Материал: part03

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C.10.10.1 Waveform Annotation Attribute Descriptions​

C.10.10.1.1 Referenced Channels​

Referenced Waveform Channels (0040,A0B0) is a multi-value Attribute that lists the channels to which an annotation of a waveform​ applies. Each channel is specified as a pair of values (M,C), where the first value is the ordinal of the Item of Waveform Sequence​ (5400,0100) (i.e., the Multiplex Group Number), and the second value is the ordinal of the Item of the Channel Definition Sequence​ (003A,0200) Attribute (i.e., the Waveform Channel Number) within the multiplex group.​

If the specified channel number is 0, the annotation applies to all channels in the multiplex group.​

Note​

As an example, an annotation that applies to the entire first multiplex group and channels 2 and 3 of the third multiplex group​ would have Referenced Channels value 0001 0000 0003 0002 0003 0003.​

C.10.10.1.2 Temporal Range Type​

The Temporal Range Type (0040,A130) Attribute defines the type of temporal extent of the annotated region of interest. A temporal​ point (or instant of time) may be defined by a waveform sample offset (for a single waveform multiplex group only), time offset, or​ absolute time.​

Enumerated Values:​

C.10.10.1.3 Referenced Sample Positions​

Referenced Sample Positions (0040,A132) may be used only if Referenced Waveform Channels (0040,A0B0) refers to channels​ within a single multiplex group. The sample position is by channel, and applies to all channels specified in Referenced Channels​ (0040,A0B0).​

C.10.10.1.4 Annotation Group Number​

The Annotation Group Number (0040,A180) allows the logical association of multiple annotations within the current SOP Instance.​ Such linked annotations share an Annotation Group Number, but each annotation is semantically separable. The nature of the asso-​ ciation is not defined. The number is not semantically significant.​

Note​

For instance, the R-wave in several waveform channels may be annotated, and all occurrences of the same R-wave could​ be linked in an annotation group.​

C.10.11 Graphic Group Module​

Graphic Group Module provides the label and description for the logical associations made by the Graphic Group ID (0070,0295) of​ graphic objects.​

The grouping concept used in the Graphic Group Module differs from the grouping concept used in the Graphic Layer Module.​ GraphicLayerModuleaddressestherenderingorderbyusingtheGraphicLayerOrder(0070,0062),whichspecifieswhichannotations​ arerenderedfirst.TheGraphicGroupModuleisusedtospecifywhichannotationsbelongtogetherandshallbehandledtogether(e.g.,​ rotate, move) independent of the Graphic Layer to which they are assigned.​

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DICOM PS3.3 2020a - Information Object Definitions​ Page 1293​

Table C.10-12. Graphic Group Module Attributes​

C.11 Look Up Tables and Presentation States​

C.11.1 Modality LUT Module​

Table C.11-1 specifies the Attributes that describe the Modality LUT.​

Either a Modality LUT Sequence containing a single Item or Rescale Slope and Intercept values shall be present but not both.​

Note​

This requirement for only a single transformation makes it possible to unambiguously define the input of succeeding stages​ of the grayscale pipeline such as the VOI LUT.​

Table C.11-1. Modality LUT Module Attributes​

Attribute Name​ Tag​ Type​ Attribute Description​

Include Table C.11-1b “Modality LUT Macro Attributes”​

Table C.11-1b. Modality LUT Macro Attributes​

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Intercept (0028,1052).​

See Section C.11.1.1.2 for further explanation.​

Required if Rescale Intercept is present.​

C.11.1.1 LUT Attribute Descriptions​

C.11.1.1.1 LUT Descriptor​

The three values of LUT Descriptor (0028,3002) describe the format of the LUT Data in the corresponding LUT Data (0028,3006)​ Attribute.​

The first value is the number of entries in the lookup table. When the number of table entries is equal to 216 then this value shall be​ 0.​

The second value is the first stored pixel value mapped. The Value Representation of the second value (US or SS) is specified by​ Pixel Representation (0028,0103). This stored pixel value is mapped to the first entry in the LUT. All stored pixel values less than the​ first value mapped are also mapped to the first entry in the LUT Data. A stored pixel value one greater than the first value mapped is​ mapped to the second entry in the LUT Data. Subsequent stored pixel values are mapped to the subsequent entries in the LUT Data​ up to a stored pixel value equal to number of entries + first value mapped - 1 that is mapped to the last entry in the LUT Data. Stored​ pixel values greater than or equal to number of entries + first value mapped are also mapped to the last entry in the LUT Data.​

The third value specifies the number of bits for each entry in the LUT Data. It shall take the value 8 or 16. The LUT Data shall be​ stored in a format equivalent to 8 bits allocated when the number of bits for each entry is 8, and 16 bits allocated when the number​ of bits for each entry is 16, where in both cases the high bit is equal to bits allocated - 1.​

Note​

Some implementations have encoded 8 bit entries with 16 bits allocated, padding the high bits; this can be detected by​ comparing the number of entries specified in the LUT Descriptor with the actual value length of the LUT Data entry. The​ value length in bytes should equal the number of entries if bits allocated is 8, and be twice as long if bits allocated is 16.​

The third value also conveys the range of LUT entry values. It shall take the value 8 or 16, corresponding with the LUT entry value​ range of 256 or 65536.​

Note​

Since LUT Descriptor (0028,3002) is 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 Represent-​ ation (0028,0103).​

The LUT Data contains the LUT entry values.​

TheoutputrangeoftheModalityLUTModuledependsonwhetherornotRescaleSlope(0028,1053)andRescaleIntercept(0028,1052)​ or the Modality LUT Sequence (0028,3000) are used.​

In the case where Rescale Slope and Rescale Intercept are used, the output ranges from (minimum pixel value*Rescale​ Slope+RescaleIntercept)to(maximumpixelvalue*RescaleSlope+RescaleIntercept),wheretheminimumandmaximumpixelvalues​ are determined by Bits Stored and Pixel Representation.​

Note​

This range may be signed even if Pixel Representation is unsigned.​

In the case where the Modality LUT Sequence is used, the output range is from 0 to 2n-1 where n is the third value of LUT Descriptor.​ This range is always unsigned.​

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C.11.1.1.2 Modality LUT and Rescale Type​

Specifies the units of the output of the Modality LUT or rescale operation.​

Defined Terms:​

OD​ The number in the LUT represents thousands of optical density. That is, a value of 2140 represents an optical density of​ 2.140.​

HU​ Hounsfield Units (CT)​ US​ Unspecified​ MGML​ mg/ml​

Z_EFF​ Effective Atomic Number (i.e., Effective-Z)​ ED​ Electron density in 1023 electrons/ml​

EDW​ Electron density normalized to water in units of N/Nw where N is number of electrons per unit volume, and Nw is number​ of electrons in the same unit of water at standard temperature and pressure.​

HU_MOD​Modified Hounsfield Unit​ PCT​ Percentage (%)​

Other values are permitted, but are not defined by the DICOM Standard.​

C.11.1.1.2.1 Recommended Rescale Type Assignments For Multi-energy CT Image​

Multi-energy CT Images can have multiple assignments of Rescale Types to Image Type Attributes. These are the recommended​ assignments for Rescale Type and Real World Value Mapping Attributes.​

Table C.11.1.1.2.1-1. Recommended Rescale Type Assignments for Multi-energy CT Image​

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