Thinking big: Regional PACS take shape

Large size helps in the world of digital image management

By: Paula Gould

Purchasing a PACS is no longer a step into the unknown. PACS has become well established as a viable technology in medicine. Pilot projects and trials in pioneering hospitals have demonstrated the feasibility of filmless radiology in clinical practice, and today's products meet industry standards and make use of robust, off-the-shelf hardware. Would-be buyers have every right to feel confident that their new digital imaging management system will live up to expectations.

Evidence of this newfound confidence is apparent in the growing scale of PACS projects in Europe, several of which were showcased at EuroPACS 2002. District networks linking nearby hospitals and clinics are finding favor with project managers over smaller, self-contained systems. Proponents of ambitious schemes claim to have "one of the largest PACS in the world," if not the largest, depending on their modesty. Size clearly matters in the world of digital image communication and management.

Realizing the true potential offered by PACS means thinking big, according to Dr. Nicola Strickland, a consultant radiologist at the Hammersmith Hospital in London. While this should not rule out step-by-step soft-copy implementation, managers should regard hospital-wide or institution-wide PACS as their ultimate goal.

"This is in order for the efficiencies of the PACS to be realized, so that film can be withdrawn, so that we can reduce the number of staff, and so that the PACS can work in the way in which it was designed to work," she said. "It is this efficiency of a hospital-wide or area-wide environment that is the major benefit of PACS as a whole."

Strickland believes that enabling this efficiency means reengineering clinical workflow, which is only possible with a hospital-wide (or larger) system. Radiologists are not the only ones who will have to change their habits, she said. Computerization alters the entire process from examination ordering through image viewing and distribution of the final report. Complete reengineering should also include the total withdrawal of film, however radical this might seem.

"Many institutions go as far as introducing PACS, and then they have some difficulty in withdrawing film," she said. "None of us like to change working from one way to another, but it is an absolutely, fundamentally crucial step-sometimes a brutal step-to withdraw that film."

She cites electronic remote requesting and speech recognition as two means of realizing further efficiencies with a hospital-wide PACS. The former offers a way of becoming paperless as well as filmless, while the latter would sidestep typing delays that hold up report delivery. Because images are available instantly with a PACS, any wait for clinical reports to be word processed is increasingly evident.

These improvements in healthcare efficiency provide a more appropriate way of assessing a PACS, instead of considering the technology solely in terms of cost-effectiveness, Strickland said. She contrasted demands to justify spending on a PACS with the evaluation of a new CT or MR scanner. Discussion of these modalities focuses on improved patient management, not financial savings. Like CT and MR, PACS should be measured in terms of improving services.

ADDED VALUE

Hospitals within the state of Styria, Austria, are demonstrating the additional service benefits of a large-scale PACS. The Styrian Hospital Organization manages 20 hospitals at 23 locations, including the 1800-bed University Hospital in Graz. All nine radiology institutes within the hospital group share an in-house RIS and a PACS.

A total of 92 modality stations are connected to the digital image management and communication system, which can be accessed from 53 reporting workstations, according to Prof. Dr. Gunther Gell of the Institute for Medical Informatics, Statistics, and Documentation at University Hospital Graz. The addition of 1200 PC workstations installed with in-house DICOM viewing software allows doctors to review clinical images from the ward, their office, and the operating theater.

University Hospital Graz generated 3.2 GB of image data from 25 modalities in 2001, and current archive capacity is running at 21 TB. With the RIS/PACS infrastructure now in place, the Styrian Hospital Organization can archive images produced at hospitals and radiology institutes outside the network, Gell said. The scheme, which is being run in collaboration with Siemens, offers storage and image management service to external users at Euro 0.225 per MB, including data transfer and 10 years' archiving.

"Once you have the infrastructure in place for distributing images, many applications spring up," he said.

Work is under way to update the RIS, which dates back several decades, and link all 20 hospitals to an integrated HIS. Doctors want to access clinical images and patient data from one comprehensive system, Gell said. The lack of a master patient index also results in differing patient ID codes in the present HIS and RIS.

He foresees that a statewide integrated PACS/HIS/RIS will provide a valuable resource for research, teaching, and evaluation of patient outcome. Full implementation of the system at all Styrian hospitals, however, and generation of the benefits will take several years, he said.

Meanwhile, a districtwide PACS project in Finland is on schedule to link 21 neighboring hospitals to a common image database by the middle of 2003. The ambitious scheme, known locally as HUSpacs (for the hospital district of Helsinki and Uusimaa), will also eventually accommodate remote network logins by offsite consultants and external physicians based at 53 primary healthcare centers, nine primary healthcare hospitals, and private clinics.

The giant HUSpacs digital image management system could well be the largest PACS project in the world. When fully functional, it will support imaging services throughout the district, which is home to almost 1.5 million people, a quarter of the Finnish population. Installation of the PACS, which is being supplied by Agfa in a multimillion euro deal, will have extended to 17 hospitals by the end of 2002.

"We aim to have seamless radiological services throughout the community, in hospitals, in the whole organization. We need images and reports to be available, so there is no need to move the patients," HUSpacs project leader Anita Suhonen told delegates attending a precongress virtual tour at Helsinki University Hospital. "We can have centers of excellence for medicine because we can retrieve reports from different places."

The completed HUSpacs is expected to handle 20 TB of imaging data each year, produced from about one million examinations performed on 300 connected modalities. Each hospital or hospital group will have sufficient short-term redundant array of inexpensive disks (RAID) to keep images and reports online locally for one to two years. Long-term and backup archiving will be provided in a single, regional database run according to an application service provider (ASP) model.

At hospitals already linked to the network, requests and scheduling information input to the RIS are relayed to the PACS via brokers as HL7-standard messages. The brokers produce work lists for each connected modality and send an overnight command to the regional archive to retrieve previous imaging examinations, according to predefined criteria. New images are transferred to the RAID, while the broker updates patient examination information. Radiologists may then access the images on dedicated dual-screen radiological workstations, before dictating reports to the RIS. Clinicians can retrieve both images and reports using Web browser technology on standard PCs.

Integrating primary healthcare units into the network is crucial if the regional project is to become a genuine community PACS, according to Dr. Hanna Pohjonen, a consultant for HUSpacs. Two routes should be open to general practitioners wishing to access image data: First, examinations requested from primary healthcare physicians should be routed to the unit's Web server from whichever radiology departments within HUS they were obtained in. The ordering physician would then view these images on a PC. Previous examinations performed in HUS, but not requested from that particular unit, should be retrieved from a regional "reference database." Finnish law requires patient consent for these requests.

"We think it is safe to say that point-to-point telemedicine is dead. It has been replaced by regional solutions and the reference database," she said. "Information is not sent anymore, it is viewable."

Pohjonen is hopeful that the huge technological investment in HUSpacs will produce real service benefits, both across the networked region and beyond. Remote reporting is already proving popular with consultants, enabling offsite and evening work. Networked teleconsultations could reduce the number of doctors needed on call and allow specialists to direct certain imaging procedures or operations from a distance, she said.

BE PREPARED

Security and privacy of patient data are high priorities in the HUSpacs project-not surprising, given the large number of potential users. Researchers are developing a strong authentication procedure for remote login, using a wireless public key infrastructure (PKI). The proposed system will take advantage of mobile phone technology, relying on the wireless identification module (WIM) embedded in handsets to identify the user.

The procedure is expected to be relatively straightforward. A doctor connecting to the network from outside one of the 21 linked hospitals will be prompted to key in his or her mobile phone number at the computer login screen and will then receive the particular session ID (the public key). Shortly afterward, a text message will arrive on that physician's mobile phone. If the digits sent to the phone match the session ID, pressing "sign" sends back a message that the two are identical. The physician may then enter a pre-allocated secret PIN on the computer login screen to complete the connection.

Pohjonen acknowledges that PKI has yet to catch on in countries outside of Scandinavia. Most existing strong authentication PKI solutions in Finland rely on smart cards, which are issued and regulated by local authorities.

"We trust explicitly in these PKI solutions," Pohjonen said. "We should also have digital signing of requests and reports. That is something we are very keen on."

Pohjonen and her colleagues also trust external vendors to keep HUSpacs up and running. A usability agreement guarantees network functionality for at least 99.98% of the year. This corresponds to an annual downtime of 1.7 hours, which can still be serious in a project of this size. Round-the-clock hardware and software maintenance for the PACS, seven days a week, is part of the agreement as well.

Dr. Keith Foord, a consultant radiologist at the Conquest Hospital in Hastings, U.K., knows only too well the importance of reliable vendors and watertight maintenance contracts. Company takeovers, rapid technological change, and occasionally unsatisfactory equipment have provided many headaches and challenges since the installation of a very basic PACS at the Conquest Hospital in 1991.

Over a decade of experience and several overhauls later, the Conquest is running on an even keel and linking up with the PACS at nearby Eastbourne Hospital. An integrated cancer network across the county of East Sussex has also been suggested, with possible expansion to a larger area of southeast England.

"'Go with a big company, this is stable,' we thought. But stability is not guaranteed even with a big company," Foord said.

Predicting exactly when, how, and why a digital imaging system will experience difficulties is clearly impossible. So Strickland advises hospitals with PACS to prepare for the worst, taking steps to minimize damage or down time if a technical breakdown occurs. Sufficient redundancy should be built in so that system failure does not affect the whole institution, she said. Procedures should be in place and rehearsed for backing up data, and key replacement parts should be stored onsite.

"Putting in a PACS and withdrawing film is very much like setting off to sea in a ship," she said. "In a way, you're on your own, and you just have to cope. Anybody who has a large-scale hospital PACS and says there aren't any problems is, quite frankly, lying."