If you plan to travel by air for the holidays, or for any reason in the near future, really, it may require having a short yet intimate encounter with a TSA employee. The agency has been ramping up the use of so-called backscatter scanning machines in recent weeks, and the high-volume holiday travel season will be the first time many people will have to use them. The TSA’s procedures related to the scans and the aggressive pat-downs offered as an alternative have kicked up quite a bit of controversy.