WASHINGTON—Contrary to widespread belief, there is no proof that radiation form X rays and CT scans causes cancer, according to a study in the American Journal of Clinical Oncology. According to the study authors, the notion that X rays cause cancer is based on a linear no-threshold (LNT) model that is unproven and outdated.
The LNT model is used to estimate cancer risk from low-dose radiation, but according to corresponding author Dr. James Welsh, an oncologist at Loyola University Medical Center, the LNT estimates “are only theoretical and, as yet, have never been conclusively demonstrated by empirical evidence.”
For the study, authors examined original data dating back t the 1940s, which led to the adoption of the LNT model. However, a reexamination of the data used for the original studies does not support the LNT model.
While it is well established that high doses of radiation cause cancer, the LNT model extends these cancer-causing effects downward to very low doses in a straight line assuming no safe level of radiation, regardless of how small. However, the human body is indeed able to repair low-dose radiation damage present naturally in the environment.
The LNT model is based on studies that exposed fruit flies to different doses of radiation, concluding that there is no safe dose. Study authors argue that this conclusion is unwarranted because the experiments were not conducted with truly low doses of radiation. Moreover, a 2009 studythat exposed fruit flies to truly low levels of radiation did not support the LNT model.
Study authors also contend that epidemiological studies and studies of atomic bomb survivors do not demonstrate conclusively that low-dose radiation causes cancer.
In the study, Dr. Welsh and colleagues argue that using the LNT model creates unfounded fear and needless waste. They argue that the LNT model discourages doctors from using proper medical imaging tools and discourages patients from obtaining needed diagnostics. The study concludes stating that the LNT model “should finally and decisively be abandoned.”
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