The term "medical enterprise", used to identify health careinformation systems, is gaining popularity. However, the terminology andtaxonomy is confusing because it mixes the terms and uses of hospitalinformation systems, office information systems, administrative systems, andclinical information systems. Of course, these systems are not disjoint-theyhave considerable overlap and redundancy. Hasselbring proposed anobject-oriented modeling system that can be used to present a taxonomy inovercoming confusion with terminology in this area.1

The taxonomy modeling of an enterprise system, as shown in figure 1,provides a coarse classification of the functional elements of such a system,not a detailed decomposition into technical subsystems. The individual elementscomposing the model shown in figure 1 are the following:

The archive-An electronic warehouse for archiving medical data and images.Sometimes these are called "digital libraries"2 or a "datawarehouse".3

HIS/RIS (health information system/radiology information system)-The HISservices and links the hospital administration system, the clinical informationsystem (clinical decision support system, clinical research system, clinicalassessment, clinical outcomes analysis system), the nursing information system,the laboratory information system, and the patient monitoring system. The RISsupports the management of radiology information including generation andarchiving of radiology consultation reports, billing information transmitted tothe HIS, and interpretation of images in multiple departments.

Picture archiving and communication systems (PACS)-PACS are image managementinfrastructures for the functions of image acquisition, transmission, display,archival, and image data security for intranet distribution.

Workflow engine--This is a rules-based system for managing workflow ofmedical data and images (such as folder management); it automates the currentflow of patient information and medical images both within the radiologydepartment and throughout the enterprise to improve efficiency.

Magnetic server--Often, the archive system might be implemented with opticalmedia and a magnetic server would be used as an intermediate high speedarchive, enabling high data-rate archiving to workstations of medical data andimages. The magnetic server provides client/server transactions services to theclient workstations.

Database-The database provides for the structured query language (SQL; adatabase access interface) searching for specific medical data and images.

Document server--This provides for the management of documents that wereinitially recorded as analog text data and then converted to digital data.

DICOM agent--This aspect of an enterprise system is a communications gatewaythat provides open system connectivity by accepting any digital imaging andcommunication in medicine (DICOM) standard; it accepts any DICOM imagestransmitted into the enterprise (from the various imaging modalities) and iscapable of automatically routing these images to the appropriate locationswithin or outside the department.

Compression engine--When necessary, image data compression, for the purposeof faster transmission and easier, more compact storage, is accomplished usingsuch algorithms as wavelet compression or JPEG compression.

Grayscale workstations--Grayscale workstations are equipped with highresolution display monitors (2048 ¥ 2560, 5 to 8 MegaPixels, or 1280¥ 1024 resolution). These workstations generally offer Windows NT as anoperating system, and a medical imaging viewer system integrated with aninformation systems/medical data software display package. The workstationsfunction as terminals for accessing and interpreting all radiology information,and for transmitting the data to the next destination.

Other functions that may be included in theenterprise system include the following:

Health level seven (HL/7)--This is a standard application protocol forelectronic data exchange in healthcare systems. This standard definestransactions for transmitting patient data among healthcare systems. HL/7components define who the patient is (patient's name, medical record number,order/accession number), while DICOM defines what digital images are availableon the system for the patient.

Prefetch agent-This software agent is used to acquire images on the basis ofselected "pull" events or notices. The images are taken from onearchive and sent to the storage system on the workstation.

Image server-This provides client/ server transaction services to the clientworkstations. It tells the system where images are located so that they can besent to the appropriate destination.

Integrating the healthcare enterprise (IHE)

The IHE is an initiative of the Healthcare Information and ManagementSystems Society (HIMSS, 230 E. Ohio Street, Chicago, IL 60611) and theRadiological Society of North America (RSNA) (820 Jorie Boulevard, Oak Brook,IL 60523). The goal of HIMSS and RSNA via IHE is to promote enterpriseinformation sharing through a series of demonstrations. This initiative isplanned for the RSNA 1999 Meeting in Chicago and the annual HIMSS Conference inFebruary 2000. According to the IHE plan, the initial demonstrations willconcentrate on continuity and integrity of data exchange between informationand imaging systems serving radiology departments.4 The IHE initiative followsa similar promotional plan by RSNA for the DICOM standard for transferringmedical images and medical data between information and medical imagingsystems. The DICOM standard has gained acceptance among radiologists andequipment vendors.

The hospital enterprise

Chang and co-authors presented the requirements and problems of anenterprise-wide system.5 This blueprint for the system is required reading foranyone participating in planning or implementing such a system. As pointed out,an enterprise system requires that many disparate systems and databasescommunicate and interoperate. Software which could provide interoperability andunity systems, and extend the life of disparate systems, is known as commonobject request broker architecture (CORBA).6 CORBA defines middleware that cansubsume every other form of existing client/ server middleware. CORBA wasdesigned to allow intelligent components to discover each other and interact onan object bus. This bus allows objects to make requests to and receiveresponses from other objects located locally or remotely. The client is unawareof the mechanisms used to communicate with, activate, or store the objects.

The combination of CORBA and Web technology, using the JAVA language,7provides network communication between Web clients and servers. JAVA bytecodesare downloaded from a server and executed locally by the client. Web technologyuses both CORBA and JAVA, as JAVA provides portability and CORBA provides thenecessary interoperability for the ideal enterprise-wide system.