DICOM PS3.3 2021b - Information Object Definitions

C.8.19.6.4 X-Ray Frame Pixel Data Properties Macro (Current)
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##### C.8.19.6.4 X-Ray Frame Pixel Data Properties Macro

Table C.8.19.6-4 specifies the Attributes of the X-Ray Frame Pixel Data Properties Functional Group Macro.

Table C.8.19.6-4. X-Ray Frame Pixel Data Properties Macro Attributes

Attribute Name | Tag | Type | Attribute Description
--- | --- | --- | ---
Frame Pixel Data Properties Sequence | (0028,9443) | 1 | Sequence containing the pixel data properties for this frame. Only a single Item shall be included in this Sequence.
>Frame Type | (0008,9007) | 1 | Type of Frame. A multi-valued Attribute analogous to Image Type (0008,0008). Enumerated Values and Defined Terms are the same as those for the values of Image Type (0008,0008). See Section C.8.19.2.1.1.
>Pixel Intensity Relationship | (0028,1040) | 1 | The relationship between the Pixel and the X-Ray beam intensity. See Section C.8.19.6.4.1.1.
>Pixel Intensity Relationship Sign | (0028,1041) | 1 | The sign of the relationship between the Pixel sample values stored in Pixel Data (7FE0,0010) and the X-Ray beam intensity. Enumerated Values: +1 Lower pixel values correspond to less X-Ray beam intensity -1 Higher pixel values correspond to less X-Ray beam intensity See Section C.8.11.3.1.2 for further explanation.
>Imager Pixel Spacing | (0018,1164) | 1C | Physical distance measured at the receptor plane of the detector between the centers of each pixel specified by a numeric pair - row spacing value (delimiter) column spacing value in mm. See Section 10.7.1.3 for further explanation of the value order. The value of this Attribute shall never be adjusted to account for calibration against an object of known size; Pixel Spacing (0028,0030) is specified for that purpose. It is only allowed to be adjusted to compensate for the change of the Field of View Dimension(s) in Float (0018,9461) Attribute. See Section C.8.19.6.4.1.2 Required if Image Type (0008,0008) Value 1 equals ORIGINAL. May be present otherwise. ### Note These values are the actual pixel spacing distances of the stored pixel values of an image.
>Pixel Data Area Origin Relative To FOV | (0018,7036) | 3 | Offset of the TLHC of the image stored in Pixel Data (7FE0,0010) from the TLHC of the Field Of View Area after FOV rotation and Flip. It is measured in image stored pixels as a row offset followed by a column offset. ### Note Due to the differences in image stored pixel and detector element spacing, one may expect this Attribute to have non-integer values. See Section C.8.19.6.4.1.3.
>Pixel Data Area Rotation Angle Relative To FOV | (0018,7038) | 3 | Angle clockwise of the row direction of the image stored in Pixel Data (7FE0,0010) relative to the row direction of the Field Of View Area after FOV rotation and Flip. It is measured in degrees. See Section C.8.19.6.4.1.3.
>Geometrical Properties | (0028,9444) | 1 | Geometrical characteristics of the pixel data to indicate whether pixel spacing is uniform for all pixels or not. Enumerated Values: UNIFORM NON_UNIFORM
>Geometric Maximum Distortion | (0028,9445) | 2C | The percentage of the maximum deviation of the pixel spacing values of images for which the geometric properties are non-uniform. ### Note This Attribute may be used to judge the result of measurements, 3D reconstructions, etc. Required if Geometrical Properties (0028,9444) equals NON_UNIFORM.
>Image Processing Applied | (0028,9446) | 1 | The type or a combination of types of image processing applied to the pixel data before being stored. Defined Terms: DIGITAL_SUBTR HIGH_PASS_FILTER LOW_PASS_FILTER MULTI_BAND_FLTR FRAME_AVERAGING NONE

###### C.8.19.6.4.1 X-Ray Frame Pixel Data Properties Attributes

###### C.8.19.6.4.1.1 Pixel Intensity Relationship

Pixel Intensity Relationship (0028,1040) shall identify the relationship of the pixel values to the X-Ray beam intensity.

Defined Terms:

LIN

  Approximately proportional to X-Ray beam intensity.

LOG

  Non-linear "Log Function"; A Pixel Intensity Relationship LUT shall be included with the image to allow it to be mapped back to its proportional value to X-Ray beam intensity.

OTHER

  Not proportional to X-Ray beam intensity. If a TO_LINEAR Pixel Intensity Relationship LUT Item is supplied, scaling back to X-Ray beam intensity is possible.

### Note

1. When the relationship can be better defined (e.g., square root data) a more precise Defined Term can be used than OTHER.

2. Providing a TO_LINEAR Pixel Intensity Relationship LUT is encouraged.

###### C.8.19.6.4.1.2 Imager Pixel Spacing

The two values of the Imager Pixel Spacing (0018,1164) Attribute are related to the value(s) of the Field of View Dimension(s) in Float (0018,9461) Attribute in the X-Ray Field of View Functional Group of this frame and the values of the Rows (0028,0010) and Columns (0028,0011) Attributes.

The value(s) of Field of View Dimension(s) in Float (0018,9461) may change on a frame by frame base. The values of the Rows and Columns Attributes are equal for all frames. The relationship between the Attributes depends on the Field of View Shape (0018,1147) Attribute:

If the Field of View Shape (0018,1147) Attribute equals RECTANGLE:

Imager Pixel Spacingrow spacing = FOV Dimensionrow dimension / Rows

Imager Pixel Spacingcolumn spacing = FOV Dimensioncolumn dimension / Columns

If the Field of View Shape (0018,1147) Attribute equals ROUND or HEXAGONAL:

Imager Pixel Spacingrow spacing = FOV Dimensiondiameter / Rows

Imager Pixel Spacingcolumn spacing = FOV Dimensiondiameter / Columns

###### C.8.19.6.4.1.3 Pixel Data Area Relative to FOV

In the case where the Field of View does not have the same size as the stored Pixel Data (7FE0,0010), the stored Pixel Data (7FE0,0010) may be the result of cropping, rotation, resizing and/or padding of the Field of View. The following Attributes specify the relationship of the Pixel Data area to the Field Of View Area:

- Pixel Data Area Origin Relative to FOV (0018,7036)

- Pixel Data Area Rotation Angle Relative to FOV (0018,7038)

### Note

In order to make use of the Pixel Data Area Origin Relative to FOV (0018,7036), the Imager Pixel Spacing (0018,1164) is needed.

Figure C.8.19.6.4-1. Explanation of Pixel Data Area Attributes

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DICOM PS3.3 2021b - Information Object Definitions