Lessons Learned from the DICOM Standardization Effort Lessons Learned from the DICOM Standardization Effort
- 1. Lessons Learned from the DICOM Standardization Effort David Clunie, Chairman DICOM Standards Committee Harry Solomon, Chairman DICOM Working Group 1 (Cardiovascular Information)
- 2. What is DICOM? The pre-eminent international standard for communication of medical digital images and related information The product of 18 years of industry / clinical collaboration, beginning as ACR-NEMA 16 Parts, over 1500 pages A standard that works! Hundreds of products, thousands of devices
- 3. About Standards Development It’s not easy or cheap Intellectual capital, especially in information modelling Consensus building among all stakeholders DICOM - $10’s of millions, thousands of committee hours
- 4. Organizational Aspects Initial standard development is only a fraction of the total effort On-going demand for interpretation, maintenance, evolution, education Needs a solid organizational infrastructure, focused on the standard itself, for the long term DICOM Standards Committee utilizes the National Electrical Manufacturers Association as Secretariat Major support from RSNA and HIMSS “Integrating the Healthcare Enterprise” initiative
- 5. DICOM Standards Committee 25 manufacturers, plus 2 manufacturers’ organizations (NEMA - US, JIRA - Japan) 15 clinical user organizations (worldwide) radiology, cardiology, pathology, dentistry, opthamology, dermatology, gastro-enterology FDA Center for Devices and Radiological Health National Cancer Institute Canadian Institute for Health
- 6. Features of DICOM as a Medical Data Interchange Standard
- 7. Encoding Tagged, variable length data elements Tagging conceptually similar to XML (but tags are 32-bit binary, not variable length ASCII) Similar to TIFF Supports binary data values Encapsulated JPEG encoded pixel data Supports hierarchical data organization Extensible with private data elements
- 8. Object Orientation Fundamental unit of interchange is an information object Instance Each Instance has a globally Unique ID Registered under the rules of ISO 9834-3 Information object classes defined for each clinical data acquisition modality (CT, MR, etc.)
- 9. Data Sets Sets of object Instances are organized by patient, study, and series virtual hierarchical folders Object Instances carry their full contextual identification (patient, order, study, procedure step, series) pargmatically more effective than separate objects managing each context level
- 10. Network Services Network Object Instance transfer Departmental workflow management (orders, status) Robust object management Object storage Query and Retrieve Media-based Object Instance file transfer CD-R, DVD, MOD DICOM MIME type for email attachment
- 11. Privacy and Security DICOM network communications may use SSL/TLS for node identification and/or transport encryption DICOM files (on media-based interchange) may use CMS (RFC-2630) crypto wrapper Object de-identification profile now in ballot allows scrubbed identifiers to be encrypted within the object
- 12. Clinical Trials DICOM WG18 (Clinical Trials) currently developing header and profile for DICOM objects submitted for clinical trials WG18 Secretariat is National Cancer Institute
- 13. Structured Reporting Much of recent DICOM effort directed to structured documentation of analyses and measurements SR uses a hierarchical tree of structured content items, using DICOM object syntax Unambiguous documentation of meaning through text, categorical codes, numeric measurements, inter-item relationships Careful attention to clinical observation context Leverage use of external coded vocabularies / terminologies Robust references to spatial and temporal coordinates in DICOM object Instances Explicit chain of inference may be documented
- 14. SR Use Cases Radiology / Cardiology / Pathology reports Computer Aided Detection / Diagnosis Key Image Notes SR Object Instances are separate from the analyzed Object Instances A single SR may report across multiple referenced objects from multiple studies
- 16. History Cardiology community engaged with DICOM since 1992 for information standardization in the catheterization lab X-ray Angiographic images Invasive hemodynamic and electrophysiological waveforms Waveform digital samples, not picture of a display Non-invasive waveforms (ECGs) a “free” subset Associated measurement reports
- 17. Waveform Object Definition Channel Definition harmonized with HL7 v.2.3 Channel Source may use SCP-ECG lead codes Equipment creates Standard DICOM Composite Object Model
- 18. Annotation Annotations part of the data acquisition may be included in the Waveform Object Instance e.g., suppressed pacemaker spikes Other annotations may be included in a Structured Report Object Instance global or per-lead measurements interpretive statements Both methods allow full description of annotated region (temporal coordinates) by sample number, by time offset, or by absolute time Annotations may be free text, or coded terms
- 19. Implementations DICOM Waveform objects are being used for cath lab invasive waveforms allows management of Waveform objects with same infrastructure as DICOM angiographic images Commercial software available provides transcoding of proprietary format waveforms to DICOM format Many public and commercial toolkits available for DICOM object formatting and communication