CHICAGO - The high cost of digital radiography systems is undoubtedly a major factor limiting the proliferation of the technology. But what if a company could offer the benefits of DR at a cost approaching that of computed radiography systems?
An Israeli startup called Edge Medical Devices hopes to provide the answer to that question. This week in Chicago, the firm is unveiling its Quix family of amorphous selenium-based DR detectors, which are distinguished by the use of what Edge calls scanned matrix array readout technology (SMART).
With the SMART detector, Edge has avoided the use of the photodiodes or thin-film transistor arrays traditionally employed by other flat-panel detectors to provide image readout. Instead, after the x-ray exposure, a line scanner sweeps across the detector, transforming the signal charge to an image in 1.8 seconds, according to Edge president Robert Sohval, a medical imaging veteran who has served stints at companies such as Elscint Medical Systems, SmartLight, and TransScan.
"The detector structure has a set of parallel lines and doesn’t have the complex lithography that’s required of typical active-matrix arrays," Sohval said.
The detector is monolithic, allowing the firm to avoid the complications of tiling together subdetector units, he said. And with a size of 17 x 17 inches, the company believes it can support all x-ray applications without detector rotation, Sohval said.
Edge also points to the image quality and efficiency of its detector. It is generating 127-micron images, with a fill factor, or geometric efficiency, of nearly 100%, Sohval said.
"On an active-matrix array detector, the space occupied by the detector elements has a typical fill factor of between 60% and 85%, losing 15% to 40% of the dose," Sohval said. "In our case, we have virtually zero dead space, with a nearly 100% fill factor for the highest dose efficiency."
But perhaps most importantly, the SMART technology is much cheaper to produce than active-matrix array detectors, according to Edge, which also maintains sales and marketing operations in Hackensack, NJ. An active-matrix array detector could have 10 million or 12 million active elements, all of which must be individually checked in the manufacturing process to avoid dead pixels or dead pixel clusters, Sohval said. As such, it’s very complex and costly to build a high-yield, large-area, 17 x 17-inch active-array detector, he said.
In addition, Edge believes that its detectors will also offer durability advantages over other DR approaches. With traditional DR flat-panel detectors, the active-matrix arrays lie on the surface of the detector, exposing them to repeated radiation exposure and damage that can lead to image degradation and the possible need for replacement, he said. Because there are no active elements on the surface of the SMART detector, it is not susceptible to radiation damage, Sohval said.
Thanks to the reduction in cost for the SMART detectors, the vendor believes that DR technology is now feasible for environments such as private imaging centers and community hospitals.
"Our detectors set a new price point that will allow what we would call twin-detector DR suites, including a dedicated detector in the chest stand and a dedicated detector in the table," he said. "They could also share a single operator console for both detectors."
Edge plans to sell its detectors as retrofit kits for existing radiographic equipment for both table and chest units, and to OEMs for integration into new DR systems, Sohval said. The detector’s thin profile allows it to directly replace the film-screen bucky in a standard chest stand or radiographic table with only minor modifications, according to Sohval.
"You simply remove the film bucky, attach brackets to the digital bucky, and then just slide the detector in," Sohval said. "It should be a straightforward upgrade, and the cost per room will be comparable to CR."
Edge will be submitting its 510(k) application to the Food and Drug Administration in the first quarter of 2001, and hopes to begin shipments in the second quarter. Final pricing has not yet been determined, but the detectors will likely have a price range similar to mid-range CR systems, Sohval said. In future plans, Edge hopes to apply its SMART technology to digital mammography and portable DR applications, Sohval said.
By Erik L. Ridley
AuntMinnie.com staff writer
November 27, 2000
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