NHS CT Scans Can Kill Cells And Damage Patient DNA, Study Finds

CT scans of the sort used throughout the NHS can damage DNA and kill cells, a study has found.

Whether the harmful effects increase the risk of cancer remains unclear, but scientists stress they are "not benign".

Experts who examined the blood of heart patients undergoing CT (computed tomography) scans found evidence of DNA damage and cell death.

The activity of cell repair genes was also boosted. Although most of the damaged cells managed to repair themselves, a small percentage died.

Dr Patricia Nguyen, from Stanford University in the US, said: "We now know that even exposure to small amounts of radiation from computed tomography scanning is associated with cellular damage.

"Whether or not this causes cancer or any negative effect to the patient is still not clear, but these results should encourage physicians toward adhering to dose reduction strategies."

CT scans produce 3D X-ray images showing structures such as organs, blood vessels, bones and tumours in great detail.

But the radiation doses are much higher than those of a standard X-ray, leading to concerns about the possible risk of cancer. A single CT scan exposes a patient to at least 150 times the amount of radiation from a single chest X-ray, according to the study authors.

The scientists, whose findings are reported in the Journal of the American College of Cardiology: Cardiovascular Imaging, point out that little is known about the long-term effects of low dose radiation.

Most knowledge of what radiation does to the human body is derived from the atomic bomb attacks on Japan at the end of the Second World War, when people were subjected to extremely high doses.

In 2007, the US National Cancer Institute estimated that 29,000 future cancer cases could be attributed to the 72 million CT scans performed in the country that year.

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Two years ago a patient record study of more than 10 million Australians, published in the British Medical Journal, found that having a CT scan increased overall cancer risk at least a year later by 24%.

A dose response was seen, with the risk increasing for each additional CT scan performed on a patient.

For the new study, tests were conducted on blood samples from 67 patients undergoing CT angiograms. The researchers used a variety of techniques to measure biomarkers of DNA damage and cell death before and after the procedure.

In their paper, the scientists said the findings raised the possibility that radiation exposure from CT heart scans "may cause DNA damage that can lead to mutations if damaged cells are not repaired or eliminated properly".

Harmful mutations in the DNA of cells that are not "culled" but allowed to proliferate are the root cause of cancer.

Dr Nguyen said: "We need to learn more because it's not a benign effect even at these low dosages. Our research supports the idea that maybe physicians shouldn't just use the best image quality in all cases.

"We shouldn't eliminate CT scans because they're obviously important, but you can make it safer by reducing the doses, by getting better machines and technology, and by giving patients something to protect them."

She added it was important to note that no DNA damage was detected in average weight patients receiving the lowest doses of radiation who had regular heart rates.

Professor Joseph Wu, director of the Stanford Cardiovascular Institute, said: "The use of medical imaging for heart disease has exploded in the past decade.

"These tests expose patients to a non-trivial amount of low-dose radiation. But nobody really knows exactly what this low-dose radiation does to the patient. We now have the technology that allows us to look at very subtle, cell-level changes."

7 Proven Ways To Prevent Heart Disease

2,000 extra daily steps = 10% lower risk(01 of07)

In this global study, adults over 50 who were at high risk of cardiovascular disease and diabetes who walked an additional 2,000 steps a day—about 20 minutes of brisk walking—reduced their risk of having a cardiovascular “event,” such as a heart attack or stroke, by 10 percent over the next six years. “Other than not smoking, nothing comes close to physical activity for prevention,” says Dr. Church. “Hundreds, if not thousands, of papers support it.” Achieving the goal of being physically active for 150 minutes a week, including strength training a couple of days a week, can reduce your cardiovascular risk by about 25 percent, he says. “There’s a dose response, which means the more you exercise, the more you benefit.” The biggest benefit, though, comes from going from sedentary to mildly active, such as walking 10 minutes a day. Says Dr. Church, “The biggest bang is just getting off the couch.” (credit:Shutterstock)

An 7 extra grams of fiber daily = 9% lower risk(02 of07)

In a meta-analysis of 22 studies, British researchers found that people who ate seven more grams of dietary fiber had a nine percent lower risk of heart disease. How much is that? A medium apple has 5 grams of dietary fiber, as does a half cup of cooked broccoli. A half cup of cooked lentils: 8 grams. Fruits, vegetables, beans, nuts, and whole grains are all good sources of fiber. “Fiber has beneficial effects on blood glucose and cholesterol, and it may keep your gastrointestinal tract healthier, reducing inflammation,” says Dr. Church. “Eating more fiber is also a marker of a healthier diet.” (credit:Shutterstock)

Daily glass of wine = 25% lower risk(03 of07)

“It’s pretty powerful,” says Dr. Church. “Drinking in moderation cuts your risk of heart disease by about 25 percent.” That’s defined as no more than one daily drink for a woman, two for a man. Not everyone can drink moderately, of course, but if you can, research shows it’s heart healthy.“It relaxes your blood vessels, so you can’t form a clot while alcohol’s on board,” says Dr. Church. “Any alcohol has benefits, but wine has a little more,” says Dr. Church. The healthiest pattern: “A drink or two every couple of days.” (credit:Shutterstock)

Multivitamins = zero heart benefit(04 of07)

The Agency for Healthcare Research Quality, a federal research agency, recently concluded that simply taking a multivitamin/multimineral pill won’t reduce your risk of heart disease. “It’s no surprise,” says Dr. Church. After all, preventing heart disease isn’t what multis are built to do—they’re to shore up nutrient deficiencies. “While the evidence for heart disease prevention isn’t there,” says Dr. Church, “taking multis won’t hurt you.” As for research that low vitamin D is associated with a 27 percent increased risk of developing heart disease, Dr. Church thinks it’s simply a marker for an inactive lifestyle, meaning since most people get their vitamin D from the sun, “people with high vitamin D levels are outside more—and probably more active,” he says. If you do have low D levels, Dr. Church supports taking supplements. But whether it will affect heart health isn’t fully clear. What he does think makes a difference: Omega 3 fatty acids, found primarily in fatty fish such as salmon. The American Heart Association recommends that healthy adults eat at least two fish meals a week. But if you don’t, won’t, or can’t, you may want to consider a 1-gram Omega supplement that includes both EPA and DHA, two forms of Omega 3s found in fish. While the heart disease preventive benefits of taking Omega 3 supplements hasn’t been established, says Dr. Church, “there is a lot of strong epidemiological evidence for Omega 3s. I’m a big proponent — I believe there’s value there.” (credit:Shutterstock)

Flu shot = 36% lower risk(05 of07)

This one has a catch—it’s about people who already have heart disease. A recent analysis found that in people with existing heart disease, getting the flu shot reduces the risk of cardiovascular events like a heart attack by 36 percent. “Getting the flu puts great stress on your body and increases the risk of having another heart attack,” says Dr. Church. A flu shot is a good idea for everyone—it’s not too late since flu peaks around the end of February, beginning of March!—and if you’re at high cardiovascular risk, or already have heart disease, that little jab could be a lifesaver. (credit:Shutterstock)

Mediterranean Diet = 30% lower risk(06 of07)

A major Spanish study found that men and women aged 55 to 80 who ate a Mediterranean diet were 30 percent less likely to have a heart attack or stroke, or die from heart disease, over the next five years. The most protective elements: olive oil as the primary fat, moderate alcohol (mostly from wine), lots of fruits, vegetables, nuts, legumes, and fish, and low consumption of meat. Just this week, a new American study of firefighters from the Midwest who followed a Mediterranean-style diet had lower cardiovascular risk factors: less belly fat, lower “bad” LDL cholesterol, and higher “good” HDL cholesterol. The great thing about Mediterranean studies is that they capture not just one healthy element but a pattern—a lifestyle. “We should look at risk factor clusters, and the Mediterranean lifestyle captures that,” says Dr. Church. Add the physical activity that’s part of a traditional Mediterranean lifestyle, and it’s really the big picture. (credit:Shutterstock)

A healthy lifestyle = 25% less chance of dying from heart disease(07 of07)

Talk about big picture. The Centers for Disease Control and Prevention recently estimated that if everyone didn’t smoke, ate a healthy diet, exercised regularly, achieved a healthy weight, and got regular checkups so they could control risk factors such as high blood pressure and elevated cholesterol levels, then death from heart disease would fall by 25 percent. That’s 200,000 lives saved – each year. (credit:Shutterstock)

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