Each Composite IOD is composed of the following Sections
-
Optionally, a Functional Group Macros Table used by the Multi-frame Functional Groups Module
Section A.1.1, Section A.1.2 and Section A.1.3 define the requirements of a) through d) above.
This Section of an IOD provides the Entity-Relationship (E-R) Model that depicts the relationships of the components or Information Entities (IE) of the specified IOD. It forms an IOD specific information model. This E-R model provides the complete context of how the Composite Instance information shall be interpreted when a Composite Instance is exchanged between two DICOM Application Entities; in particular, an IOD will specify a single IE at the level below the Series IE.
Even though Composite Instances are encoded as discrete individual components, each Composite Instance IOD E-R Model requires that all Composite Instances that are part of a specific Study shall share the same context. That is, all Composite Instances within a specific Patient Study share the same Patient and Study information; all Composite Instances within the same Series share the same Series information; etc.
Figure A.1-1 is the DICOM Composite Instance IOD Information Model. It applies to all Patient-related Composite Instance IODs defined in Annex A. However, a subset of this model may be specified by each individual Composite Instance IOD to accurately define the context for specific Composite Instance exchange.
The sub-sections of this Section describe the Information Entities (IE) that comprise the Composite Instance IODs defined in this Annex.
The Patient IE defines the characteristics of a Patient who is the subject of one or more medical Studies.
The Study IE defines the characteristics of a medical Study performed on a Patient. A Study is a collection of one or more Series of medical images, presentation states, and/or SR documents that are logically related for the purpose of diagnosing a Patient. Each Study is associated with exactly one Patient.
A Study may include Composite Instances that are created by a single modality, multiple modalities or by multiple devices of the same modality.
The Series IE defines the Attributes that are used to group Composite Instances into distinct logical sets. Each Series is associated with exactly one Study.
The following criteria group Composite Instances into a specific Series:
-
All Composite Instances within a Series must be of the same modality
-
Each Series may be associated with exactly one Frame of Reference IE, and if so associated all Composite Instances within the Series shall be spatially or temporally related to each other
-
All Composite Instances within the Series shall be created by the same equipment; therefore, each Series is associated with exactly one Equipment IE
-
All Composite Instances within a Series shall have the same Series information
Presentation States shall be grouped into Series without Images (i.e., in a different Series from the Series containing the Images to which they refer).
Note
The Series containing Grayscale, Color and Pseudo-Color Softcopy Presentation States and the Series containing the Images to which they refer are both contained within the same Study, except for Blended Presentation States, which may refer to images from different Studies.
Waveforms shall be grouped into Series without Images. A Frame of Reference IE may apply to both Waveform Series and Image Series.
SR Documents shall be grouped into Series without Images. The Frame of Reference IE may apply to SR Document Series, for SR Documents that contain 3D spatial coordinates relative to one or more spatial Frames of Reference, or temporal coordinates that require a temporal Frame of Reference.
The Equipment IE describes the particular device that produced the Series of Composite Instances. A device may produce one or more Series within a Study. The Equipment IE does not describe the data acquisition or image creation Attributes used to generate the Composite Instances within a Series. These Attributes are described in the Composite Instance specific IEs (e.g., the Image IE).
The Frame of Reference IE identifies the coordinate system that conveys spatial and/or temporal information of Composite Instances in a Series.
When present, a Frame of Reference IE may be related to one or more Series. In this case, it provides the ability to spatially or temporally relate multiple Series to each other. In such cases, the Series may share the UID of the Frame of Reference, or alternatively, a Registration SOP Instance may specify the spatial relationship explicitly, as a spatial transformation. A Frame of Reference IE may also spatially register a Frame of Reference to an atlas.
The Image IE defines the Attributes that describe the pixel data of an image. The pixel data may be generated as a direct result of Patient scanning (termed an Original Image) or the pixel data may be derived from the pixel data of one or more other images (termed a Derived Image). An image is defined by its image plane, pixel data characteristics, gray scale and/or color mapping characteristics and modality specific characteristics (acquisition parameters and image creation information).
An image is related to a single Series within a single Study.
The pixel data within an Image IE may be represented as a single frame of pixels or as multiple frames of pixel data. The frames of a Multi-frame Image (a Cine Run or the slices of a volume) are sequentially ordered and share a number of common properties. A few Attributes may vary between frames (e.g., Time, Angular Displacement, Slice Increment). All common Image IE Attributes refer to the first frame of a multiple frame image.
Overlay, Modality and Value of Interest Lookup Table and Real World Value Mapping data may be included within an Image IE only if this information is directly associated with the image.
Overlay data represents graphics or text in a bit-map format, and is used to indicate such items as region of interest, reference marks and annotations.
Modality LUT data describes the transformation of manufacturer dependent pixel values into pixel values that are manufacturer independent (e.g., Hounsfield units for CT, Optical Density for film digitizers, etc.). The transformation may be linear, described by Rescale Slope (0028,1053) and Rescale Intercept (0028,1052), or non-linear, described by a Lookup Table (LUT).
The Value of Interest (VOI) LUT data describes the transformation of the modality pixel values into pixel values that are meaningful for print, display, etc. This transformation is applied after any Modality LUT. The transformation may be linear, described by Window Center and Window Width, or non-linear, described by a Lookup Table. A non-linear interpretation of Window Center and Window Width may be defined by VOI LUT Function.
The Real World Value Mapping data describes the transformation of the image pixel values into Real World Values in defined units. There may be multiple transformations, each scoped by a range of input pixel values. Each transformation may be linear, described by Slope and Intercept, or non-linear, described by a Lookup Table.
Retired. See PS3.3-2016a.
Note
Overlays were previously modeled as independent Information Entities; in the current model they are considered Attributes within the Image IE or Presentation State IE. See A.1.2.6.1.
Retired. See PS3.3-2004.
Retired. See PS3.3-2016a.
Note
Modality LUTs were previously modeled as independent Information Entities; in the current model they are considered Attributes within the Image IE or Presentation State IE. See A.1.2.6.2.
Retired. See PS3.3-2016a.
Note
VOI LUTs were previously modeled as independent Information Entities; in the current model they are considered Attributes within the Image IE or Presentation State IE. See A.1.2.6.3.
The Presentation State IE defines how a referenced image (or images) will be presented (e.g., displayed) in a device independent grayscale space (i.e., in P-Values) or color space (i.e., in PCS-values), and what graphical annotations and spatial and grayscale contrast transformations will be applied to the referenced image pixel data.
Overlay, Modality LUT, and VOI LUT data (see A.1.2.6.1, A.1.2.6.2, and A.1.2.6.3) may be included within a Presentation State IE if this information is to be applied to the referenced image(s).
The Waveform IE represents a multi-channel time-based digitized waveform. The waveform consists of measurements of some physical qualities (e.g., electrical voltage, pressure, gas concentration, or sound), sampled at constant time intervals. The measured qualities may originate, for example, in any of the following sources:
The sample data within a Waveform IE may represent one or more acquired channels. Several signal channels acquired at the same sampling rate can be multiplexed (by interleaving samples) in a single multiplex group. (see also Annex C “Waveforms (Informative)” in PS3.17.)
The SR Document IE defines the Attributes that describe the content of an SR Document. These include semantic context as well as Attributes related to document completion, verification and other characteristics. An SR Document SOP Instance is related to a single Series within a single Study.
The Spectroscopy IE defines the Attributes that describe the data of a spectroscopy acquisition created by a magnetic resonance spectroscopy device.
The Raw Data IE defines the Attributes that describe a collection of data that may be used for further processing to produce image data or other data.
The Encapsulated Document IE defines the Attributes that describe the content of a non-DICOM formatted document that is encapsulated in a DICOM Attribute. These include Attributes related to document origin, title, and other characteristics. An Encapsulated Document SOP Instance is related to a single Series within a single Study.
The Real World Value Mapping IE defines the Attributes that describe the mapping of stored pixel data to Real World values (see A.1.2.6.4).
The Surface IE defines the Attributes that describe a surface in a spatial coordinate system. A surface is defined by its shape and can be further defined by normals on that shape. The surface may be reconstructed from either spatial scans (e.g., laser scanners) or based on images. A surface is described by its finite volume and manifold property, gray scale and color mapping characteristics, presentation type, opacity, and modality specific characteristics.
The Measurements IE defines the Attributes that describe the measurements taken by medical instruments.
The Tractography Results IE defines the Attributes that describe the results of a tractography application.
The Plan IE defines the parameters and instructions to deliver treatment, particularly Radiotherapy, to the Patient. The entity includes the set of machine and positioning parameters to be applied during treatment delivery and instructions guiding the treatment workflow.
The Content Assessment Result IE contains the results of an assessment of the content of a SOP Instance.
An assessment is part of a process within a clinical workflow, conducted by users or devices, which have the role of assessing the validity and suitability of the content in question, based on subjective or objective criteria. The specific nature of such a process is outside of the scope of this Standard.
The Spatial Fiducials IE identifies one or more geometric locations or shapes within a Frame of Reference or image pixel/voxel space that may be correlated with similar locations or shapes within different frames of reference or image pixel/voxel spaces.
The Dose IE describes dose distributions calculated by radiotherapy treatment planning systems. These distributions may be represented as 2D or 3D grids, as isodose curves, or as named or unnamed dose points scattered throughout a volume.
The Structure Set IE describes Regions of Interest (ROI) within a referenced 2D (image) or 3D (volumetric) space. These ROIs may be represented as geometric contours.
The Procedure Protocol IE defines the Attributes that describe a Protocol. This IE may encode a Defined Procedure Protocol or a Performed Procedure Protocol.
The Acquisition IE defines the Attributes that describe a single continuous gathering of data.
An Acquisition may result in more than one Series, and a Series may contain Instances from more than one Acquisition.
The Multi-Resolution Pyramid IE describes a set of Images that encode the same image data at different spatial resolutions, i.e., a base (highest resolution) layer that is successively smoothed and down-sampled to create additional lower resolution layers (a multi-resolution decomposition).
Note
No specific method of filtering or down-sampling is specified by the Standard, nor is there a requirement for any specific down-sampling factor between layers, nor that an integer factor be used.
Each layer is encoded as a separate DICOM Image, each of which has a uniform resolution (same value for Pixel Spacing (0028,0030)). Layers may be tiled, with each tile encoded as a frame of a Multi-frame Image.
All DICOM Image SOP Instances that constitute a single Multi-Resolution Pyramid shall share the same Frame of Reference, and shall be contained in the same Series.
Only one Multi-Resolution Pyramid shall be contained in a Series (i.e., each such Multi-Resolution Pyramid will be in a different Series).
Note
-
In historical usage, there is no Multi-Resolution Pyramid IE and thus a Series is not constrained to contain only a single conceptual pyramid. However, any instantiation of the Multi-Resolution Pyramid in a Series constrains the Series to one Multi-Resolution Pyramid.
-
Each Multi-Resolution Pyramid may be accompanied in the same Series by LABEL, OVERVIEW and THUMBNAIL images if they share the same Frame of Reference (but not otherwise, per the definition of the Series IE). The THUMBNAIL image rather than a VOLUME image may be the apex (lowest resolution layer) of the Multi-Resolution Pyramid.
-
A unique identifier, Pyramid UID (0008,0019) will be assigned to an instance of a Multi-Resolution Pyramid, and will be shared by all of the layers that constitute that instance of a Multi-Resolution Pyramid, whether or not a particular resolution layer (usually the highest resolution) is deemed to be ORIGINAL, and the lower resolution layers DERIVED (e.g., by some down-sampling image processing operation). By definition, the absence of Pyramid UID (0008,0019) implies the absence of instantiation of the Multi-Resolution Pyramid IE.
That use is distinct from the Pyramid UID (0008,0019) of different Multi-Resolution Pyramids that may be further derived from a Multi-Resolution Pyramid. In otherwords, the Pyramid UID (0008,0019) of a Multi-Resolution Pyramid will not be shared between two pyramids that contain different pixel data (other than differences due to lossless representation of the same pixel data in different Transfer Syntaxes).
This Section of each IOD defines in a tabular form the Modules comprising the IOD. The following information must be specified for each Module in the table:
-
A reference to the Section in Annex C that defines the Module or Functional Group
-
The usage of the Module or Functional Group; whether it is:
-
Mandatory (see Section A.1.3.1), abbreviated M
-
Conditional (see Section A.1.3.2), abbreviated C
-
User Option (see Section A.1.3.3), abbreviated U
-
The Modules referenced are defined in Annex C.
For each IOD, Mandatory Modules shall be supported per the definitions, semantics and requirements defined in Annex C.
Conditional Modules are Mandatory Modules if specific conditions are met. If the specified conditions are not met, this Module shall not be supported; that is, no information defined in that Module shall be present.
User Option Modules may or may not be supported. If an optional Module is supported, the Attribute Types specified in the Modules in Annex C shall be supported.
The Tables in this Section provide an overview of the Modules used throughout the Composite IODs. This table is for informative purposes only. It is based on the IOD definitions found in the remaining Sections of Annex A that are normative.
Table A.1-1a. Composite Information Object Modules Overview - Images
|
Enhanced Patient Orientation |
U |
U |
U |
U |
U |
U |
U |
U |
U |
U |
U |
|||||||
* The notation next to M and U indicates a special condition for these Modules. Refer to the corresponding IODs in this Annex for details.
Note
-
The original Ultrasound Image IOD and Ultrasound Multi-frame IOD, and the associated Ultrasound Image Storage SOP Class UID and Ultrasound Multi-frame Image Storage SOP Class UID have been retired. A new Ultrasound Image IOD and a new Ultrasound Multi-frame Image IOD are defined, as shown in Table A.1-1a, which includes the Palette Color Lookup Table Module.
-
The original Nuclear Medicine Image IOD and the associated Nuclear Medicine Image Storage SOP Class UID have been retired. A completely new Nuclear Medicine Image IOD is defined, as shown in Table A.1-1a.
Table A.1-1d. Composite Information Object Modules Overview - More Images
Table A.1-1e. Composite Information Object Modules Overview - More Images
|
Leg Conv Enh CT |
Leg Conv Enh MR |
Leg Conv Enh PET |
||||
|---|---|---|---|---|---|---|
|
M |
M |
M |
||||
|
U |
U |
U |
||||
|
M |
M |
M |
||||
|
U |
U |
U |
||||
|
U |
U |
U |
||||
|
M |
M |
M |
||||
|
U |
U |
U |
||||
|
CT Series |
M |
|||||
|
MR Series |
M |
|||||
|
Enhanced PET Series |
M |
|||||
|
M |
M |
M |
||||
|
U |
U |
U |
||||
|
U |
U |
U |
||||
|
Respiratory Synchronization |
U |
U |
U |
|||
|
Bulk Motion Synchronization |
U |
|||||
|
M |
M |
M |
||||
|
U |
U |
U |
||||
|
M |
M |
M |
||||
|
Contrast/Bolus |
U |
U |
||||
|
U |
U |
|||||
|
M |
M |
M |
||||
|
U |
U |
U |
||||
|
U |
U |
|||||
|
U |
U |
U |
||||
|
Intervention |
U |
|||||
|
Enhanced CT Image |
M |
|||||
|
Enhanced MR Image |
M |
|||||
|
Enhanced PET Image |
M |
|||||
|
M |
M |
M |
||||
|
M |
M |
M |
||||
|
M |
M |
M |
||||
|
C |
C |
C |
Table A.1-2. Composite Information Object Modules Overview - Non-Images
|
Enhanced Patient Orientation |
U |
|||||
Table A.1-3. Composite Information Object Modules Overview - More Non-Images