Kingston University London

Transcription

1 Kingston University London «INFORMATION TECHNOLOGY IN MEDICINE. A STRUCTURE ANALYSIS OF A PICTURE ARCHIVE COMMUNICATION SYSTEM (P.A.C.S) AND A TOP DOWN DESCRIPTION OF SUCH A SYSTEM IN A HELLENIC UNIVERSITY HOSPITAL» KONSTANTINOS V. MESSADOS Master of Science in Networking and Data Communications THESIS

2 Kingston University London «INFORMATION TECHNOLOGY IN MEDICINE. A STRUCTURE ANALYSIS OF A PICTURE ARCHIVE COMMUNICATION SYSTEM (P.A.C.S) AND A TOP DOWN DESCRIPTION OF SUCH A SYSTEM IN A HELLENIC UNIVERSITY HOSPITAL» Dissertation submitted for the Degree of Master of Science in Networking and Data Communications By KONSTANTINOS V. MESSADOS SUPERVISOR SOTIRIOS MANIATIS KINGSTON UNIVERSITY, FACULTY OF COMPUTING, INFORMATION SYSTEMS & MATHEMATICS ΤEI OF PIRAEUS, DEPARTMENTS OF ELECTRONICS AND AUTOMATION JULY

3 Contents 1. Introduction Introduction What is PACS PACS Design Concept PACS Infrastructure Design Picture Archiving and Communication System Anatomy PACS Architectures Stand-Alone PACS Model Client/Server Model Web-Based Model PACS Contributors Modalities Hospital Information System (HIS) Radiology Information System (RIS) PACS Components Database Server (DBS) Network Gateway - Workflow Manager (WFM) Archive Server (AS) Applications Server (APS) Curator Clients PACS Workflow PACS /HIS/ RIS Work Flow PACS and Tele-Radiology Clear Teleradiology Model PACS and Teleradiology Combined Model PACS Communication Protocols Industrial Standards (HL7 and DICOM) and Work Flow Protocols (IHE) The Health Level 7 Standard Health Level

4 4.1.2 New Trend in HL The Dicom 3.0 Standard History DICOM Standard DICOM Data Format The General DICOM Communication model IHE (Integrating the Healthcate Enterprise) What is IHE? PACS Installation in University Hospital of Ioannina The Hospital Radiology Department Equipment Magnetic Resonance Imaging Modalities (MRI) Computed Tomography Modalities (CT) Nuclear Medicine Modalities Radiography Modalities Mammography Modalities Ultrasound Modalities Radiology Department Workload and Workflow before PACS Radiology Department Workload Radiology Department Workflow before PACS Needs and demands of the Hospital before PACS installation PACS Installation and Integration Hardware and Software Installation System Integration Radiology Department Workflow through PACS PACS Benefits General PACS Benefits PACS benefits in University Hospital of Ioannina Cost Benefits Film Operation Costs Space Costs Personnel Costs.50 3

5 Cost-Benefit Analysis 50 6 P.A.C.S Risks P.A.C.S. Network Infrastructure Risks Hardware Dysfunction Communication Problems Unauthorized Access Risk Analysis Assets Value Estimation Threat Level Estimation and Asset s Vulnerabilities Risk Level Estimation for each asset Threats Level Summary PACS Protection User Authentication Passwords One-time passwords Public-key cryptography Zero-knowledge proofs Digital Signatures Firewall Packet filtering firewall Stateful firewall Deep packet inspection firewall Application-aware firewall Application proxy firewall Building s Infrastructure Conclusion...70 References 72 4

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7 1. Introduction 1.1 Introduction During the past 10 years, PACS (Picture Archiving and Communication System) based on digital, communication, display, and information technologies (IT) has turned over the practice of radiology and, in a way, of medicine. This thesis presents the anatomy of a picture archiving and communication system, some PACS-based functions, the applications and the connectivity protocols. Moreover, this thesis presents the installation of that kind of system, in University Hospital of Ioannina- Greece and through this installation there are presented all the advantages and disadvantages that PACS have in real conditions Many advantages arise of introducing digital, communications, display and IT to the typical paper- and film-based operation in radiology and medicine. For example the modality diagnostic value can be improved through digital imaging plate and detector technology and various energy source digital imaging modalities and also at the same time the patient not to exposure in high radiation. Furthermore a digital image for value-added diagnosis can be manipulated through the computer and display. Also, digital, communication, and IT technologies are serviceably to understand the health care delivery workflow resulting in increasing the speed of the health care services and decreasing the needed cost. Including all these advantages, the digital communication, and IT technologies have definitely change the process of many healthcare services like acquiring, diagnose,archiving, and delivering medical images and generally have change all the management of medical information in industry of health care. (Reference No.13) One natural development along this line is the emergence of digital radiology departments and the digital health care delivery environment. The digital radiology department contains two main components: the Hospital information system (HIS) that contains the radiology information system (RIS) and a digital imaging system. Hospital Information system (HIS) is the system that manages the demographic data of each patient and through RIS it is making the delivery of the appropriate data to the digital imaging department. (Reference No.4) 6

8 The digital imaging system is known as picture archiving and communication system (PACS). PACS refers to a computer system that is used to capture, store, distribute, and then display medical images. Electronic images and reports are transmitted digitally via PACS. This eliminates the need to manually file, retrieve or transport film jackets. PACS attempts to overcome the limitations of film-based systems by providing economical storage, rapid retrieval of individual images, access to images acquired with multiple modalities, and simultaneous access to the same image at multiple sites (Reference No.10) The purpose of this thesis is to present PACS. It will present the anatomy of this system, the way that this system integrates with HIS and RIS and it s main components Continuously there will be presented the connectivity protocols of PACS-HIS RIS integration and finally there will be presented the installation of that kind of system in University Hospital of Ioannina. 1.2 What is PACS PACS Design Concept The communication system and the picture archiving comprise of image and data acquirement, storage, and display subsystems completed by digital networks and application software. It is so simple such a film digitizer connected to a display workstation with a small image database or as complex as an enterprise image management system. The birth of PACS estimated in the late 1980s, created mainly on an ad hoc basis, helping small subsets, called modules, of the total operation of a radiology department. (Reference No.14) Each of these PACS subsets operate as an isolated unit unable to communicate with other subsets. Although the PACS concept has been established to work sufficiently for each of the different radiology and clinical services, the confusion of connectivity and cooperation between subsets have not been addressed. This problem exists since more PACS subsets were added to hospital networks. Maintenance, routing decisions, coordination of machines, fault tolerance, and expandability of the system became increasingly difficult problems. The inconvenience of the first PACS design had one main reason. The deficiency 7

9 of knowing the complexity of a wide system and the unavailability at that time of many important, for PACS, technologies. A PACS system as is know understood should emphasize to system connectivity and integration. A wide and general multimedia data management system that is easily extendable, flexible, and versatile in its operation calls for both top-down management to integrate various hospital information systems and a bottom-up engineering approach to build a foundation (Reference No.9) From the management point of view, hospital wide or enterprise PACS system are very attractive to administrators and financial managers as it provides clear economic results that warrant its existence. Hospitals that work in a PACS environment save huge amounts of money only from making their workflow film less. As a result many hospital managers have try to find ways to expand this cost saving ratio out of the radiology department and so to extend PACS in all hospital. From the engineering point of view, the PACS substructure confirms that PACS comprises features as standardization, open architecture, expandability for future growth, connectivity, reliability, fault tolerance, and cost-effectiveness (Reference No.10) PACS Infrastructure Design PACS substructure provides the appropriate network manufacture for integration through many different image acquisition modalities and gives the opportunity for a intelligent management of all patients demographic or in general patient-related data. Furthermore, it gives an effective an safe way of viewing, analyzing, and substantiating exam results and creates new methods of effectively confiscate diagnosis or study results to referring physicians and radiographers. PACS system base on hardware components (imaging device interfaces, storage devices, host computers, communication networks, display systems) accomplished by a standard, flexible software system that offers communication, database management, storage management, job scheduling, inter processor communication, error handling, and network monitoring. The substructure of PACS makes able to perform not only the basic control functions but also, more complex research, clinical service, and education requests. 8

10 The software components of PACS system provide the substructure of all the system to work as a system instead and not as separate networked computers. Patient data servers, imaging modalities, data/modality interfaces, PACS controllers with database and archive, and display workstations are all hardware components, that manage the ata/image flow in PACS, through their connection in communication networks. Images and data that are archived in PACS can be delivered from archive servers to application server and clients form many reasons Figure describes the main PACS components and the workflow of data Figure Generic PACS Components Workflow(Reference No 16) 2. Picture Archiving and Communication System Anatomy This paragraph discusses the anatomy of a picture archiving and communication system (PACS). The first topic is the basic components that work nearby a PACS system. They are the systems that produce the medical images and the systems that complete all the healthcare information system by adding on the images demographic and billing data.continuously there are presented al the components of a picture archiving and communication system. (Reference No.3) 9

11 PACS is comprised of several elements: database and file server, an archive server and system, an application server, a network gateway, a curator and the clients. The sum of these components is called cluster. Figure 2. PACS Cluster A typical configuration has a Database Server, one or more Archive Servers and one or more Network Gateways. Local Clients are spread throughout the entire network, as well as Remote Clients outside the enterprise firewall. These connect to one or more Application Server machines, which act much like a proxy machine to handle security, authentication, and communication with PACS Server components. When images are transmitted to the cluster, the Network Gateway performs validation of the study images and data. Validation requires the Network Gateway to query the HIS/RIS and ensure that the study and patient demographics match what is currently incoming from a modality or a transmit device. If the validation is successful, the studies are "allowed" into the system and the study meta-data are sent to the Database Server. The Database Server collects and manages all patient and study demographic data. The Database Server forwards the study images to the Archive Server, where the images are saved in local cache until they are permanently stored in the DICOM archive. A PACS Client, both Local and Remote, is used to view study images. Clients can connect to a local cache, or to a web cache of compressed images generated by the Curator. When a study is diagnosed and dictated, the status of the 10

12 study is updated at the Database Server, and when a report is generated, it is forwarded to the HIS/RIS. (Reference No.3) 2.1 PACS Architectures In nowadays there are three base PACS architectures: 1) Stand-alone, 2) Client-server, and 3) The Web-based Stand-Alone PACS Model The stand-alone model has three major characteristics: (1) The Archive Server automatically sends the exams to the predetermined diagnostic station (2) The Diagnostic Stations have also the ability to query and retrieve images and exam data in general from the archive server. (3) The Diagnostic Stations can store for short-term the exams topically. (Reference No.7) Figure Stand-alone architecture general data flow. (Reference No.7) The main characteristics are that images are sent from PACS (2) to the diagnostic stations automatically (one way arrows, 3,4 ). Furthermore, the workstations with cache storage can query and retrieve images (dual way arrows 5,6). The data work flow of a stand-alone PACS model is shown in Figure In details: 1. The modality sends the images to the PACS Archive Server. 2. PACS Archive Server stores the exam. 11

13 3. The Archive Server automatically, sends copies of the images to any user of diagnostic station queries them, in order to make a diagnosis, reading or review. 4. Older exams are recalled from the Archive server and automatically a copy of them is sent to the workstations. The previous process can also be done and manually. 5. Every end-user workstation can store locally a specific amount of exams. Advantages: (1) System flexibility as if the main server crashes down, the modalities can send the images directly to the workstations and so the radiologists continue working (2) It is safer for the data, such many copies of them are divided through the workstations an so there is less risk of loosing data. (3) The workstations have their own storage cache and so they can store exams topically. (4) Before the archiving, there can be made the exam changes to the DICOM header for quality control Disadvantages: (1) The way that the workstations will work depends on the correct exam distribution which is not possible every time. (2) As the exams are sent to concrete workstations, it is possible, every workstation to have a different exam work list, fact that makes the exam reading at any workstation in one setting, very difficult. (3) Query/retrieve function can be very complex. (4) It is very possible different radiologists to read the same examination in different workstations in the same time (Reference No.7) Client/Server Model The client/server model has three major characteristics: (1) PACS server archives centrally all the images (2) Through a client workstation and from one worklist the end user can selects an exam from the archive server. (3) Client workstations can not store exams topically and so all images are flushed after reading. (Reference No.7) The data work flow of the client/server PACS model is shown in Figure

14 Figure 2.1.2Client/server architecture general data flow. (Reference No.7) The main characteristics are that images are centrally archived in the PACS server, the workstations query images from the PACS server through a worklist, the workstations can not store exams topically and all images are flushed after reading. In details: 1. The imaging modality sends the images from a completed examination to PACS archive server. 2. PACS archive server stores the examination. 3. End-user workstations, or client workstations, have access to entire patient /study database of archive server. 4. Every time an exam is retrieved to a workstation from the archive server, exam images are uploaded directly to the workstation s memory for viewing. 5. When the user completes reading/reviewing of the exam, all the data are deleted from memory, leaving no image data in local storage on the client workstation. (Reference No.7) Advantages: (1)All PACS exams are available for reading or reviewing at any time. (2) There is no need for study delivery. (3) There is no need for query/retrieve function. Every user selects the exam from the work list on the client workstation and images are loaded automatically. Disadvantages: (1) All the PACS system depends on the way the PACS server works. If a failure happen in the server or if it goes down, the entire system will stop working. 13

15 (2) In the client/server model there are many database transactions an this has the result all the system to be exposed to many transaction errors. (3) The client /server model has a structure that is totally dependent on network performance Web-Based Model PACS Web-based model resembles to the client/server architecture and is more focus to the data transaction. Though, the main difference is that in web based model the software in the client s workstation is a Web-based application. Additional advantages as compared with client/server: (1) The only limitation in client s hardware is the support of the web browser. (2) The system runs over a very flexible application as it be used where ever exist an internet connection. (Reference No.7) Additional disadvantages as compared with client/server: (1) The system can be confined in the amount of operations and efficiency by the web browser. 2.2 PACS Contributors Modalities Modality is the professional description of diagnostic imaging devices, which allows physicians to make precise diagnosis by bringing out interiors of the human body without anatomical processes. Many types of modalities can easily be found in modern hospitals, such as Magnetic resonance imaging (MRI), Computed Tomography (CT), Computed Radiography(CR), Ultrasound(US), Positron emission tomography (PET), and Nuclear Medicine(NM). The diagnostic images generated from these modalities save distinctive characteristics. For example, CR focuses the x-rays on the patient plane while CT focuses the x-rays on the crosssection plane of the patient. Furthermore, MRI images provide most contrast images between normal and damaged tissues while NM images are best in presenting the existence and size of abnormalities in the body organ. With the availability of these medical imaging technologies, a physician can ask for many different scans and angles to purchase anatomic views of the patient in order to make the most precise diagnosis. Twenty years ago, radiologists would only receive x-ray films a few 14

16 hours after the scan was performed. With the introduction of PACS, radiologists and physicians can directly have an image at the workstation where they can edit it and make report for the patient. (Reference No.11) Hospital Information System (HIS) HIS is used for administrating hospital and managing clinical processes. It is also called ADT because the Admission, Discharge, and Transfer of patients information are recorded via the HIS interface. HIS is responsible for ordering patient examinations among all healthcare organization departments. When a patient is admitted to a hospital, demographic data of the patient are recorded into HIS. (Reference No.5)This information is sent automatically and electronically to RIS, PACS, and modalities. As a result, spelling errors of patient demographic data at large number of IT systems and diagnostic devices are minimized. Another benefit of HIS is its billing capability in billing procedures as it automatically records charges to many kind of services such as bed, laboratory tests conducted, medicine used, consultation fee, food, and beverages. In some hospitals, HIS maybe connected to many automation systems in order to improve production and patient safety. (Reference No.15) Radiology Information System (RIS) RIS is used in the radiology department for patient management, film and supplies control and scheduling and tracking diagnostic procedures. When a physician ask a technologist to perform an examination on a patient, the scheduled procedures will be ordered through RIS. Automatically, all examination procedures and patient s demographic data are sent to PACS. Modalities and PACS are automatically informed about all updates, changes or corrections that are performed in patients demographic information through RIS. RIS Allows the technologist to simply select a patient and procedure at the modality and patient demographics are included with the resulting images once procedure is completed. Moreover RIS gives the opportunity in administrating the clinical workflow in the radiology department in a more efficient manner(reference No.4) 15

17 2.3 PACS Components Database Server (DBS) The Database Server (DBS )is the local database of the acquisition gateway records structurally the textual information about images, problematic Figure Database server images, queues, and imaging devices. As all the textual information is deleted after the archiving of an exam, small-scale DBS, such as Access and MySQL commercial products, is adequate to support normal operation of image acquisition to the gateway. The DBS mounts extendable database file(s) in which the textual data is actually stored(reference No.11) More General, Database Server is an noracle or SQL Server that controls the entire cluster. Its responsibilities include: storing the central database used by all components in the cluster, maintaining a record of all database transactions in transaction log files, monitoring system activity levels and predicting the amount of database table space needed in the future The Oracle or SQL database manages and shares information related to study attributes, system configuration, user accounts, study mark-up, and annotation of studies. Finally it collects, organizes, and manages all patient and study demographic data that is contained in DICOM header files. (Reference No.11) Network Gateway - Workflow Manager (WFM) The Workflow Manager (or Network Gateway) controls the studies coming into the cluster from an acquisition station. It validates incoming studies against 16

18 information from the HIS/RIS and routes validated studies to the Application server where smart clients cached Display Stations, to the Archive, and so on. Figure Network Gateway If studies are not validated, they are considered broken but are still routed and can be viewed at Display Stations. The Network Gateway is an important part of routing because it checks with the Archive to determine whether any priors for the incoming study can be routed to specific Display Stations along with the study. The Workflow Manager acts as the DICOM gateway between the acquisition modalities and the cluster. Workflow Manager is a core component of the world s most advanced image management system. It is 100% DICOM compatible, and validated against every major DICOM implementation available. Its advanced workflow automation features include demographic data validation, automated pre-fetching, routing, and migration of exams between storage tiers. (Reference No.11) Archive Server (AS) An archive is a DICOM compliant solution for long-term storage and retrieval of studies from long-term storage. It consists of a computer with a media archive or HSM file system.. More in depth, the archive server contains many powerful central processing units (CPUs), small computer systems interface (SCSI) data bases, and network interfaces (Ethernet and ATM).With its redundant hardware configuration, the archive server can support many processes running in the same time, and image data can be propagated through varioust data bases and networks. Moreover, the archive server acts as a PACS controller, managing the direction and the distribution of the images within the entire PACS, from the 17

19 modalities and the acquisition stations to many different destinations such as archive stations workstations, or printer stations. (Reference No.11) In general, the Archive Server is responsible for archiving images when they arrive.the exams are temporarily stored on hard disk (cache) and are eventually stored on long term storage media in the archive. If a user requests an exam that exists in the archive cache, the images are sent immediately. If the images exist only on long-term storage media, the images must be retrieved from the archive, which takes longer. (Reference No.11) Archive Servers configurations vary between media based and fully disc based solutions. In media based solution an archive can be set up in a jukebox configuration that has one or more drives where media is loaded, multiple slots that hold the media for easy storage retrieval, and a robotic changer to move media around within the jukebox. Depending on the media type, an archive may be supported using SCSI, E-IDE (ATAPI), USB, IEEE 1394, or USB 1.1/ Applications Server (APS) The application Server provides web services for the PACS Unified Smart Clients and all integrated components such as RIS and specialty applications. It replaces direct connections to PACS Server components by acting as a proxy and providing services, such as user authentication to PACS Clients. The Application Server sets up connections to the database, RIS, and auditing server, controls logging levels for the web services and establishes the connection to the ADAM server and messaging servers. Application Server is system s license manager as it controls the role that every user has in the system and as the licenses that a user can access are inherited from the roles in which a user is a member APS controls licenses. Moreover Application Server is responsible to install and generate requests for SSL certificates, manage web services and create administration accounts for PACS. Application server uses SSL certificates to encrypt and protect any information passed between the Servers and the Clients in the cluster, including user information, patient image data, and protected health information. Furthermore SSl certificates are used in order to encrypt and protect any information passed 18

20 between the Application Server and other directory servers such as those located outside the cluster and in the hospital network. (Reference No.11) Curator When accessing PACS through the Internet, connection speeds are typically much slower than within the hospital network. To minimize the effect on users, curator processes images in the image cache, creates wavelet images, and stores the wavelet images in the web cache. Using these wavelet images, PACS can display a low-resolution view very quickly and can automatically update the display with higher resolution views as they cross the network until the required resolution of the image has been retrieved. The wavelet images can be accessed by clients locally on the network or clients connected through the Internet. (Reference No.11) Figure illustrates the general flow of images between the image cache and the web cache: Figure Curator (Reference No.11) Curator compresses the appropriate objects using the Mitra Wavelet compression algorithm and stores them in the web cache. For each object in the study, If wavelet compression is required, the object is processed, compressed and stored to the web cache. Curator generates a new DICOM header for each image. If wavelet compression is not required, the object is copied to the web cache Clients PACS combines the traditional activities of RIS informatics management with PACS image management to provide a powerful platform for imaging-based planning, interpretation, and results distribution. PACS Client focuses on the integration of PACS, RIS, and Speech applications into a single delivery of information. A single PACS Client application can be used by a range of users on any appropriate, networked workstation they have access to. PACS provides 19

21 clinical viewing and editing tools for images and full exams in order to write a diagnosis, to a variety of users in- and outside the enterprise, using Smart client technology. (Reference No.8) 3. PACS Workflow In this chapter the workflow of o Picture Archive and Communication system will be presented. This paragraph presents the workflow of this system from the time a patient enters a hospital, his registration to hospitals information system, the examination ordering, to the performance of the examination from the radiographer, the diagnosis the reporting and the archiving of patients data and exam. Through this chapter will be obvious that Picture Archive and Communication System has replaced the most phases of the film based workflow Figure 3.1 PACS Workflow(Reference No.16) 3.1 PACS /HIS/ RIS Work Flow 1. Patient registration in Hospital Information System. Examination ordering in Radiology Information System and en exam accession number automatically assigned. 20

22 2. Radiology Information System sends HL7 messages of Hospital Information System and Radiology Information System demographic data to PACS. 3. Archive server is informed from the PACS broker for the patient scheduled exams. 4. Older exams of the scheduled patient are send from the archive server to the radiologist diagnostic station. 5. Patient arrives at modality. Modality queries PACS for DICOM worklist. 6. The radiographer performs the exam and sends to PACS images and patient demographic data in DICOM format for Quality Control 7. The radiographer sends through PACS to the radiologist diagnostic station the exam as prepared status. 8. When the PACS exam arrives at the radiologist diagnostic station, it is also wend to the archive server. 9. Then the Archive server automatically delivers PACS exam to the diagnostic stations that follow patients location based on the data of the HIS/RIS HL7 message. 10. The radiologist makes the diagnosis of the exam and writes down a report using the patient s accession number. Radiologist signs off on the exam and the Archive Server updates the exam with any changes and annotations that the radiologist did Then the exam data through the accession number corresponds to patients data within RIS. 12. RIS exports an updated HL7 message of results. 13. Radiologist queries PACS for older exams or reports on his diagnostic station. 14. Referring doctors query PACS for reports on their workstations. (Reference No.16) 3.2 PACS and Tele-Radiology This paragraph refers the connection between teleradiology and PACS. There are presented the two models of teleradiology and PACS the clear teleradiology model and PACS and teleradiology combined. (Reference No.16) 21

23 3.2.1 Clear Teleradiology Model In clear teleradiology model, teleradiology can acts as a separate system working by itself (Figure 3.3.1). This model works better for some small imaging centres and small hospitals with a normal radiological examination workflow but with no radiologist to read the examinations and make the diagnosis. In this model the teleradiology management centre acts as the monitor. (Reference No.16) It has the role of a main central station that receives images from many different imaging centres, it makes reports for these images and then it routes this images to the appropriate expert centres for diagnosis. After the reports return to the main management centre, it records the diagnosis and forwards reports to the appropriate imaging centres. This teleradiology model is usually used for night and weekend coverage. Figure Clear teleradiology model. (Reference No.16) PACS and Teleradiology Combined Model Picture Archive and Communication System and teleradiology can cooperated as shown in Figure The two main parts of this system is PACS as shown in Figure A and the clear teleradiology model shown in B. The workflow of this model is as follows: A. PACS reading of the exams from different outside imaging centres (1). 22

24 B. Internal radiologists read the outside exams, they make the diagnosis from internal diagnostic workstations(2) and then they sent the reports to the database gateway for its internal use(3) and to the external centre that send the image(4) C. PACS can also sen exams direcly to the external expert centers(5) and receive from them the report of the diagnosis(6) D. PACS can also send images to the expert centre for reading as in the clear teleradiology model (7). The combined teleradiology and PACS model is usually used in a healthcare centre with satellite imaging centres or in backup radiology coverage between the hospital and imaging centres. (Reference No.16) Figure PACS and radiology combined model. (Reference No.16) 4. PACS Communication Protocols Industrial Standards (HL7 and DICOM) and Work Flow Protocols (IHE) Data transfer through healthcare information systems was always very difficult mainly for two reasons. Firstly, information systems use various computer platforms and secondly medical data and patient images are generated from many different kinds of imaging modalities and several manufacturers. 23

25 In order to integrate al these different and heterogeneous, medical images and textual data in an united and organized system, health care industry standards such as Health Level 7 (HL7) and Digital Imaging and Communications in Medicine (DICOM), were created. Integrating healthcare components requires two components, a common data format and a communication protocol. HL7 is a standard textual data format, while DICOM includes data format and communication protocols. The role of HL7 standard is to establish communication through healthcare components an make possible to exchange healthcare information between hospital information system (HIS), radiology information system (RIS), and PACS. DICOM standard is the translator for the medical images that are generated from different modalities and from different manufacturers and establish the communication and the integration through this kind of modalities. DICOM is the main standard for the healthcare sytems integration an interface. Finally, in order to drive the adaptation of standards the protocol IHE(Integrating the Healthcare Enterprise)was created 4.1 The Health Level 7 Standard Health Level 7 Health Level 7 (HL7), was created in March 1987 from a commission established by users and vendors, in order to develop a standard for data interchange through electronic networks. This standard would properly take place in healthcare environments, mainly for hospital applications. The HL7 standard, the Level Seven, refers to the highest level of the Open Systems Interconnection (OSI). This highest level, is the application level, and is common for multiple vendors. This standard emphasizes data format and protocol for exchanging certain key textual data among health care information systems, such as HIS, RIS, and PACS. Although Health Level 7 is intended to the highest level (level 7) of the OSI model of the International Standards Organization (ISO), it does not comply specifically with the defined facts of the OSI s seventh level. It complies with the semantic definitions of an application-to-application interface placed in the seventh layer of the OSI model. These definitions were created in 24

26 order to make easier and more particular, all the healthcare data communications by establishing particular rules to convert abstract messages associated with realworld events into strings of characters comprising an actual message. (Reference No.4) New Trend in HL7 The most commonly used HL7 today is Version 2.X, which has many options and is thus flexible. During the past years Version 2.X has been developed continuously, and it is widely and successfully implemented in health care environment. Version 2.X and other older versions use a bottom-up approach, beginning with very general concepts and adding new features as needed. These new features become options to the implementers so that the standard is very flexible and easy to adapt to different sites. (Reference No.4)However, these options and flexibility also make it impossible to have reliable conformance tests of any vendor s implementation. This forces vendors to spend more time in analyzing and planing their interfaces to ensure that the same optional features are used in both interfacing parties.there is also no consistent view of the data when HL7 moves to a new version or that data s relationship to other data. Therefore, a consistently defined and object-oriented version of HL7 is needed, which is Version 3. The initial release of HL7 Version 3 was in December The primary goal of HL7 Version 3 is to offer a standard that is definite and testable.version 3 uses an object-oriented methodology and a reference information model (RIM) to create HL7 messages.the object-oriented method is a top-down method.the RIM is an all-encompassing, open architecture design at the entire scope of health care IT, containing more than 100 classes and more than 800 attributes. RIM defines the relationships of each class. RIM is the backbone of HL7 Version 3, as it provides an explicit representation of the semantic and lexical connections between the information in the fields of HL7 messages. Because each aspect of the RIM is well defined, very few options exist in Version 3. Through object-oriented method and RIM, HL7 Version 3 will improve many of the shortcomings of previous 2.X versions. Version 3 uses XML for message encoding to increase interoperability between systems. This version has developed the Patient Record Architecture (PRA), an XML-based clinical document architecture. It can 25

27 also certify vendor systems through HL7 Message Development Framework (MDF). (Reference No.4)This testable criterion will verify vendors conformance to Version 3. In addition, Version 3 will include new data interchange formats beyond ASCII and support of component-based technology, such as ActiveX and CORBA. As the industry moves to Version 3, providers and vendors will face some impact now or in the future, such as: Benefits: 1. It will be Less complicated and less expensive to build and maintain the HL7 interfaces. 2. HL7 messages will be less complex, and therefore analysts and programmers will require less training. 3. HL7 compliance testing will become enabled. 4. It will be easier to integrate different HL7 software interfaces from different vendors. Challenges: 1.Adaption of Version 3 will be more expensive than the previous version. 2. Adaption of Version 3 will take time to replace the existing version. 3. Retraining and retooling will be necessary. 4. Vendors will eventually be forced to adapt Version Vendors will have to support both Versions 2.X and 3 for some time. HL7 Version 3 will offer tremendous benefits to providers and vendors as well as analysts and programmers, but complete adaption of the new standard will take time and effort(reference No.4) 4.2 The Dicom 3.0 Standard History With the introduction of computed tomography (CT) followed by other digital diagnostic imaging modalities in the 1970's, and the increasing use of computers in clinical applications, the American College of Radiology (ACR) and the National Electrical Manufacturers Association (NEMA) recognized the emerging need for a standard method for transferring images and associated information between 26

28 devices manufactured by various vendors. (Reference No.20)These devices produce a variety of digital image formats. The American College of Radiology (ACR) and the National Electrical Manufacturers Association (NEMA) formed a joint committee in 1983 to develop a standard to: -Promote communication of digital image information, regardless of device manufacturer -Facilitate the development and expansion of picture archiving and communication systems (PACS) that can also interface with other systems of hospital information -Allow the creation of diagnostic information data bases that can be interrogated by a wide variety of devices distributed geographically. (Reference No.20) ACR-NEMA Standards Publication No , published in 1985 was designated version 1.0. The Standard was followed by two revisions: No. 1, dated October 1986 and No. 2, dated January ACR-NEMA Standards Publication No , published in 1988 was designated version 2.0. It included version 1.0, the published revisions, and additional revisions. It also included new material to provide command support for display devices, to introduce a new hierarchy scheme to identify an image, and to add data elements for increased specificity when describing an image. These Standards Publications specified a hardware interface, a minimum set of software commands, and a consistent set of data formats. (Reference No.20) DICOM Standard Digital Imaging and Communications in Medicine (DICOM) standard, embodies a number of major enhancements to previous versions of the ACR-NEMA Standard. In depth, DICOM is applicable to a networked environment as it supports operation using the industry standard networking protocol TCP/IP. DICOM supports operation in an offline media environment using industry standard media such as CD-R and MOD and logical file systems such as ISO 9660 and PC File System It specifies how devices claiming conformance to the Standard react to commands and data being exchanged..furthermore, it specifies levels of conformance as DICOM explicitly describes how an implement or must structure a Conformance Statement to select specific options. DICOM is structured as a multi-part document. This facilitates evolution of the Standard in a rapidly evolving 27

29 environment by simplifying the addition of new features. ISO directives which define how to structure multi-part documents have been followed in the construction of the DICOM Standard.It introduces explicit Information Objects not only for images and graphics but also for waveforms, reports, printing, etc.finally, it specifies an established technique for uniquely identifying any Information Object. This facilitates unambiguous definitions of relationships between Information Objects as they are acted upon across the network.(reference No.20) DICOM Data Format In this paragraph there will be dercibed two topics in DICOM data format: the General DICOM Communication model and the DICOM file format. The format is used to define the hierarchical data structure from patient, to studies, series, and images and waveforms. The latter describes how to encapsulate a DICOM file ready for a DICOM SOP service. (Reference No.20) The General DICOM Communication model The general DICOM Communication model determines different real-world objects in the clinical image arena (e.g., Patient, Study, Series, Image, etc.) and their interrelationships within the scope of the DICOM standard. It provides a framework for various DICOM Information Object Definitions (IOD). Figure The General DICOM Communication model Architecture of DICOM Data and Communication Model and DICOM Parts There are two Communication models, the network layers model (left) and the media storage interchange model (right). (Reference No.20) 28

30 Table DICOM Service Classes Service Class Image storage Image query Image retrieval Image print Examination Storage resource Description Provides storage service for data sets Supports queries about data sets Supports retrieval of images from storage Provides hard copy generation support Supports management of examinations (which may consist of several series of management images) Supports management of the network data storage resource(s) Normalized Patient Study Results Storage resource Image annotation Table DICOM Information Object Classes Composite Computed radiograph Computed tomogram Digitized film image Digital subtraction image MR image Nuclear medicine image Ultrasound image Displayable image Graphics Curve (Reference No.20) 4.3 IHE (Integrating the Healthcate Enterprise) What is IHE? IHE is not a standard nor a certifying authority, instead it is a high-level information model for driving adaption of HL7 and DICOM standards. Optimal patient care requires efficient access to all relevant information. Despite the advanced state of technology healthcare enterprises have not yet begun to realize the full potential of computer systems to reduce medical errors, improve the 29

31 efficiency of care providers and enhance the overall quality of clinical care. To do so requires a framework for information sharing that meets the needs of care providers as well as patients and gains acceptance among the companies that build the systems they rely on. (Reference No.13) Standards provide the basis for such a framework, but alone do not solve the problem. In any standard there are gaps, options, room for conflicting interpretations. No standard maps perfectly to the complex and ever-changing information domain of a healthcare enterprise. Filling the gap between standards and systems integration has, until now, required expensive, site-specific interface development. To close that gap a process for building a detailed framework for the implementation of standards is needed. IHE provides that process. Enabling systems to share information effectively, IHE offers a framework for information sharing designed to optimize clinical workflow. Systems implemented in accordance with IHE can streamline the flow of clinical information, reduce errors and improve efficiency. IHE strengthens the information link between different departments for example, between referring physicians and consulting physicians to enable the enterprise to function as a single unit in providing optimal clinical care. (Reference No.13) IHE eases this burden by offering a clear path toward acquiring integrated systems. Referring to IHE Integration Profiles in RFPs and purchasing agreements allows purchasers and vendors to agree on the interoperability of systems being acquired or upgraded, making multi-vendor, best-of-breed solutions more feasible. It enables information technology specialists to concentrate on improving the core functionality of systems, rather than developing and maintaining redundant, pointto-point interfaces. Finally, it makes it possible to implement a streamlined workflow so that care providers can make more efficient use of their time IHE offers a common framework for vendors, IT departments, clinical users and consultants to understand and address clinical integration needs. The IHE Technical Framework allows flexibility while ensuring that key integration needs are met(reference No.13) 30

32 5. PACS Installation in University Hospital of Ioannina 5.1 The Hospital University Hospital of Ioannina was founded in 1986 in city of Ioannina It is located 6 kilometres from the centre of Ioannna, at St. Niarchos Avenue, next to the University of Ioannina. It is one of the biggest University Hospitals in Greece as its capacity is about 882 beds and extents at m2. Figure 5.1 The University Hospital of Ioannina University Hospital of Ioannina provides high quality healthcare services, research and educational work and the latest medical and technological equipment, that makes it the biggest and most complete hospital in west Greece and one of the most innovative and progressive hospitals in the country. As it was mentioned before, University Hospital of Ioannina is one of the biggest University Hospitals in Greece and the biggest and most complete hospital in west Greece. It s geographical position make it able to be in attendance on patients of all the west Greece. As a result, University Hospital of Ioannna has very big press of work, and more specific it covers over of internal and external patients per year. Internal are the patients that were hospitalized in the hospital for some days and external are the patients came to the hospital, made examinations and then they left. (Reference No.2) University Hospital of Ioannina is build on three floors and composed of four main Divisions:1. The Pathology Division, 2.The Surgery Division, 3.The Medical Laboratories, and 4. The Psychiatric Division. Each of the previous divisions embodies some clinics. (Reference No.1) 31

33 In the First Floor there are: 8 Neonatal Department - Neonatal Intensive Care Unit 9 Obstetric Surgery 10 Intensive Care Unit (ICU) - Intensive Care Unit for Cardiothoracic Patients 20 General Surgery - Resuscitation Figure University Hospital of Ioannina First Floor Map(Reference No.1) In the Ground Floor: Ε1 Main Entrance Ε2 Entrance of Outpatient's Department 11 Outpatient's Department 18 Department of Radiodiagnostics [X-Ray/Imaging, including : Computed Tomography (CT), Magnetic Resonance Imaging (MRI) ]- Hemodynamic 16 Nuclear Medicine 17 Renal Unit 15 Roentgenotherapy 19 Laboratories (Biochemistry & Clinical Chemistry, Haematology, Microbiology Laboratory, Pathologic Anatomy, - Histopathology) 33 Restaurant, Cafeteria Figure University Hospital of Ioannina Ground Floor Map(Reference No.1) 32