In May, the FDA¹ released for public comment a
guidance document intended to ensure that manufacturers’ imaging devices are either suited for pediatric use or labeled with a warning that cautions against use in pediatric populations.
Citing the increased radiosensitivity of children (as compared with that of adults), the greater timeline along which overexposure could manifest itself as cancer, and the potential for children to be exposed to excessive radiation when machines calibrated principally for adults are used, the document would require manufacturers to explicitly incorporate pediatric settings, labeling, displays, and software on all new equipment or label it to caution against pediatric use.
Although everyone takes notice when the FDA issues such guidance, Marilyn J. Goske, MD, who chairs both the Alliance for Radiation Safety in Pediatric Imaging and the pediatric interest group of the ACR® Dose Index Registry, says that the increased focus on pediatric dose mitigation and patient safety is a slow crescendo that began about a decade ago.
Goske, who is also a professor of radiology and pediatrics at Cincinnati Children’s Hospital Medical Center in Ohio, says, “The work that groups like the Society for Pediatric Radiology did helped lay the groundwork to impel discussions about the importance of lowering pediatric imaging dose.”
Although the weeks leading up to the FDA announcement had been filled with releases of high-profile research on the harmful effects of ionizing radiation on children, Goske notes, “I think it’s steady work by many that’s made it seem like it’s come out of nowhere. The recent article² in
Lancet really starting to add to our body of knowledge on medical imaging that’s not being extrapolated from other sources, like the atomic-bomb information.” The things that excite her most are “the collaboration and the communication between critical groups,” Goske says.
An Opportunity to Communicate
Image Gently® sent eight physicians and other medical-imaging professionals to Device Improvements for Pediatric X-ray Imaging (a public workshop held by the FDA on July 16 in Silver Spring, Maryland) to speak specifically with the Medical Imaging & Technology Alliance (MITA), the FDA, and device manufacturers about the particular challenges inherent in trying to image children. “This was our opportunity to communicate with them about what we feel in the trenches,” Goske says.
“We know that 90% of pediatric CT scans are performed in adult-focused practices, not in children’s hospitals,” she adds. “We’re asking the radiologists and radiologic technologists to make sure that they’re doing those 10 CTs a day as safely as possible. This meeting with the FDA and MITA gives us an opportunity to put the spotlight on kids and how to use this equipment and adapt it for use with children.”
Robert A. Uzenoff, executive director, clinical science, FUJIFILM Medical Systems USA, who also attended the workshop, views the event as “a continuation of the collaboration with users and regulators that we’ve had,” he says. “The manufacturers are delighted to have this conversation, but our concern is that some technical factors of the newly required protocols—technical settings such as peak kilovoltage and the use of additional filtration, which focal spot to use, and at what distance to acquire the image—relate to the quality of the exam, and we’re not aware of any professional consensus of what those should be; we’re reluctant to set a standard there.”
To Each His Own
Uzenoff points out that many of those who attended the FDA event in July—MITA and Fujifilm among them—also attended the CR/DR Vendor Summit (sponsored by Image Gently and hosted by the Mallinckrodt Institute of Radiology at Washington University School of Medicine) on February 4, 2010, in St Louis, Missouri.
At that event, manufacturers explained their intention to offer devices with the features identified in the 2008 International Electrotechnical Commission’s standard 62494-1, establishing a standard method of representing exposure index and any deviation from the target index for each exam, Uzenoff says, which benefits pediatric practice, but is not specific to pediatric imaging. Manufacturers were heavily involved in the development of the standard. That summit “certainly validated manufacturers’ decisions to go in that direction,” he says.
“Each manufacturer, on its own timetable, is adopting (or has adopted) it,” he reports. “Fujifilm was one of the first to offer new equipment that complied with that standard, and those features can be added to much of Fujifilm’s legacy equipment with a software update.”
At the July 16 workshop, Uzenoff says, the opportunities and concerns in the area of general-radiography dose reduction were both technical and educational. What equipment users want is some commonality of standards in the area of dose awareness; prior to the existence of the IEC exposure index standard, detector exposure representations have used proprietary measurements, he says. dose estimates have often been linked to proprietary measurements, he says.
Some speakers [medical physicists] at the meeting expressed concern that the proposed device-labeling and testing requirements could have a negative affect on the availability of technology labeled as suitable for pediatric imaging.
“There is concern that some users that manufacturers may find too much burden in the guidance, to allow explicitly labeling devices for pediatric use—so they may be obliged to label them against pediatric use,” Uzenoff reports. Moreover, he says, equipment users do not want to deal with questions from the parents of pediatric patients about whether the devices and protocols with which they had previously been imaging children were safe all along.
Uzenoff says, “The users are saying, ‘Without this guidance, we’re successfully imaging children now, and if you create this standard, what are we going to say to a parent who comes in with questions about previous practices?’” In addition, he says, just as manufacturers are worried about whole-cloth changes in device manufacturing, hospital groups are concerned that pediatric imaging volumes might be insufficient to support buying all-new equipment or paying to upgrade existing equipment.
“Their fear is that there may not be enough demand—that pediatric imaging is maybe 10% of radiology volume,” Uzenoff says. Still (from a manufacturer’s perspective), he left the meeting feeling that a point had been made about the need for professionally developed protocols in general radiography that manufacturers could adapt specifically for their particular detector technologies.
Working Together
Goske says that additional conversations among manufacturers and policymakers are necessary to prioritize, for the vendor community, the order of importance of the pediatric-safety functions of new imaging equipment. “Our medical physicist, Keith Strauss, PhD, gave a very specific, point-by-point response, so that in working together with the manufacturing community, we can recognize the challenges the document creates for the vendor,” she says.
Groups such as Image Gently would look primarily at the impact of radiation-dose reduction in their comments on any standard enacted by the FDA, Goske says. In addition to asking manufacturers to incorporate recommended changes to their devices, she adds, these groups also can help in educating imaging-equipment users in how to optimize and reduce radiation dose.
“They have websites, and they have a lot of materials, but how do you get those materials in the hands of a third-shift person?” Goske asks. Uzenoff agrees: Keeping technologists educated in dose-reduction techniques can be a challenge, particularly on high-turnover shifts. “Providers are interested in new education opportunities so that more technologists can learn and be trained,” Uzenoff says. “That’s part of what Image Gently had been requesting and part of what we see in the guidance, too.”
Matt Skoufalos is a contributing writer for Radinformatics.com.