DICOM WG-02

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DICOM WG-02 Advances in X-Ray Angiography
Projection Imaging and 3D SPIE Medical
Imaging 2009, Orlando
Authors Tim Becker European Society of
Cardiology Heinz Blendinger Siemens
Healthcare Bas Revet Philips Healthcare
Francisco Sureda GE Healthcare (Speaker)
Rainer Thieme Siemens Medical Solutions (Chair
DICOM WG-02)
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Presentation Outline

• Introduction
• Present and future of X-Ray Angiography in DICOM
• 2D Projection Images Presentation
• Application Cases of the Enhanced XA SOP Class
• XA 2D Grayscale Softcopy Presentation State
• 3D Reconstruction from Projections Presentation
• X-Ray 3D SOP Class
• N-Dimensional Grayscale Softcopy Presentation
  State
• Conclusion

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Overview of X-Ray Angiography in DICOM
Approved in the Standard
Work in Progress
X-Ray Acquisition
Follow-up of PAS by IEC MT38 62B
Supp 94 Radiation Dose Reporting
Follow-up of IHE REM Profile
2D Projection Images
Supp 139-PC Enhanced XA Informative Annex
Supp 83 Enhanced XA/XRF
Supp 140-PC Presentation State
3D Reconstruction
Supp 116 X-Ray 3D Storage
Multi-Dimensional Presentation State
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Workflow 2D X-Ray Angiography
2D Visualization System
X-Ray Acquisition System
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Enhanced XA 2D projection images

• Supplement 83 Standard 2004
• New SOP Class for Multi-frame X-Ray Projection
  Angiography
• Re-use of encoding mechanisms of Enhanced CT and
  MR
• Enhanced with new attributes to support new
  applications
• What can be done with this new SOP Class?
• Supplement 139 (Part 17 Informative) Public
  Comments passed
• Describes use cases where the Enhanced XA
  provides better solutions
• Provides encoding guidelines for implementors,
  both creators and users of the Enhanced XA SOP
  Class

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Enhanced XA Supplement 139

• General Definitions
• Time relationships, Acquisition Geometry, Pixel
  Size calibration
• Application Use Cases
• Acquisition Waveform synch, Mechanical
  Movement, X-Ray controls
• Image Registration 3D structures projected on
  2D images
• Display Standard pipeline, multi-mask
  subtraction, per-frame pixel shift
• Review Variable review settings per group of
  frames
• Processing Projection pixel calibration

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Enhanced XA Time Relationships
Frame i Acquisition Datetime
Frame N Acquisition Datetime
Frame 1 Acquisition Datetime (0018,9074)
Content Date (0008,0023) Content Time (0008,0033)
Frame 1 Reference Datetime (0018,9151)
Acquisition Datetime (0008,002A)
Frame N Reference Datetime
Frame i Reference Datetime


time
FRAME 1
FRAME i
FRAME N
Frame 1 Acquisition Duration (0018,9220)
Frame N Acquisition Duration
Acquisition Duration (calculated)
If Acquisition is synchronized with external time
reference then Acquisition Time Synchronized
(0018,1800) YES
Exposure Time (0018,9328) SUMi( Frame i
Acquisition Duration ) Average Pulse Width
(0018,1154) SUMi(Frame i Acquisition
Duration) / N
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Enhanced XA Time Relationships (one frame)
Frame Reference Datetime (0018,9151)
Frame Acquisition Datetime (0018,9074)
X-ray FRAME i Frame Acquisition Number
(0020,9156) i
PRE-FRAME X-ray
time
Detector Activation Offset from Exposure
(0018,7016)
Frame Acquisition Duration (0018,9220)
R
Detector Active Time (0018,7014)
Cardiac Trigger Delay Time (0020,9153)
Last R-peak prior to the X-ray FRAME i
T
Q
S
NOTE Positioner angle values, table position
values etc are measured at the Frame Reference
Datetime
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Enhanced XA Acquisition Techniques

• Values per frame are in the Per-frame Functional
  Groups Seq. (200,9230)
• In the Frame Content Sequence (0020,9111)
• Frame Acquisition Duration (0018,9220) in ms of
  frame  i  Dti
• In the Frame Acquisition Sequence
  (0018,9417)
• KVP (0018,0060) of frame  i  kVpi
• X-Ray Tube Current in mA (0018,9330) of frame
   i  mAi

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Enhanced XA Acquisition Geometry
System set up
Image Transformation
X-Ray Acquisition
Pixel Data Storage
PATIENT position on the Table
FOV Rotation Horiz Flip
TABLE movement
POSITIONER movement
Detector Binning
Patient Position Description
X-Ray Table Description
X-Ray Positioner Description
FOV Description
Detector Description

• ? X-Ray Field of View Macro
• ? XA/XRF Acquisition Module
• X-Ray Detector Module
• Image Pixel Module

• ? X-Ray Isocenter Reference System Macro
• ? X-Ray Geometry Macro

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Enhanced XA 3D/2D Registration


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Enhanced XA Standard Display Pipeline
Shape IDENTITY if (0028,0004) MONOCHROME2
Shape INVERSE if (0028,0004) MONOCHROME1
X
Modality LUT
TO_LINEAR is required if Pixel Intensity
Relationship (0028,1040) LOG
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Enhanced XA Variable Review Settings
FRAME ACQUISITION
Frame Display Sequence (0018,7022)
DICOM ENCODING XA/XRF Multi-frame Presentation
Module
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Enhanced XA Pixel Shift per frame
DICOM ENCODING Mask Module
FRAME ACQUISITION and PROCESSING
Frames
Mask Subtraction Sequence (0028,6100)
1
2
3
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Enhanced XA Pixel Shift per frame
DICOM ENCODING Frame Pixel Shift per frame
FRAME ACQUISITION and PROCESSING
Frames
Item 2
Frame 2
gtFrame Pixel Shift Seq (0028,9415)
1
2
Item 3
Frame 3
gtFrame Pixel Shift Seq (0028,9415)
3
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Enhanced XA Pixel Shift per frame
DICOM ENCODING Frame Pixel Shift per frame
FRAME ACQUISITION and PROCESSING
Frames
Item 2
Frame 2
gtFrame Pixel Shift Seq (0028,9415)
1
2
Item 3
Frame 3
gtFrame Pixel Shift Seq (0028,9415)
3
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Enhanced XA Pixel Shift per frame
DICOM ENCODING Frame Pixel Shift per frame
FRAME ACQUISITION and PROCESSING
Frames
Item 2
Frame 2
gtFrame Pixel Shift Seq (0028,9415)
1
2
Item 3
Frame 3
gtFrame Pixel Shift Seq (0028,9415)
3
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Enhanced XA - Projection Pixel Size Calibration
How to convert from image pixels to object mm
in patient

• Px Object size in image pixels
• D Object size in mm
• TH Table Height (0018,1130)
• TO Dist. Table to Object (0018,9403)
• Beam Angle (0018,9449)
• SID Dist. Source-Detector (0018,1110)
• ISO Dist. Source-ISO (0018,9402)
• DPx Imager Pixel Spacing (0018,1164)

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XA/XRF Projection Presentation State
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Supplement 140 new XA GSPS IOD (for 2D)
Information that may be used to present
angiographic projection images It includes
capabilities from the Grayscale Softcopy
Presentation IOD for specifying a. the output
grayscale space in P-Values b. grayscale
contrast transformations including VOI LUT c.
selection of the area of the image to display ,
rotate, flip d. image and display relative
annotations, graphics, text and overlays
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Supplement 140 new XA GSPS IOD (for 2D)
Specific capabilities are provided for the
presentation of angiographic projection
images a. shutter specifications on a
frame-by-frame base, b. mask subtraction
including regional pixel shift c. presentation
of sets of frames Similar to the XA/XRF
Multi-Frame Presentation Module of the Enhanced
XA/XRF
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XA Grayscale Softcopy Presentation State

• Grayscale Contrast Transformations
• The sequence of transformations from stored pixel
  values into P-Values is explicitly defined in a
  conceptual model

• Shutter per frame
• The shutter coordinates per-frame may be modified
  in post-review

Frame 1
Frame 2
Frame 3
Frame 4
Frame 5
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XA Grayscale Softcopy Presentation State
? mask subtraction regional pixel shift
If Pixel Intensity Relationship is not LOG
 TO_LOG  LUT

Else
SUB
VOI LUT
Contrast Frame(s)
Pixel Shift Anatomic Background Visibility
Else
 TO_LOG  LUT
If Pixel Intensity Relationship is not LOG
Mask Frame(s)
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XA Grayscale Softcopy Presentation State
? Regional pixel shift
Applicable pixel shift in case of multiple pixel
shift regions
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Sup 140 Example of Regional Pixel Shift
Mask frame non-injected structures (bones,
soft-tissues)
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Sup 140 Example of Regional Pixel Shift
Contrast frame injected vessels background
structures moved since the mask acquisition
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Sup 140 Example of Regional Pixel Shift
Subtraction without pixel shift background
structures are visible
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Sup 140 Example of Regional Pixel Shift
Regional Pixel Shift Select region 1
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Sup 140 Example of Regional Pixel Shift
Mask Pixel Shift (Column)
Mask Pixel Shift (Row)
Regional Pixel Shift Apply shift to mask on
region 1
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Sup 140 Example of Regional Pixel Shift
Mask Pixel Shift (Column)
Mask Pixel Shift (Row)
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Sup 140 Example of Regional Pixel Shift
Mask Pixel Shift (Column)
Mask Pixel Shift (Row)
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Sup 140 Example of Regional Pixel Shift
Mask Pixel Shift (Column)
Mask Pixel Shift (Row)
until background structures are not visible
anymore
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Sup 140 Example of Regional Pixel Shift
Regional Pixel Shift Select region 2
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Sup 140 Example of Regional Pixel Shift
Mask Pixel Shift (Column)
Regional Pixel Shift Apply shift to mask on
region 2
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Sup 140 Example of Regional Pixel Shift
Regional Pixel Shift Select region 3
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Sup 140 Example of Regional Pixel Shift
Mask Pixel Shift (Column)
Regional Pixel Shift Apply shift to mask on
region 3
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Sup 140 Example of Regional Pixel Shift
Subtraction with regional pixel shift background
structures are not visible anymore
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3D X-Ray Angiography
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Workflow 3D X-Ray Angiography
3D Reconstruction System
X-Ray Acquisition System
3D Visualization System
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X-Ray 3D Angiography

• Supplement 116 In standard 2007
• New SOP Class for Multi-frame X-Ray 3D from
  projections
• Re-use of encoding mechanisms of Enhanced CT and
  MR
• Re-use volumic descriptions of Enhanced CT and MR
• Additional information of the reconstruction from
  projections
• What can be done with this new SOP Class?
• Basic 3D visualization (slices)
• References to 2D projections
• Description of the reconstruction application
• Relationship to the Equipment Coordinate System
• ...

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X-Ray 3D Angiography Rotational Acquisition
Frame 5 X-ray settings 5 Geometry settings 5
Frame 4 X-ray settings 4 Geometry settings 4
Frame 3 X-ray settings 3 Geometry settings 3
Frame 2 X-ray settings 2 Geometry settings 2
Frame 1 X-ray settings 1 Geometry settings 1
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X-Ray 3D Angiography Reference to 2D
2D Projection SOP Instance A
Contributing Sources Sequence (0018,9506) SOP
Instance description
X-Ray 3D Acquisition Sequence (0018,9507) Acqui
sition description
X-Ray 3D Reconstruction Sequence
(0018,9530) Reconstruction description
Per-Frame Func Groups Sequence
(5200,9230) Frame description
X-Ray 3D SOP Instance
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X-Ray 3D Angiography - Relationship to Equipment
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X-Ray 3D Angiography Presentation State
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X-Ray 3D Angiography Presentation State

• Needs for 3D Angiography Presentation
• Presentation features common to all 3D
• Speficic presentation of X-Ray 3D Angiography
• Acquisition 3D shutter for collimation
• Volume Subtraction and voxel shift
• Stabilized point in all volumes (e.g. cardiac
  wall motion, stent stabilized)
• Catheter tracking trajectory in one volume
• 2D-3D blending presentation (3D conic projection
  on 2D fluoroscopy)
• N-Dimensional Presentation State
• Work Item 2008-04-C. Addresses needs of
  multi-modalities
• Led by Working Group 11, participation of Web3D
  and other working groups
• Supplement in progress...

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Conclusion

• Supplement 139 Enhanced XA application cases
• In Public Comments. Informative (DICOM Part 17)
• Will facilitate the adoption of the Enhanced XA
  (Sup 83)
• Supplement 140 XA/XRF Presentation State
• In Public Comments. Enables
• shutter on a frame-by-frame base,
• mask subtraction including regional pixel shift
• presentation of set of frames
• X-Ray 3D Angiography
• New IOD approved in Standard 2007 (Sup 116)
• 3D Presentation State on-going...

Contact WG-02 chairman francisco.sureda_at_med.ge.co
m