Download 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
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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
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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-toPoint
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 multiframe 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 Application Entities
– SOP Classes supported
– policies for initiation and acceptance of
associations
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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
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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!