March 2015 Bjoern.Nolte@siemens.com

Here are the summary notes from the latest DICOM Working Group 6 Meeting (WG-06).

WG-06 meets 5 times a year to do technical review and harmonization of the output from the 30 DICOM Working Groups.

Current progress on new DICOM supplements (new chapters to The Standard) is shown below. Also change proposals (bug fixes in The Standard) are shown grouped into voting packages (CPacks).

The current edition of the DICOM Standard, incorporating all Final Text supplements and CPs up to March 2015 is available here:

DICOM Current »

Templates for Procedure Reports in CDA

Sup 155 Final Text in March 2015

This part of the DICOM Standard specifies templates for the encoding of imaging reports using the HL7 Clinical Document Architecture Release 2 (CDA R2, or simply CDA) Standard. Within this scope are clinical procedure reports for specialties that use imaging for screening, diagnostic, or therapeutic purposes.

This Part constitutes an implementation guide for CDA, and is harmonized with the approach to standardized templates for CDA implementation guides developed by HL7. It also provides Business Names for data elements that link data in user terminology, e.g., collected by a report authoring application, to specific CDA encoded elements.

A walk through of the changes done after the letter ballot was presented.

Noteworthy were the following changes:

As an implementation guide for imaging reports, particular attention is given to the use and reference of data collected in imaging procedures as explicit evidence within reports. This data includes images, waveforms, measurements, annotations, and other analytic results managed as DICOM SOP Instances. Specifically, this Part includes a specification for transformation into CDA documents of DICOM Structured Report instances that represent imaging reports.

Serialization must be in accordance with the HL7 CDA hierarchical serialization.

The supplement was voted to go into the standard as final text.

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Ophthalmic Photography

Sup 173 Final Text in March 2015

Ophthalmic photographic imaging devices have been generating DICOM OP images (using a narrow field) for many years. New technology enables devices to generate OP images using a wide field. But since the back of the eye is approximately a concave sphere, it introduces large errors when making anatomic measurements (such as a lesion in the eye). This supplement specifies two new SOP Classes that solve this problem as they enable anatomically correct measurements on wide field ophthalmic photography images.

The author of the supplement presented all changes from the letter ballot replies and their impact in the document.

Among other changes projection was changed to transformation. Common modules such as "Common Instance Reference", "Frame Extraction" and "Enhanced General Equipment" were added.

The supplement was voted to go into final text and thereby become part of the standard.

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Planar MPR

Sup 156 Final Text in March 2015

This supplement adds an IOD and two SOP Classes for a Planar MPR Volumetric Presentation State to the DICOM Standard.

The new SOP Classes allow rendering of 3D volumes or temporal sequences of 3D volumes, which may be represented as any of the following structures:

SOP Classes in which a single instance may represent 3D or 4D volume datasets, such as XA-3D or many of the Enhanced SOP Classes.

SOP Classes that by convention allow a collection of instances within a common Frame of Reference to contain spatially and temporally related frames, which together comprise a 3D or 4D volume dataset. This is commonly the case with CT and MR.

3D and 4D data may be presented through a variety of display algorithms, such as frame-by-frame viewing, multi-planar reconstruction, surface rendering and volume rendering. When a volume presentation is created through the use of a Display Algorithm, it typically requires a set of Display Parameters that determine the specific presentation to be obtained from the volume data. Persistent storage of the Display Parameters used by a Display Algorithm to obtain a presentation from a set of volume-related data is called a Volumetric Presentation State (VPS).

The support of Monochrome, pseudo-color versus true color was debated. Further the discussion concluded that most applications today only handle one modality for Planar MPR presentation states.

Monochrome and true color will be mutually exclusive in the SOP class.

After a brief discussion it was decided to move the very long scope and field section to an informative annex in DICOM part 17.

A line by line review was performed.

Alignment for bounding box cropping came up for discussion. After some clarification, it was decided to align with the encoded volume coordinate system. This means that two opposite points are used to define the cropping volume by the nearest and most far away 3D points.

The tag "Volumetric curve points" was changed to Other Float (OF) 32bit to simplify the handling of points.

The review will continue in the next DICOM Working Group 6 meeting.

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MPEG-4 Transfer Syntax

Sup 180 Revisit planned for June 2015
Sent out for Letter Ballot

This supplement describes three new Transfer Syntaxes to embed MPEG-4 Advanced Video Coding 49 (AVC) / H.264 High Profile / Level 4.2 (HiP@Level4.2) and H.264 Stereo High Profile /Level 4.2 encoded pixel data in DICOM. It does not introduce any new SOP Classes or IODs.

Transfer Syntax MPEG-4 AVC/H.264 High Profile / Level 4.2 (HiP@Level4.2) for 2D Video will perform consistent with the ITU-T H.264 HiP@Level4.2 specifications except that the use of frame packing formats for 3D video is not allowed. This will enable the storage of video files with a resolution of 1920x1080 at 50Hz/60Hz.

Transfer Syntax MPEG-4 AVC/H.264 High Profile / Level 4.2 (HiP@Level4.2) for 3D Video will perform consistent with the ITU-T H.264 HiP@Level4.2 specifications. It should be used for transmitting stereoscopic 3D content with frame packing formats. This will enable the storage of 3D video files with a resolution of 1920x1080 at 50Hz/60Hz in frame packing format. Transfer Syntax MPEG-4 AVC/H.264 Stereo High Profile /Level 4.2 will perform consistent with the ITU-T H.264 Stereo High Profile at Level 4.2. This will enable the storage of video files where higher compression can be achieved due to inter-view prediction. An example of the use would be in binocular operational microscopy.

Support is required in DICOM for 2D and 3D video at 1080P 50/60 Hz as defined by MPEG-4 AVC / H.264 Level 4.2. Considerable space savings can be achieved when storing stereo recordings in Stereo High Profile format. These three new options of transfer syntax will help to support advance technologies with an updated set of higher resolution, frame rates and compression capabilities.

The supplement was voted to go out for letter ballot comments.

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Ext SR Storage SOP

Sup 186 Revisit planned for June 2015
Sent out for Letter Ballot voting

This Supplement adds a new extensible IOD and SOP Class that allows new Content Item types to be used as they are added to the standard.

There is an increasing need for new Content Item types (such as SCOORD3D) and these are being added as needed to application- specific IODs and SOP Classes (such as the Colon CAD Supplement 126). There is a need for a generic IOD and SOP Class to allow new applications to make use of these in a general way. This conflicts with the requirement to be able to render all content. It is also possible that new Relationship Types will be added, and the IOD also addresses these. A specific conformance requirement is specified, that the user be warned in there is content of a type that the rendering software does not recognize or understand. This is consistent with the approach used in other extensible formats like PDF, in which software tools like Acrobat Reader warn about unrecognized content when faced with newer versions.

The description of the behavior as SCU and SCP was improved.

The supplement was voted to go out for Letter Ballot comments.

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Protocol Storage (CT)

Sup 121 Revisit planned for June 2015
Sent out for Letter Ballot voting

The document has been reviewed by members of affiliated organizations (AAPM, RSNA).

The supplement is now focused to two types of protocols. The available protocols on the scanners (defined protocols) and those which were actual used (performed protocols). It was decided to remove/defer a third type (planned protocols) until the process for protocolling individual patients is clearer.

A private tag dictionary is introduced in the supplement to permit descriptions of unique tags for encoding the inevitable model-specific details. Vendors will be encouraged, but not required, to use this to document private attributes.

Discussions included how protocol managers can track the frequency and most recent use of various protocols. It is proposed to derive this information from the performed protocol objects.

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Restful rendering

Sup 174 Revisit planned for June 2015
Sent out for public comments

Poll results for features to be available in this supplement were presented. The most voted for topics were:

  • Implementation and best practices doc
  • PNG transfer syntax (for IHE Rad WIC)
  • Improve MHD-I support
  • Modality Worklist support for UPS-RS
  • Review and update media types
  • STOW append new series or instances
User goals for rendering were presented:

  • Display rendered frame(s) from all -ologies except Whole Slide Imaging
  • Display a single rendered image frame
  • Display a scrolling or tiled series of image frames for cross-sectional modalities
  • Display a cine containing angio, fluro, multi-frame ultrasound images
  • Display a projection xray image with curvy windowing
  • Display key images
  • Display fused images (e.g. CT/PET)
  • Display measurements from operator or physician
  • Replicate the appearance of an image encoded as a presentation state (including annotations)
User goals regarding control were presented:

  • Control Zoom and Pan
  • Control Synchronized scroll
  • Control Synchronized zoom and pan
  • Control scroll through a series in a sensible order
  • Control scroll through a series in a user specified order (space, time, instance number, cardiac phase)
A walk through of the discussion results in the last meeting was presented.

The supplement was voted ready to go out for public comment.

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C-Arm RT Treatment

Sup 175 Revisit planned for June 2015
Sent out for public comments

The structure within the RT Plan was discussed. An RT Plan contains a beam sequence containing beams. Each beam contains BLDs. A BLD is Beam Limiting Device.

To document and control the position of the treatment equipment, the DICOM frame of reference and the IEC 612017 concepts were discussed in depth.

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Web services re-doc

Sup 183 Revisit planned for June 2015
Stays in the draft state

During a walk through of the supplement, a detailed look at status details and codes was performed.

A discussion took place on which rendered media types should be required. Especially if there should be any required video formats. The conclusion was to stay with recommended but not to introduce any other required video formats.

It was elaborated on the format and completeness of the supplement. This re-documentation shall not break current implementations. This supplement will be a replacement for the existing part 18.

A longer debate took place on transfer syntax by accept header versus transfer syntax by parameter. It was decided to postpone the decision by creating an appropriate change proposal, which will go out for broad comments. The change proposal will cover mime type, character sets and transfer syntax.

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Brachytherapy Delivery Instructions

Sup 184 Revisit planned for June 2015
Stays in the draft state

The modifications introduced by this supplement describe worklist support for the brachytherapy treatment management and treatment delivery systems. Intention is to offer similar level of support for brachytherapy treatment workflow as was introduced for the external beam radiotherapy in "Supplement 74: Utilization of worklist in Radiotherapy Treatment Delivery".

This is achieved by the addition of the following:

RT Brachy Delivery Instruction Storage Composite IOD, which contains the data necessary to instruct a treatment delivery device on what is to be delivered. The key element of the IOD is the RT Brachy Delivery Instruction Module, which contains information on the RT Plan to be used, the channels within the plan that will actually be delivered or omitted.

This supplement is being driven by the desire to address the lack of support for brachytherapy treatment delivery workflow in the current standard.

The treatment sequence - the repeating scheme - within the brachytherapy was discussed in detail.

A complete treatment over a longer time, usually weeks, is made up of many fractions, treatment days. Within each of these days a plan is executed. The plan consists of a set of applications. Each application can be delivered in a specific mode, called a pulse.

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Object Evaluation Results IOD

Sup 185 Revisit planned for June 2015
Stays in the draft state

This Supplement specifies the IOD representing object evaluation findings against reference information. It stems from the development of the Quality Assurance with Plan Veto profile in IHE-RO. While the profile originated from use cases to evaluate RT Plan, the IOD is generalized to allow for reporting of evaluation results involving any DICOM object.

Content comes from the change proposal 1288 which introduces a SOP class. The creation of a new supplement is standard when a new SOP class is introduced to the standard.

The evaluation report is introduced to convey problems to a user / operator. An independent system evaluates a treatment plan prior to a therapy with radiation and reports found problems.

The payload in this SOP class is a module called "object evaluation results".

It was advised to keep the same model as in the "Key object selection" structure.

Among the use cases covered is "Pretreatment dose check".

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Small Animal Imaging SOP

Sup 187 Revisit planned for June 2015
Stays in the draft state

The purpose of this supplement is to extend the DICOM standard to also cover the aspects for pre clinical imaging acquisition with small animals. As far as possible the standard mechanisms of DICOM are reused.

A walk through of the document, in pre first read state, was done. The meaning of important concepts and codes together with the information model were presented.

The National Cancer Institute is sponsoring this work.

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CPack 80

WG-06 approved Final Text in March 2015

CPack 81

Current candidates for final text in June 2015

CPack 82 candidates

Current candidates for final text in September 2015
Clicking on one specific Change Proposal above will take to that actual content.

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