<title>Distributed database for a picture archiving and communications system</title>

Abstract

Abstract This paper describes the design of a distributed database for a Picture Archiving and Communications System (PACS). This system consists of several relatively cheap workstations and a large optical archive and distributed database modules. The communication between the modules uses the same network as used to connect the system to the clients. Existing, working andavailable standards are used where-ever possible. This makes the system open and accessible in a multi-vendor environment suchas hospitals. The distributed approach makes the total system flexible, cheaper, faster and when designed carefully, more reliable. 1 Introduction For several years many research groups are working on Picture Archiving and Communications Systems (PACS) for hospitals.Main topics within that area are user interface design, workstation capabilities, high speed networks, cost evaluation and manyothers. Less attention went to the design of a database for PACS. The research project on distributed databases at the Laboratoryof Computer Architecture and Digital Technique (CARDIT) at the Deift University has therefore selected the design of a databasefor PACS as a case study.To store the complete set of images generated in a hospital throughout a few years, an optical and/or tape-archive is necessary.This archive consists of a number of jukeboxes, which contain recent images on optical disks or tapes online and older sets arestored on optical disks offline. The problem addressed in this paper concerns the quick query solving and very fast image retrievalof recent images.The two most important requirements of a PACS are high performance and acceptable costs. Ifthe traditional method of solvingthe performance requirements is used, a huge mainframe with many large high speed disks would be needed [1]. It can be shownthat with such an approach it is difficult to obtain the required response times and moreover such an approach would be ratherexpensive. Distributed and/or parallel databases can be very fast and relatively inexpensive [2, 3.This paper will present the design of such a distributed database for a PACS. This database will exploit parallelism to meet theperformance requirements. In Section 'The Picture Archiving and Communications System' a general environment of PACS willbe described. Section 'Requirements' describes the requirements used in the database design. Section 'The Distributed Approach'describes the system designed.566