Keeping up with DICOM

1. Keeping up with DICOM Kevin O’Donnell Toshiba Medical Systems

2. DICOM is not Static • DICOM first published in 1993 • Extended regularly to meet theexpanding needs of Medical Imaging: • Multi-slice CT • 3D Ultrasound • Web-based PACS • USB Memory Sticks • Clinical Measurements • Radiation Dose Reporting • Image Registration & Segmentation • Computer Aided Detection/Diagnosis • and many, Many More . . .

3. DICOM Supplements

4. DICOM Working Groups • WG-1 – Cardiac/Vascular • WG-2 – X-Ray & Angio • WG-3 – Nuclear Medicine • WG-4 – Compression • WG-5 – Exchange Media • WG-6 – Base Standard • WG-7 – Radiotherapy • WG-8 – Structured Report • WG-9 – Ophthalmology • WG-10 – Strategic Advisory • WG-11 – Display • WG-12 – Ultrasound • WG-13 – Visible Light • WG-14 – Security • WG-15 – Mammo & CAD • WG-16 – MR • WG-17 – 3D • WG-18 – Clinical Trials • WG-19 – Dermatology • WG-20 – Integration (HL7) • WG-21 – CT • WG-22 – Dentistry • WG-23 – App. Hosting • WG-24 – Surgery • WG-25 – Veterinary • WG-26 – Pathology

5. DICOM Change Process • Supplements for major changes • Extend Standard by adding new object types, new services, etc. (i.e. New SOP Classes) • About 10 / year • Developed by Working Groups • Require Work Item approved by DICOM Standards Committee • Change Proposals for minor corrections • About 100 / year • Anybody can submit • Backward Compatibility: Avoid changes that break existing implementations • Vendors responsible for monitoring final text change proposals • Consolidated edition published every year • Most recently, January 2008 • Available free at DICOM web site

6. DICOM Change Process Development of a Supplement : • Work Item Proposal • Reviewed / Approved by DICOM Standards Committee • Working Drafts • Developed by Working Groups • Public Comment • Reviewed / Approved by DICOM WG-6 • Published for 45-day Comment Period • Letter Ballot • Reviewed / Approved by DICOM WG-6 • Voted on by DICOM Members • Final Text / Standard • Finalized by DICOM WG-6 • Effective immediately; Incorporated during next publication • …typically a 1-2 year process

7. Maintaining Compatibility Extension vs. Versioning • DICOM is a family of SOP Classes • It’s just “DICOM”; Not DICOM 3.0, 3.1, etc. • Conformance is to SOP Classes, not to a ‘version’ of the Standard • New SOP Classes are added; Old SOP Classes don’t change • Most applications continue to support older SOP Classes when supporting new ones • Association Negotiation • Software can determine if two systems are compatible • Happens each time two DICOM systems open an association (connection) • They negotiate which SOP Classes will be used, and how (e.g. Transfer Syntax) • Based on what each system supports and/or prefers • DICOM Conformance Statement (DCS): • Humans can determine if two systems are compatible • When purchasing, compare the new system to your currently installed systems “This product supports this list of SOP Classes; here are some details about how the SOP Classes have been implemented and how the system behaves when it uses them”

8. Some Recent Additions to DICOM

9. Enhanced Objects • “2nd Generation” objects for most modalities • Common approach to Multi-frame, multi-dimension objects • New Attributes (Private->Public) • Acquisition details, Clinical details • New SOPs for CT, MR, XA/XRF, 3D-XR, PET, OCT, 3D-US • Benefits • Convenient handling of 1000+ slice studies • Faster transfers (orders of magnitude) • Advanced structure for faster, advanced display • Support for modern/advanced protocols • e.g. in CT/MR: cardiac, gating, perfusion, diffusion, angio, fluoro, multi-stack spine, spectroscopy, functional imaging, color, raw data, …

10. Fixed Header Dimension data Pixel data Per-frame header Multiframe Architecture UsingSingle FrameObjects N Objects, N Headers UsingMulti-FrameObjects N Frames, One Header

11. Unified Procedure Step (UPS) Addresses more advanced Workflow needs: • Adds “Push Workflow” & “Create Workitem” • Request another system to add item to worklist • Simplifies Implementation • General Purpose Worklist had N:M relation of SPS:PPS • State diagram was very complex • Unified PS contains details of both requested task & performed task • Adds “Cancel Request” • Lets systems request (and monitor) cancellation of a task • Improves Status/Result Monitoring • Getting PPS was awkward; required configuration and forwarding • 4 SOP Classes operating on 1 IOD • UPS Push, UPS Pull, UPS Watch, UPS Event

12. Unified Procedure Step (UPS) Other Interesting Features: • Allows Push, Pull, and Watch Workflows • Subscription-based Monitoring • Task Locking by performer • Deletion Locking by watchers • Allows Sub-contracting Likely Applications • Radiotherapy • Sup. 74 (Radiotherapy Worklists) is based on UPS • Automates worklists, verification steps, and beam delivery instructions • Now in Trial Implementation with IHE-RO • Softcopy Display Management • Sup. 124 plans to use UPS push workflow and monitoring features • Not intended to obsolete Modality Worklist • MWL has large install base and works well for most situations

13. Registration • New SOP Classes • Rigid Registration Storage • Deformable Registration Storage • Records one or both of: • Transformations to map one or more data sets(e.g. images) into the space of another data set • Fiducials used for the registration • Example use: • Modality or workstation spatially registers two datasets • Registration object is stored to the PACS • Display station retrieves and applies the transformation;displays fused images

14. Segmentation • New SOP Classes • Segmentation Image Storage • Based on Pixels / Voxels • Binary (1-bit/pixel) or fractional(probability or occupancy) • Surface Segmentation Storage • Based on 3D Mesh • May record multiple segments representing: • Tissue type, organ surface, etc. • Example use: • Workstation analyzes images; segments tumor • Segmentation object is stored to the PACS • Display station retrieves/displays segmentation;perhaps for surgical planning

15. Dose Reporting • New SOP Class • X-Ray Radiation Dose SR Storage • Templates for Projection X-Ray, Mammo & CT • Records individual Irradiation Events • Does not depend on creation of digital images • Can be correlated with images for dose mapping • Driven by work of IEC and Euratom • IHE now working to facilitate deployment • Example Use: • Modality stores Dose Reports to PACS • Dose Monitoring system retrieves reports and generates weeklyanalysis of departmental dose; monitors compliance with policies

16. How can you keep up? dicom.nema.org • Download the current issue of the Standard (free) • Both PDF and Word • Both normal and “Diff” version (showing changes from previous issue) • Monitor and Implement CPs (Change Items) • Keep your product current • Review New Supplements • Current documents are visible at all stages of the process • http://www.dclunie.com/dicom-status/status.html • Review the DICOM Strategy Document • Activity reports from all Working Groups • Attend the next DICOM International Conference and Seminar • Stay tuned!

17. How can you contribute! • Ask questions/discuss on the DICOM Newsgroup • http://groups.google.com/group/comp.protocols.dicom • Submit Change Proposals • if you find a gap, error, inconsistency or confusing text • mailto:hclark@medicalimaging.org • Respond to Supplements released for Public Comment • Feedback is particularly welcome during Public Comment period • http://www.dclunie.com/dicom-status/status.html • Join DICOM • Membership categories for users, vendors and national bodies • mailto:hclark@medicalimaging.org • Participate in the DICOM Standards Committee and Working Groups • Submit new Work Item proposals • Help develop new Supplements