Medical-imaging procedures always worth the risk?

This abdominal CT scan reveals extensive cyst formation over both kidneys and the liver of an adult.

(Credit: Steven Fruitsmaak)

Medical-imaging procedures such as computed-tomography (CT) and myocardial-perfusion scans are up drastically from just 15 years ago, according to a new study published in The New England Journal of Medicine.

CT scans alone are up four-fold, according to the study. These "worrisome" radiation doses--as many as 2 percent of cancers could be attributed to radiation during CT scans alone--justify more rigorous scientific scrutiny, according to lead investigator Dr. Reza Fazel at the Emory University School of Medicine in Atlanta:

Unlike the exposure of workers in health care and the nuclear industry, which can be regulated, the exposure of patients cannot be restricted, largely because of the inherent difficulty in balancing the immediate clinical need for these procedures, which is frequently substantial, against the stochastic risks of cancer that would not be evident for years, if at all.

Almost 1 million adults between the ages of 18 and 64 in five U.S. cities took part in the study between 2005 and 2007, with 655,613 of the adults undergoing one or more imaging procedures associated with radiation exposure. This puts the mean effective dose at 2.4 millisievert (mSv) per person per year, but that includes a wide range of differentiation, often along gender, age, and geographic lines.

Myocardial perfusion imaging alone accounts for 22 percent of the radiation dose from all study procedures, and CT scans of the abdomen, pelvis, and chest make up for about 38 percent, according to the study. Women and the elderly are exposed to the highest levels; for instance, while only 50 percent of adults ages 18 to 34 underwent a procedure, 86 percent of adults ages 60 to 64 did.

While most adults received less than 3 mSv annually, "effective doses of moderate, high, and very high density were observed in a sizable minority," according to the study. (Just more than 19 percent of those enrolled were defined as having "moderate" exposure, with just less than 2 percent having "high" exposure.)

With few exceptions, like mammography, most radiologic testing offers net negative results because there is little high-level evidence that cumulative exposure can produce real harm, such as cancer caused by testing, according to Dr. Michael Lauer of the National Heart, Lung, and Blood Institute in Bethesda, Md., in an accompanying article, "Elements of Danger--The Case of Medical Imaging."

Lauer adds that these tests should be subjected to rigorous clinical trials and that physicians should offer radiologic imaging with the same "humility" as when offering experimental treatments, taking a careful history of the patient to determine the cumulative dose of radiation already received: "If we began a national conversation about the dangers of ionizing radiation, it might cause enough discomfort to stimulate demand for high-quality evidence our patients deserve."

If as many as 2 percent of cancers could be attributed to radiation during CT scans alone, as recent estimates suggest, I'm surprised that not enough discomfort has been caused already.

[gwailo247]

Clinical need = need to pay for these machines = tremendous profits made from Medicare reimbursement from performing these tests.

When the HMO or PPO is going to eat the cost of it you have to threaten a lawsuit to get a CT scan, when they're going to bill the gov't, you have to practically stop them from performing several of them.

[TomMariner]

The most recent standards for assessing risk of producing a product include the proviso that the benefits of a risk be discussed as well as possible hazards. (Every medical device including Medical Imaging has to go through a strict development process overseen by the FDA.)

Granted, a medical imaging procedure can be misused as easily as drugs, surgery, or years of therapy, but in general there are two alternatives to seeing what is going on inside of you -- exploratory surgery or guessing. Both have a very very significant opportunity to do great harm.

In general "clinical trials" for individual products are used when a technology is not well understood. The science of ionizing radiation is always the same for a type of device and the effects well known. And very strict standards exist and are enforced.

[worried1]

Maybe I just have good insurance because they paid for 2 CAT scans and a chest X-ray. The second CAT scan with contrast was to recheck the results of the first. I do not have Medicare. I do not know the true dosage but believe the CAT scans are equal to a few years of normal background radiation. I would welcome an evaluation of the dosage and have expressed my concerns with my doctor but you do need to weigh the benefits and risks.

[globalist_agenda]

Defensive medicine. A lot of unnecessary tests are ordered by doctors to protect them from malpractice lawsuits. We don't need healthcare reform, we need tort reform. Also, why is the medical business the only business that doesn't publish prices? You expect to know how much a new car costs, how much the optional XM radio costs, but doctors, dentists, and hospitals pretend like medical care is free -- until the bill comes. What a crock.

[inanton]

Wow. How do doctors practice in the US? Complicated insurance considerations. Frequent malpractice suits. And then catch 22 situations like this... despite the reputation that the profession has, it seems like the society encourages the lawyers :)

[eCurmudgeon]

They also ought to do a study on how much radiation dental patients receive. It sometimes seems that dentists overdo the x-rays ... a patient can have as many as 14 x-rays in a single session.

[willdryden]

You have a bad dentist. You can do the whole mouth in 4 x-rays and the radiation is very localized to the cheek and jaw region.