Dimension Organization Type (0020,9311) specifies the general structure of the image. The concept of “multi-frame dimensions” as specified by the Dimension Index Sequence (0020,9222) and per-frame Dimension Index Values (0020,9157) shall be used to specify the relationships of frames within that general structure.
If Dimension Organization Type (0020,9311) has values of 3D or 3D_TEMPORAL, then the Dimension Index Sequence (0020,9222) shall have exactly three items, with the dimension values described in Table C.220.127.116.11-1.
Table C.18.104.22.168-1DIMENSION DEFINITION FOR US ACQUISITION 3D IMAGES
|Dimension Index Sequence||(0020,9222)|
|1st||>Dimension Index Pointer||(0020,9165)||Tag of attribute specifying temporal position of frames|
|>Functional Group Pointer||(0020,9167)||Tag of sequence containing above attribute|
|2nd||>Dimension Index Pointer||(0020,9165)||(0020,9301) Image Position (Volume)|
|>Functional Group Pointer||(0020,9167)||(0020,930E) Plane Position (Volume) Sequence|
|3rd||>Dimension Index Pointer||(0020,9165)||(0018,9808) Data Type|
|>Functional Group Pointer||(0020,9167)||(0018,9807) Image Data Type Sequence|
The Dimension Index Values (0020,9157) corresponding to these dimension variables positively associate frames with different Data Type values at the same spatial and temporal position. Figure C.22.214.171.124-1 illustrates the use of Dimensions to associate frames with temporal, spatial, and Data Type dimensions.
These Dimension values shall be used even if there is only one possible value for a Dimension.
Note: For example, if Dimension Organization Type (0020,9311) has the value 3D, the temporal position dimension is present and the dimension index of the temporal attribute is the same in every frame of the image. Similarly, if the Data Type attribute is in the Shared Functional Group and all frames in the object are of Data Type TISSUE_INTENSITY, the Data Type dimension is present and the dimension index of the Data Type dimension is the same in every frame of the image.
Each plane in the volume consists of one or more frames each with a distinct value of Data Type (0018,9808). The planes in the cartesian volume shall have equal inter-plane spacing, accomplished through values of Image Position (Volume) (0020,9301).
Each frame comprising a volume shall have the same value of the temporal dimension attribute. Any appropriate physiological event temporal attribute may be used to specify the temporal position. If there is no specific physiological event to which the temporal position of frames is referenced, then Temporal Position Time Offset (0020,930D) in the Temporal Position Sequence (0020,9310) may be used as the temporal dimension attribute. If all frames are at the same temporal position, any temporal attribute may be referenced.
Note: For example, the attribute specifying temporal position of frames may be any appropriate temporal attribute, such as Nominal Cardiac Trigger Delay Time (0020,9153) or Nominal Percentage of Cardiac Phase (0020,9241) in the Cardiac Synchronization Sequence (0018,9118) if the temporal position of frames is referenced to the cardiac R-wave, or Nominal Respiratory Trigger Delay Time (0020,9255) or Nominal Percentage of Respiratory Phase (0020,9245) in the Respiratory Synchonization Sequence (0020,9253) if the temporal position of frames is referenced to the latest inspiration maximum.
Figure C.126.96.36.199-1 Dimension Organization Type Frame Relationships