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June 19, 2006

CR vs. DR — The Digital X-ray Decision
By Beth W. Orenstein
Radiology Today
Vol. 7 No. 12 P. 10

Some see lines between CR and DR blurring. Some see the decision based on your facility’s specific needs. Others see them as teammates.

These days, medical imaging facilities, whether stand-alone or hospital-based, are under tremendous pressure to go digital to improve efficiency, reduce costs, and improve safety.

Facilities that want to take their x-ray departments from analog to digital basically have two options: computed radiography (CR) and direct digital radiography (DR).

“Both acquire an image digitally and provide the digital image back to the user,” says Penny Maier, national marketing manager for Fujifilm Medical System USA’s digital x-ray.

CR has been around longer than DR—roughly 25 years vs. eight years, says Todd R. Minnigh, director of marketing, Americas, for Kodak’s Health Group. The Eastman Kodak Company patented the storage phosphor imaging plate technology used in CR in 1975.

When DR became more readily available, many people in healthcare predicted it would quickly overtake CR. However, that has yet to happen. Thanks to advancements in both technologies, they are continuing to coexist and doing so quite nicely, most vendors say.

Peaceful Coexistence?
Vendors believe the two technologies coexist because each still has its distinct advantages, and which is best for a hospital or imaging facility depends largely on its size, workload, and infrastructure.

Cost continues to be one of the major decision makers when choosing to convert from film to CR or DR. As with most technology after it has been around awhile, the cost of DR is coming down, Minnigh says.

However, says Kuldip Ahluwalia, vice president of sales and marketing for Alara Inc., based in Fremont, Calif., DR is still far more expensive than CR. The issue is not only the equipment itself but also ancillary costs such as installation and warranty.

DR typically requires purchasing entirely new x-ray equipment, and new x-ray equipment almost always requires remodeling of the radiography room, which can get pricey. “The remodeling, permitting, and installation costs can add $30,000 to $50,000 to the project, and I’m being conservative,” Ahluwalia says. “In hospital environments, remodeling costs may be closer to $200,000, depending on the existing infrastructure, regulatory requirements, and back-up clinical needs during the remodel. Half of the equation is the equipment, the other half is the construction and installation part of the task.”

Because of the equipment and infrastructure requirements, a DR system can be three to five times the cost of CR. “The list price on a high-quality CR system today can be as low as in the $70,000 range, while for a DR, you’re typically looking at $350,000-plus with the new equipment,” Maier says.

Cost Differences
Even with new mid-tier entrants such as Vidar (Vision 4000), the price of DR systems can easily exceed $200,000. That’s why, if a facility is building a new or replacing an existing x-ray room, it’s likely to choose DR, Minnigh says. However, he says, if it wants to convert from film to digital to be able to electronically transmit images or get a better handle on lost films or repeats, it will likely opt for CR. “CR still is the most cost-effective way to retrofit your department and make it digital,” he says.

Some argue that the productivity gains from DR can offset its higher cost. While the gap in acquisition time between DR and CR is closing, DR is still faster. DR saves time because technologists do not have to handle and process cassettes as with CR. Also with DR, the image is seen immediately. On most systems, preliminary images are available within seconds and full resolution images in 30 to 45 seconds.

“With Fuji’s DR system, you’ll start to see an image in about two seconds and it’s finished in seven seconds,” Maier says. “It’s very fast.” In comparison, with a Fuji CR device, it takes approximately 20 seconds to begin to see an image.

Because it takes less time to acquire the image with DR, theoretically, facilities could more quickly process patients in DR rooms. “If you were doing the same exam over and over again—like a chest x-ray—you would blow away productivity with DR vs. a cassette-based system,” says Ted Ciona, product manager for Agfa Healthcare USA in Ridgefield Park, N.J. The DR can display the image and be ready for its next acquisition in approximately 10 seconds.

However, Ciona says, radiography rooms are not always used repeatedly for the same exam. Once the technologist has to adjust the equipment for different exams and reposition patients, the DR detector loses some of its acquisition time advantage.

Also, Ciona says, the acquisition time has been reduced with some of the newer CR systems such as Agfa’s DX-S. With older CR readers, it would take roughly one minute to get an image. “Now our CR systems can display images in about 10 seconds, erase the plate, and give it back to the technologist in the same time as a DR device.”

Throughput
Sally Grady, director of imaging services for Florida Hospital Celebration Health, an eight-year-old hospital near Disney World in central Florida, has found that with its new Agfa DX-S system, her department can be as productive as it could be if it used DR. “I’ve always believed that if you set up your systems appropriately and productively. DR is not that much more productive than CR. With this new generation of CR, I believe that’s even truer,” she says.

A technologist was able to do 54 exams in an eight-hour shift with one DX-S, Grady says.

Arne Helbig, international marketing manager for general x-ray for Philips Medical Systems, based in Hamburg, Germany, agrees that a smaller institution with a lower throughput would not benefit as much from DR because of its higher up-front and installation costs. “If you’re not dependent on the speed that DR can provide, if you do only 15, 20, 25 patients a day in that room, there is no point in investing in DR because you won’t be able to achieve a decent return on investment there,” he says.

Improvements in CR’s design also have made it more competitive with DR. For example, Fuji’s CR systems have shrunk to the point where they can now fit inside the exam room or between two exam rooms, Maier says. “Having the CR system right there increases productivity because it minimizes the amount of walking the technologist needs to do to process the cassette,” she says.

However, David Widmann, general manager of GE Healthcare’s radiography and radiography/fluoroscopy business based in Waukesha, Wis., says that with DR, the facility may need fewer rooms, which would offset initial investment costs. “DR has the advantage that it’s so fast that you can reduce the number of pieces of physical equipment in your institution,” he says. “So economically, the workflow and speed advantages of DR will be demonstrated as departments replace equipment and embrace digitalization.”

Another issue is flexibility. DR systems have become more flexible. Canon introduced portable DR in 2001. DR detectors can be mounted on movable columns that can be positioned in three dimensions. However, DR is still more cumbersome than CR. “DR can be unwieldy,” Ahluwalia says. “You have to position the patient over the device. With CR, you essentially have a stand-alone cassette, so a patient could be in a wheelchair or in a bed. With CR, you can bring a portable unit, shoot the image and process the information in the CR reader. With DR you can’t do that yet.”

Fixed vs. Cassette
Ciona says a fixed DR device just wouldn’t work in some situations. “If you’re in the emergency room or trauma unit and you have to do an occasional exam where the patient can’t get out of a wheelchair or off a gurney, how do you position it with a fixed DR detector without a lot of grief? It’s a lot harder to position the patient. With cassettes, you just slip them under the patient.”

CR is also a stand-alone device that can be positioned anywhere without stringing data and power cords around the patient, Ahluwalia says. “Even with portable DR systems, you always have data and power cables between the collection plates and the electronics, and there are a lot of challenges of having electronic and data cords around sick patients.”

DR collection plates or CR cassettes can break in challenging environments, but CR cassettes can be easily replaced for $1,000 compared with more than $50,000 for DR collection plates, Ahluwalia says.

The ruggedness and greater portability of CR is another reason some vendors believe CR and DR will continue to coexist for quite sometime.

Going all DR also raises the issue of reliability. “If you have two or three CR readers, you have automatic redundancy because you can just use another reader,” says Helbig. “Whereas if the DR detector fails, that room is closed off and you have to wait until service comes in.”

Backup Needs
Ahluwalia agrees that CR provides valuable and necessary backup. “Say a facility has six conventional x-ray rooms, shuts them down, and builds a new facility. Instead of six conventional rooms, it decides to build three DR rooms because of the increased throughput,” he says. “But what happens if one of those rooms goes down? Your throughput goes down by 33%, too.”

Ahluwalia believes his company is seeing more and more inquiries for its CRystalView CR system as an adjunct to DR. “People who are buying DR equipment are saying, ‘Hey, we want your CR equipment as well.’ That’s especially true because CRystalView is compact and it’s very, very portable.”

However, Widmann argues that redundancy or reliability is not an issue with DR. “X-ray rooms are pretty reliable, so we don’t see that as an issue at all at GE,” he says. “Indeed, industrywide, the reliability is pretty good in the x-ray room.”

Minnigh doesn’t see redundancy with DR as an issue, either, unless the facility has only one room and one detector. “That would be a limiting scenario,” he says. “But in most cases, you have more than one room and, if room 1 is down, you can always go to room 2. Having all DR isn’t terrible.”

Yet another issue when choosing CR and/or DR is image quality. Analog or film is still the gold standard, Ahluwalia says. “CR and DR are always going to give you a little less spatial resolution.” DR probably offers a little better overall image quality than CR for the same dose. However, he says, newer CR systems offer improved image quality along with the advantages of wide dynamic range associated with digital imaging.

Ciona says Agfa’s patented needle-based storage phosphorus cassette technology clearly surpasses the quality of images from lower-end DRs that use charge-coupled devices.

Grady has found that with Agfa’s MUSICA2 image processing software, the quality of the image is superb. “It’s superior to anything I’ve ever seen off DR or other CRs,” she says. “It’s to the point where I can do a hand x-ray and if the lady has fake fingernails I can see them. You can do a foot x-ray and see people’s toenails. The level of detail you get from MUSICA2 is just amazing.”

While image quality with CR and DR may not be as great as with film, the advantage to the digital technologies is that the images can be postprocessed.

“You can do just about everything with those images once they’re digital,” Helbig says. “You can send them around, postprocess them, change the processing parameters so you see different things in the images, have different image impressions.”

Postprocessing
Widmann believes DR has the advantage over CR when it comes to postprocessing. “A CR image by definition is very much like a film image. It’s static vs. a DR image, which is dynamic,” he says. “And, although you can manipulate the image in CR, you will face limitations on how CR data is used to benefit clinical outcomes utilizing advanced applications such as dual energy, tomosynthesis, and automated image pasting.”

Maier disagrees. “A CR image is a digital image, just like DR,” she says. The downside to images acquired on many DR systems is that it’s a relatively new technology and vendors are still refining the processing algorithms, which can decrease technologist efficiency and compromise image quality, she says. “Because Fuji is able to apply its sophisticated set of image processing tools to images acquired by both our CR and DR, the first-up image display is optimal regardless of the acquisition location, so radiologists do not face interpretation issues due to inconsistent quality.”

DR also has the advantage that the study can be done with lower radiation doses than CR systems. That’s a major advantage given that radiation is cumulative over a lifetime, the vendors agree.

Looking Ahead
Widmann thinks DR will eventually be the technology everyone chooses. “DR is only [eight] years old,” he says, “and in just [eight] years, the technology has changed so much. You can only image what’s going to happen in the next five to six years. It’s hard to predict the future, but it seems that the CR technology has matured and, at the end of the day, doesn’t have the same kind of advantages that DR has. I believe that workflow, dose, and image quality will come together and be the performance advantages that will drive customers to DR as a solution.”

Ahluwalia also believes DR will become more prevalent as prices are lowered even more and its quality and ease of use continues to vastly improve. Still, he believes CR will continue its presence in the marketplace and the two will continue to coexist for quite sometime.

Eventually, Ahluwalia thinks it is film that will totally disappear. He says, “I think there is a time in the future where we will all be able to say, ‘Film has gone by the wayside,’ but I think that’s at least a generation away.”

— Beth W. Orenstein, a freelance health writer who lives in Northampton, Pa., is a regular contributor to Radiology Today.