Fluoroscopy sensor promises increased clinical utility

Varian Medical Systems is betting that its flat-panel fluoroscopy products will spur customers to get off the sidelines and buy into the new era of digital x-ray. Varian strategists believe the company’s flat-panel detectors, based on amorphous silicon technology, will be as widely used in coming years as image intensifiers are today.

The company’s latest product, the PaxScan 4030A, is fueling that optimism. Varian executives describe the first flat-panel detector as large enough and fast enough for clinical applications that require instantaneous imaging of large areas, such as the GI tract.

Its 16-inch field-of-view makes it the largest flat-panel detector capable of fluoroscopy on the market. The 4030A sets a new standard for imaging large anatomical areas, according to Chuck Blouir, marketing manager for Varian’s flat-panel business.

“For most R/F and angio systems sold today, 16-inch image intensifiers are fairly common,” he said. “You need to be able to cover the whole abdomen at once, and that requires at least a 16-inch field-of-view.”

The PaxScan 4030A joins Varian’s other flat-panel products, which include the 2520 and the 4030R. These other products, however, support only radiographic applications.

Hitachi Medical Systems is the first manufacturer to use the new fluoro sensor in a clinical product. Hitachi announced in June its decision to incorporate the 4030A into clinical evaluations of a new gastrointestinal imaging system. Preliminary investigations determined that images obtained using the 4030A produced contrast detail equal to that found in images generated using a conventional image intensifier/charge-coupled device (CCD) camera system. The new study will assess the unit’s performance in a clinical setting.

Clinical tests will be run using a conventional x-ray system modified to accept the 4030A detector. Extensive design changes were not required, Blouir said.

“Hitachi did not design a whole new product from the ground up around the detector,” he said. “Right now Hitachi is trying to prove the clinical efficacy of the flat-panel concept in a GI application before it commits to a whole new product.”

Hitachi chose gastrointestinal imaging as the starting point because of the high volume of GI-related cancers in Japan. But the size of the 4030A, which measures 40 x 30 cm, makes the sensor compatible with other clinical applications as well.

“The panel is a great size and perfect fit for urology systems,” Blouir said. “It is also well suited for angiography.”

Most interventional angio systems today use a 16-inch image intensifier. Unlike bulky image intensifiers and CCD-based systems, the thinner PaxScan 4030A allows OEMs to design a more compact product that is easier to move around or along patients, he said.

“Anywhere that a 16-inch image intensifier is used today we foresee that the 4030A would be a good fit,” he said.

The sensor provides 2.6 line pair per millimeter resolution, slightly better than the only other fluoroscopy-capable panel on the market: the digital sensor built into GE’s dedicated digital cardiac product, Innova 2000, according to Blouir. At 30 frames per second, Varian’s product is competitive with image intensifiers of comparable size.

With frame rates and matrix sizes equivalent to existing conventional systems, the flat-panel detector will be appealing to integrators, Varian executives predict.

“We didn’t want to get into a situation where we had a lot of high-speed custom electronics,” Blouir said. “As a component supplier, we need to create something that can be adapted to a lot of imaging systems. You don’t want to require OEMs to go out and start from scratch designing a new digital imaging process around your product.”

The product’s performance is excellent, Blouir said.

“Because of the rectangular format of the flat panel, which provides more patient coverage than an image intensifier, and improved contrast resolution of the panel compared to an image intensifier, it has the potential to be superior to that technology,” he said.

Hitachi’s decision to integrate the panel into a clinical product is just the first of what Varian hopes will be many such moves, once OEMs and integrators realize the potential that the new product offers.

“It’s not our plan to get into the full-system business and try to compete with GE, Philips, or Siemens,” he said. “We want to make these available to anyone with the ability to complete the system, do the regulatory testing, and get it approved for sale.”

The road from here to there, however, may be a long one, according to Blouir. The lag time between release of a new panel such as the PaxScan 4030A and its adoption and integration by an OEM can be up to two years.

Blouir estimates that there is less than a half-percent penetration today in the radiographic flat-panel market. In the fluoroscopy-capable flat-panel market, only GE has a product.

“(Looking at) the bell curve of a market, we haven’t even started up the front slope yet in terms of fluoroscopy- or angiography-capable products,” he said. “The market for radiographic panels is still three to four years away from becoming high volume. The fluoroscopic market is probably a few years beyond that.”

But component suppliers need to be out on the bleeding edge, according to Blouir.

“It takes time before an OEM can commit R&D dollars to design a product around a component,” he said. “We have to be out in front with the receptor component in order to give the companies something to think about and base their future decisions on.”