reconstructions can be encoded in one single X-Ray 3D Angiographic Instance.​

Figure TTT.1.2-1. Relationship between the creation of 2D and 3D Instances​

TTT.1.3 X-Ray 3D Angiographic Pixel Data Characterization​

Similarly to other 3D modalities like CT or MR, the X-Ray 3D Angiographic image is generated from original source data (i.e., original​ projections) which can be kept internal to the equipment. In this sense, the 3D data resulting from the reconstruction of the original​

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