Pixel Spacing Attribute
| Tag | (0028,0030) |
|---|---|
| Type | Conditionally Required (1C) |
| Keyword | PixelSpacing |
| Value Multiplicity | 2 |
| Value Representation | Decimal String (DS) |
| Example Values |
|
Physical distance in the imaging target (patient, specimen, or phantom) between the centers of each pixel, specified by a numeric pair - adjacent row spacing (delimiter) adjacent column spacing in mm. See Section 10.7.1.3 for further explanation of the value order.
Note
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In the case of CT images with an Acquisition Type (0018,9302) of CONSTANT_ANGLE, the pixel spacing is that in a plane normal to the central ray of the diverging X-Ray beam as it passes through the data collection center.
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In the case of Enhanced RT Image ("1.2.840.10008.5.1.4.1.1.481.23") or Enhanced Continuous RT Image ("1.2.840.10008.5.1.4.1.1.481.24") the pixel spacing is defined on the x/y plane at z = 0 of the Image Receptor Coordinate System.
Required if:
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Volumetric Properties (0008,9206) is other than DISTORTED or SAMPLED, and Image Type (0008,0008) Value 3 is not LABEL or OVERVIEW, or
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SOP Class UID is Segmentation Storage ("1.2.840.10008.5.1.4.1.1.66.4") and Frame of Reference UID (0020,0052) is present, or
-
SOP Class UID is Ophthalmic Tomography Image Storage ("1.2.840.10008.5.1.4.1.1.77.1.5.4") and Ophthalmic Volumetric Properties Flag (0022,1622) is YES, or
-
SOP Class UID is Ophthalmic Optical Coherence Tomography B-scan Volume Analysis Storage ("1.2.840.10008.5.1.4.1.1.77.1.5.8"), or
-
SOP Class UID is Enhanced RT Image ("1.2.840.10008.5.1.4.1.1.481.23"), or
-
SOP Class UID is Enhanced Continuous RT Image ("1.2.840.10008.5.1.4.1.1.481.24").
May be present otherwise.
Note
Part of the Pixel Measures Functional Group Macro with usage: C
Required if Derivation Image Functional Group (C.7.6.16.2.6) is not present and the Frame of Reference is defined in the patient-relative Reference Coordinate System. May be present otherwise if the Frame of Reference is defined in the patient-relative Reference Coordinate System. See Section A.51.5.1.
Section 10.7.1.3
10.7.1.3 Pixel Spacing Value Order and Valid Values
All pixel spacing related Attributes are encoded as the physical distance between the centers of each two-dimensional pixel, specified by two numeric values.
The first value is the row spacing in mm, that is the spacing between the centers of adjacent rows, or vertical spacing.
The second value is the column spacing in mm, that is the spacing between the centers of adjacent columns, or horizontal spacing.
To illustrate, consider the example shown in Figure 10.7.1.3-1.
Figure 10.7.1.3-1. Example of Pixel Spacing Value Order
Pixel Spacing = Row Spacing \ Column Spacing = 0.30\0.25.
All pixel spacing related Attributes shall have positive non-zero values, except when there is only a single row or column or pixel of data present, in which case the corresponding value may be zero.
Note
A single row or column or "pixel" may occur in MR Spectroscopy Instances.
This description applies to:
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Pixel Spacing (0028,0030)
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Imager Pixel Spacing (0018,1164)
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Nominal Scanned Pixel Spacing (0018,2010)
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Image Plane Pixel Spacing (3002,0011)
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Compensator Pixel Spacing (300A,00E9)
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Detector Element Spacing (0018,7022)
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Presentation Pixel Spacing (0070,0101)
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Printer Pixel Spacing (2010,0376)
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Object Pixel Spacing in Center of Beam (0018,9404)