exchanging imaging data
DESCRIPTION
Exchanging Imaging Data. Cor Loef Philips. Exchanging Imaging Data. Objective: This presentation will answer the following question: What are the types of DICOM objects and how do we move them around, i.e. over a network as well as on media?. Exchanging Imaging Data. Agenda - PowerPoint PPT PresentationTRANSCRIPT
DICOM INTERNATIONALCONFERENCE & SEMINAR
Oct 9-11, 2010 Rio de Janeiro, Brazil
Exchanging Imaging Data
Cor Loef
Philips
Exchanging Imaging Data
• Objective: This presentation will answer the following question:– What are the types of DICOM objects and
how do we move them around, i.e. over a network as well as on media?
Exchanging Imaging Data
• Agenda– Main Classes of Objects:
Images, Presentation States, Structured Reports, Encapsulated Objects
– Pushing Objects, Pulling Objects, Finding Objects and Retrieving Objects
– DICOM: a Protocol vs a File Format vs a product Internal Data Representation
– Use of Media: CDs, Memory Sticks, Email, WADO
IE’s AttributesModules
Information Object Definition (IOD):
• DICOM Composite Objects:For persistent, “permanent” objects using
DIMSE-C commands (C-Store, C-Move, C-Find…)
Multiple IE’s: relate to DICOM Information Model (Patient-Study-Series-Image…)
Cannot be changed or modified, if so, create a new object with new SOP Instance UID
Information Object Definition (IOD):
Multi-frame Objects:
• Ultrasound Multiframe• Nuclear Medicine• XA and RF• New objects: MR, CT,
PET, XA-XRF (new), X-Ray 3D, US 3D
• VL and Ophthalmology• Any future new objects:
NM (new)
Vector
Structured Reports:
• Same structure as Images:– “main body” contains report and/or other
information (measurements, etc.) instead of pixels
– Same structure for header– Same study information– Modality is “SR”– Has a tree structure
SR example (IHE simple report):
0-n
CONTAINS
HAS OBS CONTEXT
1
CONTAINS
1-n
0-n
INFERRED FROM
Report Text (TEXT)
Image Reference (IMAGE)
Observation Context (See Figure 5.3-5)
1-n
Section Heading (CONTAINER)
Document Title (CONTAINER)
Image Reference (IMAGE)
Measurement (NUM)
0-n
Measurement (NUM)
0-n
HAS OBS CONTEXT
0-1
Observation Context (See Figure 5.3-5)
SR example (Key Image/Object Note KON):
Document Title(CONTAINER)
1 1-n
CONTAINS
HAS OBS CONTEXT
1
Image Reference(IMAGE)
Observation Context(See figure 5.3-5)
Key Image Description(TEXT)
Encapsulated Objects (SC and PDF):
• Some objects are difficult to encode as “native” objects:
• Secondary Capture (SC):– Digitized film, captured video,
scanned documents
• Encapsulated PDF:– typically for bone scans and eye care
(topographic maps)
- Present images (almost) identical on softcopy media in standard manner
- Separation of Stored Image Instances from Display characteristics and changes
- Includes shutters, image annotation, spatial transformation, display annotation
Softcopy Presentation State:
Solution:
- Create Composite object containing the presentation state parameters ONLY (no images)
- Link this Composite object to one or more images (Series, Images)
- Store within same Study; Modality “PR”
- Communicate with regular Storage service (C_Store); Retrieve with Query/Retrieve service
Softcopy Presentation State:
How do we move these objects around?
Pushing, Pulling Objects (Storage SOP Classes),
Finding Objects (Information model/FIND),
Retrieving Objects (Move/Get)
Modality
Information System
Display
Printer
Archive
PACS
Modality Push/PACS Push
DICOM C-Store
Storage Service class:
Transfer composite objects (e.g. images, reports, RT plans, waveforms) from one AE to another
One AE functions as the SCU, the other as SCP
SOP classes use C-Store DIMSE-C service
Information is stored in some medium, accessible for some time
Storage Service class:
(Issue! Might need Storage commitment!)
Modality
Information System
Display
Printer
Archive
PACS
Modality Pull/PACS Pull
DICOM C-Find
DICOM C-Move
SCU/SCP
Query/Retrieve Service class:
Simple Query, NOT full SQL:
Query: Basic image information query (“FIND”) using small set of common key attributes
Retrieve: Either from remote AE (“GET”), or Xfer from one AE to the other (“MOVE”)
Note: “GET” rarely supported
Extensions allow retrieval of selected frames of a multi-frame
Query/Retrieve Service class:
SQL
database
(Informix,
Sybase,
Oracle)
DICOM
I/F
Query/Retrieve Service class:
Note: Most vendors also support a proprietary,
direct protocol
Key Attributes:U: UniqueR: RequiredO: Optional
Pat name
Pat ID
----
----
----
Keys
Image IOD
Query/Retrieve Service class:
Keys for FIND:
Patient’s Name (0010,0010) R
Patient ID (0010,0020) U
Study Date (0008,0020) R
Study Time (0008,0030) R
Accession Number (0008,0050) R
Study ID (0020,0010) R
Study Instance UID (0020,000D) U
Modality (0008,0060) R
Series Number (0020,0011) R
Series Instance UID (0020,000E) U
Instance Number (0020,0013) R
SOP Instance UID (0008,0018) U
Q/R SOP Classes use:C-Find:
SCP matches all keys specified in the request against it’s database
May be at Patient, Study, Series or Image level
SCP provides Response for each match containing values for all keys and all requested, known attributes
Can Cancel if needed
Query/Retrieve Service Class:
Q/R SOP Classes use:C-Move:
SCU provides unique key values for needed SOP instances
SCP initiates C-Store(s) as SCU (on a separate Association)
SCP can issue C-Move responses with status pending until all C-Stores are completed or after each Store (see Conformance Statement)
Can issue Cancel at any time
Query/Retrieve Service Class:
Protocols, Files, Storage
• Protocols:– DICOM defines a standard communication protocol
(PDU, TCP/IP, addressing: port #, AE title)
• Files:– DICOM also defines a standard for files on media:
“Part-10 files” = meta information + a SOP instance– Media includes CD, DVD, Memory Sticks, etc.– Part-10 file format is also extended for zip files, email,
and web access (WADO)
DICOM Media:
Service Class Specifications
Information Objects Definitions
Data Set Structure and Encoding - Data Dictionary
Message Exchange File Format
Application Entity
DICOM Upper Layer Service Boundary DICOM Basic File Service Boundary
DICOM Upper Layer
Security Layer
(Optional)
TCP/IP Transport
Layer
Security Layer
(Optional)
Physical Media
and Media File Formats
Network Exchange On-Line Communication
Media Storage Interchange Off-Line Communication
Medical Information Application
• Meta-file header:• Transfer syntax (encoding)• SOP Class• Who generated it• Compliant with standard OS’s
• DICOMDIR required for exchange media
• Index/database of files
DICOM Media Specifications:
DICOM Application Entity
Service / Object PairsBasic Dir.
DICOM File Format
Media Formats: e.g. File data structures
Physical Media: e.g. CD-R; 90 mm MOD, etc.
Par
t 10
Par
t 11
Par
t 12
Protocols, Files, Storage:
• Device Internal Storage:– DICOM defines how images go in/out of device
– DICOM does NOT define how to archive images (there is NO archive standard)
– Some vendors keep images in DICOM format, some pre-process images using a compression method, either standard or proprietary
– Migration of both PACS databases and archives are common when changing releases, vendors, etc.
Conclusion:
• DICOM objects include:– not only images
– but also SR’s, Presentation States, and encapsulated objects
• DICOM images are moved around using:– the DICOM protocol
– the DICOM Part-10 file definition
• There is NO DICOM archiving standard, some archives store “natively”, some do not
DICOM INTERNATIONALCONFERENCE & SEMINAR
Oct 9-11, 2010 Rio de Janeiro, Brazil
Thank you!
Cor Loef:
www.philips.com