Growing evidence suggests that X-rays and CT scans do not cause cancer! 70 year old ideas led us down the garden path.
A review published in the American Journal of Clinical Oncology has nicely outlined that X-rays and CT scans probably don’t cause cancer (Siegel et al. 2016). The idea that these scans do cause cancer comes from 70 year old research which showed that mutation rates in flies followed a linear relationship with radiation dose. Meaning you can draw a nice line on a graph which plots the number of mutated flies on the y-axis and the dose of radiation of the x-axis. The relationship was then calibrated to humans following a number of radiation exposures including Hiroshima and Nagasaki. But there was a problem, the lowest dose given in these fly experiments were approximately 4000 times greater than what you would receive during an intensive CT scan. Recent, research has looked at lower doses of radiation and shown that the relationship between radiation and mutations is not linear and is probably a J shape. To draw an analogy the assumption the 70 year old linear relationship idea would be like giving 100 aspirin to 100 mice and noting they all died of overdose, then giving 50 aspirin to 100 mice and noting that half died, THEN assuming that if you gave 1 aspirin to 100 mice you would expect 1 to die. This is a bad assumption because as we know there are perfectly safe levels of aspirin. Similarly there ARE perfectly safe levels of radiation and it is likely that CT scan and X-rays are within this range.
Tristan Wadsworth