Transcript DICOM Digital Imaging COmmunications in Medicine

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?
 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
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 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
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 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!