Picture Archive and Communication System PACS Based on

Picture Archive and Communication System: PACS Based on DICOM

The Parts of the DICOM Standard • Part 1 - Introduction and Overview • • Part 2 - Conformance Part 10: Media Storage and File Format for Media Interchange • Part 11: Media Storage Application Profiles • Part 3 - Information Object Definitions • • Part 4 - Service Class Definitions Part 12: Media Formats and Physical Media for Media Interchange Part 14: Grayscale Standard Display Function • Part 5 - Data Structures & Semantics • • • Part 6 - Data Element Listing and Typing Part 15: Security and System Management Profiles • Part 7 - Message Exchange Protocol • Part 16: Content Mapping Resource • Part 17: Explanatory Information • Part 8 - Network Support for Message • Part 18: Web Access to DICOM Persistent Objects (WADO) Exchange • Part 9 – Point to Point DICOM 3. 0 DICOM 2007 More than 100 supplements (extensions) to the Standard provide additional capabilities

DICOM History ► Based on ACR-NEMA standard ▪ ACR (American college of radiology) ▪ NEMA (National Electrical Manufacturers Association) • • • 1982 - ACR and NEMA form a joint committee 1985 - Publication of Version 1. 0 1988 - Compression and Mag Tape Standards 1988 - Publication of Version 2. 0 1989 - Began work on Network Version with HIS/RIS

DICOM History (cont. ) • The name was changed to separate the standard from the originating body • 1991 - Release of Parts 1 and 8 of DICOM • 1992 - RSNA demonstration, Part 8 • 1993 - DICOM Parts 1 -9 approved, RSNA demonstration of ALL parts • 1994 - Part 10: Media Storage and File Format • 1995 - Parts 11, 12, and 13 plus Supplements First successful DICOM Standard issued in 1993 DICOM is the ONLY standard in the world that covers the exchange of medical images

The DICOM File Format ► Header containing ▪ the patient's name / id ▪ type of media (CT, MRI, audio recording, etc. ) ▪ image dimensions. . . ▪ ► Body, containing «information objects» ▪ medical reports ▪ audio recordings ▪ images

A Typical DICOM Image File

DICOM Value Representations (VR) • All DICOM attributes are formatted according to 27 value representation (VR) types

Value Representation Description AE Application Entity OF Other Float AS Age String OW Other Word AT Attribute Tag PN Person Name CS Code String SH Short String DA Date SL Signed Long DS Decimal String SQ Sequence of Items DT Date/Time SS Signed Short FL Floating Point Single (4 bytes) ST Short Text FD Floating Point Double (8 bytes) TM Time IS Integer String UI Unique Identifier LO Long String UL Unsigned Long LT Long Text UN Unknown OB Other Byte US Unsigned Short UT Unlimited Text

DICOM Services • DICOM data attributes can be transmitted and processed between various DICOM devices and software (Applications) • DICOM applications provide services to each other • Particular services always associate with the data (IODs) that they process. • These associations are called Service-Object Pairs (SOPs)

Example: CT Storage SOP • • CT image = DICOM IOD (DICOM data object). CT Storage = DICOM Service CT Scanner = SCU (Service Class User) Digital Archive = SCP (Service Class Provider)

Data Communication • Information about each device is called Presentation Context. • Data transfer begins with Handshaking on the presentation context. • If the two applications can match their contexts, they can connect and start SCU-SCP processing.

DICOM Conformance Statement • Each DICOM unit will be accompanied by its own DICOM Conformance Statement from the manufacturer • This statement explains which SOPs (services) the unit supports, and to what extent (SCU, SCP, or both) • For example, if you buy a digital archive that supports only CT Storage SCU (does not support CT Storage SCP) you won’t be able to store CT images in it. The archive won’t be able to provide the CT storage service.

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