CT Scan Overuse Could Lead to Cancer Deaths

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It should be no surprise that overuse of CT scans and variations in radiation doses increase one’s chance of cancer. Recent studies have suggested the relationship before, but two new studies published in yesterday’s Archives of Internal Medicine are the first to correlate the amount of exposure and associated risks. The results are a wake-up call for the medical community and potential patients.

Researchers found that current scanners could attribute to 14,500 deaths every year they are used, the LA Times reported. New scanners are designed to use lower doses of radiation, but too many older machines pump out higher doses.

The glaring dilemma that radiation doses vary widely, even identical procedures within the same hospital, is alarming. Contributing factors are likely lack of standardized settings, and inconsistencies how technologists and radiologists use the imagining procedure in different patients, according to a study author, Rebecca Smith-Bindman. One investigation revealed that some patients obtained only one-tenth the radiation others received.

“These are doses we should be concerned about. They don’t have to be this high,” said Dr. Smith-Bindman. Consequently, a low radiation dose could hinder an adequate picture and not reveal abnormalities.

CT, or computerized tomography scans, provide excellent views of internal organs, detect tumors and injuries albeit increased exposure to potentially dangerous radiation. The CT process gathers data from multiple X-ray images but excessive X-ray exposure causes DNA mutations, which can lead to or exacerbate cancer.

The largest radiation doses are often used for coronary angiography, a procedure to ascertain blockages or abnormalities in the heart and major blood vessels. Under normal dosage, about 1 in 270 women and 1 in 600 men who get it at age 40 will develop cancer, said Dr. Smith-Bindman.

The results are more encouraging for a routine head scan. Only one in 8,100 women and one in 11,080 men will develop a tumor.

“For 20-year-old patients, the risks were approximately doubled, and for 60-year-old patients, they were approximately 50% lower,” wrote the researchers. Two-thirds of the cancers would be in women, who are more vulnerable to radiation.

“This study is being taken very seriously by radiologists,” said Dr. Alec Megibow, a professor of radiology at NYU Langone Medical Center. Although careless scanner use can lead to high radiation doses, he affirmed that with proper use, “the benefits of a CT scan far outweigh the risks.”

Overuse of radiation-based tests is a concern when they are performed to diagnose patients who have a known abnormality, but the concern is even greater when they’re used for screening purposes, said Amy Berrington, an investigator at the National Cancer Institute and an author for both papers. “You’re exposing a lot of healthy people to radiation,” she said.

What is a patient’s recourse? Dr. Rosaleen Parsons, diagnostic imaging department chair at Fox Chase Cancer Center in Philadelphia, suggests people keep records of the number of scans they receive, ask why repeat scans are needed, and inquire about alternate imaging, such as an MRI, to reduce radiation exposure.