Staff Sgt. Kathleen Couillard, 28th Medical Operations Squadron bio-environmental engineering technician, determines specific testing locations during a radiation scatter survey at the dental clinic on Ellsworth Air Force Base, S.D., March 27, 2012. Data from these tests is recorded and processed by bio-environmental engineering technicians, who ensure facilities are free from harmful radiation. (U.S. Air Force photo by Airman 1st Class Kate Thornton/Released)