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 January 2015 is available here:
This Supplement delivers explanatory information on the usage of DICOM attributes for X-Ray 3D Angiographic Image IOD:
Detailed additional information like scenarios, examples and drawings beyond the definitions in PS 3.3;
Identify scenarios where the X-Ray 3D Angiographic Image is applied;
Indicate restrictions on the applicable scenarios; encourage the usage of Type 3 attributes under particular scenarios;
Assess the applicability for some conditional attributes under particular scenarios;
All use cases where walked through with respect to getting an aligned use of stack id. The essence of the discussion was: The stack id stays the same for all frames as long as the volume is the same, even as the cardiac phase changes.
The supplement was voted to go into final text.
This supplement introduces the Planar MPR Volumetric Presentation State object to the standard.
The goal is to be able to present the same or close to the same volume view on imaging data (XA-3D, MR, CT enhanced objects and others) with a general volumetric presentation state object regardless of computing and displaying system and vendor. The supplement is the first of a series of supplements. The first one focuses on MPR.
Working Group 6 and 11 discussed standalone segmentation use cases. Members of the Working Group 6 argued that segmentation should not be excluded as a SOP class. During a segmentation of a tumor, it is helpful to see the representation in different planes and the user wants to capture these states as presentation states.
It was agreed to allow segmentation objects to have volume presentation states associated with them without any other image objects.
This Supplement introduces a new mechanism for specifying templates for imaging reports. Such reports are intended to be encoded using the HL7 Clinical Document Architecture Release 2 (CDAr2, or simply CDA) Standard.
The goal of this supplement is to create a new family of imaging reports aligned with HL7. Initially there will be templates for radiology reports, aligned with RSNA RadLex and Reporting Initiative. Primarily the reports will be narrative with some discrete data. The reports are planned to evolve to containing more and more discrete data: Diagnostic and screening; evolving to interventional, cardiac, anatomic path and further.
This Supplement defines the CDA format structures and technical constraints, i.e., templates, for documents, sections, and entries to be used in imaging report instances. These report instance templates are thus a set of conformance criteria for such report instances.
The comments from the Public Comment phase were discussed and the document was updated accordingly.
The section on of "Relationship with consolidated CDA" was scrutinized in detail.
Expanding the scope in section 3.20 of the DICOM standard is the main reason for a complete replacement.
Two different approaches were weighted against each other. One would be to to retire Annex A and B and to add Annex C. Another would be to retire the entire 3.20 and add a new 3.21 section.
The versioning problem of the transformation guide came up as an issue. The guidance was agreed upon: If there are more substantial changes then there will be a new annex added. If there are only small changes they will be incorporated into the already available annex.
The supplement was voted to go out for letter ballot.
This supplement introduces a SOP Class to enable anatomically correct measurements on wide field ophthalmic photography 8-bit and 16 bit images. Vendors have implemented new technology which enables the acquisition of OP images using wide field fundus photography. Since the back of the eye is approximately a concave sphere, taking a very wide field image of it introduces large error in any attempt to measure a lesion in that image (the error is very large when using a single value for the DICOM Pixel Spacing Attribute.). Therefore, DICOM WG 9 (Ophthalmology) has determined that a new Information Object Definition is necessary to adequately represent wide field fundus photography.
The supplement has four specialized IODs. There are 8bit and 16bit image objects, divided into stereographic projection and 3D coordinate objects.
It was debated if there are any real world use cases where 16bit and color are used. Two solution alternatives would be to use two SOP classes or to limit 8bit to color and 16bit to greyscale.
The open issues where all taken care of. The method for calculating 2D to 3D points is not recorded in the standard. Decision was made that this is not needed. No ICC profile module is needed. The working group decided that the corneal vertex is a good origin. There is no need for another origin definition.
A further discussion took place on the definitions of spherical and surface contour projections. Spherical projection has a well-known definition but surface contour was decided to be improved to "based on surface measurements of the retinal contour".
Supplement 173 was voted ready to go out for letter ballot.
This supplement describes two new Transfer Syntaxes to embed MPEG-4 Advanced Video Coding (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) will perform consistent with the ITU-T H.264 HiP@Level4.2. This will enable the storage of video files with a resolution of 1920x1080 at 50Hz/60Hz.
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.
The important point from the public comments was to update the media profile for Blu-ray to include H.264 compression for consistency.
A specific use case was discussed: To use H.264 streaming between ultrasound devices in real time and to a Fluoro XRay system. The response from the meeting was that this can be done without DICOM communication and that a DICOM database is not suitable for real time requirements (RTP/RTSP protocols / containers).
Working Group 6 recommended not adding real time support in the supplement.
A longer discussion took place on stereo encoding.
This Supplement defines storage IODs for storing magnetic resonance diffusion tractography (MR DT) results (tracks and measurements) for healthy and diseased brains.
An MR diffusion acquisition sequence (e.g. EPI, HARDI) collects data reflecting the diffusivity of water and the directionality of its movement.
Based upon a model of diffusion in tissue (e.g. simple tensor, multiple-tensor, etc.) this information can be used by tracking algorithms to estimate the pathways followed by the white matter fiber tracts.
The widespread adoption of MR diffusion measurement in the clinical workflow, particularly diffusion tensor imaging (DTI) and tractography, has opened an entirely new non-invasive window on white matter connectivity of the human brain and spinal cord.
MRI diffusion imaging is able to quantify diffusion of water along certain directions, typically on a spatial grid with a resolution of 2mm.
To calculate diffusion tensors, a base-line MRI without diffusion-weighting and at least six differently weighted diffusion MRIs have to be acquired.
Later refinements to the diffusion model and acquisition method include HARDI, Q-Ball, diffusion spectrum imaging (DSI) and diffusion kurtosis imaging (DKI).
A tracking algorithm produces tracks (i.e. fibers) which are collected into track sets. A track contains the set of x, y and z coordinates of each point making up the track. Depending upon the algorithm and software used, additional quantities like Fractional Anisotropy (FA) values or color etc. may be associated with the data, by track set, track or point, either to facilitate further filtering or for clinical use. Descriptive statistics of quantities like FA may be associated with the data by track set or track.
Examples of tractography applications include:
This supplement enables the RESTful Retrieve service to retrieve rendered instances. This is done by adding query parameters to the request URI. These parameters are similar to those already available in the URI and WS Retrieve services.
A client makes an HTTP request with query parameters specifying how the images shall be rendered and receives a response containing those images as the result.
There was an elaborative discussion on what the use cases and goals are for rendering of restful services.
An important use case discussed was to return one image using URI and being able to apply CT presets within the client application. The goal is to present an image ready to be windowed by the user. It was argued that a reasonable initial windowing value should be applied automatically.
The supplement applies to all modalities in which radiographic, radiopharmaceutical or other imaging agents are introduced into a circulatory system in a controlled fashion (CT, MR, XA, NM, US).
The new SOP Classes are introduced with this supplement to describe administration events, flows, pressure, timings, physio-chemical attributes and pharmacological attributes of the agent administration and also consumables related to the administration.
These SOP classes do not describe radioactivity or dosimetry administered.
A discussion took place regarding what information goes into the different types of the Substance Administration SR. For the types defined, planned and performed the discussion centered on Flow Rate Curve and timing when the information in the report is available.
One important aspect is that the modality cannot store images until it has received this information.
It was proposed to add a section with diagrams to show the interaction between the types of reports.
The scope of this Supplement is on treatment delivery and it introduces the concept of RT Radiations along the RT Radiation Set IOD.
A longer discussion took place on how to match specific attributes within sequences. The proposal would be to add a new attribute to the Selector Attribute Macro. The idea was to set constraints to all or some attributes within a sequence of repeated inner structures, e.g. control points.
A scrutinizing walk trough of the part 16 addendum with focus on the CIDs was performed.
The scope of this supplement is the introduction of new RT Radiation IODs representing treatment delivery devices that had no representation in the First Generation DICOM Radiotherapy model.
The draft Sup 176 was presented. There was a wish expressed to illustrate the geometry for delivery device attributes with some explanatory figures.
This supplement adds a SOP Class for Curved and Straightened MPR Volumetric Presentation State to the DICOM Standard.
The new SOP Class will allow rendering of 3D volumes which may be represented as any of the following structures:
SOP Classes in which a single instance may represent 3D volume datasets, such as XA-3D or many of the Enhanced SOP Classes
SOP Classes which by convention allow a collection of instances within a common Frame of Reference to contain spatially related frames that together comprise a 3D volume dataset. This is commonly done within the CT and MR modalities.
3D data may be used in a variety of ways, including quantification through a variety of volume-based algorithms and presentation through a variety of display algorithms, such as frame-by-frame viewing, multi-planar reformatting slicing, surface and volume rendering.
A longer explanation took place of how curved MPR view construction and its attributes are to be understood. The corresponding figures in the supplement were dwelled upon in detail. The discussion ended in the agreement to show the curved MPR view within a 3D box.
This DICOM supplement specifies web-based protocols, based on HTTP/HTTPS, for transmitting and receiving DICOM resources (e.g., images, medical imaging reports).
It is intended to be used for distribution medical imaging related information. It provides simple mechanisms for creating, retrieving, updating, deleting, and searching for DICOM resources.
Data may be transmitted in native DICOM representations or in "rendered" representations (e.g., JPEG or GIF).
This standard relates only to composite DICOM objects (not to other DICOM objects). Authentication, authorization and auditing security mechanisms are outside the scope of this standard.
A longer discussion took place on how precise media types like jpg or jp2 should be. It was agreed that there has to be a way to inform the reader when there has been an improvement performed in addition to the re-documentation.
It was advised to improve on the user goal overview.
This Supplement adds a new extensible IOD 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, yet this conflict with the requirement to be able to render all content.
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 supplement was voted to go out for public comments.