Pediatric Radiologists Thrust Radiation Safety into Spotlight

Donald P. Frush, M.D. Duke University Medical Center

Robert K. Zeman, M.D. George Washington University Medical Center

While radiologists have long been vigilant about radiation dose, recent outreach by the pediatric radiology subspecialty has inspired the strongest directives yet for professional organizations and industry.

Adult patients generally trust that the benefits of CT scanning outweigh the risks of their own radiation exposure, but parents tend to ask more questions about the increased risk to their children, said Robert K. Zeman, M.D., professor and chair of radiology and radiation oncology at George Washington University Medical Center in Washington.

"Many of us who practice adult radiology had concerns about dose," Dr. Zeman said. "But it is our pediatric radiology colleagues that have really mobilized industry and our professional organizations to take action."

Pediatrics Well Positioned as Leader

Pediatric radiologists have naturally emerged as some of the key figures in radiation dose management, as many are old hands at techniques to reduce their young patients' exposure. Donald P. Frush, M.D., and his colleagues at Duke University Medical Center now use scanners that incorporate the Broselow-Luten pediatric color-coded system, which assigns one of nine dosage zones based on the height and weight of the child.

"They're the same zones used for medications, fluids and equipment like endotracheal tubes," said Dr. Frush, chief of the division of pediatric radiology. GE Healthcare liked the idea, he said, and obtained permission from Broselow-Luten to use the same color zones in their CT scanners.

"The technologists really like the built-in protocols," said Dr. Frush. "There's no magic here, really—just a way to build protocols directly into the scanners so the appropriate amount of radiation is given to kids of varying sizes."

The idea that CT is a wonderful modality for specific problems—and if the exam is necessary, do it with the lowest radiation dose possible—is on the mind of all radiologists, said Marilyn Goske, M.D., Silverman Chair for Radiology Education at Cincinnati Children's Hospital Medical Center and past chair of the board of trustees for the Society for Pediatric Radiology (SPR). As SPR past-president, Dr. Goske helped establish Image Gently, along with Dr. Frush and a steering committee from the American Society of Radiologic Technologists, American Association of Physicists in Medicine and American College of Radiology. The pediatrics-focused campaign is gaining attention with a simple message, said Dr. Goske: "When CT is the right thing to do, child size the kVP and mA. One scan (single phase) is often enough, and scan only the indicated area."

Manufacturers Follow Suit

Manufacturers are becoming acutely mindful of radiologists' demand for conscientious imaging, said Drs. Goske and Frush. "All the major vendors now include radiation dose safety issues in their marketing platforms," said Dr. Frush. "Focus is turning to creating more efficient detector technology to increase image quality."

Added Dr. Goske, "Radiation dose has caught the attention of manufacturers not only because it's the right thing to do, but also because it sets them apart from their competitors."

In addition to manufacturers, Dr. Frush said that in recent years he has been pleased to see colleagues taking an active interest in dose reduction. "I see that when we get studies from other institutions now, they're tending to use much lower doses than they did seven or eight years ago," he said. "Before that, kids were scanned at the same settings as adults."

Since launching the Image Gently campaign, the Alliance for Radiation Safety in Pediatric Imaging has assembled 23 member organizations and more than 1,300 individuals have taken the Image Gently Pledge. "The organizations represent about half a million radiology professionals," Dr. Goske said. "We have now gone international, with member organizations not only in the U.S. but beyond our borders."

ACR facility accreditation and other similar programs provide an incentive for dose reduction, and industry and regulatory agencies are also taking note, said Dr. Frush. He added that the U.S. Food and Drug Administration (FDA) and the National Imagery and Mapping Agency (NIMA) are calling for more consistent dose estimates, recording and archiving estimates. "The Alliance's Vendor Summit will try to come to terms with how to do this," he said.

Vendor Summit Seen as Pivotal

Supporters of the pediatrics-focused Image Gently campaign are promoting a simple message: When CT is the right thing to do, child size the peak kilovoltage (kVP) and milliamperes (mA). Remember that one scan (single phase) is often enough and scan only the indicated area. More information about Image Gently is available at www.imagegently.org.

The Image Gently Vendor Summit, scheduled for Aug. 20 at Cincinnati Children's Hospital, will include representatives of major CT manufacturers, Image Gently organizations, the FDA and the Medical Imaging and Technology Alliance, a division of the National Electrical Manufacturers Association. The goal of the summit is to encourage manufacturers to develop products with radiation dose in mind and also incorporate the campaign's message into their training programs and installation procedures.

Radiologists warn, however, against expecting uniform standards for all dosage protocols—neither the equipment nor the operating guidelines will give radiologists a magic number. "There's not going to be a single way that all the scanners work—it's just not the nature of entrepreneurship," said Dr. Frush. "And there's no single dose in any examination that's going to be appropriate for all individuals. The best we can do is establish maximum and minimum dose."

Added James H. Thrall, M.D., radiologist-in-chief at Massachusetts General Hospital and chair of the American College of Radiology (ACR) board of trustees, "How low one can go is partly up to the person who must interpret the images. We will not have uniform agreement."

Individuals Must Seize Dose Reduction Opportunities

Ultimately the radiologist must decide in his or her own practice what constitutes a diagnostic quality exam, said Dr. Zeman. "There is, however, considerable 'low hanging fruit,' in terms of opportunities to reduce dose," he said. "Those opportunities do not revolve solely around reducing mAs.

"Radiology practices should closely look at their CT protocols and consider using automatic dose reduction on all exams, more aggressively on exams that are unlikely to harbor subtle low contrast lesions," Dr. Zeman continued. "A weight-based patient dose nomogram is another effective tool for limiting dose. Practices should not automatically use the thinnest sections allowed on a particular scanner, but rather use slightly thicker sections which will decrease image noise and allow for lower doses. Using pitches of greater than one is a great way to reduce dose while reducing scan times."

One of the simplest ways to cut dose, Drs. Zeman and Goske point out, remains the same—scanning only the necessary area. "For example, if you have a child who has chronic hip dislocation, has had surgery to reduce the hip and is in a cast, the only way to look through the cast to see the hip is with a CT scan," said Dr. Goske. "However, we only need to see gross anatomy, so we can bring the dose way down and do a very short spiral, maybe 3 centimeters. The referring doctor may order a scan of the pelvis, but we don't need the whole pelvis. We just need a couple of centimeters through the hip joint.

"The third phase of the Image Gently will be reaching out to parents," Dr. Goske continued. "But we must first remind radiologists, radiology technologists and physicists, and then referring physicians."

Added Dr. Zeman, "We are not currently positioned to be the gatekeepers of the entire referral process, but we can be the gatekeepers of patient dose."