Dicom 4ht3x

DICOM Digital Imaging Communications in Medicine

Communication Protocols: Key to Connectivity  Layered Model, each layer performs a specific function  Set of Services and Protocols  Connectivity requires sharing of a complete protocol  Communication requires a shared Semantic Context

ISO Reference Model APPLICATION

Upper Layers (DICOM)

PRESENTATION SESSION

Lower Layers

File Transfer, E-mail, HTTP Data Formatting, Compression,Encryption Synchronization,Comm. Management

TRANSPORT

End-to-End communication

NETWORK

Internetworking

DATA LINK

LLC MAC

PHYSICAL

Ethernet, FDDI, etc.

Fiber, Coax, UTP, µWave

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

Who Defines Communication Standards?  Consortia (e.g., HL7)  Organizations (e.g., NEMA, IEEE)  US Government Agencies (e.g., ANSI, NIST)  Foreign Government Agencies (e.g., CEN)  United Nations (e.g., ISO, CCITT)

ACR-NEMA  1982 - ACR and NEMA form a t committee  1985 - Publication of Version 1.0  1988 - Compression and Mag Tape Standards  1988 - Publication of Version 2.0  1989 - Began work on Network Version with HIS/RIS

DICOM  The name was changed to separate the standard from the originating body  1991 - Release of Parts 1 and 8 of DICOM  1992 - RSNA demonstration, Part 8  1993 - DICOM Parts 1-9 approved, RSNA demonstration of ALL parts  1994 - Part 10: Media Storage and File Format  1995 - Parts 11,12, and 13 plus Supplements

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

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

DICOM Application Domain Storage, Query/Retrieve, Study Component

LiteBox

MAGN ETOM

Print Management

Query/Retrieve Results Management Media Exchange Query/Retrieve, Patient & Study Management Information Management System

Summary of DICOM Features  NETWORK PROTOCOL DICOM incorporates negotiation to permit nodes to agree on the functions to be performed

 MESSAGE ENCODING DICOM defines 24 data types (V2.0 had 4) DICOM message encoding includes JPEG compression (17 varients) DICOM includes encapsulated image and multi-frame syntaxes DICOM s multiple character repertoires

Summary of DICOM Features  OBJECT DATA MODEL DICOM is based on a completely specified data model DICOM includes a robust UID mechanism

 DATA DICTIONARY DICOM includes a large number of new data elements

 SERVICE CLASSES DICOM defines classes of service for specific applications (e.g. image management, printing) and conformance levels

Summary of DICOM Features  Off-Line Media DICOM defines a directory structure and media profiles

 CONFORMANCE DICOM requires conformance statements and contains detailed conformance requirements

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

DICOM Terminology  Service 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.  Service-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 Data Dictionary Information Object

DIMSE Service Group

SOP Real-World Object

DICOM Service Classes  Composite Verification Storage Query/Retrieve Study Content Notification

 Normalized Patient Management Study Management Results Management Basic Print Management

Conformance  DICOM Part 2 specifies the structure of a conformance statement

 DICOM does not specify a test suite or a compliance verification mechanism  All DICOM implementations must be ed by a properly constructed conformance statement

DICOM Conformance Statement  Implementation Model which describes the Application Entities in the implementation  Detailed specification of each Application Entity SOP Classes ed policies for initiation and acceptance of associations  Presentation Contexts  SOP options  ed communications protocols  Specializations  Configuration

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

DICOM Conformance Testing  No Formal Mechanism is Defined in the Standard  Committee for the Advancement of DICOM  Define initial test plan and cross-connect matrix  Future RFP for organization to monitor the process  Problem: How to Map DICOM Conformance Statements into Test Plans

The DICOM Explosion  t CEN-DICOM development  Medicom = DICOM  MIPS 95 work is underway with JIRA  IS&C Harmonization is also in progress  HL7 Harmonization continuing interest  New DICOM organization Companies: NEMA and non-NEMA ACR, ACC, CAP, ... individuals

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