Subsystem throughputs of a clinical picture archiving and communications system.

We measured the throughtput rates of individual picture archiving and communications system (PACS) subsystems including the acquisition, archive, display, and communication network as a basis of evaluation the overall throughput of our clinical PACS. The throughput rate of each PACS subsystem was measured in terms of average residence time of individual images in the subsystem. The residence time of an image in a PACS subsystem was determined by the total time the image was required to be processed within the subsystem. The overall throughput of the PACS was measured as the total residence time of an image in the various subsystems. We also measured throughputs of the PACS subsystems using three types of networks (Ethernet; fiber distributed data interface; and UltraNet, UltraNetwork Technologies, San Jose, CA), and the results were compared. Approximately 200 gigabytes of data transactions including magnetic resonance, computed tomography and computed radiography images from our PACS were analyzed. Results showed that PACS throughput was limited by three major factors: (1) low-speed data interface used in the radiologic imaging devices and archive devices; (2) competition for systems processing time among the PACS processes; and (3) network degradation caused by heavy network traffic. We concluded that PACS performance could be improved with a well-designed network architecture, a job prioritizing mechanism, and an image routing strategy. However, device-dependent low-speed data interface has limited PACS performance.