DICOM PS3.3 2023a - Information Object Definitions

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

See Attribute in PS3.1 .

Command

See Command in PS3.1 .

Data Dictionary

See Data Dictionary in PS3.1 .

Message

See Message in PS3.1 .

Service-Object Pair Class (SOP Class)

See Service-Object Pair Class in PS3.1 .

3.4 DICOM Service Class Specifications

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

Real-World Activity

See Real-World Activity in PS3.4 .

Real-World Object

See Real-World Object in PS3.4 .

Service Class

See Service Class in PS3.4 .

Service Class User (SCU)

See Service Class User in PS3.4 .

Service Class Provider (SCP)

See Service Class Provider in PS3.4 .

Service-Object Pair Instance (SOP Instance)

See Service-Object Pair Instance in PS3.4 .

Preformatted Grayscale Image

See Preformatted Grayscale Image in PS3.4 .

Preformatted Color Image

See Preformatted Color Image in PS3.4 .

Related General SOP Class

See Related General SOP Class in PS3.4 .

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)

See Basic Offset Table in PS3.5 .

Data Element

See Data Element in PS3.5 .

Data Element Tag

See Data Element Tag in PS3.5 .

Data Element Type

See Data Element Type in PS3.5 .

Data Set

See Data Set in PS3.5 .

Defined Term

See Defined Term in PS3.5 .

Enumerated Value

See Enumerated Value in PS3.5 .

Extended Offset Table (EOT)

See Extended Offset Table in PS3.5 .

Sequence of Items

See Sequence of Items in PS3.5 .

Unique Identifier (UID)

See Unique Identifier in PS3.5 .

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)

See DICOM Message Service Element in PS3.7 .

DIMSE-N Services

See DIMSE-N Services in PS3.7 .

DIMSE-C Services

See DIMSE-C Services in PS3.7 .

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

See DICOM Upper Layer Service in PS3.8 .

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.

Annotation

Additional information associated with an object.

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.

Inventory

A listing of DICOM Studies, Series, and SOP Instances, and associated metadata, managed by a repository system.

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.

Region of Interest (ROI)

A selected subset of samples within a dataset identified for a particular purpose.

Scope of Inventory

The parameters that select the DICOM Studies that are included in an Inventory. Parameters are specified as matching rules for Attribute values.

Segment

A part of a whole, such as the classification of pixels in an image.

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.

Structure Set

A set of areas of significance.

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

See P-Value in PS3.14 .

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)

See Baseline Context Group Identifier in PS3.16 .

Defined Context Group Identifier (DCID)

See Defined Context Group Identifier in PS3.16 .

Context Group

See Context Group in PS3.16 .

Context Group Version

See Context Group Version in PS3.16 .

Context ID (CID)

See Context ID in PS3.16 .

Mapping Resource

See Mapping Resource in PS3.16 .

Relationship Type

See Relationship Type in PS3.16 .

DICOM Content Mapping Resource (DCMR)

See DICOM Content Mapping Resource in PS3.16 .

Template

See Template in PS3.16 .

Template ID (TID)

See Template ID in PS3.16 .

Value Set

See Value Set in PS3.16 .

Baseline Template Identifier (BTID)

See Baseline Template Identifier in PS3.16 .

Defined Template Identifier (DTID)

See Defined Template Identifier in PS3.16 .

Coding Scheme

See Coding Scheme in PS3.16 .

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)

See Message Authentication Code in PS3.15 .

Certificate

See Certificate in PS3.15 .

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

See Display System in PS3.14 .

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)

See Digital Driving Level in PS3.14 .

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.

3.23 DICOM Media Storage and File Format

This Part of the Standard makes use of the following terms defined in PS3.10:

DICOM File Format

See DICOM File Format in PS3.10 .

DICOM PS3.3 2023a - Information Object Definitions