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Even the smallest of radiology practices must acknowledge and prepare to invest in electronic archiving of images, experts advise. It is an idea whose time has come. “Even if you’re part of a small three- or four-man group, you’re not part of a small group. People form alliances, allegiances, networks,” says Paul Chang, MD, director of the division of radiology informatics at the University of Pittsburgh School of Medicine and the University of Pittsburgh Medical Center Health System.
What is an electronic archive? With reference to a PACS (picture archiving and communications system), the archive is the picture archiving portion of the system. The hardware and software for image storage can take many forms, from a centralized on-site hard drive for short-term storage, to on-site or off-site optical disks or digital tape for longer term storage, to off-site digital tapes as a disaster-recovery solution.
The simplest archiving system consists of a server, which is a heavy-duty computer capable of quickly handling large amounts of data, hooked to an office refrigerator-sized storage unit called a RAID (redundant array of inexpensive disks), which stores and plays out information on magnetic disks. It can form the backbone of any small archiving system. Of course, it is not that simple. Another of the decisions an electronic archivist must make is whether to become DICOM (Digital Imaging and Communications in Medicine) compliant. DICOM is the computer language that allows imaging devices and computers to talk to one another, and enables images to be transported in a common language among networks. All of the sources for this article advocate DICOM compliance for the archive, even though the software is an investment of several thousand? dollars. DICOM used in tandem with HL-7 (Health Language 7), the computer language for text, allows a total electronic medical record to be configured. According to several sources interviewed, not all of the archives offered by PACS vendors are DICOM compliant. This could present problems when an institution attempts to migrate data from one archive to another, experts say.
The interviews conducted for this story make it clear that archiving electronically must be carefully considered before a commitment is made to a particular system. Any clinic, practice network, hospital, or health system moving to electronic archiving needs to establish:
? cost to operate current imaging delivery and storage system.
? current storage needs
? projected future storage needs
? who will be exchanging data
? the speed with which data will need to be delivered.
The Individual Practice
Austin Radiology Associates (ARA) in Austin, Tex, is a 52-practitioner, physician-owned corporation that since 1954 has been providing imaging services at hospitals and outpatient clinics in the Texas capital. Today, ARA operates 14 outpatient centers, where about 300,000 images are generated each year. Modalities vary with each clinic, but ARA has all the conventional modalities, including CT, MRI, and fluoroscopy. ARA also serves eight Austin-area hospitals, providing the daytime staffing coupled with a nighttime teleradiological reading service. According to ARA’s president, Gregory C. Karnaze, MD, the hospitals account for another 400,000 images yearly.
Surprisingly, perhaps, none of the major hospital chains in Austin has a PACS in place, according to Karnaze. Neither does ARA. The practice currently archives film in warehouses and delivers images manually by couriers. After having spent a year in the selection process, ARA is about to become the first major health care provider in the city to go electronic with a PACS featuring an archiving system organized as a storage area network (SAN), Karnaze says.
According to Todd Thomas, ARA information services director, a SAN is “a high- speed, special-purpose network that interconnects different kinds of data storage devices with associated data services on behalf of a larger network of users.”
The SAN takes the storage disks and separates them from the regular day-to-day operational network of the business. “The SAN creates all the storage on its own network,” Thomas explains. “It allows you to centralize all your storage so that if you wanted to do backup or if you wanted to copy a database, all of that is done on the SAN without affecting your regular operational network. Functionally, from a user perspective, there really isn’t a difference between a SAN and a regular archive. The difference is that, from an information technology (IT) perspective, the SAN is a separate network. Anything that IT needs to do can be done without impacting the regular network.”
The day-to-day system can still talk to the SAN, but it essentially takes all of the storage from all of the system’s individual servers and creates what Thomas called “one big storage pile for everybody to have access to.”
The storage pile is made up of standard 73-gigabyte hard drives arranged to create high-speed throughput and high-speed redundancy. “Instead of having four disk drives in each individual server in the system, I have 120 disk drives for all servers all together,” he explains. “They’re just standard disk drives arranged in such a way as to create very high availability.”
ARA’s PACS and SAN are not minor investments. They will cost at least $8 million, probably more. But projected savings are pegged at $24 million over a 5-year period, according to ARA’s CEO Doyle W. Rabe, CPA. Rabe says ARA is financing its electronic system through cash and bank loans. It also intends to lease storage space on its SAN to hospitals, cardiology groups, and other health care providers. “All the big cardiology groups in town have approached us about our renting the use of our network so they can move studies around,” Rabe says. “We’re also talking with the largest local hospital group about renting storage space to them when they implement PACS rather than their having to duplicate the expensive software of our SAN.” For tax purposes, ARA will purchase its system through a sister corporation organized as a leasing company, and that sister corporation will lease the equipment back to ARA, Rabe adds.
Outright Purchase or ASP
One of the major decisions of ARA management was deciding to purchase its PACS and SAN outright. According to Karnaze and Rabe, going through an ASP vendor to lease the equipment would only have added an unwelcome layer of cost. “We’re a very big installation,” Karnaze says. “The pricing we are getting is as competitive as anybody in the country is getting, so a leasing company cannot buy our system for less. All they can do is add cost and layers of bureaucracy.” Karnaze adds that ARA has protected itself on the obsolescence issue by inserting upgrade options as part of its software purchase agreements. On hardware, ARA has “significant discounts guaranteed if we need to do platform changes,” he says.
ARA’s electronic archive is extremely sophisticated in its configuration because the SAN will also store data generated by the company’s RIS and its accounting department, according to Thomas. All the ARA clinics will be linked in what is called a SONET ring (Synchronous Optical Networking) using fiber-optic lines that are 100 times faster than conventional T1 lines. The lines from each clinic will feed image data in digital format back to the company’s headquarters, where it will be stored on a central archive using conventional magnetic imaging disks. Thomas estimates that the company will need about three to five terabytes of storage each year. The SAN will hold 19 terabytes of data. Using a “hub and spoke design,” each clinic will feed imaging data to headquarters and from headquarters the data will be sent back to differing clinics as it is called for. “The central archive will be like one big hard drive accessible by servers at each clinic, but it will be more complex than that,” Thomas says. The installation of the PACS and the SAN, which is beginning just now, is? expected to take another 6 months to complete.
Still undecided, says Thomas, is if the company will separate its short-term and long-term archiving. Currently, ARA is using a “long and laborious” nightly process to move its digital images to tape as a redundancy, Thomas says, “So if you ask us, we would say keep everything on disk as long as possible. However, disk media is more expensive than tape media.” Thomas notes that the archive will include the creation of a “mirrored copy that is simultaneously updated, so that if our system crashes, we can switch instantly to our mirrored images, so downtime would be minimal.”
Adds Karnaze, “What we would like is to have everything on disk and then go to a higher compression as the images get older. So the first 6 months we would store in a lossless compression mode. But for images 2 years old, we might go to a 10-1 lossy. It’s a tradeoff between speed of access and compression. If you go to a tape, it might take 15 minutes to retrieve, whereas compressed on disk, you can have it right up. We think for CT, MRI, and ultrasound we could go 10-1 without appreciable loss, and for plain films you could go 30-1 if not higher.”
The Hospital
According to Larry Weber, medical imaging manager and front office supervisor, and vendor liaison Margaret Moore, the electronic archiving system at the 148-bed Carson-Tahoe Hospital in Carson City, Nev, has been in place for about 2 years. Even in that short time, they say, the system has overflowed its capacity and is about to undergo a major upgrade. The situation at Carson-Tahoe is illustrative of a major concern for archivists: No electronic archive is an island.
As currently configured, according to Weber and Moore, the Carson-Tahoe electronic archive is limited to cross-sectional studies only. All plain film studies are still being handled only on film. Estimating that the hospital and a single outpatient clinic do about 50,000 examinations per year, Weber says only about 50% of those are archived electronically. The electronic archive is run through the hospital’s PACS, which was purchased for about $500,000. It included a DICOM-compliant server and a CD (compact disk) jukebox that holds and can access studies on 600 disks. Each CD can hold about 150 patient examinations, which the system can call up by examination. About 6 months ago, the jukebox, which cost about $35,000 when new, reached its capacity and the oldest CDs are now being stored in racks next to the jukebox. In addition to the outlay for the original PACS, the hospital has a service contract with its vendor, which, according to Weber, includes an annual fee of roughly 10% of what the PACS cost.
The PACS hard drive has enough storage capacity for about 2 weeks’ worth of imaging. Images older than 2 weeks must be moved to CDs in the jukebox.
Both the PACS hard drive storage and the CDs in the jukebox are accessible through the hospital’s local area network (LAN), which is hardwired into the hospital and the outpatient clinic. The LAN is accessible through the hospital’s array of PCs as well as at a handful of workstations and at two reading rooms set up for the seven radiologists on staff. Any hospital clinician with clearance for a given patient can access the PACS to see full-fidelity images and in the bargain receive an audio report on the study as dictated into the system by the radiologist doing the read. The system carries no text, only the images and the voice tape. According to Moore, the electronic archive is extremely “user friendly” and has been well received and consistently used by the radiology department.
That is the good news. The bad news is that the system remains cumbersome and has not been well received by many of the hospital’s doctors, too many of whom have left standing orders that they want (and are getting) all of their images on film. Weber says, for instance, that all the OR doctors are demanding and getting film images.
Moreover, the hospital is finding that attempts to send images outside the LAN are unreliable, for reasons that remain unclear. “We’re having to send in a may or may not make it mode,” Weber says. Then too, the hospital must initiate the sending process through its modems, and a single MR study can take 45 minutes to transmit. Referring physicians cannot tap into the LAN from outside to see studies. For these reasons, referring doctors for the most part are still asking for film or hard-copy prints from film.
Another problem for Carson-Tahoe is that the transfer of data from the PACS hard drive to the CDs in the jukebox must be initiated by hand. The CDs must be burned from the hard drive, says Moore, a nightly process that can take as much as 4 hours. While the CDs are being burned, the jukebox is down. If there is an emergency when a comparative study must be obtained from the jukebox, then the burning process must be shut down. Add to this the half hour or so that must be spent each day fetching an estimated four to eight studies from CDs in the overflow trays outside the jukebox, and it is easy to see why Carson-Tahoe is about to give its vendor another $250,000, roughly half of its PACS original cost, for an upgrade of its PACS and archive.
According to Weber and Moore, that upgrade, scheduled for mid-to-late summer, will consist of two major changes. First, the hospital will install a Web browser to allow referring physicians to call up their patients’ images over the Internet. Second, the CD jukebox will be replaced by a physically smaller jukebox holding 600 DVDs. Moore estimates that each DVD will hold 30 times as much as a CD. Moore and Weber say they do not think the DVD jukebox will ever overflow since it will hold studies long enough that normal purging will leave room for incoming studies.
Moore says migration of the data from CDs to DVDs will be handled by the vendor. She is not sure how it will work. After the migration, all files in the long-term jukebox archive will be on DVDs. With the DVD jukebox will come the automatic storing of data from the PACS hard drive to the jukebox. The nightly burning will be a thing of the past.
Even with the upgrade, says Moore, the hospital will continue to film its conventional radiographic studies. The cost of converting the plain film studies to a digital format and putting them into the DVD jukebox is more than the hospital can afford just now, Moore says. When the upgrade is completed, a big part of Moore’s job will be to show the hospital’s staff doctors and its referring physicians how to use the electronic archive and to convince them that it is more convenient and indeed more user friendly than waiting for film.
The Health System
The latest buzzword in electronic archiving is enterprise-wide, meaning that the image archiving needs of all departments in an institution can be accommodated with a single archiving solution, whether it involves multiple archives or a single, central archive. Radiology, which led the way with most PACS and archive system developments and installations because it was the simplest and most logical department to digitize, is no longer in the driver’s seat, or, if in the driver’s seat, may have a codriver. The typical radiological examination takes about 25 megabytes of hard drive to store. A cardiology examination takes 10 times that. But both departments’ storage needs can be shared.
At Brigham and Women’s Hospital in Boston, a merger with Massachusetts General Hospital has resulted in the Partners Healthcare network of about a half-dozen institutions where the radiological examinations alone top 400,000 annually. Brigham, a 702-bed hospital, is only one element in a new archiving effort that is aimed at combining the archiving needs (as well as upgrading the PACS through which the archive will run) for the whole system, including the radiology, cardiology, pathology, and anesthesiology departments.
According to Bill Hanlon, MSc, who is director of research and development in the radiology department at Brigham, the goal now is to jointly archive all DICOM images throughout the system. Brigham is about to send out RFPs (requests for proposals) to storage vendors to accomplish this goal. Failing a suitable solution through a vendor, says Hanlon, the Partners Information Technology Department, which has overseen the installation and networking of approximately 30,000 PCs for the Partners system, could be called on to construct its own archiving system. It is not ground that Brigham wants to break. “We’re in the health care delivery business. We are not storage experts, and we don’t want to become storage experts,” Hanlon says. “We’re looking to outsource unless it is far more expensive than building our own. My CFO is not going to pay $5 per study if we can do it for $2 or $3 per study. He is not going to spend a million when it can be done for a half million. We’re doing that analysis and running that study.”
For now, Brigham is storing its online radiological images on about a terabyte of PACS on demand space, about a 6-month capacity. For offline storage, it has a 20-terabyte combined MOD (magneto-optical disk) and DLT 7000 (digital linear tape) system, which has become half full in the past 2 1/2 years. Increasing imaging demand gives less than another 2 1/2 years until the system is full, Hanlon says, adding, “We hope to have both systems replaced by this time next year.” The DLT particularly has been difficult, Hanlon says. The tape is slow and high maintenance. It has to be re-tensioned fairly often. Overnight prefetching of images for the next day’s round of radiological patients is routine. Like many, Brigham’s IT team has been shocked at the level of activity its long-term storage experiences. “Our archive every night gets 600 different requests for prefetch. Maybe a third of our tapes get read. We were surprised-very surprised,” says Hanlon.
Hanlon says virtually all imaging at Brigham still gets filmed as a redundancy. But the hospital does not want to keep that up except for legal requirements for mammography.
Hanlon explains how a clinician (an orthopedist, for instance) can use today’s archiving system: “He can find a clinical review station and call the image up on the PACS,” Hanlon says. “He can walk down to radiology-or he can get it over the Web, if it is a CT or MR image. Whatever is fastest at the moment is the preferred methodology.”
But not all the Partners clinics have review stations with access to PACS, and its Web-based report system is just for CT and MR images. From a clinical review station a query can be made for all images on the PACS, but it may take 10 minutes for the images to arrive, Hanlon says. Brigham wants faster and better delivery with ad hoc queries available to all clinicians. It wants overnight pre-fetching automatically for all clinical departments, not just for radiology. “An orthopedist is not on automatic prefetch, but we’ll have that someday,” Hanlon vows.
Conclusion
From the foregoing it can be seen that there are many choices for the would-be electronic archivist, and the future can be expected to unveil further choices. In summary, one point is worth stressing.
Like the buffalo herds of old, today’s herds of electronically stored long-term data must make periodic migrations. Migration is needed when new technology develops that is superior and cheaper. Like the migrations of buffalo, migrations of data (which take place mostly at night) face hazards. Data can be lost or snarled in transit. Data migrations are not cheap either.
Anyone moving to an electronic archive should prepare for the expense and headache of migration. Wherever the electronic archiving journey takes the institution, it is well advised to take the time to chart the course carefully prior to leaving.
George Wiley is a contributing writer for Decisions in Axis Imaging News.
