Can X-rays and CT scans cause cancer?

New York: The widespread belief that radiations from X-rays and CT scans can cause cancer has flaws and is based on an unproven theoretical model, suggests a study.

To estimate cancer risk from low-dose radiation, scientists used a model known as linear no-threshold (LNT) in the study published in American Journal of Clinical Oncology.

But risk estimates based on this model "are only theoretical and, as yet, have never been conclusively demonstrated by empirical evidence", wrote researcher James Welsh from the Loyola University in Chicago.

The use of LNT model drives unfounded fears and "excessive expenditures on putative but unneeded and wasteful safety measures", Welsh noted.

In the LNT model, the well-established cancer-causing effects of high doses of radiation are extended downward in a straight line to very low doses.

The model dissuades many physicians from using appropriate imaging techniques and "discourages many in the public from getting proper and needed imaging, all in the name of avoiding any radiation exposure", the researcher explained.

This model assumes there is no safe dose of radiation, no matter how small.

However, the human body has evolved the ability to repair damage from low-dose radiation that naturally occurs in the environment.

Studies of atomic bomb survivors and other epidemiological studies of human populations have never conclusively demonstrated that low-dose radiation exposure can cause cancer, according to the study.

Any claim that low-dose radiation from medical imaging procedures is known to cause cancer "should be vigorously challenged, because it serves to alarm and perhaps harm, rather than educate", the scientists suggested.

The LNT model "should finally and decisively be abandoned", the authors concluded.