Back in the 1940s, when plain old X rays were considered high tech, shoe salesclerks would often determine children's shoe size by X-raying their feet. Never mind that the same thing could have been done with a wooden ruler. Fluoroscopes, as the X-ray devices were called, were promoted as the scientific way to guarantee a proper fit. By the mid-1950s, however, it was clear that many fluoroscopes were badly maintained and ended up subjecting customers--not to mention salesclerks--to potentially dangerous amounts of radiation. Soon the machines were banned.
I was reminded of this bit of medical lore when I heard about...