Most gases used in anesthesiology eventually end up in the atmosphere where they trap heat even more effectively than carbon dioxide. iStockphoto.com hide caption

itoggle caption iStockphoto.com

A CT scan of the brain shows the cerebellum, a small portion of each temporal lobe, and the sinuses. Andrew Ciscel via Wikimedia Commons hide caption

itoggle caption Andrew Ciscel via Wikimedia Commons

Army Captain William Krueger studies CT scans at the National Naval Medical Center in Bethesda, Md. CWO4 SETH ROSSMAN/NAVY VISUAL NEWS SERVICE hide caption

itoggle caption CWO4 SETH ROSSMAN/NAVY VISUAL NEWS SERVICE