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
LLCMAC
PHYSICAL
DATA LINK
NETWORK
TRANSPORT
SESSION
PRESENTATION
APPLICATION
Fiber, Coax, UTP, µWave
End-to-End communication
Data Formatting, Compression,Encryption
File Transfer, E-mail, HTTP
Ethernet, FDDI, etc.
Internetworking
Upper Layers(DICOM)
Synchronization,Comm. Management
Lower Layers
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? User 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 joint 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 Support for Message Exchange Part 9 - Point-to-Point Support
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
MAGN
ETOM
Information Management System
Storage, Query/RetrieveStorage, Query/Retrieve , ,Study ComponentStudy Component
Query/Retrieve, Patient & Study ManagementQuery/Retrieve, Patient & Study Management
Query/RetrieveQuery/RetrieveResults ManagementResults Management
Print ManagementPrint Management
Media ExchangeMedia Exchange
LiteBox
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 supports 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 Support 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
SOPSOP
Data DictionaryData Dictionary
Real-World ObjectReal-World Object
Information ObjectInformation Object DIMSE Service GroupDIMSE Service Group
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 supported 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 supported policies for initiation and acceptance of associations
Presentation Contexts SOP options Supported communications protocols Specializations Configuration
Purpose of a Conformance Statement Allow 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.
By comparing the Conformance Statements from two implementations, a knowledgeable user 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 Joint 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 Support 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!