News that the US is buying custom-made vans packed with something called backscatter X-ray capacity has riled privacy advocates and sparked internet worries about feds radiating Americans." American Science & Engineering, a Billerica, Mass.-company, tells Forbes it [has] sold more than 500 ZBVs, or Z Backscatter Vans, to US and foreign governments. The Department of Defense has bought the most for war zone use, but US law enforcement has also deployed the vans to [use] inside the US, according to Joe Reiss, a company spokesman. On [September 28], a counterterror operation snarled truck traffic on I-20 near Atlanta, where Department of Homeland Security teams used mobile X-ray technology to check the contents of truck trailers. Authorities said the inspections weren't prompted by any specific threat. Backscatter X-ray is already part of an ongoing national debate about its use in so-called full body scanners being deployed in many US airports. [Critics] worry that radiating Americans without their knowledge is evidence of gradually eroding constitutional protections in the post-9/11 age. "This is another way in which the government is capturing information they may lose control over. I just have some real problems with the idea of even beginning a campaign of rolling surveillance of American citizens, which is what this essentially is said [Vermont-based privacy expert Frederick Lane, author of American Privacy.]