Cincinnati meeting starts long road to harmonizing CT dose displays

Advocates for reducing pediatric CT radiation dose agree that a recent meeting at Cincinnati Children's Hospital was a productive first step toward harmonizing the way CT scanners display radiation dose. But participants at the conference also concur that it could take years for the changes that were discussed to be implemented.

In an August 20 meeting organized by the Alliance for Radiation Safety in Pediatric Imaging, representatives from academia, government, and industry joined to discuss ways that vendors can help reduce CT dose. Participants included academic societies that are members of the alliance, as well as members of the U.S. Food and Drug Administration (FDA), the Medical Imaging and Technology Alliance (MITA), and representatives from the four major CT vendors: GE Healthcare, Philips Healthcare, Siemens Healthcare, and Toshiba America Medical Systems.

Currently, dose indices provided by imaging manufacturers are based upon standard phantoms that are models of adult bodies. If not properly corrected, these can lead to large errors in dose for the smallest patients. Children are more sensitive to radiation, and cumulative radiation exposure from CT scans over the years can cause adverse effects, such as cancer.

CT scanners also vary from manufacturer to manufacturer in their techniques to minimize radiation dose, and dose displays are not only deficient for pediatrics, they are inconsistently displayed from scanner to scanner. Different terms are used, or a phrase that means one thing for one manufacturer may mean something else entirely for another.

"We'd like to have the manufacturers change the dose indices that they display so that they are a more reasonable index of the radiation energy that's being delivered to the patient as a function of their body size," said Keith Strauss of the American Association of Physicists in Medicine (AAPM). "Basically, we need to improve on the information that's already displayed."

Participants at the summit spent the first half of the day discussing the potential of developing a dose metric modeled after a pediatric patient that is consistent across all vendor and machine standards. There were suggestions for better dose estimations on scanners, as well as talks on standardizing nomenclatures, displays, and archiving.

"We agreed to use a representative pediatric phantom to measure our dose and to use the same metrics of measurement across each of the vendors so that you can compare them," said David Dobson of GE. Some steps toward this goal include improving the software and hardware characteristics to produce better images with lower doses.

The second half of the day was focused on ways of further educating and continuing awareness of dose issues among clinicians. Greg Morrison, executive vice president and chief knowledge officer of the American Society of Radiologic Technologists (ASRT), said there was a consensus among meeting participants that more needs to be done to spread awareness.

"There is general support that something additional should be done in order to continue the forward movement of this campaign and help people be aware that the issue of pediatric dose reduction in CT is an important one," Morrison said.

CT procedure volumes have been rising in recent years, and with this growth is increased awareness of radiation dose, according to Christianne Leidecker, Ph.D., manager of scientific collaborations at Siemens.

"The more patients you have, the more you need to be careful to use appropriate imaging parameters in each and every case," Leidecker said. "The increasing awareness goes hand in hand with the increasing number of CT scans and number of patients imaged."

Vendors agreed to make their educational staff more aware of the alliance's Image Gently campaign and to add it to their educational programs, and the alliance said it would work with the four major CT vendors to create more educational material.

The purpose of this summit, however, was not so much to make immediate, overnight changes, as much as to bring together the different communities involved in pediatric CT -- radiologists, physicists, and regulatory agencies -- and to open doors to move toward improvements. The alliance is planning to meet again on December 1 to further discuss its progress.

Dr. Donald Frush, chair of the alliance's commission on pediatric imaging, said that it could take years to achieve the level of standardization that the meeting participants agreed is necessary.

"I don't know exactly how long that's going to take to do, but there needs to be a great deal of discussion from a variety of communities ... to make sure what is done meets the needs of all of those groups," Frush said.

"I think the first step has been taken -- we had this meeting and we all agreed there's an issue that we can address," said Rich Mather, Ph.D., Toshiba's senior manager of clinical sciences in the company's CT business unit. "The next step is for the communities to work together to define those steps."

"This was an extremely successful meeting," continued Frush. "It was historical, because all of the major vendors, the technical expertise, physicists, and engineers were all there in one room to address an issue related to pediatric radiology ... To get them together ... to discuss their equipment and ... to do it for the good of children was extraordinary."

By Caitanya Min contributing writer
September 17, 2008

Related Reading

Study: Radiologists dial back on pediatric CT settings, September 4, 2008

Meeting to examine pediatric CT dose, August 18, 2008

FDA posts pediatric imaging advisory, June 25, 2008

House resolution advocates lower pediatric x-ray dose, May 27, 2008

CT experts grapple with rising concerns about radiation dose, May 14, 2008

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