DICOM WG02 Advances in XRay Angiography Projection Imaging

DICOM WG-02 Advances in X-Ray Angiography Projection Imaging and 3 D SPIE Medical Imaging 2009, Orlando Authors: Tim Becker Heinz Blendinger Bas Revet Francisco Sureda Rainer Thieme European Society of Cardiology Siemens Healthcare Philips Healthcare GE Healthcare (Speaker) Siemens Medical Solutions (Chair DICOM WG-02) 1

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

Overview of X-Ray Angiography in DICOM Approved in the Standard X-Ray Acquisition Supp 94: Radiation Dose Reporting 2 D Projection Images Follow-up of PAS by IEC MT 38 – 62 B Follow-up of IHE REM Profile Supp 139 -PC: Supp 83: Enhanced XA/XRF 3 D Reconstruction Work in Progress Supp 116: X-Ray 3 D Storage Enhanced XA Informative Annex Supp 140 -PC: Presentation State Multi-Dimensional Presentation State 3

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

Enhanced XA: 2 D 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 5

Enhanced XA: Supplement 139 X-Ray 2 D Projection X-Ray Acquisition Modality Enhanced XA SOP CLASS Applications – General Definitions: • Time relationships, Acquisition Geometry, Pixel Size calibration – Application Use Cases • Acquisition: Waveform synch, Mechanical Movement, X-Ray controls… • Image Registration: 3 D structures projected on 2 D images • Display: Standard pipeline, multi-mask subtraction, per-frame pixel shift • Review: Variable review settings per group of frames • Processing: Projection pixel calibration 6

Enhanced XA – Time Relationships Content Date (0008, 0023) Content Time (0008, 0033) Frame “i” Acquisition Datetime Frame “ 1” Acquisition Datetime (0018, 9074) Acquisition Datetime (0008, 002 A) Frame “ 1” Reference Datetime (0018, 9151) Frame “N” Reference Datetime Frame “i” Reference Datetime … … FRAME 1 Frame “N” Acquisition Datetime FRAME i Frame “ 1” Acquisition Duration (0018, 9220) time FRAME N Frame “N” 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 7

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” Q S T NOTE: Positioner angle values, table position values etc… are measured at the Frame Reference Datetime 8

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 – X-Ray Tube Current in m. A (0018, 9330) of frame « i » = k. Vpi = m. Ai 9

Enhanced XA – Acquisition Geometry System set up PATIENT position on the Table Image Transformation X-Ray Acquisition TABLE movement Patient Position Description POSITIONER movement X-Ray Table Description Pixel Data Storage Detector Binning Detector Description X-Ray Positioner Description X-Ray Isocenter Reference System Macro X-Ray Geometry Macro FOV Rotation & Horiz Flip FOV Description X-Ray Field of View Macro XA/XRF Acquisition Module X-Ray Detector Module Image Pixel Module 10

Enhanced XA – 3 D/2 D Registration Acquisition #1 Acquisition #2 +Z O +X +Y Table Movement +Z O +X +Y +Z O Positioner Movement SID, ISO, FOV change +X +Y +Zp +Z O +X +Yp +Xp +Y P 1 (x, y, z) P 1 t (xt, yt, zt) P 2 (x, y, z) P 2 p (xp, yp, zp) P 2(i, j) fa(P 1, Table 1) fb(P 1 t, Table 2) fc(P 2, Positioner 2) fd(P 2, SID, ISO, FOV) 11

Enhanced XA – Standard Display Pipeline Shape = “IDENTITY” if (0028, 0004) = MONOCHROME 2 Shape = “INVERSE” if (0028, 0004) = MONOCHROME 1 X Modality LUT Stored Values VOI LUT Pixel Intensity Relationship LUT 1 to N Pixel Intensity Relationship LUT Sequence (0028, 9422) Pixel Intensity Relationship LUT Pixel values transformed for specific application (if TO_LINEAR, then pixel values proportional to the X-ray beam intensity) Display Application “TO_LINEAR” is required if Pixel Intensity Relationship (0028, 1040) = LOG Pixel values transformed for specific application Application Pixel Intensity Relationship LUT Sequence (0028, 9422) 12

Enhanced XA – Variable Review Settings FRAME ACQUISITION: 1 2 3 4 5 Acq. Frame rate: 4. 0 Purpose: X-Ray control 6 7 8 9 10 11 12 13 Acq. Frame rate: 15. 0 Purpose: Contrast Media 14 15 16 17 18 19 Acq. Frame rate: 8. 0 Purpose: Contrast Media Frame Display Sequence (0018, 7022) DICOM ENCODING: XA/XRF Multi-frame Presentation Module Item 1 >Start Trim (0008, 2142) >Stop Trim (0008, 2143) >Skip Frame Range Flag (0008, 9460) >Recom. Display Frame Rate (0008, 9459) = = 1 5 SKIP 4. 0 Item 2 >Start Trim (0008, 2142) >Stop Trim (0008, 2143) >Skip Frame Range Flag (0008, 9460) > Recom. Display Frame Rate (0008, 9459) = = 6 13 DISPLAY 15. 0 Item 3 >Start Trim (0008, 2142) >Stop Trim (0008, 2143) >Skip Frame Range Flag (0008, 9460) > Recom. Display Frame Rate (0008, 9459) = = 14 19 DISPLAY 8. 0 13

Enhanced XA – Pixel Shift per frame FRAME ACQUISITION and PROCESSING: Frames #1 #2 #3 Right Leg Left Leg Sub ID 101 Sub ID 100 DICOM ENCODING: Mask Module Mask Subtraction Sequence (0028, 6100) Item 1 >Mask Operation (0028, 6101) >Subtraction Item ID (0028, 9416) >Applicable Frame Range (0028, 6102) >Mask Frame Numbers (0028, 6110) >Mask Operation Expl. (0028, 6190) = AVG_SUB = 100 = 23 = 1 = Left leg Item 2 >Mask Operation (0028, 6101) >Subtraction Item ID (0028, 9416) >Applicable Frame Range (0028, 6102) >Mask Frame Numbers (0028, 6110) >Mask Operation Expl. (0028, 6190) = AVG_SUB = 101 = 23 = 1 = Right leg 14

Enhanced XA – Pixel Shift per frame FRAME ACQUISITION and PROCESSING: Frames DICOM ENCODING: Frame Pixel Shift per frame Item 2 >Frame Pixel Shift Seq (0028, 9415) Frame #2 #1 #2 Item 3 >Frame Pixel Shift Seq (0028, 9415) Frame #3 #3 15

Enhanced XA – Pixel Shift per frame FRAME ACQUISITION and PROCESSING: Frames Left Leg #1 mask #2 Pixel Shift 0. 0 8. 0 DICOM ENCODING: Frame Pixel Shift per frame Item 2 >Frame Pixel Shift Seq (0028, 9415) Item 1 >>Subtraction Item ID (0028, 9416) >>Mask Sub-pix Shift (0028, 6114) Item 3 >Frame Pixel Shift Seq (0028, 9415) #3 Pixel Shift 2. 0 10. 0 Item 1 >>Subtraction Item ID (0028, 9416) >>Mask Sub-pix Shift (0028, 6114) Frame #2 = 100 = 0. 08. 0 Frame #3 = 100 = 2. 010. 0 16

Enhanced XA – Pixel Shift per frame FRAME ACQUISITION and PROCESSING: Frames #1 #2 Right Leg Left Leg mask Pixel Shift 0. 0 8. 0 DICOM ENCODING: Frame Pixel Shift per frame Item 2 >Frame Pixel Shift Seq (0028, 9415) Item 1 >>Subtraction Item ID (0028, 9416) >>Mask Sub-pix Shift (0028, 6114) = 100 = 0. 08. 0 Item 2 >>Subtraction Item ID (0028, 9416) >>Mask Sub-pix Shift (0028, 6114) = 101 = 0. 0. 0 Item 3 >Frame Pixel Shift Seq (0028, 9415) #3 Pixel Shift 0. 0 -7. 0 2. 0 10. 0 Frame #2 Frame #3 Item 1 >>Subtraction Item ID (0028, 9416) >>Mask Sub-pix Shift (0028, 6114) = 100 = 2. 010. 0 Item 2 >>Subtraction Item ID (0028, 9416) >>Mask Sub-pix Shift (0028, 6114) = 101 = 0. 0-7. 0 17

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 TO = Dist. Table to Object Beam Angle (0018, 9449) SID = Dist. Source-Detector ISO = Dist. Source-ISO (0018, 9402) DPx = Imager Pixel Spacing #Px Isocenter Beam Angle SID D (0018, 1130) (0018, 9403) (0018, 1110) (0018, 1164) ISO TH TO Table D = # Px * D Px * SOD / SID SOD = ISO - (TH- TO) / cos°(Beam Angle) X-Ray Source 18

XA/XRF Projection Presentation State 19

Supplement 140: new XA GSPS IOD (for 2 D) 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 20

Supplement 140: new XA GSPS IOD (for 2 D) 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 21

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 22

XA Grayscale Softcopy Presentation State mask subtraction & regional pixel shift If Pixel Intensity Relationship is not LOG Else SUB Contrast Frame(s) Else « TO_LOG » LUT VOI LUT … Pixel Shift & Anatomic Background Visibility If Pixel Intensity Relationship is not LOG « TO_LOG » LUT Mask Frame(s) 23

XA Grayscale Softcopy Presentation State Regional pixel shift Applicable pixel shift in case of multiple pixel shift regions 24

Sup 140 – Example of Regional Pixel Shift Mask frame: non-injected structures (bones, soft-tissues…) 25

Sup 140 – Example of Regional Pixel Shift Contrast frame: injected vessels – background structures moved since the mask acquisition 26

Sup 140 – Example of Regional Pixel Shift Subtraction without pixel shift: background structures are visible 27

Sup 140 – Example of Regional Pixel Shift: Select region 1 28

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 29

Sup 140 – Example of Regional Pixel Shift Mask Pixel Shift (Column) Mask Pixel Shift (Row) 30

Sup 140 – Example of Regional Pixel Shift Mask Pixel Shift (Column) Mask Pixel Shift (Row) 31

Sup 140 – Example of Regional Pixel Shift Mask Pixel Shift (Column) Mask Pixel Shift (Row) … until background structures are not visible anymore 32

Sup 140 – Example of Regional Pixel Shift: Select region 2 33

Sup 140 – Example of Regional Pixel Shift Mask Pixel Shift (Column) Regional Pixel Shift: Apply shift to mask on region 2 34

Sup 140 – Example of Regional Pixel Shift: Select region 3 35

Sup 140 – Example of Regional Pixel Shift Mask Pixel Shift (Column) Regional Pixel Shift: Apply shift to mask on region 3 36

Sup 140 – Example of Regional Pixel Shift Subtraction with regional pixel shift: background structures are not visible anymore 37

3 D X-Ray Angiography 38

Workflow 3 D X-Ray Angiography SOP CLASS X-Ray Acquisition Procedure X-Ray 2 D Projection SOP Class Reconstruction Procedure 3 D Storage SOP Class SOP CLASS In progress 3 D Presentation State SOP Class X-Ray Calibration Procedure Presentation Procedure Calibration Data Proprietary Visualization X-Ray Acquisition System 3 D Reconstruction System Visualization 3 D Visualization System 39

X-Ray 3 D Angiography Supplement 116 – In standard 2007 – – New SOP Class for Multi-frame X-Ray 3 D 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 3 D visualization (slices) References to 2 D projections Description of the reconstruction application Relationship to the Equipment Coordinate System. . . 40

X-Ray 3 D 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 Optimized 3 D Reconstruction Frame #2: X-ray settings 2 Geometry settings 2 Frame #1: X-ray settings 1 Geometry settings 1 41

X-Ray 3 D Angiography – Reference to 2 D Contributing Sources Sequence (0018, 9506) 2 D Projection SOP Instance «A» Mask M 1. . . Contrast. . . M 2 C 1. . . Source #1: Contrib. SOP Inst = SOP Inst “A” SOP Instance description . . . C 2 X-Ray 3 D Acquisition Sequence (0018, 9507) Reconstruction 1 Reconstruction 2 Acq #1: Source Img Seq = A: M 1 to M 2 Acq #2: Source Img Seq = A: C 1 to C 2 Acquisition description X-Ray 3 D Reconstruction Sequence (0018, 9530) Mask SUB Recon #1: Acquisition Index Recon #2: Acquisition Index Reconstruction description 1. . . N N+1. . . X-Ray 3 D SOP Instance . . . N+k =1 = 12 Per-Frame Func Groups Sequence (5200, 9230) Frames #1 to #N: Recon Index =1 Frames #N+1 to #N+k: Recon Index =2 Frame description 42

X-Ray 3 D Angiography - Relationship to Equipment Image to Equipment Matrix (0028, 9520) Patient Oriented Coordinate System of the 3 D slices Equipment Coordinate System of the 2 D projections P (Bx, By, Bz) P (Ax, Ay, Az) +Z O +X +Y Enhanced XA: Isocenter Reference System 43

X-Ray 3 D Angiography Presentation State 44

X-Ray 3 D Angiography – Presentation State Needs for 3 D Angiography Presentation – Presentation features common to all 3 D – Speficic presentation of X-Ray 3 D Angiography: • Acquisition 3 D 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 • 2 D-3 D blending presentation (3 D conic projection on 2 D fluoroscopy) N-Dimensional Presentation State • Work Item 2008 -04 -C. Addresses needs of multi-modalities • Led by Working Group 11, participation of Web 3 D and other working groups • Supplement in progress. . . 45

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 3 D Angiography New IOD approved in Standard 2007 (Sup 116) 3 D Presentation State on-going. . . Contact WG-02 chairman: francisco. sureda@med. ge. com 46