DICOM INTERNATIONAL DICOM INTERNATIONAL CONFERENCE & SEMINAR April 8-10, 2008 Chengdu, China April 9, Application cases using the Enhanced XA SOP Class Tim Becker Heinz Blendinger Bas Revet Francisco Sureda Rainer Thieme European Society of Cardiology Siemens Healthcare Philips Medical Systems GE Healthcare Siemens Healthcare (Chair DICOM WG-02) Working Group 02 – Projection Radiography and Angiography

April 9, Enhanced XA SOP Class Defined in Supplement 83, in Standard 2006 –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 Inter-operability is improved in multiple domains –New supplement in progress for DICOM Part 17 (informative): Describes use cases where the Enhanced XA provides better solutions Provides encoding guidelines for implementers, both creators and users of the Enhanced XA SOP Class

April 9, Examples of application domains that are improved by using the Enhanced XA SOP Class –Review –Review: Variable review settings per groups of frames –Display –Display: Standard pipeline, per-frame pixel shift –Processing, Measurements –Processing, Measurements: Projection pixel calibration –Quality Control –Quality Control: X-Ray parameters per-frame –Acquisition –Acquisition: Mechanical Movement –Image Registration –Image Registration: 3D structures projected on 2D image Application Domains X-Ray Acquisition Modality X-Ray 2D Projection Enhanced XA SOP CLASS Applications

April 9, Cine Review Application case #1 acquisition settingsvary during the image acquisition –The acquisition settings vary during the image acquisition. –The frames are grouped by common settings –Viewing applications need to know how to review the groups of frames based on their settings (e.g. frame rate, duration, subtraction, anatomical background degree…). Solution with Enhanced XA review settings of each group of frames –Allows to describe the review settings of each group of frames of the multi-frame image, in terms of: whether or not the group shall be displayed. frame rate and duration, subtracted or not, and anatomical background degree, edge enhancement filter percentage.

April 9, Cine Review DICOM ENCODING: XA/XRF Multi-frame Presentation Module Frame Display Sequence (0018,7022) 1234 Acq. Frame rate: 4.0 Purpose: X-Ray control 5 Item 1 >Start Trim (0008,2142) >Stop Trim (0008,2143) >Skip Frame Range Flag (0008,9460) >Recom. Disp Frame Rate (0008,9459) = 1 = 5 = SKIP = Acq. Frame rate: 15.0 Purpose: Contrast Media Item 2 >Start Trim (0008,2142) >Stop Trim (0008,2143) >Skip Frame Range Flag (0008,9460) >Recom. Disp Frame Rate (0008,9459) = 6 = 13 = DISPLAY = Acq. Frame rate: 8.0 Purpose: Contrast Media 1819 Item 3 >Start Trim (0008,2142) >Stop Trim (0008,2143) >Skip Frame Range Flag (0008,9460) >Recom. Disp Frame Rate (0008,9459) = 14 = 19 = DISPLAY = 8.0 FRAME ACQUISITION

April 9, Image Display and Processing Application case #2 display the pixel data consistently –Viewing applications need to display the pixel data consistently as in the acquisition system, by applying basic processing. know the relationship between the pixel data and the X-Ray –Post-processing applications need to know the relationship between the pixel data and the X-Ray, to optimize advanced image processing and quantitative measurements of density. Solution with Enhanced XA standard display pipeline relationship between pixel value and X-Ray intensity –Allows to describe the standard display pipeline separately from the description of the relationship between pixel value and X-Ray intensity.

April 9, Image Display and Processing Stored Values VOI LUTP LUT Display Pixel Intensity Relationship LUT Pixel values transformed for specific application (if TO_LINEAR, then pixel values proportional to the X-ray beam intensity) Pixel Intensity Relationship LUT Sequence (0028,9422) Application Pixel Intensity Relationship LUT Pixel values transformed for specific application Pixel Intensity Relationship LUT Sequence (0028,9422) 1 to N Application “TO_LINEAR” is required if Pixel Intensity Relationship (0028,1040) = LOG Shape = “IDENTITY” if (0028,0004) = MONOCHROME2 Shape = “INVERSE” if (0028,0004) = MONOCHROME1 X Modality LUT

April 9, Complex Pixel Shift Application case #3 mask and contrast frames organs have moved independently to each other –The image acquisition contains mask and contrast frames to be subtracted during the display. Two or more background organs have moved independently to each other between the mask and contrast acquisition. different pixel shift –The acquisition system has determined different pixel shift values to be applied to each organ. –Viewing applications need to know the various pixel shift values to be applied sequentially to the subtracted image. Solution with Enhanced XA several subtraction items –Allows to describe several subtraction items, each one having an associated pixel shift value

April 9, Complex Pixel Shift Mask Subtraction Sequence (0028,6100) #1 #2 #3 Frames 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 = 2\3 = 1 = Right leg Right Leg Sub ID 101 DICOM ENCODING: Mask Module FRAME ACQUISITION and PROCESSING: 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 = 2\3 = 1 = Left leg Left Leg Sub ID 100

April 9, Complex Pixel Shift Item 2 >Frame Pixel Shift Seq (0028,9415) Item 3 >Frame Pixel Shift Seq (0028,9415) Frame #2 Frame #3 #1 #2 #3 Frames DICOM ENCODING: Frame Pixel Shift Per-Frame FRAME ACQUISITION and PROCESSING: Item 1 >>Subtraction Item ID (0028,9416) >>Mask Sub-pix Shift (0028,6114) = 100 = 0.0\0.0 Item 1 >>Subtraction Item ID (0028,9416) >>Mask Sub-pix Shift (0028,6114) = 100 = 1.0\2.0 Left Leg mask Pixel Shift 0.0 \ 0.0 Pixel Shift 1.0 \ 2.0 Item 2 >>Subtraction Item ID (0028,9416) >>Mask Sub-pix Shift (0028,6114) = 101 = 0.0\8.0 Item 2 >>Subtraction Item ID (0028,9416) >>Mask Sub-pix Shift (0028,6114) = 101 = 1.0\9.0 Right Leg mask Pixel Shift 0.0 \ 8.0 Pixel Shift 1.0 \ 9.0

April 9, Projection Pixel Size Calibration Application case #4 size of the objects –Post-processing applications need to know the pixel size in the patient, in order to measure the size of the objects projected on the image. avoid theusage of external calibration objects –To optimize the workflow, it shall avoid the usage of external calibration objects such as catheter or ruler. Solution with Enhanced XA conic projection geometry –Allows to describe the conic projection geometry of the image acquisition, including: the position of the table in the trajectory of the X-Ray beam, the distance from the object in the patient to the table top plane.

April 9, Projection Pixel Size Calibration D = # Px *  Px * SOD / SID SOD = ISO- (TH-TO) / cos°(Beam Angle) #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)  Px = Imager Pixel Spacing(0018,1164) How to convert from “pixels on image” to “mm in patient”:

April 9, Quality Control Application case #5 parameters varying during the acquisition –The image acquisition is performed with several settings and parameters varying during the acquisition. exact values of the X-Ray parameters for each frame –The quality control applications need to determine the exact values of the X-Ray parameters for each frame, and to relate them to the X-Ray beam incidence on the frames. Solution with Enhanced XA X-Ray acquisition parameters in a per- frame –Allows to describe the X-Ray acquisition parameters in a per- frame basis.

April 9, Quality Control 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 » =  t i In the Frame Acquisition Sequence (0018,9417): –KVP (0018,0060) of frame « i » = kVp i –X-Ray Tube Current in mA (0018,9330) of frame « i » = mA i

April 9, Mechanical Movement Application case #6 dynamic acquisition –One dynamic acquisition is performed with movement of the X-Ray positioner or the X-Ray table. several static acquisitions –Or several static acquisitions are performed of the same organ or object of interest 3D reconstruction –Applications need to relate the projected objects to the 3D space for 3D reconstruction and/or 3D localization. Solution with Enhanced XA Positioner and Table on an absolute reference (Isocenter) –Allows to describe the Positioner and Table on an absolute reference (Isocenter) in addition to the patient reference. Detector Area and the Field of View transformations –Allows to describe the Detector Area and the Field of View transformations to relate each pixel to the fixed reference.

April 9, Rotational Movement Frame #5: X-ray settings 5 Geometry settings 5 Optimized 3D Reconstruction Frame #2: X-ray settings 2 Geometry settings 2 Frame #3: X-ray settings 3 Geometry settings 3 Frame #4: X-ray settings 4 Geometry settings 4 Frame #1: X-ray settings 1 Geometry settings 1

April 9, Image Registration P 1 (x,y,z) Table run #1 +Y +Z +X O P 1t (x t,y t,z t ) f a (P 1, Table 1 ) P 2p (x p,y p,z p ) f c (P 2, Positioner 2 ) +Y +Z +X O Positioner run #2 +Y +Z +X O P 2 (x,y,z) f b (P 1t, Table 2 ) Table run #2 SID, ISO, FOV run #2 +Xp +Zp +Yp P 2 (i,j) f d (P 2, SID, ISO, FOV)

April 9, Conclusion The Enhanced XA SOP Class improves interoperability –It overcomes the known limitations of the current XA SOP Class and enables future applications It is open for today’s and new applications and equipments –In DICOM Standard since 2006 DICOM WG-02 currently prepares a new supplement for the Part 17 (Informative) –with practical scenarios on Enhanced XA usage