| | DICOM Terms and Abbreviations |
V&V: Verification and Validation.
VF: Abbreviation for a type of modality: Videofluorography.
VL: Abbreviation for a type of modality: Visable Light.
VM: Value Multiplicity, defining whether or not an attribute can have multiple elements, for example multiple phone numbers.
VOI LUT: Value Of Interest Look Up Table, defining the mapping to the image pixel data resulting in the information that one is interested in. Also described by Window width and Center, when linear.
VR: Value
Representation, the definition of
rules and encoding of groups of similar
attributes. An example is the VR PN, Person Name which
specifies exactly the sequence of the
last name, first etc, max number of
characters, character repertoire, etc.
As part of the negotiation, one can
agree on Explicit or
Implicit VR
encoding.
Currently known Value Representations are:
AE: Application Entity,
AS: Age String,
AT: Attribute Tag,
CS: Code String,
DA: Date,
DS: Decimal String,
DT: Date/Time,
FL: Floating Point Single,
FD: Floating Point Double,
IS: Integer String,
LO: Long String,
LT: Long Text,
OB: Other Byte String,
OW: Other Word String,
PN: Person Name,
SH: Short String,
SL: Signed Long,
SQ: Sequence of Items,
SS: Signed Short,
ST: Short Text,
TM: Time,
UI: Unique Identifier,
UL: Unsigned Long and
US: Unsigned Short.
Value Representation "Application Entity"
A string of characters with leading and trailing
spaces (20H) being non-significant. The value made of 16 spaces,
meaning "no application name specified", shall not be
used.
Character Set: Default Character Repertoire excluding control
characters LF, FF, CR and ESC.
Size Restriction(s): 16 bytes maximum
Value Representation "Age String"
A string of characters with one of the following
formats -- nnnD, nnnW, nnnM, nnnY; where nnn shall contain the
number of days for D, weeks for W, months for M, or years for Y.
Example: "018M" would represent an age of 18
months.
Character Set: "0"-"9", "D",
"W", "M", "Y" of Default Character
Repertoire
Size Restriction(s): 4 bytes fixed
Value Representation "Attribute Tag"
Ordered pair of 16-bit unsigned integers that is
the value of a Data Element Tag. Example: A Data Element Tag of
(0018,00FF) would be encoded as a series of 4 bytes in a
Little-Endian Transfer Syntax as 18H,00H,FFH,00H and in a
Big-Endian Transfer Syntax as 00H,18H,00H,FFH.
Note:
The encoding
of an AT value is exactly the same as the encoding of a Data
Element Tag as defined in Section 7.
Character Set: not applicable
Size Restriction(s): 4 bytes fixed
Value Representation "Code String"
A string of characters with leading or trailing
spaces (20H) being non-significant.
Character Set: Uppercase characters, "0"-"
9", the SPACE character, and underscore "_", of
the Default Character Repertoire
Size Restriction(s): 16 bytes maximum
Value Representation "Date"
A string of characters of the format yyyymmdd;
where yyyy shall contain year, mm shall contain the month, and dd
shall contain the day. This conforms to the ANSI HISPP MSDS Date
common data type.
Example: "19930822" would represent
August 22, 1993.
Notes:
1. For reasons of backward compatibility
with versions of this standard prior to V3.0, it is recommended
that implementations also support a string of characters of the
format yyyy.mm.dd for this VR.
2. See also DT VR in this table.
Character Set: "0"-"9" of Default Character
Repertoire
Note:
For reasons specified in the previous column,
implementations may wish to support the "." character
as well.
Size Restriction(s): 8 bytes fixed
Note:
For reasons specified in the
previous columns, implementations may also wish to support a 10
byte fixed length as well.
Value Representation "Decimal String"
A string of characters representing either a fixed
point number or a floating point number. A fixed point number
shall contain only the characters 0-9 with an optional leading
"+" or "-" and an optional "." to
mark the decimal point. A floating point number shall be conveyed
as defined in ANSI X3.9, with an "E" or "e"
to indicate the start of the exponent. Decimal Strings may be
padded with leading or trailing spaces. Embedded spaces are not
allowed.
Character Set: "0"-"9", "+",
"-", "E", "e", "." of
Default Character Repertoire
Size Restriction(s): 16 bytes maximum
Value Representation "Date Time"
The Date Time common data type. Indicates a
concatenated date-time ASCII string in the format:
CCYYMMDDHHMMSS.FFFFFF&ZZZZ The components of this string,
from left to right, are CC = Century, YY = Year, MM = Month, DD =
Day, HH = Hour, MM = Minute, SS = Second, FFFFFF = Fractional
Second, & = "+" or "-", and ZZZZ = Hours
and Minutes of offset. &ZZZZ is an optional suffix for
plus/minus offset from Coordinated Universal Time. A component
that is omitted from the string is termed a null component.
Trailing null components of Date Time are ignored. Non-trailing
null components are prohibited, given that the optional suffix is
not considered as a component.
Note:
For reasons of backward
compatibility with versions of this standard prior to V3.0, many
existing DICOM Data Elements use the separate DA and TM VRs.
Standard and Private Data Elements defined in the future should
use DT, when appropriate, to be more compliant with ANSI HISPP
MSDS.
Character Set: "0"-"9", "+",
"-", "." of Default Character Repertoire
Size Restriction(s): 26 bytes maximum
Value Representation "Floating Point Double"
Double precision binary floating point number
represented in IEEE 754:1985 64-bit Floating Point Number
Format.
Character Set: not applicable
Size Restriction(s): 8 bytes fixed
Value Representation "Floating Point Single"
Single precision binary floating point number
represented in IEEE 754:1985 32-bit Floating Point Number
Format.
Character Set: not applicable
Size Restriction(s): 4 bytes fixed
Value Representation "Integer String"
A string of characters representing an Integer in
base-10 (decimal), shall contain only the characters 0 - 9, with
an optional leading "+" or "-". It may be
padded with leading and/or trailing spaces. Embedded spaces are
not allowed. The integer, n, represented shall be in the range:
-(231 - 1 ) <= n <= (231 - 1).
Character Set: "0"-"9", "+",
"-" of Default Character Repertoire
Size Restriction(s): 12 bytes maximum
Value Representation "Long String"
A character string that may be padded withleading
and/or trailing spaces. The character code 5CH (the BACKSLASH
"\" in ISO-IR 6) shall not be present, as it is used as
the delimiter between values in multiple valued data elements.
The string shall not have Control Characters except for ESC.
Character Set: Default Character Repertoire and/or as defined by
(0008,0005).
Size Restriction(s): 64 chars maximum (see NOTE in 6.2)
Value Representation "Long Text"
A character string that may contain one or more
paragraphs. It may contain the Graphic Character set and the
Control Characters, CR, LF, FF, and ESC. It may be padded with
trailing spaces, which may be ignored, but leading spaces are
considered to be significant. Data Elements with this VR shall
not be multi-valued and therefore character code 5CH (the
BACKSLASH "\" in ISO-IR 6) may be used.
Character Set: Default Character Repertoire and/or as defined by
(0008,0005).
Size Restriction(s): 10240 chars maximum (see NOTE in 6.2)
Value Representation "Other Byte String"
A string of bytes where the encoding of the
contents is specified by the negotiated Transfer Syntax. OB is a
VR which is insensitive to Little/Big Endian byte ordering (see
Section 7.3). The string of bytes shall be padded with a single
trailing NULL byte value (00H) when necessary to achieve even
length.
Character Set: not applicable
Size Restriction(s): see Transfer Syntax definition
Value Representation "Other Word String"
A string of 16-bit words where the encoding of the
contents is specified by the negotiated Transfer Syntax. OW is a
VR which requires byte swapping within each word when changing
between Little Endian and Big Endian byte ordering (see Section
7.3).
Character Set: not applicable
Size Restriction(s): see Transfer Syntax definition
Value Representation "Person Name"
A character string encoded using a 5 component
convention. The character code 5CH (the BACKSLASH "\"
in ISO-IR 6) shall not be present, as it is used as the delimiter
between values in multiple valued data elements. The string may
be padded with trailing spaces. The five components in their
order of occurrence are: family name complex, given name complex,
middle name, name prefix, name suffix. Any of the five components
may be an empty string. The component delimiter shall be the
caret "^" character (5EH). Delimiters are required for
interior null components. Trailing null components and their
delimiters may be omitted. Multiple entries are permitted in each
component and are encoded as natural text strings, in the format
preferred by the named person. This conforms to the ANSI HISPP
MSDS Person Name common data type.
This group of five components
is referred to as a Person Name component group.
For the purpose
of writing names in ideographic characters and in phonetic
characters, up to 3 groups of components (see Annex H examples 1
and 2) may be used. The delimiter for component groups shall be
the equals character "=" (3DH). The three component
groups of components in their order of occurrence are: a
single-byte character representation, an ideographic
representation, and a phonetic representation.
Any component
group may be absent, including the first component group. In this
case, the person name may start with one or more "="
delimiters. Delimiters are required for interior null component
groups. Trailing null component groups and their delimiters may be
omitted.
Precise semantics are defined for each component group.
See section 6.2.1.
Examples:
Rev. John Robert Quincy Adams, B.A. M.Div.
"Adams^John Robert Quincy^^Rev.^B.A. M.Div."
[One family name; three given names; no middle name; one prefix;
two suffixes.]
Susan Morrison-Jones, Ph.D., Chief Executive Officer
"Morrison-Jones^Susan^^^Ph.D., Chief Executive
Officer"
[Two family names; one given name; no middle name;
no prefix; two suffixes.]
John Doe
"Doe^John"
[One family name; one given name; no middle name, prefix, or suffix.
Delimiters have been omitted for the three trailing null
components.]
(For examples of the encoding of Person Names using
multi-byte character sets see Annex H)
Notes
1. This five
component convention is also used by HL7 as defined in ASTM
E-1238-91 and further specialized by the ANSI MSDS.
2. In typical
American and European usage the first occurrence of "given
name" would represent the "first name". The second
and subsequent occurrences of the "given name" would
typically be treated as a middle name(s). The "middle
name" component is retained for the purpose of backward
compatibility with existing standards.
3. The "Degree"
component present in ASTM E-1238-91 is absorbed into the
"Suffix" component.
4. The implementor should remain
mindful of earlier usage forms which represented "given
names" as "first" and "middle" and that
translations to and from this previous typical usage may be
required.
5. For reasons of backward compatibility with versions
of this standard prior to V3.0, person names might be considered
a single family name complex (single component without
"^" delimiters).
Character Set: Default Character Repertoire and/or as defined by
(0008,0005) excluding Control Characters LF, FF, and CR but
allowing Control Character ESC.
Size Restriction(s): 64 chars maximum per component group (see NOTE in
6.2)
Value Representation "Short String"
A character string that may be padded with leading
and/or trailing spaces. The character code 05CH (the BACKSLASH
"\" in ISO-IR 6) shall not be present, as it is used as
the delimiter between values for multiple data elements. The
string shall not have Control Characters except ESC.
Character Set: Default Character Repertoire and/or as defined by
(0008,0005).
Size Restriction(s): 16 chars maximum (see NOTE in 6.2)
Value Representation "Signed Long"
Signed binary integer 32 bits long. Represents an
integer, n, in the range:
- (231 - 1 ) <= n <= (231 - 1).
Character Set: not applicable
Size Restriction(s): 4 bytes fixed
Value Representation "Sequence of Items"
Value is a Sequence of zero or more Items, as
defined in Section 7.5.
Character Set: not applicable (see Section 7.5)
Size Restriction(s): not applicable (see Section 7.5)
Value Representation "Signed Short"
Signed binary integer 16 bits long in 2's
complement form. Represents an integer n in the range:
- (215 - 1 ) <= n <= (215 - 1).
Character Set: not applicable
Size Restriction(s): 2 bytes fixed
Value Representation "Short Text"
A character string that may contain one or more
paragraphs. It may contain the Graphic Character set and the
Control Characters, CR, LF, FF, and ESC. It may be padded with
trailing spaces, which may be ignored, but leading spaces are
considered to be significant. Data Elements with this VR shall
not be multi-valued and therefore character code 5CH (the
BACKSLASH "\" in ISO-IR 6) may be used.
Character Set: Default Character Repertoire and/or as defined by
(0008,0005).
Size Restriction(s): 1024 chars maximum (see NOTE in 6.2)
Value Representation "Time"
A string of characters of the format hhmmss.frac;
where hh contains hours (range "00" - "23"),
mm contains minutes (range "00" - "59"), ss
contains seconds (range "00" - "59"), and
frac contains a fractional part of a second as small as 1
millionth of a second (range "000000" -
"999999"). A 24 hour clock is assumed. Midnight can be
represented by only "0000" since "2400" would
violate the hour range. The string may be padded with trailing
spaces. Leading and embedded spaces are not allowed. One or more
of the components mm, ss, or frac may be unspecified as long as
every component to the right of an unspecified component is also
unspecified. If frac is unspecified the preceding "."
may not be included. Frac shall be held to six decimal places or
less to ensure its format conforms to the ANSI HISPP MSDS Time
common data type.
Examples:
1. "070907.0705 "
represents a time of 7 hours, 9 minutes and 7.0705 seconds.
2. "1010" represents a time of 10 hours, and 10 minutes.
3. "021 " is an invalid value.
Notes
1. For reasons of
backward compatibility with versions of this standard prior to
V3.0, it is recommended that implementations also support a
string of characters of the format hh:mm:ss.frac for this VR.
2. See also DT VR in this table.
Character Set: "0"-"9", "." of
Default Character Repertoire
Size Restriction(s): 16 bytes maximum
Value Representation "Unique Identifier (UID)"
A character string containing a UID that is used
to uniquely identify a wide variety of items. The UID is a series
of numeric components separated by the period "."
character. If a Value Field containing one or more UIDs is an odd
number of bytes in length, the Value Field shall be padded with a
single trailing NULL (00H) character to ensure that the Value
Field is an even number of bytes in length. See Section 9 and
Annex B for a complete specification and examples.
Character Set: "0"-"9", "." of
Default Character Repertoire
Size Restriction(s): 64 bytes maximum
Value Representation "Unsigned Long"
Unsigned binary integer 32 bits long. Represents
an integer n in the range:
0 <= n < 232.
Character Set: not applicable
Size Restriction(s): 4 bytes fixed
Value Representation "Unknown"
A string of bytes where the encoding of the
contents is unknown (see Section 6.2.2).
Character Set: not applicable
Size Restriction(s): Any length valid for any of the other DICOM Value
Representations
Value Representation "Unsigned Short"
Unsigned binary integer 16 bits long. Represents
integer n in the range:
0 <= n < 216.
Character Set: not applicable
Size Restriction(s): 2 bytes fixed
Value Representation "Unlimited Text"
A character string that may contain one or more
paragraphs. It may contain the Graphic Character set and the
Control Characters, CR, LF, FF, and ESC. It may be padded with
trailing spaces, which may be ignored, but leading spaces are
considered to be significant. Data Elements with this VR shall
not be multi-valued and therefore character code 5CH (the
BACKSLASH "\" in ISO-IR 6) may be used.
Character Set: Default Character Repertoire and/or as defined by
(0008,0005).
Size Restriction(s): 232 - 2
Note:
limited only by the size
of the maximum unsigned integer representable in a 32 bit VL field
minus one, since FFFFFFFFH is reserved.
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Parts of this document are taken (with permission) from Herman Oosterwijk's "DICOM Expert" Cheat Sheet © Copyright OTech, Inc. P.O. Box 260637 Plano, Texas 75026 herman@otechimg.com |