DICOM PS3.3 2021b - Information Object Definitions

3 Definitions (Current)
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# 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 [ISO 7498-2] and makes use of the following terms defined in them:

Application Entity (AE)

  See [ISO 7498-1].

Service

  See [ISO 7498-1].

## 3.2 Service Conventions Definitions

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

Primitive

  See [ISO/TR 8509].

## 3.3 DICOM Introduction and Overview Definitions

This Part of the Standard makes use of the following terms defined in PS3.1:

Attribute

  Attribute.

Command

  Command.

Data Dictionary

  Data Dictionary.

Message

  Message.

Service-Object Pair Class (SOP Class)

  Service-Object Pair Class (SOP Class).

## 3.4 DICOM Service Class Specifications

This Part of the Standard makes use of the following terms defined in PS3.4:

Real-World Activity

  Real-World Activity.

Real-World Object

  Real-World Object.

Service Class

  Service Class.

Service Class User (SCU)

  Service Class User (SCU).

Service Class Provider (SCP)

  Service Class Provider (SCP).

Service-Object Pair Instance (SOP Instance)

  Service-Object Pair Instance (SOP Instance).

Preformatted Grayscale Image

  Preformatted Grayscale Image.

Preformatted Color Image

  Preformatted Color Image.

Related General SOP Class

  Related General SOP Class.

## 3.5 DICOM Data Structures and Encoding

This Part of the Standard makes use of the following terms defined in PS3.5:

Basic Offset Table (BOT)

  Basic Offset Table (BOT).

Data Element

  Data Element.

Data Element Tag

  Data Element Tag.

Data Element Type

  Data Element Type.

Data Set

  Data Set.

Defined Term

  Defined Term.

Enumerated Value

  Enumerated Value.

Extended Offset Table (EOT)

  Extended Offset Table (EOT).

Sequence of Items

  Sequence of Items.

Unique Identifier (UID)

  Unique Identifier (UID).

## 3.6 DICOM Message Exchange

This Part of the Standard makes use of the following terms defined in PS3.7:

DICOM Message Service Element (DIMSE)

  DICOM Message Service Element (DIMSE).

DIMSE-N Services

  DIMSE-N Services.

DIMSE-C Services

  DIMSE-C Services.

## 3.7 DICOM Upper Layer Service

This Part of the Standard makes use of the following terms defined in PS3.8:

DICOM Upper Layer Service

  DICOM Upper Layer Service.

## 3.8 DICOM Information Object

Acquisition Context

  A description of the conditions present during data acquisition.

Acquisition Protocol Element

  A sequential component of the acquisition portion of a protocol, that contains the parameters necessary to perform a single acquisition. In the case of CT, this would correspond to tube voltage, tube current, rotation time, spatial location, etc. and an Acquisition Protocol Element also corresponds to an [NEMA XR-25] PROTOCOL ELEMENT. In the case of XA, this would correspond to technical factors and control algorithms for the image acquisition, e.g. kVp, mA, pulse width, image quality targets, rotation range, etc.

Assertion

  An affirmative statement or declaration by a specified entity about a specified or implied subject for a specified or implied purpose.

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).

Basic Directory IOD

  The Basic Directory Information Object Definition is an abstraction of the information to identify a File-set and facilitate access to the information stored in the files of a File-set based on key medical information.

Basic Directory Information Model

  A model that defines the relationship between the various types of Directory Records that may be used in constructing DICOM Directories.

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.

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. Section 8.1 through Section 8.8 specify the Attributes of which the Sequence Items (Attribute Sets) of Code Sequence Attributes are constructed.

Composite IOD

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

Derived Image

  An image in which the pixel data was constructed from pixel data of one or more other images (source images).

DICOM Application Model

  An Entity-Relationship diagram used to model the relationships between Real-World Objects that are within the area of interest of the DICOM Standard.

DICOM Information Model

  An Entity-Relationship diagram that is used to model the relationships between the Information Object Definitions representing classes of Real-World Objects defined by the DICOM Application Model.

Functional Group

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

Information Entity

  That portion of information defined by a Composite IOD that 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.

Information Object Definition (IOD)

  A data abstraction of a class of similar Real-World Objects that defines the nature and Attributes relevant to the class of Real-World Objects represented.

Module

  A set of Attributes within an Information Entity or Normalized IOD that are logically related to each other.

Multi-frame Image

  Image that contains multiple two-dimensional pixel planes.

Normalized IOD

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

Protocol Element

  A sequential component of a protocol, consisting of all the parameters necessary to perform that component of the protocol.

Reconstruction Protocol Element

  A sequential component of the reconstruction portion of a protocol, such as generating CT thin images or multiplanar reformats, or generating XA 2D processed images and/or 3D X-Ray images.

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".

Storage Protocol Element

  A sequential component of the storage portion of protocol, such as sending a Series of images to a PACS or an archive or a processing workstation.

## 3.9 Character Handling Definitions

This Part of the standard makes use of the following terms defined in [ISO/IEC 2022]:

Coded Character Set

  See [ISO/IEC 2022].

Code Extension

  See [ISO/IEC 2022].

Escape Sequence

  See [ISO/IEC 2022].

## 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:

FIXED REFERENCE System

  See [IEC 61217].

GANTRY System

  See [IEC 61217].

BEAM LIMITING DEVICE System

  See [IEC 61217].

WEDGE FILTER system

  See [IEC 61217].

X-RAY IMAGE RECEPTOR System

  See [IEC 61217].

PATIENT SUPPORT System

  See [IEC 61217].

TABLE TOP ECCENTRIC System

  See [IEC 61217].

TABLE TOP System

  See [IEC 61217].

## 3.11 Macros

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

This Part of the Standard makes use of the following terms defined in PS3.14:

P-Value

  P-Value.

Profile Connection Space Value (PCS-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 PS3.16:

Baseline Context Group Identifier (BCID)

  Baseline Context Group Identifier (BCID).

Defined Context Group Identifier (DCID)

  Defined Context Group Identifier (DCID).

Context Group

  Context Group.

Context Group Version

  Context Group Version.

Context ID (CID)

  Context ID (CID).

Mapping Resource

  Mapping Resource.

Relationship Type

  Relationship Type.

DICOM Content Mapping Resource (DCMR)

  DICOM Content Mapping Resource (DCMR).

Template

  Template.

Template ID (TID)

  Template ID (TID).

Value Set

  Value Set.

Baseline Template Identifier (BTID)

  Baseline Template Identifier (BTID).

Defined Template Identifier (DTID)

  Defined Template Identifier (DTID).

Coding Scheme

  Coding Scheme.

## 3.14 Reference Model Security Architecture Definitions

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

Digital Signature

  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."

Data Confidentiality

  The definition is "the property that information is not made available or disclosed to unauthorized individuals, entities or processes."

Data Origin Authentication

  The definition is "the corroboration that the source of data received is as claimed."

Data Integrity

  The definition is "the property that data has not been altered or destroyed in an unauthorized manner."

Key Management

  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]:

Security Context

  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 PS3.15:

Message Authentication Code (MAC)

  Message Authentication Code.

Certificate

  Certificate.

## 3.17 Multi-dimensional Definitions

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.

Ophthalmic Coordinate System (OCS)

  The Ophthalmic Coordinate System is used as the Frame of Reference that establishes the spatial relationship relative to the corneal vertex. The corneal vertex is the point located at the intersection of the patient's line of sight (visual axis) and the corneal surface. See Section C.8.30.3.1.4 for further explanation.

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 collections of data is a common means to establish the spatial relationship between similar objects.

Fiducial Point

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

Multi-Planar Reconstruction (MPR)

  Also called Multi-Planar Reformatting. A data visualization created by sampling volume data, typically represented by a stack of image planes, that lies in the neighborhood of the intersection of the volume with a plane, curved plane, slab or curved slab.

Planar Multi-Planar Reconstruction (Planar MPR)

  An MPR where the samples are centered on a single plane intersected with the volume.

Volumetric Presentation State (VPS)

  A Presentation State that defines a transformation from 3D spatial input data (volume) to 2D spatial output data, with or without affecting other dimensions such as temporal.

Volumetric Presentation State Reference Coordinate System (VPS-RCS)

  The Reference Coordinate System to which inputs to a Volumetric Presentation State are registered and to which Attribute Values of a Volumetric Presentation State are referenced (unless stated otherwise).

Volumetric Presentation View

  A presentation, with two spatial dimensions, of volume data.

## 3.18 Display Equipment Definitions

This Part of the Standard makes use of the following terms, some of which are defined in PS3.14 or [IEC 62563-1]:

Display System

  Display System.

Display Subsystem

  A part of a Display System. A Display Subsystem consists of one Display Device and zero or more other devices (such as controllers). A Display System has one or more Display Subsystems.

Display Device

  See [IEC 62563-1].

  ### Note

  The definition is "specific hardware/medium used to display images presented through an analogue or digital interface".

## 3.19 Digital Input Values To Display Systems

This Part of the Standard makes use of the following terms defined in PS3.14:

Digital Driving Level (DDL)

  Digital Driving Level (DDL).

## 3.20 Device Identification Definitions

Unique Device Identifier (UDI)

  An alphanumeric identifier issued by the unique device identification system established by the FDA to label and identify devices through distribution and use. See http://www.fda.gov/udi.

## 3.21 Structured Report Definitions

Content Item

  A node in the Content Tree of a DICOM SR document, consisting of either a container with a coded Concept Name, or a name-value pair with a coded Concept Name and a Concept Value.

Content Tree

  The tree of Content Items of a DICOM SR document.

## 3.22 Miscellaneous Definitions

Externally-Sourced Data Set

  A collection of data that has been obtained from or is defined by an entity separate from the system creating an object.

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DICOM PS3.3 2021b - Information Object Definitions