Battle of the detectors defines future of DR market

Debate grows over which technology will capture the imagination of buyers and how big the market will be

BY GREG FREIHERR

Advanced applications such as dual energy subtraction could provide a clinical reason for choosing digital over conventional radiography by providing better image quality. (Provided by GE Medical Systems)

Vendors of digital radiography (DR) systems are preparing the launch of a major marketing effort before year's end. Industry sources say that GE, Siemens, and Philips are now secure in the belief that quality problems at their flat-panel production plants have been worked out and they can meet demand for digital systems. In addition to the usual glowing talk about advanced technology and touting of image quality, vendors hope to document productivity gains achieved with their digital systems.

"More numbers, less hand waving," said Jeff Levett, product marketing manger for Siemens x-ray.

Competitors will be offering a range of technologies including amorphous silicon and selenium-based flat panels and detectors made from charge-coupled devices (CCD). As of August, the major proponent of CCD-based detectors, Swissray, had made 78 sales of digital x-ray products: 64 already delivered and 14 on back order. Hologic, the leading developer of selenium-based systems created at its Direct Radiography Corp. (DRC) subsidiary, had delivered more than 30 digital x-ray systems with more than 20 on back order, not including the 70 or more detectors that had been shipped to OEMs for use in privately labeled products. Canon Medical Systems had installed about 80 digital systems worldwide, 20 of them operating at institutions in the U.S. GE Medical Systems, the leading vendor of amorphous silicon-based systems, had sold about 70 of its Revolution XQ/i, a dedicated digital chest system. The release of the Revolution XR/d, a dual detector that allows general radiography on a table and chest exams with a wall-hung detector, is expected to expand GE's base in the months ahead.

"This is the full digital solution," said Renaud Maloberti, GE global product manager for digital radiography. "We have seen tremendous activity from customers at shows we've been attending, which indicates that the market for digital rad is going to be huge."

Feeding the demand for GE x-ray systems are two detector production lines. Large panels for the radiographic products are being built at GE's ally, Perkin Elmer in Santa Clara, CA. The smaller plates for cardiac and mammography scanners are being made at the GE plant in Schenectady, NY.

Similarly, production of amorphous silicon plates is gearing up at Trixell, which supplies Philips and Siemens. Underscoring its commitment to digital x-ray and foreshadowing the RSNA meeting in November, Trixell staged a media event at its production facility in Moirans, France, on Sept. 27. The event highlighted production with a tour of the facility. Testimonials from physicians at key European luminary sites underscored the success of production line plates at delivering high-quality images at low x-ray doses.

SALES PREDICTIONS VARY

The table is set for a feast of industrial self-congratulation. Across the board, executives are calling for dramatically rising sales.

"There is very real potential for the technology to take off," said Rex Harmon, vice president of global marketing for Swissray. "Five years ago it wasn't ready and the (PACS) networks weren't ready, but they are now."

How dramatic sales growth will be, however, is open for debate. Consensus among industry sources indicates that annual sales of DR units will probably be only a few hundred within the next several years. The most optimistic predictions call for an annual sales rate of just 600 units in 2003. Contributing to this number will be dedicated digital chest units. These could top out at around 100 and then begin to fall, however, as general-purpose rooms capable of doing all radiographic exams begin to reduce the need for dedicated chest units.

This transition is already apparent in GE's clinical expansion of the Revolution XQ/i, which was initially designed as a dedicated upright chest unit but is now being loaded with algorithms that support cervical spine and abdominal work. The trend away from dedicated chest units is underscored further by GE's decision to match its most recent digital model—the general-purpose digital x-ray table Revolution XR/d—with a wall-mounted flat panel for chest exams. Siemens' Vertix FD employs an overhead tube stand that can be configured with detectors built into a table as well as a wall stand. Canon Medical Systems offers its CXDI-22, a digital detector that can be built into upright and table systems, using a universal stand.

Other vendors have fielded even more versatile digital products capable of handling both chest and general radiographic procedures. Swissray's ddRCombi and ddRMulti-System are two. The Combi works with a ceiling-suspended tube stand, operating as an upright for chest exams, then pivoting into a horizontal position to slide under a patient exam table for general radiographic applications. The Multi-System has the x-ray tube and detector mounted on opposite ends of a C-arm that can be rotated into position for upright as well as recumbent exams. Because the solid-state detector is the most expensive component of a digital x-ray system, using a single one for both types of studies can cut more than $100,000 from the purchase price.

The need for new systems may be cut even more through the retrofit of existing ones. At least six companies now offer or are developing such retrofits: Hologic's DRC, Canon, InfiMed, Cares Built, Rogan Medical, and Imaging Dynamics. Each of these companies offers detector matchups to existing x-ray generators that promise to protect a facility's existing investment in conventional systems.

Although Canon's CXDI-22 can be integrated into a brand-new product, 18 of the 20 digital systems installed in the U.S. have been retrofits. Marketing director Neo Imai believes digital x-ray will catch on only if companies try to conserve equipment in the installed base.

Imai notes that most turnkey general radiography systems commonly cost the end user more than $400,000. Systems with two flat panels, one in the table and another hung on the wall, can reach $600,000. A retrofit from Canon costs the end user just $225,000, he said.

DIGITAL DREAMERS

Some vendors still speak of a billion- dollar-a-year world market, even though this would require the sale of at least 2000 units annually, which is three to four times the number that most industry executives publicly believe is realistic. The disconnect between hyperbole and reality may be a holdover from the time when sales expectations were tied to a one-to-one replacement of the installed base of x-ray equipment.

Global estimates that some 200,000 radiographic units are now in place spurred predictions that worldwide unit sales might top several thousand per year, the pace at which just 50% of these systems would be replaced over a 10-year period. Early experiences with digital systems indicate, however, that one digital room, properly managed, can replace two or three film-based rooms. Digital images can be reviewed immediately and the patient sent home, allowing 10 to 15 exams per hour compared with five or six using filmbased systems.

Such efficiencies have cut into the number of rooms that need to be replaced. Another stumbling block has been the slow adoption of PACS, which is viewed as an enabling technology for DR. Observers of the PACS industry say this market has begun to come to life. The entry of large vendors into Web-based application service provider networks that transmit and store digital images could provide an additional boost.

The customer interested in digital x-ray has a wide selection from which to choose. Philips was among the first to offer a digital dedicated chest unit, introducing Thoravision in the early 1990s. The system, which remains in the company's product line, uses a selenium drum to record data. Philips also offers the Digital Diagnost, which is essentially the company's general-purpose radiographic system, Bucky TH, outfitted with a Trixell-built detector rather than a film bucky.

Siemens has three digital systems. Its Vertix FD, allowing both chest and general radiographic work, is joined by two dedicated products, the Thorax FD upright chest product and the Multix FD table system.

Canon offers a dedicated chest unit, CXDI-11, which is based on the same amorphous silicon detector used in its multipurpose CXDI-22 retrofit system. The upright system is also being supplied to Agfa for sale under that company's label as the DR Thorax.

The main proponent of selenium-based flat panels is Hologic. Through its DRC subsidiary, the company is selling two systems, Epex and Radex. Epex is a high-performance general radiography system. Radex is a lower cost general radiography option intended for the outpatient department.

The company also sells its detector as a retrofit for existing film-based systems and to OEMs for use in their privately labeled products. One of the best known of these OEMs is Kodak, which is working with Analogic to integrate the detector into Kodak's DR 5000 dedicated chest system, general radiography product DR 9000, and retrofit system DR 7000. The oldest OEM is Fischer Imaging, which offers the Traumex general-purpose table system.

Swissray offers not only its ddRCombi and ddRMulti-System but the ddRChest, which is dedicated to upright exams. Like the other two, this system is based on CCD technology. The floor-mounted C-arm device is optimized to examine seated and upright patients.

Trex Medical's digital chest unit, the 4000M, is also based on CCD chips. The digital detector is supplied by Advanced Instrument Development, which licenses the technology from the Finnish firm Imix. Nucletron/Oldelft offers two digital chest units, Digidelca-C and -M, based on CCDs. Wuestec Medical, in collaboration with the Korean electronics firm Samsung, has created a CCD-based detector for its general radiography system, the DX-1480. A newcomer to the digital industry is Canada-based Imaging Dynamics, which has developed a CCD detector called Xplorer 1000 that is designed primarily as a retrofit for installed analog systems.

Cares Built is taking a different approach to the technology. Its digital system, called Clarity 7000, is built around complementary metal-oxide semiconductor (CMOS) technology. CMOS is similar to CCD technology—detectors are composed of individual chips that can be assembled into plates of a specific size. CMOS detectors can be used as a retrofit for bucky-style x-ray systems, or they can serve as the backbone for the company's FleX-Ray line of digital x-ray systems. These include table-based general radiography products, as well as systems featuring tomography and wall-hung buckys. Rogan Medical Systems is also developing a CMOS-based detector to address the retrofit market.

DUELING DETECTORS

Sure to complicate matters is the debate over which technology is best. Digital radiography breaks into different camps. One is computed radiography (CR), which is dependent on the use of phosphor-based plates. Once exposed to x-rays, these plates are put in a CR reader and energized with a laser, causing light flashes that correspond to the energy imparted by the x-rays that struck the plate. These flashes are then recorded, turned into electrical impulses, and translated into electronic images.

Fuji Medical Systems U.S.A. offers products that read individual plates designed to fit into radiographic tables and wall-mounted buckys. Critics of CR charge that readers hardly reduce labor, because technologists must carry the plates to the readers and wait for them to be electronically processed in much the same way as film cassettes. In response, Fuji has developed two systems with built-in CR plates and readers: an upright chest system called FCR 5501 and a general radiography table called FCR 9502. In these systems, a plate rotates into position for exposure, while another moves into place to be read.

Similarly, Konica Medical offers a phosphor plate system, the Regius, that requires no external plate handling. The upright system, which is dedicated to chest and abdominal imaging, uses an internally mounted phosphor plate over which a CR reader passes, capturing the image and relaying the data for display.

Kodak and Agfa Medical both offer their own families of CR systems, from high-performance products to budget-oriented, compact systems. Lumisys or PhorMax have also developed low-cost CR systems.

Another camp of digital x-ray technology is made up of electronic arrays that immediately transmit data to a network, archive, or workstation for display of the reconstructed image. These signals may be created either directly or indirectly.

Electronic arrays made from amorphous selenium directly generate electrical impulses. Plates made from amorphous silicon register flashes of light that are produced when x-rays strike a thin coating of scintillation material made of cesium iodide. Both selenium- and silicon-based arrays are akin to very large computer chips. Charge-coupled devices, which also record light flashes produced by a scintillator, differ from these arrays in that CCD detectors are composed of many individual chips electronically tied together. Another competing technology, CMOS, is essentially made up of microprocessors that convert light into electrical signals.

At the upcoming RSNA meeting, vendors will almost certainly try to distinguish their products on the basis of their detectors.

The battle over image quality, however, may be incomprehensible to anyone without a background in high-energy physics. Over the last few years, leading vendors, particularly GE and Hologic DRC, have argued over the relative merits of detective quantum efficiency (DQE) and modulation transfer function (MTF) as indicators of how well their detectors capture data. References to spatial frequency, Nyquist frequency, and zero line pairs per millimeter have only served to muddy the waters as these supposedly objective arguments and counterarguments have been twisted to support and contradict the effectiveness of both types of detectors.

"It confuses the customer," said Swissray's Harmon. "The issue should be what gives the best images, what is deliverable, and what works."

WHICH TECHNOLOGY?

The multitude of names, in the context of battling technologies, could make it more difficult for vendors to convince customers that the time for digital x-ray has arrived. A major barrier to its adoption has been uncertainty among prospective buyers about which technology to purchase. GE hopes to re¡solve the problem in a way that will benefit itself and, ironically, its chief rivals, Philips and Siemens, as all three companies have built their radiographic systems around amorphous silicon detectors.

"When you have GE and Philips and Siemens using basically similar technology, you can tell yourself that this technology is here to stay," GE's Maloberti said. "Amorphous silicon technology is what the market is going to choose."

A lot is at stake. GE alone claims to have sunk more than $150 million into the development of its flat-panel technology. The company is continuing to pour money into R&D, focusing on advanced applications, such as dual energy subtraction and tomosynthesis.

"If you don't have the solidity of the company to sustain future development, you won't reap the full benefit of the digital detector technology," Maloberti said. "That's why you will see a concentration of the market on a few players over the next few years."

If he is correct, the debate over the technical merits of amorphous silicon versus selenium, CCD, and other alternative technologies will be moot. Marketing muscle, brought to bear by a confluence of major companies on a single type of technology, will determine the winner, not technical superiority. Whether this happens could be decided in the next 12 months.