C.8.19.6.3 X-Ray Exposure Control Sensing Regions Macro
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##### C.8.19.6.3 X-Ray Exposure Control Sensing Regions Macro

Table C.8.19.6-3 specifies the attributes that describe the region targeted as area where the x-ray dose value is estimated.

Table C.8.19.6-3. X-Ray Exposure Control Sensing Regions Macro Attributes

Attribute Name | Tag | Type | Attribute Description
--- | --- | --- | ---
Exposure Control Sensing Regions Sequence | (0018,9434) | 1 | Sequence containing the Exposure Control Sensing Region for this frame. One or more items shall be included in this sequence.
>Exposure Control Sensing Region Shape | (0018,9435) | 1 | Shape of the Exposure Control Sensing Region. Enumerated Values: RECTANGULAR CIRCULAR POLYGONAL
>Exposure Control Sensing Region Left Vertical Edge | (0018,9436) | 1C | Required if Exposure Control Sensing Region Shape (0018,9435) is RECTANGULAR. Location of the left edge of the rectangular Exposure Control Sensing Region expressed as effective pixel column. See Section C.8.19.6.3.1.
>Exposure Control Sensing Region Right Vertical Edge | (0018,9437) | 1C | Required if Exposure Control Sensing Region Shape (0018,9435) is RECTANGULAR. Location of the right edge of the rectangular Exposure Control Sensing Region expressed as effective pixel column. See Section C.8.19.6.3.1.
>Exposure Control Sensing Region Upper Horizontal Edge | (0018,9438) | 1C | Required if Exposure Control Sensing Region Shape (0018,9435) is RECTANGULAR. Location of the upper edge of the rectangular Exposure Control Sensing Region expressed as effective pixel row. See Section C.8.19.6.3.1.
>Exposure Control Sensing Region Lower Horizontal Edge | (0018,9439) | 1C | Required if Exposure Control Sensing Region Shape (0018,9435) is RECTANGULAR. Location of the lower edge of the rectangular Exposure Control Sensing Region expressed as effective pixel row. See Section C.8.19.6.3.1.
>Center of Circular Exposure Control Sensing Region | (0018,9440) | 1C | Required if Exposure Control Sensing Region Shape (0018,9435) is CIRCULAR. Location of the center of the circular Exposure Control Sensing Region expressed as effective pixel row and column. See Section C.8.19.6.3.1.
>Radius of Circular Exposure Control Sensing Region | (0018,9441) | 1C | Required if Exposure Control Sensing Region Shape (0018,9435) is CIRCULAR. Radius of the circular Exposure Control Sensing Region expressed as effective number of pixels along the row direction. See Section C.8.19.6.3.1.
>Vertices of the Polygonal Exposure Control Sensing Region | (0018,9442) | 1C | Required if Exposure Control Sensing Region Shape (0018,9435) is POLYGONAL. Multiple Values where the first set of two values are: row of the origin vertex; column of the origin vertex. Two or more pairs of values follow and are the effective pixel row and column coordinates of the other vertices of the polygon Exposure Control Sensing Region. Polygon Exposure Control Sensing Regions are implicitly closed from the last vertex to the origin vertex and all edges shall be non-intersecting except at the vertices. See Section C.8.19.6.3.1.

###### C.8.19.6.3.1 X-Ray Exposure Control Sensing Regions Attributes

The Exposure Control Sensing Region Left Vertical Edge (0018,9436), Exposure Control Sensing Region Right Vertical Edge (0018,9437), Exposure Control Sensing Region Upper Horizontal Edge (0018,9438), Exposure Control Sensing Region Lower Horizontal Edge (0018,9439) and Center of Circular Exposure Control Sensing Region (0018,9440) may have a negative value when the point defined by the attribute lies outside the left or upper border of the pixel data matrix. The top left pixel of the image has a pixel row and column value of 1.

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