CMOS technology for digital x-ray edges closer to commercialization

Cares Built’s Clarity 7000 under review at FDA

A technology used for military and space applications may be the next trend in digital x-ray, if a few imaging vendors have their way. Although the majority of manufacturers have chosen to work with computed radiography, charge-coupled devices (CCDs), or amorphous silicon- or amorphous selenium-based flat-panel detectors, a handful of firms, including Cares Built of Keyport, NJ, are developing systems that use complementary metal-oxide semiconductor (CMOS) chips.

CMOS technology is the same as that used for modern microprocessors, memory chips, and integrated circuits, according to Photobit of Pasadena, CA, a spinoff of the National Aeronautics and Space Administration’s Jet Propulsion Laboratory and one of the companies that produces the CMOS chips and sells them to OEMs. Each CMOS chip carries an array of cells, or pixels, that receive light and convert it to an electric charge. Each pixel contains not only the sensor element but also active transistor circuitry for reading the pixel signal.

The chips have been used in military and space applications for more than two decades, particularly by NASA. But companies like Cares Built and Rogan Medical Systems, based in Pewaukee, WI, as well as Amherst, NY-based Sensor Plus, believe that CMOS could offer key advantages in the digital x-ray market compared with other techniques, including lower costs, higher image quality, and decreased power requirements.

Since CMOS chips are made like other integrated circuits, they can be manufactured at lower cost than CCDs, which require a different manufacturing process. CMOS chips also require less power than CCD devices do, according to Scott Smith, research engineer for x-ray imaging hardware and systems at Sensor Plus, which is developing a digital mammography device that incorporates both CCD and CMOS sensors. (SCAN 10/28/98)

“CMOS technology is really taking off right now,” Smith said. “(The chips) are very low power while CCD devices require a complex electronic setup with multiple voltages. So they’re low power, they’re low cost, and they’re simple to make.”

Private digital x-ray developer Cares Built debuted its Clarity 7000 digital x-ray detector at the 1997 RSNA show as a work-in-progress (SCAN Special Report 12/97). Last month, the company reintroduced Clarity, proclaiming it a viable digital replacement for x-ray film and emphasizing its CMOS technology. Clarity is a 17 x 17-inch detector with a 7K x 7K matrix and resolution of 7 line pairs/mm, more than twice that of other detectors on the market, according to Marc Regan, vice president of sales and marketing.

“We’ve been trying to create an extremely high quality image, and have been able to do that with CMOS technology,” Regan said. “We looked at existing buckies and asked ourselves how we could get a receptor that wouldn’t compromise on resolution. To our knowledge, our technology has five times more spatial resolution than (a CCD- or amorphous silicon flat-panel) system.”

Although the detector has not yet been cleared by the Food and Drug Administration, Cares Built expects to receive approval by the end of the year, according to company executives, and will offer Clarity 7000 as a drop-in retrofit for general radiography systems. The firm will also offer Clarity 7000 as part of its Flex-Ray line of complete digital x-ray systems, including AllRad for high-end radiography; GenRad for general radiography; AllRad T and GenRad T, fulcrumless tomography versions of the two systems; and VertiRad and VertiRad T, wall bucky units.

In August, Cares Built initiated its first private placement with Network One Financial of Redbank, NJ, for $2 million of preferred convertible shares at $2.50 per share. Network One has so far sold $625,000 worth of shares. Cares Built expects to go public in the next 18 to 24 months, and plans to use the funds raised by the offering to promote Clarity before the upcoming RSNA show, as well as to gear up for high-volume production, according to Tim Telymonde, president of Cares Built.

“We’re backed up so far with orders and requests for information (about Clarity) that a lot of the private placement will go to hiring staff to handle the interest,” Telymonde said.

Cares Built has begun forging alliances with other firms. The company already has a relationship with Rogan, which displayed a Clarity 7000 unit at last year’s RSNA show (SCAN Special Report, 1/99). In March, Cares Built signed an OEM agreement with Siemens AG of Erlangen, Germany, under which Siemens provides Cares Built with conventional radiographic equipment to sell under its own label in the U.S.

Cares Built and Siemens are also in negotiations for another agreement in which Siemens would use Clarity 7000 for its general radiographic products, subject to Clarity’s FDA clearance and Siemens’ corporate approval, according to Cares Built.

A deal with Cares Built for its digital detector would seem to affect Siemens’ relationship with Trixell, the French digital detector joint venture company formed by Siemens, Philips, and Thomson Tubes Electroniques; Trixell supplies Siemens with flat-panel, amorphous silicon detectors used in its FDA-cleared Multix FD and Thorax FD digital units (SCAN 5/12/99).