UCSF School of Medicine

Patient receiving a CT scan
Photo: Elisabeth Fall

By Susan Davis

You may have read the news accounts. Starting with a New York Times investigation of LA's Cedars-Sinai Medical Center in October, 2009 -- and then spreading across the country -- media reports have emerged that a number of patients, including babies, have been overdosed with radiation during CT scans. At the same time, studies by medical researchers are finding that the problem is not just anecdotal - that indeed, a lack of training, standards and regulations could be at the root of a widespread problem with over-radiation from CT scans. For patients, the news can be worrisome.

But UCSF professors have been on the leading edge not only of discovering the abuses, but developing systematic solutions to the problem. "We've got a lot of momentum going now," says Rebecca Smith-Bindman, MD, a professor in UCSF's departments of Radiology and Biomedical Imaging, Epidemiology and Biostatistics; and Obstetrics, Gynecology and Reproductive Sciences. "This hadn't been on people's radars. Now we know we have a problem. So we're fixing it."

In truth, researchers have known about the risk of radiation overdose during diagnostic imaging for a long time. When Dr. Fergus Coakley, who is vice-chair of clinical affairs at UCSF, as well as the chief of the Abdominal Imaging Section and professor of Radiology and Urology, arrived in the United States from his native Ireland in 1994, he was surprised at the lack of awareness here. "Radiologists in Europe and the UK had been concerned about this for years," he recalls.

But that all began to change in 2009. A report by the National Council on Radiation Protection in the spring of 2009 found that Americans were exposed to seven times as much radiation in 2006 as they were in the early 80s -- and that the increase was due to medical imaging. Then in the fall of that year, Smith-Bindman published a ground-breaking study in the Archives of Internal Medicine. That study found that even as the number of CT scans had "increased dramatically," the doses used for those CTs had also increased -- and that within and between hospitals, the amount of radiation used could vary considerably. A mean 13-fold variation existed between the highest and lowest dose of radiation from the same type of CT scans.

"75 million CTs are performed every year in this country," says Smith-Bindman, "the equivalent of one in four people getting one every year. That's three times higher than it was even a decade ago. Each CT scan is the equivalent of up to 30 to 400 chest x-rays."

"Given how frequently we are using CT," she continues, "it is incumbent on physicians to make these scans as safe as possible and only use them when medically necessary and when they are likely to improve patient health."

The fear is that radiation overdoses -- as happened in the cases that have been reported at a growing number of hospitals -- can result in immediate problems, such as hair loss, headaches, and confusion. But even when the correct amount of radiation is used, it can result in longer term problems, including cancer. "In the same issue of the Archives of Internal Medicine that ran my article," Smith-Bindman notes, "Amy Berrington de González published work showing that the current number of CT scans being performed in this country would result in 29,000 future cancers -- and she was using doses that were one half of what I was discovering can occur in actual practice."

No Certification, No Standards

A number of factors are driving the increase in both the number of and doses used in CT scans. First, the technology has improved, making them easier and faster to use and increasing the number of clinical situations in which CT scans are useful. "CT scans are now so fast we can get images of moving structures, like vessels, and arteries, allowing us to assess diseases like pulmonary embolism or coronary artery stenosis," Smith-Bindman says. "In the past, CT scans could not assess those problems. And because they're so much faster now, sometimes we'll scan the chest multiple times -- to assess the heart, lungs, and pulmonary vessels. That gives a complete picture of what's going on. But it also gives the patient four times the amount of radiation that they would have gotten with one single scan."

In addition, there are no national standards for becoming a CT technologist, Smith-Bindman says. "In many states (though not California), hair dressers must undergo more training and require greater certification than the technologists who are responsible for conducting CT exams," she notes. As a result, CT technologists may not know how to use the scanners properly or how to read the digital dose displays included on current models.

Equally important, while the FDA regulates the scanners themselves, there are no national, evidence-based guidelines on what dose of radiation should be used for which kind of CT scan, and this has resulted in what Smith-Bindman describes as "unacceptable variations" in the doses used in clinical practice. "Physicians may understand the cancer that they're trying to diagnose," Smith-Bindman says. "But they don't understand the risk of cancer associated with the CT scans they prescribe. We need to create and publish guidelines based on real data. And then we need to hold the facilities that conduct CT scans accountable for the radiation they deliver to their patients.

These guidelines can be based on standards adopted by professional organizations, or groups such as the National Quality Forum, or they can be established through legislative oversight, as has occurred for screening mammography." One legislative success she points to is the law passed in California in 2010, mandating that CT scan doses be entered into patients' medical records. "The frequency with which this imaging is used has reached such a high level that it is imperative that we begin to keep track of the doses that patients receive," she says. "Recording the dose in the patient's medical record will help physicians and patients alike keep track of how much radiation patients are receiving."

UCSF's Approach to Patient Safety

As health care experts across the country work to abate what some consider a national crisis, UCSF researchers have been working on solutions for their own patients. "UCSF is taking a proactive stance to the issue," says Coakley. "We've long had our house in order in regards to lower-dose protocols. Now we need to find better ways of using raw data to lower the doses of CT scans."

The Department of Radiology and Biomedical Imaging is already committed to the philosophy and practice of "ALARA" (As Low As Reasonably Achievable) in regards to the use of radiation for imaging -- and will often recommend that doctors order imaging methods that don't rely on radiation, including MRIs or ultrasound.

"We really don't know the long-term effects of low dose radiation, so we have taken the conservative approach that any unnecessary radiation should be avoided," says Ronald Arenson, MD, chairman of the Department of Radiation and Biomedical Imaging. "However, patients and their doctors should not shy away from getting CT procedures if they are needed."

While Smith-Bindman believes there is a role for quality guidelines, as well as legislative and regulatory oversight for CT, Coakley has his eye on technologist training, as well as better technology. One of the simplest ways to control radiation doses is to begin reporting those doses, he notes. "As the saying goes, 'if you can't measure it, you can't manage it,'" Coakley says. "What we're working towards is having techs check and record the dose both before they take the image -- when the machine displays what dose it thinks it will deliver -- and afterwards, when the machine displays the dose it really did deliver.”

Currently all the doses for all abdominal and pediatric CT scans are being recorded at UCSF. The California law passed last summer mandates that all CT scan doses start being reported in July, 2012. "I am very proud that our department has taken a leadership role in disclosing the excesses in radiation across the country that have been reported and substantially reducing the radiation from CT procedures at UCSF," says Dr. Arenson. "In fact," he notes, pointing to an article on such radiation strategies that appeared in a 2008 issue of the journal Radiology, "our department started doing so long before much attention was drawn to this issue."

Better, Safer Scanners

On the technology front, UCSF's current CT scanners, which use Adaptive Iterative Reconstruction technology, already emit 40% less radiation than standard CT scanners, Coakley says. "CT technology continues to improve, and soon we may be able to get equivalent CT images with 90% less radiation."

He's also hoping that future scanners will have built-in alarms or threshold alerts to warn technologists if a dose is too high, as well as a system that checks to see how many CT scans a patient has had in the past, so physicians can gauge the risk -- and utility -- of giving the patient another CT scan. "That way the doctor can see if the patient had a CT scan two weeks ago -- or the fact that the patient might have had four negative CTs in the last five years," Coakley says."And that makes it easier for a physician to ask, 'do we really need another one?'"

Coakley also notes that the trend of more and more CT scans being done is now slowing. "I don't know if it's because of the economy or a growing consciousness," he says. "And I do think that consciousness is good. But I also worry sometimes that we're losing track of the benefits as we focus on the risks. As CT scans have increased over the last 25 years, for instance, the number of exploratory laparotomies has decreased. I don't think that's a coincidence."

In the end, it will probably be a combination of a "top-down" legislative approach and "from the bottom-up" technologist training, both doctors say. "There are lots of ways to get to safer CT scanning," Smith-Bindman notes. "Going from the ground up is certainly important and I am currently participating in a clinical trial to educate technologists on methods to reduce doses, but we also need clear standards on how people should use the technology so that we can strike the right balance between its incredible potential for benefit, while minimizing any potential risks associated with its use."