Like One Hundred X-Rays? Exposure Involved With CT Scans

Like One Hundred X-Rays? Exposure Involved With CT...

Like One Hundred X-Rays? Exposure Involved With CT Scans

Matthew Robb

A child falls from a playground swing. A teenage girl complains of acute abdominal pain. A pregnant woman takes a nasty spill while getting out of her sports utility vehicle.

According to the National Center for Health Statistics, these and countless other scenarios prompted 110.2 million emergency department (ED) visits nationwide in 2002, resulting in an estimated 65 million CT scans—a roughly 700% increase over the past decade.

Hailed for its diagnostic powers, CT imaging is also stirring some concern over radiation exposure and widespread use. A growing body of evidence published in peer-reviewed journals finds this scanning technology—still described by some radiologic professionals as essentially benign—exposes patients to often much higher radiation doses than commonly believed. Public health officials worry that these critical new findings are not making their way to consumers, and a new study corroborates this. Actual awareness levels—even among hospital medical professionals—are surprisingly low.

Education Shortfall

In the May issue of Radiology, Howard P. Forman, MD, associate professor of diagnostic radiology and management at Yale University, revealed the results of a survey involving Yale-New Haven Hospital patients, ED physicians, and radiologists. Researchers looked at awareness of radiation dose levels and risks and benefits. The results were not encouraging. Had Forman passed around a basic pop quiz rather than a survey tool, many ED physicians and radiologists at this prestigious hospital would have failed. Says Forman, “We found a lack of education at every level of the ED chain of communication.”

Noting the prevailing view that one abdominal CT scan has an estimated radiation equivalence of 100 to 250 chest x-rays, Forman’s team found that only 22% of surveyed ED physicians, 13% of radiologists, and zero patients could identify this equivalence dosage within an acceptable range. In fact, 92% of patients, 51% of ED physicians, and—most surprising—61% of radiologists incorrectly believed a single CT radiation dose is equivalent to no more than 10 chest x-rays, thus underestimating the exposure by 90% to 96%. To complete the picture, while almost one-half of surveyed radiologists believed a single CT scan increased lifetime cancer risk, just 9% of ED physicians and 3% of patients believed similarly.

Sifting through the data, Forman found that Yale ED doctors simply weren’t communicating. Fewer than 7% of patients reported that their ED physicians—those actually ordering the scans—discussed radiation issues with them. But reflecting on the study’s surprising findings, Forman thinks poor communication is a secondary issue. “Before patients can receive information about radiation risks,” he notes, “they need informed caregivers, but if ED physicians and radiologic physicians aren’t informed, then there’s really no hope that the patient is going to be.” The implication is clear: When patients are given bad or incomplete information—or none at all—they are apt to make ill-informed decisions. Forman notes that such decision making is especially critical when children are involved, as CT exposure is cumulative. Echoing the consensus view, researchers in the 2001 American Journal of Roentgenology concluded that childhood exposure “will result in significantly increased lifetime radiation risk over adult CT.”

Forman says the Yale study poses serious questions to the radiology community on matters of professional duty, medical consent, outreach, and appropriateness of CT scanning as a frontline diagnostic tool. He and other researchers and policy experts say things must change, that patients should not be exposed to cancer risks without proper education and notification of alternative modalities.

In short, they say the research speaks loud and clear. The problem is that few seem to be listening.

New Technologies, New Issues

Acknowledging that the CT scan has become the gold standard of diagnostic imaging, Yale-New Haven Hospital physician assistant Andrew Meiman says his own ED experience falls in line with Forman’s findings. “There’s a lot of inadequate information and misinformation out there,” Meiman says. “My impression is that patients are not being told about the risks and that providers may not know or offer this information.”

Part of the problem, Meiman says, is the explosion of medical knowledge that finds generalists struggling to keep abreast. “It’s difficult to be up to speed when you are dealing with new and changing technologies, different machines at different facilities, and the understanding that various body parts should be scanned with varying radiation levels.” Pausing, he adds, “It’s difficult, but it’s not impossible.”

Forman agrees. “Perhaps 25 to 30 years ago,” he says, “the full armamentarium of radiology involved relatively little radiation. Few patients had more than one CT scan in a lifetime and high-radiation studies were rare. Today, by contrast, CT scans have become the first test for a whole host of conditions. It’s not unusual for patients to have 10 to 20 CT scans in one to two years, which I think any informed professional would say is within the cancer-causing range.”

Some observers argue that ED and referring physicians cannot always find time for patient education, an argument Forman rejects. “Physicians don’t much relish the time required to explain side effects of new drugs,” he says, “but they do what is expected of them. When you’re dealing with radiologic imaging procedures, the expectation should be at least that high.” He notes that while older equipment may be sources of higher radiation exposure, Yale and other flagship institutions do the kind of advanced imaging that often entails significant radiation exposure. “When we have a trauma patient come into Yale,” he says, “they’re likely to get CT exams of their entire body. Rural providers may not be able to provide this full gamut of imaging. They may rely more on clinical skills that, by the way, might not necessarily be in the patient’s best interest.”

He continues: “I don’t want to overstate the amount of unnecessary imaging I think exists, and I do see the enormous benefits of this technology. Ultimately, I think there are clear cases where they are obviously needed and some that we might question, but most are in a gray zone and, in there, we are not going to be able to dissuade their usage.”

Can You Hear Me Now?

Drawing on more than 20 years of experience as a radiologic technologist, Anne Edwards, RT(R)(CT), offers her perspective. “We understand now that CT radiation exposure is higher than was originally documented back in the 1980s,” she notes. “When I started doing CT back in 1983, I would tell patients, ‘We’ll do a quick CT scan. Don’t worry, it’s not that much radiation.’ Well, we now know that, yes, it’s actually one of the higher radiologic studies there is.”

Edwards, supervisor of imaging services at St. Luke’s Hospital in Cedar Rapids, Iowa, says that if awareness of these risks has filtered down, it has filtered slowly and unevenly. “I think some of the newer technologists—those coming out of school—know the risks, but if you don’t read the literature and don’t get appropriate continuing education, you aren’t going to keep pace. Some of the older technologists in the field don’t understand that some of the new scanners allow for adjusting radiation limits for pediatric and other patients.”

Part of the difficulty, she says, is countering the whole-body scan craze that has recently swept the nation. When the cash-flush worried well walk into clinics demanding an “Oprah body scan,” it’s hard to say no. “She certainly sensationalized it,” Edwards says, “which means imaging centers across the nation were inundated with calls. The marketing of these services really creates the perception that it’s all very harmless.”

Notably, regulators at the FDA have voiced concern about “unregulated boutique clinics where patients pay … to get CT scans not for diagnosis, but for regular health screening.” The FDA notes that it has no power to control the use of scanning machines inside medical offices.

The issue of whole-body scanning aside, Edward notes that a “let’s do a quick CT” mentality still pervades the medical profession—a testament to the technology’s awesome power but also indicative of sometimes reflexive decision making.

Learning and Teaching

Outlining his prescription for change, Forman says, “It’s essential that we empower patients to ask questions and to better prepare physicians—referring and providing—to answer their questions.”

Meiman agrees. “I think better information needs to be made available to providers in their training and in their daily work so they have better information about the risks,” he says. “We need to focus on developing better education programs in continuing education and in the initial schools: medical, physician assistant, nursing, and radiologic technology.”

Forman suggests that radiology service providers prominently note on patient reports exact radiation exposures. “I think we would see an enormous change in behavior,” he says, “if physicians were actually able to look at a patient’s report that says, ‘This study was normal and, by the way, this study was the equivalent of 100 x-rays.’” It would then be the medical profession’s responsibility to make sure the patient understands the attendant risks.

Looking at the macro level, Forman says radiologic technologists thus find themselves stuck in the middle. Informed consumers arrive at imaging centers feeling whipsawed by conflicting information—CT scans are good, CT scans are bad—which instead of allaying concern can actually stir confusion, uncertainty, and possibly resistance to needed studies. “Technologists are as much caregivers as anybody in this equation,” he says, “so they should feel empowered to answer questions about radiation exposure and to reassure patients, in an elective setting, to talk to their physician if they have any concerns about getting the study.”

Edwards notes the precarious tightrope technologists must negotiate as middlemen between presumably uninformed physicians and apprehensive patients. “Technologists can’t dictate what a physician orders,” she says, “but by the time a patient gets to our door, he or she should already be informed. So many patients don’t even know why they’re here. We need better education and some form of documentation establishing that the patient understands the procedure and its benefits and risks.”

Edwards says this patient education could take the form of a brochure and consent form, but it has to be communicated simply and directly. “There is a large population that doesn’t have strong reading skills,” she notes. Already concerned about their health, patients can be overwhelmed by the terminology of the radiologic world. Edwards thus underscores the need to open clear communication lines and give patients equal time to ask questions. “You really have to sense in each patient what they know about the procedure they’re having done,” she says. “Sometimes, the simple initiation of a phone call between a radiologist and the referring physician can change an order. Above all, we have to work as teams to make sure patients are informed. Working together is the key.”

Defensive Medicine

Education is critical, but any educational initiative runs headlong into the defensive medicine imperative driven by malpractice litigation. Citing the well-documented consequence of defensive medicine—excessive imaging—the American College of Radiology (ACR) outlined in a September 2003 American Journal of Roentgenology policy brief its support for tort reform.

“Defensive medicine,” the ACR wrote, “is estimated to account for 5% to 9% of the annual healthcare budget in the U.S., or $25 to $50 billion annually.” The ACR found that Medicare costs for patients with acute cardiac disease “were 5% to 9% lower in states with tort reform … with no appreciable change in patient outcome.” Nationwide, this translates into a predicted yearly savings of $50 billion in aggregate healthcare savings. The ACR also noted that patients residing in states with tort reform enjoy better access to subspecialty care.

Looking at this policy level, Forman says, “Industry needs to reduce radiation as much as possible on the current CT scanners and to work with clinicians to drive down their use of radiation.” In the final analysis, however, he also acknowledges the powerful driving force of malpractice fear.

“I think industry is very much afraid of communicating the radiation risk to patients,” he says. “I think they fear that doing so would potentially put themselves in the position of Big Tobacco and other industries that take on product liability risks.”

Forman envisions a day when a disgruntled patient will sue and attempt to link in court—albeit unsuccessfully, he opines—their lymphoma with “the 20 CT scans he had 20 years earlier in his life.”

Ultimately, the best defense is to learn, teach, and practice good medicine.

— Matthew Robb is a freelance writer based in the Washington, D.C., area and a frequent contributor to Radiology Today.

Radiation Dose Comparison

Estimates of the effective dose from a diagnostic CT procedure can vary by a factor of 10 or more depending on the type of CT procedure, patient size, and the CT system and its operating technique. A list of representative diagnostic procedures and associated doses are given in Table 1, which is adapted from a report by the European Commission.


Typical Effective
Dose (mSv) (1)

Number of Chest X-Rays (PA film)
for Equivalent Effective Dose (2)

Time Period for Equivalent Effective Dose
from Natural Background Radiation (3)

 Chest x-ray (PA Film)



 2.4 Days

 Skull x-ray



 8.5 Days

 Lumbar spine



 158 Days

 I.V. urogram



 304 Days

 Upper G.I. exam



 1 Year

 Barium Enema



 2.3 Years

 CT head



 243 Days

 CT Abdomen



 3.3 Years

1. Effective dose in millisieverts (mSv)
2. Based on the assumption of an average “effective dose” from chest x-ray (PA film) of 0.023 mSv
3. Based on the assumption of an average “effective dose” from natural background radiation of 3 mSv per year in the United States

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