Lo standard DICOM per le

immagini medicali

Stephane Chauvie

Santa Croce e Carle Hospital, Cuneo

Torino, 25 Maggio 2012

Sommario

Storia del DICOM

Rationale dello standard

Vocabolario DICOM

Esercizio pratico di utilizzo header DICOM

Da dove arriva il DICOM?

La genealogia:ACR (American College of Radiology)NEMA (Agfa, Boston Scientific, Camtronics, Carl Zeiss Meditec, Dejarnette, Dynamic Imaging, Eastman Kodak, ETIAM, Fuji, GE, Hologic, IBM, Konica, Matrixview, McKesson, MEDIS, Merge, Philips, RadPharm, R2, Sectra, Siemens, Sony, 3DHISTECH, Toshiba)

La cronologia:1983 primo comitato1985 primo standard pubblicato1988 standard 2.01993 standard 3.o (ultima rinnovata ogni anno ma sempre 3.0)

Cosa fa il DICOM?

…achieve compatibility and improve workflow efficiency…

5 aree funzionali:

Trasmissione e persistenza degli oggetti

Query and retrieve degli oggetti

Performance di tali azioni

Worflow management (worklist, storage commitment…)

Qualita’ e consistenza di un’immagine (display & print)

Cosa fa il DICOM?

Cosa fa

Definisce gli oggetti

CT, DX, NM, …

Definisce i servizi

Trasmissione, archiviazione, …

Cosa non fa

Non defiinisce l’architettura

ethernet, satellite, vpn, piccioni viaggiatori, …

Non definisce la funzionalita’

Flusso delle immagini, modalita’ di visualizzazione, …

Cosa e’ il linguaggio DICOM?

Oggetti (IOD) = Parole

Information Object Definition: ricette di quali ingredienti servono a definire un istanza di un oggetto:

Immagine CT, DX, MR,…

Basic film session

Scheduled procedure

Oggetti IOD

Gli attributi degli oggetti sono raggruppati in Moduli

Patient module

Name, ID, Birthdate…

Study module

Date and time, ID, Accession number…

Serie module

Date and time, ID, Number of images,

Image module

Pixel spacing, pixel location, slice thickness…

PS 3.5-2009 Section 7 The Data Set

Le lettere dell’alfabeto DICOM

Data Element Tag

An ordered pair of 16-bit unsigned integers representing the Group Number followed by Group Element

Value Representation (VR)

A two-byte character string containing the VR of the Data Element. The VR for a given Data Element Tag shall be as defined by the Data Dictionary as specified in PS 3.6. The two character VR shall be encoded using characters from the DICOM default character

Le lettere dell’alfabeto DICOM

Value Length (VR)

a 16 or 32-bit (dependent on VR and whether VR is explicit or implicit) unsigned integer containing the Explicit Length of the Value Field as the number of bytes (even) that make up the Value.

a 32-bit Length Field set to Undefined Length (FFFFFFFFH). Undefined Lengths may be used for Data Elements having the Value Representation (VR) Sequence of Items (SQ) and Unknown (UN).

Value Field

An even number of bytes containing the Value(s) of the Data Element. The data type of Value(s) stored in this field is specified by the Data Element's VR.

Transfer Syntax UID UI 1

Byte Ordering: Little vs Big Endian

Implicit Little Endian

1.2.840.10008.1.2 & 1.2.840.10008.1.2.1

Explicit Big Endian

1.2.840.10008.1.2.2

Explicit Little Endian

1.2.840..10008.1.2.1

Es. Implicit VR

//patient's name

groupN = 0x0010;

fwrite(&groupN,2,1,fileOut);

elementN = 0x0010;

fwrite(&elementN,2,1,fileOut);

strcpy(value,dcmObject->getPatient_name());

VL = strlen(value);

fwrite(&VL,4,1,fileOut);

fwrite(&value,VL,1,fileOut);

Command

Patient Name

Patient ID

Rows

Columns

Bits Stored

…

Network Transfer

Data Set=

+

Meta Data +Media Transfer

Data Set=

Group 0

( Describes Service: C-Store)

Group 2 ( Describes Data Set)

D I C O M [ . . . . . . . F I L E . . . . . . . . . . ]

D I C O M [ . . . . . M E S S A G E . . . . . . . ]

Header

Image

DICOM Transfer over Network & Media

File binario

File binario

File binario

File meta elements

Study information

Study information

Acquisition group

Relationship Group

Study information

La sintassi del DICOM

I verbi del linguaggio DICOM

I verbi sono i Services che specificano unI verbi sono i Services che specificano un’’azione da fare con e azione da fare con e sugli sugli oggetti sugli sugli oggetti ““ServiceService--objectobject--pairpair”” or SOPor SOP

Sono implementati in un client/serverSono implementati in un client/server

Service Class User eService Class User e’’ il servizio che usa il servizioil servizio che usa il servizio

Service Class Provider eService Class Provider e’’ il servizio che fornisce il servizioil servizio che fornisce il servizio

Esempio n.1: Stampa da una TAC. Print Esempio n.1: Stampa da una TAC. Print èè la SOP. La TAC ha la la SOP. La TAC ha la SCU e la stampante DICOM ha il SCPSCU e la stampante DICOM ha il SCP

Esempio n.2: Send di esame da DX a Workstation. CT storage Esempio n.2: Send di esame da DX a Workstation. CT storage èè la la SOP. La TAC ha la SCU e la workstation ha il SCP. Da conf: SOP. La TAC ha la SCU e la workstation ha il SCP. Da conf: TCP/IP address, Port number e AE title.TCP/IP address, Port number e AE title.

ServiziServizi

DICOM verification: pingDICOM verification: ping

DICOM storageDICOM storage

Storage commitmentStorage commitment

PrintPrint

Query/retrieveQuery/retrieve

26

Comunicare con il DICOM

ID: CT_AE1

IP: 10.3.253.8

Port: 104

ID: WK_AE1

IP: 10.3.253.9

Port: 4006

IP Addr AE Title Port #

10.3.253.1 Fusion 104

10.3.253.9 WK_AE1 4006

IP Addr AE Title Port #

10.3.253.1 Fusion 104

10.3.253.8 CT_AE1 104

Association / Association /

NegotiationNegotiation

CT Config FileCT Config File Wkstn Config FileWkstn Config File

Node Level Node Level

SecuritySecurity

Typical Network FlowDICOM AE DICOM AE ““AA”” DICOM AE DICOM AE ““BB””AA--ASSOCIATEASSOCIATE--RQRQ

AA--ASSOCIATEASSOCIATE--ACAC

AA--RELEASERELEASE--RSPRSP

AA--RELEASERELEASE--RQRQ

oror

AA--ASSOCIATEASSOCIATE--RJRJ

DICOM MessagesDICOM Messages

oror

AA--ABORTABORT

Either AEEither AE

Handshake Requirements

DICOM Network RolesSuccessful communication - products must play “opposite roles”

Receive images = Service Class Provider (SCP)

Send images = Service Class User (SCU)

Network roles are defined for all DICOM Network roles are defined for all DICOM Network roles are defined for all DICOM Network roles are defined for all DICOM FunctionsFunctionsFunctionsFunctions

Network roles are defined for all DICOM Network roles are defined for all DICOM Network roles are defined for all DICOM Network roles are defined for all DICOM Network roles are defined for all DICOM Network roles are defined for all DICOM Network roles are defined for all DICOM Network roles are defined for all DICOM FunctionsFunctionsFunctionsFunctionsFunctionsFunctionsFunctionsFunctions

Image SendImage SendImage Send

CT Image StorageSOP Class (SCU)CT Image StorageCT Image StorageSOP Class (SCU)SOP Class (SCU)

CT Image StorageSOP Class (SCP)CT Image StorageCT Image StorageSOP Class (SCP)SOP Class (SCP)

DICOM Conformance Statement

It is Required!

It is a Public Document

It Conveys a Product’s DICOM Functionality

It is Based on DICOM Vocabulary

Abstract Syntaxes (SOP Classes), Transfer Syntaxes, SCU/SCP…..

It is Used to Compare Connectivity

It is most Often on the Web @ Vendor Site

It Does Not Address All of an Application’s Capabilities, but should Address All of the Application’s DICOM ones

Ok, you say its DICOM, Ok, you say its DICOM,

prove it!prove it!

A Major Step Towards InteroperabilityA Major Step Towards Interoperability

Grazie per l’attenzione

DICOM WG-28 Physics

1° riunione nel Febbraio 2012

DICOM Standards Committee:

Co-chairs: Donald Peck, AAPM & Annalisa Trianni, EFOMP

Secretariat: Lynne Fairobent, AAPM & Alberto Torresin, EFOMP

Scopi:

Correction Proposal (CP)

Includere dati “da fisici medici”