FFF.2.3.3.4 Examples

FFF.2.3.3.4.1 Usage of Pixel Shift Macro in Shared Context

In this example, the pixel shift –0.3\2.0 is applied to the frames 2 and 3 when they are subtracted to the mask frame 1 as defined in the Mask Subtraction Sequence.

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

Mask Subtraction Sequence (0028,6100)
Item 1
>Mask Operation (0028,6101) = AVG_SUB
>Subtraction Item ID (0028,9416) = 100
>Applicable Frame Range (0028,6102) = 2\3
>Mask Frame Numbers (0028,6110) = 1
>Mask Operation Explanation (0028,6190) = Default Subtraction
Shared Functional Group Sequence (5200,9229)
Item 1 All the frames
>Frame Pixel Shift Sequence (0028,9415)
Item 1
Item 1
>Mask Operation (0028,6101) = AVG_SUB
>Subtraction Item ID (0028,9416) = 100
>Applicable Frame Range (0028,6102) = 2\3
>Mask Frame Numbers (0028,6110) = 1
>Mask Operation Explanation (0028,6190) = Left Leg
Per-Frame Functional Groups Sequence (5200,9230)
Item 1 Frame 1
>Frame Pixel Shift Sequence (0028,9415)
Item 1
>Frame Pixel Shift Sequence (0028,9415)
Item 1
>Frame Pixel Shift Sequence (0028,9415)
Item 1
Item 1
>Mask Operation (0028,6101) = AVG_SUB
>Subtraction Item ID (0028,9416) = 100
>Applicable Frame Range (0028,6102) = 2\3
>Mask Frame Numbers (0028,6110) = 1
>Mask Operation Explanation (0028,6190) = Left Leg
Item 2
>Mask Operation (0028,6101) = AVG_SUB
>Subtraction Item ID (0028,9416) = 101
>Applicable Frame Range (0028,6102) = 2\3
>Mask Frame Numbers (0028,6110) = 1
>Mask Operation Explanation (0028,6190) = Right Leg
Per-Frame Functional Groups Sequence (5200,9230)
Item 1 Frame 1
>Frame Pixel Shift Sequence (0028,9415)
Item 1
>Frame Pixel Shift Sequence (0028,9415)
Item 1
>Frame Pixel Shift Sequence (0028,9415)
Item 1
Image XA/XRF Acquisition C.8.19.3 Specifies system characteristics relevant for this scenario.

Table FFF.2. 4-2 ENHANCED XA IMAGE FUNCTIONAL GROUP MACROS

Functional Group Macro PS 3.3 Reference Usage
XA/XRF Frame Pixel Data Properties C.8.19.6.4 Specifies the pixel spacing on the receptor plane.
X-Ray Projection Pixel Calibration C.8.19.6.9 Specifies the calibration-specific attributes.
X-Ray Geometry C.8.19.6.14 Specifies the distances of the conic projection.

FFF.2.4.1.3.1 XA/XRF Acquisition Module Recommendations

In order to check if a calibration is appropriate, certain values have to be set in the XA/XRF Acquisition Module.

Table FFF.2.4-3 XA/XRF ACQUISITION MODULE Recommendations

Attribute Name Tag Comment
X-Ray Receptor Type (0018,9420) Recommended in this scenario. The values IMG_INTENSIFIER or DIGITAL_DETECTOR can provide information about exactness of the image plane.
Positioner Type (0018,1508) Recommended in this scenario. The value of CARM is typically expected for equipment providing geometry information required for calibration.
C-arm Positioner Tabletop Relationship (0018,9474) A value of YES is recommended in this scenario, to allow use of related information for calibration because table and gantry are geometrically aligned.

FFF.2.4.1.3.2 XA/XRF Frame Pixel Data Properties Macro Recommendations

This macro is recommended to provide the Pixel Spacing in the receptor plane. Typically the Image Pixel Spacing is identical for all frames. Future acquisition system techniques may result in per frame individual values.

Table FFF.2.4-4 XA/XRF FRAME PIXEL DATA PROPERTIES MACRO Recommendations

Attribute Name Tag Comment
Frame Pixel Data Properties Sequence (0028,9443)
>Imager Pixel Spacing (0018,1164) Recommended for this scenario, regardless the type of receptor.

FFF.2.4.1.3.3 X-Ray Projection Pixel Calibration Macro Recommendations

This macro contains the core inputs and results of calibration.

When there is no movement of the gantry and table, the macro is typically used in shared functional group context.

The attribute Beam Angle (0018,9449) is supplementary for the purpose of calibration; it is derived from the Primary and Secondary Positioner Angles but is not intended to replace them as they provide information for other purposes.

Table FFF.2.4-5 X-RAY PROJECTION PIXEL CALIBRATION MACRO Recommendations

Attribute Name Tag Comment
Projection Pixel Calibration Sequence (0018,9401)
>Distance Object to Table Top (0018,9403) Recommended in this scenario.
>Object Pixel Spacing in Center of Beam (0018,9404) Recommended in this scenario. The value pair corresponds to the patient plane defined by the other parameters in this macro.
>Table Height (0018,1130) Recommended in this scenario.
>Beam Angle (0018,9449) Recommended in this scenario.

FFF.2.4.1.3.4 X-Ray Geometry Macro Recommendations

When there is no change of the geometry, the macro is used in shared functional group context.