Now that picture archiving and communications systems (PACS) has matured, our challenge is to make the images available to the referring physician and, in a teaching institution, to make these images available for conferences and rounding. One soiution is the distribution of the images using web-based technology. We investigated a web-based add-on to our PACS to determine the characteristics of the personal computer that will make this technology useful and affordable, We found that images can be viewed easily through a web-based system. We found that the optimal system to view these images at a reasonable speed and a reasonable cost is on with a mediumrange processor (200 to 300 MHz) and a large amount of inexpensive RAM, at least 64 Mb. Copyright 9 1999 by W.B. Saunders Company E LECTRONIC RADIOLOGY is maturing rapidly. Picture archiving and communications systems (PACS) are installed in many institutions, and the technology, reliability, availability, and affordability have improved over the last few years. The field has matured so that it is a practical and desirable method of delivering radiologic services. As departments make their way toward filmless environments, new challenges arise. The images, though easily accessible in the Radiology Department, are unavailable at sites traditionally using film, such as conferences, physician rounds, physicians' offices, and preparation of publications. Several solutions are available, including limiting access to the images, printing film, widespread use of expensive workstations, and web technology.Web distribution is an attractive solution as it utilizes standard hardware available in many locations in a modern hospital environment. We are investigating the utility of this technology. The purpose of this presentation is to evaluate the MATERIALS AND METHODSOur institution is a tertiary medical center with 580 staffed beds and several outpatient clinics. We perform 225,000 examinations per year. We are phasing in PACS with the intent of becoming filmless. Currently, we are using a commercially available PACS

Now that picture archiving and communications systems (PACS) has matured, our challenge is to make the images available to the referring physician and, in a teaching institution, to make these images available for conferences and rounding. One solution is the distribution of the images using web-based technology. We investigated a web-based add-on to our PACS to determine the characteristics of the personal computer that will make this technology useful and affordable. We found that images can be viewed easily through a web-based system. We found that the optimal system to view these images at a reasonable speed and a reasonable cost is on with a medium-range processor (200 to 300 MHz) and a large amount of inexpensive RAM, at least 64 Mb.

No abstract

The leakage flow in a 2-D stationary stepped labyrinth seal is investigated by means of flow visualization, pressure field measurements, and Particle Image Velocimetry. The basis of investigation is a generic stepped labyrinth seal currently used by the industry in steam turbine generators. Geometric and flow parameters were varied in order to examine their influence on leakage through seals. Flow visualization results revealed inter-related mechanisms of energy loss in labyrinth seals to include turbulence induced viscous losses, chamber vortex generation, flow stagnation, and increased flow streamline curvature. A five times scale model was constructed and tested over a range of seal pressure ratios from 1:1 to 10:1. Model configurations included a baseline and six variants of the basic design that were conceptually devised to be superior and by varying step height and knife angle. Detail pressure and velocity measurements were carried out. Results show that with relatively minor changes in geometry, determined based on our understanding of the physics of the flow, leakage reductions of up to 17% were accomplished.

This presentation describes our experiences using a web-based viewing software and a browser to view our picture archiving and communication system (PACS) images at a remote site with cable modeminternet communications. Our testing shows that using a cable modem to access our radiology webserver produces acceptable transmission speeds to remote sites. The average time-to-display (TTD) for 16 computed tomography (CT) images on the web-based intranet system in our hospital was 7 to 8 seconds. Using a cable modem and comparable equipment at a remote site, the average TTD is 16 seconds over the internet. The TI'D does not significantly change during various hours of the day. Security for our hospitalbased PACS is provided by a firewall. Access through the firewall is accomplished using virtual private network (VPN) software, a secure ID, and encryption. We have found that this is a viable method for after-hours subspecialty radiology consultation. Copyright 9 2000 by W.B. Saunders Companysystem. Once connected by VPN software, browsing the hospital network acts justas if it were taking place at the hospital. The web server can then be accessed using the browser.A series of tests were pefformed over an 18-hour period (7 AM to midnight). A test of the hospital connection consisted of accessing three computed tomography (CT) scans (two head CTs and one abdominal CT), three computed radiograph (CR) images (five-view C-spine, portable chest, three-view acute abdominal series) anda magnetic resonance image (MRI) of the shoulder. The time-to-display (TI'D) is the time from the moment the display button is selected to the time the display of the images is complete. The TTD for each case was noted. The CTs and MRIs were viewed on a 16-on-1 formar and the CRs were on a 1-on-1 format. The memory was cleared after every test group. The images were stored on the web server with a lossless wavelet compression of 3-to-1. No postserver compression was used. In addition, general Intranet traffie was evaluated by accessing an Australian site to download a 3.7-MByte file, a California site to download a 25-MByte file, anda local site to display web page with graphics and text.