Why This Study Made Headlines

CT scans are often called the “workhorses” of modern medicine. They’re fast, accurate, and can reveal life-saving details that a standard X-ray might miss. But a recent study made waves when it suggested that CT scans may eventually account for up to 5 percent of new cancer cases in the U.S. each year (Fernandez, 2025; Cassella, 2025).

That sounds worrying — so should we be concerned? Or is the risk being overstated? Let’s unpack what the science says, and what it really means for patients.

How CT Scans Work

A CT (computed tomography) scan uses X-rays, but instead of taking a single snapshot, the machine rotates around your body to create a detailed 3D image. This is why CT is so good at detecting problems like:

• Blood clots that can cause strokes.
• Hidden tumors or internal bleeding.
• Complex fractures and joint injuries.
• Organ damage after accidents.

In many cases, CT is the fastest, most reliable tool doctors have — which is why its use has skyrocketed in the last few decades.

The Cancer Risk Explained

Radiation is powerful energy. At high or repeated doses, it can damage DNA. If that damage isn’t repaired properly, it can lead to cells growing out of control — in other words, cancer.

The new UCSF study estimated that:

• 61.5 million Americans had a CT scan in 2023.
• This could result in about 103,000 future cancers each year.
• That’s roughly 5 percent of annual U.S. cancer cases.
• Children face greater risks because their cells are more sensitive, but CT is used more sparingly in kids.

The cancers most often linked to CT exposure include lung, colon, bladder, leukemia, and breast cancer. Scans of the abdomen and pelvis carry the highest projected risks.

Should You Be Worried?

Here’s where context matters. Experts emphasize that while the population-level numbers sound big, the individual risk is very small.

As radiology expert Cynthia McCollough explained:

“Any risk from a CT scan of a sick patient is likely much less than the risk of the underlying disease.”

In other words: skipping a CT that could diagnose a blood clot, stroke, or tumor early would almost always be far more dangerous than the scan itself.

The Debate Among Experts

Not all scientists agree on how much low-dose radiation increases cancer risk.

• Some groups, like the American Association of Physicists in Medicine (AAPM), say the risk is “too low to be detectable.”
• Others argue that data from radiation-exposed groups, like atomic bomb survivors, clearly shows that even low doses raise risk over time.

Despite the debate, one thing is clear: CT scans save lives, and doctors don’t order them unless they’re necessary.

Why Children Need Extra Care

Children are more sensitive to radiation, and their longer lifespans give more time for damage to show up later.

One study found that just 2–3 head CT scans in childhood could triple the risk of brain tumors, and 5–10 scans could triple leukemia risk (National Cancer Institute, n.d.).

That’s why pediatric CTs use special low-dose settings, and doctors are extra cautious about ordering them.

Safer Scanning: How Risks Are Being Reduced

The good news is that healthcare systems are already working to reduce unnecessary exposure:

• Justification: Doctors are urged to order CTs only when absolutely needed — not for routine headaches or mild sinus infections.
• Optimization: Following the ALARA principle (“as low as reasonably achievable”), CT machines are calibrated to use the lowest dose that still produces a clear image (CDC, 2024).
• Alternatives: When possible, doctors may choose ultrasound or MRI, which don’t use radiation.
• Monitoring: National registries and reporting requirements in places like California track CT doses to encourage best practices.
• Technology advances: Radiation doses in the U.S. dropped by up to 20 percent between 2006 and 2016, thanks to better equipment and protocols.

What This Means for You

If your doctor recommends a CT scan, here are some good questions to ask:

• Is this scan absolutely necessary?
• Are there safer alternatives like MRI or ultrasound?
• Will the scan use the lowest possible dose for my age and size?

For most people, the answer will be that the benefits outweigh the risks. But asking ensures you and your doctor are on the same page.

The Bottom Line

Yes, CT scans expose you to radiation, and over time that may slightly increase cancer risk. But the chance of that happening is very small compared to the risk of leaving a serious condition undiagnosed.

For patients: don’t be afraid of a medically recommended CT scan. For doctors and policymakers: the goal is clear — keep scans justified, doses as low as possible, and alternatives in mind when appropriate.

CT scans are not without risk, but they remain one of the most powerful tools modern medicine has to save lives.

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FAQs About CT Scans and Cancer

Q: How many CT scans cause cancer?
There’s no magic number. Risk depends on dose, age, and frequency. For most adults, an occasional scan is considered very low-risk.

Q: How dangerous is one CT scan?
Experts agree the risk from a single scan is extremely small — far outweighed by the potential benefit.

Q: Are CT scans safe for children?
Yes, when medically needed. But doctors are extra cautious, and pediatric scans use lower doses.

Q: Can I ask for MRI or ultrasound instead?
Sometimes. For brain, joints, or soft tissue, MRI or ultrasound may work. But for trauma or internal bleeding, CT is often the fastest, most accurate choice.

Q: Should I worry about multiple scans?
If you need repeated scans for a chronic condition, talk to your doctor about tracking exposure and minimizing unnecessary scans.

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References

Cassella, C. (2025, August 21). CT Scans Projected to Result in 100,000 New Cancers Across The US. Science Alert.
Centers for Disease Control and Prevention. (2024, February 26). Guidelines for ALARA – As Low As Reasonably Achievable. Radiation and Your Health.
Fernandez, E. (2025, April 14). Popular CT Scans Could Account for 5% of All Cancer Cases A Year. UC San Francisco.
Kritz, F. (2025, April 24). Study Says CT Scan Could Account for 5% of All Cancer Cases. What Do Radiologists Think? Verywell Health.
National Cancer Institute. (n.d.). Radiation Risks and Pediatric Computed Tomography (CT): A Guide for Health Care Providers. NIH.
Schmidt, C. W. (2012, March 1). CT Scans: Balancing Health Risks and Medical Benefits. Environmental Health Perspectives, 120(3), a118–a121. https://doi.org/10.1289/ehp.120-a118
WHO. (2022, April 12). Ethics and medical radiological imaging: A policy brief for health-care providers. World Health Organization.

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⚠️ Disclaimer: This article is for educational purposes only. It is not a substitute for medical advice, diagnosis, or treatment. Always talk with your healthcare provider about imaging tests recommended for you.