How Safe Are Radiation Doses in Diagnostic Radiology? A Historical Perspective and Review of Current Evidence.

The "no dose is safe" linear no-threshold (LNT) model forms the basis for radiation safety in radiology practice. This model has its origins in observations of germline mutations in fruit flies exposed to X-rays. After World War II, quantitative risk estimates of radiation injury are primarily derived from the atomic bomb survivor Life Span Study. Current understanding of tissue response to radiation has raised doubts about the validity of LNT model at low doses encountered in the practice of diagnostic radiology. This article traces the evolution of basic radiation safety concepts and provides a bird's eye view of the Life Span Study and other studies which throw light on the matter. The arguments for an alternative, threshold, or even hermetic models of dose response are examined. The relevance of these developments to the nuclear power industry is also outlined.