DICOM structure

1. shijupk@gmail.com

3. igital maging and mmunication in edicine

4. DICOM File
Meta Info
DICOM
Dataset
File Preamble
Prefix
Data Element
Data Element
Data Element
Data Element
Data Element
*
*
*
128 Bytes (Set to 00H by default)
DICM
Attribute Name Tag Type
Group Length (0002, 0000) 1
File Meta InfoVersion (0002, 0001) 1
Media Storage SOP Class UID (0002, 0002) 1
Media Storage SOP Instance (0002, 0003) 1
Transfer Syntax UID (0002, 0010) 1
Implementation Class UID (0002, 0012) 1
ImplementationVersion Name (0002, 0013) 3
Source Application EntityTitle (0002, 0016) 3
Private Info Creator UID (0002, 0100) 3
Private Info (0002, 00102) 1C
Group 0002H elements are always encoded in ExplicitVR Little Endian

5. Data Element
Data Element
Data Element
Data Element
Data Element
*
*
*
Prefix
Preamble
ExplicitV R other than above
Element
Number
Group Number Value Length Value Field
2 bytes2 bytes 4bytes Value Length bytes
ImplicitV R
Element
Number
Group Number
Value
Representation
Value Length Value Field
2 bytes2 bytes 2 bytes 2 bytes Value Length bytes
ExplicitV R of OB, OW, OF, OD, SQ, UC, UR, UT or UN
Element
Number
Group Number
Value
Representation
Value Field
2 bytes2 bytes 2 bytes Value Length bytes
Reserved
2 bytes
Value Length
4 bytes

6. • Clinical data comes in a wide variety of formats.
• Ex. Distances measured in millimeters, time in seconds,
• patient names are typically written in alphabetic characters, and
so on.
• The DICOM standard defines 27 basic data types, known as value
representations (VRs),
• which are designed to encapsulate all possible clinical data types.
• EachVR has its own abbreviated two-letter name, a definition of
what it represents, a description of what characters are allowed in
its data, and a pre-scribed data length.

7. • Fixed FormatVR:
• DA: Date
• TM:Time
• DT: DateTime
• PN: Person Name
• OtherVR:
• OB: Other Byte
• OW: OtherWord
• OF: Other Float
• SQ: Sequence
• AE:Application Entity
• AS:Age String
• AT: AttributeTag
• OtherVR
•CS: Code String
•UI: Unique Identifier
•UN: Unknown

9. 01001000 01100101
01101100 01101100
01101111 00100000
01000100 01001001
01000011 01001111
01001101 00001010
Hello DICOM

10. • Store the most significant byte in the smallest address
• store the least significant byte in the smallest address
Address Value
1000 90
1001 AB
1002 12
1003 cd
Address Value
1000 CD
1001 12
1002 AB
1003 90

11. Transfer Syntax UID Transfer Syntax Name
1.2.840.10008.1.2 ImplicitVR Endian: DefaultTransfer Syntax for DICOM
1.2.840.10008.1.2.1 ExplicitVR Little Endian
1.2.840.10008.1.2.1.99 Deflated ExplicitVR Little Endian
1.2.840.10008.1.2.2 ExplicitVR Big Endian
Transfer Syntax UID Transfer Syntax Name
1.2.840.10008.1.2.4.50 JPEG Baseline (Process 1):
Default Transfer Syntax for Lossy JPEG 8-bit Image Compression
1.2.840.10008.1.2.4.51 JPEG Baseline (Processes 2 & 4):
Default Transfer Syntax for Lossy JPEG 12-bit Image Compression
1.2.840.10008.1.2.4.57 JPEG Lossless, Nonhierarchical (Processes 14)
1.2.840.10008.1.2.4.70 JPEG Lossless, Nonhierarchical, First-Order Prediction
DefaultTransfer Syntax for Lossless JPEG Image Compression
1.2.840.10008.1.2.4.80 JPEG-LS Lossless Image Compression
1.2.840.10008.1.2.4.81 JPEG-LS Lossy (Near- Lossless) Image Compression
1.2.840.10008.1.2.4.90 JPEG 2000 Image Compression (Lossless Only)
1.2.840.10008.1.2.4.91 JPEG 2000 Image Compression
1.2.840.10008.1.2.4.92 JPEG 2000 Part 2 Multicomponent Image Compression (Lossless Only)
1.2.840.10008.1.2.4.93 JPEG 2000 Part 2 Multicomponent Image Compression
1.2.840.10008.1.2.5 RLE Lossless
1.2.840.10008.1.2.4.94 JPIP Referenced
1.2.840.10008.1.2.4.95 JPIP Referenced Deflate
1.2.840.10008.1.2.6.1 RFC 2557 MIME Encapsulation
1.2.840.10008.1.2.4.100 MPEG2 Main Profile Main Level
1.2.840.10008.1.2.4.103 MPEG-4 AVC/H.264 BD-compatible High Profile / Level 4.1
1.2.840.10008.1.2.4.102 MPEG-4 AVC/H.264 High Profile / Level 4.1

12. SOP Class UID
SOP Instance UID
Patient Name
Patient ID
Patient Birth Date
Patient Sex
Study UID
Study Date
Study ID
Referring Physician
Accession Number
Series UID
Series Number
ModalityType
Manufacturer
Institution Name
Image UID
Image Number
ImageType
Image Pixel Attributes
Window widthWindow
Center
Patient
Study
Series Series Series
Image
Image
Image
Image
Image
Image
Image
Image
Image
Other Studies

13. Patient Entity
Study Entity
Series Entity
Image Entity
General Image
Attributes
Image Pixel
Attributes
Samples per Pixel
Photometric Interpretation
Rows
Columns
BitsAllocated
Bits Stored
Pixel Representation
Pixel Data
Planar Configuration

14. Samples per Pixel
Photometric Interpretation
Rows
Columns
BitsAllocated
Bits Stored
Pixel Representation
Pixel Data
Planar Configuration
Un used
BitsAllocated
Pixel Cell
High Bit
High Bit
Un used Pixel Cell Un used Pixel Cell
Pixel Data Stream
Pixel Sample
0111215
BitsAllocated = 16
Bits Stored = 12
High bit = 11

15. Pixel Cell
Pixel sample
value
Pixel sample
value
Pixel sample
value
Pixel sample
value
Pixel sample
value
Pixel sample
value
….. …. …. …..
…. …. …. … …
…. …. …. …
…. …. …. … …
…. …. …. … …
Rows
Columns

16. Pixel data Apply LUT Render
WindowWidth /Window Center
where x is the input value, y is an output value with a range
from y min to y max
c isWindow Center (0028,1050) and w isWindow
Width (0028,1051):
If (x <= c - 0.5 - (w-1)/2), then y = y min
else if (x > c - 0.5 + (w-1)/2), then y = y max ,
else y = ((x - (c - 0.5)) / (w-1) + 0.5) * (y max - y min )+ y min
VOILUT Function
SIGMOID Descriptor
If the value ofVOI LUT Function (0028,1056) is SIGMOID, the function to be
used to convert the output of the (conceptual) Modality LUT values to the
input of the (conceptual) Presentation LUT is given by
OUT =
𝑜𝑢𝑡𝑝𝑢𝑡_𝑟𝑎𝑛𝑔𝑒
1+exp(−4
𝐼𝑁 −𝑊𝐶
𝑊𝑊
where
IN is the input value of the LUT (i.e., the output of the (conceptual) Modality LUT).
WC (resp. WW) is the Window Center (resp. Window Width) defined interactively by the user
or by using the values provided in (0028,1050) (resp. 0028,1051).
Output_range is the maximum output value

17. Questions are the answers!