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Soft Copy Presentation State

Soft Copy Presentation State. Herman Oosterwijk, OTech Inc. PACS and DICOM training and consulting herman@otechimg.com. Scenario: Radiologist:. Radiologist:. Suspected area. Suspect. Radiologist:. Physician:. Suspect. Suspected area.

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Soft Copy Presentation State

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  1. Soft Copy Presentation State Herman Oosterwijk, OTech Inc. PACS and DICOM training and consulting herman@otechimg.com

  2. Scenario: Radiologist:

  3. Radiologist: Suspected area Suspect

  4. Radiologist: Physician: Suspect Suspected area

  5. Grayscale Softcopy Presentation State Storage: 1. Accommodate conversion of Pixels to Presentation values (P-values) Note: P-values are device independent values (defined by Grayscale Standard Display Function). 2. Preserve additional transformations, annotations, shutter, spatial xforms

  6. Softcopy Presentation State: - Separation of Stored Image Instances from Display characteristics and changes Presn param: WW, Ctr, rescl, intc. Pres State Composite Image Object n : m Presn param: WW, Ctr, rescl, intc. Presn param: WW, Ctr, rescl, intc. Image Object

  7. Softcopy Presentation State: - Separation of Images and Pres states (ctd) Examples: • Zoom applied to multiple CT slices (e.g. Spine) • Double Window Width/Ctr for CT chest • Separate Overlays that generated by CAD Reduction of data transfer and storage because only one instance needed of image data

  8. Softcopy Presentation State: • Important: Softcopy Presentation State contains parameters that are present in the image as well (e.g. WW/level): • Presentation State values/operations overrides the values in the image • If no values in Presentation State for particular operation than identity transformation • Photometric Interpretation (0028,0004) shall be ignored in Image

  9. Modality LUT Mask VOI LUT Presentation LUT Overlays, Curves Modality LUT Mask VOI LUT Presentation LUT Overlays, Curves Shutters Img Annotation Spatial Xform Displ Area Annotn Softcopy Presentation State: Image Pres State Ptr.

  10. Softcopy Presentation State: • Composite object containing the presentation state parameters • Link this Composite object to one or more images (Series, filters); stored using same Study Instance UID (same Storage SOP Class!) • Communicate with regular Storage service (C_Store); Retrieve with Query/Retrieve service • Pres State SOP Instances are immutable: changes require a new SOP Inst UID Note: generation and applying (selection) of pres states (SCU and SCP) outside scope of DICOM

  11. R e s c a l e S l o p e / I n t e r c e p t W i n d o w / L e v e l o r V O I L U T o r M o d a l i t y L U T M o d a l i t y O r i g i n a l M a s k V O I L U T L U T I m a g e ( S u b t r a c t i o n ) T r a n s f o r m a t i o n T r a n s f o r m a t i o n I m a g e D i s p . A r e a S h u t t e r S p a t i a l P - V a l u e D i s p l a y T r a n s f o r m a t i o n A n n o t a t i o n A n n o t a t i o n T r a n s f o r m a t i o n Softcopy Pres. State: Image pipeline Presentation LUT Presentation LUT Transformation e s

  12. R e s c a l e S l o p e / I n t e r c e p t W i n d o w / L e v e l o r V O I L U T o r M o d a l i t y L U T M o d a l i t y O r i g i n a l M a s k V O I L U T L U T I m a g e ( S u b t r a c t i o n ) T r a n s f o r m a t i o n T r a n s f o r m a t i o n Softcopy Pres. State: Image pipeline Presentation LUT Presentation LUT Transformation e

  13. Display look Softcopy Presentation State: Image Disp. Area Shutter Spatial P-Values Transformation Annotation Annotation Transformation Text, independent from spatial transformation Flip, Rotate, Zoom, Pan

  14. Softcopy Presentation State Module Table:

  15. Patient, Study, Series module as well as SOP Common makes this a composite object • Presentation Series specializes Modality (0008,0060) of Gnl. Series Module: “PR”

  16. MASK SHUTR IMG ANN PRES LUT VOI LUT IMAGE Modules vs Pipeline: SPATL XFORM DISPL ANN MOD LUT

  17. Presentation State Module: To identify the Pres. State object: • Instance (aka Image) number • Label, description, creation date/time, and creator’s name • Applies to which images: Ref series/image sequence • Misc: • Shutter presentation value (P-values) • Mask subtraction (average-time delay)

  18. MASK Shttr Img Anntn Spatl Xform PRES LUT VOI LUT Modality LUT Module: MOD LUT Manufacturer values to modality pixel values (Hounsfield, OD); LUT OR Rescale Slope/Interc. - Modality LUT: • LUT Descriptor: • Number of entries in table • First stored pixel value mapped • Number of bits for each entry in LUT data • Modality LUT Type: output units (OD, US) • LUT data Displ Anntn

  19. MASK Shttr Img Anntn Spatl Xform PRES LUT VOI LUT Modality LUT Module: MOD LUT Mod LUT: Displ Anntn Output LUT: Unsigned Number of entries in LUT; Number of bits for each entry: (8 or 16)---> range is 256 or 65536 Data range First Stored Pixel (FSP) value mapped (VR is defined by Pix.Repres.)

  20. MASK Shttr Img Anntn Spatl Xform PRES LUT VOI LUT Modality LUT Module: MOD LUT Rescale Slope Intercept: Displ Anntn • Linear: • Slope/ • Intercept • Example: • shift linear 2048 output values Input values

  21. MASK Shttr Img Anntn Spatl Xform PRES LUT VOI LUT Modality LUT Module: MOD LUT Issues/notes: • Provides Mod LUT for CT (is normally not part of CT Image IOD) • Output range depends on whether Mod Lut is used or rescale/Intercept: • Unsigned for Mod LUT • Defined by value of rescale slope/Intercept and Pixel representation; could be signed even if Pixel representation is unsigned Displ Anntn

  22. Shttr Img Anntn Spatl Xform PRES LUT VOI LUT MASK Module: MOD LUT MASK Mask operation: Subtract frames with fixed position or time interval: • AVG_SUB; Average subtraction: • Average frames identified by MASK Frame Numbers, shift by MASK Sub-Pixel Shift and subtract from frames Applicable Frame Range • TID; Time Interval differencing: • Subtract TID Offset from frame number to select the mask to be subtracted Displ Anntn

  23. Shttr Img Anntn Spatl Xform PRES LUT VOI LUT MASK Module: MOD LUT MASK Displ Anntn Issues/Notes: • For X-ray images, subtraction needs to be in log space relative to X-ray intensity; could be done by applying Mod LUT (if so needed) • Output is signed value, one bit longer than source frames

  24. Shttr Img Anntn Spatl Xform PRES LUT VOI LUT Module: MOD LUT MASK VOI LUT Map modality pixel values (Hounsfield) to application significant values: VOI LUT or WW/Center - VOI LUT: • LUT Descriptor: • Number of entries in table • First input value mapped • Number of bits for each entry in LUT data • LUT data Displ Anntn

  25. Shttr Img Anntn Spatl Xform PRES LUT VOI LUT Module: MOD LUT MASK VOI LUT Window Width/Center: (is better defined!) Displ Anntn width output values center Input values

  26. Shttr Img Anntn Spatl Xform PRES LUT VOI LUT Module: MOD LUT MASK VOI LUT WW/Ctr Issues/Notes: • Assume floating point calculation: • WW 1, Ctr 0: -0.5 <= value <= 0.5 • WW 100, Ctr 0: -50 <= value <= +50 • WW 4095, Ctr 2047: -0.5 <= value <= 4095.5 • Selected input range may exceed actual input range: image will be “flattened” • Output is scaled to display device OR to range of Pres LUT Displ Anntn

  27. Shttr Img Anntn Spatl Xform PRES LUT VOI LUT Module: MOD LUT MASK VOI LUT Issues/Notes: • Photometric Interpret. Is ignored • VOI LUT can have sections with negative slope • Image VOI LUT shall not be used • Only a single VOI LUT shall be present (multiple requires different Pres States); this is not the case for the VOI Lut’s as present in the images (can be multiple) Displ Anntn

  28. Shttr Img Anntn Spatl Xform SC Pres. LUT Module: MOD LUT MASK VOI LUT PRES LUT Pixels to P-values: (assumes Grayscale Display Function standard) • LUT Descriptor: • Number of entries in table • First input value mapped (always scaled to 0) • Number of bits for each entry in LUT data • LUT data • Pres LUT shape; reqd if no LUT Displ Anntn

  29. MASK Shttr Img Anntn Spatl Xform VOI LUT SC Pres LUT Module: PRES LUT MOD LUT LUT maps full range Displ Anntn Output LUT: Unsigned Number of entries in LUT; Number of bits for each entry: (8<=n<=16) Data range First Stored Pixel (FSP) value mapped; scaled to 0 (VR is US)

  30. Shttr Img Anntn Spatl Xform SC Pres. LUT Module: MOD LUT MASK VOI LUT PRES LUT Issues/Notes: • If no Pres LUT and VOI LUT, Mod LUT has to make sure that output is in P-values • LUT Shape might reflect Monochrome 1/2 in case not reflected in the pipeline before (IDENTITY-INVERSE) • No separate polarity inversion is defined • Pres LUT is Required (M); xform could be “Identity” Displ Anntn

  31. WW/ Ctr Ident SC Pr LUT VOI LUT RSC/ INT MOD LUT VR at different stages: MOD LUT MASK VOI LUT PRES LUT Pix data [Pix Repres] P-values US US US US MASK SS/US SS/US

  32. Img Anntn Spatl Xform Shutter XForm: MOD LUT MASK VOI LUT PRES LUT Two modules: • Display shutter module: • Shape: Rectangular, Circular, Polygonal • Coordinates (edge, ctr, radius, vertices) • optional Presentation (padding) Value • Bitmap Display Shutter Module: • Shape (bitmap) • Overlay group [60xx] (in Pres State Object!) • reqd Presentation (padding) Value Shttr Displ Anntn

  33. Spatl Xform Image Annotation: MOD LUT MASK VOI LUT PRES LUT Pre-spatial xform annotation (e.g. ROI shapes) • Use Overlay/Curve Activation Module: If Curve activated, only curve contained in images are activated (curves are replaced by Graphic Annotation Module in SC Pres State) If Overlay activated, could be in Image or SC Pres State object Shttr Img Anntn Displ Anntn

  34. Spatl Xform Image Annotation: MOD LUT MASK VOI LUT PRES LUT Graphic Layer: Groups related graphics, • identifies with text string, provides order number and display value (incl color) as well as free text description • Referenced from the Graphic annotation module Shttr Img Anntn Displ Anntn

  35. Spatl Xform Image Annotation: MOD LUT MASK VOI LUT PRES LUT Graphic Ann. Module: - Graphics, text or both • Bounding box OR Anchor points units: “Pixel” • Types are Polyline, Interpolated, Circle or Elipse • Graphic could be filled • Addressing: Pixel 1\1 is in between Point (0.0\0.0) and Point (1.0\1.0) Shttr Img Anntn Displ Anntn

  36. Spatl Xform Image Annotation: MASK MOD LUT VOI LUT PRES LUT Graphic Ann. Module: - Issues/Notes: • Text could be outside bounding box • Text could be in scrolling box or link to other window • Transparency, opacity or “exclusive or” of bounding box is implementation specific • “Anchor Point visibility” determines line or arrow from point to text; text might be repositioned as appropriate for zoom Shttr Img Anntn Displ Anntn

  37. Img Anntn Spatial Xform: MASK MOD LUT VOI LUT PRES LUT Rotate, Flip, Minify/Zoom and region selection: • Spatial Xform module: • Rotate (0, 90, 180, 270) CW • Horizontal flip • Displayed area module: • Top Left hand Corner and Bottom Right Hand Corner of data to be displayed relative to pixel data (1\1) Shttr Displ Anntn Spatl Xform

  38. Img Anntn Spatial Xform: MASK MOD LUT VOI LUT PRES LUT Displayed area module: Shttr Displ Anntn Spatl Xform (1\1) TLHC BRHC (Rows\columns)

  39. Img Anntn Spatial Xform: MASK MOD LUT VOI LUT PRES LUT Notes/Issues: • Area can be greater than result from spatial transformation (e.g. a 1200 by 1000 display displaying a 1k by 1k image) • Result shall be displayed as large as possible within display area (magnified if applicable) • Minification is achieved by a negative TLHC and/or BRHC greater than Rows or Columns • Rotate/Flip applied BEFORE zoom/minify Shttr Displ Anntn Spatl Xform

  40. Spatl Xform Displ. Area Annotation: MASK MOD LUT VOI LUT PRES LUT Display dependent graphics Graphic Ann. Module: Graphics, text or both • Bounding box OR Anchor points units: “DISPLAY” • Types are Polyline, Interpolated, Circle or Elipse • Graphic could be filled • Addressing: Pixel 1\1 is in between Point (0.0\0.0) and Point (1.0\1.0) Shttr Img Anntn Displ Anntn

  41. Softcopy Presentation State Conformance Statement requirements: SCU: • How are presentation attributes derived from Image, operator intervention, defaults • How is info included in IOD • Which Image Storage SOP classes are supported and can be referenced by the SC Presentation State

  42. Softcopy Presentation State Conformance Statement requirements (ctd): SCP: • How are attributes used to influence image display • Which Image Storage SOP classes are supported and may be referenced by the Sofcopy presentation State

  43. Softcopy Presentation State media extensions: • Directory Type added “Presentation” • Included below Series Directory record entry • Can be stored on a general purpose CD-R

  44. Status Softcopy Presentation State supplement: • Draft for trial implementation • Demonstration/implementation funded by DICOM committee at ECR, March ‘99 • Main contractor OTech, proj. Mgt. lake Grifin, implementation by OFFIS (U Oldenburgh) and Microtherapy (U Witten/herdecke) • Main sponsors are Imation, Philips, Siemens, GE and ISG; Image Smiths provides calibration • Software will be in available in public domain

  45. Goals Softcopy Presentation State demo: • Education of user community and sollicitation of feedback • Demonstration of this specific supplement • Promotion of early implementation and adoption Physician workstation Modality simulator Diagn workstation

  46. Softcopy Presentation State does NOT (yet) address: - Color (no Color Display function) - No screen layout issues are addressed, including size of images on screen - No query of display characteristics (like Print configuration) - No 3D display and/or image fusion (CT/MR/NM)

  47. Softcopy Presentation State provides: • Image Presentation consistency (vs grayscale consistency defined by Grayscale function) • Tighter definition of presentation parameters (WW/Ctr, etc) • Uncoupling of presentation and images; eliminates multiple instances of images with same pixel data • Address exchange of overlays and text (currently often solved with proprietary means)

  48. (Print) Presentation LUT: • Relates to Image Box, Film Box or Film Session • Normalized IOD: • Presentation LUT Module: • LUT descriptor • Explanation • LUT data • LUT Shape: IDENTITY or LIN OD (range is Min density to max density)

  49. DICOM Presentation LUT • GOAL: Consistent image quality. • Transformation of pixel values into P-values • For hardcopy, P-values are transformed into optical density • Image display can be tailored for specific modalities, applications and user preferences

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