Introduction
When a Journal of the American Medical Association (JAMA) paper in April 2025 claimed that CT scans could be responsible for 5% of all new cancer cases in the U.S., it set off waves of concern across the healthcare landscape. This brought a lot of attention to CT dose and conversation around whether patients are being put to a high risk of a future cancer from participating in imaging scans. The discussion expanded beyond medical professionals and made its way to the public sphere. Brad Lofton, CEO and a medical physicist of Colorado Associates in Medical Physics (CAMP), joins us to help shed some light on the initial paper and its response.
In this interview, Lofton breaks down what the study actually said, why its conclusions are misleading, and what patients and providers need to keep in mind about the true role of CT in modern medicine.
The Real Story Behind the CT Scan Cancer Study
Lofton began by addressing a recent article published in JAMA that suggested 5% of all new cancer diagnoses could be attributed to radiation from CT scans performed in 2023.
“The recent JAMA article indicates there will be 103,000 future, radiation-induced cancer incidents resulting from all CTs conducted in their analysis over the year 2023,” Lofton explained. “So that’s 5% of all new cancer diagnoses… due to having a CT scan done.”
At face value, that’s an alarming claim—but Lofton emphasized that the study lacks direct evidence and is instead based on outdated risk models.
“There are a few considerations here, and I would at the outset point readers to a recent rebuttal published by the AAPM [American Association of Physicists in Medicine] in April of this year [2025]. It is very concise and helpful, and I commend Cynthia McCollough, former AAPM president, for carefully articulating some of these considerations.”
“The first consideration for readers of the JAMA article is that this article really doesn’t present new data, and is similar to studies published as recently as 2009. The article does not provide direct evidence of new cancer cases resulting from CT scans, rather, it provides a statistical extrapolation from the number of CT scans performed in 2023 using carcinogenesis risk models that are over 20 years old. In other words, this study is based on many assumptions that are not directly observable in an epidemiological sense.”
The article’s conclusions relied heavily on the BEIR VII report—an aging risk model built on extrapolations from high-dose exposure scenarios, such as those experienced by atomic bomb survivors. These unproven assumptions lead to the conclusion that the more CT scans a person gets, the more likely they are to get cancer.
“The second consideration for readers is that dose rate matters. The risk models for radiation-induced carcinogenesis are based primarily on acute, high-dose exposures such as what atomic bomb survivors experienced, and this high-dose carcinogenesis relationship is well characterized. However, the amount of radiation used in diagnostic imaging exams such as CT is much less, by orders of magnitude, and the carcinogenic effect of low radiation levels is not well defined at all. In fact, there are several recent studies that have suggested a protective effect from low levels of radiation, although there is also a lack of direct evidence in that model as well. To discern observable epidemiological evidence for carcinogenesis at low radiation levels, you’d need a cohort of millions, and you’d need to be able to monitor them over a lifetime. Such a study is effectively impossible to conduct. Michael O’Connor is a physicist at the Mayo Clinic, and he’s given a lot of great lectures pointing some of these limitations out.”
“The fact is that as an American male, I have about a 40% chance of getting cancer in my lifetime by default, and there are many factors at play there, including diet, genetics, etc. To assume that we can accurately predict the additional cancer risk from a CT scan from within that natural background incidence is entirely presumptuous.”
“I would say the third consideration for those who read the article is that we now have over 40 years of data as CT has become more widely used in diagnostic imaging, and the reality is that we haven’t really seen the increase in cancers that would be predicted by the JAMA model. In fact, cancer incidence has been somewhat stable over recent decades even as CT and other imaging procedures have become more ubiquitous.”
“A fourth consideration for readers is that patient dose from CT exams has been dramatically reduced over recent decades, I would guess upwards of 20-40% depending on the study type.”
“The study was correct to point out that CT is becoming more heavily used, primarily because it’s an essential diagnostic tool, but concomitant to this increase in utilization has come a relative reduction in the dose per exam. New technology gives us better image quality at lower radiation dose.”
The result? Public confusion and hesitation around a technology that’s saving lives daily.
“CT scans prevent people from having unnecessary surgery. CT scans identify strokes. CT scans screen for heart disease and cancer… It is a very powerful diagnostic tool. In fact, since CT lung screening was more widely utilized, we’ve seen a decrease in lung cancer mortality, because it is being identified early using CT imaging.
What Patients and Providers Really Need to Know
For Lofton, one of the most irresponsible aspects of the JAMA study was its failure to frame CT risks in context.
“Any risk from a CT scan is far outweighed by the risk that you have as a sick person presenting certain symptoms,” he said. “The risk of the underlying disease is much greater than any risk imposed by the CT, which is negligible.”
Lofton is especially concerned about how sensational headlines impact both physician decision-making and patient behavior, ultimately putting lives at risk.
“Inevitably, physicians will stop ordering them as much and patients will decline them,” he warned. “And that’s going to have a much more serious impact on their health than if they had gotten a CT in the first place.”
Beyond fear, there’s a lack of awareness around how far CT imaging has come. Modern scanners deliver far less radiation than their predecessors, thanks to decades of technological progress.
“Our technology has gotten better. We’re getting better images with less radiation, which is… dismissed in this article,” he said.
When asked how he would respond to a patient worried by a headline, Lofton offered a grounding perspective: “The single takeaway I would give to a patient is, what is the risk of the underlying disease that you have that you need a CT for?”
Why the Radiation Risk Model Needs a Rethink
A large part of Lofton’s critique centers on the continued reliance on the BEIR VII report and its use of the linear no-threshold (LNT) model, which assumes that any amount of ionizing radiation exposure increases cancer risk in a straight-line fashion, regardless of dose.
“The creation of a mutation is not the same thing as a mutation that will cause cancer, which is carcinogenesis,” he explained. “Our DNA repairs itself all the time.”
The BEIR VII data, which stems primarily from high-dose exposures such as atomic bomb survivors, was never designed to model the low-dose levels seen in diagnostic imaging. Yet Lofton noted that researchers continue to stretch their assumptions far beyond the original context.
“They said… we have very little to no data on the low end of that… so we’re just going to draw a straight line… and assume there’s always a risk.”
This kind of extrapolation, he argued, is not only scientifically weak but dangerously misleading when applied to CT scans.
“There is no direct evidence of any person getting cancer from a CT scan in this analysis,” he added. “It’s all statistical extrapolation in nature.”
Lofton also discussed emerging interest in an alternative framework: radiation hormesis, the idea that low-dose exposure could actually have a beneficial, immune-stimulating effect.
“There seemed to be a protective effect,” he said, referring to research on people living in a region of China with naturally higher background radiation. “People were less susceptible to certain things.”
However, he cautioned against swinging too far in the opposite direction.
“Theoretically, it makes sense… But again, there’s just not a ton of data out there,” he said. “You don’t want to fall into the other ditch… There’s not a lot of evidence to support hormesis either. So we’ve got to avoid both ditches.”
Ultimately, Lofton called for a more evidence-based, nuanced understanding of radiation risk, one that neither exaggerates nor minimizes, and keeps patient outcomes at the center.
Conclusion
Brad Lofton’s message is clear: CT scans save lives. And while caution around radiation exposure is warranted, the way some scientific data is packaged for public consumption can cause more harm than good.
“These devices save lives,” Lofton emphasized. “They give physicians the information they need to make decisions about your care.”
For patients hesitant about a CT scan, he encourages asking the right question: “What is the risk of the underlying disease that you have that you need a CT for?” More often than not, the answer will point to the immense, life-saving value of the scan.
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This resource communicates information to the public in accordance with the AAPM Code of Ethics. The content presented is based on scientific studies, expert consensus, and professional experience in diagnostic and therapeutic medical physics.
Last updated: May 2025
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This resource is provided for general educational and informational purposes only and is not intended to constitute medical advice, diagnosis, or treatment, nor to replace the independent clinical judgment of a licensed physician or other qualified healthcare professional. Individual treatment plans, safety precautions, and clinical recommendations vary based on patient-specific factors and clinical context. Readers should consult their own licensed healthcare provider regarding any medical condition or treatment decisions.
