Sup 243 - Label Map Segmentation DICOM Standards Committee - Working Group 6 - Base Standard

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2017 NEMA Status: Final Text 2024/09/14 This supplement is prepared pursuant to work item: 2023-10-B This Supplement describes addition of a Label Map Segmentation IOD to DICOM to encode classification of entities. Currently, the DICOM standard supports an IOD and SOP Class for pixel- or voxel-based segmentation encoding (as distinct from the representation of segmented objects as surfaces in the surface segmentation and encapsulated 3D object IODs and SOP Classes), in which each segmented property is represented as a binary bit plane (or an 8 bit probabilistic or occupancy value). While this allows for overlapping of segments, it is inefficient and difficult to encode large numbers of non-overlapping segmentations, as they require non-trivial processing both to extract from the bit plane encoded data, to assure there is no overlap, and to convert to the label map form that is very commonly used internally and persistently for clinical applications. The current DICOM bit-plane-based segmentation methods have proven to be awkward both for 3D cross-sectional imaging applications when there are very large numbers of slices and/or structures, and for whole slide microscopy imaging, when there are very large numbers of tiles and/or property classes. They are also typically large and sparse and should compress well but there are very few single bit compression schemes supported by the standard and they do not do well with these types of images. This Supplement defines a label map segmentation enhanced multi-frame IOD that specifies a data structure that provides, for each pixel or voxel in 2D, 3D or tiled pyramidal space, an index value conveying the non-overlapping segment for each pixel. Existing data elements for describing segmentations are reused where appropriate. Bit depth is sufficient (8, 16) to encode large numbers of segments but allow for more compact encoding. The existing palette color photometric interpretation may be used (instead of monochrome) if colors are to be suggested, to leverage the widespread implementations in toolkits, and to allow for the use of existing lossless compression schemes. Segment properties are conveyed in the existing segment description structure so as to be compatible with the existing bit plane segment descriptions. Re-using the segment description does not prevent the use of separately encoded or well-known DICOM color palette objects. The scope is confined to label maps for "classes" (what "class" a segment represents) but not "instances' (which "instance" of a "class" is represented), where classes and instances are separately communicated by the pixel value (e.g., if one wants to individually identify nuclei rather than treat them all as being of one class). This might be the subject of a future extension. The scope is confined to a single label map, which does not allow for overlap of different segments. If overlapping of multiple label maps is required, separate SOP Instances may be created. Issues related to the efficient representation (or avoidance) of the Per-Frame Functional Group Sequence (in which, for every frame, the Referenced Segment Number is specified) are out of scope, and may be addressed in a separate Supplement or CP if necessary. PS3.3 for reference: Segment A part of a whole, such as the classification of pixels in an image. Amend PS3.3 as follows (changes to existing text are bold and underlined for additions and struckthrough for removals):

Composite Information Object Modules Overview - More Images

IODs Modules	Seg
Patient	M
Clinical Trial Subject	U
General Study	M
Patient Study	U
Clinical Trial Study	U
General Series	M
Clinical Trial Series	U
Segmentation Series	M
Frame of Reference	C
General Equipment	M
Enhanced General Equipment	M
Acquisition	U
Multi-Resolution Pyramid	U
General Image	M
General Reference	U
Microscope Slide Layer Tile Organization	C
Image Pixel	M
Palette Color Lookup Table	C
Multi-frame Functional Groups	M
Multi-frame Dimension	M
Specimen	U
Segmentation Image	M
Common Instance Reference	C
ICC Profile	C
SOP Common	M
Frame Extraction	C

The Segmentation IOD specifies a multi-frame image representing a classification of pixels in one or more referenced images. Segmentations are either binary, or fractional, or label map. If the referenced images have a defined Frame of Reference, the Segmentation Instance shall have the same Frame of Reference and is not required to have the same spatial sampling or extent as the referenced images. If the referenced image does not have a defined Frame of Reference, the Segmentation Instance shall have the same spatial sampling and extent as the referenced image. The Segmentation IOD does not include the full set of acquisition parameters of the referenced images, e.g., cardiac phase. An application rendering or processing the sSegmentation Instance may need to access the referenced images for such information. The Segmentation IOD is used in two SOP Classes as defined in PS3.4 Storage Service Class, a SOP Class for storage of BINARY and FRACTIONAL segmentations, and a SOP Class for storage of LABELMAP segmentations. These are distinguished by their SOP Class UID and by the Enumerated Value of the Segmentation Type (0062,0001) of the .

This IOD uses the E-R Model in Section A.1.2 , with only the Image IE below the Series IE.

specifies the Modules of the Segmentation IOD.

Segmentation IOD Modules

IE	Module	Reference	Usage
Patient	Patient	C.7.1.1	M
	Clinical Trial Subject	C.7.1.3	U
Study	General Study	C.7.2.1	M
	Patient Study	C.7.2.2	U
	Clinical Trial Study	C.7.2.3	U
Series	General Series	C.7.3.1	M
	Segmentation Series	C.8.20.1	M
	Clinical Trial Series	C.7.3.2	U
Frame of Reference	Frame of Reference	C.7.4.1	C - Required if Derivation Image Functional Group (C.7.6.16.2.6) is not present. May be present otherwise.
Equipment	General Equipment	C.7.5.1	M
	Enhanced General Equipment	C.7.5.2	M
Acquisition	General Acquisition	C.7.10.1	U
Multi-Resolution Pyramid	Multi-Resolution Pyramid	C.7.11.1	U
Image	General Image	C.7.6.1	M
	General Reference	C.12.4	U
	Microscope Slide Layer Tile Organization	C.8.12.14	C - Required if Dimension Organization Type (0020,9311) is present with a value of TILED_FULL. May be present otherwise.
	Image Pixel	C.7.6.3	M
	Segmentation Image	C.8.20.2	M
	Multi-frame Functional Groups	C.7.6.16	M
	Multi-frame Dimension	C.7.6.17	M
	Palette Color Lookup Table	C.7.9	C - Required if Photometric Interpretation (0028,0004) has a value of PALETTE COLOR.
	Specimen	C.7.6.22	U
	Common Instance Reference	C.12.2	C - Required if Derivation Image Functional Group (C.7.6.16.2.6) is present.
	ICC Profile	C.11.15	C - Required if Photometric Interpretation (0028,0004) has a value of PALETTE COLOR.
	SOP Common	C.12.1	M
	Frame Extraction	C.12.3	C - Required if the SOP Instance was created in response to a Frame-Level retrieve request

The Specimen Identification Module (Retired) was previously included in this IOD but has been retired, and its functionality replaced by the Specimen Module. See PS3.3-2008.

The VOI LUT Module shall not be present. The Modality LUT Module shall not be present. The Overlay Plane Module shall not be present. Pixel Padding Value (0028,0120) shall not be present if Segmentation Type (0062,0001) is not LABELMAP. Pixel Padding Value (0028,0010) may be used to indicate that a particular segment is background if Segmentation Type (0062,0001) is LABELMAP; see Pixel Padding Value (0028,0120) in . Pixel Padding Range Limit (0028,0121) shall not be present. For Purpose of Reference Code Sequence (0040,A170) within Source Instance Sequence (0042,0013) in the General Reference Module D shall be used.

specifies the use of the Functional Group Macros used in the Multi-frame Functional Groups Module for the Segmentation IOD.

Segmentation Functional Group Macros

Functional Group Macro	Section	Usage
Pixel Measures	C.7.6.16.2.1	C - Required if Derivation Image Functional Group (C.7.6.16.2.6) is not present and the Frame of Reference is defined in the patient-relative Reference Coordinate System. May be present otherwise if the Frame of Reference is defined in the patient-relative Reference Coordinate System. See
Plane Position (Patient)	C.7.6.16.2.3	C - Required if Derivation Image Functional Group (C.7.6.16.2.6) is not present and the Frame of Reference is defined in the patient-relative Reference Coordinate System. May be present otherwise if the Frame of Reference is defined in the patient-relative Reference Coordinate System. See
Plane Orientation (Patient)	C.7.6.16.2.4	C - Required if Derivation Image Functional Group (C.7.6.16.2.6) is not present and the Frame of Reference is defined in the patient-relative Reference Coordinate System. May be present otherwise if the Frame of Reference is defined in the patient-relative Reference Coordinate System. See
Plane Position (Slide)	C.8.12.6.1	C - Required if Derivation Image Functional Group (C.7.6.16.2.6) is not present and the Frame of Reference is defined in the Slide Coordinate System and Dimension Organization Type (0020,9311) is not TILED_FULL. May be present otherwise if the Frame of Reference is defined in the Slide Coordinate System. See .
Derivation Image	C.7.6.16.2.6	C - Required if Pixel Measures (C.7.6.16.2.1) or either Plane Position (Patient) (C.7.6.16.2.3) or Plane Orientation (Patient) (C.7.6.16.2.4) (if the Frame of Reference is defined in the patient-relative Reference Coordinate System), or Plane Position (Slide) (C.8.12.6.1) (if the Frame of Reference is defined in the Slide Coordinate System) Functional Groups are not present. May be present otherwise. See
Frame Content	C.7.6.16.2.2	M
Segmentation	C.8.20.3.1	C - Required if Dimension Organization Type (0020,9311) is not TILED_FULL and Segmentation Type (0062,0001) is not LABELMAP.

The Plane Position (Slide), Frame Content and Segmentation Macros are Type C, which allows the Per-Frame Functional Group Sequence (5200,9230) to be entirely omitted in those cases in which there are no other Per-Frame Functional Group Macros with content (i.e., the Frame Content Macro is empty or absent).

When a Frame of Reference UID is present the Ssegment shall be specified within that coordinate system, using the Pixel Measures and either the Plane Position (Patient) and Plane Orientation (Patient), or the Plane Position (Slide) Functional Groups. Since this defines the spatial relationship of the Ssegment, the size of the segmentation frames need not be the same size, or resolution, as the image data used to generate the segment data. The Derivation Image Functional Group may also be present, to specify on which images the segmentation was actually performed (since there may be others in the same Frame of Reference that are spatially co-located, but were not used to perform the segmentation). If the Frame of Reference UID is not present, each pixel of the segmentation shall correspond to a pixel in a referenced image, using the Derivation Image Functional Group. Hence, the rows and columns of each referenced image will match the segmentation image. If both the Frame of Reference UID and the Derivation Image Functional Group are present, the segmentation and referenced image pixels need not correspond. The value of Purpose of Reference Code Sequence (0040,A170) in the Derivation Image Macro shall be (121322, DCM, "Source Image for Image Processing Operation"). The value of Derivation Code Sequence (0008,9215) shall be (113076, DCM, "Segmentation"). Non-image source Instances used during segmentation, such as Real World Value maps, can be described in the top level Data Set in the Source Instance Sequence (0042,0013) of the General Reference Module and are implied to have been used for the derivation of all frames. I.e., there is no mechanism for selectively specifying on a per-frame basis which non-Image Instances were used. Real World Value Map Instances already contain a means of selectively applying different scale factors to different frames.

This section describes the specific Modules for the Segmentation IOD.

specifies the Attributes of the .

Segmentation Series Module Attributes

Attribute Name	Tag	Type	Attribute Description
Modality	(0008,0060)	1	Type of device, process or method that created the Instances in this Series. SEG
Series Number	(0020,0011)	1	A number that identifies this Series.
Referenced Performed Procedure Step Sequence	(0008,1111)	1C	Uniquely identifies the Performed Procedure Step SOP Instance to which the Series is related. Only a single Item shall be included in this Sequence. Required if a Performed Procedure Step SOP Class was involved in the creation of this Series.
>Include Table 10-11 "SOP Instance Reference Macro Attributes"

specifies the Attributes of the .

Segmentation Image Module Attributes

Attribute Name	Tag	Type	Attribute Description
Image Type	(0008,0008)	1	Image identification characteristics. Value 1 shall be DERIVED. Value 2 shall be PRIMARY. No other values shall be present.
Include Table 10-12 "Content Identification Macro Attributes"
Samples Per Pixel	(0028,0002)	1	Number of samples (planes) in this image. 1
Photometric Interpretation	(0028,0004)	1	Specifies the intended interpretation of the pixel data. MONOCHROME2 MONOCHROME2 PALETTE COLOR
Pixel Representation	(0028,0103)	1	Data representation of pixel samples. 0
Bits Allocated	(0028,0100)	1	Number of bits allocated for each pixel sample. See . 1 8 8 16
Bits Stored	(0028,0101)	1	Number of bits stored for each pixel sample. See . 1 8 8 16
High Bit	(0028,0102)	1	Most significant bit for pixel sample data. See . 0 7 7 15
Lossy Image Compression	(0028,2110)	1	Specifies whether an Image has undergone lossy compression (at a point in its lifetime), or is derived from lossy compressed images. 00 Image has NOT been subjected to lossy compression. 01 Image has been subjected to lossy compression. Once this value has been set to "01" it shall not be reset. See and Section C.7.6.1.1.5.
Lossy Image Compression Ratio	(0028,2112)	1C	Describes the approximate lossy compression ratio(s) that have been applied to this image. See Section C.7.6.1.1.5.2 . Required if present in the source images or this IOD Instance has been compressed.
Lossy Image Compression Method	(0028,2114)	1C	A label for the lossy compression method(s) that have been applied to this image. See Section C.7.6.1.1.5.1 . Required if present in the source images or this IOD Instance has been compressed. See .
Segmentation Type	(0062,0001)	1	The type of encoding used to indicate the presence of the segmented property at a pixel/voxel location. BINARY FRACTIONAL LABELMAP See .
Segmentation Fractional Type	(0062,0010)	1C	For fractional segmentation encoding, the meaning of the fractional value. Required if Segmentation Type (0062,0001) is FRACTIONAL. See for Enumerated Values.
Maximum Fractional Value	(0062,000E)	1C	Specifies the value that represents a probability of 1 or complete occupancy. There shall be no values in Pixel Data (7FE0,0010) greater than this value. Required if Segmentation Type (0062,0001) is FRACTIONAL.
Segments Overlap	(0062,0013)	3	Whether or not any Ssegments in this Instance overlap. I.e., whether or not any pixel is or might be in more than one Ssegment. YES Some Ssegments overlap UNDEFINED Some Ssegments might overlap NO No Ssegments overlap See . If present, shall be NO if Segmentation Type (0062,0001) is LABELMAP. If the value is NO, then a receiving application to which this matters can be assured that no Ssegments overlap and does not need to check every pixel. If the value is UNDEFINED or YES, or the Attribute is absent, then a receiving application might need to check every pixel in every Ssegment.
Segment Sequence	(0062,0002)	1	Describes the Ssegments that are contained within the data. One or more Items shall be included in this Sequence. The Items of this Sequence are not required to be in any particular order, i.e., are not required to be ordered by Segment Number (0062,0004).
>Include
>Segment Algorithm Name	(0062,0009)	1C	The name(s) of algorithm(s) used to generate the Ssegment. Required if Segment Algorithm Type (0062,0008) is not MANUAL.
>Segmentation Algorithm Identification Sequence	(0062,0007)	3	A description of how this Ssegment was derived. Algorithm Name (0066,0036) within this Sequence may be identical to Segment Algorithm Name (0062,0009). One or more Items are permitted in this Sequence. Previously, the Segment Surface Generation Algorithm Identification Code Sequence (0066,002D) was used, but it has been replaced in this Module, since not all segmentation algorithms involve surface generation. See PS3.3-2016d.
>>Include Table 10-19 "Algorithm Identification Macro Attributes"			B.
>Recommended Display Grayscale Value	(0062,000C)	3	A default single gray unsigned value in which it is recommended that the maximum pixel value in this Ssegment be rendered on a monochrome display. The units are specified in P-Values from a minimum of 0000H (black) up to a maximum of FFFFH (white). The maximum P-Value for this Attribute may be different from the maximum P-Value from the output of the Presentation LUT, which may be less than 16 bits in depth.
>Recommended Display CIELab Value	(0062,000D)	3	A default triplet value in which it is recommended that Ssegment be rendered on a color display. The units are specified in PCS-Values, and the value is encoded as CIELab. See Section C.10.7.1.1. Shall not be present if Segmentation Type (0062,0001) is LABELMAP and Photometric Interpretation (0028,0004) is PALETTE COLOR.

As a consequence of the eEnumerated Values for Bits Allocated and, Bits Stored, and High Bit Attribute values, single bit pixels shall be packed 8 to a byte as defined by the encoding rules in .

If Lossy Image Compression (0028,2110) in any of the source images is "01", the value shall be "01" for the Segmentation Instance. The process of segmentation itself is defined not to be lossy compression, even though it involves loss. If the Segmentation Instance is encoded using a lossy compression Transfer Syntax, then the value shall be set to "01". It is not advisable to lossy compress a Segmentation SOP Instance. In particular, a binary BINARY or LABELMAP Ssegmentation Instances should not be lossy compressed.

A Segmentation Type (0062,0001) of BINARY indicates that the segmented property is present with a value of 1 and absent with a value of 0.

For a Segmentation Type (0062,0001) of FRACTIONAL the segmented property is defined as a value from zero to the Maximum Fractional Value (0062,000E). A FRACTIONAL segmentation shall be further specified via Segmentation Fractional Type (0062,0010). PROBABILITY Defines the probability, as a ratio of the pixel value to the Maximum Fractional Value, that the segmented property occupies the spatial area defined by the voxel. OCCUPANCY Defines the proportion of the pixel volume occupied by the segmented property as the ratio of the pixel value to the Maximum Fractional Value.

A Segmentation Type (0062,0001) of LABELMAP indicates that the presence of the segmented property is conveyed by the integer value of the Pixel Data (7FE0,0010), which is one of the values of Segment Number (0062,0004). BinaryBINARY Segmentation Instances may be transformed into or from "label maps", in which each pixel contains a coded value that indicates the segment, rather than the Segmentation IOD representation that encodes separate bit planes for each segment. This conversion is facilitated by knowing whether or not any Ssegment bitplanes overlap. By definition, each pixel value in a single LABELMAP Segmentation Instance can only represent one Segment. and cannot overlap. A Segments Overlap (0062,0013) value of NO indicates that they can be converted into (or may have been converted from) a label map representation without the need to check every pixel. For a Segmentation Type (0062,0001) of LABELMAP, every pixel value actually encoded in Pixel Data (7FE0,0010) is required to be described in an Item of Segment Sequence (0062,0002). The converse is not true, in that the Segment Sequence (0062,0002) can describe Segments that are not actually present in the pixel data, e.g., to allow for re-use of a common Ssegment description across multiple instances, despite the inefficiency of encoding unused information. The need to describe every pixel value implies that the value 0, if used, will also be described, which might serve as the background.

Segment Number (0062,0004) shall be unique within each Instance. If Segmentation Type (0062,0001) is BINARY or FRACTIONAL, Segment Number (0062,0004) shall start at a value of 1, and increase monotonically by 1. When converting from LABELMAP Segmentation Instances to BINARY Segmentation Instances, care should be taken to reassign the Segment Number (0062,0004) values if necessary, such that the requirements in this section are complied with. Requirements on the ascending order of the Segment Number (0062,0004) values do not imply an ordering of the Sequence Items of any enclosing Sequence. For a Segmentation Type (0062,0001) of LABELMAP, if a value is specified in Pixel Padding Value (0028,0120), that indicates that the corresponding Segment Number is treated as background; see and . Otherwise, no particular value of Segment Number is deemed to be treated specially as background.

The following sections contain Functional Group Macros specific to the Segmentation IOD. The Attribute descriptions in the Functional Group Macros are written as if they were applicable to a single frame (i.e., the Macro is part of the Per-Frame Functional Groups Sequence). If an Attribute is applicable to all frames (i.e., the Macro is part of the Shared Functional Groups Sequence) the phrase "this frame" in the Attribute description shall be interpreted to mean "for all frames".

specifies the Attributes of the .

Segmentation Macro Attributes

Attribute Name	Tag	Type	Attribute Description
Segment Identification Sequence	(0062,000A)	1	Identifies the characteristics of this frame. Only a single Item shall be included in this Sequence.
>Referenced Segment Number	(0062,000B)	1	Uniquely identifies the Ssegment described in Segment Sequence (0062,0002) by reference to Segment Number (0062,0004). Referenced Segment Number (0062,000B) shall not be multi-valued.

The following sections contain Macros specific to the Segmentation IOD.

specifies the Attributes of the .

Segment Description Macro Attributes

Attribute Name	Tag	Type	Attribute Description
Segment Number	(0062,0004)	1	Identification number of the Ssegment. The value of Segment Number (0062,0004) shall be unique within the Segmentation Instance in which it is created. See .
Segment Label	(0062,0005)	1	User-defined label identifying this Ssegment. This may be the same as Code Meaning (0008,0104) of Segmented Property Type Code Sequence (0062,000F).
Segment Description	(0062,0006)	3	User-defined description for this Ssegment.
Segment Algorithm Type	(0062,0008)	1	Type of algorithm used to generate the Ssegment. AUTOMATIC calculated Ssegment SEMIAUTOMATIC calculated Ssegment with user assistance MANUAL user-entered Ssegment
Include Table 10-7b "Multiple Site General Anatomy Optional Macro Attributes"			May not be necessary if the anatomy is implicit in the Segmented Property Type Code Sequence. More than one Item in Anatomic Region Sequence (0008,2218) may be used when a region of interest spans multiple anatomical locations and there is not a single pre-coordinated code describing the combination of locations. There is no requirement that the multiple locations be contiguous.
Segmented Property Category Code Sequence	(0062,0003)	1	Sequence defining the general category of the property the Ssegment represents. Only a single Item shall be included in this Sequence.
>Include Table 8.8-1 "Code Sequence Macro Attributes"			B.
Segmented Property Type Code Sequence	(0062,000F)	1	Sequence defining the specific property the Ssegment represents. "Property" is used in the sense of meaning "what the segmented voxels represent", whether it be a physical or biological object, be real or conceptual, having spatial, temporal or functional extent or not. I.e., it is what the Ssegment "is" (as opposed to some feature, attribute, quality, or characteristic of it, like color or shape or size). Only a single Item shall be included in this Sequence.
>Include Table 8.8-1 "Code Sequence Macro Attributes"			B.
>Segmented Property Type Modifier Code Sequence	(0062,0011)	3	Sequence defining the modifier of the property type of this Ssegment. One or more Items are permitted in this Sequence.
>>Include Table 8.8-1 "Code Sequence Macro Attributes"			D. For Retinal Segmentation Surfaces, laterality is not typically specified.
Tracking ID	(0062,0020)	1C	A text label used for tracking a finding or feature, potentially across multiple reporting objects, over time. This label shall be unique within the domain in which it is used. Required if Tracking UID (0062,0021) is present. May or may not have the same value as Segment Label (0062,0005). Related SR Instances may exist, for example, to record measurements related to this Ssegment, but need not exist for this Attribute to be used. This Attribute will have the same value as the value of the (112039, DCM, "Tracking Identifier") Content Item in SR Instances that reference this Segment in this Segmentation Instance.
Tracking UID	(0062,0021)	1C	A unique identifier used for tracking a finding or feature, potentially across multiple reporting objects, over time. Required if Tracking ID (0062,0020) is present. Related SR Instances may exist, for example, to record measurements related to this Ssegment, but need not exist for this Attribute to be used. This Attribute will have the same value as the value of the (112040, DCM, "Tracking Unique Identifier") Content Item in SR Instances that reference this Segment in this Segmentation Instance.
Definition Source Sequence	(0008,1156)	3	Instances containing the source of the Segment information. Only a single Item is permitted in this Sequence.
>Include Table 10-11 "SOP Instance Reference Macro Attributes".
>Referenced ROI Number	(3006,0084)	1C	The value of ROI Number (3006,0022) in the referenced SOP Instance that identifies the ROI that is the origin of the Segment information. Required if Referenced SOP Class UID (0008,1150) is RT Structure Set Storage ("1.2.840.10008.5.1.4.1.1.481.3").
Include Table 10.9.3-1 "Content Creator Macro"

...

Pixel Padding Value (0028,0120) is typically used to pad grayscale images (those with a Photometric Interpretation (0028,0004) of MONOCHROME1 or MONOCHROME2), or color images with a Photometric interpretation (0028,0004) of PALETTE COLOR, to rectangular format. The native format of some images is not rectangular. It is common for devices with this format to pad the images, to the rectangular format required by the DICOM Standard, with a specific pixel value that is not contained in the native image. Further, when resampling, such as after spatial registration, padding may need to be used to fill previously non-existent pixels. Pixel Padding Value (0028,0120) and Pixel Padding Range Limit (0028,0121) are also used to identify pixels to be excluded from the rendering pipeline for other reasons, such as suppression of background air. Pixel Padding Range Limit (0028,0121) is defined in the . The "native image" is that which is being padded to the required rectangular format, e.g., the area within the circular reconstruction perimeter of a CT image, or the subset of the rectangular area that contains useful image information, i.e., which is not to be suppressed, or e.g., is that part of a pseudo-colored image that might be superimposed on top of another image. For other mechanisms, see . The Pixel Padding Value is explicitly described in order to prevent display applications from taking it into account when determining the dynamic range of an image, since the Pixel Padding Value will be outside the range between the minimum and maximum values of the pixels in the native image No pixels in the native image will have a value equal to Pixel Padding Value (0028,0120). Pixel Padding Value (0028,0120) specifies either a single value of this padding, or when combined with Pixel Padding Range Limit (0028,0121), a range of values (inclusive) that are padding. The values of Pixel Padding Value (0028,0120) and Pixel Padding Range Limit (0028,0121) shall be valid values within the constraints defined by Bits Allocated (0028,0100), Bits Stored (0028,0101), and High Bit (0028,0102). The Pixel Padding Value shall correspond to a value in the original stored pixel data, before the Modality LUT Transformation or any other transformations are applied. Pixel Padding Value (0028,0120) and Pixel Padding Range Limit (0028,0121) shall not be present when padding is performed but the pixel value used for padding does occur in the native image. If Photometric Interpretation (0028,0004) is MONOCHROME2 or PALETTE COLOR, Pixel Padding Value (0028,0120) shall be less than (closer to or equal to the minimum possible pixel value) or equal to Pixel Padding Range Limit (0028,0121). If Photometric Interpretation (0028,0004) is MONOCHROME1, Pixel Padding Value (0028,0120) shall be greater than (closer to or equal to the maximum possible pixel value) or equal to Pixel Padding Range Limit (0028,0121). When the relationship between pixel value and X-Ray Intensity is unknown, it is recommended that the following values be used to pad with black when the image is unsigned: 0 if Photometric Interpretation (0028,0004) is MONOCHROME2. 2Bits Stored - 1 if Photometric Interpretation (0028,0004) is MONOCHROME1. and when the image is signed: -2Bits Stored-1 if Photometric Interpretation (0028,0004) is MONOCHROME2. 2Bits Stored-1 - 1 if Photometric Interpretation (0028,0004) is MONOCHROME1. For projection radiography, when the relationship between pixel value and X-Ray Intensity is known (for example as defined by Pixel Intensity Relationship (0028,1040) and Pixel Intensity Relationship Sign (0028,1041)), it is recommended that a pixel value equivalent to, or rendered similarly to, air (least X-Ray absorbance) be used for padding. However, if such a value may occur in the native image, the Pixel Padding Value (0028,0120) Attribute itself should not be present. E.g., for an XRF image obtained with an image intensifier, if air is black then a padded perimeter, if any, should also appear black. Typically though, if unpadded, this area would be collimated with a circular collimator, in which case the pixels would appear natively as white (greatest X-Ray absorbance) and a circular shutter would be necessary to neutralize them as black. Whether collimated areas are detected and treated as padded, or neutralized with shutters is at the discretion of the application. See also the . The conditional requirement for the Pixel Padding Range Limit (0028,0121) in the means that it shall not be present unless Pixel Padding Value (0028,0120) is also present. The range of values to be suppressed between Pixel Padding Value (0028,0120) and Pixel Padding Range Limit (0028,0121) is specified as being inclusive, that is the values themselves as well as all values between are suppressed. When Pixel Padding Range Limit (0028,0121) is present, but not supported by a rendering application, the constraint that Pixel Padding Value (0028,0120) is closest to the "blackest" value, which is typically the most frequently occurring background pixel, will most often result in an acceptable display, permitting "backward compatibility" in the majority of cases. For Segmentations with a Segmentation Type (0062,0001) of LABELMAP, Pixel Padding Value (0028,0120) may be used to indicate that a particular pixel value is to be treated as background. Only a single pixel value is so indicated, and Pixel Padding Range Limit (0028,0121) is not used; see . Typically the Pixel Padding Value (0028,0120) will be 0, but it can be another value, or may not be specified at all. When modifying equipment changes the Pixel Padding Value in the image, it shall change the values of Pixel Padding Value (0028,0120) and Pixel Padding Range Limit (0028,0121), if present. If modifying equipment changes the Pixel Padding Values in the image to values present in the native image, the Attribute Pixel Padding Value (0028,0120) and Pixel Padding Range Limit (0028,0121) shall be removed. For example, if a CT image containing signed values from -1024 to 3191 and a Pixel Padding Value (0028,0120) of -2000 and a Rescale Intercept (0028,1052) of 0 is converted to an unsigned image with a Rescale Intercept (0028,1052) of -1024 by adding 1024 to all pixels and clipping all more negative pixels to 0, then the padding pixels will be indistinguishable from some of the modified native image pixels, and hence Pixel Padding Value (0028,0120) needs to be removed. If the modification involves lossy compression, which may result in changes to the pixel values, then the application of Pixel Padding Value (0028,0120) and Pixel Padding Range Limit (0028,0121) may result in a different appearance, and hence these Attributes may need different values also.

specifies the Attributes of the , which describe the Lookup table data for images with Palette Color photometric interpretation. When the is present in an Image IOD, the conditional requirements for the use of Palette Color Lookup Table Data (0028,1201-1203) and Segmented Palette Color Lookup Table Data (0028,1221-1223), described in , shall take precedence over the conditional requirements described in the Image Pixel Module (see Section C.7.6.3). When the is present in a Presentation State IOD, the Palette Color Lookup Table Data (0028,1201-1203) Attributes are mandatory and the Segmented Palette Color Lookup Table Data (0028,1221-1223) shall not be present. When the is present in a Color Palette IOD, either the Palette Color Lookup Table Data (0028,1201-1203) or Segmented Palette Color Lookup Table Data (0028,1221-1223) Attributes may be used. When the is present in a Color Palette IOD, the 3rd value of Palette Color Lookup Table Descriptor (0028,1101-1103) (i.e, the number of bits for each entry in the Lookup Table Data) shall be 8.

Palette Color Lookup Table Module Attributes

Attribute Name	Tag	Type	Attribute Description
Include

Palette Color Lookup Table Macro Attributes

Attribute Name	Tag	Type	Attribute Description
Red Palette Color Lookup Table Descriptor	(0028,1101)	1	Specifies the format of the Red Palette Color Lookup Table Data (0028,1201). See Section C.7.6.3.1.5 for further explanation.
Green Palette Color Lookup Table Descriptor	(0028,1102)	1	Specifies the format of the Green Palette Color Lookup Table Data (0028,1202). See Section C.7.6.3.1.5 for further explanation.
Blue Palette Color Lookup Table Descriptor	(0028,1103)	1	Specifies the format of the Blue Palette Color Lookup table Data (0028,1203). See Section C.7.6.3.1.5 for further explanation.
Palette Color Lookup Table UID	(0028,1199)	3	Palette Color Lookup Table UID. See for further explanation.
Red Palette Color Lookup Table Data	(0028,1201)	1C	Red Palette Color Lookup Table Data. Required if segmented data is NOT used in an Image IOD or Color Palette IOD, or if the IOD is a Presentation State IOD or Segmentation IOD. See Section C.7.6.3.1.6 for further explanation.
Green Palette Color Lookup Table Data	(0028,1202)	1C	Green Palette Color Lookup Table Data. Required if segmented data is NOT used in an Image IOD or Color Palette IOD, or if the IOD is a Presentation State IOD or Segmentation IOD. See Section C.7.6.3.1.6 for further explanation.
Blue Palette Color Lookup Table Data	(0028,1203)	1C	Blue Palette Color Lookup Table Data. Required if segmented data is NOT used in an Image IOD or Color Palette IOD, or if the IOD is a Presentation State IOD or Segmentation IOD. See Section C.7.6.3.1.6 for further explanation.
Segmented Red Palette Color Lookup Table Data	(0028,1221)	1C	Segmented Red Palette Color Lookup Table Data. Required if segmented data is used in an Image IOD or Color Palette IOD; shall not be present in a Presentation State IOD or Segmentation IOD. See for further explanation.
Segmented Green Palette Color Lookup Table Data	(0028,1222)	1C	Segmented Green Palette Color Lookup Table Data. Required if segmented data is used in an Image IOD or Color Palette IOD; shall not be present in a Presentation State IOD or Segmentation IOD See for further explanation.
Segmented Blue Palette Color Lookup Table Data	(0028,1223)	1C	Segmented Blue Palette Color Lookup Table Data. Required if segmented data is used in an Image IOD or Color Palette IOD; shall not be present in a Presentation State IOD or Segmentation IOD. See for further explanation.

...

...

... When the Red, Green, or Blue Palette Color Lookup Table Descriptor (0028,1101-1103) are used as part of the in the Segmentation IOD, the 3rd value of Palette Color Lookup Table Descriptor (0028,1101-1103) (i.e, the number of bits for each entry in the Lookup Table Data) shall be 8 or 16. A value of 16 indicates the Lookup Table Data will range from (0,0,0) minimum intensity to (65535,65535,65535) maximum intensity. Since the Palette Color Lookup Table Descriptor (0028,1101-1104) Attributes are multi-valued, in an Explicit VR Transfer Syntax, only one value representation (US or SS) may be specified, even though the first and third values are always by definition interpreted as unsigned. The explicit VR actually used is dictated by the VR needed to represent the second value, which will be consistent with Pixel Representation (0028,0103).

...

Amend PS3.4 as follows (changes to existing text are bold and underlined for additions and struckthrough for removals):

The SOP Classes in the Storage Service Class identify the Composite IODs to be stored. identifies Standard SOP Classes.

Standard SOP Classes

SOP Class Name	SOP Class UID	IOD Specification (defined in )	Specialization
...
Digital X-Ray Image Storage - For Presentation	1.2.840.10008.5.1.4.1.1.1.1
Digital X-Ray Image Storage - For Processing	1.2.840.10008.5.1.4.1.1.1.1.1
...
Segmentation Storage	1.2.840.10008.5.1.4.1.1.66.4
Label Map Segmentation Storage	1.2.840.10008.5.1.4.1.1.66.7
Surface Segmentation Storage	1.2.840.10008.5.1.4.1.1.66.5
...

The Digital X-Ray Image Storage - For Presentation SOP Class shall use the DX IOD with an Enumerated Value of FOR PRESENTATION for Presentation Intent Type (0008,0068). The Digital X-Ray Image Storage - For Processing SOP Class shall use the DX IOD with an Enumerated Value of FOR PROCESSING for Presentation Intent Type (0008,0068). ...

The Segmentation Storage SOP Class shall use the with an Enumerated Value of BINARY or FRACTIONAL for Segmentation Type (0062,0001). The Label Map Segmentation Storage SOP Class shall use the with an Enumerated Value of LABELMAP for Segmentation Type (0062,0001).

Amend PS3.6 as follows (changes to existing text are bold and underlined for additions and struckthrough for removals):

UID Values

UID Value	UID Name	UID ​Keyword	UID Type	Part
1.2.840.10008.​5.​1.​4.​1.​1.​66.​7	Label Map Segmentation Storage	Label​Map​Segmentation​Storage	SOP Class

Amend PS3.16 as follows (changes to existing text are bold and underlined for additions and struckthrough for removals):

Version: 2017091420240914

Segmentation Non-Image Source Purpose of Reference

Coding Scheme Designator	Code Value	Code Meaning	SNOMED-RT ID	UMLS Concept Unique ID
DCM	128227	Source real world value map
DCM	128228	Source segmentation

DICOM Controlled Terminology Definitions (Coding Scheme Designator "DCM" Coding Scheme Version "01")

Code Value	Code Meaning	Definition	Notes
128227	Source real world value map	Real world value map used as the source for derivation. E.g., the map applied to source images before processing them, such as for a threshold based segmentation operation.
128228	Source segmentation	Segmentation used as the source for derivation. E.g., the binary segmentation that was converted to a labelmap segmentation, or vice versa.