FFF.2.1.3.2.4 Example

In this example, the patient is on the table in position “Head First Supine”. The table is tilted of -10 degrees, with the head of the patient below the feet, and the image detector is parallel to the tabletop plane. The table cradle and rotation angles are equal to zero.

The image acquisition is performed during a movement of the X-Ray Table in the tabletop plane, at constant speed and of one meter of distance, acquiring frames from the abdomen to the feet of the patient in one stepping movement for non-subtracted angiography.

The table is related to the C-arm positioner so that the coordinates of the table position are known in the isocenter reference system. This allows determining the projection magnification of the table top plane with respect to the detector plane.

[pic]

Figure FFF.2.1-16Table Trajectory during T able Stepping

[pic]

Figure FFF.2.1-17Example of table positions per-frame during table stepping

Below are the encoded values of the key attributes of this example:

Positioner Type (0018,1508) = CARM
C-arm Positioner Tabletop Relationship (0018,9474) = YES
Per-Frame Functional Groups Sequence (5200,9230)  
  Item 1   Frame 1
    >Table Position Sequence (0018,9406)  
      Item 1    
        >>Table Top Vertical Position (300A,0128)
      Item 1    
        >>Table X Position to Isocenter (0018,9466)
  Item "N"   Frame "N"
    >Table Position Sequence (0018,9406)  
      Item 1    
        >>Table Top Vertical Position (300A,0128)
      Item 1    
     
X-Ray Exposure Control Sensing Regions C.8.19.6.3 Specifies the shape and size of the sensing regions in pixels, as well as their position relative to the top left pixel of the image.

FFF.2.1.4.1.3.1 X-Ray Exposure Control Sensing Regions Macro Recommendations

This macro is recommended to encode details about sensing regions.

If the position of the sensing regions is fixed during the multi-frame acquisition, the usage of this macro is shared.

If the position of the sensing regions was changed during the multi-frame acquisition, this macro is encoded per-frame to reflect the individual positions.

The same number of regions is typically used for all the frames of the image. However it is technically possible to activate or deactivate some of the regions during a given range of frames, in which case this macro is encoded per-frame.

Table FFF.2.1-39 X-RAY EXPOSURE CONTROL SENSING REGIONS MACRO Recommendations

Attribute Name Tag Comment
Exposure Control Sensing Regions Sequence (0018,9434) As many items as number of regions.