Display Sets Sequence Attribute
| Tag | (0072,0200) |
|---|---|
| Type | Required (1) |
| Keyword | DisplaySetsSequence |
| Value Multiplicity | 1 |
| Value Representation | Sequence (SQ) |
Sequence that describes one or more display sets used to present the Image Sets defined in the Image Sets Sequence (0072,0020).
One or more Items shall be included in this Sequence.
See Section C.23.3.1.
Section C.23.3.1
C.23.3.1 Hanging Protocol Display Module Attribute Descriptions
The Attributes of a Display Sets Sequence (0072,0200) Item shall be applied to the image set represented by the value of Image Set Number (0072,0032) in the following order:
-
Filter Operations Sequence
-
Reformatting
-
Sorting Operations Sequence
-
Presentation Intent
C.23.3.1.1 Filter Operations Sequence
The Items in the Filter Operations Sequence (0072,0400) determine which subset of the images in the identified Image Set are to be displayed in the associated Display Set image boxes. If there are multiple Items in the Filter Operations Sequence (0072,0400), the filter operations shall be applied in Item order, and the output of the preceding filter shall serve as the input to the succeeding filter (i.e., an AND operation). See Section C.23.4.2.1.1 and Section C.23.4.2.1.2 for additional details on matching strings and coded values.
When Filter-by Category (0072,0402) has a value of IMAGE_PLANE, Selector Attribute VR (0072,0050) shall have a value of "CS", and abstract Enumerated Values shall be used for the value of the associated Selector CS Value (0072,0062) Attribute, which may be computed from the values of Image Orientation (Patient) (0020,0037) or Patient Orientation (0020,0020).
Enumerated Values:
- TRANSVERSE
-
- CORONAL
-
- SAGITTAL
-
- OBLIQUE
-
The MEMBER_OF and NOT_MEMBER_OF values of Filter-by Operator (0072,0406) are then applicable.
Note
Cross-sectional images do not normally contain a categorical description of the image plane, but rather only a patient-relative row and column direction cosines that are unit vectors. The category of image plane can be determined first by categorizing the row and column major directions (or detecting if the orientation is oblique according to a pre-specified threshold), and then using those categories to select a plan category.
The following pseudo-code can be used to determine the major axis (R or L, A or P, H or F) from a single direction cosine that is an (x,y,z) tuple (as defined in Section C.7.6.2.1.1):
-
if (abs(x) > threshold)
-
axis = "RL"
-
-
else if (abs(y) > threshold)
-
axis = "AP"
-
-
else if (abs(z) > threshold)
-
axis = "HF"
-
-
else
-
is OBLIQUE
-
Having determined the major axis of the row and column, the category of plane can be obtained from a table lookup:
|
Column |
Row |
||
|---|---|---|---|
|
|
RL |
AP |
HF |
|
RL |
|
TRANSVERSE |
CORONAL |
|
AP |
TRANSVERSE |
|
SAGITTAL |
|
HF |
CORONAL |
SAGITTAL |
|
Alternatively, one can obtain a single vector that is the normal to the orientation (cross product of the row and column unit vectors), then find which of the x, y and z components has the maximum absolute value that is above threshold; if x then SAGITTAL, if y then CORONAL, if z then TRANSVERSE; if all of the components are below threshold then the orientation is OBLIQUE.
Since it is also necessary to determine whether or not to flip or rotate the image into the preferred orientation (as specified by Display Set Patient orientation (0072,0700)) for the category of plane (e.g., sagittals are normally viewed with row direction posteriorly and column direction towards the feet), the categorical row and column direction to use can be obtained as above, additional accounting for the sign of the direction cosine, e.g.:
-
if x < 0 then orientationX = "R" else orientationX = "L"
-
if y < 0 then orientationY = "A" else orientationY = "P"
-
if z < 0 then orientationZ = "F" else orientationZ = "H"
-
if (abs(x) > threshold)
-
orientation = orientationX
-
-
…
An application that is applying a Hanging Protocol Instance shall support any value for Selector Attribute (0072,0026). The Image Set Selector Usage Flag (0072,0024) specifies whether or not the image is included in the filter output when the Attribute or value identified by Selector Attribute (0072,0026) is not available in an image. The Attributes of the Hanging Protocol Selector Attribute Context Macro specify whether Selector Attribute (0072,0026) is contained in a Sequence, Functional Group Sequence, or Private Group.
Note
-
The following Attributes from image IODs are examples of some possible values for Selector Attribute (0072,0026) of Filter Operations Sequence (0072,0400). This is not a complete list:
-
Value 3 of Image Type (0008,0008) or Frame Type (0008,9007)
-
Anatomic Region Sequence (0008,2218)
-
Pixel Presentation (0008,9205)
-
Volume Based Calculation Technique (0008,9207)
-
Acquisition Contrast (0008,9209)
-
Contrast/Bolus Agent (0018,0010)
-
Body Part Examined (0018,0015)
-
Scanning Sequence (0018,0020)
-
Intervention Drug Start Time (0018,0035)
-
Echo Time (0018,0081)
-
Echo Number(s) (0018,0086)
-
Protocol Name (0018,1030)
-
Contrast/Bolus Start Time (0018,1042)
-
Contrast/Bolus Stop Time (0018,1043)
-
Trigger Time (0018,1060)
-
Image Trigger Delay (0018,1067)
-
Radiopharmaceutical Start Time (0018,1072)
-
Radiopharmaceutical Stop Time (0018,1073)
-
Trigger Window (0018,1094)
-
View Position (0018,5101)
-
Echo Pulse Sequence (0018,9008)
-
Phase Contrast (0018,9014)
-
Effective Echo Time (0018,9082)
-
Laterality (0020,0060)
-
Image Laterality (0020,0062)
-
Slice Location (0020,1041)
-
View Code Sequence (0054,0220)
-
-
For a multi-frame image set, it is the responsibility of the application to apply the filter operations to individual frames within a multi-frame Image Instance in the image set, versus multiple single-frame Image Instances in the image set that represent individual frames.
C.23.3.1.2 Sorting Operations Sequence
The Items in the Sorting Operations Sequence (0072,0600) define the order in which the images resulting from the filter and reformat operations on the Image Set are to be displayed in the associated Image Boxes of the Display Set. The sorting criteria may include the value of a numeric, date, or time Attribute that is expected to be present in each of the image objects in the filtered Image Set, and/or an abstract sorting category. A sorting direction shall be associated with each sorting criterion. If a textual Attribute is used for sorting, then the INCREASING sorting direction indicates alphabetical order, and DECREASING indicates reverse alphabetical order.
If a Code Sequence Attribute is used for sorting, then Code Meaning (0008,0104) shall be sorted alphabetically. If a string numeric Attribute is used for sorting (VR of IS or DS), then sorting shall be on the numeric value, and padding shall be ignored. When sorting by date or time Attribute, then sorting shall be on the temporal value, not the alphabetic string.
If there are multiple Items in the Sorting Operations Sequence (0072,0600), then the sorting operations shall be applied in Item order. The least rapidly varying Attribute for the sorting operation shall be the first Item in the Sequence.
Note
For example, a Sorting Operations Sequence (0072,0600) with two Items:
-
Item #1: (0018,5101) View Position, INCREASING
-
Item #2: (0008,0020) Study Date, INCREASING
results in the following order, based on these Attribute values in the image objects:
|
View Position (0018,5101) |
Study Date (0008,0020) |
|---|---|
|
AP |
20030201 |
|
AP |
20030501 |
|
LL |
20020705 |
|
LL |
20030102 |
|
RL |
20030101 |
|
RL |
20030201 |
When the Sort-by Category (0072,0602) is used with a value of ALONG_AXIS, such as for CT, MR or other cross-sectional image sets, the sorting operation is computed from the values Image Position (Patient) (0020,0032) and Image Orientation (Patient) (0020,0037) in the image objects.
For the image set to be displayed, a "dominant axis" of the set shall be determined. The dominant axis is the normal to Image Orientation (Patient) (0020,0037) (assuming all selected images are parallel), computed as the dot product in a right-handed coordinate system (see Section C.7.6.2.1.1). The INCREASING direction for ALONG_AXIS of the image set shall be in the positive direction along the dominant axis. The DECREASING direction shall be in the negative direction along that axis.
When the Sort-by Category (0072,0602) is used with a value of BY_ACQ_TIME, the sorting operation is computed from appropriate values in the image objects (e.g., Frame Acquisition DateTime, Acquisition Time, Content Time, Acquisition DateTime), since the specific Attribute used may vary from one Image Instance or SOP Class to another, yet the Hanging Protocol Instance may be generally applicable.
An application that is applying a Hanging Protocol Instance shall support any value for Selector Attribute (0072,0026), provided that it is present in the referenced Image Set. The Attributes of the Hanging Protocol Selector Attribute Context Macro specify whether Selector Attribute (0072,0026) is contained in a Sequence, Functional Group Sequence or Private Group.
Note
-
The following Attributes from image IODs are examples of some possible values for Selector Attribute (0072,0026) of Sorting Operations Sequence (0072,0600). This is not a complete list:
-
Acquisition DateTime (0008,002A)
-
Acquisition Time (0008,0032)
-
Echo Time (0018,0081)
-
Echo Number(s) (0018,0086)
-
Trigger Time (0018,1060)
-
View Position (0018,5101)
-
Effective Echo Time (0018,9082)
-
Acquisition Number (0020,0012)
-
Instance Number (0020,0013)
-
Slice Location (0020,1041), although Sort-by Category (0072,0602) with value ALONG_AXIS may be more reliable
-
Trigger Delay Time (0020,9153)
-
Stage Number (0008,2122)
-
View Number (0008,2128)
-
-
For a multi-frame image set, it is the responsibility of the application to apply the sorting operations to individual frames within a multi-frame Image Instance in the image set, versus multiple single-frame Image Instances in the image set that represent individual frames.
C.23.3.1.3 Blending Operation Type
A Blending Operation Type (0072,0500) of COLOR implies that the filtered selected image set contains two sets of images appropriate for blending, such as CT and PET images defined in the same Frame of Reference or associated by a spatial registration object. The decision as to which subset are the underlying images and which subset are the superimposed images is left to the discretion of the display application. There is no mechanism to explicitly specify the two subsets.
The relative opacity and color-related aspects of blending are not specified by the Hanging Protocol, and are left to the discretion of the application.
C.23.3.1.4 Presentation Intent Attributes
The Attributes that indicate the presentation intent for each Display Set of a Hanging Protocol Instance are: Display Set Patient Orientation (0072,0700), VOI Type (0072,0702), Pseudo-color Type (0072,0704), Show Grayscale Inverted (0072,0706), Show Image True Size Flag (0072,0710), Show Graphic Annotation Flag (0072,0712), Show Patient Demographics Flag (0072,0714), and Show Acquisition Techniques Flag (0072,0716).
-
If one Presentation State Instance is defined for the images that are to be displayed, then it shall be applied.
-
If more than one Presentation State Instance is defined for the images that are to be displayed, then the presentation intent Attributes, if present, shall be used to select the closest matching Presentation State Instance to apply (for example, matching VOI Type (0072,0702) in the Hanging Protocol Instance with Window Center & Width Explanation in the Presentation State Instance). Otherwise, the application shall determine which Presentation State Instance to apply.
-
If no Presentation State Instance is defined for the images that are to be displayed, then the presentation intent Attributes, if present, shall be applied (for example, matching VOI Type (0072,0702) in the Hanging Protocol Instance with Window Center & Width Explanation in the Image). Otherwise, the display related information in the Image Instances shall be applied.
The intent of VOI Type (0072,0702) is to support generic intensity window settings for the Display Sets in a Hanging Protocol, such as lung, soft tissue, or bone for chest CT. It is expected for most other modalities that the window/center or VOI LUT values, if not provided in a Presentation State Instance, would be provided in the Image Instance rather than by intent in a Hanging Protocol Instance.
The value of Show Grayscale Inverted (0072,0706) shall override any such intent expressed in the images or associated Presentation States to which the Hanging Protocol is applied.
Note
-
For example, an image may have a MONOCHROME2 Photometric Interpretation (0028,0004) and no Presentation LUT Shape (2050,0020), which implies that maximum values are displayed with maximum available luminance, but the presence of a Show Grayscale Inverted (0072,0706) value of YES in the Hanging Protocol requires maximum values to be displayed with minimum available luminance.
-
For example, an image may have an applicable Presentation State with a Presentation LUT Shape (2050,0020) of IDENTITY, which implies that maximum values are displayed with maximum available luminance, but the presence of a Show Grayscale Inverted (0072,0706) value of YES in the Hanging Protocol requires maximum values to be displayed with minimum available luminance.
-
For example, an image may have an applicable Presentation State with a Presentation LUT, in which case the minimum possible LUT output value (i.e., 0) will be interpreted as maximum available luminance if the value of Show Grayscale Inverted (0072,0706) is YES.
The intent of Display Set Patient Orientation (0072,0700) is to describe the preferred image rotation and/or flip for presentation within an image box. Each of the two values shall be an anatomic direction designated by the capital letters: A (anterior), P (posterior), R (right), L (left), H (head), F (foot), or X (unspecified). Each value of the orientation Attribute shall contain at least one of these characters. If refinements in the orientation descriptions are to be specified, then they shall be designated by one or two additional letters in each value. Within each value, the letters shall be ordered with the principal orientation designated in the first character. If the value "X" is used for one of the values, the patient direction for that value is not defined.
The first value is the patient direction to be oriented at the right side of the image box for each image. The second value is the patient direction to be positioned at the bottom of the image box for each image. The application shall use the patient orientation information of each image (if available) to compute the best rotate and/or flip operation to be applied within the display set. If the patient orientation of an image is not defined, then this Attribute shall be ignored.