Материал: part17

TTT.2.4.3.2.3 Frame Content Macro Recommendations​

This module encodes the timing information of the frames, as well as dimension and stack index values.​

Table TTT.2.4-4. Frame Content Macro Recommendations​

TTT.2.4.4 Example​

Thisexampleisthereconstructionofavolumebyaback-projectionfromallframesofarotationalacquisitionwithtworotationsencoded​ as two XA Images.​

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Figure TTT.2.4-3. Attributes of 3D Reconstruction using multiple rotation images​

TTT.2.5 Case #5: One Rotation, One 2D Instance, Multiple Reconstructions, One X-Ray 3D​ Instance​

This application case is related to a rotational acquisition of several cardiac cycles with related ECG signal information.​

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TTT.2.5.1 User Scenario​

The image acquisition system performs one 2D rotational acquisition of the heart in a cardiac procedure. The gantry is continuously​ rotating at a constant speed. The ECG is recorded during the rotation, and the cardiac trigger delay time is known for each frame of​ the rotational acquisition allowing it to be assigned to a given cardiac phase.​

Several 3D volumes are reconstructed, one for each cardiac phase.​

TTT.2.5.2 Encoding Outline​

The rotational acquisition can either be encoded as XA Image or as Enhanced XA Image. The XA instance (let's call it "C") is encoded​

in the Series "B" of the Study "A".​

Eachreconstructionisrelatedtoonecardiacphasecorrespondingtoasub-setofframesoftherotationalacquisition.Therefore,each​ cardiac phase represents one acquisition context.​

Each reconstruction leads to one volume, all volumes are encoded in one single X-Ray 3D Angiographic instance ("Z"). Each volume​ is for a different cardiac phase. All volumes share the same stack id.​

Figure TTT.2.5-1. Encoding of various 3D reconstructions at different cardiac phases​

Note​

1.​Thisfigureshowsonlythefirstthreecardiacphases.Animplementationmaychosehowmanyphasesitwillreconstruct.​

2.​Projection frames are assigned to a phase based on their cardiac trigger delay time. The rotation speed and acquisition​ pulseratewillnotnecessarilyalignuniformlywiththecardiaccycle(especiallyiftheheartbeatisirregular).Thusdifferent​ phases may end up with different number of projections assigned to them. The reconstructed volumes will have the​ same space.​

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TTT.2.5.3 Encoding Details​

TTT.2.5.3.1 2D X-Ray Angiographic Image IOD​

This scenario is based on the encoding of a single rotational acquisition in one 2D instance, together with the information of the ECG​ and/or the cardiac trigger delay times of each frame of the rotational image.​

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

TTT.2.5.3.2.1 Image Pixel Module Recommendations​

Thismoduleencodesthedescriptionofthepixelsoftheslicesofthevolumes,eachslicebeingoneframeoftheX-Ray3DAngiographic​ 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​

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​

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.​

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Page 700​ DICOM PS3.17 2020a - Explanatory Information​

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

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​

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​

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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