CP-1526 Correct order of reference to pixel spacing values in SR Image Library Status Final Text Date of Last Update 2016/03/14 Person Assigned David Clunie Submitter Name Jörg Riesmeier Submission Date 2015/08/21 Correction Number CP-1526 Log Summary: Correct order of reference to pixel spacing values in SR Image Library Name of Standard PS3.16 2016a Rationale for Correction: Sup 50 (Mammo CAD) introduced the concept of an Image Library, which contains descriptions of relevant Attributes of images extracted from the images. This included pixel spacing information, which in images is contained in a single multi-valued Attribute, whereas in SR, spacing is split into separate horizontal and vertical content items. The concept of an Image Library has been reused in other CAD and measurement applications, and the same concepts used in other templates. In specifying the source of which value was horizontal and which vertical when copying into the separate concepts, the order was specified opposite that of the PS3.3 definition. CP 626 was intended to clarify once and for all the (not terribly clear) PS3.3 Attribute description, which is "specified by a numeric pair - adjacent row spacing (delimiter) adjacent column spacing", but only addressed the description in PS3.3. CP 626 uses the same words as the names of the SR concepts ("horizontal spacing" and "vertical spacing"). In practice, pixels are almost always square, so no issue is encountered in the installed base when using the values (e.g., for measurements), but the order in PS3.16 should be corrected. Correction Wording: <section> <title/> <informaltable rules="all" frame="box"> <tr> <td><para><emphasis role="italic">Amend PS 3.16 to correct order of reference to spacing values</emphasis></para></td> </tr> </informaltable> </section> <section label="TID 1603" status="3" xml:id="sect_TID_1603"> <title>Image Library Entry Descriptors for Projection Radiography ...
Image Library Entry Descriptors for Projection Radiography
NL Rel with Parent VT Concept Name VM Req Type Condition Value Set Constraint
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5 HAS ACQ CONTEXT NUM EV (111026, DCM, "Horizontal Pixel Spacing") 1 U UNITS = EV (mm, UCUM, "millimeter")
6 HAS ACQ CONTEXT NUM EV (111066, DCM, "Vertical Pixel Spacing") 1 U UNITS = EV (mm, UCUM, "millimeter")
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Content Item Descriptions ... ... Horizontal Imager Pixel Spacing The row (first) second component of Imager Pixel Spacing (0018,1164) in the Image IOD. See . Vertical Imager Pixel Spacing The column (second) first component of Imager Pixel Spacing (0018,1164) in the Image IOD. See .
Image Library Entry Descriptors for Cross-Sectional Modalities ...
Image Library Entry Descriptors for Cross-Sectional Modalities
NL Rel with Parent VT Concept Name VM Req Type Condition Value Set Constraint
1 HAS ACQ CONTEXT NUM EV (111026, DCM, "Horizontal Pixel Spacing") 1 U UNITS = EV (mm, UCUM, "millimeter")
2 HAS ACQ CONTEXT NUM EV (111066, DCM, "Vertical Pixel Spacing") 1 U UNITS = EV (mm, UCUM, "millimeter")
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Content Item Descriptions Horizontal Imager Pixel Spacing The row (first) second component of Pixel Spacing (0028,0030) in the Image IOD. See and . Vertical Imager Pixel Spacing The column (second) first component of Pixel Spacing (0028,0030) in the Image IOD. See and .
Calibration ...
Calibration
NL Rel with Parent VT Concept Name VM Req Type Condition Value Set Constraint
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9 > CONTAINS INCLUDE DTID 300 "Measurement" 1 M $Measurement = EV (111026, DCM, "Horizontal Pixel Spacing") $Unit = DT (mm/{pixel}, UCUM, "mm/pixel") $ImagePurpose = EV (121112, DCM, "Source of Measurement")
10 > CONTAINS INCLUDE DTID 300 "Measurement" 1 M $Measurement = EV (111066, DCM, "Vertical Pixel Spacing") $Unit = DT (mm/{pixel}, UCUM, "mm/pixel") $ImagePurpose = EV (121112, DCM, "Source of Measurement")
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Content Item Descriptions ... ... Row 9, 10 Spacing in the patient body. Point to a single frame containing the image used for calibration if applicable, the actual measurements may be indicated by a SCOORD (see TID 320 "Image or Spatial Coordinates", row 3) ... ...
CAD Image Library Entry ...
CAD Image Library Entry
NL Rel with Parent VT Concept Name VM Req Type Condition Value Set Constraint
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11 > HAS ACQ CONTEXT NUM EV (111026, DCM, "Horizontal Pixel Spacing") 1 MC Shall be present if (0018,1164) or (0028,0030) is in the Image Instance UNITS = EV (um, UCUM, "micrometer") UNITS = EV (mm, UCUM, "millimeter")
12 > HAS ACQ CONTEXT NUM EV (111066, DCM, "Vertical Pixel Spacing") 1 MC Shall be present if (0018,1164) or (0028,0030) is in the Image Instance UNITS = EV (um, UCUM, "micrometer") UNITS = EV (mm, UCUM, "millimeter")
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Content Item Descriptions ... ... Horizontal Imager Pixel Spacing The row (first) second component of Imager Pixel Spacing (0018,1164) in the Image IOD. See . Vertical Imager Pixel Spacing The column (second) first component of Imager Pixel Spacing (0018,1164) in the Image IOD. See .
CAD Common Image Properties Entry ...
CAD Common Image Properties Entry
NL Rel with Parent VT Concept Name VM Req Type Condition Value Set Constraint
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7 > CONTAINS NUM EV (111026, DCM, "Horizontal Pixel Spacing") 1 M Shall be taken from value 12 of Pixel Spacing (0028,0030) in the Image Instances. UNITS = EV (mm/{pixel}, UCUM, "millimeters per pixel")
8 > CONTAINS NUM EV (111066, DCM, "Vertical Pixel Spacing") 1 M Shall be taken from value 21 of Pixel Spacing (0028,0030) in the Image Instances. UNITS = EV (mm/{pixel}, UCUM, "millimeters per pixel")
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Implantation Plan ...
Implantation Plan
NL Rel with Parent VT Concept Name VM Req Type Condition Value Set Constraint
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31 >>> HAS PROPERTIES NUM EV (111026, DCM, "Horizontal Pixel Spacing") 1 M UNITS = EV (mm/{pixel}, UCUM, "mm/pixel")
32 >>> HAS PROPERTIES NUM EV (111026111066, DCM, "Vertical Pixel Spacing") 1 M UNITS = EV (mm/{pixel}, UCUM, "mm/pixel")
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Content Item Descriptions ... ... Row 31 Defines the calibrated Horizontal Pixel Spacing that was used by the planning application, which may be different from the spacing encoded in the referenced Image SOP Instance. Row 32 Defines the calibrated Vertical Pixel Spacing that was used by the planning application, which may be different from the spacing encoded in the referenced Image SOP Instance. ... ...
<informaltable rules="all" frame="box"> <tr> <td><para><emphasis role="italic">For reference DICOM PS 3.3 pixel spacing description:</emphasis></para></td> </tr> </informaltable> </section> <section label="10.7" status="2" xml:id="sect_10.7"> <title>Basic Pixel Spacing Calibration Macro defines the Attributes for the Basic Pixel Spacing Calibration Macro.
Basic Pixel Spacing Calibration Macro Attributes
Attribute Name Tag Type Attribute Description
Pixel Spacing (0028,0030) 1C Physical distance in the patient between the center of each pixel, specified by a numeric pair - adjacent row spacing (delimiter) adjacent column spacing in mm. See and . Required if the image has been calibrated. May be present otherwise.
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Basic Pixel Spacing Calibration Macro Attribute Descriptions
Pixel Spacing Pixel Spacing (0028,0030) specifies the physical distance in the patient between the center of each pixel. ...
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 .
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. A single row or column or "pixel" may occur in MR Spectroscopy instances. This description applies to: Pixel Spacing (0028,0030) Imager Pixel Spacing (0018,1164) Nominal Scanned Pixel Spacing (0018,2010) Image Plane Pixel Spacing (3002,0011) Compensator Pixel Spacing (300A,00E9) Detector Element Spacing (0018,7022) Presentation Pixel Spacing (0070,0101) Printer Pixel Spacing (2010,0376) Object Pixel Spacing in Center of Beam (0018,9404)
Image Plane Module ...
Image Plane Module Attributes
Attribute Name Tag Type Attribute Description
Pixel Spacing (0028,0030) 1 Physical distance in the patient between the center of each pixel, specified by a numeric pair - adjacent row spacing (delimiter) adjacent column spacing in mm. See for further explanation.
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DX Detector Module contains IOD Attributes that describe a DX detector.
DX Detector Module Attributes
Attribute Name Tag Type Attribute Description
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Imager Pixel Spacing (0018,1164) 1 Physical distance measured at the front plane of the detector housing between the center of each image pixel specified by a numeric pair - row spacing value(delimiter) column spacing value in mm. See for further explanation of the value order. The value of this attribute shall never be adjusted to account for correction for the effect of geometric magnification or calibration against an object of known size; Pixel Spacing (0028,0030) is specified for that purpose.
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<informaltable rules="all" frame="box"> <tr> <td><para><emphasis role="italic">For reference DICOM PS3.16 concept definitions:</emphasis></para></td> </tr> </informaltable> </section> <section> <title/> <table frame="box" label="D-1" rules="all" xml:id="table_D-1"> <caption>DICOM Controlled Terminology Definitions</caption> <thead> <tr valign="top"> <th align="center" colspan="1" rowspan="1"> <para xml:id="para_f05607a1-90fe-4408-ad56-d194c3203ae5"> <emphasis role="bold">Code Value</emphasis> </para> </th> <th align="center" colspan="1" rowspan="1"> <para xml:id="para_022556ee-7c69-4138-a152-b3fa16bb86b2"> <emphasis role="bold">Code Meaning</emphasis> </para> </th> <th align="center" colspan="1" rowspan="1"> <para xml:id="para_e0270183-1962-48d5-877f-b63624671b37"> <emphasis role="bold">Definition</emphasis> </para> </th> <th align="center" colspan="1" rowspan="1"> <para xml:id="para_5aa10e80-ebb2-45b9-a2a9-fe4b3eb4497c"> <emphasis role="bold">Notes</emphasis> </para> </th> </tr> </thead> <tbody> <tr valign="top"> <td align="center" colspan="1" rowspan="1"> <para xml:id="DCM_111026">111026</para> </td> <td align="left" colspan="1" rowspan="1"> <para xml:id="para_b64ae20f-fc2a-4cf1-90e1-9a81440f81a0">Horizontal Pixel Spacing</para> </td> <td align="left" colspan="1" rowspan="1"> <para xml:id="para_250c65d9-1035-4855-8e5a-044e37701a8d">For projection radiography, the horizontal physical distance measured at the front plane of an Image Receptor housing between the center of each pixel<emphasis role="bold"><emphasis role="underline"> (spacing between the centers of adjacent columns)</emphasis></emphasis>. For tomographic images, the horizontal physical distance in the patient between the center of each pixel.</para> </td> <td align="left" colspan="1" rowspan="1"> <para xml:id="para_49f6e571-7031-43d0-a033-4c6f6966ea0d"/> </td> </tr> <tr valign="top"> <td align="center" colspan="1" rowspan="1"> <para xml:id="DCM_111066">111066</para> </td> <td align="left" colspan="1" rowspan="1"> <para xml:id="para_b1a84523-137f-4db5-a5c2-877a786445e0">Vertical Pixel Spacing</para> </td> <td align="left" colspan="1" rowspan="1"> <para xml:id="para_a481db7b-70bc-42ad-aa27-03a7e9908931">For projection radiography, the vertical physical distance measured at the front plane of an Image Receptor housing between the center of each pixel<emphasis role="bold"><emphasis role="underline"> (spacing between the centers of adjacent rows)</emphasis></emphasis>. For tomographic images, the vertical physical distance in the patient between the center of each pixel.</para> </td> <td align="left" colspan="1" rowspan="1"> <para xml:id="para_1237eaf7-43ff-472e-85bd-647af8bbecc2"/> </td> </tr> </tbody> </table> </section> </chapter> </book>