June 2016 Bjoern.Nolte@siemens.com

Here are the summary notes from the most recent DICOM Base Standard Meeting (WG-06).

WG-06 meets five times a year to do technical review and harmonization of the output from the 31 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).

CT Protocol

Sup 121 90% Pre Final Text

The purpose of this extension to the standard is to enable distribute defined CT protocols and to record what was actually performed. The typical query and retrieve behavior is also included.

The SOP Classes address details including:

  • patient preparation & positioning
  • equipment characteristics
  • acquisition technique
  • reconstruction technique
  • preliminary image handling such as filtering, enhancement
  • results data storage (auto-sending)

The SOP Class for definition are typically scanner model and version specific. The performed SOP Class records the patient specific actual values.

The primary goal is to set up the scanner, not to script the entire behavior of the department, or the scan suite. The protocol object supports simple textual instructions relevant to the protocol such as premedication, patient instructions, etc. Formal coding and management of instructions may be handled with other objects and services such as the Contrast Injection SR or the Modality Worklist (MWL).

The supplement also introduces a Private Data Element dictionary to permit description of scanner model characteristics and the ongoing addition of system-specific features and settings. This dictionary allows protocol management systems to display the value with an appropriate label to the operator.

The reference mechanism to raw data is improved.

The supplement is close to Final Text. It is planned to use telephone conferences to get there before the September meeting.

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RT Prescription 2nd gen. RT

Sup 147 80% Close to ready for Trial Use

This supplement addresses the need for a new generation of IODs and processes required for use in Radiotherapy. This supplement is the base for further IODs which together will define the second generation radiotherapy.

The second generation classes aim to:

  • Support legacy and modern equipment
  • Utilize workflow, worklist and procedure step concepts from DICOM
  • Use the enhanced DICOM IODs and advanced concepts including: 3D segmentation, mesh representation, rigid and deformable registrations
  • Explicit separate IODs for different use cases: Tomo-therapeutic, C-Arm, and Robotic beams

The definitions of selected codes from the CIDs are improved.

An advice is introduced that CID SUP147001 contains advice from the prescribing physician regarding the treatment.

It is discussed and agreed that the segmentation annotation module shall be made more precise.

The supplement is close to be ready for Trial Implementation, where valuable feedback is expected.

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Instance Approval

Sup 192 70% Before Letter Ballot

This Supplement defines a storage SOP Class to record and convey approval (or disapproval) of instances. The nature, basis and scope of the approval depends on the semantics of the codes used in the assertion. Specific codes and examples are provided for assertions about CT Protocols stored as DICOM instances.

The assertions are encoded using a macro in this supplement. It was factored out to be used in both CT protocol handling and RT workflows.

Approvals and handling of assertions are discussed: How can different approvers re-approve after an earlier disapproving record? How can level of concern be stated per assertion and linked to different approvers? There is currently no final clear best solution available.

The next milestone for the supplement is Letter Ballot. Telephone conferences are planned to get to Letter Ballot before the September meeting.

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Patient Radiation Dose

Sup 191 60% After Public Comment

This supplement defines the recording of the estimated radiation dose to a patient.

This includes radiation dose from CT, projection X-Ray, and radiopharmaceutical administration (diagnostic). Dose from external beam therapy, ion beam therapy, or brachytherapy is out of scope along with occupational radiation exposures.

A new Structured Report (SR) object template and SOP Class is introduced to record dose information. The SR dose object allows the data flow and data management of patient estimated radiation dose reports to be disentangled from the data flow and data management of images.

To include recording of events is discussed and the level of customization level of what has to be recorded. The proposal from the editor is for the user to choose a model and strictly fill out the corresponding fields.

The model, for example a two cylinder model, used within the RDSR object and the way it is registered to the clinical images is scrutinized in detail e.g. patient orientation, right hand coordinate system. The conclusion is that there must be enough constraints on the patient model to make a useful registration possible.

There is an agreement that a model can reference a series of images not only a single image.

In the informative slide set for this supplement there will be examples showing different possibilities to register between the patient model and the Frame Of Reference (FOR) e.g. Image FOR, fiducial FOR and the simplified case "patient top head".

The next milestone for the supplement is Letter Ballot.

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View overview slides »

RESTful Non-Patient

Sup 194 50% Public Comment requested

This supplement defines Restful Services for retrieving, storing, and searching for non-patient related objects such as hanging protocols, color palettes, procedure protocols, etc.

The transactions defined for this service are very similar to those defined for the the equivalent study/image services. They allow a user agent to retrieve, store, and search for non-patient related objects from an origin server in DICOM Media Types.

Security is beyond the scope of the RESTful services defined in this supplement. However generic Web security mechanisms are fully compatible.

There is a proposal to keep all services together for the instance to mirror the service structure for patient related instances. Further it is decided to change the naming from objects to instances. The reason being that instance is being used more frequently than object in the standard.

It is planned to add a guideline on relational or a tree like query model.

The supplement was approved for public comments. Deadline for comments is August 4.

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View slides presented »

View public comment instructions »

HEVC H.265 Video Coding

Sup 195 50% Public Comment requested

The use of video data in the medical industry has increased and new technologies providing better colors or higher precision are available on the market. Meanwhile, the needs for reduced storage and media exchange cost remains important. To answer the related demand for higher 4:2:0 compression efficiency, this supplement proposes to add the following profiles:

Transfer Syntax HEVC/H.265 Main Profile /Level 5.1 will perform consistent with the ISO/IEC 23008-2:2016 HEVC Main Profile at Level 5.1. This will enable the storage of video files with a resolution of 4096x2160 at 50Hz/60Hz.

Transfer Syntax HEVC/H.265 Main 10 Profile / Level 5.1 will perform consistent with the ISO/IEC 23008-2:2016 HEVC Main 10 Profile at Level 5.1. This will notably enable the storage of video files with a higher dynamic range and a wider gamut space and a resolution of 4096x2160 at 50Hz/60Hz.

HEVC stands for High Efficiency Video Encoding and is a common standard of MPEG and ITU. Please see the following link for details: http://mpeg.chiariglione.org/standards/mpeg-h/high-efficiency-video-coding

HEVC/H.265 has now two associated pools of patents which define royalties to pay for when buying or using HEVC/H.265 codecs.

The supplement was approved for public comments. Deadline for comments is July 22.

View details of 195 »

View presented slides of 195 »

View public comment instructions »

HEVC-H.265 Still Image Video Coding (4:0:0 and 4:4:4)

Additionally a new video compression supplement is presented for still images:

HEVC-H.265 Video Coding (4:0:0 and 4:4:4) In this supplement, it is proposed to include new profiles in order to offer a more efficient way to store and manage lossless still images. This aims at replacing the inconvenient storing of pure raw files in PACS environments. Initial targets are CT images information. Each image is encoded with two independent parts: One lossy and one lossless.

The targeted applications include using HEVC streams to store and exchange lossless images but also the easy production of lossy content out of a stored lossless content. The proposed profiles aim at compressing Monochrome and 4:4:4 images as these are the ones which usually require processing and storage in a lossless format.

Two new Transfer Syntaxes to embed are described:

Transfer Syntax "HEVC/H.265 Scalable Monochrome" will perform consistently with:

  1. the ISO/IEC 23008-2:2016 HEVC Scalable Monochrome Profile at Level 5.1 except for additional constraints on the enhancement layers of the coded bitstreams.
  2. the ISO/IEC 23008-2:2016 HEVC Scalable Monochrome 12 Profile at Level 5.1 except for additional constraints on the enhancement layers of the coded bitstreams
  3. the ISO/IEC 23008-2:2016 HEVC Scalable Monochrome 16 Profile at Level 5.1 except for additional constraints on the enhancement layers of the coded bitstreams.

Transfer Syntax "HEVC/H.265 Scalable Main 4:4:4" will perform consistently with:

  1. the ISO/IEC 23008-2:2016 HEVC Scalable Main 4:4:4 Profile at Level 4.1 except for additional constraints on the enhancement layers of the coded bitstreams.

The lossless compression level for HEVC is comparable to JPG2000 and JPEGLS. At similar bit-rates an average advantage of -6dB is presented together with outliers of -2dB to -20dB for lossy coding.

View details of still image video »

View presented slides of still image video »

Contrast Agent

Sup 164 40% In Work

The purpose of this extension to the standard is to cover the administration of imaging agents.

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).

There are three types of Structured Report objects proposed:

  • Defined - definition of generic administration protocols.
  • Planned - represents patient specific plans to deliver the imaging agent.
  • Performed - reporting the actual administration delivered during a medical imaging study. The operator may program a delivery system with an intended delivery. This program is captured in this object. The actuals may deviate from the programmed plan based on a variety of factors. The actual delivery is captured in this object.

The common modules are refactored.

The current model of having the same information in to structures, a simple tag based and as a structured report encoding, is prone to inconsistencies. It is decided to remove the simple structure altogether. If there are good arguments against this decision they should be conveyed during the public comment. One specific concern is if there is timing issues as parsing of structured report structures is more complex.

Further the separation of radioactive and pharmaceutical into separate objects and to reuse them as necessary is noted as an open issue.

During the planning stage there is no waveform inclusion but during recording waveform information can be added if it is part of the procedure.

The supplement is close to be ready for Public Comments. Telephone conferences are planned to get there before the September meeting.

View details »

Web Services Redoc

Sup 183 40% In Work

This extension to the standard specifies web services for managing and distributing DICOM Information Objects, such as medical images, annotations, reports, etc. It defines services and their APIs using the HTTP family of protocols. It is intended to be used for the distribution of medical imaging studies and related information to healthcare organizations, providers, and patients.

The concept of etags, representing conditional header fields, is discussed. With this concept constructs like if-match, if-non-match and if-range are made available. It is agreed to put the use of this as an open issue.

The next milestone for the supplement is to reach maturity and approval for distribution for Public Comment.

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Ophthalmic Angiography

Sup 197 20% First Read

This Supplement defines Storage SOP Classes to enable "en face angiography" images based upon ophthalmic computed tomography (OCT) technology.

With special image acquisition sequences and post hoc image processing algorithms, en face angiography detects the motion of the blood cells in the vessels to produce images of blood flow in the retina and choroid with capillary-level resolution.

The resultant en face images are similar to images obtained in retinal angiography with contrast dye is administered intravenously, though subtle difference is observed when comparing these two modalities.

This technology enables a high resolution visualization of the retinal and choroidal vascular network to detect the growth of abnormal blood vessels, and to provide additional insights in diagnosing and managing a variety of retinal diseases including diabetic retinopathy, neo vascular age-related macular degeneration, and retinal vein occlusion.

The slide set illustrating the clinical usage is presented.

The current version of the supplement is presented to the base standard group. There is advice from this group to use country neutral codes, which can be converted into the appropriate local language according to the market needs.

The initial overview and concepts are presented.

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View overview slides »

CPack 86

WG-06 approved Final Text in June 2016

CPack 87

Current set for September 2016 Final Text.

CPack 88 candidates

Current candidates for final text in November 2016
Clicking on one specific Change Proposal above will take to that actual content.