In the world of modern medicine, computed tomography (CT) scans have become one of the most relied-upon diagnostic tools, capable of uncovering everything from internal bleeding and blood clots to tumors and fractures.
While their ability to provide detailed images of the body’s inner workings has been instrumental in saving countless lives, a growing body of research suggests that the benefits of these scans don’t always outweigh their risks — particularly when it comes to radiation exposure.
A new comprehensive analysis has raised fresh concerns about the widespread use of CT scans, estimating that a significant portion of future cancer cases in the United States could be traced back to radiation exposure from these diagnostic procedures. The findings point to an urgent need for both healthcare professionals and patients to reconsider when and how these scans are used.
A Medical Marvel With Unseen Consequences
CT scans work by using a series of X-ray images taken from various angles around the body, which are then processed to create cross-sectional images. These can be combined to form a three-dimensional picture of internal organs, bones, soft tissues, and blood vessels. This clarity makes CT scans especially valuable in detecting abnormalities that may be missed by traditional X-rays.
However, this level of detail comes at a cost. CT scans expose patients to significantly higher levels of radiation than standard X-rays. While alternatives such as ultrasounds and MRIs emit no radiation at all, CT scans are sometimes chosen for their speed and precision.
This trade-off has become increasingly scrutinized, as evidence mounts about the potential long-term health risks associated with repeated radiation exposure.
Escalating Use of CT Scans in the U.S.
According to the latest analysis, the number of CT scans performed annually in the United States has surged by approximately 30 percent since 2007. Today, an estimated 61.5 million Americans undergo a combined total of 93 million CT scans each year.
While many of these procedures are medically necessary, especially for patients with cancer or serious injuries, experts are now questioning whether some could be safely replaced with alternative imaging methods.
“While CT scans are very valuable, the potential harms of this type of medical scan are often overlooked,” says Rebecca Smith-Bindman, MD, an epidemiologist at the University of California in San Francisco School of Medicine, who led the recent study. “It’s seen as a ‘freebie’ — you get the information you need without any harm.”
Why CT Scans Are Frequently Ordered
CT scans are commonly ordered for a variety of reasons — from assessing trauma injuries and internal bleeding to detecting tumors, blood clots, and infections. In emergency situations, their ability to provide fast, comprehensive images is indispensable. But in non-emergency contexts, other imaging options might suffice.
“Those CT scans would be great to reduce, because it wouldn’t affect how someone is treated or our ability to get the information we need,” Smith-Bindman adds, pointing to the potential for overuse in everyday medical care.
Calculating the Cancer Risk: Lessons From History
To estimate the potential cancer risk posed by the high volume of CT scans being performed today, researchers relied on a model known as Beir VII. This model assesses a person’s increased cancer risk following radiation exposure and is largely based on data from the survivors of the atomic bombings of Hiroshima and Nagasaki in Japan during World War II. It also incorporates information from workers exposed to radiation in industrial settings and patients who received radiation therapy for cancer.
By applying this model to data from 2023 — including the number and types of CT scans performed, and the number of images taken per scan — the research team arrived at a sobering estimate. They projected that around 103,000 new cancer diagnoses in the United States each year could eventually be attributed to radiation exposure from CT scans.
Questions Patients Should Ask Before a CT Scan
Rather than discouraging patients from undergoing CT scans outright, Dr. Smith-Bindman emphasizes the importance of communication between patients and their healthcare providers. She encourages patients to actively participate in conversations about whether a CT scan is truly necessary.
“It’s not that patients should refuse CT scans. It’s that they should engage in conversations with their providers to see if there are instances where an MRI or ultrasound can be used instead, or if the scan can be delayed,” she explains.
In situations where a CT scan is unavoidable, Smith-Bindman recommends asking whether the amount of radiation emitted can be minimized. This is particularly relevant because previous studies, including one published in 2019 covering multiple countries, found significant variation in the radiation doses administered for CT scans — not only between nations but also among hospitals and imaging centers within the same country.
The Medical Standard: ALARA
Max Wintermark, MD, chair of the department of neuroradiology at the University of Texas MD Anderson Cancer Center in Houston, points out that radiologists are well aware of the risks associated with radiation and are trained to minimize it.
“Radiologists take radiation doses extremely seriously,” Dr. Wintermark notes. “We make every possible effort to lower the radiation dose to as little as possible, while still allowing us to gather the information we need to collect to help patients.”
This principle, known as ALARA — “as low as reasonably achievable” — guides radiologists in balancing the need for diagnostic clarity with patient safety.
However, Dr. Wintermark also highlights a practical limitation, explaining, “You still need to get the diagnosis at the end. If you lower the radiation too much, you still give them radiation exposure but then you don’t have the information you need.”
The Irreplaceable Role of CT Scans in Emergency Medicine
Despite the risks, there are situations where CT scans are irreplaceable. In emergency care settings, where time is of the essence, their speed and accuracy can mean the difference between life and death.
“When you have, for instance, a patient who has been involved in a very serious car accident, there are some injuries that can result in death quickly, so being able to get that scan quickly is important. Any delay in getting those images could result in losing the patient’s life,” Dr. Wintermark says.
The same applies to cases of suspected stroke, where immediate imaging is crucial for determining the appropriate treatment pathway. In such scenarios, alternatives like MRI — which can take around 40 minutes — may not be viable.
A Call for Greater Caution and Informed Choices
Ultimately, while CT scans will likely remain a staple of modern diagnostic medicine, both experts agree that more caution is warranted in their routine use. For non-emergency situations, it’s entirely appropriate for patients to ask their healthcare providers for a clear explanation of why a CT scan is being recommended and whether safer alternatives could be considered.
As Dr. Smith-Bindman stresses, the key is informed, shared decision-making. He said, “It’s not that patients should refuse CT scans. It’s that they should engage in conversations with their providers to see if there are instances where an MRI or ultrasound can be used instead, or if the scan can be delayed.”
With better awareness and dialogue between patients and physicians, unnecessary radiation exposure can be reduced — potentially lowering the future burden of cancer diagnoses linked to medical imaging.
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