Factors affecting performance of PACS.
We experimentally constructed a personal-computer-based Picture Archiving and Communication System (PACS) for color images of dermatology clinics. This system should especially satisfy such a demand as to be able to retrieve an image within a few seconds from the database residing in a remote server. Our two objectives in the experiment were: To examine how much time was consumed in each part of PACS while it does a series of jobs, from the requesting of an image to its display on the screen of the workstation of the user. The other objective was to see if a personal-computer-based PACS could satisfy our criteria. Total retrieving time, data reading time, data transporting time and image displaying time were measured. Total retrieving time can be divided into three procedures: Data reading time, data transporting time, image displaying time. Data reading time was about 0.6 second for reading an image with the size of 1 mega bytes (MB). Data reading time and the size of data were linearly correlated. Data transporting time was about 11 seconds for transporting an image with the size of 1 MB through EtherTalk, and 66 seconds through LocalTalk. Data transporting time and the size of the data were also linearly correlated. Data reading time and data transporting time was able to be reduced largely by compression technique. However, smaller data give other important effects to the network system besides reducing the time of data reading, data transporting and data displaying. Most Local Area using image Network (LAN) systems, such as EtherTalk, adopt Carrier Sense Multiple Access with Collision Detection (CSMA/CD) for the way of accessing to other computer. In CSMA/CD, transporting performance suddenly declines if the congestion of signal in a network gets beyond a critical level. This situation fatally impairs the performance of a network. We concluded that data compression plays an important role to improve the performances of PACS, especially those of a server and the network system. A personal-computer-based PACS with EtherTalk and an image compression/decompression hardware, e.g., CL550A chip, satisfies our criteria.
Masai
E
E
Department of Hygiene, Kobe University School of Medicine.
Ichihashi
M
M
D003880:Dermatology; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000295:instrumentation; D011873:Radiology Information Systems / Q000295:instrumentation; D012680:Sensitivity and Specificity