DICOM PS3.17 2018b - Explanatory Information

TTT.2.5.3.2 X-Ray 3D Angiographic Image IOD
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##### TTT.2.5.3.2 X-Ray 3D Angiographic Image IOD

###### TTT.2.5.3.2.1 Image Pixel Module Recommendations

This module encodes the description of the pixels of the slices of the volumes, each slice being one frame of the X-Ray 3D Angiographic instance. The pixel data encodes all the frames of the first cardiac phase followed by all the frames of the second cardiac phase and so on. Within one cardiac phase, the order of the frames is aligned with the Image Position (Patient) attribute.

###### TTT.2.5.3.2.2 Multi-frame Dimension Module Recommendations

This module encodes the dimensions for the presentation order of the image frames.

Table TTT.2.5-1. Multi-frame Dimension Module Recommendations

Attribute Name | Tag | Recommendation
--- | --- | ---
Dimension Organization Sequence | (0020,9221) | There will be a single Dimension UID.
Dimension Organization Type | (0020,9311) | The value will be "3D".
Dimension Index Sequence | (0020,9222) | Two items are defined: the first one related to the cardiac phase, the second one related to the spatial position of the slices. All frames of the same reconstructed volume have the same cardiac phase.
>Dimension Index Pointer | (0020,9165) | In the first item, the attribute Nominal Percentage of Cardiac Phase (0020,9241) is used. In the second item, the attribute Image Position (Patient) (0020,0032) is used.
>Functional Group Pointer | (0020,9167) | Contains the tags (0018,9118) Cardiac Synchronization Sequence and (0020,9113) Plane Position Sequence respectively in the first and second item.
>Dimension Organization UID | (0020,9164) | Same value for both items.

###### TTT.2.5.3.2.3 X-Ray 3D Angiographic Acquisition Module Recommendations

There are multiple acquisition contexts, one per cardiac phase. This module encodes the frame numbers of the source SOP instance that belong to each acquisition context and have the same cardiac phase.

Table TTT.2.5-2. X-Ray 3D Angiographic Acquisition Module Recommendations

Attribute Name | Tag | Recommendation
--- | --- | ---
X-Ray 3D Acquisition Sequence | (0018,9507) | One item for each acquisition context (i.e., each cardiac phase).
>Source Image Sequence | (0008,2112) |
>>Referenced Frame Number | (0008,1160) | The frame numbers of the source SOP instance that belong to this acquisition context (i.e., that have the same cardiac phase). ### Note The number of projection frames may be different for each acquisition context. See Note 2 of Section TTT.2.5.2.

###### TTT.2.5.3.2.4 X-Ray 3D Reconstruction Module Recommendations

This module encodes the identification of the reconstructions performed to create the X-Ray 3D Angiographic Instance.

Table TTT.2.5-3. X-Ray 3D Reconstruction Module Recommendations

Attribute Name | Tag | Recommendation
--- | --- | ---
X-Ray 3D Reconstruction Sequence | (0018,9530) | One item for each single reconstruction, i.e., for each cardiac phase.
>Acquisition Index | (0020,9518) | Number of the acquisition context for this reconstruction. As there is one reconstruction for each cardiac phase, the acquisition index is equal to the reconstruction index.
>Reconstruction Description | (0018,9531) | Free text description of the purpose of the reconstruction. It's recommended to identify the cardiac phase.

###### TTT.2.5.3.2.5 Frame Content Macro Recommendations

This module encodes the timing information of the frames, as well as dimension and stack index values. All frames forming a volume of one cardiac phase have the same time reference, and a single dimension index value for the first dimension. All volumes for all cardiac phases share the same stack id because they span the same space.

Table TTT.2.5-4. Frame Content Macro Recommendations

Attribute Name | Tag | Recommendation
--- | --- | ---
Frame Content Sequence | (0020,9111) |
>Frame Reference DateTime | (0018,9151) | Use the date and time of the first 2D frame used for the reconstruction of this 3D frame. In practice it will be the time of the first projection of this cardiac phase.
>Frame Acquisition DateTime | (0018,9074) | Use the same value as the Frame Reference DateTime (0018,9151).
>Frame Acquisition Duration | (0018,9220) | Use the elapsed time from the first to the last projection frame time used for the reconstruction of this 3D frame.
>Cardiac Cycle Position | (0018,9236) | Use the most representative position in the cardiac cycle.
>Dimension Index Values | (0020,9157) | The first value of this attribute contains the same index for all the frames of the same volume (i.e., same cardiac phase). The second value indexes the spatial position of each frame in the volume.
>Stack ID | (0020,9056) | Same ID for all the frames of all cardiac phases.
>In-Stack Position Number | (0020,9057) | From 1 to M for each cardiac phase, where M is the number of frames in each reconstructed phase. The spatially corresponding frames in different cardiac phases share the same In-Stack Position Number.

###### TTT.2.5.3.2.6 Cardiac Synchronization Macro Recommendations

This module encodes a value representing the cardiac phase of the 3D frames (i.e., the time of the frame relative to the R-peak).

Table TTT.2.5-5. Cardiac Synchronization Macro Recommendations

Attribute Name | Tag | Recommendation
--- | --- | ---
Cardiac Synchronization Sequence | (0018,9118) |
>Nominal Percentage of Cardiac Phase | (0020,9241) | All the frames belonging to the same reconstruction will have the same value. This attribute is used as a dimension index.
>Nominal Cardiac Trigger Delay Time | (0020,9153) | Use the average time in ms from the time of the previous R-peak to the value of the Frame Reference DateTime (0018,9151).

###### TTT.2.5.3.2.7 X-Ray 3D Frame Type Macro Recommendations

This macro encodes the context of the volume slices. In this scenario of multi-volume encoding, it is encoded "per frame", since the slices belong to different volumes depending on the cardiac phase.

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DICOM PS3.17 2018b - Explanatory Information