Until The 1970s, X-Ray Machines Were Used For Which Of These Decidedly Non-Medical Uses?
Answer: Shoe Fittings
Today the very concept, let alone the practice, seems absolutely preposterous, but throughout most of the 20th century it was common to x-ray the feet of customers at shoe stores. From the early 1920s to the 1970s, “shoe-fitting fluoroscopes” were a regular fixture in large shoe stores in countries like the United States, Canada, the United Kingdom, Germany, and Switzerland.
The devices, metal constructs covered in finished wood and roughly the size of a file cabinet, allowed the user to place their feet inside the bottom of the device while looking down through a viewing porthole in order to see the x-ray image of their feet in the shoes. They typically included multiple viewing portholes so the shoe salesman, parents (or regular adult customers), and children could all see the x-ray output at once.
The devices were a costly gimmick that shoe stores employed to bring in customers under the premise that it allowed for a perfect shoe fitting–a dubious claim given that the x-ray merely showed the bones and not the flesh around them, which is also important for a good fit.
The devices were unregulated, used by non-medical personnel, and no records were kept of the exposure times or frequency for the various clients that visited the shoe stores. As such, it’s impossible to assess what long term effects there were in the general population from the machines except to infer that many individuals (especially sales staff) in countries where the practice was common received large doses of unnecessary X-ray radiation.