[Electronic distribution of patient records and images through PACS: implementation of data protection at the University Hospital in Freiburg]

In large installations of a Picture Archiving and Communication System (PACS), data protection becomes an issue. Above all, not every employee should have access to all data stored in the system. At the Freiburg University Hospital, we developed a concept of dynamic assignment of authorization, assuring that every physician is authorized to the data of all patients under his care. We describe the technical implementation of data protection developed for the integration of PACS and electronic patient records in Freiburg. The system was installed in January 2001 and the experience of its two years in operation is reported.

Networks in the radiology department and the hospital

Data networks are a basic technology with regard to an appropriate design of the information technology (IT) infrastructure for the hospital. Due to the distributed workflow within the hospital, an integrated Hospital Information System (HIS) is based mostly on a set of network applications facing specific items. Medical communication standards, i.e., HL 7, DICOM, and in the near future the migration towards XML, support the interoperability between the IT subsystems and pave the way to patient information systems with access to unified and complete electronic medical records (EMR). Furthermore, with standardized communication techniques, such as CORBAmed, an object-oriented design of Healthcare applications will be possible in the near future. The intent of this paper is to give an overview of which basic technologies are suitable for building comprehensive, flexible, and reliable hospital networks and which also meet the special demands of the radiology department.

[Modern network technologies for data communication in the hospital]

Modern network technologies provide the basic infrastructure for information and communication systems in the hospital today. The goal to build up a universal network infrastructure which meets the broadly varied requirements. Analysis of data communication in the hospital and the evaluation of established network technologies, as well as new developments, leads to the switching concept as the suitable solution. Two technologies play the major role in building enterprise networks: the Ethernet family, based on frame switching, and ATM, based on cell switching. Orientation on established standards is the key to free system choice and grants interoperability between systems from different manufacturers. However, the network design must meet the application and system architecture of the information technology in order to achieve successful mapping of the involved communication profiles. This means scaling of the bandwidth as needed, suitable segmenting of the network and resilient links. In a further step, policy-based networking takes advantages of prioritizing critical applications and therefore reduces interdependencies across the network.

Experience with PACS in an ATM/Ethernet switched network environment

Legacy local area network (LAN) technologies based on shared media concepts are not adequate for the growth of a large-scale picture archiving and communication system (PACS) in a client-server architecture. First, an asymmetric network load, due to the requests of a large number of PACS clients for only a few main servers, should be compensated by communication links to the servers with a higher bandwidth compared to the clients. Secondly, as the number of PACS nodes increases, the network throughout should not measurably cut production. These requirements can easily be fulfilled using switching technologies. Here asynchronous transfer mode (ATM) is clearly one of the hottest topics in networking because the ATM architecture provides integrated support for a variety of communication services, and it supports virtual networking. On the other hand, most of the imaging modalities are not yet ready for integration into a native ATM network. For a lot of nodes already joining an Ethernet, a cost-effective and pragmatic way to benefit from the switching concept would be a combined ATM/Ethernet switching environment. This incorporates an incremental migration strategy with the immediate benefits of high-speed, high-capacity ATM (for servers and high-sophisticated display workstations), while preserving elements of the existing network technologies. In addition, Ethernet switching instead of shared media Ethernet improves the performance considerably. The LAN emulation (LANE) specification by the ATM forum defines mechanisms that allow ATM networks to coexist with legacy systems using any data networking protocol. This paper points out the suitability of this network architecture in accordance with an appropriate system design.

Critical success factors for a hospital-wide PACS

Since 1996 a picture archiving and communications system (PACS) is installed at the university hospital of Freiburg. The PACS is integrated in the hospital information system (HIS) and several modalities of different vendors are attached to it. During the implementation phase three critical factors to the success of our PACS installation where identified: the support of the workflow, the interface of the radiological information system (RIS) to the modalities, and the security policy to allow hospital-wide access to the images and results in the PACS.

[RADIOLIS. A radiologic instruction and training system for systematic evaluation of roentgen images exemplified by focal bone lesions]

RADIOLIS is an instructional software system for radiological training that guides the user through a systematic analysis of an image. The backbone of the analysis is a detailed and structured questionnaire which, as applied to our example, includes all relevant differential-diagnostic criteria for focal bone lesions. The variation range of the radiomorphologic characteristics in the questionnaire is introduced to the user with digitized X-ray images, making the simulation of an image analysis possible. In preparation, diverse teaching/learning methods reinforced by instructional psychology were incorporated during the system's development. At the core of the training system are an expandable image database and a database containing descriptions of image material formulated by radiology experts. The field of focal bone lesions, for instance, has already been integrated into RADIOLIS. A graphic user interface and an interactive dialogue enable both comfortable and simple use of the system and the user-specific structuring of the learning process.

[New developments in the computer-assisted diagnosis of focal bone lesions]

Since the 1960s there have been numerous reports in the literature about computer-aided medical diagnosis and therapy. However, so far computer-aided diagnosis has not become important in the clinical routine or in the field of radiology. This paper describes the hitherto existing proposals for expert systems to evaluate focal bone lesions and presents a new concept. The basic ideas of this program are: (1) a PC-based interactive dialogue along on the basis of a defined questionnaire; (2) the use of certainty factors to handle uncertainty and vagueness in evaluating the different radiological findings and their correlation with diagnoses; (3) the link between visual information and the questionnaire. The aims of such expert systems are (a) a complete and systematic analysis of the films, (b) independency of association with previously diagnosed cases in reporting the films, (c) the procurement and use of radiological descriptive terms, and (d) aid in the radiological evaluation of focal bone lesions.