Avoiding Diagnostic Imaging, Not Low-Dose Radiation, Is the Real Health Risk

Journal of American Physicians and Surgeons Volume 21 Number 3 Fall 2016 Diagnostic imaging with low-dose ionizing radiation helps physicians save lives and assist in prolonging good health. Numerous publications1-5 based on clinical, epidemiological, and ecological studies have claimed increased cancer risk associated with low radiation doses such as received from diagnostic imaging and other sources (e.g., nuclear worker exposures, some Chernobyl accident victims among the public). The increased risk is often evaluated based on the linearno-threshold (LNT) model, which assigns absolute or relative risk with any radiation exposure, including natural background radiation exposure. An important question addressed in this paper is how reliable are cancer risk estimates derived from such studies, especially when based on the LNT model. Results provided in Tables 1 and 2, as explained below, can be used to evaluate the plausibility of epidemiological study results claimed to indicate an increase in cancer or cancer mortality risk from exposure to low radiation doses, such as are received from an X-ray-computed tomography (CT) scan or chest X-ray. Such doses are very much less than 100 mGy (milligray). Thus, the absence of convincing evidence for harm (increased cancer risk) from 100 mGy would imply the lack of convincing evidence for harm from smaller doses associated with diagnostic imaging with single or multiple CT scans and chest X-rays. Some background information on different risk models and terminology used in epidemiological studies is provided in the following two sections.