The suitability of XDS-I for national sharing in the NHS in England

Transcription

1 The suitability of XDS-I for atioal sharig i the NHS i Eglad Movig to a XDS-I architecture to support image ad report sharig across the LSP-provided PACS ad RIS estate i Eglad is techically possible but, cosiderig the techology s curret level of maturity, would require sigificat developmet ad fudig. NHS Coectig for Health believes a pragmatic approach is required, moitorig the progress of ay XDS-I implemetatios i Eglad ad the developmet of the XDS-I stadard, ad supportig ad ifluecig these where appropriate, but i the meatime cotiuig to make available solutios which meet the majority of cliicias image sharig requiremets ow.

2 Page 2 Backgroud This paper presets a summary of work completed by, ad o behalf of, NHS Coectig For Health (NHS CFH) over the last ie moths to assess the feasibility of usig IHE 1 XDS-I 2 based solutios to eable the atioal sharig of diagostic images ad reports. This work was udertake as a output of a NHS CFH ad Royal College of Radiologists workig group ad focused o determiig the aswers to three fudametal questios: Does the atioal Spie ifrastructure ad some of the icumbet applicatios associated with it provide a suitable platform for a IHE XDS registry ad repository 3? Do the PACS ad RIS products implemeted by our Local Service Providers (LSPs) have the ecessary iteroperability capabilities to act as providers ad cosumers to a Spie-based Registry ad thus participate i a XDS-I based atioal sharig solutio? What is the capability ad maturity of the XDS-I profile ad how suitable is it for a implemetatio o the scale of the NHS i Eglad? The study ivolved egagemet with a wide rage of stakeholders icludig IHE, idustry ad cliical represetatives. Its coclusios were formed followig extesive desk-based aalysis, stakeholder iterviews ad presetatio ad discussio of fidigs at a umber of forums. This paper presets a summary of work completed by, ad o behalf of, NHS Coectig For Health (NHS CFH) over the last ie moths to assess the feasibility of usig IHE XDS-I based solutios to eable the atioal sharig of diagostic images ad reports 1 IHE (Itegratig the Healthcare Eterprise) is a iitiative by healthcare professioals ad idustry to improve the way computer systems i healthcare share iformatio. IHE promotes the coordiated use of established stadards such as DICOM ad HL7 by ecapsulatig them i Profiles to address specific cliical eeds i support of optimal patiet care ( 2 Cross-Eterprise Documet Sharig for Imagig (XDS-I) is a IHE profile dedicated to sharig diagostic imagig. 3 A Spie-based registry/repository would form part of a atioal sharig solutio, providig a atioal idex ad storage facility for reports ad poiters to the correspodig images. The suitability of XDS-I for atioal sharig i the NHS i Eglad

3 Page 3 XDS-I defiitio The XDS profile allows participat systems to exchage cliical documets. To that extet it works i a maer similar to a documet maagemet system. The profile uses a documet registry for the capture of metadata about a documet, icludig a poiter to the locatio of the documet i a repository. The subject of this ivestigatio was XDS for Imagig (XDS-I). XDS-I builds o the XDS stadard by allowig images - typically DICOM images - to be located ad retrieved remotely. The overall result is the a three stage process for retrieval of images: 1. Locate documets/reports for a patiet i the registry. 2. Retrieve the documet/report from the repository. 3. Follow a referece from the documet/report to the image source ad retrieve the image(s). XDS ad XDS-I referece a umber of logical actors that are able to sed ad receive specified trasactios. The focus of the ivestigatios was to assess the relative suitability of Spie ad LSP-provided PACS ad RIS applicatios i Eglad for playig these actors, takig particular ote of the maturity of the stadard ad evidece of scalability. Figure 1 summarises the XDS-I.b actors ad where they might logically reside. Cetral Systems LSP Systems Documet Source Imagig Documet Source Patiet Idetity Feed [ITI-8] Patiet Idetity Feed [ITI-44] Provide & Register Imagagig Documet Set MTOM/XOP [ITI-68] Register Documet Set-b [ITI-42] Patiet idetity source Documet Registry (XDS.b) Documet Repository (XDS.b) Registry Stored Query [ITI-18] LSP Systems Documet Cosumer (XDS.b) Imagig Documet Cosumer Retrieve Documet Set [ITI-43] WADO Retrieve [RAD-55] Retrieve Imagig Documet Set [RAD-69] Retrieve Images [RAD-16] Retrieve Presetatio States [RAD-17] Retrieve Reports [RAD-27] Retrieve Key Image Note [RAD-31] Retrieve Evidece Documets [RAD-45] Figure 1 XDS-I.b actors ad trasactios. The suitability of XDS-I for atioal sharig i the NHS i Eglad

4 Page 4 XDS-I s suitability for atioal sharig I assessig XDS-I s suitability we ca draw from the coclusios of a atioal feasibility study relatig to the Spie. May of the fidigs i this documet were ot Spie-specific but rather geeral coclusios that apply to atioal scale implemetatios of XDS-I. This study summarised a mix of techical ad professioal fidigs: IHE profiles (XDS, XDS-I) do describe much of the framework required to create atioal sharig solutios. IHE leaves a umber of sigificat aspects of ay solutio up to the particular implemetatio to defie. This meas that large parts of a atioal solutio would eed to be specified ad built, icludig: Security Repository documet sematics Affiity domai/iformatio Goverace (IG) policies/nhs Care Record Guaratee Versio ad cofiguratio maagemet A umber of gaps i a atioal solutio would be covered by profiles that have oly recetly bee proposed by IHE. These will take a umber of years before they reach a maturity suitable for a atioal solutio: Edpoit resolutio Image trasfer stadards suitable for a large implemetatios Notificatio mechaisms Spie compoets will provide a head start for some of the IHE actors ad are likely to cost a similar amout to buildig a product from scratch. Aspects that the atioal solutio already provides to a greater or lesser extet are: Security Edpoit resolutio Iformatio goverace policies A atioal sharig solutio would preset challeges of scale that o curret IHE-based solutios address today. The suitability of XDS-I for atioal sharig i the NHS i Eglad

5 Page 5 XDS-I ad the PACS ad RIS estate i Eglad There is curretly little evidece of available XDS-I cotet from the LSP-supplied products deployed i the majority of acute trusts i Eglad. Oly oe out of the three LSPs supplyig PACS has bee opely spedig time lookig at XDS-based solutios ad how they might be icorporated ito loger term developmet ad deploymet strategies. Although it has ot bee possible to get a detailed baselie positio of the Eglish PACS ad RIS estate durig the course of our ivestigatios, we ca see from publicly available iformatio that there is a sigificat amout of developmet work required, icludig support for the NHS Number, to support the XDS ad associated profiles as defied by IHE, as well as the additioal implemetatio cosideratios. The challeges of implemetig XDS-I across acute trusts i the NHS i Eglad Although our study showed that XDS-I could be implemeted withi the Spie ad with the willigess of PACS ad RIS suppliers, it would take time as the stadard is ot yet prove o the scale of NHS i Eglad. A umber of challeges are worth otig, may of which ca be overcome with the ecessary fudig ad time (although further developmet would require a very robust busiess case clearly outliig costs ad beefits): A atioal XDS-I implemetatio would require a sigle affiity domai which defied the characteristics of the sharig commuity. It would require a cosistet patiet idetity scheme which, i the case of acute trusts i Eglad, would eed to be the NHS Number. The affiity domai demads a cosistet approach to security ad audit ad it is recommeded that restrictios o agreed IHE profiles (kow as a specificity, i IHE parlace) should be published i a exteral iterface specificatio. There would also eed to be agreemet o documet sematics across the domai, i.e. all aspects of documet amig ad cotet would eed to be agreed at a atioal level. There are a umber of gaps albeit itetioal oes - i the IHE profiles where implemeters are required to devise their ow solutios. I particular, the eed to resolve edpoits both for repositories ad image providers was idetified. This would itroduce the eed for a directory service that would register ad maage edpoit defiitios so they could be trasformed ito the required physical iteret addresses. The suitability of XDS-I for atioal sharig i the NHS i Eglad

6 Page 6 The challeges of implemetig XDS-I across acute trusts i the NHS i Eglad (cotiued) A poit-to-poit iterface - relyig o a Public Key Ifrastructure (PKI) 4 for security is the recommeded optio for the trasfer of image files across boudaries. PKI is somethig ot curretly implemeted across the NHS ad would be expesive item. I additio to supportig the required XDS actors ad trasactios, the XDS-I profile specifies additioal trasactios for the purpose of trasportig the imagig files located usig the stadard XDS actors. For image trasfer, the curret HTTP-based WADO trasactio should be used i the short term, later movig to a web services-based trasactio implemetatio, versios of which are curretly uder developmet. This is because the curret WADO trasfer is ot suitable for large scale implemetatios, while WADO for web services is expected to provide better support. As well as supportig the XDS ad XDS-I profiles, a successful atioal solutio would also eed to support suitable autheticatio ad authorisatio techiques. Curret approaches to autheticatio ad message security 5 would eed to be maitaied or where ecessary freshly implemeted as the recommeded profiles for IHE (EUA) are ot suitable for the curret atioal ifrastructure. The level of choice, particularly with regards to RIS, available to acute trusts i Eglad would challege the roll-out of a atioal solutio as all RISs would have to be compliat to the sigle affiity domai specificity before atioal sharig could become effective. This is likely to remai a feature of the atioal ladscape ad will eed to be addressed by the RIS suppliers so that they achieve compliace to XDS should the atioal registry be required. As well as supportig the XDS ad XDS-I profiles, a successful atioal solutio would also eed to support suitable autheticatio ad authorisatio techiques 4 Public Key Ifrastructure - a framework for creatig ad maagig a secure method for exchagig iformatio based o public key cryptography across a o-secure etwork. 5 This would iclude the smart card-based IDM ifrastructure ad the TLS-based mutual autheticatio of messages. The suitability of XDS-I for atioal sharig i the NHS i Eglad

7 Page 7 Directio of travel Movig to a XDS-I architecture to support image ad report sharig across the LSP-provided PACS ad RIS estate i Eglad is techically possible but, cosiderig the techology s curret level of maturity, would require sigificat developmet ad fudig. We have leared that while IHE has goe a log way towards eablig system iteroperability through its defiitio of the XDS profiles, the XDS-I profile is still maturig ad there are a umber of importat features (the XDS-I.b ehacemets) that are still i trial implemetatio. NHS CFH as a active participat i IHE, ad workig with the Royal College of Radiologists ad other stakeholders, will track ad seek to ifluece a umber of profiles relevat to a atioal sharig solutio as metioed i this paper 6. Additioally, further profiles ad additioal trasactios which we believe will be required (e.g. cofiguratio maagemet ad the improved security capabilities of the WADO for web services trasactio) are still beig defied. Furthermore, there is a sigificat amout of additioal implemetatio guidace which eeds to be defied i support of a atioal sharig affiity domai. May of the challeges are drive by the scale of the LSP PACS ad RIS deploymets across Eglad: as of today, XDS-I has oly bee deployed at small scale, i o way comparable to that of the NHS i Eglad. Based o these fidigs, NHS CFH plas to moitor ad ifluece the progress of ay XDS-I implemetatios i Eglad ad the XDS-I stadard, give that techology chages costatly, ad to support small-scale pilots where these are desired by groups of acute trusts ad/or strategic health authorities (SHAs). I parallel with this, NHS CFH, workig with SHAs ad trusts, will cotiue to deploy image ad report sharig techology that works ad is affordable today, ad which already meets may of the requiremets imagig ad other healthcare professioals have of image sharig. This approach implictly ackowledges that such solutios may fall short of the full potetial offered by a mature XDS-I solutio. However, the busiess beefits of the latter would eed to be robust ad clearly defied i order to secure the level of ivestmet that would be required at this stage. Should resources allow, providig implemetatio guidace ad ecouragig its use would be a useful step i supportig smaller XDS or XDS-I implemetatios at a trust or care commuity level, easig the trasformatio to a atioal affiity domai at some future date whe the frameworks have matured ad a clear beefits case exists. Further iformatio If you have ay queries about this paper please the atioal PACS programme at pacs.query@hs.et 6 For example WADO for Web Services, SDDS (for edpoit resolutio) ad DSUB (Documet - meta-data - Subscriptio). The suitability of XDS-I for atioal sharig i the NHS i Eglad

8 Page 8 Glossary Actor Affiity domai DICOM Domai Edpoit resolutio EUA HTTP IHE IHE profiles Local Service Provider (LSP) A actor i this cotext is ay of the fuctioal etities (for example the registry or repository) defied withi a IHE profile that trasacts with other fuctioal etities withi that IHE profile. The affiity domai defies the scope of a XDS sharig commuity. A affiity domai always has oe Registry ad it defies a set of rules ad policies that gover how the members of the affiity domai participate i sharig withi that commuity. Digital Imagig ad Commuicatios i Medicie (DICOM) is a stadard for file format defiitio ad a etwork commuicatios protocol for the hadlig, storig, pritig, ad trasmittig of diagostic imagig. Delieates the scope of a area of iterest which i this cotext refers to the affiity domai. A method by which logical addresses qualifyig the locatio of a XDS repository or ay image store (such as a PACS) are traslated ito physical web addresses that eables the locatio ad retrieval of documets ad images. Eterprise User Autheticatio (EUA) is a IHE profile that defies a sigle user registratio ad autheticatio scheme across a affiity domai eablig all participatig systems to be accessed usig the same user ID. Hypertext Trasfer Protocol (HTTP) is the stadard protocol that defies how messages are formatted ad set over the iteret. Itegratig the Healthcare Eterprise a ot-for-profit orgaisatio set up by the healthcare idustry to promote the iteroperability of healthcare systems by the defiitio of frameworks that simplify ad costrai existig stadards to ease their implemetatio. A IHE Profile defies a area of focus for iteroperability defiitio by prescribig a set of actors with their associated trasactios which eable a related set of fuctios to be performed (e.g. XDS). A Local Service Provider, as part of the Natioal Programme for IT is resposible for delivery of services at a local (Trust) level ad supportig local orgaisatios i deliverig the beefits from these services. They esure the itegratio of existig local systems ad, where ecessary, implemet ew systems to eable atioal applicatios to be delivered locally. The suitability of XDS-I for atioal sharig i the NHS i Eglad

9 Page 9 Glossary (cotiued) NHS Care Record Guaratee NHS Coectig for Health NHS Number Notificatio mechaisms PACS Public Key Ifrastructure (PKI) Registry Repository RIS The NHS Care Record Guaratee for Eglad sets out the rules that gover how patiet iformatio is used i the NHS ad what cotrol the patiet ca have over this. It covers people's access to their ow records, cotrols o others' access, how access will be moitored ad policed, optios people have to further limit access, access i a emergecy, ad what happes whe someoe caot make decisios for themselves. NHS Coectig for Health supports the NHS i providig better, safer care, by deliverig computer systems ad services that improve how patiet iformatio is stored ad accessed. The NHS Number is the atioally uique patiet idetifier, used to help healthcare staff ad service providers match patiets to their health records. Everyoe registered with the NHS i Eglad (ad Wales) has their ow NHS Number allocated at birth. Notificatio mechaisms are automated procedures that otify iterested parties that iformatio previously received (or viewed) from a exteral orgaisatio as part of, for example, a XDS or XDS-I trasactio has bee updated. Picture Archivig ad Commuicatios System (PACS) is a computer system that maages the short ad log-term storage, retrieval ad presetatio of diagostic images. A framework for creatig ad maagig a secure method for exchagig iformatio across a o-secure etwork based o usig key pairs to ecrypt ad decrypt data. The registry i the cotext of the XDS profile holds a idex of the meta data cataloguig documets held i the repository. The idex is queried by users i order to idetify documets they wish to retrieve. A repository i the cotext of the XDS profile holds documets made available for sharig by those participatig i a XDS affiity domai. There may be more tha oe repository associated with the sigle affiity domai registry. Radiology Iformatio System (RIS) is a computer system used by hospital radiology departmets to store, maipulate ad distribute patiet radiological data ad imagery. The system geerally cosists of patiet trackig ad schedulig, result reportig, workflow maagemet ad trackig the images stored o a PACS. The suitability of XDS-I for atioal sharig i the NHS i Eglad

10 Page 10 Glossary (cotiued) WADO Wado for web services XDS XDS-I Web Access to DICOM persistet objects is a stadard by which ative DICOM objects or redered DICOM objects (i.e. coverted to a more readable format such as PDF or JPEG) are retrieved usig the stadard web HTTP/HTTPs (secure) protocol. WADO for web services is a further developmet of WADO that wraps a additioal stadard object layer aroud the trasactio which simplifies ad improves, amogst other thigs, the security ad reliability features. Cross-eterprise Documet Sharig (XDS) a IHE profile dedicated to simplifyig the sharig of documets across eterprises by providig a stadards based iteroperability framework focused aroud the use of a documet registry ad repository. Cross-eterprise Documet Sharig for Imagig (XDS-I) a IHE profile which is a developmet of the XDS profile usig the same registry ad repository capability to locate ad retrieve diagostic images. The suitability of XDS-I for atioal sharig i the NHS i Eglad

11 This documet is prited o paper made from recycled fibre ad fibre from sustaiably maaged forests. Crow Copyright 2010 Ref: 4692