How do you tell if a shoe is a good fit? Take a short walk? Squeeze the front-end with your fingers to make sure there is space for your toes? What about a dangerous, 20-second blast of unshielded x-rays? If you were buying shoes in the 1930s, 1940s and 1950s, it's likely that you regularly inserted a tootsie into one of these death-rays.

The wooden cabinets, possibly first built by a Clarence Karrer in Milwaukee in 1924, had the x-ray source in the base, and it would fire upwards through your foot and shoe. Due to a lack of any kind of shielding, it wouldn't stop there: the radiation would shoot right up into your baby-maker, clearly a perilous occurrence.

The machine, called a "Shoe-Fitting Fluoroscope" put out 50 kv from its x-ray tube, which - according to Wikipedia's figures for today's machines, isn't too bad:

In medical radiography voltage from 20 kV in mammography up to 150 kV for chest radiography are used for diagnostic. Energy can go up to 250 kV for radiotherapy applications.

The problem was repeat exposure. While it was recommended that children not be subjected to more than 12 doses a year, there was no such luck for shoe-store employees. According to the article Shoe-fitting with x-ray in National Safety News 62 by H. Bavley (1950), store clerks would put their hands into the beam to squeeze shoes during fitting. Worse still was the fate of a poor shoe model, "who received such a serious radiation burn that her leg had to be amputated."

Thank God there's nothing this dangerous around today. Like, you know, full-body backscatter x-ray machines in airports.

Shoe-Fitting Fluoroscope [ORAU.org via Kyle "Mr. Fixit" Wiens]