C.8.20 Segmentation

This section describes the specific modules for the Segmentation IOD.

C.8.20.1 Segmentation Series Module

Table C.8.20-1 defines the general Attributes of the Segmentation Series Module.

Table C.8.20-1SEGMENTATION SERIES MODULE ATTRIBUTES

Attribute Name Tag Type Attribute Description
Modality (0008,0060) 1 Modality Type Enumerated Value: 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 (e.g. a Modality or General-Purpose Performed Procedure Step SOP). Only a single Item shall be included in this sequence. Required if the SOP Instance was created in a workflow managed with the Modality Performed Procedure Step SOP Class or General Purpose Performed Procedure Step SOP Class.
>Include ‘SOP Instance Reference Macro' Table 10-11

C.8.20.2 Segmentation Image Module

Table C.8.20-2 defines the general Attributes of the Segmentation Image Module.

Table C.8.20-2SEGMENTATION IMAGE MODULE ATTRIBUTES

Attribute Name Tag Type Attribute Description
Image Type (0008,0008) 1 Value 1 shall be DERIVED. Value 2 shall be PRIMARY. No other values shall be present.
Include Content Identification Macro Table 10-12
Samples Per Pixel (0028,0002) 1 Enumerated Values: 1
Photometric Interpretation (0028,0004) 1 Enumerated Values: MONOCHROME2
Pixel Representation (0028,0103) 1 Enumerated Values: 0
Bits Allocated (0028,0100) 1 If Segmentation Type (0062,0001) is BINARY, shall be 1. Otherwise it shall be 8. See Section C.8.20.2.1.
Bits Stored (0028,0101) 1 If Segmentation Type (0062,0001) is BINARY, shall be 1. Otherwise it shall be 8. See Section C.8.20.2.1.
High Bit (0028,0102) 1 If Segmentation Type (0062,0001) is BINARY, shall be 0. Otherwise it shall be 7. See Section C.8.20.2.1.
Lossy Image Compression (0028,2110) 1 Specifies whether an Image has undergone lossy compression. Enumerated Values: 00 = Image has NOT been subjected to lossy compression. 01 = Image has been subjected to lossy compression. See Section C.8.20.2.2
Lossy Image Compression Ratio (0028,2112) 1C Describes the approximate lossy compression ratio(s) that have been applied to this image. See C.7.6.1.1.5 for further explanation. May be multivalued if successive lossy compression steps have been applied. Notes: 1. For example, a compression ratio of 30:1 would be described in this Attribute with a single value of 30. 2. For historical reasons, the lossy compression ratio may also be described in Derivation Description (0008,2111). 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 C.7.6.1.1.5 for further explanation. May be multivalued if successive lossy compression steps have been applied; the value order shall correspond to the values of Lossy Image Compression Ratio (0028,2112). Note: For historical reasons, the lossy compression method may also be described in Derivation Description (0008,2111). Required if present in the source images or this IOD instance has been compressed. See section C.8.20.2.2.
Segmentation Type (0062,0001) 1 The type of encoding used to indicate the presence of the segmented property at a pixel/voxel location. Enumerated Values are: BINARY FRACTIONAL See section C.8.20.2.3.
Segmentation Fractional Type (0062,0010) 1C For fractional segmentation encoding, the meaning of the fractional value. Enumerated Values are: PROBABILITY OCCUPANCY Required if Segmentation Type (0062,0001) is FRACTIONAL. See section C.8.20.2.3.
Maximum Fractional Value (0062,000E) 1C Specifies the value that represents 100%. There shall be no values in Pixel Data (7FE0,0010) greater than this value. Required if Segmentation Type (0062,0001) is FRACTIONAL.
Segment Sequence (0062,0002) 1 Describes the segments that are contained within the data. One or more Items shall be included in this sequence.
>Segment Number (0062,0004) 1 Identification number of the segment. The value of Segment Number (0062,0004) shall be unique within the Segmentation instance in which it is created. See C.8.20.2.4.
>Segment Label (0062,0005) 1 User-defined label identifying this segment. This may be the same as the Code Meaning (0008,0104) of the Segmented Property Type Code Sequence (0062,000F).
>Segment Description (0062,0006) 3 User-defined description for this segment.
>Segment Algorithm Type (0062,0008) 1 Type of algorithm used to generate the segment. Enumerated Values are: AUTOMATIC: calculated segment SEMIAUTOMATIC: calculated segment with user assistance MANUAL: user-entered segment
>Segment Algorithm Name (0062,0009) 1C Name of algorithm used to generate the segment. Required if Segment Algorithm Type (0062,0008) is not MANUAL.
>Segment Surface Generation Algorithm Identification Sequence (0066,002D) 3 A description of how this segment was derived. Only a single item is permitted in this sequence.
>>Include ‘Algorithm Identification Macro’ Table 10-19 Baseline Context ID is 7162 Surface Processing Algorithm Families.
>Include ‘General Anatomy Mandatory Macro’ Table 10-5
>Segmented Property Category Code Sequence (0062,0003) 1 Sequence defining the general category of this segment. Only a single item shall be included in this sequence.
>>Include ‘Code Sequence Macro’ Table 8.8-1 Baseline CID 7150.
>Segmented Property Type Code Sequence (0062,000F) 1 Sequence defining the specific property type of this segment. Only a single item shall be included in this sequence.
>>Include ‘Code Sequence Macro’ Table 8.8-1 Baseline CID 7151.
>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 segment 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). Note: 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 segment be rendered on a color display. The units are specified in PCS-Values, and the value is encoded as CIELab. See C.10.7.1.1.

C.8.20.2.1 Bits Allocated and Bits Stored

As a consequence of the enumerated Bits Allocated and Bits Stored attribute values, single bit pixels shall be packed 8 to a byte as defined by the encoding rules in PS 3.5.

C.8.20.2.2 Lossy Image Compression and Lossy Image Compression Method

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”.

Notes: It is not advisable to lossy compress a Segmentation SOP Instance. In particular, a binary segmentation should not be lossy compressed.

C.8.20.2.3 Segmentation Type and Segmentation Fractional Type

BINARY indicates the segmented property is present with a value of 1 and absent with a value of 0.

FRACTIONAL segmentation is defined as a value from zero to the Maximum Fractional Value (0062,000E). A FRACTIONAL segmentation shall be further specified via the Segmentation Fractional Type (0062,0010) attribute, with the following values:

PROBABILITY Defines the probability, as a percentage, that the segmented property occupies the spatial area defined by the voxel.

OCCUPANCY Defines the percentage of the voxel area occupied by the segmented property.

C.8.20.2.4 Segment Number

Segment Number (0062,0004) shall be unique within each instance, start at a value of 1, and increase monotonically by 1.

C.8.20.3 Segmentation Functional Group Macros

The following sections contain Functional Group macros specific to the Segmentation IOD.

Note: 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”.

C.8.20.3.1 Segmentation Macro

Table C.8.20-3 specifies the attributes of the Segmentation Functional Group macro.

Table C.8.20-3SEGMENTATION 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 segment described in the Segment Sequence (0062,0002) by reference to the Segment Number (0062,0004). Referenced Segment Number (0062,000B) shall not be multi-valued.