For the first time a team of researchers have used the TSA style scanner on a fresco and discovered another hidden artwork underneath that went unnoticed by other techniques, according to Discovery News.
By using the terahertz spectroscopy, the technique used in airport body scanners, a postdoctoral researcher, J. Bianca Jackson of the University of Rochester, along with her colleagues studied the Italian Fresco at the Louvre Museum known as 'Trois Hommes Armes de Lances' (three men armed with lances). The team specializes in art conservation and restoration.
Source: Science World Report. Read full article. (link)