| DICOM PS3.3 2024e - Information Object Definitions |
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The following Image IE Modules are common to all Composite Image IODs that reference the Image IE.
Table C.7-9 specifies the Attributes of the General Image Module, which identify and describe an image within a particular Series.
Table C.7-9. General Image Module Attributes
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Patient direction of the rows and columns of the image. Required if image does not require Image Orientation (Patient) (0020,0037) and Image Position (Patient) (0020,0032) or if image does not require Image Orientation (Slide) (0048,0102). May be present otherwise. See Section C.7.6.1.1.1 for further explanation. |
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The date the image pixel data creation started. Required if image is part of a Series in which the images are temporally related. May be present otherwise. |
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The time the image pixel data creation started. Required if image is part of a Series in which the images are temporally related. May be present otherwise. |
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Image identification characteristics. See Section C.7.6.1.1.2 for Defined Terms and further explanation. |
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Indicates whether or not quality control material (such as calibration or control material, or a phantom) is present in this image. Enumerated Values: If this Attribute is absent, then the image may or may not be a quality control or phantom image. The phantom device or quality control material in the image can be described using the Device Module. See Section C.7.6.12. |
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Indicates whether or not image contains sufficient burned in annotation to identify the patient and date the image was acquired. If this Attribute is absent, then the image may or may not contain burned in annotation. |
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Indicates whether or not the image contains sufficiently recognizable visual features to allow the image or a reconstruction from a set of images to identify the Patient. If this Attribute is absent, then the image may or may not contain recognizable visual features. |
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Specifies whether an Image has undergone lossy compression (at a point in its lifetime). Enumerated Values: Once this value has been set to "01" it shall not be reset. See Section C.7.6.1.1.5. |
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Describes the approximate lossy compression ratio(s) that have been applied to this image. |
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A label for the lossy compression method(s) that have been applied to this image. |
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See Section C.7.6.1.1.6 for further explanation. |
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When present, specifies an identity transformation for the Presentation LUT such that the output of all grayscale transformations, if any, are defined to be in P-Values. Enumerated Values: When this Attribute is used with a color photometric interpretation then the luminance component is in P-Values. |
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The mapping of stored values to associated Real World values. |
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>Include Table C.7.6.16-12b “Real World Value Mapping Item Macro Attributes” |
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Laterality of (possibly paired) body part (as described in Anatomic Region Sequence (0008,2218)) examined. Shall be consistent with any laterality information contained in Primary Anatomic Structure Modifier Sequence (0008,2230) and/or Laterality (0020,0060), if present. |
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Include Table 10-7 “General Anatomy Optional Macro Attributes” |
Anatomic Region Sequence BCID 4031 “Common Anatomic Region” for humans. Anatomic Region Sequence BCID 7483 “Common Anatomic Regions for Animal” for non-human organisms. |
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Previous releases 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.
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.
If Anatomical Orientation Type (0010,2210) is absent or has a value of BIPED, anatomical direction shall be designated by abbreviations using the capital letters:
If Anatomical Orientation Type (0010,2210) has a value of QUADRUPED, anatomical direction shall be designated by the abbreviations using capital letters:
These abbreviations are capitalized versions of those defined in Smallwood et al for describing radiographic projections. Because of the Code String (CS) Value Representation of Patient Orientation (0020,0020), lowercase letters cannot be used.
It is unfortunate that the conventional veterinary abbreviations (e.g., R for rostral and Rt for right) differ from those chosen for humans for DICOM usage (e.g., R for right), but confusion with in the respective human and non-human organism domains will be reduced. Hanging protocols may need to account for the difference by checking for the correct species.
Smallwood et al define an O (Oblique) abbreviation, which is useful for describing radiographic projections, but do not specify its use for directional terms, and hence it is not included here for describing the row and column directions.
The terms "anterior" and "posterior" are commonly used in vertebrate zoology to describe the cranial and caudal directions respectively, the veterinary terms are used in preference here, also in order to avoid confusion with the contradictory human use of anterior and posterior to mean ventral and dorsal.
For non-human organisms other than quadrupeds, for example, birds and fish, it is anticipated that the same nomenclature can be logically extended to describe, for example, wings and fins.
Each value of the orientation Attribute shall contain at least one of these abbreviations. If refinements in the orientation descriptions are to be specified, then they shall be designated by one or two additional abbreviations in each value. Within each value, the abbreviations shall be ordered with the principal orientation designated in the first abbreviations.
For bipeds, since each abbreviation is a single character, no delimiter is required within a single value and none is used. For quadrupeds, though lowercase letters cannot be used, delimiters are not necessary within a single value to eliminate ambiguity, since the abbreviations used are sufficiently distinct, and can be parsed from left to right with a single character of lookahead.
E.g., a medio-lateral oblique projection of the left breast of a human might be encoded with Patient Orientation values of "A\FR" rather than "A\F", since the plane is obliquely inclined such that the columns are directed both downwards and medially, which for a left breast is towards the right, though the downwards direction is the principal column orientation.
E.g., a right dorsal-left ventral oblique view of a quadruped's abdomen might be encoded with Patient Orientation values of "LEV\CD", rather than "LE\CD", since the plane is obliquely inclined such that the rows are directed both to the left and ventrally, though the left direction is the principal row orientation. The abbreviations "LEV", "LE" and "CD", correspond to the designations in Smallwood et al of "LeV", "Le" and "Cd", respectively
Image Type (0008,0008) identifies important image identification characteristics. These characteristics are:
The Image Type Attribute is multi-valued and shall be provided in the following manner:
Any of the optional values (value 3 and beyond) may be encoded either with a value or zero-length, independent of other optional values, unless otherwise specified by a specialization of this Attribute in an IOD.
If the pixel data of the derived Image is different from the pixel data of the source images and this difference is expected to affect professional interpretation of the image, the Derived Image shall have a SOP Instance UID (0008,0018) different than all the source images.
See Section C.12.4.1.1.
Source Image Sequence (0008,2112) was formerly used in this Module but has been moved to the General Reference Module. See Section C.12.4.1.2 “Source Image Sequence”.
The Attribute Lossy Image Compression (0028,2110) conveys that the Image has undergone lossy compression. It provides a means to record that the Image has been compressed (at a point in its lifetime) with a lossy algorithm and changes have been introduced into the pixel data. Once the value has been set to "01", it shall not be reset.
If an image is compressed with a lossy algorithm, the Attribute Lossy Image Compression (0028,2110) is set to "01". Subsequently, if the image is decompressed and transferred in uncompressed format, this Attribute value remains "01".
The value of Lossy Image Compression (0028,2110) in SOP Instances containing multiple frames in which one or more of the frames have undergone lossy compression shall be "01".
It is recommended that the applicable frames be noted in the Attribute Derivation Description (0008,2111).
If an image is originally obtained as a lossy compressed image from the sensor, then Lossy Image Compression (0028,2110) is set to "01" and Value 1 of the Attribute Image Type (0008,0008) shall be set to ORIGINAL.
If an image is a compressed version of another image, Lossy Image Compression (0028,2110) is set to "01", Value 1 of the Attribute Image Type (0008,0008) shall be set to DERIVED, and if the predecessor was a DICOM image, then the Image shall receive a new SOP Instance UID.
It is recommended that the approximate compression ratio be provided in the Attribute Derivation Description (0008,2111). Furthermore, it is recommended that Derivation Description (0008,2111) be used to indicate when pixel data changes might affect professional interpretation (see Section C.12.4.1.1).
The Attribute Lossy Image Compression (0028,2110) is defined as Type 3 for backward compatibility with existing IODs. It is expected to be required (i.e., defined as Type 1C) for new Image IODs and for existing IODs that undergo a major revision (e.g., a new IOD is specified).
Lossy Image Compression Method (0028,2114) may be multi-valued if successive lossy compression steps have been applied; the value order shall correspond to the values of Lossy Image Compression Ratio (0028,2112), if present.
Defined Terms for Lossy Image Compression Method (0028,2114):
JPEG Lossy Compression [ISO/IEC 10918-1]
JPEG-LS Near-lossless Compression [ISO/IEC 14495-1]
JPEG 2000 Irreversible Compression [ISO/IEC 15444-1]
High-Throughput JPEG 2000 Irreversible Compression [ISO/IEC 15444-15]
JPEG XL Image Coding System - Part 1 Core Coding System [ISO/IEC 18181-1]
MPEG2 Compression [ISO/IEC 13818-2]
MPEG-4 AVC/H.264 Compression [ISO/IEC 14496-10]
HEVC/H.265 Lossy Compression [ISO/IEC 23008-2]
The value of the "compression ratio" is encoded as a numeric value that represents the numerator of an implicit ratio in which the denominator is always one, consistent with the traditional representation in the literature.
The value may be an estimate (e.g., the nominal value that is supplied to the compressor), or it may be a measured value (e.g., computed by dividing the uncompressed pixel data size by the size of the compressed bit stream).
Lossy Image Compression Ratio (0028,2112) may be multi-valued if successive lossy compression steps have been applied; if so, the value order shall correspond to the multiple values of Lossy Image Compression Method (0028,2114), if present.
An Icon Image may be used as a key representative of an Image. It is defined as a Sequence that contains a single Item encapsulating the Data Set made of the Data Elements of the Icon Image. The Data Elements are defined by the Section C.7.6.3.2 Image Pixel Macro. Unless otherwise specified in the Module or Macro table where the Icon Image Sequence (0088,0200) is used, the following restrictions shall apply on the Image Pixel Macro usage:
Only monochrome and palette color images shall be used. Samples per Pixel (0028,0002) shall have a Value of 1, Photometric Interpretation (0028,0004) shall have a Value of either MONOCHROME 1, MONOCHROME 2 or PALETTE COLOR, Planar Configuration (0028,0006) shall not be present.
There is no explicit limitation on the size of an Icon Image specified by Rows (0028,0010) and Columns (0028,0011).
Pixel samples shall have a Value of either 1 or 8 for Bits Allocated (0028,0100) and Bits Stored (0028,0101). High Bit (0028,0102) shall have a Value of one less than the Value used in Bit Stored.
Pixel Representation (0028,0103) shall specify an unsigned integer representation (Value 0000H).
the pixels shall be square (i.e., their aspect ratio shall be 1:1) and therefore Pixel Aspect Ratio (0028,0034) shall not be present.
If a Palette Color lookup Table is used, Bits Allocated (0028,0100) shall have a Value of 8.
See Section C.7.10.1.1.1.
| DICOM PS3.3 2024e - Information Object Definitions |
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