No evidence that CT scans, X rays cause cancer

But - say James Welsh, a radiation oncology professor in the Stritch School of Medicine at Loyola University, Chicago, IL, and colleagues - risk estimates based on the LNT model are only theoretical, and, as yet, "have never been conclusively demonstrated by empirical evidence."

They say persistent use of the LNT model by regulators and advisory bodies leads to unfounded fears and money being wasted on unnecessary safety measures.

As a result, many doctors are averse to recommending and using the most appropriate imaging procedures for their patients, and many patients are unnecessarily scared to undergo them.

Model ignores that human body repairs low-dose radiation damage

The LNT model maintains there is no safe dose of radiation - no matter how low the dose. It says you can work out the cancer risk of very low-dose radiation exposure by simply continuing in a straight line from the well-established, undisputed effects of high-dose radiation.

But such a model ignores the fact that the human body is able to repair damage caused by low-dose radiation - something that has evolved over millennia in humans and other organisms that are continually exposed to naturally occurring radiation in the environment. The authors note: