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Some CT Scans Deliver Too Much Radiation, Researchers Say

lankisterguy profile image
lankisterguyVolunteer
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Some CT Scans Deliver Too Much Radiation, Researchers Say

March 14, 2025 by Joanne Kenan medscape.com/s/viewarticle/...

Rebecca Smith-Bindman, a professor at the University of California-San Francisco medical school, has spent well over a decade researching the disquieting risk that one of modern medicine’s most valuable tools, computerized tomography scans, can sometimes cause cancer.

Smith-Bindman and like-minded colleagues have long pushed for federal policies aimed at improving safety for patients undergoing CT scans. Under new Medicare regulations effective this year, hospitals and imaging centers must start collecting and sharing more information about the radiation their scanners emit.

About 93 million CT scans are performed every year in the United States, according to IMV, a medical market research company that tracks imaging. More than half of those scans are for people 60 and older. Yet there is scant regulation of radiation levels as the machines scan organs and structures inside bodies. Dosages are erratic, varying widely from one clinic to another, and are too often unnecessarily high, Smith-Bindman and other critics say.

“It’s unfathomable,” Smith-Bindman said. “We keep doing more and more CTs, and the doses keep going up.”

One CT scan can expose a patient to 10 or 15 times as much radiation as another, Smith-Bindman said. “There is very large variation,” she said, “and the doses vary by an order of magnitude — tenfold, not 10% different — for patients seen for the same clinical problem.” In outlier institutions, the variation is even higher, according to research she and a team of international collaborators have published.

She and other researchers estimated in 2009 that high doses could be responsible for 2% of cancers. Ongoing research shows it’s probably higher, since far more scans are performed today.

The cancer risk from CT scans for any individual patient is very low, although it rises for patients who have numerous scans throughout their lives. Radiologists don’t want to scare off patients who can benefit from imaging, which plays a crucial role in identifying life-threatening conditions like cancers and aneurysms and guides doctors through complicated procedures.

But the new data collection rules from the Centers for Medicare & Medicaid Services issued in the closing months of the Biden administration are aimed at making imaging safer. They also require a more careful assessment of the dosing, quality, and necessity of CT scans.

The requirements, rolled out in January, are being phased in over about three years for hospitals, outpatient settings, and physicians. Under the complicated reporting system, not every radiologist or health care setting is required to comply immediately. Providers could face financial penalties under Medicare if they don’t comply, though those will be phased in, too, starting in 2027.

When the Biden administration issued the new guidelines, a CMS spokesperson said in an email that excessive and unnecessary radiation exposure was a health risk that could be addressed through measurement and feedback to hospitals and physicians. The agency at the time declined to make an official available for an interview. The Trump administration did not respond to a request for comment for this article.

The Leapfrog Group, an organization that tracks hospital safety, welcomed the new rules. “Radiation exposure is a very serious patient safety issue, so we commend CMS for focusing on CT scans,” said Leah Binder, the group’s president and CEO. Leapfrog has set standards for pediatric exposure to imaging radiation, “and we find significant variation among hospitals,” Binder added.

CMS contracted with UCSF in 2019 to research solutions aimed at encouraging better measurement and assessment of CTs, leading to the development of the agency’s new approach.

The American College of Radiology and three other associations involved in medical imaging, however, objected to the draft CMS rules when they were under review, arguing in written comments in 2023 that they were excessively cumbersome, would burden providers, and could add to the cost of scans. The group was also concerned, at that time, that health providers would have to use a single, proprietary tech tool for gathering the dosing and any related scan data.

The single company in question, Alara Imaging, supplies free software that radiologists and radiology programs need to comply with the new regulations. The promise to keep it free is included in the company’s copyright. Smith-Bindman is a co-founder of Alara Imaging, and UCSF also has a stake in the company, which is developing other health tech products unrelated to the CMS imaging rule that it does plan to commercialize.

But the landscape has recently changed. ACR said in a statement from Judy Burleson, ACR vice president for quality management programs, that CMS is allowing in other vendors — and that ACR itself is “in discussion with Alara” on the data collection and submission. In addition, a company called Medisolv, which works on health care quality, said at least one client is working with another vendor, Imalogix, on the CT dose data.

Several dozen health quality and safety organizations — including some national leaders in patient safety, like the Institute of Healthcare Improvement — have supported CMS’ efforts.

Concerns about CT dosing are long-standing. A landmark study published in JAMA Internal Medicine in 2009 by a research team that included experts from the National Cancer Institute, the Department of Veterans Affairs, and universities estimated that CT scans were responsible for 29,000 excess cancer cases a year in the United States, about 2% of all cases diagnosed annually.

But the number of CT scans kept climbing. By 2016, it was estimated at 74 million, up 20% in a decade, though radiologists say dosages of radiation per scan have declined. Some researchers have noted that U.S. doctors order far more imaging than physicians in other developed countries, arguing some of it is wasteful and dangerous.

More recent studies, some looking at pediatric patients and some drawing on radiation exposure data from survivors of the atomic bomb attacks on Hiroshima and Nagasaki in Japan, have also identified CT scan risk.

Older people may face greater cancer risks because of imaging they had earlier in life. And scientists have emphasized the need to be particularly careful with children, who may be more vulnerable to radiation exposure while young and face the consequences of cumulative exposure as they age.

Max Wintermark, a neuroradiologist at the MD Anderson Cancer Center in Houston, who has been involved in the field’s work on appropriate utilization of imaging, said doctors generally follow dosing protocols for CT scans. In addition, the technology is improving; he expects artificial intelligence to soon help doctors determine optimal imaging use and dosing, delivering “the minimum amount of radiation dose to get us to the diagnosis that we’re trying to reach.”

But he said he welcomes the new CMS regulations.

“I think the measures will help accelerate the transition towards always lower and lower doses,” he said. “They are helpful.”

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Vlaminck profile image
Vlaminck

thanks for that discussion

AussieNeil profile image
AussieNeilPartnerAdministrator

Thanks Len,

I would say that with respect to CLL, general oncologist "U.S. doctors order far more imaging than physicians in other developed countries" or US CLL specialists. Seeing a CLL specialist is highly likely to significantly reduce the number of scans ordered for CLL management, because they have the patient experience to be able to mostly fairly accurately determine CLL progression without needing scans.

With CLL, we have the added risk of less effective surveillance and elimination of incipient cancers by our cytotoxic and NK lymphocytes. :(

Wayne Wells ThreeWs published a series of posts on his investigations into CT scanners, which interested members can find by selecting the ThreeWs link and looking by through his posts.

Neil

SeymourB profile image
SeymourB in reply toAussieNeil

AussieNeil -

There's a lingering problem of standard of care in clinical trials. I tried to negotiate MRI's instead of CT for lymph node and spleen tracking, but M.D. Anderson refused. We need more CLL experts to push for us. An MRI can do the job lymph node and spleen job. An MRI might not be the best modality for some other tumors - I'm really not sure. But that's not the point in a trial, is it?

Lymph node and spleen sizes are quite arbitrary in any case, spleen especially so. Different radiologists might read spleen size differently or use different terminology in the report to describe size. The iwCLL only says "Massive (ie, >=6 cm below the left costal margin" or progressice or symptomatic splenomegaly" for treatment criteria. They say "Spleen size <13cm" for complete remission without specifying the axis or orientation. The iwCLL only says "Massive nodes (ie, >=10cm in the longest diameter) or progressive or symptomatic lymphadenopathy" for starting treatment, and "none >= 1.5cm" for complete remission - which I assume is in any axis. I sometimes wonder if this wording is intended to allow arbitrary treatment or denial of treatment.

A big issue in the U.S. is the insane price of MRI's. It's probably 10 times that of other countries, and can be double the cost of a CT. I'm not sure how much of it is due to how they're financed and how long they're used. I've noticed that there are secondary radiology imaging services whose equipment is not brand new, but charging just below a nearby hospital. It may be in good operating condition or not.

=seymour=

AussieNeil profile image
AussieNeilPartnerAdministrator in reply toSeymourB

There's also the problem that the iwCLL recommends CT scans over other scan types, so all the historical clinical trial data records for comparison purposes are from CT scans. :(

LeoPa profile image
LeoPa in reply toSeymourB

An MRI cost about 260 EUR in Slovakia last time I checked. I hear these go into the thousands in the US. What a ripoff.

SofiaDeo profile image
SofiaDeo in reply toSeymourB

I would think the wording "progressive or symptomatic" points more towards "inclusion to treat". If any number of small nodes are growing, or if a patient is having any symptoms and there is a nearby enlarged node affecting blood flow, a nerve, etc., one can treat regardless of other criteria.

It's kind of how I started on my treatment path at initial diagnosis. I wasn't yet anemic, neutropenic, thrombocytopenic, nor did I have enlarged nodes. I had a full body PET since my initial workup was for an acute process; my nodes weren't enlarged, but I lit up like a Christmas tree, there was activity everywhere.

But boy did I have symptoms. Drenching night sweats, unable to finish a workday from exhaustion, making mistakes at work. I paid out of pocket for FISH because at that time, the hem-onc said serial bloodwork 3 months apart was part of the diagnostic criteria for CLL before insurance would pay. The flow cytometry had come back "CLL" so IDK why the insurance was being huffy about it. Anyway, I wanted to know FISH sooner, and was glad I did. With the TP53/del 17p results, I then knew "the usual" was a waste.

Some years ago, I knew a technician that worked in Guy's hospital (London, England). He told me the CT scanner (and other equipment equipment) wasn't maintained as regularly as it should be, because of budget constraints and the incompetence of management.

Flute117 profile image
Flute117

I’m surprised I don’t glow in the dark given how many scans I’ve had. With the SLL presentation of this disease, it’s difficult to follow without scans. I wish MRIs were more affordable in the US.

Smakwater profile image
Smakwater in reply toFlute117

Took the words out of my mouth!

Bobby9toes profile image
Bobby9toes in reply toFlute117

Same with me. I’ve had 2 PET and 3 CT scans of just my head in the past year, one with contrast ordered by my ophthalmologist because I was having double vision and he thought I may have had a mild stroke. Turns out it was from allopurinol. I asked my oncologist if I would be getting another PET and she said no more scans because of the radiation exposure.

Reetywell71 profile image
Reetywell71

Hi all. Since my CLL has only had lymph presentation. Normal labs so far. I have had 2rounds of CT scans with contrast since 6/24. I am very aware of the radiation exposure. Last ct in 11/24 revealed resolution of all nodes with severe reduction in my largest node 1.9 which is what got me started on brukinsa last July. I’m on 160mg/day reduced dose. Node was then 6cm. My question is this. Is there any other testing to monitor nodes? US MRI blood markers? Does having contrast give more radiation? I go to MD Anderson in Jacksonville Fla thank you!

lankisterguy profile image
lankisterguyVolunteer in reply toReetywell71

MRI & Ultrasound don't add ionizing radiation - but they have more labor & cost involved, so they may require some push back / negotiations with the physician to use them instead of CT scans.

Oral contrast in regular CTs usually does not add radiation.

PET CT scans (radio active tracer injection) add more radiation so should be limited to the highest level of need only

Reetywell71 profile image
Reetywell71 in reply tolankisterguy

What about injected contrast for a ct not PET

lankisterguy profile image
lankisterguyVolunteer in reply toReetywell71

I have not had an injected contrast looking for lymph nodes & spleen, but perhaps for contrasting arteries & veins for heart exams.

One of our more experienced medical professionals would need to opine whether that would involve a radioactive tracer or an inert xray visisble agent like Barium.

jerryjerry profile image
jerryjerry

I have had an interesting "side effect" of ct scans. Having been in a clinical trial for CLL, I have had many scans during and following up treatment. One scan showed a tumor in my lung that was melanoma. A very big surprise. Early treatment for that may have saved my life. Also, as an older man, I have a number of medical issues ranging from lung problems to vertebrate deterioration. When I see a specialist for these issues, they can look at my collection of scans. Very helpful, because they might not be concerning enough to require my medical provider (Medicare) to order a new scan.

InFlorida profile image
InFlorida in reply tojerryjerry

You sound like me….. I always take my IPAD to various doctor’s appointments so they can review my last “whatever”. As you mentioned, it’s been helpful for a specialist review the CT, MRI, etc during my appointment. That has ruled out tests or specified procedures they wanted to do.

Good luck, Randy

SeymourB profile image
SeymourB

This web page has phenomenal info on lymph node imaging by various imaging methods:

Radiology Key - Lymph Node Imaging Techniques and Clinical Role radiologykey.com/lymph-node...

It has great diagrams for where lymph nodes are.

However, it doesn't address the specific needs of clinical trials, as far as I can tell.

Perhaps Brian Koffman can weigh in with his experience.

=seymour=

BigDee profile image
BigDee

Hello lankisterguy

Great timing, I get another CT scan at end of this month, 5th one. 😒

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