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DICOM WG-02 Advances in X-Ray Angiography Projection Imaging and 3D SPIE Medical Imaging

DICOM WG-02 Advances in X-Ray Angiography Projection Imaging and 3D SPIE Medical Imaging 2007, San Diego. Authors : Tim Becker European Society of Cardiology Heinz Blendinger Siemens Medical Solutions Bas Revet Philips Medical Systems

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DICOM WG-02 Advances in X-Ray Angiography Projection Imaging and 3D SPIE Medical Imaging

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  1. DICOM WG-02 Advances in X-Ray Angiography Projection Imaging and 3D SPIE Medical Imaging 2007, San Diego Authors: Tim Becker European Society of Cardiology Heinz Blendinger Siemens Medical Solutions Bas Revet Philips Medical Systems Francisco Sureda GE Healthcare (Speaker) Rainer Thieme Siemens Medical Solutions (Chair DICOM WG-02)

  2. Presentation Outline Introduction • Present and future of X-Ray Angiography in DICOM 2D Projection Images • Application Cases of the Enhanced XA SOP Class 3D Reconstruction from Projections • Highlights of the X-Ray 3D SOP Class Presentation States • Needs for enhanced presentation of 2D and 3D Conclusions

  3. Overview of X-Ray Angiography in DICOM Work in Progress Approved in the Standard X-Ray Acquisition Supp 94: Radiation Dose Reporting Follow-up of PAS by IEC MT38 – 62B 2D Projection Images Enhanced XA Technical Document Supp 83: Enhanced XA/XRF 2D XA Presentation State 3D Reconstruction Supp 116: X-Ray 3D Storage 3D XA Presentation State

  4. Workflow 2D X-Ray Angiography SOP CLASS X-Ray 2D Projection SOP Class X-Ray Acquisition Procedure SOP CLASS 2D Presentation State SOP Class Presentation Procedure Visualization Visualization 2D Visualization System X-Ray Acquisition System

  5. Enhanced XA: 2D projection images Supplement 83 • 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? • Technical Document: • 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

  6. Enhanced XA: 2D projection images • Enhanced XA Technical Document contains: • 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

  7. 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 N FRAME 1 FRAME i 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

  8. 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

  9. 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 Detector Description Patient Position Description X-Ray Table Description X-Ray Positioner Description FOV Description

  10. Enhanced XA - X-Ray Table vs. Isocenter At1 At3 At2 Ot Table Position: Table X Position to Isocenter (0018,9466) Table Y Position to Isocenter (0018,9467) Table Z Position to Isocenter (0018,9468) Table Angles: At1 = Table Horiz. Rotation (0018,9469) At2 = Table Head Tilt (0018,9470) At3 = Table Cradle Tilt (0018,9471)

  11. Enhanced XA - X-Ray Positioner vs. Isocenter Positioner Angles: Ap1 = Positioner Iso Primary (0018,9463) Ap2 = Positioner Iso Secondary (0018,9464) Ap3 = Positioner Iso Rotation (0018,9465) SID = Dist. Source-Detector (0018,1110) ISO = Dist. Source-ISO (0018,9402)

  12. Enhanced XA – Detector and FOV Aidet idet Ajdet Physical Detector Area i jdet FOV origin (FOVidet, FOVjdet) FOV Ai j Aj FOV column dimension Iso-center position (ISOidet, ISOjdet) ISO FOV row dimension Detector: Field of View: Adet = Detector Element Spacing (0018,7022) Detector Binning (0018,701A) Position of Isocenter Projection (0018,9430) FOV Origin (0018,7030) FOV Dimensions (0018,9461) FOV Rotation (0018,7032) FOV Horizontal Flip (0018,7034) Ai, Aj = Imager Pixel Spacing (0018,1164)

  13. Enhanced XA – 3D/2D Registration Table run #1 Table run #2 Positioner run #2 SID, ISO, FOV run #2 +Zp +Xp +Yp +X +X +X +Z +Z +Z O O O P1 (x,y,z) P1t (xt,yt,zt) fa(P1, Table1) P2 (x,y,z) fb(P1t, Table2) P2p (xp,yp,zp) fc(P2, Positioner2) P2(i,j) fd(P2, SID, ISO, FOV) +Y +Y +Y

  14. Enhanced XA – Standard Display Pipeline Display VOI LUT P LUT Stored Values Pixel values transformed for specific application (if TO_LINEAR, then pixel values proportional to the X-ray beam intensity) Pixel Intensity Relationship LUT Application Pixel Intensity Relationship LUT Sequence (0028,9422) 1 to N Pixel values transformed for specific application Application Pixel Intensity Relationship LUT Pixel Intensity Relationship LUT Sequence (0028,9422) 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

  15. Enhanced XA – Variable Review Settings 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 Acq. Frame rate: 15.0 Purpose: Contrast Media Acq. Frame rate: 8.0 Purpose: Contrast Media Acq. Frame rate: 4.0 Purpose: X-Ray control Item 1 >Start Trim (0008,2142) = 14 = 1 = 6 >Stop Trim (0008,2143) = 13 = 5 = 19 = DISPLAY = SKIP = DISPLAY >Skip Frame Range Flag (0008,9460) = 8.0 = n/a = 15.0 >Recom. Display Frame Rate (0008,9459) Item 2 >Start Trim (0008,2142) >Stop Trim (0008,2143) >Skip Frame Range Flag (0008,9460) > Recom. Display Frame Rate (0008,9459) Item 3 >Start Trim (0008,2142) >Stop Trim (0008,2143) >Skip Frame Range Flag (0008,9460) > Recom. Display Frame Rate (0008,9459) FRAME ACQUISITION: Frame Display Sequence (0018,7022) DICOM ENCODING: XA/XRF Multi-frame Presentation Module

  16. Enhanced XA – Pixel Shift per frame (1/2) Item 1 >Mask Operation (0028,6101) = AVG_SUB = AVG_SUB >Subtraction Item ID (0028,9416) = 101 = 100 Sub Left Sub Right >Applicable Frame Range (0028,6102) = 2\3 = 2\3 = 1 = 1 >Mask Frame Numbers (0028,6110) = Right leg = Left leg >Mask Operation Explanation (0028,6190) mask mask Item 2 >Mask Operation (0028,6101) >Subtraction Item ID (0028,9416) >Applicable Frame Range (0028,6102) Pixel Shift 0.0 \ 0.0 Pixel Shift 0.0 \ 8.0 >Mask Frame Numbers (0028,6110) >Mask Operation Explanation (0028,6190) Pixel Shift 1.0 \ 2.0 Pixel Shift 1.0 \ 9.0 FRAME ACQUISITION and PROCESSING: Frames DICOM ENCODING: Mask Module #1 Mask Subtraction Sequence (0028,6100) #2 #3

  17. Enhanced XA – Pixel Shift per frame (2/2) Sub Left Sub Right mask mask Item 1 = 100 = 100 = 101 = 101 >>Subtraction Item ID (0028,9416) = 0.0\8.0 = 1.0\9.0 = 0.0\0.0 = 1.0\2.0 >>Mask Sub-pixel Shift (0028,6114) Pixel Shift 0.0 \ 0.0 Pixel Shift 0.0 \ 8.0 Item 2 >>Subtraction Item ID (0028,9416) >>Mask Sub-pixel Shift (0028,6114) Pixel Shift 1.0 \ 2.0 Pixel Shift 1.0 \ 9.0 Item 1 >>Subtraction Item ID (0028,9416) >>Mask Sub-pixel Shift (0028,6114) Item 2 >>Subtraction Item ID (0028,9416) >>Mask Sub-pixel Shift (0028,6114) DICOM ENCODING: Frame Pixel Shift Per-Frame FRAME ACQUISITION and PROCESSING: Per-frame Functional Group Seq (0028,6100) Frames Item 2 Frame #2 >Frame Pixel Shift Seq (0028,9415) #1 #2 Item 3 Frame #3 #3 >Frame Pixel Shift Seq (0028,9415)

  18. Enhanced XA - Projection Pixel Size Calibration D D = # Px * Px * SOD / SID #Px SOD = ISO - (TH - TO) / cos°(Beam Angle) Isocenter Beam Angle SID ISO D TH TO Table X - R ay Source 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)

  19. Workflow 3D X-Ray Angiography SOP CLASS SOP CLASS X-Ray 2D Projection SOP Class 3D Storage SOP Class X-Ray Acquisition Procedure Reconstruction Procedure SOP CLASS 3D Presentation State SOP Class Presentation Procedure X-Ray Calibration Procedure Calibration Data Proprietary Visualization Visualization X-Ray Acquisition System 3D Reconstruction System 3D Visualization System

  20. X-Ray 3D Angiography Supplement 116 • 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 • ...

  21. X-Ray 3D Angiography - Modules & Functional Groups • Series • General Series • Clinical Trial Series • Enhanced Series • Frame of Reference • Frame of Reference • Equipment • General Equipment • Enhanced General Equipment • Functional Groups • Pixel Measures • Frame Content • Plane Position • Plane Orientation • Referenced Image • Derivation Image • Cardiac Trigger • Frame Anatomy • Pixel Value Transformation • Frame VOI LUT • Real World Value Mapping • Contrast/Bolus Usage • Respiratory Trigger • Image • Image Pixel • Enhanced Contrast/Bolus • Device • Intervention • Acquisition Context • Multi-frame Functional Groups • Multi-frame Dimension • Cardiac Synchronization • Respiratory Synchronization • Patient Orientation • SOP Common NEW • X-Ray 3D Frame Type NEW • Image-Equipment Coordinate Relationship NEW • X-Ray 3D Image • X-Ray 3D Angiographic Image Contributing Sources • X-Ray 3D Angiographic Acquisition • X-Ray 3D Reconstruction

  22. X-Ray 3D Angiography – Reference to 2D Mask Contrast Source #1: Contrib. SOP Inst = SOP Inst “A” M1... ...M2 C1... ...C2 Acq #1: Source Img Seq = A: M1 to M2 Reconstruction 1 Reconstruction 2 Acq #2: Source Img Seq = A: C1 to C2 Mask = 1 Recon #1: Acquisition Index SUB = 1\2 Recon #2: Acquisition Index 1... ...N N+1... ...N+k = 1 Frames #1 to #N: Recon Index = 2 Frames #N+1 to #N+k: Recon Index 2D Projection SOP Instance «A» Contributing SourcesSequence (0018,9506) SOP Instance description X-Ray 3D Acquisition Sequence (0018,9507) Acquisition description X-Ray 3D Reconstruction Sequence (0018,9530) Reconstruction description Per-Frame Func Groups Sequence (5200,9230) Frame description X-Ray 3D SOP Instance

  23. X-Ray 3D Angiography - Relationship to Equipment +Z +X +Y Image to Equipment Matrix (0028,9520) Equipment Coordinate System of the 2D projections Patient Oriented Coordinate System of the 3D slices P (Ax, Ay, Az) P (Bx, By, Bz)

  24. Enhanced XA 2D and 3D – Presentation State General needs for Enhanced Multi-frame • Extend presentation settings to “per-frame“ (windowing...) Needs for 2D X-Ray Angiography • Specify enhanced subtraction pipeline: • More specific LUTs to apply during subtraction, % anatomical background • Enhanced pixel shift: • by regions, “elastic“ pixel shift • Other processing: edge enhancement... • Needs for 3D • Presentation features common to all 3D • Speficic presentation of X-Ray 3D Angiography: • Acquisition 3D shutter for collimation • Volume Subtraction and voxel shift

  25. X-Ray 3D Angiography – Presentation State Example: 3D Mask Subtraction • 3D Mask Subtraction Sequence • Mask Operation: DT: Volume Selection • Applicable Volume: Pair of Frame Numbers • Mask Volume: Pair of Frame Numbers • Mask Voxel Shift: Triple of Float Numbers • Mask Operation Explanation: Free Text • Mask Selection Mode: DT: SYSTEM or USER • Recommended Viewing Mode: DT: SUB or NAT

  26. X-Ray 3D Angiography – Presentation State Example: Volume Regions (shutter) • Volume Region Sequence • Region Purpose : DT: DISPLAY SHUTTER or ROI • Region Display Mode : DT: DISPLAY or HIDE • Region Definition Method : Enumerated Values • ... Punch Hole: EV: ELLIPSE or POLYGON Plane: Orientation, Position, inside or outside Frame: EV: ELLIPSE or POLYGON or BITMAP

  27. Conclusions Enhanced XA Technical Document • Published in new supplement, to be included in the DICOM Part 17 by end of 2007 • Will facilitate the adoption of the Enhanced XA X-Ray 3D Angiography SOP Class • Approved in Standard • Same volumetric representation as Enhanced CT/MR Presentation States • New Work Item proposal to define enhanced Presentation States for 2D and 3D datasets Contact WG-02 chairman: Rainer.Thieme@siemens.com

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