Материал: part03

IfAnatomicalOrientationType(0010,2210)isabsentorhasavalueofBIPED,anatomicaldirectionshallbedesignatedbyabbreviations​ using the capital letters:​

•​A (anterior)​

•​P (posterior)​

•​R (right)​

•​L (left)​

•​H (head)​

•​F (foot)​

IfAnatomicalOrientationType(0010,2210)hasavalueofQUADRUPED,anatomicaldirectionshallbedesignatedbytheabbreviations​ using capital letters:​

•​LE (Le or Left)​

•​RT (Rt or Right)​

•​D (Dorsal)​

•​V (Ventral)​

•​CR (Cr or Cranial)​

•​CD (Cd or Caudal)​

•​R (Rostral)​

•​M (Medial)​

•​L (Lateral)​

•​PR (Pr or Proximal)​

•​DI (Di or Distal)​

•​PA (Pa or Palmar)​

•​PL (Pl or Plantar)​

Note​

1.​TheseabbreviationsarecapitalizedversionsofthosedefinedinSmallwoodetalfordescribingradiographicprojections.​ Because of the Code String (CS) Value Representation of Patient Orientation (0020,0020), lowercase letters cannot be​ used.​

2.​Itisunfortunatethattheconventionalveterinaryabbreviations(e.g.,RforrostralandRtforright)differfromthosechosen​ for humans for DICOM usage (e.g., R for right), but confusion with in the respective human and animal domains will be​ reduced. Hanging protocols may need to account for the difference by checking for the correct species.​

3.​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.​

4.​Theterms"anterior"and"posterior"arecommonlyusedinvertebratezoologytodescribethecranialandcaudaldirections​ 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.​

5.​For animals other than quadrupeds, for example, birds and fish, it is anticipated that the same nomenclature can be lo-​ gically extended to describe, for example, wings and fins.​

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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 abbre-​ viations shall be ordered with the principal orientation designated in the first abbreviations.​

Note​

1.​For bipeds, since each abbreviation is a single character, no delimiter is required within a single value and none is used.​ Forquadrupeds,thoughlowercaseletterscannotbeused,delimitersarenotnecessarywithinasinglevaluetoeliminate​ ambiguity, since the abbreviations used are sufficiently distinct, and can be parsed from left to right with a single char-​ acter of lookahead.​

2.​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 orient-​ ation.​

3.​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​ andventrally,thoughtheleftdirectionistheprincipalroworientation.Theabbreviations"LEV","LE"and"CD",correspond​ to the designations in Smallwood et al of "LeV", "Le" and "Cd", respectively​

C.7.6.1.1.2 Image Type​

Image Type (0008,0008) identifies important image identification characteristics. These characteristics are:​

a.​Pixel Data Characteristics​

1.​is the image an ORIGINAL Image; an image whose pixel values are based on original or source data​

2.​is the image a DERIVED Image; an image whose pixel values have been derived in some manner from the pixel value of​ one or more other images​

b.​Patient Examination Characteristics​

1.​is the image a PRIMARY Image; an image created as a direct result of the patient examination​

2.​is the image a SECONDARY Image; an image created after the initial patient examination​

c.​Modality Specific Characteristics​

d.​Implementationspecificidentifiers;otherimplementationspecificidentifiersshallbedocumentedinanimplementation'sconformance​ statement.​

The Image Type Attribute is multi-valued and shall be provided in the following manner:​

a.​Value 1 shall identify the Pixel Data Characteristics​

Enumerated Values:​

ORIGINAL​identifies an Original Image​

DERIVED​ identifies a Derived Image​

b.​Value 2 shall identify the Patient Examination Characteristics​

Enumerated Values:​

PRIMARY​ identifies a Primary Image​

SECONDARY​identifies a Secondary Image​

c.​Value 3 shall identify any Image IOD specific specialization (optional)​

d.​Other Values that are implementation specific (optional)​

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.​

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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 UID different than all the source images.​

C.7.6.1.1.3 Derivation Description​

See Section C.12.4.1.1.​

C.7.6.1.1.4 Source Image Sequence​

Source Image Sequence (0008,2112) was formerly used in this Module but has been move to the General Reference Module. See​ Section C.12.4.1.2 “Source Image Sequence”.​

C.7.6.1.1.5 Lossy Image Compression​

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.​

Note​

If an image is compressed with a lossy algorithm, the Attribute Lossy Image Compression (0028,2110) is set to "01". Sub-​ sequently, 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".​

Note​

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.​

Note​

1.​ItisrecommendedthattheapproximatecompressionratiobeprovidedintheAttributeDerivationDescription(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).​

2.​TheAttributeLossyImageCompression(0028,2110)isdefinedasType3forbackwardcompatibilitywithexistingIODs.​ 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).​

C.7.6.1.1.5.1 Lossy Image Compression Method​

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):​

ISO_10918_1​ JPEG Lossy Compression [ISO/IEC 10918-1]​

ISO_14495_1​ JPEG-LS Near-lossless Compression [ISO/IEC 14495-1]​

ISO_15444_1​ JPEG 2000 Irreversible Compression [ISO/IEC 15444-1]​

ISO_13818_2​ MPEG2 Compression [ISO/IEC 13818-2]​

ISO_14496_10​ MPEG-4 AVC/H.264 Compression [ISO/IEC 14496-10]​

ISO_23008_2​ HEVC/H.265 Lossy Compression [ISO/IEC 23008-2]​

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C.7.6.1.1.5.2 Lossy Image Compression Ratio​

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.​

Note​

For example, a compression ratio of 30:1 would be described with a value of 30.​

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.​

Note​

For historical reasons, the lossy compression ratio should also be described in Derivation Description (0008,2111).​

C.7.6.1.1.6 Icon Image Sequence​

AnIconImagemaybeusedasakeyrepresentativeofanImage.ItisdefinedasaSequencethatcontainsasingleItemencapsulating​ the Data Set made of the Data Elements of the Icon Image. The Data Elements are defined by the Image Pixel Macro (see Sec-​ tion C.7.6.3). Unless otherwise specified in the Module or Macro table where the Icon Image Sequence (0088,0200) is used, the fol-​ lowing restrictions shall apply on the Image Pixel Macro usage:​

a.​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.​

Note​

True color icon images are not supported. This is due to the fact that the reduced size of the Icon Image makes the​ quality of a palette color image (with 256 colors) sufficient in most cases.​

b.​There is no explicit limitation on the size of an Icon Image specified by Rows (0028,0010) and Columns (0028,0011).​

c.​PixelsamplesshallhaveaValueofeither1or8forBitsAllocated(0028,0100)andBitsStored(0028,0101).HighBit(0028,0102)​ shall have a Value of one less than the Value used in Bit Stored.​

d.​Pixel Representation (0028,0103) shall specify an unsigned integer representation (Value 0000H).​

e.​Pixel Aspect Ratio (0028,0034) shall have a Value of 1:1.​

f.​ If a Palette Color lookup Table is used, Bits Allocated (0028,0100) shall have a Value of 8.​

C.7.6.1.1.7 Irradiation Event UID​

An irradiation event is the loading of X-Ray equipment caused by a single continuous actuation of the equipment's irradiation switch,​ from the start of the loading time of the first pulse until the loading time trailing edge of the final pulse. Any on-off switching of the irra-​ diation source during the event shall not be treated as separate events, rather the event includes the time between start and stop of​ irradiation as triggered by the user. E.g., a pulsed fluoro X-Ray acquisition shall be treated as a single irradiation event.​

C.7.6.2 Image Plane Module​

Table C.7-10 specifies the Attributes that define the transmitted pixel array of a two dimensional image plane.​

Note​

In previous versions of this Standard, image position and image orientation were specified relative to a specific equipment​ coordinate system. This equipment coordinate system was not fully defined and a number of ambiguities existed. The​ Equipment-Based Coordinate System has been retired and replaced by the Patient-Based Coordinate System defined in​ this Module.​

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Page 520​ DICOM PS3.3 2020a - Information Object Definitions​

Table C.7-10. Image Plane Module Attributes​

C.7.6.2.1 Image Plane Attribute Descriptions​

C.7.6.2.1.1 Image Position and Image Orientation​

Image Position (0020,0032) specifies the x, y, and z coordinates of the upper left hand corner of the image; it is the center of the first​ voxel transmitted. Image Orientation (0020,0037) specifies the direction cosines of the first row and the first column with respect to​ the patient. These Attributes shall be provide as a pair. Row value for the x, y, and z axes respectively followed by the Column value​ for the x, y, and z axes respectively.​

The direction of the axes is defined fully by the patient's orientation.​

If Anatomical Orientation Type (0010,2210) is absent or has a value of BIPED, the x-axis is increasing to the left hand side of the​ patient. The y-axis is increasing to the posterior side of the patient. The z-axis is increasing toward the head of the patient.​

If Anatomical Orientation Type (0010,2210) has a value of QUADRUPED, the​

•​x-axis is increasing to the left (as opposed to right) side of the patient​

•​the y-axis is increasing towards​

•​the dorsal (as opposed to ventral) side of the patient for the neck, trunk and tail,​

•​the dorsal (as opposed to ventral) side of the patient for the head,​

•​the dorsal (as opposed to plantar or palmar) side of the distal limbs,​

•​the cranial (as opposed caudal) side of the proximal limbs, and​

•​the z-axis is increasing towards​

•​the cranial (as opposed to caudal) end of the patient for the neck, trunk and tail,​

•​the rostral (as opposed to caudal) end of the patient for the head, and​

•​the proximal (as opposed to distal) end of the limbs​

Note​

1.​The axes for quadrupeds are those defined and illustrated in Smallwood et al for proper anatomic directional terms as​ they apply to various parts of the body.​

2.​Itshouldbeanticipatedthatwhenquadrupedsareimagedonhumanequipment,andparticularlywhentheyareposition​ in a manner different from the traditional human prone and supine head or feet first longitudinal position, then the​ equipment may well not indicate the correct orientation, though it will remain an orthogonal Cartesian right-handed​ system that could be corrected subsequently.​

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