Some researchers claim that, despite wide belief, that exposure to Low-Dose Ionizing Radiation (LDIR) from computed tomography (CT) and X-ray medical imaging scans does **not** cause cancer.

Jeffrey Siegel and Charles Pennington wrote a [2015 article for Skeptic magazine](http://radiationeffects.org/wp-content/uploads/2015/12/Mismeasure-of-Radiation-Skeptic-Magazine-Vol-20-number-4-2015.pdf) arguing that the "Linear No Threshold" model for  was not supported by evidence, and that using this model to predict that LDIR was carcinogenic was incorrect.


[Eureka Alert](http://www.eurekalert.org/pub_releases/2016-02/luhs-npt020316.php) report that James Welsh, MD, made a similar claim in a paper published in the *American Journal of Clinical Oncology*.

Is there evidence to support or reject the idea that the radiation received from medical imaging equipment poses a cancer risk?