A new study has debunked the widespread belief that radiations from X-rays and CT scans can cause cancer.

Scientists said that it is time to hurl away an unproven, decades-old theoretical model that has led many people, including doctors to believe otherwise.

Scientists used a model known as linear no-threshold (LNT) to estimate cancer risks from low-dose radiation such as medical imaging.

But, risk estimates based on this model are only theoretical and, as yet, have never been conclusively demonstrated by empirical evidence, they said.

The use of LNT model drives unfounded fears and excessive expenditures on putative but unneeded and wasteful safety measures, according to James Welsh, a professor at the Loyola University Chicago Stritch School of Medicine in US.

The LNT 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," Welsh and colleagues wrote in the study published in the American Journal of Clinical Oncology.

The said that the LNT 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.

They said that studies of atomic bomb survivors and other epidemiological studies of human populations have never conclusively demonstrated that low-dose radiation exposure can cause cancer.

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," they said.

The researchers suggested that the LNT model "should finally and decisively be abandoned."

The researchers reexamined the original studies, dating back more than 70 years, which led to adoption of the LNT model.