Материал: part03

Output units = m*SV + b.​

Enumerated Values:​

0​

See Section C.8.11.3.1.2 for further explanation.​

Enumerated Values:​

1​

See Section C.8.11.3.1.2 for further explanation.​

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Required if View Code Sequence (0054,0220) is not present or is present​ with an Item value other than (119376003, SCT, "tissue specimen") or​ (127457009, SCT, "tissue specimen from breast"). May be present​ otherwise.​

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C.8.11.3.1 DX Image Attribute Descriptions​

C.8.11.3.1.1 Image Type​

Value 1 shall identify the Pixel Data Characteristics in accordance with Section C.7.6.1.1.2 where the Enumerated Values are defined​ to be ORIGINAL or DERIVED.​

Note​

DX images may still be of type ORIGINAL rather than DERIVED despite the possibility that they may have undergone some​ processing. In this case a DERIVED image would have undergone yet further processing to make it substantially different​ from the original.​

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Value 2 shall identify the Patient Examination Characteristics in accordance with Section C.7.6.1.1.2 where the Enumerated Values​ are defined to be PRIMARY or SECONDARY.​

Note​

DX images generally use PRIMARY value for images captured from patient exposure.​

If images from the same exposure exist with different Values of Image Type, then they shall have different SOP Instance UIDs.​

Note​

Source Image Sequence (0008,2112) may be used to relate these images.​

Value 3 (which is specific to the IOD) shall be present and have zero length (null value).​

Other Values (4 and beyond) are optional and implementation specific.​

C.8.11.3.1.2 Pixel Intensity Relationship and Grayscale Transformations​

Pixel Intensity Relationship (0028,1040) and Pixel Intensity Relationship Sign (0028,1041) describe how the stored pixel values in​ Pixel Data (7FE0,0010) are related to the X-Ray beam intensity incident on the detector.​

They do not define a transformation intended to be applied to the pixel data for presentation.​

Note​

For example, if Pixel Intensity Relationship (0028,1040) is LIN and Pixel Intensity Relationship Sign (0028,1041) is -1, then​ lower values of Pixel Data (7FE0,0010) indicate higher X-Ray beam intensities corresponding to less radiographically dense​ regions projected on the image such as through air, and higher values of Pixel Data (7FE0,0010) indicate lower X-Ray beam​ intensities corresponding to more radiographically dense regions projected on the image such as through bone and radio-​ opaque contrast agents.​

The transformation to be applied to the pixel data for presentation is defined by the successive application of the conceptual Modality​ LUT, the VOI Attributes and the conceptual Presentation LUT. This shall result in the output of P-Values.​

Rescale Slope (0028,1053) and Rescale Intercept (0028,1052) define a linear subset of a conceptual Modality LUT transformation.​ For IODs that include this Module, these Attributes define an identity transformation. IODs that include the DX Image Module shall​ not include the Modality LUT Module.​

The Presentation LUT Shape (2050,0020) defines a subset of a conceptual Presentation LUT. For IODs that include this Module, this​

Attributedefinesanidentitytransformationorinverseidentitytransformation.IODsthatincludetheDXImageModuleshallnotinclude​

the Presentation LUT Module.​

Photometric Interpretation (0028,0004) indicates whether lower values that are the output of the VOI Attributes should be displayed​ as darker or lighter. Since the output of the equivalent of a conceptual Presentation LUT is in P-Values, which are defined in PS3.14​ suchthatlowervaluescorrespondtolowerluminancelevels,thenthedefinitionofthePresentationLUTShape(2050,0020),otherwise​ intended to be an identity transformation, must take into account the effect of the value specified for Photometric Interpretation​ (0028,0004).​

Note​

Regardless of the values of Pixel Intensity Relationship (0028,1040) and Pixel Intensity Relationship Sign (0028,1041), the​ grayscaletransformationstobeappliedtoPixelData(7FE0,0010)aredefinedbytheequivalentoftheModalityLUT(Rescale​ Slope (0028,1053) and Rescale Intercept (0028,1052)), Value of Interest Attributes, Photometric Interpretation (0028,0004)​ andtheequivalentofthePresentationLUT(PresentationLUTShape(2050,0020)).However,thecombinationofthegrayscale​ transformations and the description of the pixel intensity relationship, together define whether, for example, air is expected​ to be displayed as black or white.​

C.8.11.3.1.3 Acquisition Device Processing Description​

Acquisition Device Processing Description (0018,1400) provides some indication in human readable text of the digital processing on​ theimagesbeforeexchange.Examplesofthisprocessingare:edgeenhanced,subtracted,timefiltered,gammacorrected,convolved​ (spatially filtered).​

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C.8.11.3.1.4 Derivation Description​

If an Image is identified to be a Derived image in Image Type (0008,0008), Derivation Description (0008,2111) is an optional and​ implementation specific text description of the way the image was derived from an original image. As applied to DX images, it may​ be used to describe derivation operations such as edge enhancement, temporal filtering, digital subtraction, or other linear and non-​ linear transformations.​

C.8.11.3.1.5 VOI Attributes​

The Attributes of the VOI LUT Module are specialized in the DX Image Module.​

Window Center (0028,1050) and Window Width (0028,1051) specify a linear conversion (unless otherwise specified by the value of​ VOI LUT Function (0028,1056); See Section C.11.2.1.3) from the output of the (conceptual) Modality LUT values to the input to the​ (conceptual) Presentation LUT. Window Center contains the value that is the center of the window. Window Width contains the width​ of the window.​

The application of Window Center (0028,1050) and Window Width (0028,1051) shall not produce a signed result.​

Note​

IfthePresentationLUTShape(2050,0020)isIDENTITY,thentheresultofapplyingWindowCenter(0028,1050)andWindow​ Width (0028,1051) is P-Values.​

If multiple values are present, both Attributes shall have the same number of values and shall be considered as pairs. Multiple values​ indicate that multiple alternative views should be presented.​

The VOI LUT Sequence specifies a (potentially non-linear) conversion from the output of the (conceptual) Modality LUT values to the​ input to the (conceptual) Presentation LUT.​

If multiple Items are present in VOI LUT Sequence (0028,3010), only one shall be applied. Multiple Items indicate that multiple altern-​ ative views should be presented.​

If any VOI LUT Attributes are included by an Image, a Window Width and Window Center or the VOI LUT Table, but not both, shall​ be applied to the Image for display. Inclusion of both indicates that multiple alternative views should be presented.​

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

The first value is the number of entries in the lookup table.​

The second value is the first stored pixel value mapped. This pixel value is mapped to the first entry in the LUT. All image pixel values​ less than the first value mapped are also mapped to the first entry in the LUT Data. An image pixel value one greater than the first​ value mapped is mapped to the second entry in the LUT Data. Subsequent image pixel values are mapped to the subsequent entries​ in the LUT Data up to an image pixel value equal to number of entries + first value mapped - 1 that is mapped to the last entry in the​ LUT Data. Image pixel values greater than 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 (analogous to "bits stored"). It shall be between 10-16.​ The LUT Data shall be stored in a format equivalent to 16 "bits allocated" and "high bit" equal to "bits stored" - 1. The third value​ conveys the range of LUT entry values. These unsigned LUT entry values shall range between 0 and 2n-1, where n is the third value​ of the LUT Descriptor.​

Note​

1.​The third value is restricted in the VOI LUT Module to 8 or 16 but is specialized here.​

2.​The first and second values are not specialized and are the same as in the VOI LUT Module.​

LUT Data (0028,3006) contains the LUT entry values.​

C.8.11.4 DX Detector Module​

Table C.8-71 contains IOD Attributes that describe a DX detector.​

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