Материал: part03

C.7.6.16.2.9b Identity Pixel Value Transformation Macro​

Table C.7.6.16-10b specifies the Attributes of the Identity Pixel Value Transformation Functional Group Macro.​

Note​

This Macro constrains the Modality LUT Transformation step in the grayscale rendering pipeline to be an identity transform-​ ation.​

Table C.7.6.16-10b. Identity Pixel Value Transformation Macro Attributes​

Intercept (0028,1052).​

See Section C.11.1.1.2 for further explanation.​

Enumerated Values:​

US​Unspecified​

C.7.6.16.2.10 Frame VOI LUT Macro​

Table C.7.6.16-11 specifies the Attributes of the Frame VOI LUT Functional Group Macro.​

Table C.7.6.16-11. Frame VOI LUT Macro Attributes​

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See Section C.11.2.1.3 for further explanation.​

Defined Terms:​

LINEAR​

LINEAR_EXACT​

SIGMOID​

When this Attribute is not present, the interpretation of the values of​ Window Center (0028,1050) and Window Width (0028,1051) is linear​ as in Section C.11.2.1.2.​

C.7.6.16.2.10b Frame VOI LUT With LUT Macro​

Table C.7.6.16-11b specifies the Attributes of the Frame VOI LUT With LUT Functional Group Macro. This Macro contains one or​ more sets of linear or sigmoid window values and/or one or more sets of lookup tables.​

Table C.7.6.16-11b. Frame VOI LUT with LUT Macro Attributes​

OnlyasingleItemispermittedinthisSequence.​

>Include Table C.11-2b “VOI LUT Macro Attributes”​

C.7.6.16.2.11 Real World Value Mapping Macro​

Table C.7.6.16-12 specifies the Attributes of the Real World Value Mapping Functional Group Macro.​

Table C.7.6.16-12. Real World Value Mapping Macro Attributes​

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DICOM PS3.3 2020a - Information Object Definitions​ Page 573​

Table C.7.6.16-12b. Real World Value Mapping Item Macro Attributes​

Required if Real World Value Last Value Mapped (0040,9211) is absent.​

Note​

The same Attribute with a double float precision value is used​ whether or not Float Pixel Data (7FE0,0008) or Double Float Pixel​ Data (7FE0,0009) are present, an integer value is not sufficient.​

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See Section C.7.6.16.2.11.1 for further explanation.​

>Include Table 8.8-1 “Code Sequence Macro Attributes”​DCID 7181 “Abstract Multi-dimensional Image Model Component Units”, or​

One or more Items are permitted in this Sequence.​

>Include Table 10.2.1-1 “Content Item with Modifiers​ Baseline TID is TID 15400 “Real-World Quantity Definition”.​

Macro Attributes”​

Other TIDs may be defined by the IOD or application that uses this Macro.​

C.7.6.16.2.11.1 Real World Value Representation​

C.7.6.16.2.11.1.1 Real World Value Mapping Sequence​

The Items in the Real World Value Mapping Sequence (0040,9096) may be used to translate stored values into real world values​ when there is such a relationship. The Real World Value Mapping Sequence (0040,9096) is independent of the Modality LUT (or​ Pixel Value Transformation Macro), as illustrated in Figure C.7.6.16-6.​

Each Item specifies the range of stored values as well as the associated mapping function. Each Item can specify either a linear​ mapping, using Real World Value Slope (0040,9225) and Real World Value Intercept (0040,9224), or a non-linear mapping using​ Real World Value LUT Data (0040,9212). More than one Real World Value Mapping Item is allowed.​

TherangeofstoredpixelvaluesspecifiedbydifferentRealValueWorldMappingSequence(0040,9096)Itemscanoverlap(asillustrated​ in the example in Figure C.7.6.16-7).​

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Stored

Values

Figure C.7.6.16-6. The Real World Value LUT and the Image Viewing Pipeline​

Note​

For example, MR images may contain data that is not only the result of the physical/chemical properties of the scanned​ anatomy, but may also contain information that is representing real world values, such as, temperature [in degrees C], flow​ [in l/min], speed [in m/sec], relative activity [in %], relative contrast enhancement [in %], diffusion [in sec/mm2], etc.​

In some cases the conversion from Stored Values to Real World Values can be linear (through "slope" and "intercept") or non-linear​ (through look-up tables).​

Both transformation methods can be applied to one range of stored values. Overlapped ranges might be used for different represent-​ ations such as log versus linear scales or for different representations in units such as cm/sec versus mm/sec. Alternative methods​ can be identified by the labels assigned to the transformations.​

C.7.6.16.2.11.1.2 Real World Values Mapping Sequence Attributes​

The Real World Value First Value Mapped (0040,9216) and Real World Value Last Value Mapped (0040,9211) Attributes describe​ the range of stored pixel values that are mapped by the Sequence Item. Stored pixel values less than the first value mapped, or​ greater than the last value mapped have no real value attached.​

When the Real World Value Intercept (0040,9224) and Real World Value Slope (0040,9225) Attributes are supplied, the stored value​ (SV) is converted to a real world value (RV) using the equation:​

RV = (Real World Value Slope) * SV + Real World Value Intercept​

When the Real World Value LUT Data (0040,9212) Attribute is supplied, Real World Values are obtained via a lookup operation. The​ stored pixel value of the first value mapped is mapped to the first 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 the last value mapped.​

The number of entries in the LUT data is given by:​

Number of entries = Real World Value Last Value MappedReal World Value First Value Mapped + 1​

Note​

If the stored pixel values that are encoded as floating point rather than integer values, only the equation and not the lookup​ operation is defined.​

TheValueRepresentationofRealWorldValueFirstValueMapped(0040,9216)andRealWorldValueLastValueMapped(0040,9211)​ (US or SS) is determined by the value of Pixel Representation (0028,0103) in the case of integer pixel data, or is SS in the case of​ floating point pixel data if these Attributes are present.​

Note​

In practice, integer values may well be sufficient to define an input range that exceeds the actual stored floating point pixel​ value range. The reason to permit floating point alternatives to an integer range is that sometimnes the stored floating point​ values may be very large and exceed what can be specified as an integer value.​

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