Cracking Down: CT Radiation Dose Control

Twitter icon
Facebook icon
LinkedIn icon
e-mail icon
Google icon
 - Dose

Medical imaging procedures offer unprecedented abilities for physicians to detect, diagnose and treat a wide range of diseases and medical problems. An estimated 68 million CT scans, for example, are performed every year in the United States. That’s up from 3 million in 1980. Along with the new capabilities, however, are new concerns about radiation exposure. The issue has come to a head—from education and awareness to updated guidelines and equipment advances.

Radiation dose awareness in imaging studies started a long time before the New England Journal of Medicine (NEJM) published an article last November warning that the overuse of diagnostic CT scans may cause as many as 3 million additional cancers in the United States during the next two to three decades. That’s a risk the radiology community has been well aware of for a long time. But the NEJM article revived the quest to control dose for patients and clinicians. The challenge now is expanding that awareness to the rest of the medical community.

“The traditional approach to diagnostic testing can be characterized as ‘leave no stone unturned’ to achieve the most certain diagnosis possible,” says David A. Schauer, ScD, CHP, executive director of the National Council on Radiation Protection and Measurements. “Under this philosophy, as long as an imaging examination has any chance at all of demonstrating a diagnosis suggested by the clinical clues, then its use is considered reasonable.”

That approach doesn’t take into consideration the impact that any radiation involved in treatment would have on the patient, he points out. “It is clear that breaking this habit and beginning to link selection of patient for imaging examination to likelihood of effect on treatment choice or on patient outcome can help to reduce the economic problems resulting from imaging uses which now adversely affect healthcare costs and to reduce unnecessary radiation exposure of the patient.”

The Alliance for Radiation Safety in Pediatric Imaging launched its new Image Gently campaign in January, with the goal of raising awareness of the opportunities to lower radiation dose when imaging children. At least 600 practices have already signed on and pledge to practice in accordance with the campaign’s recommendation. The medical community has been extremely receptive, says Donald Frush, MD, chair of the American College of Radiology (ACR) Pediatric Imaging Commission.

“This was not taken on as a scare campaign or adversarial campaign,” he says. “It was always based fundamentally on getting information out to practices, organizations and individuals.” Essentially, the campaign is trying to do everything that the NEJM article did not, he says. That includes spreading the word that “CT is really helpful, it saves lives and there are ways to do it appropriately.”

Frush says there has been a growing interest over the past six or seven years to look at radiology’s effects specifically in children and young adults. Some of the cancers that the NEJM article predicted are related to radiation. Since they can take 30 years to develop, excessive exposure to radiation is especially important when imaging children. A two-year-old, for example, has a much higher chance of a 75-year-old of developing one of these cancers. Plus, children are more radiosensitive because their tissues and organs are still dividing and growing. “That kind of tissue has more of a chance of having effects from radiation than tissue simply repairing itself like an adult’s,” he explains. 

Radiologists who specialize in pediatric radiology understand the need to image children differently, says Priscilla F. Butler, MS, senior director, Breast Imaging Accreditation Programs for the ACR, who also was involved in the Image Gently campaign. Most pediatric imaging in the United States, however, is done at community hospitals that probably don’t have a pediatric radiology specialty. “The whole purpose of the initiative was to raise awareness among the radiologists who don’t do as many pediatric patients.”

The campaign has enjoyed “extremely positive feedback,” she says. “Techs feel empowered to bring issues to radiologists. This has been a joint effort among the different players in the radiology department—technologists, radiologists and medical physicists.” Based on the positive response, the ACR is working on an educational campaign for referring physicians and patients and families. “We have to be careful,” she says. “We don’t want to scare people off from having important, life-saving exams. But, we’re dealing with medicine. With everything we do, there is some risk.”

Many opportunities

'Child-size the Dose'  The Image Gently Campaign

Among the new guidelines of the Image Gently campaign launched by the Alliance for Radiation Safety in Pediatric Imaging are:

Significantly reduce, or “child-size,” the amount of radiation used

  • Do not over-scan
  • Scan only when necessary
  • Scan only the indicated region
  • Scan once; multi phase scanning (pre-and post contrast, delayed exams) is rarely helpful

Be a team player

  • Involve medical physicists to monitor pediatric CT techniques
  • Involve technologists to optimize scanning
For more details, visit: ImageGently.org and www.ajronline.org/cgi/content/full/190/2/273. To develop CT protocols for children, visit: www.pedrad.org/associations/5364/files/Protocols.pdf

It’s hard to determine how much effort is enough, Frush says, but “there is a lot of work that can be done on all fronts,” including academia, equipment manufacturers, private practice, physicists and the media. “There are a great many opportunities to get information to people about how to [image] better. Many manufacturers are very sensitive to this issue and want to behave and practice as advocates for patients.”

Frush notes that over the past several years, “there has been a tremendous reception on many [CT system] manufacturers’ part to make both image quality and dose part of their marketing. I applaud them for that.”

Vendors have been working with individual institutions on new software, procedures and equipment design to minimize radiation dose, says Butler. The development in CT has been amazing, she says. “Not all that long ago, there wasn’t a way to automatically vary radiation depending on patient size.” Overall, vendors have been very supportive regarding the control of radiation dose. Efforts such as making dosage information available in their DICOM header have helped to increase physician awareness.

More can be done, however. “I think that there should be automated systems that make sure that the radiation that is delivered is the least that is feasible,” says Daniel Rosenthal, MD, associate radiologist-in-chief at Massachusetts General Hospital. He would like to see all CT scanners be obligated to report radiation doses in a unified, uniform system so doses can be compared. That would be particularly valuable in follow-up situations, for example, where the recent radiation exposure would allow for a second scan of equal quality at a lower dose.

Imaging is a victim of its own success, to some degree. “Imaging has gotten so spectacular, it’s hard for clinicians not to order an imaging study,” says Rosenthal. Redundant and unnecessary exams really need to be controlled, however. “This sort of promiscuous ordering of imaging studies is probably not in patients’ interest.”

Aside from the large CT system vendors working on imaging techniques that reduce radiation exposure while maintaining high image quality, smaller companies also are making inroads on radiation dose control. Rosenthal helped developed RadPort, now distributed by Dictaphone. RadPort helps radiologists determine which exams should be ordered based on a patient’s symptoms. It is based on a set of 1,100 rules that were developed (from the original 200 that the American College of Radiology uses) by Massachusetts General Hospital.

RadPort is helping to reduce the number of inappropriate exams that are ordered, and make sure the right exams are ordered the first time so problems can be diagnosed sooner, treatment can begin sooner and patients aren’t exposed to unnecessary amounts of radiation. In addition, RadPort pre-qualifies exams for insurance coverage, so it helps eliminate problems on the payor end of things as well.

RadPort’s decision support is an effort to increase the appropriateness with which x-ray exams are used, says Rosenthal. A user selects an exam, enters one or more reasons for the exam and then the system feeds back a score to help the user rate the appropriateness of the study and determine whether it is highly indicated. RadPort also offers comparative scores for other, similar exams, some of which do not involve radiation at all.

RadPort takes a very complex calculation and reduces it to a series of rules that will not always be right, Rosenthal admits. “We’ve tried to apply an algorithmic approach, with understanding by users that this is for general case. There will be exceptions.” Once users are accustomed to the system, it results in “very distinct changes in practice initially,” he says. Users first find the system indicating a high rate of use of exams it considers inappropriate. Over time, that usually drops to about 2 percent of all exams.

Another player in this field is RCG HealthCare Consulting, which offers RadOPS-CT, a service that helps practices reduce radiation dosage for patients undergoing CT exams. The service assesses current CT exam practices and protocols, develops a radiation exposure profile, delivers new, optimized CT protocols proven to markedly reduce patient dose, provides training and support for technologists and radiologists, and monitors periodic dosage results to identify further opportunities for refining the overall process.

On average, the radiation exposure service reduces exposure by up to 60 percent, according to Dushyant Suhani, MD, director of CT radiology at Massachusetts General Hospital, where the technology was developed. By reviewing protocols that can reduce exposure without sacrificing quality, facilities can focus on improving quality and increasing patient safety. “It’s valuable to measure radiation exposure and it’s good operations to measure exposure,” David Charpie, RCG executive director.

Although the issue is quite complex, the confluence of technology, protocol, workflow and other strategies plays a significant role in reducing unnecessary radiation exposure.

The service lets RCG help practices that don’t have the same resources. “We see this as a journey, not a product we drop on them.” That includes creating and setting up protocols for most clinical indications so that technologists don’t have to do a lot of technical changes in parameters for each patient.

On the horizon

Controlling radiation dose is “very vexing,” says Rosenthal. Beyond patient safety, there are financial considerations. Studies have shown, he says, that up to 30 percent of imaging studies are unnecessary. Healthcare expenditures are steadily creeping up to almost 20 percent of the U.S. gross national product, and imaging has been growing in double-digit numbers for several years. “It’s unrealistic, however, to think that imaging will become flat or reverse because imaging is growing more powerful and useful in medicine. It has to be brought down from a raging bonfire to a little flame.”

The focus on controlling radiation dose probably will face “consistent and growing interest,” says Charpie. “I think there’s going to be a continuing pace to it.” That pace is dependent on the time and resources organizations can put against the problem, he says.

Beyond the organizational level, physician organizations, physicists, equipment manufacturers, professional groups and even the federal government will play a role, says Suhani. He likens the situation to that of global warming. “There is no single strategy that is going to work and they will happen at multiple levels.” In the next few years, he “envisions that each and every site in the world will have a better approach.