X-rays and CT scans don't cause cancers: Study

New York: Man might have developed over the years the ability to repair damage from low-dose radiation from X-rays, CT scans and other medical imaging procedures, says new research.

In recent years, there has been widespread media coverage of studies purporting to show that radiation from X-rays, computed tomography (CT) scans and other medical imaging causes cancer.

"But such studies have serious flaws, including their reliance on an unproven statistical model," researchers said.

"Although radiation is known to cause cancer at high doses and high-dose rates, no data have ever unequivocally demonstrated the induction of cancer following exposure to low doses and dose rates," said corresponding author James Welsh from Loyola University Medical Centre in the US.

Studies that have found a cancer link to medical imaging typically employ a model called "linear no-threshold" (LNT). The LNT model assumes there is no safe dose of radiation, no matter how small.

"But although LNT is used by regulators around the world, the model 'is of questionable validity, utility and applicability for estimation of cancer risks'," the researchers said.

Contrary to the LNT model, there is compelling evidence that the human body has evolved the ability to repair damage from low-dose radiation, the study said.

For example, the mutation rate caused by low-dose background radiation in the environment is 2.5 million times lower than the rate of spontaneous mutations in the body.

So even if the LNT model were true, the small increase in mutations caused by low-dose radiation from medical imaging would be unlikely to overwhelm the body's defences.

"While many people focus on the purported risks of radiation in medical imaging, the more significant and actual risks associated with not undergoing an imaging procedure or undergoing a more invasive exploratory surgery are generally being ignored in both the scientific literature and the popular media," Welsh said.

The study appeared in the journal Technology in Cancer Research & Treatment.