The RSNA Image Sharing Network.

In the era of health information exchanges, there are trade-offs to consider when sharing a patient's medical record among all providers that a patient might choose. Exchange among in-network partners on the same electronic medical records (EMR) and other integrated information systems is trivial. The patient identifier is common, as are the relevant departmental systems, to all providers. Difficulties arise when patient records including images (and reports) must be shared among different networks and even with the patients themselves. The National Institutes of Health (NIH) challenged Radiological Society of North America (RSNA) to develop a transport method that could supersede the need for physical media (for patients or other providers), replace point-to-point private networks among providers, and enable image exchange on an ad hoc basis between arbitrary health networks without long legal delays. In concert with the evolving US health care paradigm, patient engagement was to be fundamental. With Integrating Healthcare Enterprise's (IHE's) help, the challenge has been met with an operational system.

Finding the optimal picture archiving and communication system (PACS) architecture: a comparison of three PACS designs.

PURPOSE: At present, there are two basic picture archiving and communication system (PACS) architectures: centralized with a central cache and controller, and distributed with a distributed cache and central controller. A third architecture proposed here is an autonomous one with a distributed cache and no controller. This report will investigate the performance (as measured be central processing unit [CPU] and network load, scalability, and examination retrieval and display latency) of these three types. METHODS: The distributed PACS architecture will be simulated using an IMPAX R3.5 (AGFA, Ridgefield Park, NJ) PACS, while the centralized design will be simulated using an IMPAX R4 (AGFA) PACS. The autonomous system will be designed and implemented in-house. The autonomous system consists of two types of entities: basic components such as acquisition gateways, display stations, and long-term archives, and registry servers, which store global state information about the individual PACS components. The key feature of the autonomous system will be the replacement of the central PACS controller by the registry servers. In this scenario the registry servers monitor the interactions between the components, but do not directly govern them. Instead each component will contain the application logic it requires and will use the state information from the registry servers to take the appropriate action, such as routing images, prefetching studies, and expiring images from near line cache. In addition the routing of examinations will be optimized to reduce the duplication of image data. Display stations will be categorized by specialty (neuroradiology, pediatrics, chest, etc) and will retrieve studies for display on demand from intermediate servers dedicated to the corresponding specialty. Studies will be routed only to the intermediate servers and not to display stations. RESULTS: By distributing the application logic, an autonomous PACS architecture can provide increased fault tolerance and therefore increased uptime. In addition, the lack of a central controller and the use of intermediate servers improve the scalability of the system, as well as reduce CPU and network loads.

What Digital Imaging and Communication in Medicine (DICOM) could look like in common object request broker (CORBA) and extensible markup language (XML).

Common object request broker architecture (CORBA) is a method for invoking distributed objects across a network. There has been some activity in applying this software technology to Digital Imaging and Communications in Medicine (DICOM), but no documented demonstration of how this would actually work. We report a CORBA demonstration that is functionally equivalent and in some ways superior to the DICOM communication protocol. In addition, in and outside of medicine, there is great interest in the use of extensible markup language (XML) to provide interoperation between databases. An example implementation of the DICOM data structure in XML will also be demonstrated. Using Visibroker ORB from Inprise (Scotts Valley, CA), a test bed was developed to simulate the principle DICOM operations: store, query, and retrieve (SQR). SQR is the most common interaction between a modality device application entity (AE) such as a computed tomography (CT) scanner, and a storage component, as well as between a storage component and a workstation. The storage of a CT study by invoking one of several storage objects residing on a network was simulated and demonstrated. In addition, XML database descriptors were used to facilitate the transfer of DICOM header information between independent databases. CORBA is demonstrated to have great potential for the next version of DICOM. It can provide redundant protection against single points of failure. XML appears to be an excellent method of providing interaction between separate databases managing the DICOM information object model, and may therefore eliminate the common use of proprietary client-server databases in commercial implementations of picture archiving and communication systems (PACS).

Secure, web-accessible call rosters for academic radiology departments.

Traditionally, radiology department call rosters have been posted via paper and bulletin boards. Frequently, changes to these lists are made by multiple people independently, but often not synchronized, resulting in confusion among the house staff and technical staff as to who is on call and when. In addition, multiple and disparate copies exist in different sections of the department, and changes made would not be propagated to all the schedules. To eliminate such difficulties, a paperless call scheduling application was developed. Our call scheduling program allowed Java-enabled web access to a database by designated personnel from each radiology section who have privileges to make the necessary changes. Once a person made a change, everyone accessing the database would see the modification. This eliminates the chaos resulting from people swapping shifts at the last minute and not having the time to record or broadcast the change. Furthermore, all changes to the database were logged. Users are given a log-in name and password and can only edit their section; however, all personnel have access to all sections' schedules. Our applet was written in Java 2 using the latest technology in database access. We access our Interbase database through the DataExpress and DB Swing (Borland, Scotts Valley, CA) components. The result is secure access to the call rosters via the web. There are many advantages to the web-enabled access, mainly the ability for people to make changes and have the changes recorded and propagated in a single virtual location and available to all who need to know.

Network latency and operator performance in teleradiology applications.

Teleradiology applications often use an interactive conferencing mode with remote control mouse pointers. When a telephone is used for voice communication, latencies of the data network can create a temporal discrepancy between the position of the mouse pointer and the verbal communication. To assess the effects of this dissociation, we examined the performance of 5 test persons carrying out simple teleradiology tasks under varying simulated network conditions. When the network latency exceeded 400 milliseconds, the performance of the test persons dropped, and an increasing number of errors were made. This effect was the same for constant latencies, which can occur on the network path, and for variable delays caused by the Nagle algorithm, an internal buffering scheme used by the TCP/IP protocol. Because the Nagle algorithm used in typical TCP/IP implementations causes a latency of about 300 milliseconds even before a data packet is sent, any additional latency in the network of 100 milliseconds or more will result in a decreased operator performance in teleradiology applications. These conditions frequently occur on the public Internet or on overseas connections. For optimal performance, the authors recommend bypassing the Nagle algorithm in teleradiology applications.