FDA releases rules on regulation of solid-state digital x-ray devices

July 9, 1997

Next-generation devices to go through 510(k) processThe next generation of x-ray digitization systems will be reviewed using the 510(k) process at the Food and Drug Administration, not the more rigorous premarket approval (PMA) process. And

Next-generation devices to go through 510(k) process

The next generation of x-ray digitization systems will be reviewed using the 510(k) process at the Food and Drug Administration, not the more rigorous premarket approval (PMA) process. And although clinical data will be required to support submissions, extensive studies will probably not be required.

Details about the kinds of information that the FDA will require from manufacturers and how those data might be presented are contained in a new publication called "Guidance for the Submission of 510(k)s for Solid State X-ray Imaging Devices," which the FDA made available last month. The guide is only a first draft, so the language will likely change before a final version is completed by the end of 1997 or early next year. The document is now open for public comment.

Despite the potential for revision, the broad boundaries mapped out by the agency in the guidelines are likely to remain the same. Therefore, the guidelines provide at least a general indication of what the FDA will require from manufacturers seeking clearance to market digital x-ray equipment in the U.S., according to Robert Doyle, author of the guidance.

"With nothing else in place, people can use this draft and proceed with product development with at least a good idea of what information we're looking for in a submission," said Doyle, a scientific reviewer in the Computed Imaging Devices Branch of the FDA's Center for Devices and Radiological Health.

The industry had been expecting the FDA to require a more extensive review process than is required of conventional x-ray equipment, particularly in light of the agency's decision to require clinical data to support the substantial equivalence of digital mammography systems to their film-based counterparts (SCAN 10/11/95). There was, however, no certainty that this model would be extended to other types of digital x-ray equipment, such as digital radiographic and fluoroscopic equipment. The draft guidance lays those concerns to rest.

A clinical protocol has been incorporated into the guidance addressing digital radiographic and fluoroscopic systems other than those used to generate mammograms. For these products, developers must conduct and report the results of a study of 30 or more clinical image pairs that show the device to be diagnostically equivalent to conventional systems already on the market.

One of the first of this new generation of products will come from Sterling Diagnostic Imaging, which is developing its Direct Radiography x-ray digitization system. Executives at the Greenville, SC, company decline to provide details on the status of its submission regarding the product, saying only that DR is on track for commercialization in 1998. It is known, however, that clinical studies are under way at Thomas Jefferson University Hospital in Philadelphia, as well as the Cleveland Clinic.

At least 50 patient chest and abdomen studies using a 14 x 17 detector array have been conducted at Thomas Jefferson, and the images compared with conventional film studies by a panel of three expert radiologists, according to the company. The Thomas Jefferson researchers presented findings from their work at last month's International Congress of Computer Assisted Radiology (CAR) in Berlin. Sterling will most likely use the study to support its DR submission to the FDA.

Such clinical studies, while necessary for at least the near future, may not always be required by the FDA. In describing the rationale for the guidelines published last month, Doyle explained that the agency wants to be sure that digital technologies are diagnostically equivalent to conventional ones before allowing them on the market.

"We expect that after the first half dozen or so submissions of digital devices, and after (healthcare providers) get a chance to start using them, we can make these early submissions into predicates for the digital systems that follow," Doyle said. "If they use the same technology, then we will no longer need the clinical studies."