Материал: part03

Pixel Padding Value (0028,0120) and Pixel Padding Range Limit (0028,0121) are also used to identify pixels to be excluded from the​ normalgrayscalerenderingpipelineforotherreasons,suchassuppressionofbackgroundair.PixelPaddingRangeLimit(0028,0121)​ is defined in the Image Pixel Module.​

Note​

1.​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.​

2.​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 min-​ imum and maximum values of the pixels in the native image​

3.​No pixels in the native image will have a value equal to Pixel Padding Value.​

Pixel Padding Value (0028,0120) specifies either a single value of this padding value, or when combined with Pixel Padding Range​ Limit (0028,0121), a range of values (inclusive) that are padding.​

ThevaluesofPixelPaddingValue(0028,0120)andPixelPaddingRangeLimit(0028,0121)shallbevalidvalueswithintheconstraints​ defined by Bits Allocated (0028,0100), Bits Stored (0028,0101), and High Bit (0028,0102).​

The 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, 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).​

Note​

1.​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.​

2.​For projection radiography, when the relationship between pixel value and X-Ray Intensity is known (for example as​ definedbyPixelIntensityRelationship(0028,1040)andPixelIntensityRelationshipSign(0028,1041)),itisrecommended​ 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 neut-​ ralize 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 Display Shutter Module Section C.7.6.11.​

3.​The conditional requirement for the Pixel Padding Value Range Limit (0028,0121) in the Image Pixel Module means​ that it shall not be present unless Pixel Padding Value (0028,0120) is also present.​

4.​The range of values to be suppressed between Pixel Padding Value (0028,0120) and Pixel Padding Value Range Limit​ (0028,0121) is specified as being inclusive, that is the values themselves as well as all values between are suppressed.​

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5.​WhenPixelPaddingValueRangeLimit(0028,0121)ispresent,butnotsupportedbyarenderingapplication,theconstraint​ 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.​

Whenmodifyingequipmentchangesthepixelpaddingvalueintheimage,itshallchangethevaluesofPixelPaddingValue(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.​

Note​

1.​For example, if a CT image containing signed values from -1024 to 3191 and a Pixel Padding Value of -2000 and a​ Rescale Intercept of 0 is converted to an unsigned image with a Rescale Intercept 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.​

2.​If the modification involves lossy compression, which may result in changes to the pixel values, then the application of​ Pixel Padding Value and Pixel Padding Range Limit may result in a different appearance, and hence these Attributes​ may need different values also.​

C.7.5.1.1.3 Software Versions​

Software Versions (0018,1020) is a multi-valued Attribute. For equipment that is composed of several components, it may be used​ to identify the name and version for each of those components. This may also include the identifier and version of libraries or config-​ uration files that significantly affect the production of the SOP Instance.​

C.7.5.2 Enhanced General Equipment Module​

TableC.7-8bspecifiestheAttributesthatidentifyanddescribethepieceofequipmentthatproducedaSeriesofCompositeInstances.​

Note​

1.​This table contains a subset of the Attributes of General Equipment Module (Table C.7-8) but the Type Designation is​ changedintoType1.IncludingthisModuleinanIODoverwritestheTypeDesignationoftheGeneralEquipmentModule.​

2.​The Attributes are intended to be a primary identification of the system that produces the data (e.g., modality or work-​ station application providing the content of the SOP Instance) and not the identification of the component that encodes​ the SOP Instance (e.g., a commonly used DICOM encoding toolkit).​

Table C.7-8b. Enhanced General Equipment Module Attributes​

C.7.6 Common Image IE Modules​

The following Image IE Modules are common to all Composite Image IODs that reference the Image IE.​

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C.7.6.1 General Image Module​

Table C.7-9 specifies the Attributes that identify and describe an image within a particular Series.​

Table C.7-9. General Image Module Attributes​

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>Include Table C.7-11b “Image Pixel Macro Attributes”​ See Section C.7.6.1.1.6 for further explanation.​

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Enumerated Values:​

R​right​

L​left​

U​unpaired​

B​both left and right​

Shall be consistent with any laterality information contained in Primary​ Anatomic Structure Modifier Sequence (0008,2230) and/or Laterality​ (0020,0060), if present.​

Previous editions of this Standard specified use of the Referenced Waveform Sequence (0008,113A), but that use has been​ superseded by Referenced Instance Sequence (0008,114A). See PS3.3-2004.​

C.7.6.1.1 General Image Attribute Descriptions​

C.7.6.1.1.1 Patient Orientation​

Patient Orientation (0020,0020) relative to the image plane shall be specified by two values that designate the anatomical direction​ of the positive row axis (left to right) and the positive column axis (top to bottom). The first entry is the direction of the rows, given by​ the direction of the last pixel in the first row from the first pixel in that row. The second entry is the direction of the columns, given by​ the direction of the last pixel in the first column from the first pixel in that column. Shall be consistent with Image Orientation (Patient)​ (0020,0037), if both Attributes are present and Patient Orientation (0020,0020) is not zero length.​

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