Vendors debut new technologiesin quest to digitize x-ray exams

Did Du Pont divestiture affect timing of DR introduction?

A battle royal is looming among medical imaging companies overmethods to digitize conventional x-ray exams. At last month'sRadiological Society of North America meeting, new technologiesfrom Du Pont, Swissray and other firms offered hope that analogx-ray can be easily integrated into the filmless-hospital networksthat are radiology's future.

The stakes involved are huge: Du Pont estimates that thereis an installed base of some 200,000 traditional x-ray units inthe developed world. Those units must be converted to digital,at least for facilities that want to take advantage of the efficienciesbrought by digital image management networks.

Computed radiography or x-ray film scanners have long beenthe only solutions for digitizing conventional x-rays, but eachhas disadvantages that have prompted companies to look for othermethods.

Du Pont's debut of direct radiography (DR) at the RSNA conferencerepresents the culmination of the vendor's quest to improve onCR, according Deborah DuBois, new business manager for Wilmington,DE-based Du Pont.

DR consists of a detector based on an amorphous selenium thin-filmtransistor panel that converts x-ray photons into analog voltage,which is then converted into digital signals by analog-to-digitalconverters. The detector is self-scanning, allowing digital x-rayimages to be produced without the need for a dedicated readerof the type used in CR. Images are sent directly from the detectorto a DICOM-compatible workstation, where they can be routed withinan image management network. Du Pont showed panels on the technologyat last year's RSNA meeting (SCAN 2/15/95).

To demonstrate DR, Du Pont set up a video microwave link betweenits RSNA booth and Loyola University Medical Center's Foster G.McGraw Hospital 11 miles away. A DR prototype scanned a phantomand sent the images to Du Pont's booth seconds later as standing-room-onlycrowds looked on.

Du Pont believes its technology offers advantages over CR,both in ease of use and in image quality. Because DR does notrequire a dedicated reader, it should be less expensive and easierto use than CR. Resolution is 3.6 line pairs/ mm. That may notseem high, but image quality is improved due to the system's 80%modulation transfer function (MTF), which is a method of measuringhow well an x-ray receptor responds to an input signal. High-resolutionx-ray film has an MTF of 60% while CR is below 40%, accordingto DuBois.

DR produces 14-bit images, compared to 10-bit Fuji CR and 12-bitKodak and Agfa CR. Du Pont also believes that using photoconductorsto convert x-rays to electrical signals avoids light scatter createdwhen CR phosphor plates convert x-rays into light and then lightinto electrical signals.

Du Pont plans to market DR as a 14 x 17 cassette-style buckythat will retrofit to x-ray devices in the field, according toDuBois. The company plans to have a product on the market by early1998.

That's a long way off, and some industry observers speculatedthat Du Pont timed its DR announcement in an effort to enhancethe value of the Medical Products group, which was put up forsale earlier this year (SCAN 6/7/95). Du Pont said it hopes toannounce a buyer for the business four to six weeks after theRSNA meeting.

While DR unquestionably makes Du Pont a more attractive acquisition,the company's motives may have been more competitive in nature:to short-circuit purchasing of other technologies until its productis on the market.

"One of the main reasons (for the announcement) was toallow people to begin their planning," DuBois said. "We'vehad some people talk about delaying sales of computed radiographyand waiting, maybe leasing computed radiography, maybe stickingwith film and a digitizer."

Swissray's AddOn-Bucky. Taking a slightly different means toa similar end is x-ray manufacturer Swissray. The company madeits RSNA debut with AddOn-Bucky, a cassette-style digital detectorthat uses a scintillating screen to convert x-ray photons intolight, which is converted into digital information by four charge-coupleddevice (CCD) arrays.

The detector has a resolution of 5.6 lines/mm, comparable to400-speed screen-film systems. Images acquired with AddOn-Buckywill be sent to a workstation called SwissVision, which supportsthe DICOM standard and will display images in a 1750 x 2150 matrix.

Like Du Pont, Swissray plans to market AddOn-Bucky as a retrofitto conventional x-ray tube stands, tabletops and wall-mountedunits. Swissray lacks Du Pont's sales and marketing power, butit does have one major advantage: time. The company has appliedfor Food and Drug Administration marketing clearance for AddOn-Buckyand plans to begin selling the detector early next year.

Swissray has not yet decided how it will market the device.It will build up its own network of distributorships, but is alsointerested in OEM alliances, according to Ueli Laupper, managingdirector of the Hitzkirch, Switzerland firm.

Du Pont and Swissray are not the only firms developing directdigital detectors, however. One firm, ThermoTrex Medical, believesits digital detector technology can be adapted from full-viewdigital mammography applications to conventional x-ray.

ThermoTrex Medical was formed following the acquisition ofBennett X-Ray this year by ThermoTrex Corp., which also owns Lorad(SCAN 9/27/95). The company has been integrating the full-viewdigital mammography programs of Lorad and Bennett, which had beenworking on the technology independently before the acquisition.

Because mammography's image quality requirements are so rigorous,any digital detector suited for full-view digital mammographywould be more than adequate for conventional x-ray applications,according to Hal Kirshner, president and CEO of ThermoTrex Medical.The company is developing a second-generation full-view digitaldetector using a flat-panel detector that could retrofit to conventionalradiography systems, Kirshner said.

"We're currently working on a first-generation full-breastdigital system that will lead to a second-generation flat-paneldetector that we feel has a broad application across R/F and generalx-ray," Kirshner said. "If you can detect a tumor usingdigital in the breast that you can't see in film, you've achieveda level of detection that will be superior to any other devicewhen you cross over to general x-ray."

CR advancements. Where does all this leave computed radiography?By all indications, the technology is beginning a major growthcurve, spurred by the trend toward digital image management. Inaddition, nagging doubts about CR's spatial resolution have beenresolved by technological advancements.

Kodak has experienced success in the modality since bringingout Model 400, its new CR reader, in June. The Rochester, NY,company has shipped 50 Model 400 readers worldwide to date, accordingto Michael Moehring, manager of worldwide marketing for computedradiography. Kodak announced an OEM agreement with Siemens atthe RSNA meeting, and the relationship should increase sales by20% to 30%, Moehring said. The firms will integrate Model 400into Siemens' Sienet PACS line.

Agfa is also making a big CR push. The company's ADC 70 readerwas prominently featured in its RSNA booth. Agfa, of RidgefieldPark, NJ, had been prevented from marketing ADC 70 in the U.S.due to patent infringement claims from Fuji, but those issueswere resolved with a licensing deal between the companies in July(SCAN 7/19/95).

Market leader Fuji has seen its CR sales double in 1995 overlast year, according to John Strauss, national marketing managerfor CR at Stamford, CT-based Fuji. That growth rate should increasenext year due to recent alliances the company has signed withGE, Picker and Siemens. It has also signed on PACS vendor Loralas an OEM, Strauss said.

Fuji released three new CR readers at the RSNA meeting thatexpand its fifth-generation CR technology to new applications,such as tabletop x-ray and energy subtraction (SCAN 11/22/95).Fuji believes that direct radiography is intriguing, but doesnot pose a serious threat to CR.

"It is interesting technology," Strauss said. "Doesit mean it's near commercial availability? No. (A 1998 introduction)is a very aggressive development schedule."

Even when DR and other technologies are on the market, Strausssees a complementary role between them and CR. In any event, userswho postpone CR purchases until direct radiography or some othertechnology is available will be missing the productivity advantagesCR confers, he said.

"It's like the computer industry. You could hold off twoor three years and buy one that's more powerful, but what haveyou lost between now and then in productivity?" Strauss said."CR is a proven technology. We feel that it is the only viableclinical tool for the foreseeable future."