DICOM Digital Imaging Communications in Medicine

Communication Protocols: Key to Connectivity nLayered Model, each layer performs a specific function nSet of Services and Protocols nConnectivity requires sharing of a complete protocol nCommunication requires a shared Semantic Context

ISO Reference Model LLC MAC PHYSICAL DATA LINK NETWORK TRANSPORT SESSION PRESENTATION APPLICATION Fiber, Coax, UTP, µWave End-to-End communication Data Formatting, Compression,Encryption File Transfer, , HTTP Ethernet, FDDI, etc. Internetworking Upper Layers (DICOM) Synchronization,Comm. Management Lower Layers

Communication Standards nProtocols are defined by standards nA Standard is an agreement which may be voluntary, Government mandated, or International Law nProtocols may also be proprietary

Who Defines Communication Standards? nUser Consortia (e.g., HL7) nOrganizations (e.g., NEMA, IEEE) nUS Government Agencies (e.g., ANSI, NIST) nForeign Government Agencies (e.g., CEN) nUnited Nations (e.g., ISO, CCITT)

ACR-NEMA n ACR and NEMA form a joint committee n Publication of Version 1.0 n Compression and Mag Tape Standards n Publication of Version 2.0 n Began work on Network Version with HIS/RIS

DICOM nThe name was changed to separate the standard from the originating body n Release of Parts 1 and 8 of DICOM n RSNA demonstration, Part 8 n DICOM Parts 1-9 approved, RSNA demonstration of ALL parts n Part 10: Media Storage and File Format n Parts 11,12, and 13 plus Supplements

The Parts of the DICOM Standard nPart 1 - Introduction and Overview nPart 2 - Conformance nPart 3 - Information Object Definitions nPart 4 - Service Class Definitions nPart 5 - Data Structures & Semantics nPart 6 - Data Element Listing and Typing nPart 7 - Message Exchange Protocol nPart 8 - Network Support for Message Exchange nPart 9 - Point-to-Point Support

The Parts of the DICOM Standard nPart 10 - Media Storage and File Format nPart 11 - Media Storage Application Profiles nPart 12 - Media Formats and Physical Media nPart 13 - Print Management Point-to-Point

DICOM Application Domain MAGN ETOM Information Management System Storage, Query/Retrieve, Study Component Query/Retrieve, Patient & Study Management Query/Retrieve Results Management Print Management Media Exchange LiteBox

Summary of DICOM Features nNETWORK PROTOCOL uDICOM incorporates negotiation to permit nodes to agree on the functions to be performed nMESSAGE ENCODING uDICOM defines 24 data types (V2.0 had 4) uDICOM message encoding includes JPEG compression (17 varients) uDICOM includes encapsulated image and multi-frame syntaxes uDICOM supports multiple character repertoires

Summary of DICOM Features nOBJECT DATA MODEL uDICOM is based on a completely specified data model uDICOM includes a robust UID mechanism nDATA DICTIONARY uDICOM includes a large number of new data elements nSERVICE CLASSES uDICOM defines classes of service for specific applications (e.g. image management, printing) and conformance levels

Summary of DICOM Features nOff-Line Media Support uDICOM defines a directory structure and media profiles nCONFORMANCE uDICOM requires conformance statements and contains detailed conformance requirements

DICOM Terminology nDICOM Message Service Element (DIMSE) - The set of DICOM Application Layer communication services. nDIMSE Service Group (DSG) - A subset of the full DIMSE services which is applicable to a specific IOD. nInformation Object Definition (IOD) - A data abstraction of a class of real-world objects. A collection of related attributes (data elements).

DICOM Terminology nService Class - A set of functionality relating to a single type or real-world activity. Composed of a set of SOP Classes plus rules and associated semantics. nService-Object-Pair Class (SOP) - The atomic unit of DICOM functionality. Composed of an IOD and a DIMSE Service Group plus restrictions or extensions of the IOD. (Equivalent to an Object Class)

Service-Object Pair Class SOP Data Dictionary Real-World Object Information Object DIMSE Service Group

DICOM Service Classes nComposite uVerification uStorage uQuery/Retrieve uStudy Content Notification nNormalized uPatient Management uStudy Management uResults Management uBasic Print Management

Conformance nDICOM Part 2 specifies the structure of a conformance statement nDICOM does not specify a test suite or a compliance verification mechanism nAll DICOM implementations must be supported by a properly constructed conformance statement

DICOM Conformance Statement nImplementation Model which describes the Application Entities in the implementation nDetailed specification of each Application Entity uSOP Classes supported upolicies for initiation and acceptance of associations nPresentation Contexts nSOP options nSupported communications protocols nSpecializations nConfiguration

Purpose of a Conformance Statement nAllow a user to determine which optional components of the DICOM Standard are supported by a particular implementation, and what extensions or specializations an implementation adds. nBy comparing the Conformance Statements from two implementations, a knowledgeable user should be able to determine whether or not interoperability is possible.

DICOM Conformance Testing nNo Formal Mechanism is Defined in the Standard nCommittee for the Advancement of DICOM nDefine initial test plan and cross-connect matrix nFuture RFP for organization to monitor the process nProblem: How to Map DICOM Conformance Statements into Test Plans

The DICOM Explosion nJoint CEN-DICOM development nMedicom = DICOM nMIPS 95 work is underway with JIRA nIS&C Harmonization is also in progress nHL7 Harmonization continuing interest nNew DICOM organization uCompanies: NEMA and non-NEMA uACR, ACC, CAP,... uindividuals

Summary nNetworking is a critical component of all medical imaging systems nSupport for Open Communication Standards is a MUST nDICOM is here, NOW nDICOM products exist on the market nDICOM is emerging as THE common protocol for medical image communication - WORLD WIDE!