1、WADO Web Access to DICOM Persistent Objects,Emmanuel Cordonnier ETIAM,Partnerships,Cordonnier,DICOM 20th Anniversary Conference / WADO,page 2,Context,Users of medical information systems require rapid and reliable access to reports and images Within computerized environments such access is increasin
2、gly based on web technologies Access to relevant DICOM persistent objects is required without the need for duplication of such data objects Clinicians need to have access: either in native DICOM format for advanced use, or rendered into a generic format (e.g. JPEG, PDF) that can be presented with of
3、f-the-shelf applications,Cordonnier,DICOM 20th Anniversary Conference / WADO,page 3,ISO and DICOM effort,ISO TC215 (Medical Informatics) / WG2 (Messages and Communication) and DICOM / WG10 (Strategy Advisory) have decided to jointly develop a new standard for defining a web hook on DICOM After 2 yea
4、rs of work, a couple of face to face meetings and T-cons involving a douzen of key experts from user and vendor sides, WADO is ready for ballot,Cordonnier,DICOM 20th Anniversary Conference / WADO,page 4,Scope of the Standard,New web-based service for accessing and presenting DICOM persistent objects
5、 Simple mechanism for accessing a DICOM persistent object from HTML pages or XML documents, through HTTP/HTTPs protocol, using the DICOM UIDs (study, series, instance) NOT a way for searching DICOM images from the web, using parameters such as the Patient ID This standard relates only to DICOM persi
6、stent objects (e.g. images, reports, NOT workflow msg),Cordonnier,DICOM 20th Anniversary Conference / WADO,page 5,Normative references,DICOM PS 3.0 Digital Imaging and COmmunication in Medicine IETF RFC2045 to 2049 Multipurpose Internet Mail Extension (MIME) IETF RFC2396 Uniform Resource Identifiers
7、 (URI): Generic Syntax IETF RFC2616 Hypertext Transfer Protocol - HTTP/1.1 IETF RFC3240 Application/dicom MIME Sub-type,Cordonnier,DICOM 20th Anniversary Conference / WADO,page 6,Retrieving Persistent Objects,Objects,Cordonnier,DICOM 20th Anniversary Conference / WADO,page 7,Terms and definitions (1
8、),DICOM Persistent Object An instance of a data object as defined by DICOM PS 3.3 that has been allocated an unique identifier in the format specified for SOP Instance UID in DICOM PS 3.3 and has been chosen as an object to be saved securely for some period of time. Within the DICOM Standard, a DICO
9、M Persistent Object is referred to as a Composite Service Object Pair (SOP) Instance.,Cordonnier,DICOM 20th Anniversary Conference / WADO,page 8,Terms and definitions (2),Web Client System A system using Internet technologies (web, e-mail) interested in retrieving DICOM Persistent Objects from a Web
10、 Enabled DICOM Server, through HTTP/HTTPs protocol Web Enabled DICOM Server A system managing DICOM Persistent Objects and able to transmit them on request to the Web Client System Web Access to DICOM Persistent Objects Service enabling Web Client System to retrieve DICOM Persistent Objects managed
11、by Web Enabled DICOM Server, through HTTP/HTTPs protocol.,Cordonnier,DICOM 20th Anniversary Conference / WADO,page 9,Applications,Referencing an image or a report from an electronic patient record (EPR) Including references to images in an e-mail (second opinion, hospital to doctor distribution) Pro
12、viding access by outside referring doctors to a hospital web server that contains references to reports, images and waveforms Providing access to anonymized DICOM reports, images and waveforms via a web server, for teaching purposes and for clinical trials,Cordonnier,DICOM 20th Anniversary Conferenc
13、e / WADO,page 10,Scenario: form the reference,Image Manager & Archive,Report Repository,Acquisition Modality,Radiology dept,Clinical Documents Repository,Clinical dept,Interpretation,Cordonnier,DICOM 20th Anniversary Conference / WADO,page 11,Typical scenario: form the reference,The radiologist perf
14、orms an acquisition creating DICOM images He interprets the images producing a DICOM SR including reference to some significant images He exports the DICOM SR as an HL7 CDA including those references to external observations (instance, series and study UIDs as different id sets, and path of the DICO
15、M System in the reference ) The CDA is stored into the EMR/EPR/EHR database, using patient information for selecting the right record,Cordonnier,DICOM 20th Anniversary Conference / WADO,page 12,Scenario: web access,Image Manager & Archive,Report Repository,Acquisition Modality,Radiology dept,Clinica
16、l Documents Repository,Clinical dept,Interpretation,Clinical Document Consultation,Web Access to DICOM Persistent Object,Cordonnier,DICOM 20th Anniversary Conference / WADO,page 13,Typical scenario: web access,A clinician consults the CDA (the stylesheet builds the URI using the reference of the cus
17、todian which provided the CDA, completed by the Web Access to DICOM Persistent Objects parameters) The clinician clicks on one image link The WADO service, implemented as an HTTP script, build a DICOM FIND message using the parameters (studyUID=1.2.32.&seriesUID=1.2.32.), and retrieve the image form
18、 the DICOM server It creates the HTTP response body as a MIME part (either application/dicom, or image/jpeg),Cordonnier,DICOM 20th Anniversary Conference / WADO,page 14,Examples of implementation,DICOM Objects Database,DICOM Interface,Web Interface,DICOM Q/R,Web Access to Dicom Persistent Objects,DI
19、COM Objects Database,DICOM Interface,Web Gateway,DICOM Q/R,Web Access to Dicom Persistent Objects,Web Client System,Direct Interface,Gateway,Flexibility for the client to be implemented either as new systemor on existing system,Cordonnier,DICOM 20th Anniversary Conference / WADO,page 15,Interaction
20、Diagram,Web Enabled DICOM Server,Object(s) request (HTTP GET),Object(s) send (HTTP response header and body),Web Client System,Cordonnier,DICOM 20th Anniversary Conference / WADO,page 16,Syntax of the HTTP GET method,Syntax defined by the RFC2396 (URI) http:/? e.g: http:/www.hosp.fr/dicom/wado.asp?s
21、tudyUID=1The Web Access to DICOM Persistent Object standard defines only the ,Path of the Web Enabled DICOM Server,WADO Parameter(s),Cordonnier,DICOM 20th Anniversary Conference / WADO,page 17,Consistency with IHE IT Infrastructure Approach, Inspired by the WADO work, IHE IT Infrastructure has defin
22、ed a Retrieve Information for Display (RID) integration profile, enabling: To retieve a list of typed documents available for a patient (thanks to PatientID) To retrieve a document using its UID Inspired by the IHE IT Infrastructure work, WADO has defined a requestType(=WADO) parameter for compatibi
23、lity with extensions,Cordonnier,DICOM 20th Anniversary Conference / WADO,page 18,Selection Parameters,studyUID&seriesUID&objectUID &frameNumber studyUID = UID of the study containing the object(s) seriesUID = UID of the series containing the object(s) objectUID = UID of the single object (Service Ob
24、ject Pair SOP) frameNumber = number of the selected frame (multiframe image objects) if NOT retrieved as application/dicom,Cordonnier,DICOM 20th Anniversary Conference / WADO,page 19,MIME type of return object,The MIME type of the object contained in the contentType parameter, compatible the paramet
25、er of the GET method application/dicom for all objects, or a different MIME type for converting the DICOM object, depending of the nature of the object: image/jpeg for still image object text/html or text/plain for text object, or other optional formats,Cordonnier,DICOM 20th Anniversary Conference /
26、 WADO,page 20,MIME type of a Structured Report,application/dicom application/x-hl7-cda-level-one+xml for converting the SR into CDA (see HL7 Imaging SIG /DICOM WG20) text/plain for minimal version of document text/rtf for Word version of document application/pdf for stable version of document, poten
27、tially containing images text/html a priori without the images (to contained into only one file). The reference to the images can used the WADO syntax.,Cordonnier,DICOM 20th Anniversary Conference / WADO,page 21,Parameters when the object is return as application/dicom,transferSyntaxanonymizecharset
28、 transferSyntax = DICOM UID of the transferSyntax to be applied to the image (lossy/lossless compression). Implicit and Big Endian TS shall not be used. anonymize = “=yes” for blanking all the personal healthcare information (patient name, study date) as described in Sup. 55. Potentially the server
29、can refuse to deliver an object if there are some risk the personal information is burned into the image (secondary capture) charset = for converting the text fields in a different character set (available also if object return as text/xxx),Cordonnier,DICOM 20th Anniversary Conference / WADO,page 22
30、,Parameters when the object is return as image/xxx (1),imageQuality presentationUID & presentationSeriesUID |windowCenter & windowWidth imageQuality = controls the level of compression (from 1 to 100) presentation = UIDs of the Presentation State SOP and of its series to be applied on the image (P-v
31、alues, and display size set to the original size if undefined) windowCenter / windowWidth = controls the luminosity and the contrast of the B&W image,Cordonnier,DICOM 20th Anniversary Conference / WADO,page 23,Parameters when the object is return as image/xxx (2),regionrowscolumnsannotation region =
32、 part of the image to be displayed, in relative coordinates (top left hand corner and bottom right hand extent) rows = maximum number of pixels (vertical) columns = maximum number of pixels (horizontal) annotation = text to be superimposed of the image (“patient” and / or “technique” for demographic
33、 information and technical information, respectively),Cordonnier,DICOM 20th Anniversary Conference / WADO,page 24,Security aspects,It is clear that the information contained within DICOM objects may be considered as protected healthcare information (PHI). The protocol used, that is HTTP, can be repl
34、aced by HTTPs, which is its secure extension, for that purpose. Two optional parameters, anonymize and annotation, control respectively the absence of patient identification in a retrieved DICOM object and the presence of patient identification burned in to the pixel data of images.,Cordonnier,DICOM
35、 20th Anniversary Conference / WADO,page 25,Providing a image as image/xxx,Cordonnier,DICOM 20th Anniversary Conference / WADO,page 26,Client flexibility,The WADO functionality supports access to Native (un-rendered) DICOM data Associated rendering data e.g. Gray Scale Presentation State “Rendered”
36、information e.g. JPEG image So client design can be Simple, relying on basic features of the web browser Complex, providing advanced functionalities by taking raw DICOM data and deciding the processing and rendering to be applied,Cordonnier,DICOM 20th Anniversary Conference / WADO,page 27,Conclusion
37、,A small standard but a precious missing link offering the modernity of the Web to DICOM equipement and all the DICOM richness and stability to the (messy) Web Will be implemented largy soon in large and small systems ( where is WADO? ) To be extended (multiple objects retrieval, WSDL definition) after implementations Thanks to Hidenori Shinoda and Nick Brown for chairing the WADO ad hoc group, as well as to all the contributors of that group,
