Annex V Hanging Protocols (Informative)

The Hanging Protocol Composite IOD contains information about user viewing preferences, related to image display station (workstation) capabilities. The associated Service Classes support the storage (C-STORE), query (C-FIND) and retrieve (C-MOVE and C-GET) of Hanging Protocol Instances between servers and workstations. The goal is for users to be able to conveniently define their preferred methods of presentation and interaction for different types of viewing circumstances once, and then to automatically layout image sets according to the users’ preferences on workstations of similar capability.

The primary expectation is to facilitate the automatic and consistent hanging of images according to definitions provided by the users, sites or vendors of the workstations by providing the capability to:

How relevant image sets (e.g., from the current and prior studies) are obtained is not defined by the Hanging Protocol IOD or Service Classes.

Conformance with the DICOM Grayscale Standard Display Function and the DICOM Softcopy Presentation States in conjunction with the Hanging Protocol IOD allows the complete picture of what the users see, and how they interact with it, to be defined, stored and reproduced as similarly as possible, independent of workstation type. Further, it is anticipated that implementors will make it easy for users to point to a graphical representation of what they want (such as 4x1 versus 12x1 format with a horizontal alternator scroll mechanism) and select it.

V.1 Example Scenario

User A sits down at workstation X, with two 1024x1280 resolution screens (Figure V.1-1) that recently has been installed and hence has no user specific Hanging Protocols defined. The user brings up the list of studies to be read and selects the first study, a chest CT, together with the relevant prior studies. The workstation queries the Hanging Protocol Query SCP for instances of the Hanging Protocol Storage SOP Class. It finds none for this specific user, but matches a site specific Hanging Protocol Instance, which was set up when the workstation was installed at the site. It applies the site Hanging Protocol Instance, and the user reads the current study in comparison to the prior studies.

The user decides to customize the viewing style, and uses the viewing application to define what type of Hanging Protocol is preferred (layout style, interaction style) by pointing and clicking on graphical representations of the choices. The user chooses a 3-column by 4-row tiled presentation with a “vertical alternator” interaction, and a default scroll amount of one row of images. The user places the current study on the left screen, and the prior study on the right screen. The user requests the application to save this Hanging Protocol, which causes the new Hanging Protocol Instance to be stored to the Hanging Protocol Storage SCP.

When the same user comes back the next day to read chest CT studies at workstation X and a study is selected, the application queries the Hanging Protocol Query SCP to determine which Hanging Protocol Instances best match the scenario of this user on this workstation for this study. The best match returned by the SCP in response to the query is with the user ID matching his userid, the study type matched to the study type(s) of the image set selected for viewing, and the screen types matching the workstation in use.

A list of matches is produced, with the Hanging Protocol Instance that the user defined yesterday for chest CT matching the best, and the current CT study is automatically displayed on the left screen with that Hanging Protocol. Alternative next best matches are available to the user via the application interface’s pull-down menu list of all closely matching Hanging Protocol Instances.

Because this Hanging Protocol defines an additional image set, the prior year’s chest CT study for the same patient is displayed next to the current study, on the right screen.

The next week, the same user reads chest CTs at a different site in the same enterprise on a similar type workstation, workstation Y, from a different vendor. The workstation has a single 2048x2560 screen (Figure V.1-1). This workstation queries the Hanging Protocol Query SCP, and retrieves matching Hanging Protocol Instances, choosing as the best match the Hanging Protocol Instance used on workstation X before by user A. This Hanging Protocol is automatically applied to display the chest CT study. The current chest CT study is displayed on the left half of the 2048x2560 screen, and the prior chest CT study is displayed on the right half of the screen, with 3 columns and 8 rows each, maintaining the same vertical alternator layout. The sequence of communications between the workstations and the SCP is depicted in Figure V.1-2.

[pic]

Figure V.1-1. Spatial layout of screens for workstations in Example Scenario.

[pic]

Figure V.1-2. Sequence diagram for Example Scenario

V.2 hanging protocol internal process model

The overall process flow of Hanging Protocols can be seen in Figure V.2-1, and consists of three main steps: selection, processing, and layout. The selection is defined in the Hanging Protocol Definition Module . The processing and layout are defined in the Hanging Protocol Display Module . The first process step, the selection of sets of images that need to be available from DICOM image objects, is defined by the Image Sets Sequence of the Hanging Protocol Definition Module . This is a N:M mapping, with multiple image sets potentially drawing from the same image objects.

The second part of the process flow consists of the filtering, reformatting, sorting, and presentation intent operations that map the Image Sets into their final form, the Display Sets. This is defined in the Hanging Protocol Display Module . This is a 1:M relationship, as multiple Display Sets may draw their images from the same Image Set. The filtering operation allows for selecting a subset of the Image Set and is defined by the Hanging Protocol Display Module Filter Operations Sequence. Reformatting allows operations such as multiplanar reformatting to resample images from a volume (Reformatting Operation Type, Reformatting Thickness, Reformatting Interval, Reformatting Operation Initial View Direction, 3D Rendering Type). The Hanging Protocol Display Module Sorting Operations Sequence allows for ordering of the images. Default presentation intent (a subset of the Presentation State operations such as intensity window default setting) is defined by the Hanging Protocol Display Module presentation intent attributes. The Display Sets are containers holding the final sets of images after all operations have occurred. These sets contain the images ready for rendering to locations on the screen(s).

The rendering of a Display Set to the screen is determined by the layout information in the Image Boxes Sequence within a Display Sets Sequence Item in the Hanging Protocol Display Module. A Display Set is mapped to a single Image Boxes Sequence. This is generally a single Image Box (rectangular area on screen), but may be an ordered set of image boxes. The mapping to an ordered set of image boxes is a special case to allow the images to flow in an ordered sequence through multiple locations on the screen (e.g., newspaper columns). Display Environment Spatial Position specifies rectangular locations on the screen where the images from the Display Sets will be rendered. The type of interaction to be used is defined by the Image Boxes Sequence Item attributes. A vertically scrolling alternator could be specified by having Image Box Layout Type equal TILED and Image Box Scroll Direction equal VERTICAL.

An example of this processing is shown in Figure V.2-2. The figure is based on the Neurosurgery Planning Hanging Protocol Example contained in this Annex, and corresponds to the display sets for Display Set Presentation Group #1 (CT only display of current CT study).

[pic]

Figure V.2-1 Hanging Protocol Internal Process Model

[pic]

Figure V.2-2 Example Process Flow

V.3 Chest X-ray Hanging Protocol Example

Goal: A Hanging Protocol for Chest X-ray, PA & Lateral (LL, RL) views, current & prior, with the following layout:

[pic]

The Hanging Protocol Definition does not specify a specific modality, but rather a specific anatomy (Chest). The Image Sets Sequence provides more detail, in that it specifies the modalities in addition to the anatomy for each image set.

V.3.1 Hanging Protocol Definition Module

Hanging Protocol Name: “Chest X-ray”

Hanging Protocol Description: “Current and Prior Chest PA and Lateral”

Hanging Protocol Level: “SITE”

Hanging Protocol Creator: “Senior Radiologist”

Hanging Protocol Creation DateTime: “20020823133455”

Hanging Protocol Definition Sequence:

Number of Priors Referenced: 1

Image Sets Sequence:

Hanging Protocol User Identification Code Sequence: zero length

Hanging Protocol User Group Name: “ABC Hospital”

V.3.2 Hanging Protocol Environment Module

Number of Screens: 2

Nominal Screen Definition Sequence:

V.3.3 Hanging Protocol Display Module

Display Sets Sequence:

Partial Data Display Handling: “MAINTAIN_LAYOUT”

V.4 Neurosurgery Planning Hanging Protocol Example

Goal: A Hanging Protocol for MR & CT of Head, for a neurosurgery plan. 1Kx1K screen on left shows orthogonal MPR slices through the acquisition volume, and in one presentation group has a 3D interactive volume rendering in the lower right quadrant. In all display sets the 1Kx1K screen is split into 4 512x512 quadrants. The 2560x2048 screen has a 4 row by 3 column tiled display area. There are 4 temporal presentation groups: CT new , MR, combined CT new and MR, combined CT new and CT old .

Display Environment Spatial Position attribute values for image boxes are represented in terms of ratios in pixel space [(0/3072, 512/2560), (512/3072,0/2560)] rather than (0.0,0.0), (1.0,1.0) space, for ease of understanding the example.

[pic]

V.4.1 Hanging Protocol Definition Module

Hanging Protocol Name: “NeurosurgeryPlan”

Hanging Protocol Description: “Neurosurgery planning, requiring MR and CT of head”

Hanging Protocol Level: “SITE”

Hanging Protocol Creator: “Smith^Joseph”

Hanging Protocol Creation DateTime: “20020101104200”

Hanging Protocol Definition Sequence:

Number of Priors Referenced: 1

Image Sets Sequence:

Hanging Protocol User Identification Code Sequence: zero length

Hanging Protocol User Group Name: “ABC Hospital”

V.4.2 Hanging Protocol Environment Module

Number of Screens: 2

Nominal Screen Definition Sequence:

V.4.3 Hanging Protocol Display Module

Display Sets Sequence:

[Group #1 is CT only display (current CT)]

[pic]

[Group #2 is MR only display]

[pic]

[Group #3 is combined MR & CT]

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[Group #4 is combined CT new & CT old]

[pic]

Partial Data Display Handling: “MAINTAIN_LAYOUT”

[Link up (synchronize) the MR and CT tiled scroll panes in Display Sets 15 and 16, and the CT new and CT old tiled scroll panes in Display Sets 21 and 22]

Synchronized Scrolling Sequence:

V.5 Hanging Protocol Query Example

The following is an example of a general C-FIND Request for the Hanging Protocol Information Model – FIND SOP Class that is searching for all Chest related Hanging Protocols for the purpose of reading projection Chest X-ray. The user is at a workstation that has two 2Kx2.5K screens.

C-FIND Request:

Nesting Attribute Tag VR VL (hex) Value
Affected SOP Class UID (0000,0002) UI 0018 1.2.840.10008.5.1.4.38.2
Command Field (0000,0100) US 0002 0020H [C-FIND-RQ]
Message ID (0000,0110) US 0002 0010H
Priority (0000,0700) US 0002 0000H [MEDIUM]
Data Set Type (0000,0800) US 0002 0102H
SOP Class UID (0008,0016) UI 0000
SOP Instance UID (0008,0018) UI 0000
Hanging Protocol Name (0072,0002) SH 0000
Hanging Protocol Description (0072,0004) LO 0000
Hanging Protocol Level (0072,0006) CS 0000
Hanging Protocol Creator (0072,0008) LO 0000
Hanging Protocol Creation DateTime (0072,000A) DT 0000
Hanging Protocol Definition Sequence (0072,000C) SQ ffffffff
%item
> Modality (0008,0060) CS 0000
> Anatomic Region Sequence (0008,2218) SQ ffffffff
%item
>> Code Value (0008,0100) SH 0008 T-D3000
>> Coding Scheme Designator (0008,0102) SH 0004 SRT
>> Code Meaning (0008,0104) LO 0006 Chest
%enditem
%endseq
> Procedure Code Sequence (0008,1032) SQ 0000
> Laterality (0020,0060) CS 0000
> Reason for Requested Procedure Code Sequence (0040,100A) SQ 0000
%enditem
%endseq
Hanging Protocol User Identification Code Sequence (0072,000E) SQ 0000
Number of Priors Referenced (0072,0014) US 0000
Number of Screens (0072,0100) US 0000
Nominal Screen Definition Sequence (0072,0102) SQ 0000

The following is an example of a set of C-FIND Responses for the Hanging Protocol Information Model – FIND SOP Class, answering the C-FIND Request listed above. There are a few matches for this general query. The application needs to select the best choice among the matches, which is the second response. The first response is for Chest CT, and the third response does not match the user’s workstation environment as well as does the second.

C-FIND Response #1:

Nesting Attribute Tag VR VL (hex) Value
Affected SOP Class UID (0000,0002) UI 0018 1.2.840.10008.5.1.4.38.2
Command Field (0000,0100) US 0002 8020H [C-FIND-RSP]
Message ID Being Responded To (0000,0120) US 0002 0010H
Data Set Type (0000,0800) US 0002 0102H
Status (0000,0900) US 0002 FF00H [Pending]
SOP Class UID (0008,0016) UI 0018 1.2.840.10008.5.1.4.38.1
SOP Instance UID (0008,0018) UI 0024 1.2.840.10008.5.1.4.1.1.76392.999.2
Hanging Protocol Name (0072,0002) SH 000a CT 1 prior
Hanging Protocol Description (0072,0004) LO 0038 Dual screen layout for current and single prior chest CT
Hanging Protocol Level (0072,0006) CS 000c SINGLE_USER
Hanging Protocol Creator (0072,0008) LO 0008 Dr. Chan
Hanging Protocol Creation DateTime (0072,000A) DT 000c 200408210718
Hanging Protocol Definition Sequence (0072,000C) SQ ffffffff
%item
> Modality (0008,0060) CS 0002 CT
> Anatomic Region Sequence (0008,2218) SQ ffffffff
%item
>> Code Value (0008,0100) SH 0008 T-D3000
>> Coding Scheme Designator (0008,0102) SH 0004 SRT
>> Code Meaning (0008,0104) LO 0006 Chest
%enditem
%endseq
> Procedure Code Sequence (0008,1032) SQ 0000
> Laterality (0020,0060) CS 0000
> Reason for Requested Procedure Code Sequence (0040,100A) SQ 0000
%enditem
%endseq
Hanging Protocol User Identification Code Sequence (0072,000E) SQ 0000
%item
> Code Value (0008,0100) SH 000a 58489749P
> Coding Scheme Designator (0008,0102) SH 0008 HOSP_ID
> Code Meaning (0008,0104) LO 000e Susan H. Chan
%enditem
%endseq
Number of Priors Referenced (0072,0014) US 0002 1
Number of Screens (0072,0100) US 0002 2
Nominal Screen Definition Sequence (0072,0102) SQ 0000

C-FIND Response #2:

Nesting Attribute Tag VR VL (hex) Value
Affected SOP Class UID (0000,0002) UI 0018 1.2.840.10008.5.1.4.38.2
Command Field (0000,0100) US 0002 8020H [C-FIND-RSP]
Message ID Being Responded To (0000,0120) US 0002 0010H
Data Set Type (0000,0800) US 0002 0102H
Status (0000,0900) US 0002 FF00H [Pending]
SOP Class UID (0008,0016) UI 0018 1.2.840.10008.5.1.4.38.1
SOP Instance UID (0008,0018) UI 0020 1.2.840.123456.20030822.223344.1
Hanging Protocol Name (0072,0002) SH 000c Chest X-ray
Hanging Protocol Description (0072,0004) LO 0026 Current and Prior Chest PA and Lateral
Hanging Protocol Level (0072,0006) CS 0004 SITE
Hanging Protocol Creator (0072,0008) LO 0012 Senior Radiologist
Hanging Protocol Creation DateTime (0072,000A) DT 000e 20020823133455
Hanging Protocol Definition Sequence (0072,000C) SQ ffffffff
%item
> Modality (0008,0060) CS 0000
> Anatomic Region Sequence (0008,2218) SQ ffffffff
%item
>> Code Value (0008,0100) SH 0008 T-D3000
>> Coding Scheme Designator (0008,0102) SH 0004 SRT
>> Code Meaning (0008,0104) LO 0006 Chest
%enditem
%endseq
> Procedure Code Sequence (0008,1032) SQ 0000
> Laterality (0020,0060) CS 0000
> Reason for Requested Procedure Code Sequence (0040,100A) SQ 0000
%enditem
%endseq
Hanging Protocol User Identification Code Sequence (0072,000E) SQ 0000
Number of Priors Referenced (0072,0014) US 0002 1
Number of Screens (0072,0100) US 0002 0002H
Nominal Screen Definition Sequence (0072,0102) SQ ffffffff
%item
> Number of Vertical Pixels (0072,0104) US 0002 2560
> Number of Horizontal Pixels (0072,0106) US 0002 2048
> Display Environment Spatial Position (0072,0108) FD 0020 0.0\1.0\0.5\0.0
> Screen Minimum Grayscale Bit Depth (0072,010A) US 0002 0008H
> Application Maximum Repaint Time (0072,010E) US 0002 0064H
%enditem
%item
> Number of Vertical Pixels (0072,0104) US 0002 2560
> Number of Horizontal Pixels (0072,0106) US 0002 2048
> Display Environment Spatial Position (0072,0108) FD 0020 0.5\1.0\1.0\0.0
> Screen Minimum Grayscale Bit Depth (0072,010A) US 0002 0008H
> Application Maximum Repaint Time (0072,010E) US 0004 0064H
%enditem
%endseq

C-FIND Response #3:

Nesting Attribute Tag VR VL (hex) Value
Affected SOP Class UID (0000,0002) UI 0018 1.2.840.10008.5.1.4.38.2
Command Field (0000,0100) US 0002 8020H [C-FIND-RSP]
Message ID Being Responded To (0000,0120) US 0002 0010H
Data Set Type (0000,0800) US 0002 0102H
Status (0000,0900) US 0002 FF00H [Pending]
SOP Class UID (0008,0016) UI 0018 1.2.840.10008.5.1.4.38.1
SOP Instance UID (0008,0018) UI 002a 1.2.840.113986.2.664566.21121125.85669.967
Hanging Protocol Name (0072,0002) SH 0010 Chest X-ray_LGon
Hanging Protocol Description (0072,0004) LO 003e Prior and Current Lateral of Chest X-ray for two screen system
Hanging Protocol Level (0072,0006) CS 000c SINGLE_USER
Hanging Protocol Creator (0072,0008) LO 0012 Dr. Leia Gonzales
Hanging Protocol Creation DateTime (0072,000A) DT 000e 20030822101100
Hanging Protocol Definition Sequence (0072,000C) SQ ffffffff
%item
> Modality (0008,0060) CS 0002 DX
> Anatomic Region Sequence (0008,2218) SQ ffffffff
%item
>> Code Value (0008,0100) SH 0008 T-D3000
>> Coding Scheme Designator (0008,0102) SH 0004 SRT
>> Code Meaning (0008,0104) LO 0006 Chest
%enditem
%endseq
> Procedure Code Sequence (0008,1032) SQ 0000
> Laterality (0020,0060) CS 0000
> Reason for Requested Procedure Code Sequence (0040,100A) SQ 0000
%enditem
%endseq
Hanging Protocol User Identification Code Sequence (0072,000E) SQ 0000
%item
> Code Value (0008,0100) SH 0004 Lgon
> Coding Scheme Designator (0008,0102) SH 0008 99Local
> Coding Scheme Version (0008,0103) SH 0004 v40a
> Code Meaning (0008,0104) LO 000c log-in name
%enditem
%endseq
Number of Priors Referenced (0072,0014) US 0002 1
Number of Screens (0072,0100) US 0002 0002H
Nominal Screen Definition Sequence (0072,0102) SQ ffffffff
%item
> Number of Vertical Pixels (0072,0104) US 0002 1280
> Number of Horizontal Pixels (0072,0106) US 0002 1024
> Display Environment Spatial Position (0072,0108) FD 0020 0.0\1.0\0.5\0.0
> Screen Minimum Grayscale Bit Depth (0072,010A) US 0002 0008H
> Application Maximum Repaint Time (0072,010E) US 0004 0064H
%enditem
%item
> Number of Vertical Pixels (0072,0104) US 0002 1280
> Number of Horizontal Pixels (0072,0106) US 0002 1024
> Display Environment Spatial Position (0072,0108) FD 0020 0.5\1.0\1.0\0.0
> Screen Minimum Grayscale Bit Depth (0072,010A) US 0002 0008H
> Application Maximum Repaint Time (0072,010E) US 0004 0064H
%enditem
%endseq

C-FIND Response #4:

Nesting Attribute Tag VR VL (hex) Value
Affected SOP Class UID (0000,0002) UI 0018 1.2.840.10008.5.1.4.38.2.
Command Field (0000,0100) US 0002 8020H [C-FIND-RSP]
Message ID Being Responded To (0000,0120) US 0002 0010H
Data Set Type (0000,0800) US 0002 0101H
Status (0000,0900) US 0002 0000H [Success]

V.6 Display Set Patient Orientation Example

For Display Set Patient Orientation (0072,0700) with value “A\F”, the application interpreting the Hanging Protocol will arrange sagittal images oriented with the patient’s anterior toward the right side of the image box, and the patient’s foot will be toward the bottom of the image box. An incoming sagittal MRI image as shown in Figure V.6-1 will require a horizontal flip before display in the image box.

[pic]

Figure V.6-1 Display Set Patient Orientation Example