DICOM is a standard for digital imaging and communications in medicine. It was developed by NEMA and ACR to enable sharing of medical images and associated data between devices. DICOM defines formats for images, communication protocols, and a data model for medical imaging applications. It allows for storage, printing, distribution, and analysis of medical images through different systems.

1. DICOM FORMAT
 BY:LOKENDER YADAV

2. What is DICOM?
 The standard for Digital Imaging and
Communications in Medicine.
 Developed by the National Electrical
Manufacturers Association (NEMA) in conjunction
with the American College of Radiology (ACR).
 Covers most image formats for all of medicine.
 Specification for messaging and communication
between imaging machines.

3. A little history
 The first version was ACR-NEMA, released in 1985.
 Its goal in developing a standard was
 To enable users to retrieve images and
associated information from digital imaging
equipment in a standard format using point-to-
point connection.
 To hide differences same across multiple image
equipment manufacturers.
 To handle developing network and image standarts,
a new standart, DICOM, was proposed in 1981.

4. DICOM Application Domain
MAGN
ETOM
Information Management System
Storage, Query/Retrieve,Storage, Query/Retrieve,
Study ComponentStudy Component
Query/RetrieveQuery/Retrieve
Results ManagementResults Management
Print ManagementPrint Management
Media ExchangeMedia Exchange
LiteBox

5. Summary of DICOM Features
 NETWORK PROTOCOL
●
DICOM incorporates negotiation to permit peers
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 supports multiple character repertoires

6. 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

7. DICOM Objects
 Things such as images, reports, and patients are all
objects and are called information objects.
 Two kinds of objects in DICOM:
 Composite objects (Old objects inherited from NEMA).
 Normalized objects (New objects defined in DICOM).
 All objects and their format constitutes Data Dictionary.
 DICOM uses UIDs to identify information objects, such as
the images, reports, or transfer syntaxes.
 The form of the UID conforms to an international
standard.
 1.2.840.10008 is the root and the same for every DICOM
UID.
 Example: UID for the DICOM explicit VR little endian
transfer syntax is 1.2.840.10008.1.2.1

8. DICOM Service Classes
 Composite
●
Verification
●
Storage
●
Query/Retrieve
●
Study Content Notification
 Normalized
●
Patient Management
●
Study Management
●
Results Management
●
Basic Print Management

9. DICOM Service Elements
 Complex services are built using service elements,
called DICOM message service elements, or DIMSEs.
 There are both composite and normalized services for
composite and normalized information objects.
 There are 5 DIMSEs that are used for composite
information objects (called DIMSE-C) and 6 that are
used for normalized information objects (called DIMSE-
N).
 Two categories of DIMSEs:
 operations (such as "store")
 notifications (such as "event report”)

10. DIMSE-C Services
 DIMSE-C services:
 Operations:
 C-Store
 C-Get
 C-Move
 C-Find
 C-Echo
 No notification services

11. DIMSE-C Services
The C-STORE service is invoked by a DIMSE-service-user to
request the storage of Composite SOP Instance information
by a DIMSE-service-user.
The C-FIND service is invoked by a DIMSE-service-user to
match a series of Attribute strings against the Attributes of
the set of SOP Instances managed by a DIMSE-service-user.
The C-FIND service returns for each match a list of requested
Attributes and their values.
The C-GET service is invoked by a DIMSE-service-user to
fetch the information for one or more information objects
from a DIMSE-service-user, based upon the Attributes
supplied by the invoking DIMSE-service-user.

12. DIMSE-C Services
The C-MOVE service is invoked by a DIMSE-
service-user to move the information for one or
more Composite SOP Instances from a DIMSE-
service-user, to a third party DIMSE-service-user,
based upon the Attributes supplied by the
invoking DIMSE-service-user.
The C-ECHO service is invoked by a DIMSE-
service-user to verify end-to-end
communications with a DIMSE-service-user.

13. DIMSE-N Services
 DIMSE-N services:
 Operations:
 N-Get
 N-Set
 N-Action
 N-Create
 N-Delete
 Notifications:
 N-Event-Report

14. DIMSE-N Services
 N-EVENT-REPORT service is invoked by a DIMSE-
service-user to report an event about a SOP Instance
to a DIMSE-service-user.
N-GET service is invoked by a DIMSE-service-user to
request the retrieval of information from a DIMSE-
service-user.
N-SET service is invoked by a DIMSE-service-user to
request the modification of information by a DIMSE-
service-user.

15. DIMSE-N Services
N-ACTION service is invoked by a DIMSE-service-
user to request a DIMSE-service-user to perform an
action.
N-CREATE service is invoked by a DIMSE-service-
user to request a DIMSE-service-user to create an
instance of a information object.
N-DELETE service is invoked by a DIMSE-service-
user to request a DIMSE-service-user to delete an
instance of a information object.

16. DICOM Service-Object Pair (SOP)
 The service classes and information objects are
combined to form SOP.
 The SOP class is the elemental unit of DICOM.
 Everything that DICOM does is based on the use of
SOP classes.

17. DICOM Service-Object Pair (SOP)
SOPSOP
Data DictionaryData Dictionary
Information ObjectInformation Object DIMSE Service ElementDIMSE Service Element

18. DICOM File Format (Overview)
A single DICOM file contains:
 A header (which stores information about
the patient's name, the type of scan, image
dimensions, etc)
 Image data (in compressed (bitmap) or
uncompressed form (jpeg, gif...))

19. DICOM File Header
 DICOM requires a 128-byte preamble (usually set to zero).
 'D', 'I', 'C', 'M' letters comes next.
 The rest is the real header information in groups.
 For example: group 0002hex is the file meta information group.

20. DICOM File Header

21. DICOM File Header
 The meaning of some fields:
 0002:0010 --> Reports the structure of the image data
 0028:0002 --> Samples Per Pixel
 0028:0004 --> Photometric Interpretation
 0028:0100 --> Bits Allocated
 ...

22. Association Services
 Before everything, Association establishment
must be done.
 During Association establishment, A DIMSE-
service-user exchanges initialization
information.
The initialization information includes:
 Application context
 DIMSE-specific user information
 DIMSE service information
 Presentation and session requirements

23. Association Services
 A-ASSOCIATE Service is invoked by a DIMSE-
service-user with related parameters to establish
an Association with another DIMSE-service-user.
 Association release is done using A-RELEASE and
A-ABORT services.