The Hidden Cancer Costs of CT Scans

Are doctors overusing Computed Tomography Imaging? CT or “CAT” scans were performed over 90 million times in 2023. That’s according to a study just published in JAMA Internal Medicine, April 14, 2025. The name CAT scan sounds innocuous, but in fact it represents ionizing radiation, similar to X-rays. According to these researchers, those CT scans will likely lead to more than 100,000 future cancers. Don’t get me wrong, though. There are times when such imaging is absolutely essential. This research raises an important question, though: is a proposed CT scan absolutely necessary, or is it a “just in case” extra test? What questions should you ask before having a CT image?

How CT Images Have Grown in Popularity:

In 1980 there were just 3 million CT scans according to Harvard Health Publishing.

A research paper in the Archives of Internal Medicine published on December 14, 2009 reported:

“The use of computed tomographic (CT) scans in the United States (US) has increased more than 3-fold since 1993 to approximately 70 million scans annually.”

In the year 2023, 62 million Americans received 93 million scans. Clearly, CT examinations have become extremely popular in the 21^st century. Are they all necessary?

When CT Scans Are Essential:

There are many situations when a CT scan is critical. If an ER doctor suspects a  bleeding (hemorrhagic) stroke, computed tomography of the head is indispensable for a fast diagnosis. Such scans are also excellent at detecting appendicitis, bowel obstruction, pulmonary embolism (blood clots in the lungs), kidney stones and lung or colon cancer.

Have you ever had a CT scan? Was it essential or one of those “just in case” scans to rule out something serious? Such imaging can be very helpful but only if it is worth the risk.

My Personal Experience with a Critical CT Image:

I can speak from experience about the value of this diagnostic tool. Several years ago I developed incredible abdominal pain during an airplane flight from California to North Carolina. The pain was so bad during the flight that I considered asking the flight attendant to request an emergency landing.

I toughed it out, though, and when we arrived home a gastroenterologist friend advised heading straight to the emergency department of the nearest hospital. Within minutes I was getting a CT scan of my abdomen. The diagnosis was intussusception. My small intestine had slid into my large intestine and was causing bowel obstruction. Emergency abdominal surgery saved me.

CT Imaging Has Been Increasing!

On December 14, 2009 scientists published a landmark study in JAMA Internal Medicine.

Background on Computed Tomographic Scans:

“Despite the great medical benefits, there is concern about the potential radiation-related cancer risk.”

Here is what they concluded:

“The rapid increase in CT scan use in the US has raised concerns about potential cancer risks, because when a large number of people are exposed, even small risks could translate into a large number of future cancers in the population. Our estimates suggest that approximately 29,000 future cancers could be related to CT scan use in the US in 2007.”

Fast Forward to April 2025:

Research published in JAMA Internal Medicine (April 14, 2025) projected the number of future cancers due to radiation exposure from computed tomography (CT) examinations. The investigators used data from the University of California San Francisco International CT Dose Registry and modeled the effects of the radiation.

They estimated that approximately 103,000 cancers are likely to result from the 93 million scans conducted in 2023 on 60 million people. The risks are highest in children and adolescents, but many more adults undergo CT scans.

The scientists conclude that:

“CT is frequently lifesaving, yet its potential harms are often overlooked, and even very small cancer risks will lead to a significant number of future cancers given the tremendous volume of CT use in the United States.”

“In this study, approximately 5% of annual cancer diagnoses or 100 000 cancers were projected to result from CT utilization in 2023. Despite public attention to the potential adverse effects, CT use has grown significantly in the United States since 2009. In 2023, 93 million CT examinations were performed in the United States; in 2007, the number was 68.7 million—a 35% increase incompletely explained by population growth. Justification of use and optimization of dose, including consideration of the need for multiphase examinations, are the tenets of CT imaging and must be applied uncompromisingly to mitigate potential harm.”

The lead author of the research told the San Francisco Chronicle (April 14, 2025):

“The goal is not to scare patients, but to help them understand going forward they need to think about every time a CT is suggested. Do they need it? Do they understand why it’s done and work with their physician? Is this really a test I need now? Maybe it’s a test I can postpone.”

Dr. Rebecca Smith-Bindman is a radiologist and professor of epidemiology at the University of California, San Francisco.

As the first author on the study, she points out:

“CT can save lives, but its potential harms are often overlooked.

“Given the large volume of CT use in the United States, many cancers could occur in the future if current practices don’t change.

“Our estimates put CT on par with other significant risk factors, such as alcohol consumption and excess body weight,” she said. “Reducing the number of scans and reducing doses per scan would save lives.”

“There is currently unacceptable variation in the doses used for CT, with some patients receiving excessive doses.”

How Much Radiation Is Involved in a CT Scan?

When we first wrote about this issue roughly 16 years ago, we wrote:

“The radiation exposure from the computed tomography ranged from less than a year’s worth of background radiation to 13 times that. Some experts have compared the radiation in a single CT scan to that from 400 chest X-rays. Others say it is comparable to the radiation experienced by survivors of the Nagasaki atomic bomb blast. As a result, patients are now being urged to make sure that the scan is absolutely necessary before they agree to it.”

Today, it’s a lot more complicated. That is because there are a variety of computed tomography scanners on the market. There are cardiac scanners that are employed to look inside the heart. They can identify blockages and help interventional cardiologists prepare to open a blocked coronary artery or plan a valve replacement.

A head CT imaging machine would help diagnose a brain tumor or a stroke. A chest CT scanner can be helpful in identifying emphysema or lung cancer.

Different kinds of machines use different amounts of radiation. There are now low-dose scanners and even ultra-low-dose CT scanners. It is a bit challenging to try and put quantitative numbers behind each machine.

It has been estimated that a low-dose CT scanning machine:

“…emits only one-fifth of the radiation of a regular CT scan, making it safer for routine testing.”

Such low-dose equipment is especially helpful when screening for lung problems or checking for issues in a pediatric population.

The Radiological Society of North America suggests when ultra-low-dose CT might be appropriate:

“Denoised ultra-low dose CT (ULDCT) can effectively diagnose pneumonia in immunocompromised patients using only 2% of the radiation dose of standard CT, according to a study published in Radiology: Cardiothoracic Imaging (March 13, 2025).”

Questions to Ask Before Agreeing to a CT Scan:

Assuming you are NOT in an emergency situation, here are some questions you might want to ask regarding the benefits and risks of CT imaging:

• Why are you ordering a CT scan at this time?
• How important will these images be for analyzing or diagnosing my health problem?
• Would a low-dose CT scanning device or ultra-low-dose imaging equipment be appropriate for my situation? If so, can you request such a scan at a place that has this kind of equipment?
• Will my insurance pay for a low-dose scan?
• Will the results of a CT image alter my treatment plan?
• If I delay the scan, will it adversely affect my health?

Of course during an emergency, a CT scan can be crucial and all such questions should be ignored.

Final Words:

I greatly benefitted from a CT scan when I was suffering a bowel obstruction due to intussusception. It allowed the surgeon to make a fast diagnosis and start the surgical procedure in a timely fashion.

What about you? Have you ever had a CT scan? What was that procedure like? Did it reveal something important or was it a “just in case” initiative? Please share your experience in the comment section below. If you think this article has value, please share it with friends and family. You never know when someone might need to have the questions we posed above on hand to ask the physician who is recommending the scan. Thank you for supporting our work.