Softcopy and Hardcopy Image Consistency

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Softcopy and Hardcopy Image Consistency

• Cor Loef
• Philips Medical Systems
• IHE Planning and Technical Committees

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IHE Integration Profiles
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Consistent Presentation of Images

• With films, image quality was the imaging
  department problem.
• Softcopy image distribution across the healthcare
  enterprise
• Opportunity with radiology digitalization
• Avoid lost films, reduces delays
• Increases utilization of staff and equipment
• But quality and consistency need to be adressed
• This IHE Integration Profile is the cost
  effective solution to ensure that image quality
  is maintained across different monitors and film
  producing devices.

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Consistent Presentation of Images Requires
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• Calibration of the Softcopy Display and the
  Hardcopy Output Devices using DICOM Grayscale
  Standard Display Function
• Creating Hardcopy Output Using DICOM Basic Print
  with Presentation LUT Support
• Saving the Softcopy Display Viewing Parameters
  using DICOM Grayscale Softcopy Presentation State

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3
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The Grayscale Image Presentation Problem
The appearance of grayscale images displayed on
different types of softcopy display devices or
printed on different types of hardcopy output
devices is in general inconsistent and at times
may impact clinical perception.
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The Grayscale Consistency Problem

• Optimal image viewing parameters (e.g. window/
  level) selected on one device appear different
  when displayed on a different device
• Device capabilities/ characteristics vary - the
  same number of gray levels cannot be rendered or
  perceived on different devices
• Displayed images look different from printed
  images
• other

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Problems of Inconsistency

• VOI chosen on one display device
• Rendered on another with different display
• Mass expected to be seen is no longer seen

mass visible
mass invisible
Slide Provided by David Clunie
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Problems of Inconsistency
0.5
1.0

• Not all display levelsare perceivable on
  alldevices

1.5
3.0
Slide Provided by David Clunie
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Problems of Inconsistency
0.5
1.0

• Not all display levelsare perceivable on
  alldevices

1.5
3.0
Slide Provided by David Clunie
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Problems of Inconsistency

• Printed images dont looklike displayed images

Slide Provided by David Clunie
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Causes of Inconsistency

• Display devicesvary in the maximumluminance
  they canproduce
• Display CRT vs. film on a light box is an extreme
  example

1.0
.66
Slide Provided by David Clunie
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To Achieve Grayscale Consistency, Hardcopy Output
and Softcopy Viewing Devices Have to Be Properly
Calibrated
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• The DICOM Standard Defines
• A standard curve, the Grayscale Standard
  Display Function (GSDF), against which different
  types of display and hardcopy output devices
  should be calibrated

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Printer Calibration Tools (Densitometer)
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Display Calibration Tools (Photometer)
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DICOM GSDF
Slide Provided by David Clunie
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Perceptual Linearization
Slide Provided by David Clunie
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Monitor Characteristic Curve
Monitor Characteristic Curve
100
10
0.1
Ambient Light
0.01
0
50
100
150
200
250
300
Digital Driving Level
Slide Provided by David Clunie
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Standard Display Function
Slide Provided by David Clunie
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Standardizing a Display
Slide Provided by David Clunie
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Standardizing a Display
Slide Provided by David Clunie
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To Achieve Consistent Presentation of Images, the
DICOM Standard Defines
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• Basic Print Management with Presentation Look Up
  Table, for controlling the consistent appearance
  of preformatted images on printed output

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DICOM Grayscale Image Transformation Model
e
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Basic Print Management Meta SOP Class
Slide Provided by Don Van Syckle
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Basic Print Request with Presentation LUT
Print
Print
Composer
Server
Print Composer
Print Request
DICOM Film Session N-CREATE
DICOM Presentation LUT N-CREATE
DICOM Film Box N-CREATE
DICOM Image Box N-SET
DICOM Film Box N-ACTION
DICOM Film Session N-ACTION
Print Server
Print Status (DICOM N-EVENT-REPORT)
Printer Status
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Basic Print Request with Presentation LUT

• IHE Transaction - a Print Composer Actor issues a
  DICOM Print request to a Print Server Actor. The
  Print request includes a Presentation LUT for
  display consistency.

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Basic Print Request with Presentation LUT

• Print Composer A system that generates DICOM
  print requests as a DICOM Print SCU. Print
  composer has to apply Presentation State image
  manipulations, and requests to Print server will
  specify P-Values in the form of Presentation
  Look-Up Tables (Presentation LUTs).
• Print Server A system that accepts and
  processes DICOM print requests as a DICOM Print
  SCP and performs image rendering on hardcopy
  media. The system must support pixel rendering
  to optical density according to the DICOM
  Grayscale Standard Display Function.

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Basic Print Request with Presentation LUT

• Required transaction for both Print Composer and
  Print Server Actors
• Print Composer shall be grouped with one of the
  following
• Acquisition Modality Actor
• Image Manager Actor
• Image Display Actor
• Image Creator Actor

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To Achieve Consistent Presentation of Images, the
DICOM Standard Defines
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• Grayscale Softcopy Presentation State (GSPS), an
  object for storing and communicating the
  parameters that describe how an image or set of
  images should be displayed. A GSPS object
  contains references to the images it applies to,
  and the transformations (grayscale
  transformations, shutter transformation, image
  annotation, spatial transformations, and
  displayed area annotation) that should be applied
  when the images are presented on a softcopy
  display, or printed on film.

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Consistent Presentation of Images
Referring Physician or Reviewing Radiologist
Reporting Radiologist
Presentation State
Presentation LUT
Grayscale Standard
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GSPS Module Table
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Grayscale Softcopy Presentation State

• Composite object containing the image display
  settings parameters
• Composite object links to one or more images
  (Series, filters) stored using same Study
  Instance UID (same Storage SOP Class!)
• Uses regular Storage services (C-STORE) uses
  Query/Retrieve services
• GSPS SOP Instances are immutable changes require
  a new SOP Instance UID
• Note generation and specific application of GSPS
  is outside the scope of DICOM, but not outside
  the scope of IHE (e.g. Presentation of Grouped
  Procedures)

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GSPS Stored, and Query/Retrieve GSPS

• IHE Transaction - an Acquisition Modality or
  Image Creator Actor sends a DICOM GSPS C-STORE
  request to an Image Archive Actor
• IHE Transaction - an Image Display Actor issues a
  C-FIND request to an Image Manager Actor
• IHE Transaction - an Image Display Actor issues a
  C-MOVE request to an Image Archive Actor

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Creator Presentation State Stored
Image Creator
Image Archive
C-STORE (Presentation State Stored)
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Query for Grayscale Softcopy Presentation States
Image Archive
Image Display
Query/Retrieve Presentation States
(C-FIND/C-MOVE)
Presentation States (C-STORE)
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IHE Year 3 Presentation State Specific Query
Matching and Return Keys
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Consistent Presentation of Images
Display
Print
Acquire
Slide Provided by David Clunie
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Questions?

• Documents Available On the Web at

www.rsna.org/IHE or www.himss.org