DR pathfinder adds flat panel to CCD technology

Swissray International cut its teeth on digital radiography using charge-coupled device technology. Since receiving clearance from the FDA to market its first DR system in 1997, the company had been selling CCD systems exclusively.

That changed at the 2005 RSNA meeting, when the company introduced a flat-panel DR line of products. Swissray launched the ddRFormula C-arm system for general radiography and the ddRCombi Trauma overhead tube suspension system for the emergency department. Both use amorphous silicon cesium iodide thin-film transistor technology.

The move to flat-panel products does not mean Swissray is abandoning its CCD offerings. It is merely reacting to a demanding hospital marketplace.

"It became apparent to us that some customers had a preference FOR flat-panel detectors," said John Monahan, vice president of corporate accounts. "We didn't want to be shut out of certain fields, so we made a strategic decision to add flat-panel technology to our product portfolio."

The customers most adamant about flat panel were hospitals with strong physics departments. Monahan believes physicists have a bias toward flat-panel technology over CCD. He does not, however, see a distinction between the technologies in terms of clinical image quality.

"If you were to take images from a flat panel and images from a CCD, more than 90% of the time, a radiologist wouldn't see much of a difference," Monahan said.

Swissray's flat-panel systems incorporate the Trixell Pixium 4600 detector, which is suitable for chest, abdominal, extremity, and skeletal imaging. The detector has a 143-micron pixel pitch and nine million-pixel resolution. Because the detector is small and lightweight (it measures 535 x 490 x 45.5 mm and weighs 17.2 kg), Swissray was able to use lightweight motors and keep the ddRFormula and ddRCombi Trauma systems compact in size.

To differentiate its flat-panel systems from others that use a Trixell detector, Swissray developed the 3P Panel Protection Program. The systems place the detector in a floating frame shock absorber and include an energy dampening mechanism to absorb and dissipate impact energy before it reaches the panel. The systems also have an infrared sensor that overrides the user to slow down and stop the detector if there is an object in its path. A carbon fiber in the detector absorbs x-rays to lower the dose to patients.

The ddRFormula and ddRCombi Trauma systems have been designed for versatility. A ddRFormula Plus unit has motorized x-ray tube rotation to allow off-detector imaging on cassette media for patients who cannot be transferred to an imaging table in an emergency situation. In addition to the ddRCombi Trauma system, which has a fixed table with an elevating base and four-way floating top, Swissray offers the ddRCombi Plus FP, a floor-mounted positioning device and a vertically motorized synchronized ceiling suspension system for performing general DR examinations on patients in recumbent, seated, or upright positions.

As part of special development agreements, the first ddRFormula system was installed at an institution in Chicago. The first ddRCombi Trauma system was installed at a clinical site in Atlanta. Production models of flat-panel products will be available for delivery in April, Monahan said.

The flat-panel products join Swissray's CCD-based C-arm units - ddRChest, ddRModulaire, and ddRModulaire Plus - and an overhead tube suspension ddRCombi Plus CCD unit with a fixed floor CCD detector.

Swissray is continuing to support CCD technology as a price-sensitive alternative that delivers high-quality imaging. There is a significant price difference between the flat panel and the CCD but not much difference in spatial resolution, Monahan said. CCD technology is capable of achieving 3.2 line pair per millimeter resolution, while a flat panel is capable of 3.5 line pair per millimeter.

"The only time we believe this difference has any significance is in imaging neonates, infants, and toddlers, when the bones are not really formed. The little extra imaging (performance) is a benefit in those cases," Monahan said.

Over the last eight years, Swissray has sold CCD units to more than 500 customers. Since more than 30% have been repeat buyers, they must be satisfied with the imaging capability of the CCD, he said.

"I do see the CCD line continuing," Monahan said. "However, the market will dictate."