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Integrating PACS Power

November 1, 1998
by Edmund X. DeJesus
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While the technology side of PACS is strong, it’s the way you implement your PACS--and especially the way you integrate your PACS with your hospital and radiology information system--that makes all the difference.

We have the technology. Finally, the hardware and software pieces for a picture archiving and communication system (PACS) are falling into place. Mainstream technologies are making a PACS more doable than ever before. But it’s when you integrate your PACS with your hospital or radiology information system (HIS or RIS) that you start seeing the most interesting results. The payback comes both in better patient care and in the bottom line.

You name the technology--either available now or in the near future--and you can use it in your PACS. For example, the latest hard drives--faster, roomier, smaller and cheaper--make a lot of sense as arrays for storing recent multi-megabyte medical image files locally. Inexpensive and plentiful RAM--standard on many platforms--simplifies manipulating those images on each workstation. Even off-the-shelf monitors are getting bigger, brighter and sharper, giving physicians a better look at the pictures.

Long-term storage of images--even on film--has always been a problem of not enough space and not fast enough access. That is changing with networked optical disk jukeboxes that can hold many terabytes (thousands of gigabytes or millions of megabytes). You’ll probably be archiving older images on digital linear-tape jukeboxes that offer even greater capacity. Some facilities opt for pressing their own CDs: small, cheap, non-degrading and at least 600 MB each. Throw in automatic lossless image compression (which guarantees that you get your original image back again) and you can easily double all these capacities.

Multiprocessor servers are just right for handling big image throughput fast. There are so many good ones available, you can even be choosy about platforms that match your other hardware.

Moving those images around from servers to workstations requires a heavy-duty network. Luckily, that’s exactly the standard these days. Run-of-the-mill 100 Mbps fast Ethernet may suffice for your backbone (imaging server, plus storage, plus archives), but you really should consider something on the order of switched high-speed 622 Mbps ATM, Fiber Channel, or a comparable alternative. (Most observers regard gigabit Ethernet as not quite ready for prime time--yet. ATM has the advantage of allowing quality of service features that can prioritize certain traffic--like images bound for the emergency room.) On the image acquisition end, a stressed PACS might be pushing about 2 GB per hour--per imager--and you want to be able to handle all that traffic: something on the order of switched 10 Mbps Ethernet or faster makes sense. On the diagnostic viewing end--where the radiologist, cardiologist or other specialist actually makes the diagnosis--you want at least 100 Mbps Ethernet. These are time-intensive and critical applications, and need the bandwidth. Naturally, you’ll want to make sure your hubs and routers are up to speed, too.

Standards are playing a key role in simplifying the PACS picture. For example, DICOM (Digital Imaging and Communications in Medicine) is the standard for connecting medical imaging equipment with networks. Version 3.0 of the DICOM standard is especially flexible. It covers existing imaging modes and allows for the definition of new modes as technology advances. Middleware standards like CORBA are already proving useful in linking legacy imaging systems. William Langdon, executive director with Superior Consultant Company, Southfield, Mich., notes that open systems and standards keep vendors competitive.

The case for integration
While the technology side of the picture is rosy, it is the way you implement your PACS--and especially the way you integrate your PACS with your hospital or radiology information system--that is making all the difference these days. Part of the reason has to do with the hefty price tag for your PACS: from the hundreds of thousands to millions of dollars. That can be tough to justify if all your PACS does is help a handful of radiologists. Another part of the reason has to do with that ubiquitous partner of current health services, managed care. You have to do the right things at the right time in the right way--or you don’t get paid. Your PACS--by itself--can’t handle these conditions.

PACS is not just for radiology anymore. Sure, it can handle X-rays and even computed radiography for special effects, but a well-integrated PACS can also deal with ultrasound, fluoroscopy, computed tomography, magnetic resonance, nuclear medicine and other image modalities. In fact, one shrewd move is to have an image server physically close to each of these imaging areas: that’s probably where most of the diagnostic viewing is going to happen also, and you’ll save the rest of the network from unnecessary traffic.