3 Definitions

For the purposes of this Standard the following definitions apply.

3.1 Reference model definitions

This Part of the Standard is based on the concepts developed in ISO 7498-1 and makes use of the following terms defined in it:

a. Application Entity

b. Service or Layer Service

This Part of the Standard makes use of the following terms defined in ISO 7498-2:

a. Data Confidentiality

Note: The definition is “the property that information is not made available or disclosed to unauthorized individuals, entities or processes.”

b. Data Origin Authentication

Note: The definition is “the corroboration that the source of data received is as claimed.”

c. Data Integrity

Note: The definition is “the property that data has not been altered or destroyed in an unauthorized manner.”

d. Key Management

Note: The definition is “the generation, storage, distribution, deletion, archiving and application of keys in accordance with a security policy.”

3.2 Service conventions definitions

This Part of the Standard makes use of the following terms defined in ISO/TR 8509:

a. Primitive

3.3 DICOM introduction and overview definitions

This Part of the Standard makes use of the following terms defined in PS 3.1:

a. Attribute

b. Command

c. Data Dictionary

d. Message

3.4 DICOM service class specifications

This Part of the Standard makes use of the following terms defined in PS 3.4:

a. Real-World Activity

b. Real-World Object

c. Service Class

d. Service Class User

e. Service Class Provider

f. Service-Object Pair (SOP) Class

g. Service-Object Pair (SOP) Instance

h. Preformatted Grayscale Image

i. Preformatted Color Image

j. Related General SOP Class

3.5 DICOM DATA STRUCTURES AND ENCODING

This Part of the Standard makes use of the following terms defined in PS 3.5:

a. Data Element

b. Data Element Tag

c. Data Element Type

d. Data Set

e. Defined Term

f. Enumerated Value

g. Sequence of Items

h. Unique Identifier (UID)

3.6 DICOM message exchange

This Part of the Standard makes use of the following terms defined in PS 3.7:

a. DICOM Message Service Element (DIMSE)

b. DIMSE-N Services

c. DIMSE-C Services

3.7 DICOM upper layer service

This Part of the Standard makes use of the following terms defined in PS 3.8:

a. DICOM Upper Layer Service

3.8 DICOM Information Object

The following definitions are commonly used in this part of the Standard:

3.8.1 Attribute tag: A unique identifier for an Attribute of an Information Object composed of an ordered pair of numbers (a Group Number followed by an Element number).

3.8.2 Composite IOD: an Information Object Definition which represents parts of several entities in the DICOM Application Model. Such an IOD includes Attributes which are not inherent in the Real-World Object that the IOD represents but rather are inherent in related Real-World Objects.

3.8.3 Derived image: an image in which the pixel data was constructed from pixel data of one or more other images (source images).

3.8.4 DICOM information model: an Entity-Relationship diagram which is used to model the relationships between the Information Object Definitions representing classes of Real-World Objects defined by the DICOM Application Model.

3.8.5 DICOM application model: an Entity-Relationship diagram used to model the relationships between Real-World Objects which are within the area of interest of the DICOM Standard.

3.8.6 Information entity: that portion of information defined by a Composite IOD which is related to one specific class of Real-World Object. There is a one-to-one correspondence between Information Entities and entities in the DICOM Application Model .

3.8.7 Information object definition (IOD): a data abstraction of a class of similar Real-World Objects which defines the nature and Attributes relevant to the class of Real-World Objects represented.

3.8.8 Module: A set of Attributes within an Information Entity or Normalized IOD which are logically related to each other.

3.8.9 Multi-frame image: Image that contains multiple two-dimensional pixel planes.

3.8.10 Normalized IOD: an Information Object Definition which represents a single entity in the DICOM Application Model. Such an IOD includes Attributes which are only inherent in the Real-World Object that the IOD represents.

3.8.11 Cine run: A set of temporally related frames acquired at constant or variable frame rates. This term incorporates the general class of serialography .

Note: A Cine run is typically encoded as a multi-frame image.

  1. Specialization: Specialization is the replacement of the Type, value range and/or description of an Attribute in a general Module of an IOD, by its Type, value range and/or description defined in a modality-specific Module of an IOD.

Note: The same Attribute may be present in multiple Modules in the same IOD but not specified to be “Specialized”.

  1. Functional Group: A set of logically related Attributes that are likely to vary together. May be used in Multi-frame IODs to describe parameters which change on a per frame basis.

  2. Code Sequence Attribute: Attribute that (usually) includes the string "Code Sequence" in the Attribute Name and has a VR of SQ (Sequence of Items). Its purpose is to encode concepts using code values and optional text meanings from coding schemes. Sections 8.1 through 8.8 specify the Attributes of which the Sequence Items (Attribute Sets) of Code Sequence Attributes are constructed.

3.9 Character Handling Definitions

This part of the standard makes use of the following terms defined in ISO/IEC 2011:1994:

a. Coded character set; code.

b. Code extension;

c. Escape sequence.

3.10 Radiotherapy

This Part of the Standard is based on the concepts developed in IEC 61217 and makes use of the following terms defined in it:

a. FIXED REFERENCE system

b. GANTRY system

c. BEAM LIMITING DEVICE system

d. WEDGE FILTER system

e. X-RAY IMAGE RECEPTOR system

f. PATIENT SUPPORT system

g. TABLE TOP ECCENTRIC system

h. TABLE TOP system

3.11 Macros

3.11.1 Attribute Macro: a set of Attributes that are described in a single table that is referenced by multiple Module or other tables.

3.12 Device Independent Pixel Values

3.12.1 P-Value

This Part of the Standard makes use of the following terms defined in PS 3.14:

a. P-Value

Note: The definition is " A device independent value defined in a perceptually linear grayscale space. The output of the DICOM Presentation LUT is P-Values, i.e. the pixel value after all DICOM defined grayscale transformations have been applied. P-Values are the input to a Standardized Display System."

3.12.2 PCS-Value: Profile Connection Space Value. A device independent color value that is created by the application of the transformation specified in an ICC profile.

3.13 Codes and Controlled Terminology Definitions:

This Part of the Standard makes use of the following terms defined in PS 3.16:

  1. Baseline Context Group Identifier (BCID)

  2. Defined Context Group Identifier (DCID)

  3. Context Group

  4. Context Group Version

  5. Context ID (CID)

  6. Mapping Resource

  7. Relationship Type

  8. DICOM Content Mapping Resource (DCMR)

  9. Template

  10. Template ID (TID)

  11. Value Set

  12. Baseline Template Identifier (BTID)

  13. Defined Template Identifier (DTID)

  14. Coding schemes

3.14 REFERENCE MODEL SECURITY ARCHITECTURE DEFINITIONS

This Part of the Standard makes use of the following terms defined in ISO 7498-2:

  1. Digital Signature

Note: The definition is “Data appended to, or a cryptographic transformation of, a data unit that allows a recipient of the data unit to prove the source and integrity of that unit and protect against forgery e.g. by the recipient.”

  1. Data Confidentiality

Note: The definition is “the property that information is not made available or disclosed to unauthorized individuals, entities or processes.”

  1. Data Origin Authentication

Note: The definition is “the corroboration that the source of data received is as claimed.”

  1. Data Integrity

Note: The definition is “the property that data has not been altered or destroyed in an unauthorized manner.”

  1. Key Management

Note: The definition is “the generation, storage, distribution, deletion, archiving and application of keys in accordance with a security policy.”

3.15 Security Definitions

This Part of the Standard makes use of the following terms defined in ECMA 235:

  1. Security Context

Note: The definition is “security information that represents, or will represent a Security Association to an initiator or acceptor that has formed, or is attempting to form such an association.”

3.16 DICOM security profiles

This part of the Standard makes use of the following terms defined in PS 3.15:

  1. Message Authentication Code

  2. Certificate

3.17 Multi-Dimensional Definitions

3.17.1 Reference Coordinate System (RCS) : The RCS is the spatial coordinate system in a DICOM Frame of Reference. It is the chosen origin, orientation and spatial scale of an Image IE in a Cartesian space. The RCS is a right-handed Cartesian coordinate system i.e. the vector cross product of a unit vector along the positive x-axis and a unit vector along the positive y-axis is equal to a unit vector along the positive z-axis. The unit length is one millimeter. Typically, the Image IE contains a spatial mapping that specifies the relationship of the image samples to the Cartesian spatial domains of the RCS.

3.17.2 Fiducial: A fiducial is some unique feature or landmark suitable as a spatial reference or correlation between similar objects. The fiducial may contribute to the definition of the origin and orientation of a chosen coordinate system. Identifying fiducials in different data sets is a common means to establish the spatial relationship between similar objects.

3.17.3 Fiducial Point: A Fiducial Point defines a specific location of a Fiducial. A Fiducial Point is relative an image or to an RCS.