C.8.19.6.4.1 XA/XRF 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 are:

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. Notes: 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 Spacing row spacing = FOV Dimension row dimension / Rows

Imager Pixel Spacing column spacing = FOV Dimension column dimension / Columns

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

Imager Pixel Spacing row spacing = FOV Dimension diameter / Rows

Imager Pixel Spacing column spacing = FOV Dimension diameter / 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.

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