A.26 Digital X-Ray Image IOD
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## A.26 Digital X-Ray Image IOD

### A.26.1 DX Image IOD Description

The Digital X-Ray (DX) Image Information Object Definition specifies an image that has been created by a digital projection radiography imaging device.

### Note

1. This includes but is not limited to: chest radiography, linear and multi-directional tomography, orthopantomography and skeletal radiography. Acquisition of image data may include but is not limited to: CCD-based sensors, stimulable phosphor imaging plates, amorphous selenium, scintillation based amorphous silicon and secondary capture of film-based images.

2. Specific IODs are defined for intra-oral radiography and mammography that further specialize the DX IOD.

A DX image shall consist of the result of a single X-Ray exposure, in order to ensure that the anatomical and orientation attributes are meaningful for the image, permitting safe annotation, appropriate image processing and appropriate dissemination.

### Note

1. This requirement specifically deprecates the common film/screen and Computed Radiography practice of making multiple exposures on different areas of a cassette or plate by using lead occlusion between exposures. Such acquisitions could be separated and transformed into multiple DX images during an appropriate quality assurance step by an operator.

2. This requirement does not deprecate the acquisition of multiple paired structures during a single exposure, provided that they can be described by the relevant orientation Attributes. For example, an AP or PA projection of both hands side by side is typically obtained in a single exposure, and can be described by a Patient Orientation (0020,0020) of R\H or L\H since both hands are in the same traditional Anatomical Position. See Annex A “Explanation of Patient Orientation (Normative)” in PS3.17.

The DX Image IOD is used in two SOP Classes as defined in PS3.4 Storage Service Class, a SOP Class for storage of images intended for presentation, and a SOP Class for storage of images intended for further processing before presentation. These are distinguished by their SOP Class UID and by the Enumerated Value of the mandatory Attribute in the DX Series Module, Presentation Intent Type (0008,0068).

### A.26.2 DX Image IOD Entity-Relationship Model

The E-R Model in Section A.1.2 depicts those components of the DICOM Information Model that directly reference the DX Image IOD.

### A.26.3 DX Image IOD Module Table

Table A.26-1. Digital X-Ray Image IOD Modules

IE | Module | Reference | Usage
--- | --- | --- | ---
Patient | Patient | C.7.1.1 | M
Clinical Trial Subject | C.7.1.3 | U
Study | General Study | C.7.2.1 | M
Patient Study | C.7.2.2 | U
Clinical Trial Study | C.7.2.3 | U
Series | General Series | C.7.3.1 | M
Clinical Trial Series | C.7.3.2 | U
DX Series | C.8.11.1 | M
Frame of Reference | Frame of Reference | C.7.4.1 | U
Equipment | General Equipment | C.7.5.1 | M
Image | General Image | C.7.6.1 | M
Image Pixel | C.7.6.3 | M
Contrast/Bolus | C.7.6.4 | U
Display Shutter | C.7.6.11 | U
Device | C.7.6.12 | U
Intervention | C.7.6.13 | U
Specimen | C.7.6.22 | U
DX Anatomy Imaged | C.8.11.2 | M
DX Image | C.8.11.3 | M
DX Detector | C.8.11.4 | M
X-Ray Collimator | C.8.7.3 | U
DX Positioning | C.8.11.5 | U
X-Ray Tomo Acquisition | C.8.7.7 | U
X-Ray Acquisition Dose | C.8.7.8 | U
X-Ray Generation | C.8.7.9 | U
X-Ray Filtration | C.8.7.10 | U
X-Ray Grid | C.8.7.11 | U
Overlay Plane | C.9.2 | C - Required if graphic annotation is present - See Section A.26.4
VOI LUT | C.11.2 | C - Required if Presentation Intent Type (0008,0068) is FOR PRESENTATION. Shall not be present otherwise. See Note 8.
Image Histogram | C.11.5 | U
Acquisition Context | C.7.6.14 | M - See Section A.26.5
SOP Common | C.12.1 | M
Common Instance Reference | C.12.2 | U

### Note

1. The Overlay Plane requirement is determined by the presence of "graphic annotation". Graphic annotation includes user or machine drawn graphics or text (such as computer assisted diagnosis) to indicate regions of interest or descriptions. It specifically does not include patient or image identification or technique information that is defined in other Attributes of the IOD.

2. The Device and Intervention Modules are User optional, though it is desirable that, if present, they are stored by an SCP. It is recognized that in some cases the digital image acquisition system will not have a user interface or direct connection that allows acquisition of these parameters, even if device or therapy have been used.

3. The Frame of Reference, X-Ray Collimator, DX Positioning and DX Tomo Acquisition Modules are User optional, though it is desirable that, if present, they are stored by an SCP. It is recognized that in some cases the parameters of the mechanical devices used for collimation, positioning and tomography may not be available to a digital image acquisition system that is not integrated with the X-Ray generation and positioning system.

4. The Histogram Module may contain a single or multiple statistical representations of the pixel data used to derive the VOI LUT Module, or intended to be used to derive or replace the VOI LUT Module. The Histogram Module may contain statistics of a subset of the stored image pixel data (such as from a cropped area or region of interest that is not the full field of view) that are useful for deriving a better VOI LUT than might be derived from the statistics obtained from the entire stored pixel data.

5. The Specimen Identification Module was previously included in this IOD but has been retired, and its functionality replaced by the Specimen Module. See PS3.3-2008.

6. The VOI LUT Module Attributes and behavior are further specialized in the DX Image Module.

7. The Curve Module was previously included in this IOD but has been retired. See PS3.3-2004.

### A.26.4 Overlay Plane Module

If the Overlay Plane Module is present, any Overlays defined in that Module shall store the overlay data in Overlay Data (60xx,3000), and not any unused high bits in Pixel Data (7FE0,0010).

### A.26.5 Acquisition Context Module

The Acquisition Context Module may be used to encode information about conditions present during acquisition that are not described by specific attributes in other modules of the IOD.

The Baseline TID shall be TID 3460 “Projection Radiography Acquisition Context”.

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