Every scientific theory can be debated, and indeed theories should be reassessed when new and compelling contradictory evidence arises. However, the linear no-threshold model remains the best, and certainly the most conservative, means of estimating the risk of exposing humans to varied levels of ionizing radiation. When considering the risks at low levels of exposure, the BEIR VII report rightfully shifted from an epidemiologic to a mechanistic approach. The BEIR VII report also appropriately considered and rejected the possibility of a threshold. With improved methods of DNA sequencing, additional insights into low-dose radiation effects could be pursued. The risk of cancer after most every medical imaging study is almost certainly extremely small and effectively dwarfed by the risks of a missed critical/actionable diagnosis. Thus, we concur that adequate radiation must be used to acquire diagnostic images. However, the available data indicate that a small risk of irreversible DNA damage does exist to exposure to relatively low-dose radiation and must be considered, especially in an era when patients undergo multiple low-, and cumulatively, high-dose imaging studies during their lives.