Amidst concerns over violations of privacy, Homeland Security aims to operate 450 new body scanners at over 29 airports across the country this year. "The federal government is starting to deploy full-body scanning machines to 11 airports across the United States, Homeland Security Secretary Janet Napolitano announced Friday. Forty body-imaging machines already have been put into use at 19 airports nationwide as part of a field test, according the Department of Homeland Security. The Transportation Security Administration expects to deploy 450 units by the end of this year. "By accelerating the deployment of this technology, we are enhancing our capability to detect and disrupt threats of terrorism across the nation," Napolitano said in a statement. The first of the new units are being installed Friday at Boston's Logan International Airport, according to a DHS statement. The imaging machines are being funded through the Obama administration's $862 billion economic stimulus plan. Under existing protocols, full-body scans are optional at airport checkpoints. Travelers who decline the scans are funneled to a location where they may be given a pat down and subjected to other tests such as swabs that can detect minute traces of explosives on hands or luggage."